Six Essential Experiments for Gold Mine Leaching

Cyanidation leaching is one of the primary methods for extracting gold from gold ores. For the treatment of gold-bearing ores using the cyanidation leaching method, the recovery rate of cyanidation leaching mainly depends on the effect of the leaching operation. To ensure the overall cost of the concentrator and improve the technical and economic efficiency of the concentrator, it is necessary to determine how to adopt a reasonable leaching process and equipment and select appropriate leaching conditions through gold leaching experiments. The test items selected for gold leaching experiments are roughly the same as the factors affecting gold leaching. The process of gold leaching experiments mainly includes the following aspects: 1. Grinding fineness test, 2. Pretreatment enhanced leaching test, 3. Protecting alkali dosage test, 4. Leaching agent test, 5. Pulp density test, 6. Leaching time test.

Grinding Fineness Test

For cyanidation leaching, it is a necessary condition that gold should be in contact with reagents after monomer dissociation. Grinding fineness is a key factor affecting the monomer dissociation of minerals. To ensure high cyanidation indexes, it is necessary to study the influence of mineral particle size on cyanidation leaching so as to determine the appropriate grinding fineness according to the mineral properties. The dissociation of minerals is a key issue that needs to be solved before any mineral processing method. Only when the selected minerals can be completely or mostly monomer-dissociated can a high recovery rate be ensured and the loss in the tailings be reduced as much as possible. However, it should be noted that over-grinding should not be pursued excessively, as this will not only increase the grinding cost but also increase the possibility of impurities entering the leaching solution. At the same time, it will make the solid-liquid separation difficult and cause the loss of cyanide and dissolved gold. Therefore, the grinding fineness needs to be further determined through leaching experiments.

Pretreatment Enhanced Leaching Test

Associated minerals dissolve to varying degrees in cyanide solution, which has an adverse effect on the leaching of gold. For this type of gold ore, pretreatment is required during leaching. Adding an oxidant for oxidative pretreatment of gold ore can effectively improve the leaching rate of gold in the gold ore. Common pretreatment agents for gold ore leaching include calcium peroxide, sodium hypochlorite, sodium peroxide, hydrogen peroxide, citric acid, lead nitrate, etc. Usually, the leaching effect after pretreatment of gold is compared with that without adding a pretreatment agent under normal conditions. The purpose is to determine whether a pretreatment operation is necessary.

Protecting Alkali Dosage Test

In order to protect the stability of the sodium cyanide solution or the gold extraction agent and reduce the chemical loss of the gold extraction agent, an appropriate amount of alkali must be added during leaching to maintain a certain alkalinity of the pulp. Within a certain range of alkalinity, with the increase of alkali concentration, the gold leaching rate remains unchanged while the dosage of the gold extraction agent decreases accordingly. However, if the alkalinity is too high, the dissolution rate and leaching rate of gold will decrease instead. Therefore, it is necessary to determine the appropriate dosage of protecting alkali and the pulp pH value. In experiments and production, lime, which is widely available and inexpensive, is usually used as the leaching protecting alkali to determine its specific usage amount, providing guidance for actual production.

Gold Extraction Agent Dosage Test

In the leaching process, within a certain range, the dosage of the gold extraction agent is directly proportional to the gold leaching rate. However, when the dosage of the gold extraction agent is too high, not only will the production cost increase, but the change in the gold leaching rate is not significant. Therefore, on the basis of the grinding fineness test, in order to further reduce the dosage of the gold extraction agent and the production reagent cost, a gold extraction agent dosage test is carried out to determine the appropriate dosage.

Pulp Density Test

The pulp density will directly affect the leaching rate and leaching rate of gold. The higher the pulp density, the worse the fluidity, and the lower the leaching rate and leaching rate of gold. When the pulp density is low during leaching, the fluidity of the pulp is good and the gold leaching rate is high, but the dosage of the reagent will increase exponentially, and the equipment volume and investment cost will also increase accordingly. Therefore, in order to balance the gold leaching rate and production cost, an appropriate leaching pulp density is required.

Leaching Time Test

Leaching time is one of the important factors affecting gold leaching. During the leaching process of gold, as the time prolongs, the gold leaching rate gradually increases. However, due to the saturation of the gold surface and the gradual increase in the thickness of the solution layer, the leaching rate is constantly decreasing, and the leaching rate gradually tends to a constant value. It is very important to clarify the appropriate leaching time in the cyanidation leaching process. If the leaching time is too short, the gold minerals cannot be fully dissolved and leached. If the leaching time is too long, not only will larger process equipment and sites be required, but also other impurities in the pulp will continue to dissolve, thus hindering the dissolution of gold. Therefore, it is necessary to determine the appropriate leaching time through leaching experiments to improve the leaching work efficiency.

In conclusion, these six essential experiments play a crucial role in optimizing the gold mine leaching process. By carefully conducting these experiments, miners can make more informed decisions, improve the efficiency of gold extraction, and reduce production costs.