image of diamond

Bulk Sampling

Diamond grades are usually expressed in carats per tonne (cpt) or more often, carats per hundred tonnes (cpht). World-wide, kimberlite grades in producing mines vary from approximately 25 cpht to over 400 cpht – it is the average dollar per carat value which is a determining step in the viability of a diamondiferous kimberlite to be a mine.  One metric carat is equivalent to 0.2 grammes in weight, hence, a large volume of kimberlite must be treated to recover diamonds  To obtain a sample to determine either the average value of a statistically valid number of diamonds or to be reasonably certain that the grade is representative of the kimberlite type, samples of usually several thousand tonnes are collected.

Leland opporates a mini-bulk sampling plant where typically one sample is approximately 100 tonnes.  Operation of the mni-bulk sampling plant falls under the control of Dr Alex Dak, Leland's Laboratory and Special Projects manager.  A state-of-the-art one tonne per hour DMS unit was purchased from Bateman's in South Africa and crushing and screening front-end unit was fabricated by a Clarity Mineral Service of company.  To effect diamond recovery a Flowsort X-Ray sorter was purchased. 

The plant was constructed and commissioned from January to March 2008 and has treated approximately 400 tonnes of material to date from four kimberlites.  Diamonds have been recovered.