Modern Mining April 2018

COPPER

it was in the final stages of construction. “I had just left LionOre which operated the Tati Nickel mine near Francistown to form my own consultancy and was asked to undertake a feasibility study on the viability of installing a DMS at Mowana– which is something we had done at Tati with great success,” he explains. “The study – which was carried out in con- junction with SENET, who designed and built the Mowana plant – produced very positive results and its conclusions were accepted by the mine’s owners. But they were never able to implement the DMS project because the funds simply weren’t available.” Further confirmation of the viability of the DMS option has come from recent testwork undertaken by SGS Africa that has demon- strated that DMS pre-concentration can be deployed successfully at Mowana on all low oxide ores (defined as those containing less than 25 % acid soluble copper). According to the testwork, a mass yield of 30-40 % and a copper recovery of more than 85 % can be achieved. In addition, mill feed grades in excess of 2 % can be expected, nearly double the current ROM grade. Following the positive resource update and the metallurgical test results, Cradle Arc has prepared an Accelerated Development Plan (ADP) which is now in the process of being implemented. This will fast-track access to the deeper sulphide and supergene ores and allow Mowana to reach steady-state produc- tion and positive cash flows more rapidly. The goal is to reach the full 1,2 Mt/a capacity of the processing plant which will result in a yearly

reserve estimate and this will be published in Q2 2018. Van Wouw notes that while the Mowana plant was designed to handle oxide, interme- diate and sulphide ores, in practice recoveries on oxide ore were always poor – around 30 % compared to the 60 % predicted. “Our busi- ness plan is to treat the oxide material – much of which has already been ‘stripped out’ of the orebody – as waste,” he says. “We’ll stock- pile it and come back to it later. We know the supergene and sulphide ores recover perfectly in the float and this is what we’ll be concen- trating on.” Van Wouw’s belief in the value of upgrad- ing the front-end of the Mowana plant by

A Cat 374D excavator loads a Bell ADT at the Mowana copper mine.

Cradle Arc’s Mark Jones (left) and Kevin van Wouw, respectively COO and CEO.

putting in a DMS module dates back to his first encounter with the mine in 2007, when

24  MODERN MINING  April 2018