Spodumene theoretically contains 8.03% Li2O and therefore the production of this mineral is greatly increasing because of the expanded use of lithium in the manufacture of high temperature insoluble lubricants, ceramics, pyrotechnics, non-ferrous welding fluxes, air purifying agents, and hydrogen isotopes.
The problems of spodumene mineral dressing depend on the amount of ore deposit, weathering and presence of associated gangue minerals. Weathered mineral surfaces must be thoroughly cleaned for selective flotation. Slimes interfere with selective flotation and also consume expensive reagents. Therefore, the slimes must be eliminated prior to conditioning and flotation. Concentrates should be about 6.00% Li2O.
Fatty acid or soap flotation of spodumene is one well established recovery method, but pulverized or ground particle surface conditions generally necessitate pre-flotation treatment. This involves high density agitation with cleaning agents such as sodium silicofluoride, trisodium phosphate, or sodium sulphide with sodium hydroxide. The pulp is then deslimed.
Agitation with anionic collectors, followed by flotation, will often result in satisfactory spodumene concentration when the spodumene is to be floated. Oleic acids and soaps work well in neutral and slightly alkaline pulps, while naphthenic acids, sulphonated castor oil, etc., work best in an acid pulp.
The flowsheet shown is based on recommendations which involve the froth removal of gangue minerals in an alkaline circuit with an amine collector. The spodumene is depressed with dextrine and removed as a high grade concentrate. Since this method is selective for the separation of mica, feldspar, and quartz, it solves the problem of marketing all possible products. A Mineral Jig is included to recover a heavy mineral concentrate.
Mine run ore is usually bulky to avoid fines and definitely requires a rail grizzly to limit the size of coarse ore fed to the jaw crusher. Two stage, open circuit crushing is satisfactory in the 200 ton per 8 hour production range. The resulting fine ore is smaller than or .
A stationary grizzly, set at approximately 1 opening, removes undersize from the primary jaw crusher feed. A Vibrating Screen removes the undersize from the secondary crusher feed. Removal of undersize reduces the amount of resulting fines and increases the capacity of the equipment.
The Steel Head Rod Mill has proven extremely satisfactory for grinding such pegmatitic mineral as feldspar and spodumene. The grinding circuit should have a controlled feed rate which is accomplished with a Adjustable Stroke or variable-speed Belt Feeder. Sufficient fine ore-bin storage should be available for at least one day capacity, and preferably more storage should be available.
The pre-flotation treatment generally begins at the rod-mill. A cleaning agent such as sodium silicofluoride, trisodium phosphate, or sodium sulphide with sodium hydroxide is added with the fine crushed ore to the rod mill and grinding is accomplished with a dilute pulp (25-35% solids). A Spiral Screen on the rod mill discharge eliminates tramp oversize from the grinding circuit, which is closed with a Vertical Centrifugal Sand Pump and Vibrating Screen. The vibrating screen is equipped with stainless steel screen cloth for 20 to 30 mesh separation.
The vibrating screen undersize ( 20 mesh range) is then deslimed in a Hydroclassifier and dewatered in a Rake Classifier after the pulp has been processed in a Mineral Jig. The jig removes a heavy mineral concentrate such as tin and columbium.
High density conditioning in the 70-75% solids range is very important to prepare mineral surfaces and assure proper reagent coating. Therefore, heavy duty Agitators are used. The duplex Agitator gives high concentration of horsepower and eliminates short circuiting.
The deslimed and washed pulp at (70-75% solids) is conditioned for about 5 minutes with a .5 lb./ton to approximately 1 lb./ton amounts each of the reagents as follows: a pH regulator such as lime; dextrine; amine acetate such as Armac T; and an alcohol frother. The pH is kept in the 10-11.5 range due to the unstable tendency of the amine collector above pH 11.5.
Reagent preparation involves little difficulty, as the liquid and dry reagents can be easily fed to conditioner with Reagent Feeders. However, the viscous amine reagents in bulk form generally require heat and agitation to provide a satisfactory liquid feed.
The conditioned pulp is diluted to approximately 20% solids for flotation in Sub-A Flotation Machines of standard steel construction. The cell to cell type machine with spitzkasten and froth paddles is used as well as the open-flow type. The open-flow machine has some advantage in coarse sand handling characteristics, and sand gates are placed very near to the bottom of the machine to improve passage of the 20 mesh sand fraction. Conical impellers and hood wearing plates of molded rubber construction give satisfactory service for this coarse, abrasive job. However, molded rubber receded disc impellers and diffuser type wearing plates also give satisfactory results when operated at speed higher than the conical disc impellers.
The froth product from initial rougher flotation represents gangue contaminants and is cleaned in additional flotation cells with more reagents to increase recovery of spodumene. No attempt is made in the rougher circuit to remove iron minerals.
The combined rougher and cleaner tailing, which is the spodumene product with iron mineral contaminants, is then washed in a rake classifier and thickened for conditioning at 70-75% solids. Reagents forthe removal of iron minerals include a combination such as hydrofluoric acid for a pH of 5, sodium resinate and a frother.
The conditioned pulp is then diluted to a 20-25% solids for flotation. Complete removal of iron minerals along with some remaining feldspar is accomplished in a froth product which is small and is discarded.
Although not indicated on the flowsheet, the final cleaner gangue froth, which contains feldspar and mica, can be processed in an acid circuit for the recovery of mica first. Then hydrofluoric acid amine flotation is used to separate feldspar from quartz.
The spodumene concentrate is discharged at the tailing discharge of the flotation machine and is ready for final processing. The spodumene pulp contains approximately 20% solids and must be dewatered before filtration to reduce the volume of filtrate. Dewatering to 20% moisture is accomplished in a Rake Type Classifier with little or no loss of solids in the water overflow.
The classifier sands are filtered best on a top feed or horizontal filter. Due to the fast settling, granular nature of the spodumene, conventional drum and disc filters are unsuitable. Filtration reduces the moisture content to less than 10% and the filter discharge is ready for drying.
Direct fired Standard Rotary Dryers satisfactorily remove the balance of the moisture. A Vibrating Screen removes any tramp material that finds its way into the flotation circuit, and the spodumene is then ready for shipment to market or chemical processing for recovery of lithium salts.
The report includes a very detailed demand analysis (i.e. Li-ion batteries with a look at cathode chemistry for lithium carbonate vs. lithium hydroxide, and the relative lithium content for various types of oxide cathodes, plus lithium-ion battery usage by different market segments including Passenger Electric Vehicles (EV), E-Buses, personal electric mobility (E-Bikes), grid storage, and consumer electronic products, as well as more traditional Industrial applications including ceramics and glass ceramics, greases & lubricants, metallurgical powders, air and purification). They forecast the lithium demand to grow by 81% from the current 192kt lithium carbonate equivalent (LCE) to 347kt LCE by 2020, and by 259% to 687kt LCE by 2025 (Figure 88), representing a CAGR of 14% across all demand sectors, driven by demand for Li-ion battery-based electric vehicles accounting for 38% of all lithium demand by 2025 (from ~6% in 2015), as well as significant demand from the grid storage sector, which they forecast will account for 13.6% of all demand by 2025 (Figure 89 & 90).
On the supply side, they estimate global supply at 176kt LCE in 2015, with production dominated by six operations owned by four major companies (representing 91% of total market share, including Albemarle (ALB-US, not covered), SQM (SQM-US, not covered), FMC Corp (FMC-US, not covered), and Sichuan Tianqi Lithium Industries (002466-CH, not covered) see Figures 15 and 16 below. The report includes a summary of the two primary mineral sources for Lithium production, their associated metallurgical recovery processes, and capex & operating cost profiles:
a) lithium brine deposits are formed through the leaching of volcanic rocks in basin depositional environments. Li is extracted from brines via a process involving the pumping of brine from the sediment basin, concentration via evaporation, and purification through solvent extraction, absorption, and ionic exchange, with the end product mainly in the form of refined Li2CO3
b) Hard rock spodumene deposits are comprised of lithium-bearing, aluminium silicate mineral which mostly occurs in lithium-rich pegmatites (granite-like igneous rock composed of quartz, feldspar and mica). Spodumene is usually recovered through conventional open pit mining methods and beneficiated via gravity techniques where the ore is concentrated from 1-2% Li2O to a grade of ~6% Li2O.
