Xstrata Process Support (XPS) notes that “deeper mines, lower grades, and higher processing cost all place pressure on mining operations. In order to remain profitable, today’s mining companies need to mine smarter, not harder.” One underused opportunity for smart mining lies in the concept of preconcentration” of ore. Modern process developments have produced rapid advances in sorting technologies. In spite of numerous successful installations in other countries, such as South Africa and Australia, these have largely not been used in Canadian mining operations.
Preconcentration is the term applied to any beneficiation process which takes place between mining and final milling of the ore. Preconcentration techniques can be applied to relatively coarse ore and use some measurable differences between valuable ore and barren waste rock. It could equally and as accurately be described as “waste rejection”. The available techniques include measurements of optical, density, X-ray, and conductivity differences. The many benefits of pre-concentration include:
- Improved availablility of back-fill material
- Reduced economic cutoff grades
- Improved concentrate grade
- Reduced smelting losses
- Reduced energy consumption
- Reduced size of tailing dams
- Reduced material handling
- Lower transport cost
- Improved life of mine.
XPS, MineSense Technologies and CEMI (the Centre for Mining Excellence) have collaborated on a project to raise awareness of the potential benefits of implementing preconcentration of ore. This collaborative effort has culminated in an executable model aptly named PreCalculatOre. This tool is available as a free download from the CEMI website (www.miningexcellence.ca). CEMI hosted a short course on the topic on April 27.
PreCalculatOre is a combined process and cost model for the rapid assessment of the mineral economics for applying preconcentration at a mine versus a base case with no preconcentration. The process model is founded on proprietary mass/metal balances for mineral processing, smelting and refining steps developed by XPS, and coupled with proprietary capacity/cost models developed by MineSense to estimate the impacts on metal recovery and process costs for the base and preconcentration scenarios.
Once the advantages of preconcentration are shown by the model, the next step is to submit a representative sample of ore to XPS for preliminary evaluation of the amenability of the ore to any one of many available preconcentration techniques, and a recommendation as to which technique would be most suitable. XPS will then assist the client in arranging a pilot test campaign of the ore. Over the past few years XPS has evaluated numerous ores, and in most cases, suitable preconcentration technologies have been identified adding significant additional value to client resources.