Xinhai devotes to providing Turn-key Solutions for Mineral Processing Plant (EPC+M+O), namely design and research - complete equipment manufacturing and procurement - commissioning and delivery - mine management - mine operation. The essence of EPC+M+O Service is to ensure sound work in every link. The model is suitable for most of the mines in the world.
Focusing on the research and development and innovation of mineral processing equipment, Xinhai has won more than 100 national patents, strives for perfection, strives to complete the combination of equipment and technology, improve productivity, reduce energy consumption, extend equipment stable operation time, and provide cost-effective services.
With Class B design qualifications in the metallurgical industry, rich in ore mining, beneficiation, smelting technology and experience, completed more than 2,000 mine design and research, not only can provide customers with a reasonable process, but also can provide customized equipment configuration.
The precious metal minerals are mainly gold and silver mines. Xinhai Mining has more than 20 years of experience in beneficiation for gold and silver mines, especially gold ore beneficiation technology. Gold craft and placer gold selection craft etc.
With Class B design qualification, it can provide accurate tests for more than 70 kinds of minerals and design a reasonable beneficiation process. In addition, it can also provide customized complete set of mineral processing equipment and auxiliary parts.
Xinhai can provide the all-round and one-stop mineral processing plant service for clients, solving all the mine construction, operation, management problems, devoting to provide modern, high-efficiency.
Through mineral processing experiment, the mineral processing flow is customized. Multiple tests are carried out in every link, and make sure the final processing flow to guarantee the successful mineral processing plant construction.
According to tailing processing technology, Xinhai has tailings reprocessing technology and tailings dry stacking. Tailings dry stacking is the self-launched tailings dewatering technology, which is the effective technology in green mine construction.
More than 2,000 mine design and research, equipment supply projects, more than 500 mining industry chain services (EPC+M+O) projects in more than 90 countries and regions around the world, we are always committed to providing you with one-stop, customized Chemical mine solution!
A gold processing plant in Song County, Henan Province adoptsflotation + cyanide leaching + carbon slurry adsorption process. The final product is gold-loaded carbon, and cyanide tailings are directly discharged after pressure filtration. In actual production, the concentrating plant often has the phenomenon of process interruption and operation stoppage due to equipment failure, which greatly reduces the equipment operation rate and seriously affects the smoothness and continuity of the process.In addition, thisgold processing plant has been in operation for a long time, the grade of feeding ore selected by the processing plant is decreasing year by year, and the ore is depleted seriously, the recovery rate of ore dressing is also reduced. Therefore, the process method has been modified to improve the equipment operation rate and the ore recovery rate, thereby improving the economic benefits of the enterprise.
The type of ore in a gold mine is altered coarse-faced rock. The main types of alteration are pyrolysis,silicification, pyrite mineralization, chlorite petrochemical, localsilicificationis strong, and quartz veins are visible. The ore is all native ore. The ore process type is a smallsulphidegold ore, and the metal mineral is mainly pyrite.
Ore structure:anhedralform grain structure, inclusion structure, self-half self-shaped grain structure,polygranularstructure, plaque structure, rough surface structure and so on. Most of the pyrite and natural gold, chalcopyrite, sphalerite, and galena are crystallized in the ore to formaanhedralform grain structure.
The gold grade in the ore is 1.56g/t, mainly fine particles, and little micro-particles. Most of which are concentrated in the range of 0.037-0.01mm. Natural gold is mainly embedded in pyrite, mainly inclusion gold (89.64%), followed by cracked gold (10.36%).
The raw ore from the primary binfirstlyenters the C80 type jaw crusher for coarse crushing, and then enters the JP158 cone crusher for medium crushing. After the medium crushing, it enters the 10mm*10mm vibrating screen. The ore larger than 10mm returns to the JP108 cone crusher for fine crushing. Ore less than 10mm directly enters the powder ore bin.
The ore directly enters the GQC2700*3600 grateball mill (grinding medium is 100mm cast steel ball) from the powder ore mine, and then enters the single spiral classifier. The coarse particles in the slurry become grit, and the fine particles are discharged from the overflow port. The finer particles passing through the classifier overflow into thehydrocyclonefor re-classification. The overflow flows directly into the flotation process through the high-efficiency agitation tank, and the grit returnsto the ball mill for re-grinding, thus forming a closed loop.
The flotation process is a closed circuit including once roughselection,three times fine selections, and twice sweep selections. The supplements are butyl xanthate and black no. 25, and the foaming agent is No. 2 oil. The flotation concentrate enters the thickener for concentration, and the flotation tailings are pumped into the tailings pond through a ball isolation pump.
The flotation concentrate is re-grinded by 3 mixing mills (grinding medium is 10mm steel balls), so that the fineness of the ore particles reaches -0.037mm, accounting for more than 90%, and then the slurry concentration is controlled to 37% by the mixing tank. 40%, and finally enter the charcoal dipping tank for leaching and adsorption to obtain gold-loaded charcoal.
In actual production, improving equipment integrity and operation rate, maintaining production and process continuity and stability, can create favorable conditions for improving various technical indicators of mineral processing. In the process of mineral processing, promoting energy conservation and consumption reduction can effectively reduce energy costs and improve economic efficiency. As current production costs increase, metal loss should be reduced as much as possible. Therefore, reducing production costs and increasing the recovery rate of the processing planthasbecome important issues for it.
There are 2 ball isolation pumps in the processingplant, which correspond to 2 multi-stage centrifugal pumps, which can be used for 1 operation and 1 preparation. The multistage centrifugal water pump is connected to the ball isolation pump as shown in Figure 1.
1 - Multi-stage centrifugal water pump 2 - Transformer 3 - Controller 4 - Buffer tank 5 - Hydraulic station 6 - Inlet clean water valve 7 - Back clean water valve 8 - Isolation tank 9 - Slurry outlet check valve 10 - Slurry inlet check valve
In actual production, each device may malfunction at any time. This may cause No. 1 pumpfailor No. 1 ball isolation pump fail. ThenNo. 2 pump and the No. 2 ball isolation pumpmust be used, ifNo. 2 pump or No. 2 ball isolation pump also failed, which inevitably caused the entire concentrating plant to be interrupted. In order to avoid such problems, the connection method between the pump and the ball isolation pump shall be improved: crosslink the inlet pipe of the No. 2 isolation pump, that is, the outlet pipe of the No. 2 pump, is cross-connected, which makes the No. 1 pump and 2 The ball isolation pump is connected, and the peer pump also connects the No. 2 pump to the No. 1 ball isolation pump, so that each pump or each ball isolation pump corresponds to the No. 2 ball isolation pump or the No. 2 pump. Therefore, when the No. 1 pump fails, it is only necessary to use the No. 2 pump, and it is not necessary to use the ball to isolate the pump. Other cases as well.
