small washing plants diamonds

diamond processing flow chart of beneficiation

diamond processing flow chart of beneficiation

World demand and production of diamond both for gem and industrial purposes has increased nearly five-fold during the past 25 years. Improved mining and recovery methods together with the discovery and development of new fields has enabled mining operations to fill the growing demands. Producing areas in Canada, South Africa, South West Africa, The Congo Republic, Angola, Ghana, Tanganyika and Sierra Leone account for over the bulk of world production.

In mining, diamonds are recovered mainly from alluvial deposits which vary widely in character, often cemented; and usually contain large quantities of clay or a sticky slime fraction from near zero to about 50%. Substantial production also comes from Kimberlite pipes and dikes (Blue Ground), a basic igneous breccia, considered generally to be the originating source for nearly all diamonds. Diamonds have a specific gravity up to 3.52and are associated with minerals such as magnetite, ilmenite, garnet, tourmaline, spinel, rutile, pyrite, quartz and other minerals which due to their specific gravity makes separation from the diamonds difficult and affects the ratio of concentration obtainable through gravity methods. Since the value per ton of diamondiferous gravel seldom exceeds one metric carat per ton with an average of less than 0.3 carat, a high ratio of concentration, in the order of 1: 5,000,000 or higher, is necessary.

Many recovery methods are used and methods vary depending on the location, size and nature of the deposit. The methods include production by natives using simple hand pans to more complex mechanical means employing washing, screening, stage crushing, clear water and puddle panning, heavy media separation, jigging, attrition and differential grinding, magnetic and/or electro-static separation, flotation, grease tabling and hand sorting. Certain operations use one or more field plants to supply a central plant for reconcentration and final sorting.

This flowsheet is typical for small to medium tonnages of alluvial feed (5 to 30 tons per hour). Such material is often cemented and requires crushing by either jaw or gyratory crushers. In this flowsheet a trommel screen, with a scrubbing section, is used to break down clay and cemented fractions, before screening and rejection of the oversize to waste. The trommel undersize, 1, is fed to centrifugal diamond pans in series.

Diamond pans were developed in South Africa and have been highly successful and widely used in the recovery of diamonds. Their use for the separation of other minerals has been limited and inefficient.

A diamond pan is a shallow, flat bottomed circular pan with an inner well about 0.3 of the pan diameter and several inches lower in height than the outer pan wall. A vertical shaft is mounted to rotate in the center to which radial horizontal arms are attached above the pulp level in the pan. Tines extend downward from the radial arms and are adjustable to clear the pan bottom. These tines are triangular and so spaced and mounted on the radial arms to plow material on the pan bottom outward. The feed entry is tangential to the outer wall while the tailings discharge is through a weir in the center well. In operation the tangential entry of the feed combined with the stirring action of the tines causes a vertical swirl to the mass. The condition created in the pan simulates the heavy media process in that the lighter materials remain in suspension and are carried down the vortex to the center discharge weir while the heavier particles settle through the swirling mass to be plowed outward on the bottom to a concentrate discharge outlet in the outer wall. Feeds containing a high amount of clay and fine sands give the most effective results, however, many pans operate on feeds containing little or no clay or fines with reduced but still satisfactory recoveries. Capacity of diamond pans is normally 5 to 6 tons per square foot of effective area per 24 hours and require 1 to 1 horsepower per ton of feed. Ratios of concentration vary, usually from 10:1 to 50:1 depending on the amounts of heavy minerals associated with the diamonds. Recoveries up to 97% are sometimes possible.

The diamond pan concentrates in Flowsheet No. 1 are elevated to a trommel screen for sizing to eliminate 16 mesh undersize and to produce four size ranges each going to a Duplex Mineral Jig for further concentration.Mineral Jigs have proven to be very efficient in diamond treatment with recoveries near 100% being reported. The jigs are equipped with 2 mm bedding screens. No artificial bedding is added in most operations since the pan concentrates contain sufficient heavy minerals to form adequate bedding. A 2-mm hutch concentrate is produced from the jigs which are discharged to locked containers before being removed to the final recovery section. The 2-mm concentrate retained on the jig screens is removed by hand at intervals as necessary and are hand sorted for recovery of the diamonds. All phases of concentrate handling are done under conditions to insure security. All launders, jig compartments and concentrate collection points are covered, locked or protected to prevent theft.

