On the pre-layed bottom pad, the ore pile that is out of the cage or the broken ore or the granulated agglomerate is called the heap to be leached, referred to as the immersion heap. There are many parameters that characterize the immersion heap, mainly:
First, the geometry of the immersion heap
The pile height depends on the permeability of the ore, the consumption rate and total amount of the leaching agent and oxygen in the immersion pile, the unloading height of the selected planting equipment, and the like, and the pile height is generally determined according to the specific object. According to the survey in the United States, 20% of the pile height is 0.9 to 1.8 m, and 30% of the pile height is 2.1 to 3.6 m. It is obvious that the former uses rear unloading cars to build piles, and the latter mostly uses front-end loaders to pile up. The height of the immersion pile using the transport belt and the curved piler is generally 6 to 18 m. The domestic immersion height is generally 2 to 3 m, but tends to be 5 to 7 m.
The volume of the immersion heap refers to the total volume of a single pile, not the total volume or annual throughput of several tandem leaps in a mine. Heap leaching heap which mainly depends on the volume of the terrain, the leaching rate, the size of the subsequent treatment process and other artificial arrangements (such as revolving funds, schedule, etc.), it did not rely on high-pile strong objectivity, but There are more artificial factors. Therefore the volume of the immersion heap has not been standardized. According to the survey, in the 88 gold mine leaching sites in the United States, the volume of the leaching pile (expressed in the amount of single ore) is 50% below 50,000 tons, 17% is 50,000-100,000 tons, and another 17% is greater than 30. Ten thousand tons, individual raw ore piles reached 2 million tons, and even hundreds of millions of tons.
Second, the permeability of the heap
The main indicator of the quality of osmotic immersion reactor, it includes two aspects: one is the size of the permeation rate; the other is the uniformity of the penetration of each part of the leaching pile. Generally speaking, the permeability of the immersion pile should meet the requirements of the maximum spray strength, so as not to cause the surface area of ​​the heap. But this is not enough. Considering the stability of the pile slope, the permeability of the pile must be adapted to the maximum rainfall requirements. In general, the permeation speed of the immersion reactor is required to be greater than 50 L/(h·m 2 ).
In addition to the permeation rate of the heap, the permeability of the leach also emphasizes the uniformity of penetration of the various parts of the leach. It is unrealistic to require the penetration speed of any tiny area of ​​the dip pile to be completely uniform, but the uniformity coefficient should not be higher than 20%, otherwise serious channel flow will occur.
Third, the stability of the heap
The stability of the immersion heap also includes two aspects: First, the limit of the pile height (especially for the permanent yard, after the first layer leaching, the new pile is built up layer by layer) and the relationship with the foundation, never allowed The vertical pressure caused by the weight of the ore in the immersion pile causes the foundation to collapse; the second is that the slope of the immersion pile is always not landslide. This depends on the size of the dip angle of the dip, and should also take into account the spray intensity, especially the scouring caused by heavy rain. The larger the angle of repose of the immersion pile, the smaller its stability; the higher the pile, the worse the stability; the coarser the particle size of the ore, the smaller the stability of the immersion pile; the better the permeability of the immersion pile, the steeper slope The greater the stability. A poorly permeable immersion pile often has water on the surface. Once heavy rain comes, a large amount of water rushes to the surrounding area, which often causes landslides.
The ore of different grain sizes is piled up and has its natural rest angle. The natural rest angle of the ore of -40mm in different shapes (except for the spherical shape) is between 380 ° and 42 °. For the stability of the dip slope, the angle of repose of the immersion pile must be smaller than the natural repose angle of the ore. As for the extent to which it should be small, it should be determined according to factors such as pile height, permeability, and heavy rainfall.
In granulation heap leaching, within 1 to 2 days of the start of spraying, the natural immersion of the immersion pile is a natural phenomenon, which usually does not endanger the stability of the pile. In the case of heavy rain, as the granulation increases the permeability of the immersion pile, once the rainstorm stops, the accumulated water will soon be emptied.
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