Extraction of gold from sands and slimes tailings dump from Mazowe mine, Zimbabwe

Abstract

The Mazowe Gold Mine is managed by Metallon Gold (Zimbabwe) and is situated in the west-central part of the Harare greenstone belt. Orebodies here generally comprise shear zones which are in-filled with gold-bearing sulphides and quartz. The mineralised zones are up to 1 m in width, have average grades of 4–5 g/t. Mazowe Mine is one of the oldest mines in Zimbabwe, and exploration and development in this region dates back to 1890, with over 1.4 million ounces of gold produced to date. Ore is processed in a single plant which consists of conventional crushing and milling and carbon-in-leach facility. Baldmin Projects was awarded the contract for the design, construction and commissioning of the 60,000 tonnes per month plant at Mazowe mine in 2014 for the processing of old tailings dump from previous operations at Mazowe mine. The average grade of the tailings is 1.1 g/t. This paper describes the test work, process design of a processing system at the Mazowe Mine that will improve the extraction efficiency from gold tailings material. The recovery is derived from the separation of the gold contained within the sulphides of the tailings material and a dedicated process stream to recover that gold. The sulphides are separated by means of flotation process and that resulting concentrate is subjected to regrind below 25 µm to enable a greater liberation of the gold. The fine material is then subjected to a dedicated leach process to recover the now exposed gold particles. The case study is an example of the challenges of using existing technology and methodology to a well-established process and there by attaining improved efficiencies and tangibles business benefits.