As populations increase, so does the need for resources, including metals such as nickel, silver, gold, copper, and uranium. However, it is not always economically viable to extract these metals from their low-grade ores. And now more than ever, recovering them from what is available to us, is of the utmost importance.
What is Heap Leaching
Heap leaching is a process through which metals are extracted from the ore in which they are found. Heap leaching is often chosen for its efficiency and cost-effectiveness. As the need for resources increase, the heap leaching industry has risen to the occasion with advancements creating an even more efficient leach. One of which, is the process of agglomerating the ore prior to the leach.
How Heap Leaching Works
As seen in the flow chart below (figure 1), the ore, after being removed from the ground, is crushed down into fine particles. Traditionally, the fine particles would typically go from crushing straight to a heap, where leaching solution would be applied, and the metal would leach out. While this method is effective, its efficiency has been highly increased by the addition of a rotary ore agglomerator after crushing.
Research has shown that it is best to apply agglomeration technology to finely divided metal-bearing feed materials. Agglomeration of the fines allows for enhanced, and even percolation of a heap. If left un-agglomerated, smaller fines can accumulate in the interstitial areas of larger particles, inhibiting flow of the leaching solution (see figure 2).
In addition to better percolation, adding a rotary drum agglomerator to the heap leach process also provides further leach effectiveness through the addition of the leaching solution in the rotary drum prior to the heap. This agglomeration pre-treatment homogeneously blends the binders and leaching solution with the ore, further increasing leach efficiency.
Pre-treating ore fines by the process of agglomeration not only creates a more efficient leach, but it also de-dusts and improves bulk density to increase strength, allowing for larger heap piles and reduced crushing. Moreover, it also creates a more porous material to increase flow rate and metal recovery, reducing leaching time and residual leach solution in the heap.
Adding a rotary agglomerator to the heap leach process is a dependable approach in getting the most out of a heap leach.
FEECO has been custom engineering rotary agglomerators for over 60 years. For more information on our rotary drums, contact us today!