The re-grinding operation of the processing plantis carried out by three agitating mills. Although the fineness of grinding can meet the production requirements, from the perspective of energy saving and consumption reduction, the motor power of the agitating mill is 75kW, the power consumption is large, and the equipment is too old, and the work is not continuous. Therefore, it is replaced with a tower mill (motor power is 50kW), which not only can achieve continuous operation, but also consumes less than 1/3 of the agitatingmill, which can greatly reduce the cost. The structure of the tower mill is shown in Figure 2.
The grinding fineness of the regrind operation can ensure good leaching effect at present, but in order to further improve the gold recovery rate, the barrenliquid(mass concentration about 0.01 g/m3) after the activated carbon is adsorbed to the activated carbon is again sent to the activated carbon adsorption tower for further re-extraction. The adsorption (mass concentration after adsorption is 0.004 g/m3) can further increase the recovery rate by about 0.02%.
In the cyanidation tailing, due to the high gradeof lead and other metals, the direct discharge afterpress filteringleads to the loss of metal. In the subsequent process, add a cyclone-static micro-bubble flotation column (see Figure 3). The slag is pumped into the flotation column for flotation, which can effectively recover metals such as lead.
Different conditions were tested on the new cyclone-static micro-bubble flotation column, and the flotation condition of the flotation column was discussed. The total mass fraction of the preparation was 20%. The test results are shown in Table 1.
Under different experimental conditions, through the comparison and comprehensive analysis of the recovery rates of gold, silver and lead metals, it can be seen that when the concentrationdensityis about 37%, the dosage of butyl (butyl ketone + butyl ammonium black medicine) is 30mL, higher recovery rate can be obtained.
The processing capacity of the processing plantis 900t/d, and the output rate of cyanide tailing is about 3.8%, that is, the daily output of cyanide tailing is about 34.2t. The cyanide tailing gold grade is about 3.1g/t, the silver grade is about 34g/t, and the lead grade is about 3.5g/t. It can be estimated that the annual recovery of gold is 16.58kg, silver 48.19kg and lead 23.14kg. It can be seen that by increasing the flotation column, the re-recycling of gold, silver and lead can achieve certain economic benefits.
In the actual production of the processing plant, failureof any one equipmentmay lead to interruption of the production process, so the high operating rate of the equipment is the guarantee of the stability and continuity of the production process. With the reduction of feeding ore grade and energy conservation and consumption reduction, it is urgent to reduce production costs and increase the recovery rate of ore dressing.
4.1 The modification of the ball isolation pump changed the previous "1 to 1" to "1 to 2", which avoidsor reducesthe stoppage of the production operation of the processing plantand improvesthe operation rate of the equipment.
4.3 The gold recovery rate can be improved by re-injecting the hydrogen-depleted lean liquid into the carbon adsorption column. The use of flotation column to re-recycle the metal in the cyanide tailing can greatly improve the processrecovery rate, reduce metal loss, and obtain certain economic benefits.
With dozens of mineral processing experts in the field of gold, copper, lead-zinc, silver, coal and etc.,HOT Miningcan provide services for new mineral processing plant engineeringdesign(feasibility study, preliminary design, detail design and construction design) and existing mineral processing plant modification and upgrade. Especially we have rich experience in goldCIP,CIL, CICandflotation.
Xinhai grinding mill has excellent energy saving ability. According to the customer demand, manganese steel liner and wear-resistant rubber liner can be customized for Xinhai ball mill with good wear resistance, long service life, easy maintenance
High-quality equipment manufacturing capabilities, focusing on the research and development and innovation of mineral processing equipment, extending the stable operation time of the equipment, and providing cost-effective services.
Placer mining and lode mining are very different. Whereas placer gold has been released from within the rock and is generally free from any significant matrix, lode gold presents different challenges. While gold may be present in ore, it must somehow be released for proper extraction.
As a result, a number of machines have been invented to bring about maximum results with regard to obtaining the much needed resource, gold. One of such equipment is the ball mill. Below is the write-up of how a ball mill works, is used to crush ore and an explanation regarding its effectiveness in gold mining.
First of all, in order to get the best out of how this particular equipment is used it is important to get acquainted with knowledge on what it is, and is made of. Hence, a mill is a piece of equipment used to grind ores. Its major purpose is to perform the grinding and blending of rocks and ores to release any free-gold that is contained within them.
At major mines, the mill was the critical equipment that was required to process the ores that were extracted from deep underground. Many early mines used stamp mills, but many operations today find that ball mills are more functional for smaller operations and perform well with the modern equipment we have available now such as combustion engines.
To perform its functions, the ball mill operates on the principle of impact and attrition. This principle entails that the balls are dropped from near the top of the shell in order to bring about size reduction impact.
The major components of the ball mill include a shell that is hollow and is suspended on its axis to bring about rotation. The axis of the shell can be suspended horizontally or at an angle to the horizontal.
The shell is filled with quite few, but reasonable amount of balls which do the grinding process, and can be made of steel such as chrome steel and stainless steel. They can also be made of ceramic or rubber depending on their targeted material to be ground.
Its major operations are categorized into two, namely the dry and wet processes. Through those processes the machine is able to perform its functions of grinding the crushed materials. One of such functions, is that which is witnessed when grinding different types of ore, such as gold ore.
Now here is what one must know with regard to how the ball mill operates. The drum of the mill (shell) is suspended on two self-aligned rollers. Then the material to be worked on is loaded through the hopper.
From there, the mill is driven using a motor with a clutch, gearbox and the flexible coupling. The mill is then lifted to a certain level of height as it rotates. It is from that height that the balls begin to freely fall or roll down in order to grind the material that has been loaded.
After the material is ground, it is then removed from the mill depending on the discharge method used on the machine. For example, there are center unloading mills as well as unloading through the grille mills.
For the center unloading mills, the ground material is discharged through a hollow unloading trunnion using a free sink. To make it more efficient the pulp level in the drum should at least be above the level of the lower generating trunnion for unloading.
On the other hand, mills whose unloading is done using the grid consist of a lifting device which helps to unload the crushed material. For this reason, in such a mill the slurry level is likely to be lower compared to the unlading trunnion level. In such a mill, a grid with openings used for unloading crushed material is located in the unloading end of the drum.
To crush the gold ore in order to obtain pure gold, the large ore of gold is fed into a jaw crusher or mobile jaw crusher for the primary crushing process. The crushing process acts as a medium of screening the fine gold ore. It is then sieved using the vibrating screen and later sent through the use of a conveyer belt.
