Leaching behaviour of a chromium smelter waste heap

This paper reports the results of geochemical sampling and modelling of Il: achates from a chromite ore processing residue (C.O.P.R.) pile under rainwa ter infiltration. The waste pile is located in the north of England and con sists of 800,000 m(3) of waste. The pH of fresh leachate is similar to that of a solution in equilibrium with portlandite Ca(OH)(2), which is a major constituent of the waste. The in-gassing of CO2(g) causes the pH of the lea chates to drop along the drainage ditch and calcite precipitation to occur. The extent of in-gassing is dependent upon the flow rate within the draina ge ditch. The dissolution of solid solutions containing residual chromate i s likely to control chromate concentrations within the leachate. (C) 2001 E lsevier Science Ltd. All rights reserved.