In determining an expected supply side response, they have analysed over 60 lithium projects around the globe, with 19 advanced stage projects offering potential for a total of ~400kt LCE in new supply within the next 5-6 years (see Figure 26 below), with two to commence production before the end of 2016 (Galaxy/General Minings Mt Cattlin spodumene operation currently being commissioned and the Mt Marrion spodumene project owned by a consortium consisting of Jiangxi Ganfeng Lithium, Mineral Resources, and Neometals). They have categorised the modelled new supply sources into various categories (Figure 27):
Market Surplus/Deficit Forecasts & Pricing: Based on their modelled market supply assumptions (uncommitted and unspecified new supply comes on as modelled) and base case demand projections (estimated CAGR of 14% to 2025), they forecast market oversupply of 13% in 2018 (38kt LCE) and 14% in 2019 (43kt LCE) see Figure 2 & 3 below. That said, they also forecast the market to swing back to balance/deficit by 2021, and by 2025, estimate that an additional 510kt (above 2015 supply estimates of 176kt LCE) of LCE production is required to meet the modelled demand estimates. Figure 91 also illustrates their bull case demand projections, which assumes an 8% annual increase in demand over their base case projections. Under this scenario, which assumes no change to the supply assumptions, they estimate a peak market surplus of 25kt LCE in 2019, and a market deficit in 7 out of 10 years to 2025. However, with their research indicating there are at least 18 advanced projects globally representing a potential ~400kt of new supply that could potentially be brought on stream within 5-6 years, they would expect in reality that any deficits may be much less severe. Under our modelled bear case scenario (assumes 8% less demand versus our base case), they estimate that the market would remain in constant oversupply over our forecast period, with peak oversupply of 29% in 2019, and a surplus of 9% in 2025.
Therefore, based on their supply/demand modelling, they forecast lithium carbonate prices to rise from US$6,000/t in 2015 to US$10,500/t in 2025, with spodumene concentrate prices expected to experience a similar increase from US$450/t in 2015 to US$725/t in 2025. Under their bull case demand scenario, they forecast lithium carbonate prices to rise to US$12,000/t and spodumene concentrate to US$870/t by 2025.
Pegmatite ores containing spodumene always contain several other minerals such as mica, feldspar, quartz, and iron and other silicates that have a tendency to concentrate with the spodumene. Weathering and surface oxidation of the rock also give rise to alteration products that interfere with flotation.
The reagent combination, to be most effective, should beworked out for each deposit by laboratory tests and pilot-plant treatment. The following combination, for a North Carolinadeposit, involves two steps of flotation.
Gangue minerals such as mica, feldspar, and quartz are first floated after grinding the ore and de-sliming by treatment with a cationic collector in alkaline circuit, and with starch or dextrine, to depress spodumene and iron minerals. The iron minerals are then removed by flotation in acid circuit with sodium resinate as collector and hydrofluoric acid as an inhibitor for the spodumene, which is thus concentrated in the tailing product.
The Morenci mill expansion project, which achieved full rates in second-quarter 2015, expanded mill capacity from 50,000 metric tons of ore per day to approximately 115,000 metric tons of ore per day, which results in incremental annual production of approximately 225 million pounds of copper and an improvement in Morenci's cost structure.
The Morenci mine is a porphyry copper deposit that has oxide, secondary sulfide mineralization, and primary sulfide mineralization. The predominant oxide copper mineral is chrysocolla. Chalcocite is the most important secondary copper sulfide mineral and chalcopyrite the dominant primary copper sulfide.
The Morenci operation consists of two concentrators capable of milling 115,000 metric tons of ore per day (mtd), which produce copper and molybdenum concentrate; a 68,000 mtd, crushed-ore leach pad and stacking system; a low-grade run-of-mine (ROM) leaching system; four SX plants; and three EW tank houses that produce copper cathode. Total EW tank house capacity is approximately 900 million pounds of copper per year. Morencis available mining fleet consists of one hundred and twenty-six 236-metric ton haul trucks loaded by 13 shovels with bucket sizes ranging from 47 to 57 cubic meters, which are capable of moving an average of 815,000 metric tons of material per day.
Phelps Dodge & Company invested $50,000 in the property in 1881, marking the New York mercantiles first venture into mining. Through acquisition, Phelps Dodge & Company consolidated all mining operations in the district by 1921.
Initially underground, Morenci transitioned to open-pit mining beginning in 1937. The operation nearly doubled its production capacity during World War II at the urging of the U.S. government to meet wartime needs. Morencis first SX/EW plant was commissioned in 1987. Once home to two smelters, the last smelter ceased operation in 1984. Both have been demolished and reclaimed.
72% - Freeport-McMoRan Inc.(undivided interest);15% - Sumitomo Metal Mining Arizona Inc. (SMMAzis owned 80% by Sumitomo Metal Mining Co. Ltd. (SMM) and 20% by Sumitomo Corporation); and13% -SMM Morenci Inc. (fully owned by SMM)
Bagdad is home to the worlds first commercial-scale concentrate leach processing facility (2003) and one of the longest continuously operating solution extraction/electrowinning (SX/EW) plants in the world (1970). An unincorporated community, Bagdad is one of two FCX company towns; the other is Morenci, Arizona.
The Bagdad mine is a porphyry copper deposit containing both sulfide and oxide mineralization. Chalcopyrite and molybdenite are the dominant primary sulfides and are the primary economic minerals in the mine. Chalcocite is the most common secondary copper sulfide mineral and the predominant oxide copper minerals are chrysocolla, malachite and azurite.
The Bagdad operation consists of a 75,000 metric ton-per-day concentrator that produces copper and molybdenum concentrate, an SX/EW plant that can produce up to 32 million pounds per year of copper cathode from solution generated by low-grade stockpile leaching, and a pressure-leach plant to process molybdenum concentrate.
First claims staked in 1882. Property changed ownership numerous times through first half of 20th century. First mill began operation in 1928 to process ore from the underground mine. Transition to open-pit mining began in 1945. A $240 million expansion in 1973 included new haul trucks, shovels, nearly 400 housing units and concentrator.
The Sierrita mine is a porphyry copper deposit that has oxide and secondary sulfide mineralization, and primary sulfide mineralization. The predominant oxide copper minerals are malachite, azurite and chrysocolla. Chalcocite is the most important secondary copper sulfide mineral, and chalcopyrite and molybdenite are the dominant primary sulfides.
The Sierrita operation includes a 100,000 metric ton-per-day concentrator that produces copper and molybdenum concentrate. Sierrita also produces copper from a ROM oxide-leaching system. Cathode copper is plated at the Twin Buttes EW facility, which has a design capacity of approximately 50 million pounds of copper per year. The Sierrita operation also has molybdenum facilities consisting of a leaching circuit, two molybdenum roasters and a packaging facility. The molybdenum facilities process molybdenum concentrate produced by Sierrita, from our other mines and from third-party sources.
First claims recorded in 1895. First worked as an underground mine beginning in 1907; open-pit development began in 1957. In 2009, FCX purchased the Twin Buttes copper mine, which ceased operations in 1994 and is adjacent to the Sierrita mine. The purchase provides significant synergies in the Sierrita minerals district, including the potential for expanded mining activities and access to material that can be used for Sierrita tailings and stockpile reclamation purposes.
The Miami mine is a porphyry copper deposit that has leachable oxide and secondary sulfide mineralization. The predominant oxide copper minerals are chrysocolla, copper-bearing clays, malachite and azurite. Chalcocite and covellite are the most important secondary copper sulfide minerals.
Since about 1915, the Miami mining operation had processed copper ore using both flotation and leaching technologies. The design capacity of the SX/EW plant is 200 million pounds of copper per year. Miami is no longer mining ore, but currently produces copper through leaching material already placed on stockpiles, which is expected to continue until 2023.
The first prospecting expeditions visited the area in the 1860s. Copper was mined underground until after World War II, when the first open-pit mining began. Miami was among the first to employ vat leaching (1926) and precipitation plants to recover oxide minerals. It did this in conjunction with its flotation concentrator, which processed sulfide minerals. The plants smelter was modernized in 1974 to meet Clean Air Act standards and further modernized and expanded in 1992. The success of an SX/EW plant commissioned in 1979 led to the demise of vat leaching by the mid-1980s and ultimately the concentrator in 1986. The rod mill was commissioned in 1966 and the refinery in 1993 (the refinery was permanently closed in 2005).
The Miami smelter processes copper concentrate primarily from FCXs Arizona copper mines. In addition, because sulphuric acid is a by-product of smelting concentrates, the Miami smelter is also the most significant source of sulphuric acid for FCXs North America leaching operations. Miami is the only smelter in the United States to achieve International Organization for Standardization (ISO) 9001:2000 certification. In addition to copper concentrates, the smelter also recycles inorganic metal-bearing waste typically produced by high technology industries, extending the useful life of valuable metals and reducing disposal of metal-bearing waste in landfills. Copper and other precious metals are extracted during this process.
The Safford mine includes two copper deposits that have oxide mineralization overlaying primary copper sulfide mineralization. The predominant oxide copper minerals are chrysocolla and copper-bearing iron oxides with the predominant copper sulfide material being chalcopyrite.