The ore is sent into a single-cylinder hydraulic cone crusher for the secondary crushing. Thereafter, the gold ore is transferred to a multi-cylinder hydraulic cone crusher, where the ore is crushed further into finer material. From there, the crushed gold ore is sent to a ball mill, evenly as it passes through a vibrating screen for grinding.
From the ball mill, the gold ore powder is subjected to the process known as beneficiation for further crushing before classification and floatation processes. Most commonly, professional mining operations will use a shaker table at this point. These are extremely effective at capturing tiny particles of free-gold that has been released from the ores.
We sent a substantial amount ofquartz gold ore to a mill for processing. After a couple hundred tests on the material an average grade wascalculated. After milling for several days the mill says there is way less gold in the ore than what had been estimated.
Once milling began samples were taken once per shift, ball mill discharge, cyclone overflow, concentrate, and tails. Samples were sent to a lab for assay. With these samples the Lab has determined that there is at least 1 gpt missing that did not report to the concentrate or the tails. Theory from the lab is gold is stuck in the grinding circuit.
They are using flotation, metallurgy testing showed a decent recovery with gravity but a better recovery with flotation. Although in reality recovery was horrible below 60% This is mainly free gold, although it is very fine gold, as small as 10 micron size and the largest pieces being in the neighborhood of 500 micron. Also the ore has very little sulfides
If the cyclone underflow gold grade was higher than the cyclone overflow grade then you have free gold and you should look at putting a centrifugal concentrator in the grinding circuit. For low tonnage operations you can feed 100% of the ball mill discharge to the concentrator (this requires an extra pump, but is worth the effort). Modern units can recover free gold down to the 10 micron size range or finer.
In regards to the met balance, normal practice is to take the tails grade, feed tons, and gold produced and back calculate the head grade. Sampling the feed for head grade is always difficult. As a side comment, I'm not sure how your assay would be any more accurate than what is calculated in the met balance, but that is always the case to be argued between the miner and the mill guy. You can also compare the mill feed grade to the cyclone overflow grade to see if there are any losses in the grinding circuit.
You also need to check all the gold traps in the grinding circuit, i.e. cyclone feed pump box, cyclone underflow launders etc. They should be clean when you start your run, and cleaned out after you finish the run, including a full grind-out of the mill.
Free gold can also accumulate in the mill, either in the liners (at the Echo Bay Lupin operation when they took out the steel liners during a liner change they would put them in a secure area and grind off the surface to recover a lot of gold), or behind the liners (just ask any mill mechanic that does liner changes).
Thank you Andrew this is helpful, big problem with this material is the nugget affect when it comes to sampling. I was allowed to take 1 set of samples when I visited the mill, I took cyclone overflow and underflow, the difference was about 1.8 -1 and this is not a surprise as we know there is free gold.
This is a custom mill, I don't want to get to much into details as I don't want to smear anyone's name just yet. I'm just trying to understand whats happening and what can happen as for my one question to do with the head grade being way lower than expected grades.
Absolutely you can loose gold in the mill grinding circuit, in the classifier, in the bottom of the sand pump, behind the liners etc. particularly steel liners. When starting a new mill it will take some time before you can come up with a proper metallurgical balance, every crook and cranny, needs to to be filled before you can come up with what is in the head shows up in either the concentrate or the tailings. I have taken 40 ounces out of a small, 4' x 4' mill when I removed the liners, and any time you tear down a gold mill you have a pretty good pay day from trapped gold. Also since I am somewhat pessimistic, be sure there are no hidden traps, there on purpose, for the mill owner to make a little extra money, I have run into this, gold doe's funny things to people. My experience with custom mills is that you will likely never agree, best thing to do is come up with a good sampling system where you both can agree on a assay, sample for you, one for them, one for an umpire assay and then sell them the ore. Once you sell the ore to them you don't care what they do with it even if they want to make road gravel out of it.
Gold settling in tanks, gold room sumps or locked up in roasters This can be difficult to detect unless one goes looking for it or there is a policy of regular clean up. Similar problems occur in hydrometallurgical plants.
You may want to hire an experienced extractive metallurgist to give you a hand. This is the kind of thing I have done for over 50 years and helped many people with this kind of problems, it would likely be well worth the money.
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For thousands of years the word gold has connoted something of beauty or value. These images are derived from two properties of gold, its colour and its chemical stability. The colour of gold is due to the electronic structure of the gold atom, which absorbs electromagnetic radiation with wavelengths less than 5600 angstroms but reflects wavelengths greater than 5600 angstromsthe wavelength of yellow light. Golds chemical stability is based on the relative instability of the compounds that it forms with oxygen and watera characteristic that allows gold to be refined from less noble metals by oxidizing the other metals and then separating them from the molten gold as a dross. However, gold is readily dissolved in a number of solvents, including oxidizing solutions of hydrochloric acid and dilute solutions of sodium cyanide. Gold readily dissolves in these solvents because of the formation of complex ions that are very stable.
Gold (Au) melts at a temperature of 1,064 C (1,947 F). Its relatively high density (19.3 grams per cubic centimetre) has made it amenable to recovery by placer mining and gravity concentration techniques. With a face-centred cubic crystal structure, it is characterized by a softness or malleability that lends itself to being shaped into intricate structures without sophisticated metalworking equipment. This in turn has led to its application, from earliest times, to the fabrication of jewelry and decorative items.
The history of gold extends back at least 6,000 years, the earliest identifiable, realistically dated finds having been made in Egypt and Mesopotamia c. 4000 bc. The earliest major find was located on the Bulgarian shores of the Black Sea near the present city of Varna. By 3000 bc gold rings were used as a method of payment. Until the time of Christ, Egypt remained the centre of gold production. Gold was, however, also found in India, Ireland, Gaul, and the Iberian Peninsula. With the exception of coinage, virtually all uses of the metal were decorativee.g., for weapons, goblets, jewelry, and statuary.
Egyptian wall reliefs from 2300 bc show gold in various stages of refining and mechanical working. During these ancient times, gold was mined from alluvial placersthat is, particles of elemental gold found in river sands. The gold was concentrated by washing away the lighter river sands with water, leaving behind the dense gold particles, which could then be further concentrated by melting. By 2000 bc the process of purifying gold-silver alloys with salt to remove the silver was developed. The mining of alluvial deposits and, later, lode or vein deposits required crushing prior to gold extraction, and this consumed immense amounts of manpower. By ad 100, up to 40,000 slaves were employed in gold mining in Spain. The advent of Christianity somewhat tempered the demand for gold until about the 10th century. The technique of amalgamation, alloying with mercury to improve the recovery of gold, was discovered at about this time.
