Get More For Less

Weir Minerals is focused on mining safely, sustainably, smarter, and more efficiently. It is not that production is any less important than it has always been; rather, by looking at processes holistically and taking time to plan, test and implement well-designed flowsheets, the company believes that it can help miners produce more for less.

Process-focused

In many instances, this requires a willingness to think differently – to be less fixated on the outcome and more focused on how to get there. Take, for instance, valves. Compared to a lot of other mining equipment, valves are lower cost, haver a shorter lead time, and, for that reason, operators often under appreciate their value.

Yet, valves enable operators to isolate and shutdown other equipment safely, preventing small problems from becoming plant-wide disasters – they are key to safe and reliable operation. However, because they are often only installed as an afterthought, poorly selected valves can end up shutting down operations instead of keeping the plant running.

Weir Minerals recently expanded its range of valves with the Isogate® WR knife gate valve. Drawing on decades of wear analysis, Weir Minerals’ engineers have optimised its body design by reinforcing the areas subjected to the harshest wear and pressure, while reducing the weight elsewhere to produce a robust, long-lasting mining valve that is significantly lighter than comparable products.

The gate has also been redesigned with stronger materials, resulting in a thinner gate that can still withstand

John McNulty, Weir Minerals,

Australia, reviews how pumps and valves can help mining customers produce more for less.

the pressure of mining slurries. This combines with the valve’s unique gate guide, reducing deflection by ensuring smooth gate movement and less stress on the sleeve elastomer during blade transition.

The Isogate WR knife gate valve utilises Weir Minerals’ new Isogate WSL sleeve, which uses the proprietary Linard® HD 60 silica-reinforced natural rubber to solve the three most common problems with sleeved knife gate valves: leakage during cycling, tearing, and load distribution ring (LDR) failure due to corrosion and erosion.

Leveraging the Linard HD 60 rubber’s high resilience against cut, tear and abrasive wear to improve wear life, the new Isogate WSL sleeve fully encloses the LDR to prevent corrosion. By allowing the rubber to move with the blade cycles, the design reduces the chance of tearing while reducing slurry discharge by up to 75%.

But valves are only one piece of the puzzle, and this same commitment to innovate engineering underpins Weir Minerals’ approach more generally, including pump and pipeline design.

Pumping efficiently reduces costs

The amount of energy a pumping installation consumes depends on the pump efficiency, the drive train losses and the motor and/or motor controller electrical efficiency. Pump efficiency is the biggest determinant of power costs. A slurry pump’s efficiency is reduced by the presence of solids, and an efficiency ratio (ER) is used to correct the published water performance curve; pump design also has an influence on the ER. The Warman® MCR® rubber-lined slurry pump features a large-diameter, low-speed, high-efficiency impeller, which reduces energy consumption.

Weir Minerals’ team of slurry pump experts work closely with operators to provide guidance on how to improve efficiency depending on their specific application. For example, at flow rates less than 60% of the standard impeller best efficiency point, utilising a reduced-eye impeller and low-flow volute will improve pump efficiency. And where pumps may be prone to cavitation, operators should consider maximising the use of low-NPSH-style impellers. Pump and component selection helps reduce wear, which, in turn, minimises additional maintenance expenses.

By extending wear life, operators can significantly lower the total cost of ownership (TCO); the Warman MCR slurry pump has a number of innovative features that have been designed with this in mind.

For instance, it features patented shrouds that extend past the periphery of the pumping vane and expelling vane, providing improved flow and reduced wear at the expelling vane tips. Its large, open internal passages reduce internal velocities and, thus, reduce wear.

Nevertheless, pump performance is not just about the equipment – close collaboration between miners and original equipment manufactures (OEMs) is an often overlooked factor.

Figure 1. Weir Minerals Synertrex®-enabled Warman MCR 550 pump on site at Evolution Mining's Cowal Gold Operation, where wear life improved by 140%.

Figure 2. Weir Minerals’ Warman MCR 550 installed in a copper mine.

A solutions-focused approach

Case study: Australia

Weir Minerals understands that no two operations are the same, so it works closely with its customers to develop tailored solutions based on their specific requirements and conditions. Evolution Mining’s Cowal Gold Operations in New South Wales, Australia, wanted to increase production and reach a service life of 24 weeks uninterrupted production to align with major shutdowns and other equipment on site.

The Weir Minerals team installed a Warman MCR pump with R55® rubber liners, A65 full face adjustment throatbush and A61 impeller. Because of power limitations from the existing motors on site, they used rapid pattern prototyping to manufacture a custom 82% trimmed impeller for the application. The team also 3D scanned the site to ensure a trouble-free installation and finalised the custom design of connected Linatex® pipework, new cyclone feed line, and Isogate valves.

Cowal Gold Operations increased production and extended the pump’s wear life; the incumbent pump’s 12 weeks of continuous operation was significantly improved upon by the Warman MCR 550 pump, which achieved 29 weeks. Over one year, the incumbent pump’s TCO was AUS$2.2 million compared with the Warman MCR 550 pump’s AUS$1.7 million – saving Cowal Gold Operations nearly half a million dollars.