This flowsheet was developed for diamond recovery from Kimberlite ore as mined and with properly sized equipment is suitable for tonnages up to 50 tons per hour. The mined ore is crushed to 3 followed by screening and secondary crushing to 1. A picking belt is sometimes employed between crushing stages for removal of waste rock and possible recovery of large diamonds, but this step is generally considered uneconomical. Few, if any diamonds are broken in the crushing operations, as they are usually smaller than the crusher openings, and break free from the matrix without damage. The crushed ore goes to a bin for storage and for controlled feeding to the recovery circuit. A trommel screen with scrubbing sections is used to break down any soft portion of the ore before screening. Oversize material is reduced to 1 with a spring roll crusher and then joins the trommel undersize to feed a centrifugal diamond pan. The flowsheet shows one pan, however, several pans in series are sometimes found to be more effective when the ore contains high percentages of heavy minerals. The pan tailings are elevated or dewatered and conveyed to another screening and crushing step to provide a3/8 feed to asecondary diamond pan. The tailings from the secondarypan are elevated and screened to produce a + 1/8 fraction as a final tailing, and a 1/8 product which passes to a Duplex Mineral Jig for recovery of any small diamonds remaining. The concentrates from the primary and secondary pans are each separately fed to two Duplex Mineral Jigs in series for reconcentration. The use of Mineral Jigs in series on the unclassified feed eliminates the necessity of classification or screening to produce sized feedfractions often necessary when plunger type jigs are used. The ratio of concentration on jigs in this service ranges from 10:1 upward depending on the amounts of heavy minerals in the pan concentrates. Feed rates vary from 200 to 1000 pounds per square foot of compartment area per hour.

The final recovery of the diamonds from gravity concentrates is accomplished by several steps of reconcentration which differ in many cases due to the amount and nature of the associated gangue minerals. When appreciable amounts of heavy minerals are present the concentrates are sized to give a 1/8 fraction which is dried and passed through magnetic and/or electrostatic separators to eliminate affected materials, before being further reconcentrated on grease tables. The recovery method shown in Flowsheets No. 1 and No. 2 is frequently used when the gravity concentrates are wet screened to three or more size ranges as the feed to separate grease tables and to reject 16 or 28 mesh materials.

The grease tables are of several types being usually either mechanically or electrically vibrated with the movement normal to direction of flow. The decks are made both flat and stepped, being adjustable in slope to give proper flow velocity for the different size ranges of feed. The stepped decks have from 4 to 8 removable compartments or pans each being 8 or more in width by 3 to 4 feet in length, each pan being mounted in steps down the table. Each step is coated with + thickness of a special petroleum grease which is given a surface covering of about 1/16 of another type grease. In operation the sized feed is uniformly fed across the table into a flow of water to carry the material across and down the table steps. The diamonds being non-wettable adhere to the grease while most of the other minerals are carried off the table by the water and are rejected as waste. After 45 to 60 minutes of operation the 1/16 surface layer of grease, together with the diamonds and some other trapped minerals, are scraped from the tables. This grease layer is placed in grease pots having perforated sides. The pots are

covered and placed in boiling water for removal and recovery of the grease. The diamond concentrates after degreasing are hand picked and sorted under diffused light. This final operation is very exacting work and is carried on under close observation and security conditions.

This flowsheet illustrates a more complex diamond recovery method developed in recent years. With variations it can be used to process 100 to 500 tons per hour of Kimberlite ore and is also arranged to handle weathered or soft ores. For the hard ore as mined the flowsheet follows conventional methods of stage crushing and screening to reduce the ore to . The weatheredore is intensely scrubbed to break down the soft fractions and then screened as shown. All the 1 ore is wet screened to produce +10 mesh and 10 mesh sizes. The 1, +10 mesh fraction goes to a heavy media separator from which the sink product, after media screening and washing, goes to concentrate storage. The float product is washed and screened to reject all 3/8 to waste. The +3/8 size is crushed and screened to 3/8 +10 mesh for retreatment to the heavy media circuit.