The property is a mine-for-leach project and produces copper cathode. The operation consists of two open pits feeding a crushing facility with a capacity of 103,000 metric tons per day. The crushed ore is delivered to leach pads by a series of overland and portable conveyors. Leach solutions feed a SX/EW facility with a capacity of 240 million pounds of copper per year. A sulfur burner plant is also in operation at Safford, providing a cost-effective source of sulphuric acid used in SX/EW operations.
The historic Chino mine was among the first low-grade, open-pit copper mines in the world. During 2011, mining and milling activities were restarted at the Chino mine. In April 2020, operations at Chino were suspended to address COVID-19 concerns. A review of options for restarting Chino operations was completed in the second half of 2020. In January 2021, FCX restarted mining activities at the Chino mine at a reduced rate of approximately 100 million pounds of copper per year.
The Chino mine is a porphyry copper deposit with adjacent copper skarn deposits. There is leachable oxide, secondary sulfide and millable primary sulfide mineralization. The predominant oxide copper mineral is chrysocolla. Chalcocite is the most important secondary copper sulfide mineral, and chalcopyrite and molybdenite the dominant primary sulfides.
The Chino operation consists of a 36,000 metric ton-per-day concentrator that produces copper and molybdenum concentrate, and a 150 million pound-per-year SX/EW plant that produces copper cathode from solution generated by ROM leaching. The available mining fleet consists of thirty-five 240-metric ton haul trucks loaded by four shovels with bucket sizes ranging from 31 to 48 cubic meters, which are capable of moving an average of 235,000 metric tons of material per day.
Originally mined by Native Americans and later by Spaniards. The open-pit mine began production in 1910. The original concentrator went into operation in 1911, but was replaced by a new facility in 1982. A smelter was commissioned in 1939 and was modernized in 1985 to increase capacity and achieve compliance with the Clean Air Act. In 2005, the smelter was permanently closed.
Prior to 1860, Native Americans mined turquoise at the site. Freeport-McMoRan Corporation (formerly Phelps Dodge Corporation) acquired mining claims in the area from 1909 to 1916, and began concentrating ore produced from large-scale underground mining in 1916. Operations ended in 1921. The property returned to operation as an open pit in 1967, with copper production from a concentrator. The SX/EW facility was commissioned in 1984. Tyrones concentrator suspended operations in 1992 when the property made the transition to SX/EW production.
The Henderson mill site is located 15 miles west of the mine. The mine and the mill are connected by the world's largest conveyor of its kind: a 10-mile conveyor tunnel under the Continental Divide and an additional five-mile surface conveyor.
The Henderson operation consists of a large block-cave underground mining complex feeding a concentrator with a current capacity of approximately 32,000 metric tons per day. Henderson has the capacity to produce approximately 35 million pounds of molybdenum per year. In response to market conditions, the Henderson molybdenum mine has operated at reduced rates since 2015.
In North America, FCX operates seven open-pit copper mines Morenci, Bagdad, Safford, Sierrita and Miami in Arizona, and Chino and Tyrone in New Mexico; and two molybdenum mines Henderson and Climax in Colorado. Molybdenum concentrate, gold and silver are also produced by certain of FCXs North America copper mines.
FCXs Lone Star project located near its Safford operation in Arizona is substantially complete and on track to produce approximately 200 million pounds of copper per year beginning in the second half of 2020.
FCX has significant undeveloped reserves and resources in North America and a portfolio of potential long-term development projects. Future investments are dependent on market conditions and will be undertaken based on the results of economic and technical feasibility studies, including the incorporation of innovation initiatives to reduce capital intensity.
This story of Dalzell has been provided by Mr Thomas Gorman of Dalzell Steel Works, stores department. It was compiled with photographs for the millennium in 2000 to preserve some of the history of Dalzell Steel Works for its present workforce. I have separated out the photographs for inclusion with others of Dalzell Steelworks on the website (see the button above). I have also added a few minor details to the text from my own researches.
Dalzell steelworks is located on the north east of a ridge separating the River Clyde from the South Calder River, within the burgh of Motherwell. It takes its name from the church parish of Dalzell. The name has many spellings Dalvell, Dalzyall, Daliel, Dalyell. Local pronunciation is De-ell. The steelworks are located on the Roman road of Watling Street, which runs from London to the Antonine Wall.
In 1791 the population of Dalzell Parish was 478. In 1836 a coal pit was opened. In 1841 the population was 1,457, of whom 726 were mostly weavers. By 1865 the population had increased to 4,261. However the industrial history of Motherwell dates from 1871 and the arrival of David Colville.
David Colville was born in 1813 in Campbeltown on the Mull of Kintyre. He started work in his fathers coasting vessel business. Then, in the 1840s he set up as a provisions merchant, in mainly tea and coffee, at the Trongate in Glasgow. However, he became interested in the thriving malleable iron industry and sought out an experienced partner. This he found in Thomas Gray, the manager of an iron works at Coatbridge. In 1861 they set up as joint-partners in the firm of Colville & Gray, at the Clifton Iron Works at Coatbridge. By 1870 there were disagreements and the partnership was dissolved. As Thomas Gray, with other financial backing, outbid David Colville for sole ownership of the works, David Colville, now aged 57, determined to use the proceedings of the sale to set up another malleable ironworks, assisted by his sons, John and Archibald. John was born in 1852, and had gained experience of Iron manufacture at the Clifton Iron Works. Archibald, was born 1854, and received commercial training in Glasgow.
It was difficult to find another suitable site in the heavily industrialised Coatbridge area and eventually David Colville was offered ten acres of land at Motherwell, with further room for expansion, by the Hamiltons of Dalzell. The site was beside the Clydesdale Junction of the Caledonian Railway and near the River Calder. On the 17th of February 1871, work began on the foundations for the Dalzell Iron Works.
By spring 1872, the Dalzell Works was practically complete and ready to go into production. Although it was a modest beginning, the works were larger than most Coatbridge malleable iron works, with: twenty Pudding Furnaces; two ball furnaces; one 18 Mill; one 12 Mill. The Pudding Furnaces started work on the 18th of March 1872, and the Mills started rolling on the 4th of April 1872; employing a total of two hundred men.
Although there were some early difficulties, the plant became increasingly successful, soon the quality of the Iron products gained a high reputation, and when disaster befell the Tay Bridge in December 1879, the contract for the supply of Iron Bars for a new bridge was secured by Dalzell.
The next important step taken at Dalzell was to begin the manufacture of Steel. Mr. David Colville, Junior, who had gained important first hand experience of the process involved in Steel production at Hallside steel works, in Newton, with the Steel Company of Scotland, Ltd. was the person most associated with this advancement and a further ten acres of ground alongside the existing Dalzell Iron Works was acquired.
A further five Siemens Open Hearth Furnaces, each with ten tons capacity, were erected. At the same time a Plate Mill, Shearing Plant and a Steam Hammer were installed; so the works could undertake the manufacture of both Ship and Boiler Plates. The new Steel Works started rolling steel plates in 1880, and thanks to Mr. David Colville, Junior, was an immediate success. Dalzell Steel was soon known for quality Steel throughout the world, and the production of Steel became the priority within the plant.
The works comprise thirty-two Siemens gas producers, with large wrought-iron over- head conducting tubes for the gas. One main lends to the melting department and another to the reheating furnace of the mill department. The melting shop contains four 12-ton Siemens steel melting furnaces, capable of producing 500 tons of steel ingots weekly, and one accessory-combined sand and manganese furnace.
The ingots are handed over to the mill department by two steam cranes, capable of lifting 6 and 10 tons respectively, made by Mr Grieve, Motherwell. The ingots are then reheated in two large gas furnaces, and reduced from 14 inches thick to slabs of four or five inches in thickness by a powerful steam hammer, made by Messrs R Harvey and Co, Glasgow, the cylinder of which is 33 inches diameter, by 8ft stroke. The anvil consists of a huge iron casting weighing about 140 tons, mounted by a smaller one with a steel face - in all, weighing over 150 tons. The weight of tup, piston, and rod is 12 tons; and with a working steam pressure of 80lb per square inch, the hammer is capable of giving a blow considerably over 400 foot tons.
The slabs thus consolidated and cut into sizes suited for the plates required are again reheated in other three large Siemens gas furnaces and then passed through the plate mill. In a central position of the mill floor are placed a pair of powerful Ramsbottom reversing mill engines, made by Messrs Turnbull, Grant and Jack, Canal Basin Foundry. The cylinders are 40 inch diameter by 4ft 6in, worked with 80lb of steam. The engines are fitted with the Allan link motion, and are placed under the driver's easy control by means of steam and cateract reversing cylinders. On the right hand side of the driver is placed the plate mill, with two pairs of rolls 8 ft. long by 28 in. diameter, the one pair being chilled, the other grain, and is capable of rolling plates up to 93 in. in width, by almost any length and thickness. On the left hand side is placed a 27inch bar mill consisting of three pairs of rolls, and capable of rolling the heaviest sections of angle, bars, bulb, T, beams &c . Both mills are from the workshops of Messrs. Turnbull, Grant, and Jack, and like the engines are of the most massive proportions throughout, the forgings and gearing being almost wholly of Siemens steel.
