First, reduce the concentration of easily scaled components in the leachate
Such as heap leaching copper and uranium ore with sulfuric acid low as possible, selective leaching, in order to reduce iron, aluminum, calcium, and magnesium ions into solution. When gold ore heap leaching with alkali, caustic soda used for protection of alkali, to reduce the calcium ion, or a strict control of the pH, to reduce the content of carbonate ions.
Second, reduce the amount of water evaporation
Try to keep the surface of the heap moist. The drip leaching method can be adopted. After the mine is built, the drip immersion system is installed and debugged first, and then a layer of fine-grained waste stone of 0.3 to 0.5 m is laid thereon. In arid desert areas, this method is often used due to large evaporation. In areas with low evaporation, in order to maintain the wet state of the surface of the heap, the spray and intermittent time ratio can be appropriately selected according to the nature of the ore, that is, the operation is performed with a small spray intensity and a long spray time. It should be borne in mind, however, that the heap leaching is leached with an unsaturated stream and there must be an intermittent time to allow air to enter the heap.
Third, strengthen the ore and water quality pretreatment
For hard water with high content of heavy bicarbonate, water treatment should generally be carried out to remove calcium and magnesium. Pretreatment of ore should be based on the nature of the ore, but one thing is common, that is, the heap washing water is not recycled unless it is treated. Washing the heap can remove many impurities, which not only reduces the potential for fouling, but also reduces the consumption of the leaching agent. When gold ore is heap leached with sodium cyanide, the consumption of sodium cyanide is greatly reduced when the heap is washed and pretreated.
Fourth, maintain the stability of the solution system
An important practice in this regard is to maintain the pH of the medium. For example, in the acid heap leaching, the pH of the leachate is kept <2; in the alkaline heap leaching, the pH of the leachate is maintained between 9.0 and 0.5. Especially before the peak concentration of the main metal ions in the leachate occurs, the pH should be maintained. In addition, in order to keep the total ionic strength in the solution relatively stable, it is generally possible to change the leaching solution (i.e., reconstitute one part) after the peak concentration occurs, and to treat the portion of the solution containing a large amount of impurity ions after the treatment.
Five, the use of anti-fouling agent
Due to the different nature of the ore, the anti-fouling agent should be selected according to the nature of the ore. At the same time, it is necessary to consider the requirements of the subsequent treatment process of the leachate, and not affect the normal operation of the subsequent treatment process due to the addition of the anti-fouling agent. It must also be pointed out that the part where the anti-fouling agent is added should be selected and the selection site is improperly selected, which not only does not play a role of anti-fouling, but also accelerates the formation of scale.
Almost all of the US gold mine heap leaching uses some anti-fouling agents to prevent scaling in the heap leaching, and the effect is very good.
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