Oxygen solubility in ammoniacal solutions of the type used for pressure lea
ching of sulphide concentrates has been modelled as a function of oxygen pa
rtial pressure, temperature and the conjoint presence of several inorganic
solutes. This was achieved by combining oxygen solubility models for pure w
ater and single solute solutions with published experimental data for singl
e solutes of relevance to sulphide leaching. Differences between the oxygen
solubility effects of dissolved molecular ammonia and ammonium salts were
noted and analysed. Justification was made for assuming no distinction betw
een effects of ammine cations and normal aqueous (solvated) cations on oxyg
en solubility. Applications of the model to industrial solutions are discus
sed, including estimation of oxygen concentrations and optimum process temp
eratures for mass transport of dissolved oxygen. (C) 2000 published by Else
vier Science Ltd. All rights reserved.