The entire plant, for design and workmanship, is an excellent example of the most modern rolling mill practice, and the performance is proving highly satisfactory. The machine for shearing the plates to the exact dimensions required is also of a massive and powerful description, made by Messrs. Turnbull, Grant, and Jack. The steel shearing blades are 10 ft. in length with a stroke of 12 in. and capable of shearing steel plates 1 1/2 in. in thickness by 7 ft. broad through at one stroke. The machine has also combined a scrap shears, and is driven by a combined steam engine of 16 in. cylinders by 20 in. stroke, working with 80 lb. steam. The same company have also made for the bar mill side a powerful hot sawing machine, driven by a pair of 8 in. cylinder engines capable of cross sawing to the lengths required the heaviest class of billets, bars, and beams.
There are four boilers for supplying steam to the various machinery of combined flue and multitubular type, constructed entirely of Siemens steel by Messrs. A. and W. Smith and Co Eglinton Engine Works, and are worked at a pressure of 80lb.The chemical and mechanical testing houses adjoin the works. The testing machine made by Messrs. Joshua Buckston and Co., Leeds, is capable of testing up to 50 tons on the piece, the whole operation being entirely done by steam power.
The roofing covers an area of over 5,490 square yards, is constructed entirely of wrought iron with galvanised corrugated sheet iron covering, and supported on cast iron columns. The works will occupy about fourteen acres of ground.
Here is a an example of the reputation Dalzell achieved at that time . It is about a Niagra Steamer, built in 1887 ..."the Cibola is a paddle steamship ......built throughout of Dalzell steel which is the best known to shipbuilders, the plates being sent out from Scotland by the Dalzell Co., each being warranted and having the manufacturer's trade mark stamped thereon" . http://www.hhpl.on.ca/Greatlakes/Documents/Robert2/default.asp?ID=c012
With Dalzells reputation for quality Steel, a strong connection with America had been established; (the first Steel Plates rolled in the United States were made from slabs supplied from Dalzell for the Lukens Steel Company) and in Europe, Germany constructed its first Atlantic Liner entirely of Dalzell Steel. In July 1895, the firm converted to a Private Limited Company, with Mr. David Colville, Senior, as chairman until his death in 1897. He was succeeded by Mr. John Colville, who was also a member of Parliament for North East Lanark until his death in 1901.
In about 1884 the first experiments were made with electric lighting of Dalzell works. The current was from a small generator, driven by the bar mill saw engine; a somewhat humble beginning for electric power in the works. This first experience was not very successful, as the vibration caused by the large steam hammers then in operation interfered seriously with the lighting arrangements, and the lamps were discarded for a period.
With Mr. Archibald Colville now Chairman, Dalzell continued to grow and prosper, and by 1912 a large extension to the plant was begun, this was completed by the summer of 1914, by this time 2,800 men were employed in the works, which consisted of:
For the next four years, practically all that was produced at Dalzell Works was for War material. With the new Cogging Mill rolling Shell Bars, and Forging Blooms, two additional Open Hearth Furnaces were built in 1915.
The three plate mills were busy rolling up to 4,000 - tons per week, High Tensile, and other qualities of steel plate which were used in all classes of Warship, including the Tiger, Barham, Renown, and for Destroyers, Submarines, Mine sweepers etc.
By 1918, over 500 - tons of Bullet Proof Plates for Tanks were rolled per week, and arrangements made for these plates to be made into complete sets, ready to assemble. Buildings were erected, machines purchased and three shooting ranges built for testing these plates.
Due to the massive demand for Steel at this time, the Companys output had grown to over 467,700 ( Steel Ingot - Tons per annum ) and Colvilles had expanded to include the Works of Clydebridge, Fullwood Foundry, and Glengarnock.
The extra work and responsibilities undertaken by Mr. Archibald and Mr. David Colville began to effect their health, and on the 16th of October 1916, Mr. David Colville died, and only two months later, after a brief illness, Mr. Archibald, died on the 11th of December 1916.
Mr. John Craig succeeded Mr. Archibald Colville in the Chairmanship of the company. Mr. Craig, employed from 1888, was made a director of the company in 1910, in 1918 he received an O.B.E, from King George V, for his services to the nation during the War years. As well as bringing Clydebridge, Fullwood and Glengarnock Works under the control of Colvilles, the Company also purchased the firm of Archibald Russel. Ltd.
At that time they owned twenty - four pits, nineteen in Lanarkshire and five in Stirlingshire which included: Ferniegair; Ross (Hamilton); Tannochside (Uddingston); Murdostoun (Cleland); as well as the Polmaise Pits in Stirlingshire.
These Pits employed a total of 6,500 men, and produced approximately One Million and a Quarter tons per annum. They also owned nearly four thousand railway wagons, the repair and upkeep of which a Wagon Shop, equipped the most modern machinery at the time, had been built at Whitehill, Hamilton.
The Gartcosh Sheet and Galvanising Works, and Milwood Works was acquired from Smith & McLean, Ltd. which brought a total of nine Sheet Mills, one Bar Mill, and fourteen Pudding Furnaces under the control of the Colville Company. Mavisbank Works, was equipped for Galvanising work of all descriptions, and the plant was one of the most up-to-date in Britain at the time.
Altogether, the Company and their allied concerns employed about 18,000 workers, including approximately 5,000 at Dalzell, 3,000 at Glengarnock, 2,000 at Clydebridge, 6,500 at the Collieries and 1,500 at Smith & McLean. Ltd.
In the same year, Mr. David & Mr. Norman Colville, in memory of their late fathers, purchased the Jerveston Estate of 75 acres and the Mansion House, near Motherwell for the Workers of Dalzell for Welfare purposes, and which stands a Golf Course and Social Club.
Another development at this time was the organisation of the Colvilles Music Festival which was open to all Colville employees. The first Festival held in Motherwell was in April 1921, and various Male and Mixed Voice Choirs, Brass and Pipe Bands, etc. formed from the Works and Collieries took part.
In January 1920, the first Company Magazine was produced, the Colvilles Magazine was a monthly journal issued to employees at a price of 2d, and the contents, were often contributed by the workers themselves.
By 1920, Colvilles had been transformed and re-equipped before the recession of the twenties had begun, obviously this was a very difficult time, not only for Dalzell and the other steel plants, but for every industry in the country.
By 1931, with the country still suffering from the effects of the recession, Colvilles and Sons was converted to a private limited company, from then the company grew steadily, and in 1934 the public was given the chance to invest in Colvilles, and again in 1936 when the ordinary shares were offered to the public. At this time The Lanarkshire Steel Works and The Steel Company of Scotland were added to the Colville Group.
In 1937, the Dalzell Bar and Rod Mill was constructed, and was the first mill in the country to incorporate continuous rolling, also in 1937, the decision was taken to scrap and rebuild the Clyde Iron Works with new coke ovens and blast furnaces. A new bridge was constructed over the river Clyde to link the Iron Works and Clydebridge Works, thus producing the largest integrated plant in the UK at the time.
As well as shipbuilding, Dalzell was also known for rolling plate used in the fabrication of both ship and land based boilers, and because of the requirements of this type of work Dalzell was in the special position to offer, probably the largest plates in Britain at that time.
With the outbreak of the Second World War, Colvilles was once again put at the disposal of the War Office. Obviously the need for steel was vital at this time, and soon the Colville mills were breaking all previous tonnage records to meet that demand.
With the Cogging Mill producing Shell Bars and the Plate Mills supplying the Clyde Shipyards with High Tensile steel used to build ships, such as the Battleships Duke of York, Howe and the Vanguard. as well as the Aircraft Carriers Theseus and Implacable and other ships including Cruisers, Destroyers and Submarines etc.
Like many other industries at that time, the steelworks having lost the services of many experienced men when they enlisted in the Armed Forces, were called to find alternative personnel, personnel that came in the form of the Wives and Girlfriends of the steelworkers.
In 1946, Sir John and Lady Craig donated the Craig War Memorial Home to the men and women who made the supreme sacrifice and as a convalescent and rehabilitation centre for those returning with injury and sickness, as well as the home, two acres of ground was also acquired at Skelmorlie on the west coast of Scotland.
Colvilles introduced Colclad Steel to the companys range of special steels, the name Colclad was registered to the Colvilles company in 1947 for its special bonding of different types of steels, and though no longer produced at Dalzell, the name Colclad still refers to this type of composite steel.
