A new concept in fines scrubbing has been installed by Ekapa Minerals at its Combined Treatment Plant in Kimberley, processing both virgin underground kimberlite as well as tailings for retreatment.

The innovation, developed by Multotec Wear Linings, is a pulping chute that scrubs and washes the recrushed product after it has passed through the High-Pressure Grinding Rolls (HPGR) interparticle tertiary crushing circuit. Multotec emphasises that the chute performs the scrubbing action faster and more efficiently than a traditional rotary scrubber and at a lower cost.

With the use of patented wave generators, the pulping chute uses the gravitational energy from the slurry flow to create a constant turbulent mixing action that releases the mud, clay and slime sticking to the kimberlite particles.

According to Ekapa, the pulping chutes have contributed significantly to its cost saving efforts. The company explains that the dual chute pulping plant is ideally suited to de-conglomerating the HPGR cake product and is exceeding expectations in efficiency and effectiveness.

The system is designed to aggressively scrub the material in just three to four seconds as it passes through the chute – a fraction of the usual retention time in a rotary scrubber, which is three to four minutes, and the efficiency of the new concept is said to translate to direct cost savings.

The pulping chute is stationery and has a more simplified design, focused on the scrubbing of fines less than 32 mm in size. Slurry deflectors located at the top end of the scrubbing chute direct at least part of the slurry away from the scrubbing chute floor. This curls into an arched form which flows backwards into the approaching flow of slurry, creating the turbulent scrubbing effect.

Maintenance is also streamlined by designing the chute in segments, allowing for individual segments to be removed and replaced if necessary.

Multotec highlights that the pulping chute has drawn interest from other diamond producers in Southern Africa, Australia and Canada and that it can also be applied in commodity sectors such as coal, platinum, chrome, iron-ore and mineral sands.