An X-ray fluorescence (XRF) sorting machine has been adapted to create a new application for the sorting of emeralds.
The machine is aimed at improving the security and efficiency of sorting solutions for emeralds.
Before the run-of-mine material reaches the XRF machine, it is crushed to -30 mm and put through a trommel screen for cleaning and further size reduction. After material containing emeralds is ejected from the material stream by the sorter, it is further sorted by hand and graded.
De Beers Group Technology collaborated with Magnum Mining and Exploration on the Gravelotte emerald project in Limpopo province, to employ its sorting equipment.
The company’s sorting equipment also employs X-ray luminescence, X-ray transmission, laser, magnetics and ultra-violet technologies.
According to the group, its sorting technologies have been applied to a range of minerals apart from diamonds, including gemstones like rubies to lower value commodities like manganese and coal.
The mining project noted that the traditional manual method of sorting carried an associated security risk and also led to recoveries that were not optimum.
With the aim of improving sorting methods, the company leased the XRF machine for the duration of its trial mining and the machines are now deployed in the operational environment.
The emerald sorting machine is seen as an important part of the improvement in recoveries and processing security. The project aims to reach a target of around 3-million carats a year as its initial production rate.