1953 saw major changes to the Light Section Mill. The original LSM having been in service since almost the inception of Dalzell, was rebuilt with new mills being installed which enabled Dalzell to increase its capacity and roll a wider range of sections.
In July 1954, Colvilles received the sanction to proceed with its plan to construct the new Ravenscraig works Over 4,000,000 cubic yards of earth had to be excavated to level the site prior to the construction of the plant.
After three years of construction work the first stage of the new Ravenscraig plant, the coke oven, blast furnace and melting shop was completed and in June 1957 the coke oven was lit for the very first time. The next stage, a second blast furnace, a duplicate set of coke ovens and a new slabbing mill that would eventually supply Dalzells heavy plate mill, as well as the Ravenscraig strip mill.
All this investment had been planned during a difficult time within the steel industry, output had been reduced by more than 30% in some mills in 1956/57, and it was not until late 1958 that demand began to recover. Its to managements credit and forward planning that the investment made during this time was soon rewarded.
One of the first indications the market was recovering was the order for 2,000-tons of Colvilles steel rod, that was used to make reinforced concrete approaches and portals for the Clyde Tunnel, with its two tunnels each 29 ft. diameter and 2,250 ft. long, that accommodated the two twin-lane carriage ways.
At this time Dalzell was going through some major structural changes, with a new Test House building being constructed. The two storey building would eventually house the most modern testing equipment available at that time.
The most significant change in the Dalzell plant was the demolition of No. 3 Melting Shop to make way for the new bays that would house the new reheating furnaces and eventually the 4-high plate mill. After the bays were completed, Colvilles first constructed a continuous pusher type furnace as well as No. 2 and No. 3 elpits which were to supply the increased demand expected from the new mill. Later the larger No.4 and No.5 SAS pits, capable of handling slabs up to 50 tons in weight were added to the elpits to handle the increased demands of the new mill.
The new Slabbing mill at Ravenscraig started production in 1962, the 2-High Reversing Mill with rolls 50 inch diameter and 138 inch long was capable of rolling larger ingots than any other mill of its type at that time.
The new mill, rolling slabs for both Dalzell and the new Strip Mill at Ravenscraig was soon producing over 1,250,000 tons per annum, and had the capacity to increase production to 2,000,000 tons a year.
In 1963, an order for a total of 9,500 tons of steel was placed with Colvilles for the new Tay Road Bridge. By 1964 Two thousand tons had already gone into the piling of the new bridge. By 1966, a further 2,500 tons of high-yield plate for the box girders and Five thousand tons of reinforcing bars were used in the concrete work. The bridge, 7,300 ft long, carries four lanes of traffic, and gradually rising in high from 30 ft. to 125 ft. above sea level before it reaches the Fife shore.
With the upturn in market conditions orders from the shipyards soon increased, and continuing Colvilles long association with the Clydeside yards the Dalzell and Clydebridge plate mills was rolling large quantities of steel plate to be used in the construction of one of the most impressive ships ever built. The John Brown Engineering Co. Ltd. was building a new Cunard Liner at their yard on the Clyde. The new passenger ship when completed was named by Her Majesty the Queen, and launched into the River Clyde in September 1967. The Queen Elizabeth 2 was the last great liner to be built at the John Browns shipyard, and its unlikely that ships of this size and type, will ever be built on the Clyde again.
In 1967, Dalzell saw the installation of a new Heavy Plate Flattening Press at the plant. Delivery of the 2,000 ton Press caused some problems for the town of Motherwell, with roads being closed for some time while this large load slowly made its way to the Dalzell plant.
Also in 1967, Dalzell and the rest of the Colvilles works were nationalised, through the then new Labour Governments policy that all major steel producing companies should be brought under state control.
The Colvilles group consisted of Dalzell, Ravenscraig, Gartcosh, Clydebridge, Clyde Iron, Glengarnock, Lanarkshire, Mavisbank and Port Glasgow Galvanising, Craigneuk, Hallside, Fullwood and Hamilton Foundries, Etna Iron & Steel and others.
Colvilles and Dalzell had grown into one of the most successful steel companies in the world under the guidance of Mr. David Colville senior, his sons David and Archibald, Sir John Craig and Sir Andrew McCance, it is because of their professionalism and expertise that Scotland had such a successful steel industry.
Although Dalzell had changed ownership, the plans for Dalzells new 4-high Plate Mill had been under way for sometime, bays were now being constructed to house both the new mill and reheating furnaces. This decision by the Colvilles board to build one of the largest and, after incorporating some major design changes, most advanced heavy plate mills in the world, has ensured that Dalzell is still at the forefront in today's heavy plate market.
The mill described at the time as a World Beater was designed by Moeller and Neumann to the recommendations set out by our own Technical and Engineering Department. These recommendations included pre-stressing, roll bending and computer control, that made the Dalzell mill the first heavy plate mill to incorporate such unique features, which along with work rolls of 4.6 metres in length and back-up rolls 1.8 metre in diameter gave the Dalzell Plate Mill the ability to roll a variety of plate sizes, from 6 mm up to 375 mm thick, that enables Dalzell to produce some of the largest plates of quality steel in the world.
To meet this demand, and the demand for Strip Steel from the Ravenscraig Plant saw the British Steel Corporation invest in an Ore Terminal at Hunterson on the West Coast of Scotland, the Hunterson Port, a natural deep water port that was capable of handling the large Tankers required to supply the Ravenscraig blast furnaces.
With Dalzell now part of the British Steel Corporation, the plant over the next few years underwent some major changes, which under the terms of the B.S.C rationalisation plan, included the closure of the Bar and Rod Mill, Light Section Mill, No. 4 Bar Mill, No. 4 Melting Shop and eventually the Colclad Department. These changes, designed to transfer production from the older mills to more modern and efficient mills down south saw a more streamlined and profitable Dalzell. With a heavy plate mill capable of producing some of the largest plates and with a reputation for quality steel known throughout the world, Dalzells plate mill was soon one of the major suppliers of plate for the offshore Oil Rigs, which obviously demanded quality plate to survive the severe conditions of the North Sea.
Now that the Dalzell plant only supplies the plate market, continuous modernisation of the mill enables the plant to stay at the leading edge for quality and special steel plates, for which its been known for generations.
With the streamlining of the Dalzell Works, which saw the eventual closure of the No. 4 Melting shop, Motherwell was now reliant on the Ravenscraig plant to keep its steel making tradition going. Investment in the Ravenscraig plant continued throughout the 1970s with a 67 million Furnace and a 30 million Sinter plant, that was opened by the then Minister of State Mr. Gregor Mackenzie.
In the 1980s with the B.S.C suffering crippling loses, the then Chairman Mr. Ian Macgregor stated that the Ravensgraig Works future was uncertain when he announced massive redundancies at the plant, and that closure of the Gartcosh Works would take place in 1986.
Dalzells plate mill continued to be one of the major suppliers of plate for the Oil Industry in the North Sea, and by 1986 we had produced over 1,000,000 tonnes of plate used in the construction of offshore Rigs and Platforms.
In 1987 the plate mill implemented an Automatic Gauge Control (A.G.C) system which has greatly improved plate flatness along the full length of the plate. Also in 1987 a new de-scaling system was installed at the mill, incorporating 46 specially designed nozzles each delivering high pressure water up to 250 litres per second.
The streamlining of the company continued with the announcement in 1990 of the phased closure of the Ravenscraig plant. Over the next two years a gradual reduction in the workforce ended on the 27th of June 1992, when the final 1,220 workers left the Ravenscraig plant for the last time, and with them went a long tradition of Steel making in Scotland.
Work began on removing the Ravenscraig site almost immediately, most of the plant being dismantled and transferred to other plants within British Steel, with some plant going as far a field as America. With the removal of all reusable plant, work began on the demolition of the remainder of the works, a task that would take more than four years to complete, and would be concluded with the demolition of the Ravenscraig towers on the 28th of July 1996.
With the Ravenscraig closed the Dalzell plate mill is now supplied with slabs from the Scunthorpe and Teesside works in the North of England, these slabs were transferred by road until recently when a new rail link into Dalzell was built.
British Steel entered into an agreement with Nippon Steel of Japan during the early 1990s to enable both companies to benefit from mutual experience and practices to try and achieve better product quality. Because of this the N.S.C task team was set up within Dalzell in the summer of 1997 to liaise with our colleagues at the Oita Plant in Japan.
Three teams were formed from a cross section of the Dalzell work force which have visited the Oita plant, The Japanese have also visited the Dalzell plant on three occasions to date, and a strong working and social relationship has developed between the Dalzell and Oita personnel.
Over many years, both British Steel and Dalzell has strived to minimise the environmental impact associated with the steel making industry, this commitment has continued with Dalzells ISO 14001 monitoring programme which has helped reduce pollution from the Dalzell works to near zero levels, and the programme has now been implemented by most other British Steel plants.
