The heap leaching method is one of the gold ore beneficiation methods. It is an effective method for selecting low-grade gold mines. What are the factors that affect the gold extraction by the heap leaching method?
The gold extraction by heap leaching method is to accumulate gold ore with a certain particle size on a leakproof bottom mat paved with asphalt, concrete or plastic, spray the cyanide solution from above to dissolve the gold, and then extract it by chance Withdraw funds. The heap leaching method has the advantages of short process, low cost, easy operation, and quick results. Therefore, it has been widely used in the gold selection industry. However, the heap leaching method is affected by many factors. If it is not handled properly, it will easily lead to problems such as production failure and process accidents, which will affect the beneficiation benefit.
The following is a brief description of the influencing factors of gold extraction by gold leaching equipment heap leaching from four aspects: ore, leachate, spray and heap leaching:
1. The impact of ore
Gold mines often have other types of mineral components, such as iron ore, lead ore, antimony ore, etc. Among them, the metal component will have a certain effect on cyanide leaching, slow down or accelerate the dissolution of gold. If the gold ore contains carbonaceous materials, it will affect the reaction of the ore particles wrapped with carbon materials with the cyanide solution, hindering the dissolution of gold. Moreover, the activated carbon in the ore will adsorb the dissolved gold, resulting in gold robbing, thereby reducing the gold leaching rate and recovery rate, and having a serious impact on the gold extraction process.
In order to mitigate and eliminate the harmful effects of other mineral components on gold extraction by heap leaching, the heap should be fully sprayed and washed with saturated alkaline solution before cyanide leaching to precipitate other harmful mineral components, Decompose to keep the PH value of the solution discharged from the mine heap above 9.54, and discard the washing water and then use the heap leaching method to extract gold.
Generally, the smaller the ore particle size, the shorter the leaching time and the higher the leaching rate. However, in actual situations, the ore particles that have been crushed to 5-20 mm are heap leached. If the content of powder ore exceeds 35%, the conventional heap leaching method will cause the surface of the heap pile to form a channel and reduce the gold leaching rate.
2. The influence of leaching solution
Using low-concentration cyanide solution, such as the concentration of cyanide solution is below 0.05%, the gold dissolution rate is fast; using high-concentration cyanide solution, such as cyanide solution above 0.15%, the gold dissolution rate is slow. Therefore, according to the ore composition and different leaching stages, it is more appropriate to control the concentration of the cyanide solution between 0.025% and 0.1%.
The dissolution rate of gold is proportional to the concentration of oxygen in the solution. A decrease in the concentration of oxygen will inevitably lead to a decrease in the rate of dissolution of gold. Therefore, the leachate should be ventilated and oxygenated to ensure that the participating oxygen is always sufficient.
3. The influence of spraying
When the spray intensity is large, the relative movement between the solution and the ore is strengthened, the diffusion is strengthened, and the leaching rate is improved. However, the spray intensity should not be too large, otherwise the impurities in the mineral will be leached and the gold content in the leaching solution will be reduced. Generally speaking, the spray intensity is controlled at 0.05 ~ 0.1L / t per minute.
4. The impact of heap leaching
The pile has good permeability, and the gold-containing solution can be discharged through the pile in time, speeding up the leaching reaction speed, shortening the cycle and improving the leaching rate. Factors such as the size of the leached ore particles and the clay content in the ore will affect the permeability of the ore pile.
Oil with good permeability can be set higher in the pile height. For ores with poor permeability, the height of the pile should not be too high, otherwise it will reduce the permeability of the pile and extend the leaching time. Generally speaking, it is appropriate to keep the height of the mine pile at 3 ~ 10 meters. The height of the pile can be determined through experiments.
Although the process of gold extraction by the heap leaching method is short and effective, it is affected by many factors in the gold extraction process. In order to ensure the smooth progress of the withdrawal, it is necessary to comprehensively consider various influencing factors and take effective measures to analyze, study and control.