The colonization of South and Central America that began during the 16th century resulted in the mining and refining of gold in the New World before its transferal to Europe; however, the American mines were a greater source of silver than gold. During the early to mid-18th century, large gold deposits were discovered in Brazil and on the eastern slopes of the Ural Mountains in Russia. Major alluvial deposits were found in Siberia in 1840, and gold was discovered in California in 1848. The largest gold find in history is in the Witwatersrand of South Africa. Discovered in 1886, it produced 25 percent of the worlds gold by 1899 and 40 percent by 1985. The discovery of the Witwatersrand deposit coincided with the discovery of the cyanidation process, which made it possible to recover gold values that had escaped both gravity concentration and amalgamation. With E.B. Millers process of refining impure gold with chlorine gas (patented in Britain in 1867) and Emil Wohlwills electrorefining process (introduced in Hamburg, Ger., in 1878), it became possible routinely to achieve higher purities than had been allowed by fire refining.
The major ores of gold contain gold in its native form and are both exogenetic (formed at the Earths surface) and endogenetic (formed within the Earth). The best-known of the exogenetic ores is alluvial gold. Alluvial gold refers to gold found in riverbeds, streambeds, and floodplains. It is invariably elemental gold and usually made up of very fine particles. Alluvial gold deposits are formed through the weathering actions of wind, rain, and temperature change on rocks containing gold. They were the type most commonly mined in antiquity. Exogenetic gold can also exist as oxidized ore bodies that have formed under a process called secondary enrichment, in which other metallic elements and sulfides are gradually leached away, leaving behind gold and insoluble oxide minerals as surface deposits.
Endogenetic gold ores include vein and lode deposits of elemental gold in quartzite or mixtures of quartzite and various iron sulfide minerals, particularly pyrite (FeS2) and pyrrhotite (Fe1-xS). When present in sulfide ore bodies, the gold, although still elemental in form, is so finely disseminated that concentration by methods such as those applied to alluvial gold is impossible.
Native gold is the most common mineral of gold, accounting for about 80 percent of the metal in the Earths crust. It occasionally is found as nuggets as large as 12 millimetres (0.5 inch) in diameter, and on rare occasions nuggets of native gold weighing up to 50 kilograms are foundthe largest having weighed 92 kilograms. Native gold invariably contains about 0.1 to 4 percent silver. Electrum is a gold-silver alloy containing 20 to 45 percent silver. It varies from pale yellow to silver white in colour and is usually associated with silver sulfide mineral deposits.
Gold also forms minerals with the element tellurium; the most common of these are calaverite (AuTe2) and sylvanite (AuAgTe4). Other minerals of gold are sufficiently rare as to have little economic significance.
Of the worlds known mineral reserves of gold ore, 50 percent is found in South Africa, and most of the rest is divided among Russia, Canada, Australia, Brazil, and the United States. The largest single gold ore body in the world is in the Witwatersrand of South Africa.
Gold and copper mineralization at Telfer consists of stratiform reefs and stockworks hosted by sedimentary rocks of the Malu Formation of the Lamil Group. The Lamil Group comprises relatively weakly deformed and metamorphosed Proterozoic sediment units northeast of the Camel-Tabletop Fault. The important attributes of the Lamil Group are the presence of abundant carbonate units, and weakly developed penetrative deformation.The topography at the Telfer mine site is dominated by two large scale asymmetric dome structures with steep west dipping axial planes. Main Dome is located in the southeast portion of the mine and is exposed over a strike distance of 3km north-south and 2km east-west before plunging under transported cover. West Dome forms the topographical high in the northwest quadrant of the mine and has similar dimensions to Main Dome. Both fold structures have shallow to moderately dipping western limbs and moderate to steep dipping eastern limbs. Mineral Resources reported for the Telfer mining centre consist of: open pit stockwork and reef mineralization in Telfer Main Dome and West Dome; stockwork and reef mineralization mined underground in the Telfer Underground SLC mining operation; stockwork mineralization in the VSC below the SLC.Mineralization within the Telfer deposit is controlled by structure and lithology. Several styles of mineralization were recognized, namely narrow high-grade reefs, pod-like mineralized bodies, sheeted vein-sets and large areas of low grade stockwork mineralization, with the latter forming the majority of the sulphide resource. The primary mineralization was overprinted by surface weathering processes.The sulphide mineralization is characterized by fresh sulphides, predominantly pyrite and chalcopyrite. The main copper minerals listed in order of occurrence are chalcopyrite, chalcocite and bornite with minor cobaltite and nickel-sulphide. Primary gold generally occurs as free grains, on sulphide boundaries and to a minor degree with silica grains. Primary gold mineralization is typically associated with pyrite/chalcopyrite sulphides and quartz/dolomite gangue. There is a correlation between vein frequency and gold grade.Weathering locally modified the mineralization, to depths typically up to 200m, with the boundary between oxide and primary mineralization being irregular. The weathering profile produced local areas of supergene enrichment where the copper to sulphur ratio is characteristically higher. Supergene minerals include gold with limonite/goethite, malachite and chrysocolla in the depleted oxide zone, giving way to chalcocite, pyrite, digenite, covellite, tenorite and cuprite at depth in primary mineralization. The copper to sulphur ratio decreases with depth below the supergene zones. Copper is, in general, more mobile in these supergene area zones than gold. The depth of oxidation is closely related to the structural framework and typically exists to approximately 200m below surface, although local areas show oxidation down faults in excess of 500m below surface.The highest concentration of gold and copper grades occurs within bedding sub-parallel reef systems. In Main Dome a total of 21 reef structures were identified from drill hole data or mapping of surface and underground exposures within the Open Pit Mineral Resource, and include 10 E-Reefs within the Outer Siltstones, the MVR within the Middle Vale Siltstone and the M10 to M50 series of reefs within the Malu Formation. The primary characteristics of the reef systems are: broadly concordant to lithological boundaries; laterally extensive (greater than 1km) both along strike and dip; true thickness of 0.1m to 1.2m, averaging between 0.3m and 0.7m; high relative nugget effect; variable dip varying from flat at the crest of Main Dome to about 40 on the eastern flank of Main Dome; gold grade is typically high but variable: 5 g/t Au to 50 g/t Au; copper grade ranges between 0.2% Cu and 1.5% Cu.Stockwork mineralization is characterized by narrow, often discontinuous veins that crosscut stratigraphy. Large domains of stockwork mineralization were defined in the open pits and also within the Telfer Deeps and Vertical Stockwork Corridor Mineral Resources. Stockwork mineralization is best developed in the axial zones of Main Dome and West Dome and is discordant to lithological boundaries, although some stratigraphic units have more abundant stockworks than others and vein intensity within stockwork can be greater adjacent to reefs. Stockworks are laterally extensive, between 0.1km to 1.5km scale and the geometry of the stockwork zones is related to structure and stratigraphy.Stockwork mineralization can also include areas of breccia dominated by quartz, carbonate and sulphides.
