North Arrow Minerals says it has engaged Imilingo Mineral Processing of Pretoria, South Africa, TOMRA, and Microlithics Laboratories of Thunder Bay, Ontario, to investigate modular diamond recovery design options incorporating TOMRA’s X-Ray Transmission (XRT) sorting technology at its 100% owned Naujaat diamond project in Nunavut, Canada.

The engagement is with a view to recovering diamonds greater than 3 mm (nominally >0.5 ct) in size from a diamond recovery plant, it said.

North Arrow is currently planning for collection of a 10,000 t bulk sample from the Q1-4 deposit at Naujaat and, as part of this work, has initiated an engineering design and costing study of a small-scale mobile diamond recovery plant. The purpose of the sample will be to evaluate diamond size distribution and value characteristics, with emphasis on a distinct population of high-value, fancy, yellow to orangey-yellow diamonds that have been identified in the deposit, the company said.

Ken Armstrong, President and CEO of North Arrow, said: “We are pleased to be working with Imilingo, TOMRA and Microlithics to study diamond recovery plant design options for use in our continued evaluation of the Q1-4 diamond deposit.

“Over the last number of years, TOMRA’s XRT sorting technology has changed the diamond mining landscape by providing an XRT sorting solution that improves diamond recoveries while reducing breakage and water use compared to more traditional diamond recovery circuits. We believe XRT sorting technology can also be used for the evaluation of diamond deposits and is an ideal recovery solution for the Q1-4 diamond population.

“Locating a small-scale diamond recovery plant at or near the project site will also reduce costs, improve logistics and increase local employment and business opportunities for the residents of Naujaat,” he said.

Imilingo’s iPlant packages combine XRT solutions from the likes of TOMRA to sort and deliver feed material in a clean and well classified state, Managing Director, Jaco Prinsloo, told IM recently. Microlithics Laboratories, meanwhile, provides a number of diamond-specific services to clients in North America.

The focus on recovery of diamonds greater than 3 mm is an important component of the study, the company said, with a significant amount of the cost associated with processing past Q1-4 kimberlite samples related to ensuring and documenting the recovery of smaller diamonds (down to 1 mm in size).

Armstrong added: “While information on the 1 mm to 3 mm diamonds is important, most often the value of these diamonds does not impact the potential viability of the deposit being tested. This is certainly the case for Q1-4 where the value and size distribution of the fancy coloured diamond population will be critical in determining the economic potential of the deposit.

“We are therefore looking to design a small-scale mobile plant that can produce a hand-sortable concentrate for the recovery of +3 mm diamonds while saving significant costs and time delays associated with shipping bulk samples south for processing.”

Locating a diamond recovery plant at Naujaat as part of the Q1-4 bulk sampling program is possible due to the deposit’s proximity to marine transportation infrastructure and the improved accessibility that will be provided by a proposed new community access trail, the company said.