Coal Preparation » Environmental Improvement
The objective of this project was to deliver a concise reference document which relates measured water quality to corrosion and scaling measurements, and flotation/dewatering performance measures. This was done by studying effects of water quality eight mine sites. Water quality for both raw make-up and clarified water were regularly monitored at each site. The project focussed on the following parameters:
- Water quality quantification and observation of variations;
- The impact of water recycling within each CPP upon clarified water quality;
- Corrosion propensity and corrosion rates (mild steel); and
- Process reagent demands in terms of flotation and dewatering.
Regarding measurement of corrosion rates, the basic methodology of study consisted of exposure of standard uncoated mild steel sample plates at varying positions at each site for 12 to 14 months of the project duration. Corrosion rates, assuming uniform corrosion, were assessed at each CPP via mass-loss determinations. These mass losses were converted to Corrosion Rate (CR, µm/year)) and have been correlated with exposure conditions and water quality.
No significant correlation with Corrosion Rate was observed for any single water quality parameter. However, a multivariate analysis identified a strong correlation (R2 = 0.829, Figure E1) when CR was expressed as a function of the average exposure qualities for each of three parameters:
The work undertaken in this project was a 'real world' exercise where all sites were different and outcomes would be heavily influenced by the different site conditions, particularly time of wetness. Results described in the final report show conclusions can be drawn between water quality (composition) and CHPP parameters.