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.