Coarser grinding and coarse particle recovery are receiving increased attention as a potential strategy for overcoming the multiple challenges that face the mining industry now and into the foreseeable future. Lower grade -normally harder- ores require the processing of larger ore quantities to achieve even the same production rate; necessarily increasing production costs. As dictated by the well known comminution laws, coarsening the final ground product size significantly increases throughput and reduces specific energy consumption and production cost. However, implementation of this coarser grinding strategy could be hindered by two key limitations.The first limitation is adequately controlling the final product size to enable more closely approaching process barriers in a safe manner. This requires an advanced process control system that can achieve the desired target size with low size variability. Lack of reliable online real-time particle size measurement has been a key limiting factor to achieving this goal. A new measurement technology developed by CiDRA overcomes this, making the grinding circuit better suited to implement a coarser grinding strategy. The second limitation is the potentially lower metal recovery in conventional froth flotation due to its limited ability to recover coarse particles. Although studies show that this recovery loss is often more than compensated for by increased throughput, operations have traditionally been averse to accept recovery loss. Along these lines, CiDRA is in the final stages of development of a radically innovative “bubble-less” separation technology -therefore very distinct from conventional flotation- with the capability of recovering particles across the entire size distribution, as produced by a grinding circuit operating in a “coarse grind” mode. This paper primarily addresses the first limitation. It presents a methodology for estimating the benefits of coarser grinding by using advanced process control enabled by a reliable online particle size measurement. Case studies and high-level control strategy are presented.
展开▼
