Modern Mining January 2019

GOLD

A striking night shot of the mills at the Asanko processing plant. sensors – the SAG mill load position and toe angle and optimises the SAG mill power conditions. It prevents the mill from overloading, back-spilling or under- feeding and also controls feed lower and upper clamp set points. The technology is relatively new and has not been widely used in Africa with the only other instal- lation on the continent other than at AGM being at the Palabora copper mine in South Africa, where there are reportedly two MillSlicers on the AG mills. In the case of the AGM installation, DRA worked very closely with the Asanko owner’s team and was responsible for developing an intelligent ‘rules based’ control system to work in conjunction with the MillSlicer instrument. The pri- mary objective of the control system is to control the mill toe angle in order to opti- mise the mill throughput. Bradford and several colleagues from both Asanko Gold and DRA pre- sented a paper on the project at the 14th AusIMM Mill Operators’ Conference held in Brisbane, Australia in August 2018. Entitled Optimisation of Asanko’s Obotan SABC circuit to achieve ‘Project 5 Million’ , it was jointly authored by Bradford, Walter Gift-Agbey, Process Manager at Asanko Gold, Elco Grobler and Paul Morgan of DRA, and the late Thinus Vorster, Group Engineer at Asanko Gold. Says Bradford: “There was a big response to our presentation, which sug- gests that there are many mines which would like to emulate the success we’ve

had at AGM. It needs to be stressed though that the whole process is by no means straightforward and requires much more than simply installing the MillSlicer. It also needs a focused team approach, implementation of a geo-metallurgical treatment plan, which is used for predic- tion of production and crusher mill feed planning, and integration of a knowledge- based control strategy.” Asanko Gold’s achievement in suc- cessfully implementing P5M was recently recognised when it won the ‘Best Performer in Innovation’ award in the recent 2018 Ghana Mining Awards organ- ised by the Ghana Chamber of Mines. It was also recipient of the prestigious ‘Mining Company of the Year’ award which is presented to the mining company that has the highest aggregate results in the categories of Occupational Health and Safety, Corporate Social Investment, Local Content, Environmental Management, Fiscal Performance and Innovation. Commenting on the recognition for AGM, Peter Breese, Asanko Gold’s President and CEO, described it as “a fantastic achievement given that we are still a young business.” He went on to say that the company was very proud to have also received the Innovation award for P5M. “The upgrade from 3 Mt/a to 5 Mt/a has gone extremely well, with the plant consistently achieving above design throughput levels whilst maintaining excellent gold recoveries over the past

three quarters,” he said. Photos courtesy of Asanko Gold

January 2019 _ MODERN MINING _ 65