Tag Archives: Willem Slabbert

Multotec addresses grade control, recovery issues with RAMA sampling system

Mineral processing, Mining services, , , , , , ,

With its latest sampling system that aligns with metallurgical accounting standards, minerals processing equipment company Multotec says it now offers unprecedented levels of accuracy for effective plant optimisation.

The company’s Realtime Automated Metallurgical Accounting (RAMA™) system promises to deliver significant value by unlocking higher mineral content through improved grade control and recovery, as well as by optimising the consumption of reagents. The system brings together three sampling disciplines – metallurgical accounting slurry sampling, sub-sampling, preparation and analysis – into one solution, it says.

“By integrating our advanced samplers with a sample preparation system that meets metallurgical accounting standards, we can feed online analysers with a fully representative and accurate sample,” Modisaotsile Nyokong, Process Manager at Multotec, says. “While analysers can be accurate instruments, they cannot provide meaningful results if they are fed with inaccurate samples.”

Nyokong highlights that the RAMA online analysis feed preparation system extracts regular and full sample increments from slurry flow streams according to AMIRA P754 metal accounting standards, best practice standard and Theory of Sampling (TOS). This eliminates more than 80% of the total sampling error and allows real time process control to be conducted to the highest standard, according to the company.

“Samples are extracted from the production flow using automated mechanical samplers which are TOS compliant,” he says. “This is achieved by taking full cross-cut samples that are representative of the flow stream.”

The analysed slurry is therefore unbiased, presenting an accurate reflection of all the key parameters such as particle size, slurry density, settling velocity and mineral grade, Multotec claims. Nyokong explains that process control samplers – including pressure pipe, poppet and shark fin type samplers – have traditionally been used to feed online analysers. However, these primary samplers do not comply with the TOS, with the result that poorly represented samples are analysed with high levels of precision – a futile exercise.

“Our advantage with the RAMA system lies with feeding representative samples to online analysers, using correct sampler designs,” Nyokong says. “This produces real-time results that represent the flow stream and are free of error or statistically significant bias.”

Multotec’s slurry sample preparation solution prepares and treats each analysis stream in its own line, making it ideally suited to analysers that deal with streams individually. This avoids cross-contamination. Where multiple streams are analysed through the same analyser source and detectors, some cross contamination of streams can occur with different grades or mineral properties – undermining the accuracy of the result.

Over an analyser multi-stream cycle, the RAMA system can collect composite samples for each stream, according to Willem Slabbert, Sampling and Magnetics Product Specialist at Multotec. This means the analyser does not measure the instantaneous off-take stream ‘sample’ from the traditional in-line continuous discharge like process control samplers – which is only done about 30 minutes apart.

“Rather, it measures the performance of each stream through multiple composite samples taken over the 30-minute interval,” Slabbert says “This reduces the grade or quality variability per flow stream, and gives the plant manager a more representative monitoring of minimum and maximum process conditions – with precise values.”

The problem with ‘snapshot’ sampling of process control samplers is that stream properties can fluctuate before and after the analysis., meaning the fluctuation is not captured in the results. By contrast, the RAMA system’s composite sample accounts for all process variations over the analysis period, according to Multotec.

Slabbert reiterates that sample analysis results are only as good as the sample presented for analysis, pointing out that this applies as much to online analysers for process control as it does to conventional laboratory analysis for metallurgical accounting.

“RAMA is also a cost saving solution, as separate process control samplers are no longer required,” he says. “The samplers’ purpose in our system is doubled up for both metal accounting and for process control – without the need for any compromise.”

Configured in a containerised and modular design, RAMA is a compact and mobile system. This allows for easy installation and retrofitting into any plant operation, where it can feed any type of online analyser. It can also be readily transported and commissioned, with flexibility for expansion where necessary. Layout options are available for plants that have primary and secondary sampling with a subsequent containerised sample preparation stations, as well as for those with primary sampling only and separate secondary sampling preparation.

The RAMA system allows analysers, for the first time, to be fed with representative samples taken from the production flow stream, according to the company.

Multotec added: “The innovative combination of existing equipment with proven track record into a modular, containerised solution will bridge the gap between metallurgical accounting accuracy and accurate process control.”

Slabbert concluded: “The advantages of this novel combination of sampling global best practices into process control applications will unlock value for both analyser calibration as well as optimal, dynamic process performance.”

