Despite the recognized significance of ground product fineness on both line capacity and downstream process performance (typically flotation), less than 10% of mineral ore concentrators today use real-time particle size measurements in automatic control applications for the final product particle size. Although “near-line” particle size measurement instrumentation has been in place for several decades and is commonly installed in most modern concentrators, its availability and low measurement frequency have typically been inadequate for reliable use in automatic control. Their low availability is often associated with problems with slurry sample collection and handling systems required to present the samples to the size measurement instrument. Recently, an innovative technology for real-time, on-line particle size measurement has been developed by CiDRA Minerals Processing, under its commercial name Particle Size Tracking (PST), already proven in several commercial installations, demonstrating near 100% availability with minimal maintenance, thus overcoming the limitations of previous technologies. Investment decision makers require convincing, reliable estimates of the expected economic value that automatic grind control projects will deliver. This paper presents a methodology for estimating such value from the installation of the new PST particle size measurement technology, capable of tracking particle size on each individual hydrocyclone overflow stream, thus adding significant new options for improved process stability and performance. Based on actual plant operating records, accumulated over long periods of time, the evaluation approach herein described assesses and highlights the significant potential contribution to be expected from this unique PST technology.
This paper presents a new instrument for real-time detection of excessively coarse material in the overflow pipes of individual hydrocyclones using a non-invasive acoustic measurement technique. The hydrocyclone is an important device used in mineral processing beneficiation circuits for classification of mineral slurries by particle size. It separates a single input stream into two output streams; an underflow of coarse particles that undergo additional grinding for further size reduction, and an overflow stream of finer particles that typically goes directly into a flotation circuit for recovery of the desired mineral. However the hydrocyclone is a major piece of equipment in the beneficiation process that has no instrumentation for directly measuring its performance. The parameters currently measured -inlet pressure, feed flow rate, feed flow density -are common to the entire hydrocyclone cluster which typically has three to twelve hydrocyclones. Thus no information is available to detect individual hydrocyclones that are operating poorly. The system described in this paper detects the presence of unwanted excessively coarse material in the overflow stream of a hydrocyclone using sensors mounted to the exterior pipe surface. It provides real-time monitoring, trending and alarming of the coarse material level. This enables operators to identify poorly performing hydrocyclones, and enables corrective action to reduce or eliminate the coarse material discharge. Improving the classification efficiency of individual hydrocyclones will improve the overall classification efficiency of a hydrocyclone cluster. This leads to less variation in the particle size distribution and slurry density in the flotation feed, which will in turn improve overall mineral recovery. The reduction of unwanted coarse material in the flotation feed reduces the accumulation of that material in flotation cells. This can lead to equipment damage, and unplanned shutdowns due to events such as blocked dart valves.
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