All 10 mesh material from the screens ahead of the heavy media process and from the screen following the scrubber is dewatered and wet screened to give a 10 mesh, +16 mesh size range for treatment either by heavy media separation through cyclone separators or by Duplex Mineral Jigs as illustrated.

In the recovery section a number of reconcentration methods are used. Attrition grinding using a light grinding charge at near 40% of critical speed reduces part of the heavy minerals without damage to the diamonds. The mill discharge is screened to eliminate 16 mesh or in some cases 28 mesh and to split the remaining concentrates at about 7 mesh. These two size ranges being treated separately with the 7 mesh going to a mill to effect a differential grind to further reduce the waste materials. This product is wet screened and the oversize is dried, screened to remove dust before passing through an electrostatic separator. The diamond concentrates are then hand sorted. The +7 mesh concentrates are sized, usually to four size ranges, each separately conditioned to remove any coating from the diamonds which interfere with collection on grease tables or grease belts. Grease belts are a recent development and require less attention and labor than grease tables. They are similar to short conveyors and are mounted in a framework so that the slope can be adjusted for correct flow velocity. The concentrates are fed to spread a thin layer over the belt surface down which a stream of water flows. Grease is continually applied to the belt at the upper end and is scraped off at the lower end with the diamonds. The diamonds are degreased and processed by hand sorting.

exclusive: fraser alexander dominates coal washing in southern africa

exclusive: fraser alexander dominates coal washing in southern africa

Fraser Alexanders minerals processing business, which focuses primarily on coal washing, has become a significant market leader in the South African coal mining industry since its formal establishment in 2005.

Looking to the future, the company intends to further enhance this position by doubling its revenue within the next three to five years, minerals processing general manager Jaco Scholtz tells Laura Cornish.

Thanks to our unique service offering and highly skilled workforce, we have grown significantly over the last 12 years, an achievement we are particularly proud of considering the industry has been in recession for a number of years. And we are bullish for the future, Scholtz notes.

In addition to expanding its business in South Africa, the company has significant appetite to build its presence in Botswana (where it operates a local company) which has added at least four potential opportunities to the project pipeline.

It has the capacity to provide the operation and maintenance (O&M) of existing wash plants; or to build, own, operate and maintain (BOOM) or build, own, operate, maintain and transfer (BOOT) the wash plants.

The companys service offering covers the entire coal processing value chain; which includes crushing and screening, heavy media separation, fine coal treatment, flotation and filtration, as well as briquetting.

In support of its O&M/BOOM/BOOT service offering (which covers all maintenance, spare parts and capital items replacement over the contract period), Fraser Alexander is able to de-risk new projects further by providing upfront finance to cover the design and construction costs as well.

Fraser Alexanders wash plants range in size from 200 tph to as much as 600 tph although Scholtz notes the companys plant capacity capabilities are not size constrained due to their modular construction.

Monthly management committee audits are also conducted to measure all key areas of plant operation safety, operations, maintenance, finance and human resources to ensure they are delivering a consistently optimal performance.

Our operations regularly achieve benchmark up-time on-coal hours, with more than 92% availability and more than 600 running hours per month. This level of up-time is unparalleled in our industry, Scholtz notes.

Besides mineral processing/coal washing, Fraser Alexander also offers various other, outsourced services across the mining value chain including construction and bulk engineered earthworks, mining and re-mining, materials handling, tailings and discard deposition, water treatment and rehabilitation.

explorer portable plants | portable wash plants | dove

explorer portable plants | portable wash plants | dove

Potable Wash Plants, also known as Portable Gold Wash Plants, Portable Diamond Wash Plants, Small Gold Wash Plant, Portable Gold Mining Equipment, Portable Gold Mining Wash Plants, Small Gold Mining Equipment, or Portable Gold Trommel Wash Plants

The EXPLORERPortable Processing Plants are Portable Wash Plants exclusively designed, patented and developed by DOVE, for surface mining in exploration, pilot and small scale mining operations of alluvial Gold, alluvial Diamond, Gemstones, base metals metals and ferrous metals.

