Modern Mining

The new Mako gold mine of Toro Gold in eastern Senegal is off to a good start, with most metrics exceeding forecasts. Mill throughput for the first three months of operation, for example, was 540 kt at 2,34 g/t Au versus the budget of 460 kt at 2,49 g/t Au while average cash costs (including the ramp up phase) were US$746/oz versus the budget of US$984/oz, excluding royalties.

Construction of Mako, which is 90 %-owned by Toro, a Guernsey-registered private gold exploration and development company, started in August 2016 and the first gold pour took place on 26 January this year. Built within its budgeted capex of US$158 million, it will produce 136 koz/a of gold over six years of open-pit operation (although eight years of processing are planned). The ore is treated in a 1,8 Mt/a processing facility built by Lycopodium.

Mako Plant

The 1,8 Mt/a processing plant of the Mako gold mine (photo: Mako).

Highlights over the period January to April 2018 include a successful transition to steady-state operations at design levels of performance within a month of first gold pour; gold sales of 32 556 ounces at US$1 325/oz, slightly ahead of the 32 270 oz target; and metallurgical recoveries of 94,8 % against the forecast of 91,3 %.

Mining operations have been on-going since mid-2017 during the construction phase and have progressed well with good performance from the mining contractor African Mining Services Senegal SARL (AMSS), says Toro.

Given the topography of the deposit, the mining plan developed as part of the feasibility study anticipated very limited weathered/soft material to be mined with hard/fresh ore anticipated almost from the start of mining operations. During the development of the open pit, however, it became apparent that the weathering profile is more extensive than planned resulting in both the availability of free dig material and the use of lower powder factors for blasting – leading to improved operating costs through a reduction in drill and blast costs.

A strategic review of the pit sequencing and access layout is underway with the aim of optimising operational flexibility and reducing operating costs through shorter haulage distances. In the short term, there has been a focus on developing available ore benches over the first quarter with mining operations switching focus back to waste stripping during Q2 2018. To this end, ore tonnes mined are 10 % higher than budgeted over this period against waste production which is 18 % lower than forecast. This short term change has been implemented without impacting on the availability of mill feed during the balance of 2018 and beyond.

Commissioning and ramp up of the processing plant has been excellent, says Toro, with steady state production at nameplate levels experienced from within a month after the first gold pour. Accordingly, year-to-date milling is some 18 % above forecast as a result of both the rapid ramp up and mill availability of 95,4 % over the period against the forecast 94 %. Further, despite this increase in throughput, the plant is achieving its target grind size of P(80) 125 μm while using approximately 6,5 MW of power against the design of 8,4 MW.

General observations of wear points throughout the comminution circuit indicate better than forecast liner life which has led to lower operating costs and higher availability of the plant, reports Toro.

Further optimisation of the process plant will occur over the next six months to determine the optimal performance of the facility with target grind size, reagent use and throughput rates/power consumption reviewed with the aim of improving gold production and reducing costs.

Total employment at the mine during April, inclusive of all sub-contractors, was some 754 people. Training and skills development of the local Senegalese workforce remains a focus to ensure that the mine continues to provide the maximum long-term benefit to both the local and national economy of Senegal.

Comments Martin Horgan, Toro’s CEO: “After a highly successful construction period, the transition to operations has gone extremely well with all aspects of the mine operating either in line or better than forecast. Adrian de Freitas, General Manager, and the whole operations team have delivered an excellent first set of results and it has been achieved safely with no LTIs recorded for the period. I am also delighted to note that of the total workforce 88 % are Senegalese and over 60 % are employed from the local Kedougou region.”

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