Recent environment control measures taken at Dalzell includes the upgrading of the water treatment system to include interceptors in which a series of booms act as barriers to any oil discharged from the works, that allows most of the water to be recycled back to the high tank to be used again, any excess water is now clean enough to be discharged back into The South Calder River.
In 1999, Dalzell re-entered the Clad Plate market some twenty years after the closure of the Colclad Department. Dalzell first produced clad plate in 1947 using a technique which became known throughout the world as Colclad steel.
With advancement in technology Dalzell now uses an Explosive Bonding technique to produce the composite steel, bonding stainless steel to carbon steel before rolling to the required size. This important market mainly supplies the Oil, Gas and Chemical industries, supplying steel for reactors, vessels and boilers etc.
Dalzells reputation for quality, helped to secure an order for steel plate used in a fifteen kilometre civil engineering project that will link two European countries. By August 1998, the Dalzell and Scunthorpe plate mills had supplied over 44,000 tonnes of steel used in the construction of the 49 approach spans, each 140 metres long, that will make the Oresund Fixed Link the longest bridge of its kind in the world. When completed in the year 2000, the four lane highway and two railway lines will span almost eight kilometres and link the two countries of Denmark and Sweden.
At Dalzell, both management and unions have been in negotiations throughout the year with the view to change traditional working practices and implement a new Team Working principle, where the boundaries between Craft and Production are reduced with the aim of increasing efficiency through training, which will ultimately maximise performance within the plant.
The 6th of October 1999, saw the two companies of British Steel. Plc. and the Dutch company Koninklijke Hoogovens merge, to become a major new metals company. The company now trading under the new name of CORUS, is also supported by the new style logo shown below.
The Dalzell success story can only be attributed to both management and employees professionalism and skill as well as the determination to succeed in todays competitive markets. With the support of our new company CORUS, Dalzell Works will continue to provide quality plate throughout the world, as we have done for nearly 130 years.
The oil-fired furnaces of No.3 shop were single uptake, twin lateral burner furnaces and were fired by heavy fuel oil; the producer gas-fired furnaces were post first World War, and both were charged by non-rotating ground chargers from pans set on bogies in front of the furnace.
The liquid steel was tapped from the furnace into single or double stoppered ladles (depending on ingot size and method of pouring) set on stands under a swivel launder. There were nine teeming locations available for pouring into permanent pits at ground level.
These ladles were handled by three 125-ton ladle cranes with auxiliary hoists of 30-ton capacity. also three 30-ton capacity service cranes were located between the ladle cranes to strip and set-up the pits.
The waste heat from the furnaces was utilised throughout the work, and any excess steam was passed to the Lanarkshire Steel Works steam system via a 10. inch diameter pipe approximately 2, 800 ft long.
The soaking pits were fired by producer gas supplied from two gas machines. the fuel for these machines were brought to a coal handling plant in railway wagons that were side-tipped into a hopper, from there the coal was fed on to a conveyor belt which lifted it up to storage hoppers above the gas machines, some 395 ft. away. The soaking pits consisted of four regenerative type and six top-fired recuperative type, and all used rolling top covers operated by electric motors. the regenerative pits were designed and built by Colvilles personnel.
These pits were supplied with ingots from No.4 Melting Shop, either by wagon or a 10-ton overhead jib that transferred the ingots from the casting bay to the soaking bay, also in the soaking bay were two 5-ton cranes with self-acting dogs as well as a stiff-mast crane to take the ingots from the soakers to a hydraulic-operated tilting chair at the end of the ingoing rack to the cogging mill.
The outgoing rack from the mill delivered the billet to the hydraulically operated shear, that had a blade pressure of 920-tons. The shear trimmed and cut the billets to length before being either, transferred the cooling bank for shipping to the LSM, or to a hot deseaming machine prior to being transferred to the Roughing and Finishing Stands where manipulators turned the bars between passes, these stands were serviced by a 30-ton overhead crane.
The finished bars were moved to the first of three rotary saws to be cut to length where they were either put into slow cooling pits, or continued to the billet shear that had a blade load of 450-tons, and could cut to a maximum of 5 inch square. from the shear the billets ran on to a skew rack that bunched the billets against a stopper, before running them on to the cooling bank.
In 1937, a Merchant Bar and Rod Mill was constructed, which was the first mill in Scotland to incorporate the continuous system of rolling, and was known as one of the most efficient mills of its type in Europe.
On a normal 7.1/2 hour shift, approximately 900 billets were rolled (the equivalent of one billet every 30 seconds) when lighter sections were rolled, the front end of the bar was being delivered to the cooling bank or the coilers before the rear end left the furnace.
The rod mill comprised of a billet storage yard, a seven-stand continuous roughing mill, a twelve-stand intermediate and finishing mill, rotary flying shears, a mechanical cooling bank, cold shearing equipment for straight lengths, three laying reels for rods and two pouring reels for bars. A hook type cooling conveyor for coiled material was also provided. this had a run-out of 1,100 ft. at the end of which the coils where cool enough for handling.
A 10-ton magnet crane was used to transfer the billets from rail wagons to the stock pile and then to the reheating furnace. The continuous reheating furnace was side charging and discharging type, the cold billet dropped to a feed bench on to roller tables and then to the furnace. the hot billet was then ejected from the furnace by a peel type pusher.
On leaving the furnace the heated billet passed between de-scaling rollers to the first of the six roughing stands, the rolls on each stand progressively increasing the length of the bar. after leaving the roughing mill the rolled billet was automatically looped after being caught by an operator and entered into the next stand, before being looped again after being caught by a second operator who entered it into the finishing stand, from there the rod was put onto reels or sheared to length by rotary blade saws before being stacked on the cooling bed.
The Light Section Mill was designed and constructed by the Colville technical and engineering staff to replace the two stand 18 inch reversing mill which had been in service almost since the inception of the company in 1871.
The mill commenced operation in September 1953, and rolled a wide variety of products, including joists, channels, tees, angles, hexagons, rounds, flats and a range of special sections. all of these products were rolled from billets supplied from the Bar Mill.
The billets were unloaded by a 10-ton magnet crane at the stockyard prior to being transferred to the furnace charging table. There they were re-heated by a oil-fired two zone continuous re-heating furnace before being discharged to the rack which took the billets to the 20 inch high reversing Cogging Mill equipped with manipulators and a special bobbin tilting device, this arrangement allowed up to 330 blooms to be worked through the mill in a 8 hour shift.
The finishing mill comprised of two stands, having three-high rolls, intermediate and finishing placed in line and driven by one motor. The middle roll was fixed and the top and bottom rolls had a screw adjustment. Special cradles were used to lift the top and middle rolls in and out, to set the mill bearings.
The Light Section Mill also had is own roll shop complete with three lathes, two of which were set to accommodate two mill rolls at the one time, the other older lathe was used for turning rollers for the straightening machines used within the LSM.
Colclad steels, in simple terms, consists of a four-tier composite ( or sandwich ) of two plates of cladding metal placed between two slightly larger plates and then welded, these slabs weighed up to ten tons and varied in thickness from four to twelve inches.
The composite slab was then transferred to the re-heating furnace and soaked for a long period before being rolled to the desired thickness. After rolling, the plates were heat treated before being transferred to the finishing department for shear or gas cutting.
When this operation was complete the two clad plates were separated (as shown in photograph) and then cut to size, before being flattened at the leveller, then pickled in acid solutions appropriate for that particular cladding alloy. finally, Ultrasonic Testing by an oscillograph, and Tensile Testing in our Test House completed the final check on the continuity of the bond before being dispatched.
The plant consisted of straightening, flattening and oxyplane gas cutting equipment for the plates and flats used in these units , together with automatic welding units used for fabrication of the sections.
The Beam Welding supplied these sections to the major shipbuilding yards of Scotland, Northern Ireland and the North East Coast of England, until changes in the design of these ships reduced the demand for these sections to the extent that the plant was no longer viable.
The slabs were passed through the wide rolls and finished down to the desired plate thickness if too wide for the adjacent rolls. All plates that were passed through the latter were finished there, after being roughed down in the wider rolls. Normally the mill produced plates from inch to 2 inch thick and up to 13 ft wide, but slabs plates considerably thicker could be equally well rolled.
The mill was driven by a twin tandem compound condensing steam engine, with cylinders 38.5 inch diameter and 55 inch diameter and 60 inch stroke. Steam at 200 psi passed to a steam accumulator, reaching the engine at 100psi.
The mill was eventually converted from steam driven power to an electric drive in 1955. The mill rolls were driven by a single armature DC shunt wound motor of 4,600 hp continuous output and 11,500 hp peak. The motor was driven by a Ward Leonard flywheel motor generator. The flywheel driving motor was a slip ring induction motor of 7,500 hp continuous and 15,000 hp peak.