EXPLORERPortable Plants are configured and customized with multy-stage classifier and concentrators according to the ore specification as a fully integrated processing plant for 100% recovery of gold, diamonds, base metals, ferrous metals, with no loss.

EXPLORER Portable Plants are easily assembled, disassembled, installed and transported through the mining site, resulting in rapid deployment on the site. Plants are fully portable to allow ease of movement in the field.

EXPLORER Portable Plants offer features such as the ability to easily be operated and maintained on the site, and dont require much human interference during the processing of the minerals, offering a user-friendly experience for the operator.

EXPLORER Portable Plants can be tailor made according to the mine specifications and customized to be integrated with various portable equipment in order to form a complete production line for the full recovery of minerals.

EXPLORER Alluvial Gold Processing Plants are configured with our special Multi-Stage Classification Trommels, which enables the plant to achieve up to three (3) sizes classification simultaneously as well as resolving the Heavy Clay content concern, Duplex Jig Concentrators and DOVE Centrifugal Gold Concentrators, which will ensure that the processing of the ore will capture both gold nuggets and fine gold with no loss, down to 40 microns (0.040mm), with 100% recovery.

EXPLORER Alluvial Diamond Processing Plants are configured with our Trommels Classifier Screens/Scrubber Screens, which enables the plant to thoroughly wash the ore and break the host clay if necessary, Duplex Primary and Secondary Jig Concentrators, and Scavenger Jig Modules for the simultaneous processing, concentration and separation of coarse and fine diamonds, with 100% recovery.

EXPLORER Alluvial Gold and Diamond Processing Plants are configured with our special Multi-Stage Classification Trommels, which enables the plant to achieve up to three (3) sizes classification simultaneously as well as resolving the Heavy Clay content concern and liberate the gold and diamond from the host clay, Duplex Primary and secondary Jig Concentrators for the recovery of gold nuggets and coarse diamond particles, Scavenger Jig Modules for the recovery of fine Diamond Particles, and DOVE Centrifugal Gold Concentrators for the recovery of fine gold. The plants are designed to achieve 100% recovery of Gold and Diamonds particle, down to 40 microns (0.040mm), with no loss.

DOVE laboratory will assay your ore samples rapidly and analyze your raw materials and recommend the most efficient processing plant according to the ore specifications, minerals composition, and ore assay results, and your project size and the geologic and topographic conditions of your mine.

henan mining machinery and equipment manufacturer - diamond and gemstone washing plants

henan mining machinery and equipment manufacturer - diamond and gemstone washing plants

SUPERMINER Wash Plants, Portable Gravity Separation Plants are designed, ... including Diamond, Color Gemstones, Gold, Base Metals, Ferrous Metals, ...used small scale gold wash plants | Mobile Crusher for sale. Gold Mining Equipment Solutions for Maximum Mineral Recovery. ... diamonds, as well as other gemstones ...

Ore beneficiation equipment, sand making equipment, crushing equipment and powder grinding equipment, which are widely used in various industries such as metallurgy, mine, chemistry, building material, coal, refractory and ceramics.

portable processing plants | portable wash plants | dove

portable processing plants | portable wash plants | dove

The SUPERMINER Processing Plants are Portable Wash Plants exclusively designed, patented and developed by DOVE Equipment & Machinery Co., Ltd., for surface mining in medium and large scale mining operations of alluvial Gold, alluvial Diamond, Gemstones, and other Alluvial (Placer) metals and minerals.

SUPERMINER Portable Plants offer features such as the ability to easily be operated and maintained on the site, offering a user-friendly experience that requires no expertise and only one day of training.

SUPERMINER Portable Plants are easily assembled, disassembled, installed and transported through the mining site, resulting in rapid deployment on the site. Plants are fully portable to allow ease of movement in the field.

SUPERMINER is a Portable Wash Plant (Processing Plant) exclusively designed, developed and patented, with the latest minerals processing technology by DOVE, and supplied in various integrated configurations for efficient and professional Alluvial mining operations of gold, diamonds and other metals and minerals.

