Tag Archives: Weir Minerals Africa

Weir Minerals enhances pump maintenance with adjustment technology

With a longstanding reputation for engineering expertise, Weir Minerals continually develops solutions and technology to better serve the mining industry. Recognising that throatbush wear rate has a major impact in the overall efficiency of slurry pumps, Weir Minerals has developed superior rotating and axial adjustment technology.
In many applications, the pump’s throatbush is the component that has the shortest life compared to the impeller and liners, with considerable variability.
Adjusting the gap between the throatbush and the impeller front shroud reduces hydraulic recirculation in the pump. This prevents localised wear on the throatbush, improves hydraulic efficiency and lowers the total ownership cost for the operator. To avoid impacting the plant’s production, these adjustments are often performed while the pump is operating. However, this can have safety implications for individuals working at the front of the pump unit.
“Manually adjusting an alloy throatbush on a large pump requires several people and is labour intensive. It requires mechanical tools to adjust the four pusher bolts, one at a time, in order to reduce the gap between the throatbush and impeller. We wanted to find a safer and quicker way to extend the wear life of the pump with regular adjustments, which led us to development of this technology,” states Marcus Lane, Global Product Manager for Centrifugal Pumps for Weir Minerals.
“Our automated throatbush adjustment solutions are available for pumps fitted with either rubber or alloy throatbushes on Warman slurry pumps used in the most arduous applications, and have been designed with our customers’ safety and pump operation in mind. By mechanising the adjustment procedure, personnel are removed from the line of fire, and the accuracy of axial movement is increased,” states Ron Bourgeois, Director of Slurry Pumping Technology Group for Weir Minerals.
Weir Minerals’ automated adjustment systems speed up the process, allowing for more frequent adjustments with minimal effort. When maintaining an alloy throatbush, all four bolts are adjusted at the same time to ensure even adjustment and accurate positioning, improving the wear life of the throatbush.
Rubber throatbush adjustment is considerably different because it poses the risk of hysteresis and premature failure of the throatbush. The goal is not to adjust to a minimum clearance but to maintain a standard gap to ensure that there is no contact between the impeller and throatbush, whilst periodically rotating the throatbush face to avoid acceleration of localised wear.
“We developed an automated rotating solution which maintains an optimum gap between the throatbush and impeller front shroud for the particles to flow through without catching and tearing the rubber. The localised surface wear is usually near the discharge position, but by slowly rotating the throatbush, we even out the material loss over the entire face. Field results have been very positive, showing an average of 40% increase in wear life,” states Claudio Needham, Application Engineer for Weir Minerals.
For the smaller Warman® slurry pumps used in medium to heavy duty applications, Weir Minerals offers a single point adjustment mechanism, providing both axial and rotational repositioning. This allows one individual to safely stand to the side of the pump while making the adjustment.
Mining operators who have trialled Weir’s adjustment technology have reported improved wear life and safer, simpler maintenance through the process of regular adjustment.
Weir Minerals has already taken its adjustment technology one step further by integrating it with their IIoT Synertrex® platform to offer predictive maintenance feedback.
“This is made possible through machine learning. Over time Synertrex learns from past adjustments, recording how many times the throatbush was adjusted and the magnitude of adjustment each time. This trending data is collected and analysed by Synertrex to communicate future adjustment requirements. Through automating all adjustments, we can successfully communicate remaining useful life, and inform customers of optimum times to adjust the pump to increase efficiency and maximise wear life,” Marcus Lane concludes.

WEIR MINERAL’S CAVEX® HYRDOCYCLONE SHINES IN DIAMONDS

The successful performance of Weir Minerals’ Cavex® hydrocyclones at a diamond mine in South Africa’s Northern Cape Province has proved the technology’s applicability in dense medium separation (DMS) plants treating diamondiferous material.

In her presentation to the Southern African Institute of Mining and Metallurgy (SAIMM) diamond conference in Johannesburg in 2018, Weir Minerals Africa’s Senior Process Engineer, Boitumelo Zimba, said the hydrocyclones improved plant efficiencies and produced 40% more tonnage than the mine’s target.

“As the Cavex hydrocyclone is tried and tested in hard rock mining and coal classification, the Cavex 360° laminar spiral inlet profile was used as a basis for the development of a dense medium cyclone,” Zimba said. “Individual casting patterns were developed and produced in order to fabricate the Cavex dense medium hard chrome cyclone with the exact laminar spiral feed chamber that exists when moulded out of rubber.”

The customer required a solution that could offer at least six months wear-life, and a probable error of separation (Ep) of no greater than 0,08 at a cut density of 3,1 tonnes per cubic metre (t/m3). Tracer tests were used to monitor the efficiency of the separation achieved by the Cavex® hydrocyclones to ensure all of these requirements were met.