Colvilles own Electrical Department and Technical Office installed an automatic device in 1954, that so impressed the then Chairman, Sir. Andrew McCanes, that in 1957 he ordered the whole mill to be made automatic.
The A.G.C cylinders are mounted under the bottom back-up roll chocks on either side of the mill, and are supplied with oil by two Rexroth pumps, with each cylinder pressurised to maintain the correct position or rolling force which is controlled by servo valves. The working pressure of the system is 4400 P.S.I causing a rolling load of 4000 tonnes per cylinder, these cylinders can also be used to implement (PVR) Plan View Rolling.
One of the major advantages of the Dalzell process control system, is that it has the facility for PVR. Dalzell is the only work in the U.K with this facility and is a technique developed to give straight edges and square corners during rolling.
The Dalzell plate mill has the facility to roll more than one plate at a time which allows us to roll plates at varying temperatures to keep the correct material properties, with the first plate rolled to given gauge and temperature it is then held by removing it from the roller table by means of a lifting rig which is operated by overhead crane, the other plate is then rolled until the first plate has cooled to the required temperature to achieve the best chemical properties, and whilst the first plate is finished the second is allowed to cool back on the rack until it reaches its correct temperature.
After leaving the plate mill the rolled plate, if over 120mm thick will be transferred to the lumb bank for either heat treatment or gas cutting. Plates under 120mm thick go through the hot leveller to ensure good flatness.
The Hot Leveller manufactured by Colvilles in 1942 is capable of handling a maximum width of rolled plate up to 4067 mm wide. from there, the plate will be routed for either normalising, slow cooling, gas cutting or for plates under 40 mm thick the cooling banks on the shears floor where they are marked and stamped before being transferred to the end-cut shears.
The End-Cut Shears, manufactured by Sack Ltd. was installed in 1955, trims the end of the plate by use of hydraulic blades to give a square finish. before proceeding to the Duel Side-Cut Shears which was installed in 1967 by Moeller Neumann.
The Side - Cut Shear acutely consists of two separate housings mounted on a common base, one is fixed the other is adjustable to trim plates from widths varying from 800 mm up to 4300 mm and is capable of handling plates up to 40 mm thick.
An important part of the plate finishing is the Plate Cutting Department, and in the 80s and early 90s both Dalzell and Clydebridge works invested in modern computerised cutting machines, capable of cutting any programmed shape from the plate.
These machines which runs on rails with a chassis supported by four wheels and has the cutting nozzles mounted on a guide rail, with three burner carriages and one marker carriage, each individually powered by its own gearbox.
Plates that require further treatment are sent a short distance away to our sister plant The Clydebridge Works, plate rolled at Dalzell that requires to be Quenched and Tempered are transported by road to the Cambuslang plant.
The Roller Pressure Quench was installed in 1974, and has been continually modernised and developed since then, the heat treatment facilities are amongst the most modern in Europe which is supported by the most up-to-date computerised tracking and monitoring system.
The process of Roller Quench and Temper gives the benefits of allowing steel with lower alloy content to be used in certain applications where a high alloy steel would normally be required, thus making it more readily weldable and allowing a wide range of strength levels to be produced.
The high strength to weight ratios produced by this process allows steel appropriate to the task to be used with a significant weight reduction, Abrazo steel will also have the benefit of being extremely wear resistant and will increase the life and reliability of components.
The slabs for the plate mill are now sent from the Scunthorpe Works by rail and received at our Slab Bay, where they are prepared before being transferred to the reheating furnaces where they are heated to the required temperature before being presented to the plate mill.
In 1959, a new reheating furnace was installed by Priest Furnaces, this was a 5 zone single line pusher type with a capacity of 76t/hour and handling slabs 2030 wide x 305 thick x 3900 in length and up to 18 tons in weight.
The Pusher Furnace which is still in use today is heated by 19 conventional type burners fuelled by natural gas (with gas oil as a standby option) that heats the slabs to a temperature of 1250.C prior to being delivered to the plate mill.
This modern system helps to control the delivery of slabs from the furnace to the mill at the correct time, keeping a monitoring control on temperature, soaking time, oxygen levels and withdrawal times.
Dalzell originally had two 12 ton slab hammers, each having a double acting steam cylinder, 33 inches diameter, with a stroke of 8 feet. The falling mass on its own had 96 tons of stored energy, but with steam at 80psi on the piston the stored energy was 336 ft tons. The ingots were manipulated manually with levers so the weights which could be handled were limited. The operation was also dangerous, as unless the levers were removed before the hammer struck their ends were liable to be violently thrown up, often with disastrous results to the men. To increase safety, and allow heavier ingots to be used, rolling mills, called Cogging Mills in the UK and Slabbing Mills in the USA, were introduced. The first in Great Britain at Blochairn Works in 1884.
The first cogging mill to be erected at Dalzell Works was started in 1895. It was a reversing mill having a single stand of housings, and was designed to handle ingots from 5 to 7 tons in weight. It had rolls 33 inches diameter in the body by 8 ft 6 inches long over the barrel, with an edging groove at each end. The mill was driven through gearing in the ratio of 2.52 to 1 by a pair of non-condensing horizontal engines having cylinders 44 ins diameter and a stroke of 60 inches. The steam pressure was 100 lbs per square inch, and the exhaust steam was led to heat accumulators in connection with the electric power stations.
About 1920 a heavier reversing two-high stand cogging mill, having 36 inch diameter rolls (later 42 inch and by 1944 44 inches) by 10 ft long was installed, capable of handling ingots up to 30 tons weight. In this case the racks and screw gear were electrically driven, the tilters and side guides being operated by hydraulic pressure as at the 33 inch mill.
These rolls were originally driven by a steam engine, but in 1933 the drive was converted to electric power, being and driven by a 19,000hp motor, weighing 326 tons, one of the largest single shaft mill motors in the world at that time. In 1944 the mill was reconstructed with 44 inch diameter rolls and the motor upgraded from 3 to 4 armatures, to produce a peak of 25,000 hp. The weight of the motor was then 420 tons, 220 tons of which was rotating.
The reheating furnace was a continuous bogie type, approximately 110 ft. long. the bogies covered the full length of the furnace each bogie was 9 ft. long and capable of handling ingots up to 33-tons in weight.
The hot shear mill was made by Davy Brothers, Ltd., of Sheffield, for the larger of the two Slab Cogging Mills at Dalzell Works. It was able to cut slabs 66 in wide by 18 in thick, or forging blooms of equivalent sectional area up to 27 in thick, and was considered to be the most powerful unit of its type in existence at that time.
With the increased demand for steel at Dalzell, a new Test House building was constructed in 1960s, the original building being to small to house the new machinery and testing equipment needed to confirm the quality of the steel produced at Dalzell, and that it met the standards required by the customer.
The Test pieces were cut from the plates as they passed through the finishing department and transferred to the Test House, once there, the tests were cut to length, centred and stamped prior to rough and finished turning on the lathes, before being popped on a 80 mm elongated test.
If the sample required a impact test, it was cut and stamped at the saw before being rough and finished milled prior to being sent to the impact machines to be tested, there was also four small re-heating furnaces within the test house to heat the sample to the required temperature if needed.
With the company's continuous efforts to reduce costs, the decision was taken to send all the Dalzells test samples to one main testing centre at British Steels Scunthorpe Works in England. Unfortunately, this resulted in the closure of the Dalzell Test House in July 1999.
The Metallurgical and Engineering development teams were based in the Technical Office. The metallurgical group was well equipped for research in the heat treatment and mechanical properties of steel. A large laboratory was used for rupture testing of steel, and a high frequency furnace was used in the development of new steels for engineering applications.
The Central Research Department was housed in the technical office until 1961. Then, because of the increase in technical staff that, then numbered over one hundred, the accommodation available became inadequate and was therefore moved to more spacious premises in meadow road. The new accommodation contained an office block with light laboratory and a separate building containing a workshop and a heavy laboratory. This was divided into divisions, Development, Metal Physics, Standards, Chemistry and General Metallurgical.
The Central Research also had a well-equipped workshop that, though committed to constructing apparatus and preparing tests specimens was also able to undertake the construction of working models, and prototype equipment.
In 1956, a small Training Centre was set up at the Mossend Engineering Works, at first the centre only catered for a dozen hand picked apprentices who were trained by one full-time instructor. As time went on, the school was expanded to 45 apprentices, who were trained by instructor Mr. John Kennedy and five assistants. This experiment proved to be a great success, so much so, that Colvilles decided to build and equip a new training centre and increase the training period from 6 months to 18 months.
