Company Solutions Address Minerals Processing Inefficiencies (September 2017)

To address water contamination in the minerals processing sector, processing specialist Multotec is installing its CleanTec ion-exchange system, which is designed for the removal of soluble elements from process water, at operations in Oman and soon in the Democratic Republic of Congo.

The first order was placed in July and Multotec will install and commission the equipment from this month.

Multotec Process Equipment MD Rikus Immink tells Mining Weekly that the CleanTeQ technology, which was introduced to the South African mining industry early 2016, provides a green solution for the mining industry, which is “probably considered as one of the dirty industries that contaminate natural resources.”

This technology can also recover valuable minerals, such as PGM’s, silver and gold, from effluent streams.

Multotec is also developing solutions for ultrafine mineral recovery. Ultrafine recovery involves spiral gravity concentration technology to recover material as small as 10μmfrom chrome or iron-ore streams.

Immink says the company’s first test unit, destined for ultrafine recovery, is going to a chrome mine, in Zimbabwe, where it will be tested. It has been delivered to the mine and test work will continue into the next year.

“We also offer dewatering cyclones that provide mines and minerals processing plants with the ability to recover water from their tailings operations with the added benefit of reducing water on tailings dumps and, therefore, reducing underground water contamination.”

Meanwhile, Multotec is experimenting with radio frequency that entails equipping the ceramic liner of its dense-medium separation (DMS) cyclones with a radio-frequency instrumentation that may allow for wear measuring of DMS cyclone liners.

Immink notes that Multotec considered inserting RF chips in the ceramic manufacturing process, bit it is not robust enough to handle such hot temperatures.

“The challenge with using radio frequency is its sensitivity to the firing process used to manufacture the ceramic liners,” he explains.

Multotec will undertake further testing to increase the robustness of other radio-frequency technologies before taking it to market.

Further, the company is doing test work on its ceramic-lined DMS cyclones by installing wires into the tiles. This test work entails picking up a current when ceramic tiles wear at different points when the medium makes contact with the wires to determine the extent of wear.

Immink says this process requires careful maintenance, as the wires can be easily damaged when taking apart cyclone components.

Multotec does on site test work on new technologies, prototypes or products for at least a year to ensure trust and confidence in its products.

“A high-quality mineral processing product will give you an improved yield because,” avers Immink, adding that there is a correlation between beneficiation yield or metallurgical efficiency and the quality of the equipment used.

Challenging Process

He points out that the problem leading to minerals-processing or metallurgical inefficiencies is misplacement, which refers to valuable minerals ending up in the wrong process stream.

Process Engineers often start seeing variances with mineral-beneficiation equipment on mines when equipment knowledge and process control is neglected.

“You have to adjust the density of the dense media cyclone cut to ensure that you always cut between the product and the discard. If you misplace a diamond, owing to varied cutting, it can cost you more than the equipment itself.”

Therefore, Multotec emphasises the need to be well informed about the effective operation of beneficiation equipment and its maintenance by a qualified person.

“Mines have had to cut costs, owing to low commodity prices and general economic instabilities, at the cost of capital investment,” Immink highlights.

During the lean times a lack of metallurgical experts develops, therefore, Multotec offers plant optimisation services. These entail the specialised evaluation of a plant, sampling and testing of its products, enabling Multotec to determine and implement the most effective minerals- processing methods or the best metallurgical efficiency.

“We provide mines with a local presence of expertise so that they can optimise the metallurgical specialists at their operations.”

Additionally, Immink says clients are sometimes not aware of what the quality level is of their final export product, owing to a lack of sampling, because it is expensive and considered as a non-productive process.

“However, not knowing your final-product quality leads to conservatism that can increase chances of over-beneficiation of the product at lower yield,

Immink mentions that Multotec installed a sampling plant at State-owned utility Eskom’s Kendal power station, in Mpumalanga, to ensure that coal being used for power generation is of a consistent quality.

One of the challenges that minerals processing plants have to deal with, include the high cost of replacing capital equipment, the labour intensity involved in changing out heavy equipment, such as a DMS cyclone, and production downtime while staff have to comply with safety regulations while equipment is being replaced.

Immink points out that Multotec strives to be a “plug-and-play” solutions provider, providing installation, maintenance and delivery of high-quality equipment.

Next up for mineral processing

Minerals processing specialist Multotec says the evaluation of surface properties, which entails particle interaction with equipment, is an upcoming trend for mineral processing plants.

The company has, in conjunction with the University of Pretoria, been researching surface properties of process equipment.

This project entails producing more favourable surface properties using a specific material to improve metallurgical efficiency.

“We first looked at our existing surfaces under an electron microscope within a cyclone,” says Multotec MD Rikus Immink.

He adds that it is an elaborate process that will require testing for at least a year before concrete conclusions can be made.

Further, Immink notes that another pertinent trend for minerals processing is using and integrating smart technologies and equipment, such as cell phones, with the processing plant environment.

This type of technology can generate performance curves, record and report plant operation conditions and, subsequently, allow for calculations that result in more informed decision-making.

Immink concludes that Multotec will continue to embrace these trends to stay at the cutting edge of minerals processing and metallurgy.