Modern Mining February 2018

COPPER/SILVER

transmission in Botswana, that grid power will be extended along the Ghanzi Highway, 12 km from site, from 2020. MOD understands that contracts for the first stages of the transmis- sion line have been awarded and procurement is underway. All personnel will be based in the town of Ghanzi, approximately 80 km west of T3 along the sealed A3 Highway. MOD has begun con- struction of an accommodation village and operations base in Ghanzi. A 12 km graded road will run from the A3 to the site. The Expansion Case considers mining and processing at a rate of 2,5 Mt/a for the first three years as per the PFS Base Case. The process plant will be upgraded to be able to process at a rate of 4,0 Mt/a during the fourth year. Mining will be from a single, five-stage open pit with a waste to ore ratio of 4,28. The opti- mised pit was modelled as per the Base Case except for the inclusion of inferred mineral resources and the reduction in processing costs due to grid power. The T3 project will be able to commence operation as per the Base Case and can operate in this manner for two years without adversely affecting the option to imple- ment the Expansion Case. Processing is through the Base Case conven- tional SAG/ball mill and flotation circuit for the first three years. The process plant will then be upgraded – at an estimated capex of US$37 million – to process 4,0 Mt/a by the addition of a scats crushing circuit; rougher concentrate regrind mill; rougher flotation cells; concen- trate storage tank; and a concentrate filter. If the Expansion Case proceeds, the mine would have a life of 11,7 years from the start of production. Average life of mine produc- tion would be 28 kt/a of copper and 903 koz/a of silver. 

The process plant comprises a conventional SAG/ball mill and flotation circuit and will pro- cess run-of-mine (ROM) ore to produce a copper concentrate and tailings. The process consists of crushing and grinding of the ore followed by sequential rougher and cleaner flotation. Concentrate will be thickened, filtered and stockpiled prior to being loaded into 2 tonne bulk bags for storage and subsequent transport to third-party smelters. The flotation tailings will be dewatered by thickening and disposed of at the Tailings Storage Facility (TSF). Based upon core logging data, the copper mineral proportions across the deposit are esti- mated to be 60:30:10 for chalcopyrite, bornite, chalcocite respectively. On this basis and using metallurgical testwork data, recoveries are cal- culated to be 93,1% Cu and 86,2 % Ag. Flow testing of seven water boreholes has demonstrated the potential (subject to further testing) for a sustainable water supply to meet the needs of the process plant and related activities. Water analysis indicates that the water is low in Total Dissolved Solids; conse- quently, there will be no adverse effects on ore processing. Several options have been investigated in relation to the TSF and waste stockpile. The preferred option comprises a landform that integrates the TSF with the waste stockpile (Integrated Waste Landform). There is abundant gentle sloping room to allow for a significant increase in both tailings storage and waste stockpiling capacity. It is envisaged that the TSF would be lined with an HDPE membrane. Allowance is made for on-site diesel power generation with a total installed capacity of 14,1 MW. MOD has been advised by the Botswana Power Corporation (BPC), the util- ity responsible for grid power generation and

Proposed Base Case 2,5 Mt/a sulphide flotation plant.

The process plant comprises a conventional SAG/ball mill and flotation circuit and will process

run-of-mine (ROM) ore to

produce a copper concentrate and tailings.

February 2018  MODERN MINING  37