Effective Methods of Arsenic Removal from Gold Mine Wastes

"The basic problem of arsenic contamination from mine water is discussed. Effective methods of removal involving chemical precipitation, activated carbon adsorption, ion exchange and reverse osmosis are discussed. As well as an economic analysis, detail is also paid to other ions in solution which are removed simultaneously.INTRODUCTIONThe object of this paper is to review arsenic and its removal from gold extraction plant effluents. The first method considered is chemical precipitation. A second method is sorption processes, such as ion exchange resins and activated carbon adsorption. A third method is the possible application of reverse osmosis for the treatment of mine waste waters containing arsenic.Arsenic pollution in the gold mining communities of Canada and Ghana have been extensively studies (l, 2). Lynch(3) Shabunin, Gutman and Kogan( 4), Hollo, Troth, Vennes and Illinigi (5) and Hau(6) have reported their removal methods of arsenic by chemical precipitation, ion exchange and biological methods. Their conclusions were that the precipitation with Fe2+ and Fe3+ ions was most effective.Scope of the ProblemInitial aspects of this research program involved a detailed analysis of the operation of a gold extraction plant located in Canada. The name and location of the mine is proprietary information. Figure 1 gives a basic process schematic with the main tailing streams identified.Table 1 gives information as to the various mine streams and their physical and chemical composition. In this study, primary attention is paid to the removal of dissolved arsenic from waste waters. Solids from this type of operation can always be back-filled. As could be anticipated, the dissolved As content of the primary flotation tailing stream is very low. The dissolved As level in the secondary processing stream and the roasting quench water is quite high. The reason being that at this stage of the process, the arsenic has been freed from the arsenopyrite forms."