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The gold ore heap leaching process is a mineral processing process with a lower cost than conventional cyanide gold extraction, a simpler process, and quicker results. This process is widely used in mineral processing plants. There are many influencing factors in the process of gold ore heap leaching. In actual production, it can only be blamed that if it is not controlled well, it will directly lead to a decline in the beneficiation index and affect economic benefits. The following will introduce ten factors that affect the gold ore heap leaching process.
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If the ore structure is loose, its permeability is better, and the penetration and diffusion speed of cyanide solution is accelerated. Because the gold in the ore is in full contact with the cyanide solution, its leaching speed is accelerated. If the ore structure is dense or the clay is higher, the leaching speed of gold particles is slower. If the ore contains carbonaceous substances, the dissolution rate of gold will decrease during heap leaching, and the activated carbon will adsorb the dissolved gold, reducing the recovery rate of gold. If the ore contains non-noble metal compounds such as copper, lead, and zinc, the dissolution of gold will also be affected. When zinc is used to replace the leaching solution, the leaching effect will be poor and the consumption of cyanide will increase.
Generally, the smaller the particle size of the ore, the faster the leaching speed and the shorter the time required. In actual production, the raw gold ore needs to be crushed to 5-20mm before heap leaching. If the content of 200 mesh in the ore exceeds 35% of the total amount, the conventional heap leaching method will be used, and the powder ore will cause the surface of the ore pile to form a channel, which will affect the penetration rate of the solution and reduce the leaching rate.
The clay content in the ore will affect the leaching rate of gold ore. When the clay is infiltrated by the cyanide solution, the volume expands, the porosity of the ore heap is reduced, and the solution penetration rate is greatly reduced. Therefore, the higher the clay content, the slower the penetration rate of the cyanide solution and the longer the leaching time required.
When low-concentration cyanide solution is used for leaching in the gold ore heap leaching process, the solubility of gold is very high, and the solubility of other non-metals is very low, which can reduce the consumption of cyanide. The main reason is that the dissolution rate of oxygen in it and its diffusion rate in dilute solution are relatively large.
The height of the ore heap will affect the permeability of the ore heap to a certain extent. If the permeability of the ore is good, the height of the ore heap can be appropriately set higher. For the ore with poor permeability, the height of the ore heap should not be too high.
In the gold ore heap leaching process, appropriately increasing the spray intensity can shorten the leaching time and improve the leaching efficiency of gold concentrate. If the spraying intensity is not enhanced, the cyanide will come into contact with the air, resulting in the oxidation of cyanide and loss.
As time goes on, the leaching rate of gold ore will continue to increase, but after reaching a certain level, the leaching rate of gold will decrease as time goes on. There are two reasons. First, during the heap leaching process of gold ore, the gold particles are continuously dissolved, their number and volume are continuously reduced, and their dissolution surface is reduced, resulting in a gradual decrease in the leaching speed. Second, as the gold ore As the leaching time prolongs, the impurities produced during the dissolution process will form a harmful film on the surface of the gold particles, thereby affecting the dissolution rate of gold.
In a cyanidation solution, the concentration of oxygen in the solution will affect the leaching rate of gold ore, the lower the oxygen content in the solution, the slower the gold dissolution rate. Therefore, it is necessary to properly increase the oxygen content in the cyanide solution. During heap leaching, air can be blown into the gold ore heap to increase the dissolution rate of gold and shorten the leaching time.
The dissolution rate of gold in cyanide solution will increase with the increase of temperature. When the temperature reaches 85℃, the dissolution rate effect is better. When the temperature rises above 85℃, the oxygen content in the cyanide solution decreases and the gold dissolution rate decreases. As the temperature increases, the chemical reaction between non-metal and cyanide will also intensify, and the consumption of cyanide will increase. Heating the pulp will increase heat energy consumption and increase production costs.
The presence of argillaceous matter leads to a decrease in the permeability of the ore heap, thereby slowing down the leaching speed of gold ore and reducing the recovery rate of gold concentrate. In order to avoid the influence of muddy matter, it is recommended to pre-granulate the ore and add a small amount of cement, cyanide and alkali. In addition, the desliming process can also be used to detect the influence of muddy matter on the heap leaching effect of gold ore.
The above are ten factors that affect the effect of gold ore heap leaching. In actual production, there may be other influencing factors, and it is necessary to adjust the heap leaching process in time according to the actual production status. Xinhai Mining recommends beneficiation tests to determine the properties of the ore can provide an important basis for the design of the heap leaching process, and a proper heap leaching process can improve the recovery rate and leaching rate of gold, thereby improving economic benefits.