Every mine strives to achieve the highest possible throughput using existing equipment whilst also maximising the profit. SRK consultants have been engaged in increasing gold processing plant throughput with minimal capital investment.
Assessment of the operating parameters for crushing and grinding sections at selected plants allowed for improvements that increased throughput by 4−12%, which significantly improved the revenue of the operations. Key processes in each project were also monitored to avoid metal losses with plant tailings.
SRK’s approach includes the following steps:
- Reviewing performance statistics and identification of dependencies.
- Analysing mineralogical data, deposit characteristics and determination of the influence of variability of physical and mechanical properties on plant performance.
- Collecting samples of the plant feed for strength testing.
- Auditing the process flow sheet and collection of process samples.
- Estimating the capacity for each piece of equipment in the process line and comparison of estimated and actual performance.
- Process modelling using specialist software.
- Developing different upgrade options and estimating of potential throughput.
- Estimating capital investment and expected return from proposed modifications.
The solution to increase the plant’s throughput often lies on the surface. It may be the mill liner design, crushing size, solid-to-liquid ratio in the mill feed, ball load, unstable thickener performance, etc. If good quality and accurate raw data are available, the required estimates and changes in the plant process parameters can be completed relatively quickly, providing benefits without significant capital investment.
The importance of exploring plant feed hardness variability as part of geometallurgical mapping deserves special recognition, as it is a powerful tool for ensuring the reliability of planned production and financial performance. Different methods are used for hardness determination; mines often use a simple bench-scale grinding test using a laboratory mill with preset time and controlled product size. Each method has its own benefits and drawbacks. SRK helps to optimise the cost of geometallurgical mapping programmes while collecting relevant information.
In one case study, the mandate was to increase throughput at one of the operations with minimal capital investment. Following an audit and assessment of the equipment condition, the maximum theoretical equipment capacity was estimated, taking plant feed strength properties into account, and a plan to increase throughput by 13% was developed. The project was implemented successfully: with less than US$1.2M invested, the plant’s throughput increased from 1.69 to 1.9 Mtpa.
