There are four common gold ore beneficiation methods, including flotation, heap leaching, CIL carbon leaching and CIP carbon pulp. In the selection of beneficiation methods, the mineral composition and properties of the ore should be analyzed according to the beneficiation test, and the results should be determined after repeated tests. We have previously compared the effects of gold flotation and cyanide gold extraction. Today, we will compare gold heap leaching with flotation from three aspects.
The application field of flotation is very wide. It is suitable for rock gold ore, especially sulfide mineral gold ore with high floatability. More than 80% of gold mines in my country use flotation. This is because the flotation process has low cost, but the gold extraction effect is significant. It can enrich gold to a large extent in sulfide minerals for gold extraction operations. The gold content in the tailings will be correspondingly reduced, and the tailings do not need to be re-processed and can be directly discarded. After years of practice, the gold flotation method has become very mature, and the effect of improving the concentrate grade and recovery rate is also obvious.
The application field of heap leaching is relatively limited, because it is only suitable for some gold mines with low grade, small ore bodies, and cannot be processed by conventional methods. For high-grade and large-scale concentrators, it is impossible to complete gold extraction by heap leaching alone, but to use it as an auxiliary means and cooperate with other processes to complete the operation, so as to better improve the concentrate grade and mineral processing recovery rate.
The general process of gold flotation is one-stage grinding (two-stage or multi-stage grinding)-flotation process. For ores with uneven particle size, stage grinding and flotation process can be used. The parameters such as grinding fineness and pulp concentration should be controlled in the grinding stage. The type of flotation reagent, the amount of aeration and the flotation time should be paid attention to in the flotation stage. Only by controlling these parameters can the ideal flotation effect be achieved.
The general process of gold heap leaching is to crush the low-grade gold ore to a certain particle size (or granulate), pile it on a leak-proof bottom pad paved with materials such as asphalt, concrete or plastic, spray it on the ore heap with low-concentration cyanide, alkaline solution, non-toxic solvent or dilute sulfuric acid solution to dissolve the gold, and the gold-containing solution is filtered out from the ore heap, and then the gold is recovered by activated carbon adsorption or zinc powder replacement precipitation.
By comparison, it can be seen that no matter which method is used to extract gold, the previous crushing and grinding stages are indispensable. Only by grinding the ore into smaller particles can the process of dissociation of gold from other gangue mineral monomers be completed.
In terms of required equipment, the difference between gold heap leaching method and flotation method is also relatively large. The equipment required for flotation method includes crushing and grinding equipment. In the selection stage, reagent mixing tanks and flotation machines are used. In the dehydration stage, filters, thickeners, dryers, etc. are needed. Auxiliary equipment such as conveyors, slurry pumps, and hydrocyclones are also indispensable.
The equipment for gold extraction by heap leaching is more special. In addition to conventional crushing, grinding and grading equipment, leaching mixing tanks, desorption electrolysis systems or zinc powder replacement systems are also used.
In general, flotation method is suitable for most gold ore selection, while heap leaching method has a narrow scope of application. Only a small number of gold mines are suitable for heap leaching method. The process flow and required equipment of the two are also quite different. Regardless of which method is used, the final concentrate grade and mineral processing recovery rate are our goals. As long as these two items meet expectations, it is a suitable gold ore beneficiation method.
