Since establishing a presence in Botswana in 2011, mineral processing equipment manufacturer Multotec’s regional office has become an innovative equipment supplier, having started commissioning of a pulping chute last month – a first for the local diamond industry.

The pulping chute is relatively new to the company’s portfolio of products, having been tested and installed in late 2019 by diamond miner Ekapa Minerals at its combined treatment plant, in Kimberley, South Africa.

The innovation, developed by Multotec, comprises a pulping chute that effectively replaces the traditional rotary scrubber in the ore processing circuit.

Multotec Botswana GM Peter Mbada emphasises that the pulping chute performs the scrubbing action faster and more cost effectively than a traditional rotary scrubber, while its maintenance requirement is also lower.

Multotec Botswana’s inaugural pulping chute installation was done at a diamond mining operation. Mbada says the equipment will save the mining operation on electricity costs as well as on maintenance, resources and associated costs, since the chute has no moving parts. The existing scrubbers run on tyres and these have historically caused operational problems, mainly owing to slipping, especially during the wet seasons.

“With the static pulping chute in place, all that is history.”

After completion of the chute commissioning, it will run under observation for about three months. The potential rollover of the equipment to other plant sections will then be considered. There is a significant likelihood that this innovative and cost saving solution will be extended to eventually replace all scrubbers, both primary and secondary, in the processing circuits.

Pulping Chute Workings

The patented wave generators enable the pulping chute to use the gravitational energy from the slurry flow to create a constant turbulent mixing action that releases the mud, clay and slime sticking to the kimberlite particles.

In addition to improving scrubbing efficiency, the chute also eliminates the cost of replacing scrubber liners and the downtime that was required. The cost of replacing the steel shell of a scrubber can be significant, as it is constantly subjected to stress, wear and fatigue.

The pulping chute is a stationary and much simplified innovation, focused on the scrubbing of fines less than 32 mm in size. Slurry deflectors located at the top end of the scrubbing chute direct at least part of the slurry away from the scrubbing chute floor. It then curls into an arched form, which flows backwards into the approaching flow of slurry, creating the turbulent scrubbing effect.

Multotec custom-designs its chutes to suit the application and can increase chute capacity to up to 800 t/h. This is achieved with no moving parts, bearings, hydraulic packs or girth gears.

The only power required is to supply material and water to the receiving chute and feed the scrubber, after which gravity takes over and provides the required energy.

The pulping chute’s application is not limited to diamonds and is also ideal for use in the coal, platinum, chrome, iron-ore and mineral sands mining markets; however, Mbada says that, in Botswana’s case, Multotec will focus on supplying the diamond and coal markets.

Another positive innovation Multotec Botswana has been testing the application of Mato belt cleaners – traditionally used in the coal industry – in the Botswana diamond mining industry over the past year.

These belt cleaners have been in operation under observation for at least ten months at a diamond mining operation and have performed exceptionally well with minimal maintenance, consequently, resulting in cost savings for the customer and, ultimately, lower production costs. This has been particularly beneficial during the volatile market for diamonds caused by Covid-19.

Mbada says the Mato belt cleaners will also work well in copper mining applications once these projects come on stream in Botswana.

There has been “a resurgence” in copper investment, as well as coal and gas projects, in the country as a means of diversifying away from its dependence on diamonds.

Multotec Botswana’s head office is located in Lethlakane, with two supporting site offices in Jwaneng and Orapa for effective field support.

The Botswana branches offer screening media solutions, cyclones, magnetic separators, samplers, centrifuges, mill and scrubber linings, as well as wear linings, to the diamond, coal and copper mining markets and quarries.

Mbada says that Multotec Botswana believes in citizen empowerment and giving back to the communities in which it operates. To that end, 98% of the company’s employees are Botswana citizens. Multotec Botswana also supports local entrepreneurial endeavours by engaging citizen businesses as subcontractors on various projects and contracts and supports them in growing their businesses.

The company has adopted two schools, one in Letlhakane and the other in Sekoma, near Jwaneng. To uplift these schools and their students who are predominantly from the local communities, the company has been involved in legacy projects that will last for as long as the schools exist, apart from assisting with stationery, printers and other accessories.

Multotec Botswana is closely involved with local communities and, recently, handed over the Leobo they had built for the local kgotla and which has now become a hub of various economic-empowerment projects for the youth.

He also adds that the company provides skills development and product training for all its employees, at different levels.