PRESS RELEASE: Vedanta Zinc International's Gamsberg zinc project is currently being constructed by ELB Engineering Services.

The samplers from Multotec Process Equipment will allow reliable real-time process results to be generated by the metallurgical plant

The company's process engineer Modisaotsile Nyokong said the equipment supplied to the project includes gravity (shark-fin type) and pressurised (pressure pipe) samplers. Each sampler is custom-designed to suit the flow requirements of each analyser.

The samplers will provide a continuous sample to the online particle size analyser (PSI) and X-ray fluorescence (XRF) analysers. PSI analysers require 100L per minute, while XRF analysers require 100L to 300L per minute.

According to Nyokong, the unique single-stage vezin sampler and double-stage ‘two in one' metallurgical accounting samplers will collect representative final composite sample sizes of less than 20L per shift from streams ranging from 80NB to 700NB inlet-correct.

The Gamsberg mine plans to produce 4 million tonnes of concentrator feed a year from the open-pit mine and an annual 250,000Mt of zinc in concentrate.

Nyokong also highlighted the importance of metallurgical accounting in ensuring that AMIRA standards and best practice are being applied in the plant's sampling applications.

"The metallurgical plant needs to ensure that samples collected from metallurgical accounting samplers are representative of the whole shift operation and are used for accurate metal accounting balances," he says.

The benefit of the total sampling solution supplied by Multotec is to have both a process control sampler and a metallurgical accounting sampler in the same stream. Process control samplers are specimen takers, providing samples that are used for real-time process control purposes.

The ‘two in one' metallurgical accounting sampler comprises two separate sample units in one, with a primary and a secondary sampler unit assembled into a compact unit allowing for a net plug-and-play solution. The design allows easy access, as the primary cutter can be inspected through a bolted hatch on the top and side of the housing. The secondary cutters can also be inspected with ease, through an inspection cover on the top of the secondary housing.

An advantage is that the sampler cutter of the primary unit cuts the full stream of the slurry at constant speed with sufficient volume to collect the sample, minimising sampling extraction and delimitation errors. The sampled slurry then reports to the secondary vezin sampler, where the four cutters cut the full stream of the primary sample.

Multotec's gravity shark-fin type sampler is designed to take a process control sample from a gravity, or non-pumped, process line or launder. The pressure pipe sampler is used to collect samples from pressurised lines. The gravity sampler uses the well-known technique of sampling via a static cutter and is recommended to improve sample representativity for all gravity line applications.