In a press release dated 29th January 2018, ALROSA , the world’s leading diamond mining company, announced that its subsidiary company, the Saint Petersburg based Bourevestnik Inc., the world’s biggest designers and manufacturers of X-ray sorters for enrichment of diamond bearing ore and X-ray analytical instruments for various industries and applications, had supplied and commissioned a set of 27 X-ray luminescence sorters at the new recovery plant of the Cullinan diamond mine in South Africa.
The Cullinan Diamond Mine, previously known as the Premier Diamond Mine, acquired by Petra Diamonds Ltd. in 2008 and presently having a stake of 74% in the mine, became renowned as the main source of blue diamonds in the world in the 20th-century, a position which it still enjoys. The mine is also famous for its large, high-quality, Type IIa, D-color/Top color diamonds, known variously in superlatives as “purest of the pure,” “whiter than white,” “brighter than bright,” “diamonds of the purest water” etc. a reference to the absence or presence in undetectable quantities of nitrogen impurities, which impart color to the diamonds. The existence of such diamonds in nature is rare and constitute only about 1-2% of all naturally occurring diamonds.
Petra Diamonds Ltd. decided to install Bourevestnik’s X-ray diamond sorting machines at their recovery plant in the Cullinan Diamond Mine, after an exhaustive study and assessment of the different diamond recovery technologies available in the market that may be used, taking into consideration the unique characteristics of the Cullinan ore. Their study confirmed the high recovery efficiency of all types of diamonds by the Bourevestnik sorters, including low-luminescent Type II diamonds, which characteristically show a low level of luminescence under X-ray exposure.
In keeping with Petra Diamonds specific requirements for primary recovery, re-concentration and final concentrate treatment of diamond bearing ore, with a sizing range of -75 mm +1 mm, according to the Russian classification, Bourevestnik Inc. supplied and installed 27 sorters. The processing of run-of-mine material with a size fraction of -75 mm +6 mm will also be done directly using X-ray sorters instead of dense media separation.
Apart from the supplying of the X-ray sorters Bourevestnik, Inc. has also undertaken the installation and commissioning of the sorters, as well as training the technical personnel to man these machines and the supply of spare parts for the maintenance of these machines.