Modern Mining September 2018

EQUIPMENT

Vedanta’s US$400 million Gamsberg zinc project near Aggeneys in the Northern Cape will use process control and metallurgical accounting slurry samplers supplied by global specialists Multotec Process Equipment. The project – now commissioning – is being constructed by ELB Engineering Services. Samplers will give real-time

A ccording to Modisaotsile Nyo- kong, Multotec Process Equip- ment’s process engineer, the process control samplers will provide a continuous sample to the online population stability index (PSI) and X-ray fluorescence (XRF) analysers. This will enable real-time results to be generated for management and operators at Gamsberg. “Our unique single-stage vezin sampler and double-stage ‘Two In One’ metallurgical accounting samplers were supplied for streams ranging from 80 NB to 700 NB inlets, to collect representative final composite sample sizes of less than 20 litres per shift,” says Nyokong. The Gamsberg mine plans to produce 4 mil- lion tonnes of concentrator feed a year from the open-pit mine and an annual 250 000 tonnes of zinc in concentrate. The process control samplers supplied include gravity (shark fin type) and pressurised (pressure pipe) samplers, with each sampler custom-designed to suit the flow requirements

of each analyser. PSI analysers require 100 litres per minute, while XRF analysers need 100 to 300 litres per minute. Nyokong stresses the importance of best practice metallurgical accounting designs ensuring Theory of Sampling and AMIRA standards are applied and considered when proposing and implementing sampling solu- tions for customers. “The metallurgical plant needs to be sure that samples collected from metallurgical accounting samplers are representative of the whole shift operation and are used for accurate metal accounting balances,” he says. “Process control samplers, on the other hand, are vital specimen takers, providing samples that are used for real-time process control purposes.” Nyokong highlights that both metallurgical accounting and process control slurry samplers are used in commodities including gold, plati- num and base metals. The benefit of the total sampling solution supplied by Multotec is to have both a process control sampler and metal- lurgical accounting sampler in the same stream. The ‘Two in One’ metallurgical accounting sampler – as the name suggests – comprises two separate sample units in one. The primary and secondary sampler units are integrated into one unit allowing for a plug-and-play solution. The unit can be entirely supported to verti- cal pipework by its inlet flange in an in-line or tank mount position or in the case of larger units using additional brackets on the side of the housing. Ease of access is enhanced allowing the primary cutter to be inspected and accessed through a bolted hatch on the top and side of the housing, while the secondary cutters can also be inspected through an inspection cover on the top of the secondary housing. The primary and secondary drive units are self-contained and situated on the top of the units. The blades of the primary and secondary cutters are easily accessible and replaceable, with some adjustment possible on the primary cutters. “This design makes for efficient and effec- tive sampling,” says Nyokong. “The slot width

Dise Nyokong, process engineer at Multotec Process Equipment.

Timed vezin sampler fitted with an IE3 Premium Efficiency motor to provide constant cutter travel through the stream in accordance with the Theory of Sampling.

46  MODERN MINING  September 2018