The Telfer operation is comprised of open pit mining at both Main Dome and West Dome and underground mining at Main Dome. Open pit mining is a conventional truck and hydraulic excavator operation. Underground selective and bulk long hole open stope mining methods are used for excavation of the high-grade reefs and Western Flanks respectively, while stockwork ore and waste are mined using sub level cave bulk mining methods. Underground sub level cave mining ore and Western Flanks bulk open stope ore is hoisted to the surface via a shaft.Open pit mining has continued at both Main Dome and West Dome open pits (including stockpile reclaim). Since 31 December 2019, the Mineral Resources and Ore Reserves were depleted by 0.2 million ounces of gold and 0.01 million tonnes of copper. Mining of Ore Reserves in the Main Dome open pit was completed in the fourth quarter of FY20. Further studies are currently evaluating potential for additional Ore Reserves in Main Dome open pit.The Telfer Underground comprises the sub level cave mine and selective high-grade reef mining and Western Flanks reef and stockwork mining. Since 31 December 2019, both the Mineral Resources and Ore Reserves have been depleted by 0.05 million ounces of gold and <0.01 million tonnes of copper. Underground Ore Reserves for the sub level cave were completed. Further studies are currently evaluating the potential for additional Ore Reserves at the sub level cave and other underground areas to extend the underground mine life.
The Telfer concentrator comprises a dual train comminution circuit followed by flotation and a carbon-in-leach (CIL) circuit. The two processing trains contain two stage grinding circuits each comprising a 15 MW SAG mill and 13 MW ball mill.
The Telfer concentrator comprises a dual train comminution circuit followed by flotation and a carbon-in-leach (CIL) circuit. Both streams contain a gravity gold recovery circuit. Approximately 40% of the gold at Telfer is produced as dor which is smelted on site. Following the gravity recovery circuit ore with: gravity recovery circuit ore with:-A relatively low pyrite content is treated in a conventional single stage flotation circuit to produce gold copper concentrate;-A higher pyrite content is treated via a sequential flotation process. The first stage is a conventional copper flotation with depression of pyrite to produce a gold-copper concentrate. Tails from the first stage are refloated to produce a pyrite-gold concentrate which is leached with cyanide in a conventional CIL circuit to recover the remaining gold as dor.The gold-copper concentrate is trucked to Port Hedland for shipping to smelters, primarily in the East Asia region.
In all ore dressing and milling Operations, including flotation, cyanidation, gravity concentration, and amalgamation, the Working Principle is to crush and grind, often with rob mill & ball mills, the ore in order to liberate the minerals. In the chemical and process industries, grinding is an important step in preparing raw materials for subsequent treatment.In present day practice, ore is reduced to a size many times finer than can be obtained with crushers. Over a period of many years various fine grinding machines have been developed and used, but the ball mill has become standard due to its simplicity and low operating cost.
A ball millefficiently operated performs a wide variety of services. In small milling plants, where simplicity is most essential, it is not economical to use more than single stage crushing, because the Steel-Head Ball or Rod Mill will take up to 2 feed and grind it to the desired fineness. In larger plants where several stages of coarse and fine crushing are used, it is customary to crush from 1/2 to as fine as 8 mesh.
Many grinding circuits necessitate regrinding of concentrates or middling products to extremely fine sizes to liberate the closely associated minerals from each other. In these cases, the feed to the ball mill may be from 10 to 100 mesh or even finer.
Where the finished product does not have to be uniform, a ball mill may be operated in open circuit, but where the finished product must be uniform it is essential that the grinding mill be used in closed circuit with a screen, if a coarse product is desired, and with a classifier if a fine product is required. In most cases it is desirable to operate the grinding mill in closed circuit with a screen or classifier as higher efficiency and capacity are obtained. Often a mill using steel rods as the grinding medium is recommended, where the product must have the minimum amount of fines (rods give a more nearly uniform product).
Often a problem requires some study to determine the economic fineness to which a product can or should be ground. In this case the 911Equipment Company offers its complete testing service so that accurate grinding mill size may be determined.
Until recently many operators have believed that one particular type of grinding mill had greater efficiency and resulting capacity than some other type. However, it is now commonly agreed and accepted that the work done by any ballmill depends directly upon the power input; the maximum power input into any ball or rod mill depends upon weight of grinding charge, mill speed, and liner design.
The apparent difference in capacities between grinding mills (listed as being the same size) is due to the fact that there is no uniform method of designating the size of a mill, for example: a 5 x 5 Ball Mill has a working diameter of 5 inside the liners and has 20 per cent more capacity than all other ball mills designated as 5 x 5 where the shell is 5 inside diameter and the working diameter is only 48 with the liners in place.
Ball-Rod Mills, based on 4 liners and capacity varying as 2.6 power of mill diameter, on the 5 size give 20 per cent increased capacity; on the 4 size, 25 per cent; and on the 3 size, 28 per cent. This fact should be carefully kept in mind when determining the capacity of a Steel- Head Ball-Rod Mill, as this unit can carry a greater ball or rod charge and has potentially higher capacity in a given size when the full ball or rod charge is carried.
A mill shorter in length may be used if the grinding problem indicates a definite power input. This allows the alternative of greater capacity at a later date or a considerable saving in first cost with a shorter mill, if reserve capacity is not desired. The capacities of Ball-Rod Mills are considerably higher than many other types because the diameters are measured inside the liners.
The correct grinding mill depends so much upon the particular ore being treated and the product desired, that a mill must have maximum flexibility in length, type of grinding medium, type of discharge, and speed.With the Ball-Rod Mill it is possible to build this unit in exact accordance with your requirements, as illustrated.
To best serve your needs, the Trunnion can be furnished with small (standard), medium, or large diameter opening for each type of discharge. The sketch shows diagrammatic arrangements of the four different types of discharge for each size of trunnion opening, and peripheral discharge is described later.
Ball-Rod Mills of the grate discharge type are made by adding the improved type of grates to a standard Ball-Rod Mill. These grates are bolted to the discharge head in much the same manner as the standard headliners.
The grates are of alloy steel and are cast integral with the lifter bars which are essential to the efficient operation of this type of ball or rod mill. These lifter bars have a similar action to a pump:i. e., in lifting the product so as to discharge quickly through the mill trunnion.
These Discharge Grates also incorporate as an integral part, a liner between the lifters and steel head of the ball mill to prevent wear of the mill head. By combining these parts into a single casting, repairs and maintenance are greatly simplified. The center of the grate discharge end of this mill is open to permit adding of balls or for adding water to the mill through the discharge end.
