The coal quality procedures at Premier Coal are able to ensure that coal is supplied to the customer’s required specification. The stockpile system allows the quality of a consignment of coal, nearly 60,000 tonnes, to be accurately monitored over a period of three days whilst it is being produced. The reclaim system of this stockpile recovers the coal at 90 degrees to the direction in which the coal is layed down. This ensures that the quality of the coal recovered over the full stockpile is very consistent.
The coal in the mine plan has been well defined for quality and tonnage from drilling carried out ahead of mining. Based on this information, the quality control staff plan the mining sequence to ensure that the final stockpile is at the desired quality.
Whilst the coal is being crushed it passes over a continuous coal analyser that gives ‘real time’ results for the ash,moisture and sulphur content of the coal. This information is used to provide warning of any problems but is not used to determine the stockpile quality. The true stockpile quality is obtained from laboratory analysis of samples provided to a NATA-certified, independent laboratory. Incremental samples are taken automatically with approximately 50 individual cuts of the coal stream, to supply a composite sample, representative of approximately 2,500 tonnes of product coal. The laboratory provides a “rapid” sample analysis to the mine within two hours of delivery. The “standard” analysis is performed to the appropriate Australian Standard within 24 hours.
The laboratory has a direct computer link to the mine so that the analysis results are reported directly into the mine site coal quality management system (CQMS). The CQMS shows the quality of the stockpile as it is being built and allows remedial action to be carried out if necessary. As the coal is being added to the stockpile, the cumulative quality is being compared to the plan for the stockpile.
As a result of these procedures and the physical design of the stockpiling system, the mine has a reputation for excellent quality control.