“Ep values achieved were 0,042 for the 4 mm tracer tests and 0,035 for the 8 mm tracer tests, which were below the set maximum target of 0,08 from the mine,” Zimba said. “This highlighted the benefits and improved efficiencies of the Cavex laminar spiral feed inlet.”

The lower the Ep – or probable error of separation – the more efficient the separation; it is defined as half the difference between the density at which 75% is recovered to sinks, and that at which 25% is recovered to sinks.

“The customer’s tracer tests on the Cavex hydrocyclones showed that cut points of 3,08 t/m3 were achieved for both the 4 mm and 8 mm tracers,” Zimba said. “This was within the performance levels of 3,1 t/m3 that the customer had specified.”

Initially, the hydrocyclones were commissioned to treat only fines at the diamond plant – the minus 8+1 mm material. Later however, the mine decided to run a combined DMS, after which the full DMS size range of minus 20+1 mm was treated through all the fines DMS hydrocyclones.

The unique design of the laminar spiral inlet geometry delivers sharper separation and maximises capacity while delivering a longer wear-life than conventional involute or tangential feed inlet designs. By providing a natural flow path into the hydrocyclone body the design allows the feed stream to blend smoothly with the rotating slurry inside the chamber, reducing turbulence and improving separation efficiency.

“Combining our cone and spigot components in the hard metal range is an important contribution to the reduction in turbulence,” Zimba explained. “Another vital factor is the Cavex inlet design with 360 degree scroll; this design was proven through extensive computational fluid dynamics (CFD) analysis as well as our multiple installations to date.”

Weir Minerals also conducts ongoing research and development on methods to minimise turbulence on assembled casted components. The Cavex® hydrocyclones are designed with a variety of inlet sizes to accommodate a wide top size at specified medium-to-ore ratios. The inlet sizes range from 0,2 to 0,33 as a function of the hydrocyclone diameter.

The Cavex® CVX hydrocyclone also has a wide range of vortex finder sizes to maintain separation efficiency at different operating yields and spigot sizes. The vortex finder sizes range from 0,4 to 0,5 as a function of cyclone diameter, and are designed to maintain a strong air-core at different spigot sizes.

To prolong life and efficiency, the hydrocyclones can also be manufactured with different materials. Cavex® CVXA hydrocyclones are hard-wearing and are cast in 27% chromium iron for maximum abrasion resistance; components are designed for ease of maintenance, with all surfaces joined with a layer of epoxy cement.

“Our focus on supplying best-in-class technology includes developing components that offer low wear rates,” said Zimba. “This is achieved by using a combination of materials with different wear rates in a range of hydrocyclone parts. This is made possible by our global technological expertise that allows us to cast components using various alloys, depending on the type and abrasiveness of the ore being treated.”

Weir Minerals Africa operates two foundries in South Africa – one at its Isando facility and the other at its Heavy Bay Foundry in Port Elizabeth. This allows the organisation to cast items in-house leveraging its local foundry personnel’s knowledge, experience and expertise, ensuring that the highest standards are maintained.

This approach ensures optimal life of the hydrocyclone in operation, and reduced maintenance costs by replacing worn parts in situ. It also eliminates the risk of any adverse effects on performance arising from mixing old and new hydrocyclone components. Further, safety on site is enhanced by minimising the maintenance work necessary on the installed hydrocyclones.

“Future work will include the investigation of various alloys to combat high wear rates on some of the hydrocyclone components, in particular the vortex finder and the cone sections,” Zimba said. “This will allow longer operation and plant stability.”

WARMAN® MILL CIRCUIT PUMPS REDUCE OPERATING COSTS

Engineered for use in the most aggressive duties, Warman® Mill Circuit pumps easily manage large size particles in highly abrasive slurries. These pumps are designed for the most severe slurry applications such as ball and SAG mill cyclone feed as well as water-flush crushing in mineral processing plants.

Weir Minerals Africa is showcasing its flagship mill circuit pump – the Warman® MCR®450 at Electra Mining Africa 2018.

Marnus Koorts, Product Manager – slurry pumps at Weir Minerals Africa, says “customers will be able to see this massive pump with its 1.5 metre diameter. Like all pumps in the Warman® MCR® range, this 13 ton slurry handling machine is designed to increase productivity and decrease downtime, compared to older generation and other pumps in the industry”.

Koorts says that the Warman® Mill Circuit pumps are based on 80 years of fundamental and applied research, backed by wear performance field trials.

“Mill circuit applications are among the toughest in a minerals processing plant, and the Warman® MCR® pumps incorporate the latest in hypereutectic alloy and elastomer technology,” he says. “This significantly extends the wear life of the pump in highly abrasive and corrosive slurries, reducing operational costs.”

The high resilience rubber wear liner enables the handling of coarse particles and ball scats with ease, while its lightweight design relative to other pumps in its category facilitates safer handling. It is also a lower cost than traditional heavy metal liners.

