Tag Archives: John Britton

Multotec pulping chute advances at Ekapa open opportunities for fines scrubbing tech

The performance of Multotec’s pulping chutes at Ekapa’s diamond treatment operation in Kimberley, South Africa, over the past couple of years has, the company says, opened the door to quicker and more cost effective fines scrubbing.

According to John Britton, Technical Consultant at Multotec, the two pulping chutes have achieved outstanding results, helping the customer’s facility to cost effectively increase the throughput of its Combined Treatment Plant (CTP).

“At our recent two-year inspection of the plant, we found that the wear rate on the ceramic lining of the wave generator was only 20 mm over that 24-month period,” Britton says. “Each chute was processing 380 t/h of recrushed kimberlite product with 380 cu.m of water, rushing down a 28° incline.”

Multotec’s patented wave generators use gravity to create a constant turbulent mixing action in the slurry flow that releases the mud, clay and slime sticking to the kimberlite particles. The chutes are positioned to receive material from the high pressure grinding rolls’ interparticle tertiary crushing circuit. Multotec’s engineered alumina ceramic tiles give the chutes and wave generators high wear resistance, it says.

“The chutes exceeded our expectations in how well they separated the clay from the kimberlite ore and broke up clay balls in the material stream,” Britton says. “This has really demonstrated the long-term capacity of our design to deliver results with hardly any maintenance or operator intervention.”

He highlights that the chutes are stationery structures that rely on the kinetic energy being created by the in-rush of slurry flow over the wave generators. This makes the solution much simpler and less energy-intensive than traditional rotary scrubbers with motors, drives and gearboxes. The chute can also achieve its results much quicker, as the material flow passes through in just three to four seconds.

Ekapa CEO, Jahn Hohne, says he has been impressed by how well the chutes have performed as an alternative to a considerably more costly scrubber circuit, and having delivered a 20% increase in throughput through the plant and making a positive economic contribution to overall efficiency. Hohne says he admired Multotec’s innovation capability and looked forward to even further improvements in the design.

Britton notes that, after conducting the wear inspection of the chutes, there were modifications Multotec was planning. One of these related to the retarder bars, which slow down and divert the slurry flow.

“We believe we can achieve even better results if we remove some of the retarder bars and install another set of wave generators,” he says. “Our results suggest that this will get the ore material even cleaner, before it reports to the screen, the conveyor belt and finally the dense medium circuit.”

The success of the pulping chutes at Ekapa has led to considerable interest from other diamond producers in southern Africa, he added.

Multotec solution scrubs up well at Ekapa Minerals diamond plant

A revolutionary new concept in fines scrubbing is proving to be a game changer for Ekapa Minerals at its Combined Treatment Plant (CTP) in Kimberley, South Africa.

The innovation, developed by Multotec Wear Linings, is processing both virgin underground kimberlite as well as tailings for retreatment at the CTP. The solution is effectively a pulping chute that scrubs and washes the re-crushed product after it has passed through the high pressure grinding rolls (HPGR) inter-particle tertiary crushing circuit.

The important advantage here, according to Multotec Wear Linings Projects Sales Manager, John Britton, is that it performs the scrubbing action faster and more efficiently than a traditional rotary scrubber would, and at much lower cost.

Multotec commissioned two of these pulping chutes at Ekapa Minerals in late 2019, where they have been operating consistently and in line with expectations. With the use of patented wave generators, the pulping chute uses 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.

According to Ekapa Minerals CEO, Jahn Hohne, the pulping chutes are a welcome contribution to the company’s cost saving efforts, and a clear demonstration of Multotec’s expertise in developing value-adding solutions in the mining sector.

“The dual chute pulping plant is ideally suited to de-conglomerating the HPGR cake product and is exceeding expectations in efficiency and effectiveness at over 600 t/h, which is a major relief on the existing overloaded pair of CTP scrubbers,” he said. “The net result is a meaningful increase of up to 20% throughput capacity of the entire processing plant which substantially improves the economy of scale of CTP, feeding directly to the bottom line.”

Britton highlighted the efficiency of the system, which is able to aggressively scrub the material in just three to four seconds as it passes through the chute. This represents just a fraction of the usual retention time in a rotary scrubber, which is three to four minutes, according to the company. He also emphasises the drastic reduction in running cost which the pulping chute achieves.

“From our experience of plant layouts and flow diagrams, it is clear that fines scrubbers are significant contributors to a plant’s capital, operating and maintenance costs,” Britton said. “Scrubbers are equipped with large drives with gears and gearboxes to rotate the drum. They are high consumers of power and require mechanical component maintenance which means higher operating costs.”

Substantial structures and supports are also needed for the scrubber and its drive mechanisms. In designing the pulping chute, Multotec sought a simplified solution, Britton says. In addition to improving scrubbing efficiency, the objective included reducing the cost of replacing scrubber liners and the downtime that this demanded. The cost of replacing the steel shell of a scrubber – which is constantly subject to stress, wear and fatigue – was another cost to be considered.

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

Britton said: “We custom-design the 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. These actions are also required to feed the scrubber, then gravity takes over and provides the required energy.”

Maintenance is also streamlined by designing the chute in segments. Should one segment be wearing more than others, it can be quickly removed and replaced – putting the chute back into operation while the original segment is refurbished as a spare.

Britton says the pulping chute has drawn interest from other diamond producers in southern Africa, Australia and Canada. It can also be applied in commodity sectors such as coal, platinum, chrome, iron ore and mineral sands.