Orway Mineral Consultants (OMC) is a Perth and Toronto based metallurgical consultancy established in 1983, with a reputation for the delivery of high quality studies and practical engineered solutions in the areas of comminution, beneficiation and hydrometallurgy. OMC optimise and audit comminution circuits worldwide with involvement in over three thousand (3,000) different projects including four hundred (400) surveys across more than one hundred (100) separate optimisation projects.
Optimisation is a critical process for maximising the profitability of all metallurgical facilities within the constraints of the project. As Figure 1 shows, comminution is generally the most power intensive process and generally consumes in excess of 50% of total site power. In the US mining industry, 40% of all energy consumption is estimated to be attributed to grinding, inclusive of mining (drilling, blasting, hauling) and processing . Grinding power alone can account for around 20% of direct operating costs in a typical gold plant, inclusive of salaries, wages, fuel, reagents, wear parts, and maintenance . These percentages can be higher for ore types requiring high power input during comminution.
The impact of comminution on project economics is also increasing with the observed quantum shift in the minerals industry to low grade disseminated ore reserves. OMC work closely with their clients to set optimisation goals; not only tonnage and grind size but improved project economics and or cash flow. The priority of these two aspects is not always the same and this difference is often not well understood by operators focussed on the process plant. Although optimisation is project specific, cash flow for the existing asset is typically targeted first, particularly in tough financial times, and project economics are targeted second, as the latter is often more capital intensive. Optimising the throughput of the grinding circuit can have economic benefits well beyond the processing plant allowing optimisation of key project features such as cut off grade in mining which significantly alters project economics.