Importantly, different material combinations are available to ensure that the customer gets a fit-for-application pump capable of providing reliable performance cost effectively, tailored to their site conditions.

The Warman® MCR® pump has a large diameter, low speed, high efficiency impeller. Koorts explains that this can be manufactured from a range of abrasion resistant alloys allowing the most appropriate material to be selected for the customer application. This will increase wear life and reduce operating costs when compared to other pumps in its category.

Reduced recirculation is achieved by the deep expelling vanes on the front of the high chrome alloy impellers. Expelling vane tip turbulence is minimised by the patented shroud feature that traps tip vortices and prevents localised scouring on the throatbush face. This, again, extends wear life and reduces maintenance.

The split outer casing on the Warman® MCR® pump provides structural integrity and high operating pressure capability, ease of maintenance and safety. This feature also allows internal liners to be fully worn before replacement.

Warman® throatbushes feature pre-swirl vanes which offer optimum reliability and wear life. There is a patent pending on this innovative throatbush design which was developed to improve impeller eye wear life and reduce the wear caused by recirculation at the impeller-throatbush interface. This has been accomplished by a series of guide vanes in the pump inlet which induce a rotational velocity in the slurry.

An adjustable stuffing box allows for the centering of the stuffing box and lantern restrictor to the shaft sleeve. This increases packing life and decreases gland seal water consumption.

Another new design feature is the single-point gland adjustment which facilitates safe packing adjustment outside of the stuffing box guard while the pump is operating.

“Our Warman® Mill Circuit pumps are engineered to offer the most cost effective solution across a range of applications, and with installations on many leading mine sites across the globe it is proven to be the mill circuit pump of choice for the hard rock mining industry,” Koorts concludes.

THE MILL LINER THAT LASTS LONGER

Fields results show that the new Vulco® R67 mill lining rubber compound from Weir Minerals delivers an increase in wear life of 20%.

With a liner that can run significantly longer, operators will experience a measurable reduction in mill downtime, installation and maintenance costs.

“This is a breakthrough in the industry; a rubber mill liner that in extensive global trials delivered on average 20% longer life than comparable composite lifter bars. This means less shut-down time for maintenance, which in this highly competitive environment represents a measurable outcome to our customers’ productivity and bottom line,” states Mathias Kuhrke, Global Product Manager for Mill Lining Systems at Weir Minerals.

The innovative premium rubber compound is the most wear resistant Weir Minerals has ever formulated. Operators using R67 lifter bars within their mill will not only benefit from the increase in wear life, but they will notice a measurable reduction in installation and maintenance costs as a result of a longer run schedule.

The making of R67 compound
Weir Minerals is an industry leader in materials technology and have been supplying the Vulco® R63 rubber compound to mill lining applications across the globe for over 50 years. Whilst this technology performs well in most grinding applications, many suppliers are perceived by the market to offer similar rubber compounds with no real differentiation. Weir Minerals identified a clear gap in the market for a rubber compound that could increase the wear life of its mill liners and outlast the rest.

After extensive field research on the current rubber compounds available to the market, Weir Minerals expert engineers and material scientists developed the unique patented material that forms the R67 compound.
“Using our extensive in-house knowledge, experience and expertise, we were able to develop a new Weir proprietary elastomer that is able to withstand the severe abrasion typical in mill systems applications. Our Vulco R67 compound utilises new technology and chemistry in elastomer formulary which overcomes the limitations of more traditional elastomer compounds used in the market today,” states Dr. Michael Lum, Materials and Elastomer Development Manager for Weir Minerals.

The Vulco® R67 rubber compound is visually different from others in the market place, with green capped ends on the lifter bars.

“During the product development process we added a green pigmentation to the formulation to visually set our lifter bars apart from the competitors. Now when a mill operator sees the distinct green strip on the lifter bar, they will know they have a premium product,” says Lum.

What customers think
Over 10 trials spanning four continents have shown significant wear life improvements, in some cases exceeding a 50% increase in wear life! Weir Minerals are confident the latest R67 rubber technology will help operators across the globe get the most out of their mill.

“Our customers were at the heart of this new compound development and we worked closely with them throughout the field trials. During this time, we encouraged them to provide honest feedback on the R67 rubber compound. There’s tremendous value in having a trial partner that documents the downsides as well as the positive benefits. This allowed us to note which applications the new compound is best suited for, or make further improvements to the compound,” states Hayden McLean, Mill Lining Product Manager for Weir Minerals.

One operation to reap the benefits of the premium R67 rubber compound is Simplot Phosphates, LLC. Operating a phosphate mine, north of Vernal, Utah, this long-standing customer of Weir Minerals agreed to trial the liner with R67 rubber. After a nine-month trial, the liner achieved a 29% improvement in wear life and had 20% service life remaining when it was removed. The trial also achieved an estimated 25% reduction in maintenance and reline costs.

