Arseno/redox process for refractory gold ores

ABSTRACT Arseno Processing Ltd. has been developing a nitric acid based process for treating refractory gold ores and concentrates since 1981. The technology is being marketed as the Redox Process. With the participation of Minproc Engineers, the process has been operated on a continuous pilot scale with both a low sulphide whole ore and a high sulphide arsenopyrite concentrate. The conditions used for these drastically different feeds are also very different. For the arsenical concentrate the process conditions which were used resulted in no elemental sulphur formation so that subsequent cyanidation could be performed efficiently and economically. Feasibility studies have been completed for both properties which were piloted. Favourable economics were demonstrated in each case and these projects are expected to proceed to commercial production during 1989. This paper reviews the conditions used for these feeds and discusses the results achieved, together with the projected economics. The potential for application of the technology to more complex feeds is also discussed.