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The jig consists of a bucket like container with a 3mm screen fixed at the top. It has a manual handle used to jig the bucket. For physical separation, the bucket is filled with ore material, and then immersed in a drum of water and jigged manually. The shaking movements in the water currents push the light material out of the bucket. The oversize and heavy material will remain in the bucket and removed by hand .
This technology involves leaching the gold concentrate with dilute hydrochloric acid and bleach. After the solids are filtered, the gold is precipitated out with sodium metabisulphate. Gold concentrate (ideally grade >1000g/t) is digested in hyperchlorite, the filtrate contains gold in solution, gold is precipitated using sodium metabisulphite, the fine gold can be cut in a small die to produce a rough coin. Purity of gold can be as high as 99.9%. Developed in 2006, and piloting took place between 2007 and 2012 in South Africa, Peru, Mozambique, and Tanzania. There are no records of the technology being currently used.
This is a centrifugal concentrator that takes milled and screened ore and separation medium is water. Rotating cone (polyurethane lined) receiving prescreened feed material. Water is applied to the feed onto the screen. The lighter material is washed down as tailing and the concentrate remains in the riffles of the cone for the washing down process to go into a hopper, where it is collected for further upgrade. Estimated recoveries of between 70 and 75%.
The Gold Konka consists of several sluices connected in a zig-zag pattern. The sluices are lined with vortex mats. The material is fed manually into the top sluice and washes down several sluices (i.e., usually four in the processing system). After a batch is complete, sluice modules are washed down into a container to release the concentrate for further upgrade .
This is a centrifuge consisting of a rotating bowl fitted with a series of ridges/riffles. Material is fed as a mixture of milled rock and water into the rotating bowl. Heavy minerals are trapped on the riffles as the bowl spins. Once a batch is complete, the concentrate is rinsed out for further upgrading .
The Gemini shaking table is made of fibreglass that is supported by steel frame. It has an adjustable tilt and one direction shaking movement with variable speed. The table has recessed grooves that collect gold. The material is fed onto the table through the hopper. Physical separation is achieved by shaking movements and continuous supply of water at constant pressure to the main manifold in the centre. Shaking moves the material forward, water washes the light material outwards and dense material remains. Three products are produced, concentrates, middling and tailings. The middling fractions may be re-processed to upgrade into concentrate .
The bowl is a plastic dish with water entry at the bottom and a central column through which water and suspended material is washed away. The feed material is added into the dish. As water is introduced in the bowl, it creates a vortex that suspends the light material in the ore and eventually washes it off. The heavy material remains in the dish .
The method is based on the cyanidation process to recover the gold from the ore. Instead of using the traditional cyanide chemical reagent, the method starts with the extraction of glycosides from cassava, which are converted into cyanide through the process of hydrolysis (Torkaman et al, 2021).
This leaching process uses a mixture of cyanide and glycine to recover gold from the ore. Glycine is an amino acid that bonds well with minerals that are difficult to separate from the gold using the cyanidation process. Glycine bonds well with copper leaving cyanide to leach gold from gold-copper concentrates.
It consists of a rotating bowl with a central feeder. The inside of the bowl is lined with rubber riffles. The pre-screened feed enters the feeder from the top with wash water. The rotating bowl causes the slurry to travel upward along the inside of the central feeder into the bowl. The heavy material settle underneath the riffles and the light material are washed over the rim. When the riffles are full, the concentrate is washed out (Grayson, 2007).
The process involves direct smelting of the gold concentrate to produce a doré. Smelting can be done with any flux, however Borax (sodium tetraborate) is the most commonly used. To start the process, clean concentrate is mixed with borax and water in a plastic bag, which is then placed into a crucible. Once in the crucible, it is heated with charcoal and a gas torch. Portions of borax are added into the crucible as heat is applied. This is so that, borax lowers the melting point of the mineral impurities in the concentrate to separate them from gold. The process can also be carried out using a furnace. With this route, a crucible with the concentrate and flux are place inside the furnace. After heating the crucible, the molten concentrate is poured into a cupel. The gold will sink to the bottom with a layer of impurities at the top. Once it has cooled and hardened, the slag is crushed with a hammer to release the gold bead (Telmer and Stapper, 2012).
The process extracts the gold through the use of thiosulphate as the leaching lixiviant. The feed material is crushed and grinded to the required particle size. It is then dewatered to prepare for leaching. The thiosulphate reagent is mixed with water. The solution, ore and resin are added into tanks for leaching to take place. After a set time, the solution is screened to collect the resin and to filter the ore from the solution. This is followed by elution and precipitation of the gold for smelting .
