LABORATORY MODELLING OF DRAINAGE WATER COMPOSITION WHEN STORING GOLD CYANIDATION WASTES

Abstract

The article provides data on the composition of solutions obtained on the basis of experimental laboratory modelling of physical-chemical interaction in the ‘water-material’ waste dump system. Long-term storage of gold cyanidation cakes in the tailings of gold-processing factories can lead to the pollution of surface water bodies. This pollution is a result of active and passive interaction of atmospheric precipitation with the waste material. The solution in equilibrium with the leaching cakes has a pronounced alkaline reaction with pH value of > 9.0. During the first storage period the pH of the solutions increases as a result of hydrolysis reactions of excess reagent cyanides of alkali or alkaline-earth metals. Then the solutions pH is observed to decrease gradually towards the end of the first month of experimental observation. Sulphate ions, formed by the oxidation of metal sulphides in an alkaline medium, cyanide ions and heavy metal ions are accumulated in the solution due to the destruction of cyanide complexes with heavy metal ions, such as copper, zinc, cobalt, etc. The presence of arsenic in the drainage solutions in concentrations exceeding the maximum allowable concentration (MAC) is caused by oxidation of arsenopyrite contained in the source ore. Physical-chemical interactions result in exceeding of MACs for copper, cobalt, zinc, vanadium, chromium, molybdenum and wolframium in the drainage water established for fishery. Taking into account that the vast majority of water bodies in Kamchatka are spawning waters, it is recommended to treat drainage water using sorption methods. Local mineral aluminosilicate raw materials such as zeolites, which have an increased sorption capacity in neutral and slightly alkaline media, can be recommended to use as sorbents.