SUPERMINER Alluvial Gold Processing Plants are configured with our special Multi-Stage Classification Trommels, which enables the plant to achieve up to three (3) sizes classification simultaneously as well as resolving the Heavy Clay content concern, Duplex Jig Concentrators and DOVE Centrifugal Gold Concentrators, which will assure that the processing of the ore will capture both gold nuggets and fine gold with no loss, down to 40 microns (0.040mm), with 100% recovery.

SUPERMINER Alluvial Diamond Processing Plants are configured with our Trommels Classifier Screens/Scrubber Screens, which enables the plant to thoroughly wash the ore and break the host clay if necessary, Duplex Primary and Secondary Jig Concentrators, and Scavenger Jig Modules for the simultaneous processing, concentration and separation of coarse and fine diamonds, with 100% recovery.

SUPERMINER Alluvial Gold and Diamond Processing Plants are configured with our special Multi-Stage Classification Trommels, which enables the plant to achieve up to three (3) sizes classification simultaneously as well as resolving the Heavy Clay content concern and liberate the gold and diamond from the host clay, Duplex Primary and secondary Jig Concentrators for the recovery of gold nuggets and coarse diamond particles, Scavenger Jig Modules for the recovery of fine Diamond Particles, and DOVE Centrifugal Gold Concentrators for the recovery of fine gold. The plants are designed to achieve 100% recovery of Gold and Diamonds particle, down to 40 microns (0.040mm), with no loss.

DOVE laboratory will assay your ore samples rapidly and analyze your raw materials and recommend the most efficient processing plant according to the ore specifications, minerals composition, and ore assay results, and your project size and the geologic and topographic conditions of your mine.

diamond final recovery plants - manhattan corp

diamond final recovery plants - manhattan corp

Flow Sort technology was established in 1971. There are a few variants available designed to suit different applications. For final recovery one can select a single stage or double twin stage machine. The twin stage machine has two ejectors so each diamond has two chances of being detected, improving machine efficiency. Flow Sort reports up to 98% recovery with their technology. Manhattan has built final recovery plants with 1,2,4 and 8 machines mounted in different configurations as per client requirement.

Typically a complete plant requires a front end washing circuit followed by a scalping screen with storage bins. A conveyor then feeds the X-Ray units from each storage bin, with predetermined size-restricted material to enable optimal recovery efficiency. Automation of the plant to make it hands free is one of the features offered by Manhattan.

The Russian Bourevestnik machine is an alternative to the South African Flow Sort technology option and diamond sorting equipment have been available since 1969. Both Bourevestnik and Flow Sort also offer bulk sorting options as concentrating plants. Both companies offer 1mm to 50mm final diamond recovery.

Due to a diamonds hydrophobic nature, diamonds stick to diamond grease. Manhattan offers conventional grease table plants with pre-washing, scrubbing if required, and classification into different sizes, before processing over grease. This manual plant can also be offered in a hands-free version with a grease belt, somewhat like a wide conveyor belt, with grease removal, melting, recovery of diamonds and re-application of grease to the belt in an automated hands-free circuit. Diamonds are recovered from the drop box with limited gangue material, which is then hand sorted to recover the diamonds.

XRT units can act as final recovery units. Typically they are similar to the bulk sorters but configured in final recovery mode. They are more expensive than conventional final recovery X-Rays. Certain diamonds, those with coatings or low fluorescence may benefit from an XRT final recovery instead of a conventional fluorescing X-Ray unit.

Small scale operators often select a bush jig to re-concentrate their rotary pan plant product. Manhattan offers both the simple bush jig and also a 2 stage high tph jigging plant. The advantage being its higher capacity and the fact that is fed with a machine and not by hand. The material would be washed, pre-classified and fed to a rougher and cleaner jig providing a small mass pull more suitable for final X-Ray recovery or hand-sorting.

Many operators utilize a DMS to perform this function but as a jig utilizes water as its concentrating medium instead of ferro silicon, it is far cheaper to operate and has a lower energy consumption. It can also manage a large size range of diamond sizes unlike small tph DMS. Of course the capital cost is also far less than a DMS.

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