Energy Requirements for Comminution
Comminution is the process of reducing ore particle size for liberation of minerals in preparation for separation and extraction in downstream processes. It is a critical piece of almost all mineral processing circuits. Traditional comminution techniques such as SAG mill, ball mills, and rod mills fracture the ore by applying impact, compression, and shear forces using steel balls, rods, or other grinding media. These processes have very high energy consumption with very low efficiency. As a result, comminution consumes up to 4% of all global electricity and size reduction alone can account for up to 50% of an individual mine site’s energy consumption. Comminution energy and the resulting CO2 emissions have been high on the list of problems for the mining industry to address for many years.
Disa Technologies’ patented High Pressure Slurry Ablation (HPSA) Technology helps reduce overall energy consumption. The HPSA technology utilizes high-pressure slurry pumps to process solid feed material, in slurry form by pumping that slurry through a set of impinging nozzles, creating a high-energy, particle-to-particle collision zone contained in a collision housing. Through this unique and targeted application of energy, HPSA utilizes material as its intrinsic grinding media allowing for greater efficiencies as compared to those suffered by traditional grinding circuits which transfer much of their energy to the grinding media and not the processed ore itself. By improving the liberation in a single stage, HPSA can reduce overall processing energy by replacing the current grinding method, and also eliminating downstream regrind stages.
Figure 1: HPSA Batch Unit (Left) and CFD Image of Collision Region (right)
For many applications, the greatest liberation of valuable minerals from their gangue are usually seen at very fine particle sizes (sub 100 microns). As such, the mining industry is currently geared toward reducing the particle size as much as possible for these higher separation efficiencies. However, as particle size decreases, energy consumption to reduce the particle size even further increases exponentially. By liberating minerals along their intergranular boundary lines, HPSA can perform much more efficient liberation at particle sizes larger than the currently accepted industry standard. As a result of achieving this liberation at a larger overall particle size, HPSA has the potential to drastically reduce energy consumption and by extension GHG emissions of the minerals processing sector and the world. Due to HPSA’s unique ability to liberate composite material into its discrete subfractions along intergranular boundary lines, HPSA makes it easier to separate gangue material earlier in the processing sequence which reduces environmental risks and long-term liabilities.
Figure 2: Particle Size Vs. Energy Consumption Curve