Instead of being constructed of bars cast into a frame, Grates are cast entire and have cored holes which widen toward the outside of the mill similar to the taper in grizzly bars. The grate type discharge is illustrated.
The peripheral discharge type of Ball-Rod Mill is a modification of the grate type, and is recommended where a free gravity discharge is desired. It is particularly applicable when production of too many fine particles is detrimental and a quick pass through the mill is desired, and for dry grinding.
The drawings show the arrangement of the peripheral discharge. The discharge consists of openings in the shell into which bushings with holes of the desired size are inserted. On the outside of the mill, flanges are used to attach a stationary discharge hopper to prevent pulp splash or too much dust.
The mill may be operated either as a peripheral discharge or a combination or peripheral and trunnion discharge unit, depending on the desired operating conditions. If at any time the peripheral discharge is undesirable, plugs inserted into the bushings will convert the mill to a trunnion discharge type mill.
Unless otherwise specified, a hard iron liner is furnished. This liner is made of the best grade white iron and is most serviceable for the smaller size mills where large balls are not used. Hard iron liners have a much lower first cost.
Electric steel, although more expensive than hard iron, has advantage of minimum breakage and allows final wear to thinner section. Steel liners are recommended when the mills are for export or where the source of liner replacement is at a considerable distance.
Molychrome steel has longer wearing qualities and greater strength than hard iron. Breakage is not so apt to occur during shipment, and any size ball can be charged into a mill equipped with molychrome liners.
Manganese liners for Ball-Rod Mills are the world famous AMSCO Brand, and are the best obtainable. The first cost is the highest, but in most cases the cost per ton of ore ground is the lowest. These liners contain 12 to 14% manganese.
The feed and discharge trunnions are provided with cast iron or white iron throat liners. As these parts are not subjected to impact and must only withstand abrasion, alloys are not commonly used but can be supplied.
Gears for Ball-Rod Mills drives are furnished as standard on the discharge end of the mill where they are out of the way of the classifier return, scoop feeder, or original feed. Due to convertible type construction the mills can be furnished with gears on the feed end. Gear drives are available in two alternative combinations, which are:
All pinions are properly bored, key-seated, and pressed onto the steel countershaft, which is oversize and properly keyseated for the pinion and drive pulleys or sheaves. The countershaft operates on high grade, heavy duty, nickel babbitt bearings.
Any type of drive can be furnished for Ball-Rod Mills in accordance with your requirements. Belt drives are available with pulleys either plain or equipped with friction clutch. Various V- Rope combinations can also be supplied.
The most economical drive to use up to 50 H. P., is a high starting torque motor connected to the pinion shaft by means of a flat or V-Rope drive. For larger size motors the wound rotor (slip ring) is recommended due to its low current requirement in starting up the ball mill.
Should you be operating your own power plant or have D. C. current, please specify so that there will be no confusion as to motor characteristics. If switches are to be supplied, exact voltage to be used should be given.
Even though many ores require fine grinding for maximum recovery, most ores liberate a large percentage of the minerals during the first pass through the grinding unit. Thus, if the free minerals can be immediately removed from the ball mill classifier circuit, there is little chance for overgrinding.
This is actually what has happened wherever Mineral Jigs or Unit Flotation Cells have been installed in the ball mill classifier circuit. With the installation of one or both of these machines between the ball mill and classifier, as high as 70 per cent of the free gold and sulphide minerals can be immediately removed, thus reducing grinding costs and improving over-all recovery. The advantage of this method lies in the fact that heavy and usually valuable minerals, which otherwise would be ground finer because of their faster settling in the classifier and consequent return to the grinding mill, are removed from the circuit as soon as freed. This applies particularly to gold and lead ores.
Ball-Rod Mills have heavy rolled steel plate shells which are arc welded inside and outside to the steel heads or to rolled steel flanges, depending upon the type of mill. The double welding not only gives increased structural strength, but eliminates any possibility of leakage.
Where a single or double flanged shell is used, the faces are accurately machined and drilled to template to insure perfect fit and alignment with the holes in the head. These flanges are machined with male and female joints which take the shearing stresses off the bolts.
The Ball-Rod Mill Heads are oversize in section, heavily ribbed and are cast from electric furnace steel which has a strength of approximately four times that of cast iron. The head and trunnion bearings are designed to support a mill with length double its diameter. This extra strength, besides eliminating the possibility of head breakage or other structural failure (either while in transit or while in service), imparts to Ball-Rod Mills a flexibility heretofore lacking in grinding mills. Also, for instance, if you have a 5 x 5 mill, you can add another 5 shell length and thus get double the original capacity; or any length required up to a maximum of 12 total length.
On Type A mills the steel heads are double welded to the rolled steel shell. On type B and other flanged type mills the heads are machined with male and female joints to match the shell flanges, thus taking the shearing stresses from the heavy machine bolts which connect the shell flanges to the heads.
The manhole cover is protected from wear by heavy liners. An extended lip is provided for loosening the door with a crow-bar, and lifting handles are also provided. The manhole door is furnished with suitable gaskets to prevent leakage.
The mill trunnions are carried on heavy babbitt bearings which provide ample surface to insure low bearing pressure. If at any time the normal length is doubled to obtain increased capacity, these large trunnion bearings will easily support the additional load. Trunnion bearings are of the rigid type, as the perfect alignment of the trunnion surface on Ball-Rod Mills eliminates any need for the more expensive self-aligning type of bearing.
The cap on the upper half of the trunnion bearing is provided with a shroud which extends over the drip flange of the trunnion and effectively prevents the entrance of dirt or grit. The bearing has a large space for wool waste and lubricant and this is easily accessible through a large opening which is covered to prevent dirt from getting into the bearing.Ball and socket bearings can be furnished.
Scoop Feeders for Ball-Rod Mills are made in various radius sizes. Standard scoops are made of cast iron and for the 3 size a 13 or 19 feeder is supplied, for the 4 size a 30 or 36, for the 5 a 36 or 42, and for the 6 a 42 or 48 feeder. Welded steel scoop feeders can, however, be supplied in any radius.
The correct size of feeder depends upon the size of the classifier, and the smallest feeder should be used which will permit gravity flow for closed circuit grinding between classifier and the ball or rod mill. All feeders are built with a removable wearing lip which can be easily replaced and are designed to give minimum scoop wear.
A combination drum and scoop feeder can be supplied if necessary. This feeder is made of heavy steel plate and strongly welded. These drum-scoop feeders are available in the same sizes as the cast iron feeders but can be built in any radius. Scoop liners can be furnished.
The trunnions on Ball-Rod Mills are flanged and carefully machined so that scoops are held in place by large machine bolts and not cap screws or stud bolts. The feed trunnion flange is machined with a shoulder for insuring a proper fit for the feed scoop, and the weight of the scoop is carried on this shoulder so that all strain is removed from the bolts which hold the scoop.