Bart Smuin, Mill Maintenance Supervisor for Simplot states: “R67 lasts longer, which delivers less downtime and less time in the mill. That is the biggest advantage.”

Weir Minerals’ new Vulco® R67 premium rubber compound sets the benchmark for mill liners worldwide. Contact your local Weir Minerals representative to find out how the Vulco® R67 rubber compound can keep your mill running at capacity for longer.

WEIR MINERALS AFRICA SHOWCASES END-TO-END SOLUTIONS

Visitors to this year’s Electra Mining Africa exhibition at Nasrec will be in for a feast of technology at the Weir Minerals Africa stand; particularly hard to miss will be their 7 metre high crushing station featuring a high performance Trio® cone crusher.

“We are reminding visitors and customers that Weir Minerals Africa – well known for our pump technology – has transformed into an integrated solutions provider in minerals processing,” says Hoosen Essack, Process Manager at Weir Minerals Africa.

“With our extensive footprint across Africa, we are adding even more value through this growing range of offerings.
Underpinning our service levels is our process expertise that equips us to partner closely with customers in finding answers to their daily challenges.”

Among the other items on display will be a large Cavex® hydrocyclone with a substantial 1500 mm diameter and weighing five tonnes.

With the company’s leading position in pumping equipment, the stand will also display the impressive Waman® 450MCR pump, measuring 2,5 metres in diameter.

Essack highlights the strategic importance of the company’s process department, which is staffed with experts who work closely with customers on efficiency and other issues, whether on a particular item of equipment or an entire comminution circuit.

“This capacity allows us to provide enhanced support to customers on their plants, taking our role well beyond just supplying product,” he says. “This centralised team of experts are available to all of our branches, so customers can always be assured of skilled input on challenging problems and equipment choices.”

He emphasises the value of specialised tools employed by Weir Minerals, such as the JKSimMet software to simulate comminution and classification circuits, in helping customers select the appropriate solutions for their mineral processing plants.

“To consolidate our continuous improvement efforts and stay at the leading edge of technology development, research and development is a strong focus for Weir Minerals,” he says. “Weir Minerals as a leading global player also has centres of excellence around the world to each focus on each particular field.
While South Africa focuses on screen performance, for instance, the United States focuses on comminution equipment and centrifugal pumps.”

WEIR PUSHES COMPOSITE LINER DESIGN TO IMPROVE MILL LIFE, PERFORMANCE

In the latest addition to its Vulco® composite range of mill lining systems, Weir Minerals Africa has introduced a new heavy-duty lifter bar to optimise service life and further contribute to lowering customers’ cost of mill ownership.

“The design and strength of this innovation makes us confident it will compete well against steel liners,” says Kevin Sherwen-Slater, Vulco Product Manager at Weir Minerals Africa. “It will also allow us to approach the bigger mills, in the size range of 6,5 metre diameter up to even 10 to 11 metre diameter.”

He notes that many process plants in the global mining sector are starting to ramp up production in response to higher commodity prices, putting them in a better position to benefit from more advanced liner technologies that offer longer life and less downtime. New mills being built tend to be larger, single-stream units that run at high tonnages for better efficiencies and throughput; as a result, mill uptime and lifespan have become more important factors in mine profitability.

“It is therefore increasingly imperative that mills run continuously, reliably and efficiently,” he says. “These new liner technologies – with stronger compounds and better designs – contribute significantly to mines’ efforts to achieve this.”

Manufactured with the new R67 rubber compound, which boasts higher wearing resistance than compound R63, the heavy-duty lifter also incorporates Hardox 500 steel to resist wear.

Vulco® composite liners have become popular for several reasons, says Sherwen-Slater, including a power consumption saving of 25% to drive the mill compared to steel lined mills, throughput increases of some 27% on grate discharge mills due to minimum blinding of the apertures on the grates and service life improvements of 30% compared to steel lined mills in certain applications.

“There is also a mill noise reduction of about 9 dB due to sound deadening from the rubber material, which is an important consideration for many mines as they work towards lower noise levels as part of improving mine health and safety,” he says.

The reduction of material lockup between the liners and the mill body, due to compression fit on installation, is a great benefit for low grade plant operations and reduces the risk of theft during liner replacement.

The liners – which are only two-thirds of the weight of steel liners – allow for a reduced installation time due to ease of handling, thereby cutting downtime and supporting plant productivity efforts. An added advantage is that the bearing loads applied by the mill itself are substantially less with composite liners.

“Due to the weight difference, a mill’s weight could be increased by 400 tonnes with the addition of steel liners, whereas the equivalent weight with composites would be less than 300 tonnes,” he says. “This represents a notable reduction in the pressure on the bearings, in turn improving their lifespan and reducing maintenance costs.”