Featured Article: Pump It Up

Save to read list Published by Will Owen, Editor Global Mining Review, Wednesday, 19 April 2023 14:00

Pablo Silva and Jose Longo, Watson-Marlow Fluid Technology Solutions, and Dominic Conybeare, Wardell Armstrong International Ltd, detail how sustainable solutions, such as peristaltic pumps, offer a competitive edge to mining companies amid a rising demand for lithium.

One of the world’s largest lithium producers is benefiting from using peristaltic pumps in its refining operations in Chile, with a reduction in leaks and downtime achieving cost savings at a time of expanding production for the mining company.

To meet rising demand from the burgeoning lithium-ion battery market and amid the global push towards electrification of vehicles, the Chile-based mining company has recently increased its focus on lithium with aims to hit production capacity of 180 000 t of lithium carbonate in 2023.

To ensure its production is at full capacity during this expansion, the mining company is using Bredel Hose Pumps from Watson-Marlow Fluid Technology Solutions (WMFTS) at its lithium processing plant, where lime dosing is the main application. The peristaltic pumps have stopped leaks and cut maintenance downtimes that were experienced with an alternative pump principal that the mining company previously used, which has resulted in chemical costs savings.

The lithium extraction process in Salar de Atacama, the largest salt flat in Chile, begins with brine being pumped out of the ground and into evaporation ponds where the remaining brine is slowly enriched in lithium. Brines high in lithium content are then transported to the mineral processing and refining plant, where pure lithium carbonate and lithium hydroxide are produced. Lithium carbonate and lithium hydroxide are an essential input in the production of the cathode material in batteries used in electric vehicles (EV).

The mining company has used WMFTS peristaltic pumps at its lithium processing site in Chile for the past five years and has recently increased the number it uses to over 50 Bredel and Qdos pumps.

The reliability of the pumps keeps the work area clean, with no lime, compared to leaks experienced with centrifugal pumps. The company has expanded its lithium operations and Bredel pumps have been part of the increase in production. During the last year when this company had doubled its production, Watson-Marlow had sold eight Bredel 65 pumps to them.

For lithium carbonate production, this Chile-based mining company uses Bredel 65 pumps to transfer lime to the reactors, with a flow and discharge pressure of 8 m3/h and 5 bar (2.2 l/sec. and 72.5 PSI) to:

The same pump also transfers lime during the production of lithium hydroxide from the reaction of lithium carbonate and lime, with a flow and discharge pressure of 12 m3/hr and 6 bar (3.3 l/sec. and 87 PSI).

During lithium sulphate production in the press filter, the mining company uses Bredel 40 pumps to transfer lithium sulphate at 2 m3/hr and 7 bar as the pump avoids leaks and has the ability to handle a low flow rate with 30 – 40% solids.

Bredel is widely used in mining applications to transfer corrosive liquids, such as hydrochloric acid. The Chile-based mining company uses Bredel 25 and 32 models and a Watson-Marlow 621 close-coupled pump to pump hydrochloric acid in the lithium carbonate reactors to avoid expensive and toxic leaks, and to get the correct dose according to the process.

Australia is also seeing increased lithium mining activity. In Western Australia, seven Bredel 2100 Duplex and one Bredel 80 peristaltic pumps have been used by a lithium mining company for the thickener and underflow process.

Water conservation is vital in countries such as Australia and good water management reduces disruption to mining operations as well as damage to the environment. Bredel hose pumps can be considered water-saving devices in their capabilities, in the way they handle undiluted tailings and thickener underflow.

Bredel pumps and hoses are the right solution for abrasive slurry. WMFTS hoses perform well in that application. Western Australia mines are in the middle of a desert, so water savings can also be a key for mining companies to use Bredel products, as WMFTS pumps can pump solids content up to 80%. WMFTS products present high reliability, an important factor when the closest town and service staff are more than four hours away.

At the other end of the scale to major lithium suppliers in places like Chile and Australia, peristaltic pumps are also playing a key role as companies scale up their operations or try to establish a profitable lithium production site.

