1.Crushing and Grinding
The first step in oxide gold ore processing is the mining of the ore itself, followed by the primary crushing of the gold containing rocks. This step is important because it helps to simplify the material for further processing in other steps. The smaller ore pieces are then transported to a ball mill after the first crushing. In the ball mill, the ore is crushed into fine particles to a size that will allow the gold particles to be easily released from the surrounding material. This fine grinding helps to increase the surface area of the gold ore, thus exposing it to the chemical extraction agents used in the subsequent steps.
2.Screening
After the ore has been crushed and ground to a fine powder, it is conveyed to a vibrating screen. This equipment is used to sort the ore particles by size so that only the right size of particles proceeds to the next step of the process. The vibrating screen effectively sorts the particles and returns the larger ones to the ball mill for further grinding. This helps in making sure that all material is well crushed to the right size that will enhance the recovery of gold. Screening should be done properly to ensure that the next leaching process is efficient and effective.Visit our site to understand how
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3.Cyanide Leaching
In the cyanide leaching stage, the screened ore is taken to large tanks where a cyanide solution is added. This solution leaches the gold out of the finely powdered ore, converting it to a soluble gold-cyanide compound. The leaching tanks are fitted with agitators to enhance the mixing of the cyanide solution with the ore particles to enhance dissolution of gold. This process usually takes several hours, while the cyanide solution leaches gold out of the ore continuously, the aim being to dissolve as much gold as possible into the solution in preparation for concentration and recovery.
4.Thickening
The gold bearing solution from the leaching tanks is then pumped into a thickener where the gold bearing solution is thickened and the solids are allowed to settle at the bottom of the thickener. In this equipment, the solid particles are allowed to settle at the bottom thus making the density of the gold rich solution at the top to be higher. This thickening process is important as it helps to increase the density of the solution in order to ease its handling during the adsorption step. The settled solids or the tailings are also removed and treated at certain intervals of time. The thickener also increases the effectiveness of the entire gold recovery process by concentrating the gold solution.
5.Adsorption
The concentrated gold solution is then treated through activated carbon columns. Activated carbon has a large surface area and a high selectivity for gold, which enables it to selectively adsorb gold from the solution. When the solution passes through the columns, the gold particles stick to the carbon media and thus, are separated from the liquid. This adsorption process is very efficient and can recover a lot of gold from the solution as shown in the following equation. When the carbon is saturated with gold, it is taken out of the columns for other treatments to be made on it.
6.Desorption and Electrowinning
In the desorption stage, the gold adsorbed on the carbon from the adsorption columns is treated to release the gold into a concentrated solution. This is done by heating the carbon and then applying a chemical solution that will release the gold. The gold-rich solution is then taken to electrowinning cells where an electrical current is passed through it. This current deposits the gold onto cathodes and thus recovers it from the solution in the present case. Electrowinning is a very efficient process and the product obtained is very pure gold which can be further purified.
7.Smelting
The gold that is obtained from the electrowinning process is then subjected to smelting process in a smelting furnace. This high-temperature furnace melts the gold, so that it can be easily separated from other impurities and other metals. The molten gold is then cast into molds to make gold bullion bars. Smelting is important because it helps to ensure that the gold is in its pure form and ready for the market. The gold bars produced are weighed and checked for purity before they are forwarded to the last refining process.
8.Refining
The last step of refining is further melting and chemical processing to get the gold as pure as it can be. This process also helps to eliminate any remaining impurities and thus the gold produced is of the required standard. Refining can be done through several processes such as acid treatment, electro refining and other chemical processes. The result is gold that is 99. Concentrations of 99% pure or higher for sale in the market or for industrial use. The purified gold is then poured into bars, ingots or any other shape that is preferred.
9.Tailings Management
During the various processing stages, there is production of waste material referred to as tailings. Tailings management is the process of safely storing or disposing of this material so as to reduce the effects on the environment. This may involve building tailings dams where the tailings are contained in a basin or reprocessing the tailings to recover any remaining minerals. Appropriate handling prevents the tailings from polluting water or soil in the vicinity, complies with the environmental requirements, and minimizes the impact of the mining process on the environment.
