Modern Mining December 2018

MINING News

Advanced milling control system installed at Asanko

The performance of the Asanko processing plant (seen here) has been enhanced by the use of an advanced milling control system.

DRA Global recently implemented a state-of-the-art advanced milling control system, using the MillSlicer instrument, at the Asanko Gold Mine (AGM) in Ghana. AGM is a large scale, multi-pit asset located on the Asankrangwa belt. Built in 2015 by DRA Global, ahead of schedule and within budget, first gold was poured in January 2016 and commercial production com- menced in April 2016. Operations at Asanko prioritise efficien- cies, with minimal downtime. Unplanned or forced mill stoppages and breakdowns

trol systems, specific to an operation,” says Val Coetzee, DRA’s Senior Vice President Process. “The program allows for accurate mill charge toe-angle measurement and real time polar plot determination, which is used in the customised control system.” The milling control system, which was commissioned by DRA in August 2018, uses proprietary ‘rule-based algorithms’ which assist the mine’s operation with superior control, maximising energy effi- ciency and ensuring continual optimal mill performance despite any changes in mine fragmentation or ore type variances. “DRA is able to provide remote opera- tional support, data analysis and reporting to assist clients in reducing liner damage, media consumption and ensure that mill operators efficiently maximise throughput at all times,” states Coetzee. “This MillSlicer hardware and the DRA advanced control system, in conjunction with a number of other initiatives relating to open circuit modifications, use of cam- eras and feed blending, have successfully contributed to the performance excellence of the Asanko processing plant in recent months.” Russell Bradford, SVP Metallurgy at Asanko, comments: “The MillSlicer hard- ware has enabled the Asanko team to optimise the mill’s performance by ensur- ing we always have the right blend of ore at the right tonnages in the mill. Since this technology was implemented, the Asanko processing plant has consistently delivered above its 5 Mt/a design rate.” 

can often lead to costly setbacks for overall mine operations. The DRA Global technical processing specialists collaborated closely with the Asanko owner’s team to develop a control system solution that is able to produce real time reporting and enable the mill operators to better optimise the milling process. “This MillSlicer Control instrument provides accurate signals via a number of strategically positioned vibration sensors that are used by DRA’s comminution and control specialists to develop bespoke con- “The sale of our interest in Rössing once again demonstrates our commitment to strengthening our portfolio and focusing on our core assets, which deliver sector-leading returns in the short, medium and long term,” said Rio Tinto Chief Executive J-S Jacques. “Rio Tinto has a long history in Namibia and I would like to thank the many people across Rio Tinto and the communities in which we operate who have contributed to the success of Rössing. I wish them con- tinued success under new ownership. Rio Tinto will work closely with CNUC to ensure a smooth transition and ongoing sustain- able operation at Rössing.” Operating since 1976, theRössingbusiness has reportedly produced more uranium than any other single mine globally. It produces and exports uranium oxide from Namibia to nuclear power utilities around the world. In 2017, the mine produced 4,65 Mlb (approxi- mately 2 110 tonnes) of uranium oxide. 

Rio Tinto to sell its interest in Rössing Uranium Rio Tinto has entered into a binding agreement with China National Uranium Corporation Limited (CNUC) for the sale of its entire 68,62 % stake in Rössing Uranium Limited, the owner of the Rössing mine in Namibia, for up to US$106,5 million.

The total consideration comprises an ini- tial cash payment of US$6,5 million, payable at completion, and a contingent payment of up to US$100 million following completion. The contingent payment is linked to ura- nium spot prices and Rössing’s net income during the next seven calendar years. In addition, Rio Tinto will receive a cash pay- ment if CNUC sells the Zelda 20 mineral deposit during a restricted period following completion. The total consideration is sub- ject to a maximum cap of US$106,5 million. The transaction reportedly represents the culmination of an extensive assessment of strategic options considered by Rio Tinto in relation to Rössing.

4  MODERN MINING  December 2018