High carbon steel rods are recommended, hot rolled, hot sawed or sheared, to a length of 2 less than actual length of mill taken inside the liners. The initial rod charge is generally a mixture ranging from 1.5 to 3 in diameter. During operation, rod make-up is generally the maximum size. The weights per lineal foot of rods of various diameters are approximately: 1.5 to 6 lbs.; 2-10.7 lbs.; 2.5-16.7 lbs.; and 3-24 lbs.
Forged from the best high carbon manganese steel, they are of the finest quality which can be produced and give long, satisfactory service. Data on ball charges for Ball-Rod Mills are listed in Table 5. Further information regarding grinding balls is included in Table 6.
Rod Mills has a very define and narrow discharge product size range. Feeding a Rod Mill finer rocks will greatly impact its tonnage while not significantly affect its discharge product sizes. The 3.5 diameter rod of a mill, can only grind so fine.
Crushers are well understood by most. Rod and Ball Mills not so much however as their size reduction actions are hidden in the tube (mill). As for Rod Mills, the image above best expresses what is going on inside. As rocks is feed into the mill, they are crushed (pinched) by the weight of its 3.5 x 16 rods at one end while the smaller particles migrate towards the discharge end and get slightly abraded (as in a Ball Mill) on the way there.
We haveSmall Ball Mills for sale coming in at very good prices. These ball mills are relatively small, bearing mounted on a steel frame. All ball mills are sold with motor, gears, steel liners and optional grinding media charge/load.
Ball Mills or Rod Mills in a complete range of sizes up to 10 diameter x20 long, offer features of operation and convertibility to meet your exactneeds. They may be used for pulverizing and either wet or dry grindingsystems. Mills are available in both light-duty and heavy-duty constructionto meet your specific requirements.
All Mills feature electric cast steel heads and heavy rolled steelplate shells. Self-aligning main trunnion bearings on large mills are sealedand internally flood-lubricated. Replaceable mill trunnions. Pinion shaftbearings are self-aligning, roller bearing type, enclosed in dust-tightcarrier. Adjustable, single-unit soleplate under trunnion and drive pinionsfor perfect, permanent gear alignment.
Ball Mills can be supplied with either ceramic or rubber linings for wet or dry grinding, for continuous or batch type operation, in sizes from 15 x 21 to 8 x 12. High density ceramic linings of uniform hardness male possible thinner linings and greater and more effective grinding volume. Mills are shipped with liners installed.
Complete laboratory testing service, mill and air classifier engineering and proven equipment make possible a single source for your complete dry-grinding mill installation. Units available with air swept design and centrifugal classifiers or with elevators and mechanical type air classifiers. All sizes and capacities of units. Laboratory-size air classifier also available.
A special purpose batch mill designed especially for grinding and mixing involving acids and corrosive materials. No corners mean easy cleaning and choice of rubber or ceramic linings make it corrosion resistant. Shape of mill and ball segregation gives preferential grinding action for grinding and mixing of pigments and catalysts. Made in 2, 3 and 4 diameter grinding drums.
Nowadays grinding mills are almost extensively used for comminution of materials ranging from 5 mm to 40 mm (3/161 5/8) down to varying product sizes. They have vast applications within different branches of industry such as for example the ore dressing, cement, lime, porcelain and chemical industries and can be designed for continuous as well as batch grinding.
Ball mills can be used for coarse grinding as described for the rod mill. They will, however, in that application produce more fines and tramp oversize and will in any case necessitate installation of effective classification.If finer grinding is wanted two or three stage grinding is advisable as for instant primary rod mill with 75100 mm (34) rods, secondary ball mill with 2540 mm(11) balls and possibly tertiary ball mill with 20 mm () balls or cylpebs.To obtain a close size distribution in the fine range the specific surface of the grinding media should be as high as possible. Thus as small balls as possible should be used in each stage.
The principal field of rod mill usage is the preparation of products in the 5 mm0.4 mm (4 mesh to 35 mesh) range. It may sometimes be recommended also for finer grinding. Within these limits a rod mill is usually superior to and more efficient than a ball mill. The basic principle for rod grinding is reduction by line contact between rods extending the full length of the mill, resulting in selective grinding carried out on the largest particle sizes. This results in a minimum production of extreme fines or slimes and more effective grinding work as compared with a ball mill. One stage rod mill grinding is therefore suitable for preparation of feed to gravimetric ore dressing methods, certain flotation processes with slime problems and magnetic cobbing. Rod mills are frequently used as primary mills to produce suitable feed to the second grinding stage. Rod mills have usually a length/diameter ratio of at least 1.4.
Tube mills are in principle to be considered as ball mills, the basic difference being that the length/diameter ratio is greater (35). They are commonly used for surface cleaning or scrubbing action and fine grinding in open circuit.
In some cases it is suitable to use screened fractions of the material as grinding media. Such mills are usually called pebble mills, but the working principle is the same as for ball mills. As the power input is approximately directly proportional to the volume weight of the grinding media, the power input for pebble mills is correspondingly smaller than for a ball mill.
A dry process requires usually dry grinding. If the feed is wet and sticky, it is often necessary to lower the moisture content below 1 %. Grinding in front of wet processes can be done wet or dry. In dry grinding the energy consumption is higher, but the wear of linings and charge is less than for wet grinding, especially when treating highly abrasive and corrosive material. When comparing the economy of wet and dry grinding, the different costs for the entire process must be considered.
An increase in the mill speed will give a directly proportional increase in mill power but there seems to be a square proportional increase in the wear. Rod mills generally operate within the range of 6075 % of critical speed in order to avoid excessive wear and tangled rods. Ball and pebble mills are usually operated at 7085 % of critical speed. For dry grinding the speed is usually somewhat lower.
The mill lining can be made of rubber or different types of steel (manganese or Ni-hard) with liner types according to the customers requirements. For special applications we can also supply porcelain, basalt and other linings.
The mill power is approximately directly proportional to the charge volume within the normal range. When calculating a mill 40 % charge volume is generally used. In pebble and ball mills quite often charge volumes close to 50 % are used. In a pebble mill the pebble consumption ranges from 315 % and the charge has to be controlled automatically to maintain uniform power consumption.
In all cases the net energy consumption per ton (kWh/ton) must be known either from previous experience or laboratory tests before mill size can be determined. The required mill net power P kW ( = ton/hX kWh/ton) is obtained from
Trunnions of S.G. iron or steel castings with machined flange and bearing seat incl. device for dismantling the bearings. For smaller mills the heads and trunnions are sometimes made in grey cast iron.
