Tag Archives: scrubbers

SEW-EURODRIVE helps gear up scrubber project at De Beers Venetia mine

Drive technology specialist SEW-EURODRIVE says it is installing four of its large segmented girth gear systems at De Beers’ Venetia Diamond Mine in Limpopo province, South Africa.

Venetia mine, in operation since 1992, is upgrading its two primary scrubbers and two secondary scrubbers, and the girth gear replacement is an integral element of this project, according to SEW-EURODRIVE.

According to Bruce Farthing, Project Engineer at SEW-EURODRIVE, the order was placed in 2020 and all four units were manufactured and delivered within six months. This short lead time was achieved despite the global disruptions caused by the COVID-19 pandemic.

“We have planned the installations in close collaboration with Venetia mine, making sure our teams are ready when the mine’s shutdown periods allow,” Farthing says. “The first girth gear was installed on one of Venetia’s secondary scrubbers in September 2021, confirming the accuracy and duration of our installation procedure.”

The expertise of the installation team was brought to the fore by the scrubber’s specific design. The bearing design in particular makes it impractical to bring the whole drum to ground before changing over the girth gear, according to the company. Instead, the replacement has to be conducted with the drum in situ, at a height of about three storeys high.

“In the first installation, we, therefore, assembled the girth gear on the ground, lifting it into position once the old components had been removed from the scrubber,” he says. “The challenge, of course, was to ensure no damage to any of the new components, which we managed with careful planning and experienced execution using large overhead cranes.”

These large girth gears measure 5.3 m in diameter and weigh about six tonnes each. Given the scale of the equipment, the segmentation of the gear makes for easier transportation and handling. He explains that each girth gear is made up of 10 identical segments which are easily assembled on site.

“The segments allow for relatively quick assembly with less lifting equipment,” Farthing says. “A further advantage is that individual segments can be kept in stock and used as replacements in the event of a breakdown – keeping downtime to a minimum.”

The second and third installations – to be conducted on the two primary scrubbers – are scheduled for later this year. With the limited time available during a plant shutdown, the installation team adopts a 24-hour work cycle.

The contract includes the supply of SEW-EURODRIVE’s large two-stage industrial gearboxes and the external pinions to drive the girth gear. The motors are coupled to the gearboxes using a fluid coupling on a purpose-built, drop-in baseplate. Smaller gearboxes from SEW-EURODRIVE’s X series range are also coupled to the main gearbox as auxiliary drives for commissioning and maintenance.

Farthing notes that the company’s segmented girth gear systems have recently been a popular choice for South African customers, with six orders being received within about a year. Apart from the four supplied to De Beers Venetia Diamond Mine, SEW-EURODRIVE also recently supplied these solutions to applications in a paper mill and a cement mill.

Multotec liners scrub up nicely for Morocco phosphate mine

In one of its largest scrubber installations to date, Multotec Rubber is helping a phosphate mine in Morocco achieve new levels of efficiency thanks to the installation of customised liners.

The scrubbers measure 6.5 m in diameter and 11 m in length – large dimensions necessitated by the process plant throughput of 12 Mt/y. The installation, conducted during the March quarter of 2019, was carried out in response to a serious challenge faced by the customer. The existing head plates were wearing out at double the rate of the shell plates. This was leading to additional maintenance shutdowns during the life of the liners, with associated extra costs.

According to Mohamed Trabelsi, Senior Sales Engineer at Multotec Rubber, the collaboration with the customer included sending a Multotec team to site to first assess the situation. Multotec already had a longstanding relationship with the customer at this process plant, with Multotec trommel screens having operated successfully at the plant for over three years.

“Our team of engineers were on site to gather vital operating information including throughput tonnages, particle size, charge levels and rotational speed,” Trabelsi said. “We also assessed the variable speed drive system.”

This data was processed using the Rocky DEM simulation software, in which Multotec Rubber has made a significant investment. Leveraged by engineers, this software can simulate the full lifecycle of liners and predict when the scrubber will no longer perform efficiently, according to the company.

Rocky DEM allows engineers to accurately simulate all operating parameters in the scrubber. These include the shape and size of ore particles in the slurry being fed into the scrubber slurry, the charge level, the linings, attrition rates, particle trajectories and the scrubber’s rotational speed, Multotec Rubber says.

“We can therefore simulate the actual operating conditions of the scrubber, as well as the performance of the head and shell liners,” Trabelsi said. “Upon our assessment of the results, it was found we needed a different configuration of liners to the previous one in this application. In fact, the solution was a uniquely designed liner configuration – quite different to what is traditionally used.”

He notes that, in Multotec’s experience of high throughput scrubber applications, it is critical to lift the material away from the head plate, thereby alleviating the sliding abrasion which causes excessive wear.

“Our objective was to ensure optimum wear life with the lowest total operating costs,” Trabelsi said. “Efficiency was enhanced by ensuring that the liner profile configuration was suited to the specific operating conditions. By doing this, the wear life in this application has been improved.”

