Modern Mining March 2018

DIAMOND MINING

of the sample at the new Sedibeng plant, together with the treat- ment o f the sc r eened

low-grade in-situ mineralisation that cannot be classified as either a mineral resource or ore reserve and is intended for stockpiling. The Bellsbank sample material was pro- cessed via the newly commissioned bulk sample processing plant facility located at Sedibeng. The plant consists of a scrubber, pri- mary crusher, secondary crusher circuit, plus coarse and fines pan with concentrate being processed on a batch basis through the current Sedibeng DMS and X-ray plant. The facility has a designed nameplate capac- ity of 50 t/h for kimberlite ore and 150 t/h for tailings feed. It has been designed to operate in a dual capacity as both a batch treatment plant for bulk samples extracted from Bellsbank, as well as other regional exploration targets, and as a concentrate retreatment plant to process available tailings material from the Sedibeng mine. There are currently more than 2 Mt of diamond-bearing tailings material sitting at the mine. The plant was purchased for US$0,6 mil- lion from a local dump retreatment operator, Superkolong, a subsidiary of Batla Minerals SA. Relocation and refurbishment of the plant began in July 2017, using exclusively the in-house engineering expertise at Frontier’s contracted associate company’s Kimberley workshop. It was successfully refurbished and wet commissioned at a total engineering cost of approximately US$0,6 million. Frontier says the total capital investment of approximately US$1,2 million can be measured against an estimated replacement value of the plant of approximately US$4,7 million. The entire crushing and screening process

product at the existing DMS plant, and sub- sequent sorting of the diamonds, was over- seen by the CP over a period of five days. Two days were used to thoroughly clean and purge the DMS and final recovery plants before processing the sample.

Frontier will proceed to commission a public geological report accompanied by historic and

current exploration results, including a descrip- tion of the style and nature of mineralisation. This report will consider the results of the next 10 m blast, which will expose the underlying hypabyssal kimberlite. Grade estimations will be established after taking a sufficient bulk sample of the exposed kimberlite. Apart from the Northern Cape proper- ties, Frontier – which debuted on the ASX in January this year – also controls the Star diamond mine, which is located 12 km north- east of the town of Theunissen in Free State Province. Both Star and Sedibeng are well- established underground mines with more than 60-year operating histories. They were acquired by Sedi Diamonds (now a subsidiary of Frontier) in 2014 from Petra. Frontier’s MD is Jan Louw, previously Director of Operations of Firestone Diamonds. Photos courtesy of Frontier Diamonds

Diamonds recovered from the Bellsbank pipe.

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March 2018  MODERN MINING  37