The mills can be used either for dry or wet, rod or ball grinding. By using a separate attachment the discharge end can be changed so that the mills can be used for peripheral instead of overflow discharge.
Amidst the general fall in metal prices over the last few years, the gold price has remained comparatively stable in the US$1,000-1,250/oz range. Gold bulls were disappointed that the price did not break through the $2,000/oz ceiling; nevertheless the current stable price run has helped to maintain a strong interest in gold projects.
The second is the sustained, and dare I say sustainable, use of cyanide for gold leaching in the last 100 years or more in a world of increasing environmental concerns and general aversion to the use of toxic chemical like cyanide. Alternatives to cyanide are not the subject of this article, but it is suffice to say that recent applications of alternatives to cyanide, e.g. thiosulfate at Goldstrike Nevada, have been driven by technical rather than environmental imperatives. In the case of Goldstrike, this was a double-refractory ore combining sulphide-occluded gold with preg-robbing carbonaceous material that rendered the ore unsuitable for conventional cyanide leaching and carbon adsorption.
In most cases, gold processing with cyanide leaching, usually with carbon adsorption, is still the core technology and the critical thing is understanding the mineralogy in order to optimise flowsheet selection and cost drivers, and get the best out of the process.
Traditionally, the process selection choice was between a conventional, well-tried, three-stage crushing circuit followed by ball milling, or single-stage crushing followed by a semi-autogenous (SAG) mill and ball mill. The latter is preferred for wet sticky ores to minimise transfer point chute blockages, and can offer savings in both capital costs and long-term operating and maintenance costs. However, the SAG route is more power-intensive and, for very hard ores, comes with some process risk in predicting performance.
Now that initial wear issues have largely been overcome, they offer significant advantages over a SAG mill route where power costs are high and the ore is very hard. They can be attractive too in a heap leach where the micro-cracking induced by the high pressure has been demonstrated in many cases to improve heap leach recovery.
The hashing stage (corresponding to metal extraction and recovery stages) is a little more complex for gold ores, as the optimal process flowsheet selection choice is heavily dependent on a good understanding of two fundamental geometallurgical parameters, the gold mineralogical associations, and the gold particle size and liberation characteristics. These are summarised in Table 2, where the processing options that correspond to the various combinations of mineral associations and liberation are shown along with some examples.
This is common in tropical environments (e.g. West Africa) and typically oxidises gold-bearing sulphides down to 50-100m, transforming commonly refractory gold in sulphides to free-milling gold, behaving in a similar fashion to gold associated with quartz.
Refractory ores are typically treated by flotation and the resulting flotation concentrate may be sold directly to a smelter (common for example in China) or subjected to downstream processing by pressure oxidation or bio-leach.
An ore containing 1% sulphur will produce a mass pull of approximately 5% by weight to a bulk flotation concentrate where recovery is the key driver. If this ore also contains 1g/t Au (for GSR =1), and 90% recovery to concentrate is achieved, then 0.90g will be recovered and with a concentration ratio of 20 (5% to concentrate) this corresponds to 18g/t Au in concentrate.
Both smelter treatment charges and oxidation or bio-leach costs are at least $200/t of concentrate and payables/recovery in the 90% range, so a minimum GSR for effective downstream processing is around 0.5. Clearly this is a function of gold price, but in the current gold price and cost environment, a good rule of thumb is that a minimum GSR of 0.5 is required for downstream processing of a gold-bearing concentrate.
A lower GSR can be tolerated if the flotation concentrate is amenable to direct cyanide leaching without the costly oxidation stage to release the gold from the sulphides. And on-site dor production avoids the off-site costs of transport and smelter charges, but usually with lower recovery (flotation recovery then oxidation-leach recovery) so a trade-off analysis is required.
Smelters typically pay >95% (Au) and 90% (Ag) in copper and lead concentrates, but will only pay 60-70% (maximum, depending on degree of Pb/Zn smelter integration) for gold and silver in zinc concentrates.
It can be seen that the key cost elements are: power, cyanide and grinding steel plus, for refractory ores, the costs associated with pressure oxidation or bio-leaching. It should also be noted that, where cyanide destruction is required (increasingly the norm), then cyanide detox unit costs are usually of a similar order of magnitude to the cyanide unit cost.
In summary, and of particular relevance to project screening, an early appreciation of gold mineralogical associations and liberation can provide considerable insight into metallurgical process flowsheet selection and processing costs.
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Prominer maintains a team of senior gold processing engineers with expertise and global experience. These gold professionals are specifically in gold processing through various beneficiation technologies, for gold ore of different characteristics, such as flotation, cyanide leaching, gravity separation, etc., to achieve the processing plant of optimal and cost-efficient process designs.
Based on abundant experiences on gold mining project, Prominer helps clients to get higher yield & recovery rate with lower running cost and pays more attention on environmental protection. Prominer supplies customized solution for different types of gold ore. General processing technologies for gold ore are summarized as below:
For alluvial gold, also called sand gold, gravel gold, placer gold or river gold, gravity separation is suitable. This type of gold contains mainly free gold blended with the sand. Under this circumstance, the technology is to wash away the mud and sieve out the big size stone first with the trommel screen, and then using centrifugal concentrator, shaking table as well as gold carpet to separate the free gold from the stone sands.
CIL is mainly for processing the oxide type gold ore if the recovery rate is not high or much gold is still left by using otation and/ or gravity circuits. Slurry, containing uncovered gold from primary circuits, is pumped directly to the thickener to adjust the slurry density. Then it is pumped to leaching plant and dissolved in aerated sodium cyanide solution. The solubilized gold is simultaneously adsorbed directly into coarse granules of activated carbon, and it is called Carbon-In-Leaching process (CIL).
Heap leaching is always the first choice to process low grade ore easy to leaching. Based on the leaching test, the gold ore will be crushed to the determined particle size and then sent to the dump area. If the content of clay and solid is high, to improve the leaching efficiency, the agglomeration shall be considered. By using the cement, lime and cyanide solution, the small particles would be stuck to big lumps. It makes the cyanide solution much easier penetrating and heap more stable. After sufficient leaching, the pregnant solution will be pumped to the carbon adsorption column for catching the free gold. The barren liquid will be pumped to the cyanide solution pond for recycle usage.
The loaded carbon is treated at high temperature to elute the adsorbed gold into the solution once again. The gold-rich eluate is fed into an electrowinning circuit where gold and other metals are plated onto cathodes of steel wool. The loaded steel wool is pretreated by calcination before mixing with uxes and melting. Finally, the melt is poured into a cascade of molds where gold is separated from the slag to gold bullion.
Prominer has been devoted to mineral processing industry for decades and specializes in mineral upgrading and deep processing. With expertise in the fields of mineral project development, mining, test study, engineering, technological processing.