Multotec provides Guinea bauxite verification with sampling equipment

Base metals, Mine operation news, Mineral processing, Mining equipment, Mining services, , , , ,

Multotec Process Equipment’s high-precision sampling equipment has found a home in Guinea, with bauxite producers in the West African country using the South Africa-based company’s tools to verify the quality of mined material before it is shipped overseas.

The company has recently provided two tariff sampling plants to a major bauxite producer in the country, including what is possibly one of the largest hammer samplers in the world, it said.

One of the plants is located at the bauxite mining operation itself, while the other is at the export facility where the high-grade bauxite is loaded onto ships.

According to Willem Slabbert, Sampling and Magnetics Specialist at Multotec Process Equipment, the samplers serve a vital role in representatively measuring the quality of the material mined and then exported, as well as its physical characteristics.

“At the mine, the sampling plant gives the mining company and their third-party mining contractor a scientific basis on which to check compliance with their contractual requirements,” Slabbert says.

“Similarly, the plant at the export facility assures the end customer of the quality of bauxite they are purchasing.”

The solution designed for this specific application includes hammer samplers, double-roll crushers, rotating plate dividers, feeder conveyors and barcoded carousels to link the sampling plant’s hourly performance to the indexed samples produced, Multotec explained. There is also protection equipment – a moisture analyser, overbelt magnet and metal detector – and inter-sampling plant conveyors.

“The plants were designed as a holistic solution, to deliver measurements in line with the international standard ISO8685 – ensuring that both sides of a contractual agreement can feel confident in the results,” Slabbert says. “They are also fully automatic and PLC-controlled for maximum efficiency.”

He highlighted that the sampling and materials handling solution was based on extensive test work carried out at Multotec’s facilities in Spartan, near Johannesburg. Crusher tests were also conducted on the specific bauxite, which comprised a substrate material with very hard embedded nodules.

“We identified custom-designed, heavy-duty, double-roll crushers as the optimal solution to deal with the extreme hardness of the nodules in the material,” Slabbert says. “The abrasiveness and stickiness of the Guinean bauxite also required low-friction liners to be designed into each plant.”

Multotec also has a West Africa branch in Ghana to supporting its installations. This branch also sources local components for customers.

Multotec Process Equipment has experience in sampling bauxite in Guinea, says Slabbert, with a sampling plant installed two decades ago for another bauxite producer.

Multotec on the front line of West Africa mineral sampling scene

Environmental, Mineral exploration, Mining services, , ,

Multotec Process Equipment says the growth and diversification of West Africa’s mining sector is making the precision of mineral sampling a “vital priority”.

For over two decades, Multotec has been active in the West Africa market, with its samplers at over 30 sites in countries including Ghana, Liberia, Burkina Faso, Guinea, Sierra Leone, Mali and Guinea-Bissau. A range of commodity sectors use the equipment for both slurry and dry sampling applications, among them gold, bauxite, iron ore and heavy minerals.

Multotec has also presented representative sampling training courses explaining the practical aspects of implementing the Theory of Sampling (TOS).

Willem Slabbert, Process Manager at Multotec Process Equipment, said: “In bulk minerals like bauxite – where our sampling plants have been in operation with a major West African producer for 17 years – the sampling protocol and ‘correctness’ of equipment design is key to ensuring bottom-line success.”

He highlighted the importance of reproducible and accurate sampling – cumulatively termed representative – at the interface between the mine and port, and on the ship-loading conveyor to the client.

The sampling, which must comply with ISO standards and best practice as prescribed by the TOS, confirms the mine is supplying product to the end-customer’s contractual specification. “Any imperfection in the sampling process can lead to unnecessary contractual disputes and potential financial losses for the mine or client,” Slabbert says.

Multotec supplies wet slurry samplers to several gold mines in West Africa, who rely on good gold accounting and reconciliation at their processing plants. The equipment is popular among large gold producers as well as the smaller entrants, according to the company.

“With a comprehensive range of Two-In-One, primary and ancillary samplers, we are able to tailor each installation to the customer’s specific application,” Slabbert says. “This means accommodating variables like throughput rates and slurry densities, including accounting for grade variability from various mine sources feeding a single processing plant, in many of the West African deposits.”

For brownfield projects, Multotec can design solutions to suit and fit the structural constraints of the customer’s existing infrastructure.

Local service support is available from Multotec’s Ghana branch as well as regional agents and service providers operating in other countries. This ensures a point of contact as first line of support and, drawing on its expertise across a range of disciplines, Multotec can put specialists, engineers, design draughtsmen and millwrights to work on projects throughout the West African territories.