With prices of lithium – called ‘white gold’ by investors – rocketing recently amid increased demand from the EV battery market, existing supply sites are ramping up production and there has been a birth of pilot projects aiming to mine and refine lithium in places like Nevada, US, and Cornwall, UK.

Getting it right at the pilot plant stage is crucial as savings can be made through water, chemical, and energy use, with the right pump for the transfer of slurries or for dosing, as well as being environmentally responsible.

Engineering and mining consultancy company Wardell Armstrong International Ltd has recently provided a lithium pilot plant as well as a modular mineral processing pilot plant for Elementos, an Australia-based pure tin exploration and development company.

Wardell Armstrong built a pilot plant that was looking at recovering tin and since then has developed multiple pilot plants, including one for lithium. The company achieved the targets it set out to meet, in terms of grades, and demonstrated production of a high-grade, low-impurity tin concentrate.

A modular design is at the heart of the Wardell Armstrong pilot plant assembled at its facility in Wheal Jane in Cornwall, UK. Watson-Marlow 600 and 700 series peristaltic pumps are being used for the transfer of material between the various processing stages.

The bigger pumps are all involved in the transport of slurry from one piece of equipment to another; for example, from conditioning tanks to flotation cells, from flotation rougher cells to flotation cleaner cells etc. The main benefit is the ease in which flowrates can be monitored and adjusted. For example, the flotation circuit is usually fed at 2 l/min. Wardell Armstrong uses a lot of the smaller series pumps (Watson-Marlow 300s and 500s) to dose reagents, including flotation activators, depressors, frothers, collectors, pH modifiers, to the flotation circuit. The small adjustments that can be made on these models make them ideal. For example, for the lithium pilot plant it was important to keep the pH at 2.5 with sulfuric acid by dosing at various locations.

Pilot plants like this from Wardell Armstrong test the equipment, chemical engineering methodology, and operations on a small scale before full production. The main benefit of pilot plant testing is to provide metallurgical proof that what has been achieved at a laboratory scale, using a sample weighing a few kilos in mass, in terms of final concentrate grade and recovery can be successfully scaled up, using samples a few tonnes in mass, without detriment to the final outcomes. Wardell Armstrong are also asked for pilot plants when clients need large quantities of concentrates produced for further downstream processing, like environmental testing and thickening/dewatering test work.

Grinding Solutions, another metallurgical laboratory and consultancy service, produced a pilot project for Cornish Lithium, a mineral exploration and development company, which used Watson-Marlow 500 and 600 series pumps for reagent dosing, to dose sulphuric acid in pH adjustment and for slurry transfer. A Qdos 30 metering pump from WMFTS was also used for accurately dosing flocculant into settling tanks at a rate of 10 – 15 ml/min.

Cornish Lithium, which has developed advanced eco-friendly lithium extraction technology from geothermal waters underground, and Geothermal Engineering Ltd. (GEL) together have set up a pilot facility at United Downs, to demonstrate its methods, verify processes, understand costs, and minimise risks. Their aim is the sustainable extraction of lithium and other battery metals in Cornwall.

The plant uses five 500 series cased peristaltic pumps from WMFTS as part of the processing equipment. The 530SN/R2 pumps serve two different parts of the test plant, the first of which extracts lithium from the waters by pumping the brine from a container up through a column containing a large number of beads.

From pilot plant to full scale mineral processing, peristaltic pumps are providing chemical and water savings, while minimising environmental impact and maintenance downtime.

Clog-free and reliable pumps from Watson-Marlow are being used in mining and mineral processing for: transferring viscous slurries, tailings, sludges, reagents and abrasive mixtures, chemical dosing in water treatment, refining extracted minerals, and underground or open-pit dewatering.

Bredel and Qdos pumps can achieve significant savings in water usage. On average, water savings of 71% can be achieved in comparison with typical centrifugal pumps.

Whether handling polymers, flocculants, reagents, abrasive lime slurries, or corrosive chemicals, peristaltic pumps can accurately control the flow, with minimal downtime for maintenance and a very low-cost parts inventory.

Read the article online at: https://www.globalminingreview.com/mining/19042023/featured-article-pump-it-up/

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