February 2014
MODERN MINING
13
MINING News
Efficiency enhancement projects at the Tongon gold mine in Côte d’
Ivoire have boosted its performance significantly, and the planned
expansion of the flotation process should lift the recovery rate to
its feasibility study level, Randgold Resources Chief Executive Mark
Bristow said recently. He was speaking at a quarterly media briefing
coinciding with a mine visit by international investors.
Bristow said that while Tongon had increased production, its recov-
ery rate, while slowly improving, was still struggling to break 80 % for
the year. An additional 2 % was achievable by optimising the existing
recovery circuit, but raising the recovery rate to the targeted upper
80s will require an expansion of the flotation process to capture most
of the sulphide in the ore. Initial estimates of the cost to expand the
float circuit amount to US$12 million. It is targeted for completion by
the end of 2014 with a forecast payback period of eight to tenmonths.
“The standard CIL circuit is not recovering that portion of the gold
associated with arsenopyrite which is bypassing the existing flash flo-
tation cells. The original metallurgical testwork indicated that the bulk
of the Tongon ore was amenable to cyanidation, with flash flotation
in the mill circuit recovering the gold associated with the sulphides.
In practice, however, we’ve seen that this process is not recovering
enough of the fine gold associated with arsenopyrite. The expansion
of the flotation circuit will address this issue by capturing the full
spectrum of sulphides,” he said.
In the meantime, Tongon is forecasting production of approxi-
mately 260 000 ounces for 2014, which is an increase on 2013’s gold
output but slightly behind the internal target.
“It has been another challenging year for Tongon but its manage-
ment has coped admirably with the operational challenges as well
as with the need to adjust to the lower gold price. The continued
optimisation of the grid power is delivering cost savings, three of
the four new Vibracone crushers have been commissioned and the
Ivorianisation of the team is making good progress,” Bristow said.
Flotation expansion project
planned for Tongon
Drill-for-equity agreement
North River Resources has announced a drill-for-equity agreement
with the owner of the drilling and mining contractor operating at the
company’s flagship Namib lead-zinc project in Namibia. Under the
terms of this agreement, which also establishes an important local
partnership for North River, Wilhelm Shali will be paid in shares of
North River rather than cash for drilling programmes.
The agreement has initially been established to cover the first
£175 000 worth of invoicing for drilling activities.
The company is drilling on double shift in the historic underground
mine to quickly expand its resources, which currently stand at 917 000
tonnes at 2,4 % lead, 5,7 % zinc and 44,8 g/t silver. As part of this pro-
gramme, work is about to commence on driving a 300 m exploration
tunnel to create new drill pad positions under the Northern lodes.
Martin French, North River’s Managing Director, commented: “We
are very pleased to be announcing today an investment from our
local drilling partner. We have been working with Shali Mining for
four months now at Namib and the decision to invest sends a strong
signal to the market on the project’s potential.”