The CGA takes advantage of the hydrophobic (resists water-wetting) and oleophilic (easily wetted by oils) properties of gold to separate it from other minerals. The process starts with creating the coal-oil agglomerates, which are then added into a reactor with slurry ore. By use of intensive agitation, the gold particles will collide with the agglomerates, eventually attach and penetrate them. This process continues until the target concentration is reached. The recovery of the gold is either by flotation or drying and burning the agglomerates to extract gold .
The concentrator consists of a cone shaped rotating bowl with a feeder vessel at the centre. The outer extremities of the concentrate bowl house a series of ribs, and between each pair of ribs is a groove. The concentrator has discharge pipes for tailings and the concentrate as well as water inlet pipe connected to a series of tangential water inlets along the perimeter of each groove. The feed material is fed into the feeder vessel as a slurry and when coming into contact with the base plate of the vessel, it is thrust outward into the cone. As it rotates, the light material flows upwards over the grooves heavy material are trapped by the grooves. Pressurised water is injected to maintain a fluidized bed of particles in which heavy mineral particles can be efficiently concentrated (Grayson, 2007)
The technology comprises of a feed hopper connected to a column with pipe slots and gold collecting jar. The process uses elutriation, where the feed material is fed from the top through the hopper and the water injected in an opposite direction to replace the light material from the heavy particles. As the separation takes place, the tailings are washed out into a bucket and the gold falls down into the collection jar .
It is a leaching process that uses two reagents (i.e., proprietary) to extract gold from the ore. After crushing, the feed material and the leaching solution are added into a tank and stirred, for about an hour. This is followed by filtering to separate the ore from the pregnant solution. The solution is added into a column with resin, which separates the gold and silver as the target minerals .
This is an integrated technology that consists of several components; hopper, feed conveyor, scrubbing trommel, spiral concentration belt, tailings and concentrate sluices. The feed material is fed into the hopper and moves on the conveyor belt at a required feed rate. It then enters the scrubbing section of the trommel where it is washed and then screened. The oversize tailings are discharged, and undersize material drops into the concentration belt. The belt continuously fluidises the material separating the light material from the heavy particles. The light material then flows over the tailings sluice and the heavy material over the concentration sluice. The sluice mats are then taken out for concentrate cleaning .
The Haber Gold Processor (HGP) follows the vat leaching process. After size reduction, classification and pre-treatment (i.e., if required), the feed material mixed with water is pumped into tanks. The leaching solution (e.g., it is not disclosed) is then added to facilitate leaching. To recover the gold, the pregnant solution is pumped into the recovery processor, where the HGP4 solution is pre-mixed, added and stirred into the solution. This will cause the gold to precipitate out of the solution. A filtration system is then used to capture the powdered gold .
The Cleangold sluice consists of polymetric magnetic “blue” sheets inserted in aluminium sluice. The method uses magnetism to create rifflers for physical separation of gold from material with lower density. The ore should either contain magnetically susceptible components, or recyclable magnetic material can be added. For physical separation, the ore and water are passed through the sluice. The sheets will attract and hold the magnetic material in the ore, creating a pattern similar to the corduroy cloth. The heavy minerals will settle in the riffles of the pattern. to recover the gold, the magnetic layer with gold particles will be scrapped off into a pan for cleaning.
Cyanide tank leaching requires one or more large above ground tanks. These can be made of local bricks and plastered on the inside for waterproofing. The tanks are usually about 2 meters deep and 4 to 6 meters in diameter. They hold between 50 and 80 tonnes of ore. Often there are up to 6 tanks. Ideally this is located on the slope of a hills so that the leachate can flow with gravity. This system works for fine ore, often too fine to be separated out using gravity or centrifugal force. (Contributed to the Atlas by Peter Lattey)
This is a proposal only. We have not yet built this system. We are submitting it to get feedback and suggestions from people before we do build it. If there is an organization that would like to help fund this we would be happy to talk with them. A conventional CIP system consists of several large tanks with agitators and air pumps. The ore slurry consists of finely ground ore, cyanide solution and carbon. Our proposed system has several key areas that differ from a CIP system. These are: 1. The agitation of the ore/cyanide slurry is done in a rotating drum mixer. Specifically, this is a concrete mixing unit that is normally mounted on a Redimix delivery truck. This mixes and aerates the slurry using a single motor. These units are available in most countries, either new or used. 2. The flow of the slurry and leachate through the system is by gravity. The gold producing area in Masara, Kenya is rolling hills so this system uses the natural slopes to operate. 3. The carbon is placed in a separate, secured chamber and the pregnant leachate passes through it by gravity feed. The leachate can be tested before and …
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