Colvilles and Dalzell has a long tradition dating back to the very beginning of the company in which it encouraged employees and their families to participate in many social events, such as the employees annual Christmas Dance and Christmas Pantomime for the children as well as the children's outing to the coast, Car Club, Pipe Band, Male and Mixed Voice Choirs, The Ambulance Section and many others.
(also rod cell), a photoreceptor of the human and lower vertebrate eye. The rod cells respond to faint light. They and the cone cells are located in the outermost part of the retina. The cells consist of a basal synapse (connected with deeper-lying retinal cells), the nucleus, an internal segment containing ergastoplasm, the myoid (a contractile element of the rod cells), the ellipsoid (a mass of mitochondria), and an external segment made up of disks. A connective fiber with nine pairs of threads typical of cilia and departing from a pair of centrioles unites the internal and external segments. The disks of the outer segment, which are composed partly of visual pigment, are formed by an invagination of the cytoplasmic membrane. At the retinal periphery, there are more rod cells than cone cells. The retinas of nocturnal and crepuscular animals contain only rods.
in the theory of oscillations, an elastic solid body whose length greatly exceeds its transverse dimensions. When a rod is excited, for example, by an impact, free oscillations arise in the rod. The oscillatory displacements of the particles of the rod may be directed either along the rods axislongitudinal oscillationsor perpendicular to the axistorsional and flexural oscillations. For torsional oscillations, any cross section of the rod is twisted with respect to an adjacent cross section. For flexural oscillations, the points of the axis of the rod are displaced in a transverse direction, and fibers parallel to and lying on various sides of the axis undergo tensile and compressive strains.
Any oscillation of a rod may be represented as the sum of the simplest sinusoidals of the various types of natural oscillations in the rod. The frequencies f of the oscillations depend on the length l of the rod, the density p of the material, the shape and area S of the cross section, the elastic reaction to the given type of deformation, and the conditions of attachment of the rods ends. For example, for longitudinal oscillations of a free rod,
where G is the shear modulus. In the case of flexural oscillations, the natural frequencies do not form a harmonic series, since the rate of propagation of flexural waves is dependent on frequency. For a rod secured at both ends,
where I is the moment of inertia of the cross section with respect to a neutral axis of the rod and the coefficient n assumes the values 1 = 4.73, 2 = 7.85,. . . The form of the free oscillations of the rod depends on which of the free oscillations are found in the spectrum; this, in turn, is determined by the method of excitation.
Under the action of a sinusoidal driving force the rod oscillates at the frequency of the force f (forced oscillations). When the frequency of the force coincides with one of the rods natural frequencies, the phenomenon of resonance occurs.
The practical importance of oscillations of a rod is varied. Any beam in a structural design may be considered as a rod on whose natural frequencies the strength of the structure depends. Dangerous oscillations arising along a ships length because of an engine imbalance may be considered as oscillations of a rod. Rods are used in some musical instruments, such as xylophones. A tuning fork is a curved rod with two free ends.
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The Aggeneys copper-lead-zinc-silver deposits occur in the Precambrian metavolcanic metasedimentary Bushmanland Group which forms part of the Namaqualand Metamorphic Complex. The Bushmanland Basin occupies an area measuring around 18,000km in the western half of the Namaqualand-Natal Mobile Belt.Ore at the Black Mountain Mine is more copper-rich, in contrast to the other deposits to the east which are all more zinc-rich. This deposit comprises two superposed massive sulphide bodies namely the thicker Upper Ore Body (UOB) and a thinner Lower Ore Body (LOB). Both ore bodies, which also carry disseminated sulphides, are hosted in the banded iron formation. The iron formation horizons are both separated by and enveloped in northwest-dipping schist, which is overlain by a thick quartzite formation. The UOB is comprised of three types of iron formation: magnetite quartzite, magnetite- amphibolite and barite-magnetite. Garnet-quartzite forms a halo around the UOB; it is locally enriched in copper (up to 3% copper (Cu)).The LOB consists of baritic to quartzitic schist with disseminated sulphides which grades into magnetiteamphibolite. The footwall to the massive sulphide lenses is characterized by abundant sillimanite.The dip is to the north at 55 (fifty-five degrees) near surface and varies from almost sub horizontal to 40 in the lower western portion of the ore bodies. The contacts of the massive sulphide ore with the host rock are sharp. The ore bodies extend over a strike length of 1,600m from a surface outcrop in the west to about 800m in the east. The stratigraphy consists primarily of footwall schists, which contain little or no water. An unconsolidated weak zone 3m thick, consisting of graphite and mica rich ground, occurs in the footwall. The ore bodies and the hanging wall quartzite's contain water which is associated with fissures and cracks.On a regional scale the area has been subjected to several phases of faulting and folding which has resulted in fracture zones. The surface rocks are invariably jointed and in some areas open partings are present along the east-west striking bedding planes. Much of the jointing and fracturing however extends to depths of less than 200m below surface and it appears that deep open fracturing of geohydrological significance only occurs on quartzite gneiss contacts where late stage folding and fracturing has occurred. The fractured contact zones may act as preferential flow paths for ground water. Black Mountain contains significant lead and copper mineralisation with zinc and silver, while Broken Hill, which is presently being mined, contains the highest grades of lead, zinc and silver, with lesser, although still economically important, copper.Four major sediment-hosted lead-zinc-copper-silver deposits: Broken Hill, Swartberg, Big Syncline and Gamsberg, occur in the Aggeneys area.The Deep ore body's western extremity is approximately 390 m east of, and 240 m below, the current deepest level of the mine (800 m below surface). It has a known down plunge extent of 1 100 m and is open at depth. The deepest position of the ore body is 1 680 m below surface. The Deep ore body is sub-divided into five geologically distinct zones each comprising of iron formation and massive sulphide. Lead-zinc copper-silver mineralisation occurs as fine to coarse disseminations or interbanded in the iron formations. Mineralisation in the massive sulphide is fine-grained and often brecciated. Economic ore occurs in all of the five ore body zones and is predominantly situated at or close to the footwall of each zone. The Deep ore body is contained in a synformal structure with a steep (63-70) and extensive southern limb. The dip is to the north at 55 (fifty-five degrees) near surface and varies from almost sub horizontal to 40 in the lower western portion of the ore bodies. The contacts of the massive sulphide ore with the host rock are sharp. The ore bodies extend over a strike length of 1,600m from a surface outcrop in the west to about 800m in the east. The stratigraphy consists primarily of footwall schists, which contain little or no water. An unconsolidated weak zone 3m thick, consisting of graphite and mica rich ground, occurs in the footwall. The ore bodies and the hanging wall quartzite's contain water which is associated with fissures and cracks.
Production is generated from the Deeps and Swartberg mines. The Deeps mine is serviced by a vertical shaft and Swartberg is accessed through a decline. Total production rate is around 1.7Mtpa, 1.22Mtpa from Deeps and around 0.5Mtpa from Swartberg. This rate is expected to be maintained up to the end of the anticipated mine life in 2023.The main method used is cut-and-fill but where the orebody permits, more massive mining methods such as blasthole and longhole stoping are used to mine stopes of 20m to 30m in height. All production stopes in the Deeps mine are backfilled.
CrushingThe blasted material is taken for crushing. A crushing section is where the ore is crushed by primary, secondary and tertiary crushers to a final product size of 12mm with an 80% passing. Dust generated in this section is suppressed by a dust suppression system to clean the dust-laden air prior to it being discharged to atmosphere.MillingFollowing the crushing section there is a wet grinding section consisting of a rod mill and ball mill, which does not produce dust, where the crushed ore is further reduced in size to facilitate flotation of the various minerals. The rod mill discharge is fed to the first stage cyclones (6 cyclones 4 in use, 2 stand-by), the overflow is gravity fed to the aeration circuit and the underflow goes into the second stage cyclone feed sump. The slurry is pumped from the sump to the second stage cyclones (10 cyclones 6 in use, 4 stand-by) where the overflow is also gravity fed to the aeration circuit and the underflow goes to the ball mill where it is being liberated further. The ball mill discharge combines with the rod mill discharge in the 1 stage cyclone feed sump.
The mill has a nominal capacity of 1.65Mtpa. Ore is sourced primarily from the Broken Hill Deeps orebody and supplemented by feed from Swartberg orebody.Ore is processed using conventional techniques and differential flotation. Ore is passed to the primary crusher and crushed to 150mm. This is passed to the secondary and tertiary crushers and ground to 16mm. After milling the ore is fed into the flotation circuit. Following differential flotation zinc, lead and copper concentrates are produced.The ore contains approximately 35g/t silver, which is recovered in both the copper and lead concentrates.AerationThe cyclone overflow feeds the aeration circuit. From the aeration cells it is pumped to the first conditioner tank of the copper flotation circuit. As the pump passes down the aeration banks, copper is increasingly activated, while lead is progressively depressed. The aeration process is done to ensure that the redox potential is at the correc ........