Re-selection of ore is perhaps one of the most important steps in the production of minerals. It is also one of the most labour-intensive operations in the mineral processing industry. Re-selection of ore involves screening out rocks, minerals, and other materials, particularly tailings, from the ore that has already been mined and recovered. This re-separation process allows minerals to be separated from the waste and provides access to improved extraction capabilities.
The benefits of re-selection of ore can be deemed significant, particularly in the mining of complex ores. These complex ores often diminish the efficiency of a mining operation, as the concentration of minerals in such ores varies greatly between different samples. This is why re-selection of ore is critical when recovering minerals. By re-sorting and selecting the ore, higher-grade ore can be recovered from the waste material.
Re-selection of ore is completed in two major stages, namely the primary stage and the secondary stage. In the primary stage, much of the particle size distribution processing is done, where large particles are separated from the finer particles, and then the ore is scrubbed clean. This stage is completed in a device called a gyratory crusher, which exerts force on the rock in order to separate it from the other materials.
In the secondary stage of re-selection of ore, jigs and centrifugal concentrators are used. In the jigs, ore is first screened and then submerged in a tank where air bubbles are forced through the ore. The gravity concentrators then cause the ore particles to become suspended in the water, and these particles are separated based on their respective weights. In centrifugal concentrators, the ore is forced through a rotating cone. As it passes through the cone, the material of different densities is then separated.
After re-selection of ore has been completed, particles are divided into two categories, namely ore and waste. The ore is ready for the next stage of the process, typically comminution, where the ore is further crushed, ground and sifted until the desired minerals are separated and collected. The waste material typically goes through further re-selection processes in order to recover any of the valuable minerals contained within.
Re-selection of ore is a complex and labour-intensive process, but by diligently completing this process, improved extraction capabilities can be achieved. Recovery rates can increase significantly and improved ore grades can be achieved, resulting in the maximising of financial returns in the subsequent process stages. All in all, re-selection of ore plays a pivotal role in the production of minerals.
