Solutions to improve production and energy efficiency at minerals enrichment plants

Presentation reviews how controls based on real time and representative measurements that monitor the product, so the solids and their particle sizes and propagation in the process can significantly improve the production efficiencies at concentrators. Customer case-based comparisons to conventional technology solutions are presented and the reasons for improvements are highlighted.
Further we introduce the new separation technology P29, which is an evolution in minerals processing technology.
The first grinding stages and combined classification to create optimal particle sizes for following process stages is the process area that is critical both for the plant throughput and recovery. Improvements are gained by direct, representative real time particle size measurements from the overflows of every hydrocyclone. Conventional solution has been to take small samples of the battery consolidated flow and assume all cyclones work similarly. Combined with that they typically also monitor the operational stability of cyclones trying to detect exceptional operational situations. The direct particle size measurement has clearly revealed that cyclones in the batteries do not work similarly, and each cyclone also affects the operation of other cyclones, especially the nearest ones. Up to 10% increases in net metal production have been gained with grinding controls based on direct and representative real time particle size measurements.
Another improvement area is the monitoring of production rates between process stages and to define process mass balances. Conventional technology has been to measure the flow with magnetic flow meters. Those basically measure the flow of the carrier water (measuring ion flux through a specially shaped magnetic field and assuming ions are evenly distributed in the pipe). Customers produce minerals, not water, so basing controls on water flow is not the optimal solution. Due to gravity and mass inertia the solids in process pipes are never evenly distributed, which causes errors for magnetic flow measurements leading to process disturbances and line blockages, so losses of production time and production efficiency. Additional drifts and production time losses are caused by variations of air content in the lines and the wear of the contacting magnetic flow meter electrodes. The passive SONAR clamp-on and totally maintenance free technology measures the propagation rate of turbulences that carry the solids forward in the lines, providing non-drifting and reliable information for the key process stage controls and mass balances over the process lifetime. Further it provides real time information on the flow model (used to detect process disturbances for blockage prevention) and measures the volumes occupied by air/gas bubbles in the flow (used to correct the errors those cause for density measurements and rapidly and correctly react to process disturbances caused by high air contents).
The P29 mineral separation technology utilizes common industry standard equipment along with a proprietary engineered hydrophobic coating on industrial reticulated polyurethane foam that replaces the functions of air/water bubbles in froth flotation. A biodegradable non-ionic surfactant is used as a mineral release agent to release the mineral from the collection media. Both the collection media and release agent are then reused in the P29 process. P29 can recover large poorly liberated mineral particles with little to no free gangue entrainment, up to 2-3 mm. When compared to the 0.2 mm reachable by flotation, this means significant savings in grinding energy per ton produced. In brownfield operations the existing flotation process can be optimized for fine particle recovery while coarse particle recovery is done through the P29 process. This can increase the throughput of the existing grinding circuit by 20 - 40% without costly investments in new grinding circuits. As P29 provides also a coarse rougher tail the water recovery will be significantly enhanced, and the P29 coarse rougher tails enable more stable tailings dam constructions.
For greenfield projects P29 offers lower investment and operational cost production process as conventional grinding can be replaced by one or two HPGR stages after crushing to feed the P29 process. Significant savings in investment and especially in the operational costs over the production plant life time.