Since installation, the liners have been performing in line with the customer’s expectations and are expected to have a lifespan of over five years. These lifecycle predictions also allowed the payback period to be accurately determined, assisting the customer in making the best operational and financial decision, the company said.

The liners are locally manufactured at Multotec Rubber’s ISO 9001:2015 facility near Johannesburg, South Africa, which has benefitted from continued investment in technology over the years, the company said.

“Our quality manufacturing facility expedites the production of liners engineered for individual applications,” Trabelsi said. “The entire process from design stage to installation took just 12 weeks – in response to the urgency resulting from the premature failure of the previous scrubber lining installation.”

Trabelsi also noted that – even after finding an appropriate solution – mines must constantly anticipate changing conditions in their process plants.

“As mines develop, the orebody changes; this brings changes to their throughput capacities and mill operating parameters,” he said. “If a process plant has liners that have run for 10 years, it is not necessarily a given that this liner configuration is still suitable for the application.”

He emphasises that it is critical to conduct an assessment exercise in every application, before quoting on a replacement liner. Most importantly, the liners should be engineered in accordance with the current operational parameters of the mine.

“This is why Multotec Rubber considers it so important that our engineers go to site and assess the actual mill operating data for themselves,” he said. “This makes it possible for us to gain access to the information from the plant operating system, so that the best solution can be engineered for the mine.”

Correctly designed liners will offer greater energy efficiency and reduce media consumption, according to Trabelsi. This is significant, as energy input and media consumption account for around 80% of the grinding costs in the plant – depending on the application.

“The more we are able to simulate, the more accurate information becomes available,” Trabelsi said. “We are then able to accurately predict the savings and payback period that could be expected at the plant – as a result of improved efficiency and reduced power consumption per tonne.”

MechProTech collaborates with Vesconite Bearings on new mills, scrubbers

Mineral processing equipment manufacturer and designer, MechProTech, has introduced hydrodynamic composite bearings made from Vesconite Bearings’ vesconite thermopolymer plates for use on mills and scrubbers for the mining industry.

These plates, which are bent into a half moon or quarter moon shape, are used on the mineral processing equipment MechProTech designs and manufactures.

The bearings run on an oil film, so there is no surface contact between the bearing and the outside support for the mills and the scrubbers, and, as a result, there is no energy-consuming and grinding friction during operation, according to MechProTech Sales Manager, Wynand Boshoff.

“Vesconite is a sacrificial bearing that provides support. If the oil that the bearing runs on breaks down, there is no damage to our equipment,” he says.

The advantages of using vesconite also extend to cost, operations and logistics.

MechProTech noted that the hydrodynamic bearings are less expensive in this application than white metal bearings, which can be six times more expensive than the thermopolymer bearings, and are also hard wearing and grease free, requiring little maintenance in an industry in which machinery downtime can be costly.

NRW Holdings signs A$10 million deal to buy RCR’s Mining and Heat Treatment businesses

NRW Holdings has entered into an agreement to acquire RCR Tomlinson’s Mining and Heat Treatment businesses for A$10 million ($7.3 million) in cash.

The agreement was signed with RCR’s administrators, which have been offloading various RCR subsidiaries since shortly after the company declared total liabilities of A$581.3 million alongside cash and equivalents of A$89.9 million in its 2018 financial year.

The purchase consideration will be funded from NRW’s existing cash reserves, with the deal expected to complete within the next two weeks, NRW said.

RCR Mining and Heat Treatment form part of the original RCR Tomlinson business established over 100 years ago.

RCR Mining includes the Mining Technologies business, which owns significant intellectual property across a range of products and processes and is recognised as a market leader by global resources clients, according to NRW.

“The Mining Technologies business is a leading national and international original equipment manufacturer and innovative materials handling designer with an extensive product range including apron and belt feeders, high capacity conveyors, slide gates, stackers, spreaders, fully track-mounted in-pit mining units (an example pictured above), sizers, scrubbers and screening plants,” NRW said.

One of RCR’s recent mining technology innovations is a 5 km relocatable conveyor, which includes a semi-mobile primary crushing station and feeds directly into Fortescue Metals’ Cloudbreak iron ore processing facility in the Pilbara of Western Australia.

Both the Mining Technologies and Heat treatment businesses have a high proportion of activity in equipment product support and maintenance (both on site and off site), NRW said, adding that the Heat Treatment business has facilities that include the largest stress relieving furnace in Australia.

Mining Technologies and Heat Treatment generated around A$110 million of revenue in the 2018 financial year and have a track record of delivering positive earnings, NRW noted, explaining the acquisition would be earnings per share accretive on a full-year basis, excluding integration and other one-off costs.

Jules Pemberton, NRW’s Managing Director and Chief Executive Officer, said the acquisition would allow NRW to provide incremental services, in line with its strategic objectives, to several core clients common to both NRW and the RCR businesses.

“In addition, the annuity style income from the maintenance activities of Mining Technologies and Heat Treatment will provide a platform to continue to build a broader service offering across an expanded resources and oil and gas client base.”