Regional factors

Operating costs often vary depending on where the mine and pump installation is located; local climatic and regulatory conditions have to be factored in when working out the TCO. The cost of water, for instance, varies greatly across regions.

The costs associated with the use of water to flush the gland of a slurry pump can be split into two components: the supply cost and the removal cost. The former depends on the type of pump – its size and gland type – while the latter depends on the particular process and commodity being handled.

The amount of water consumed by the pump depends on the type of seal. The mechanical seal and expeller or centrifugal seal can be operated without any water injection, but sometimes use small amounts to help reduce wear in particularly erosive duties.

The Warman MCR pump has a low flow design stuffing box that is also able to be centred. The adjustable stuffing box allows for centring of the stuffing box and lantern restrictor to the shaft sleeve, which increases packing life and decreases gland seal water consumption.

The Warman MCR slurry pump’s low flow stuffing box is made with tungsten-carbide-coated J221 shaft sleeves. The stuffing box also features close clearance split lantern restrictors with a harder non-galling coated inside diameter. The upgraded materials and design reduce gland water consumption.

The actual consumption of water also needs to be factored in. In remote areas, the supply of suitable gland water may be very costly due to the need for sinking bores and the long-distance pipeline pumping. Even when more readily available from mains supply, water can be relatively expensive to purchase in large quantities.

Case study: Latin America

At a Latin American iron ore mine, the operator wanted to increase its energy savings in all their processes, focusing particularly on reducing the consumption of process water. It had Warman MCR 250 pumps installed in one of its mills to transport slurry from the mill discharge to the hydrocyclone cluster. The installed Warman pump seals were wet seals with an average life of 3200 hrs.

Weir Minerals suggested trialling a Warman mechanical seal on the Warman MCR 250 pump; the mechanical seal requires a small amount of water to be injected to assist with lubrication and cooling of surfaces.

At the conclusion of the successful trial period, the time between maintenance intervals tripled and the customer’s water consumption costs decreased by 65% with the mechanical seal.

The importance of being close to customers

Inventory costs are something of balancing act. On the one hand, holding stock ties up capital that could

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otherwise be spent on revenue-earning activity; on the other, having stock on hand ensures spare parts are available immediately in the case of an unplanned shutdown or to ensure supply in the case of extended lead times.

Weir Minerals’ team of slurry pump experts works closely with mining customers to understand their equipment’s wear performance, maintenance schedules, and inventory requirements. It has a global network of service centres in all major mining regions to support its customers with all their inventory needs.

Case study: USA

Capstone Pinto Valley Copper Mine has two spare Warman MCR pumps; when a pump needs to be repaired, it is pulled out of the line and shipped to the Tucson Service Centre. Here, Weir Minerals service technicians pull it apart, laser scan it to determine where the wear locations are, provide a wear report and recommendations, and put it back together according to OEM specifications. Weir Minerals then ships the pump back to Pinto Valley within 5 – 7 days. This reduces downtime, saves Capstone Pinto Valley money by removing the need for a full inventory of spares to be kept, and frees up its maintenance staff to carry out work on other equipment.

Case study: Australia

Reducing spare parts consumption can significantly lower the TCO. At an Australian gold mine, for instance, Weir Minerals configured all their Warman MCR 550 pumps with composite throatbushes comprising half alloy and half rubber to address the localised recirculation wear around the eye of the throatbush. This resulted in a significant increase in the length of the Warman MCR pump life cycle.

This increase has reduced shutdowns from four per year down to a maximum of two per year, depending on tonnage throughput. This, in turn, has allowed the site to modify the maintenance plan and contributed to a reduction in spare parts consumption, which has saved the customer over AUS$2.1 million, while also increasing plant operation time.

As wear monitoring improves, so too will pumping efficiency.

Figure 3. Weir Minerals Isogate WR Knife Gate Valve from the factory.

Mining smarter

Weir Minerals wants to go beyond the traditional role of OEMs and become a digital end-to-end solutions provider to its customers. One important development in the realisation of this vision is the recent launch of Synertrex® IntelliWearTM digital wear monitoring system for spools and hoses in slurry pipelines.

The system is comprised of a digital sensor integrated into Weir Minerals’ Linatex and Vulco® hoses and spools. A central control panel captures information in a single location and a dashboard allows for visualisation and analysis of the equipment data via the Synertrex digital ecosystem. Digitalisation enables Weir Minerals’ customers to continue their normal operational duties, while large amounts of data are automatically analysed and interpreted in the background, via the Synertrex intelligent platform.

A conductive wire is installed in the rubber lining at various levels of thickness. As the lining wears, it activates sensors to indicate the extent to which the rubber liner has been worn and, in turn, how much life is left. An easy-to-use traffic light system has been developed which enables quick visual identification of the condition of the hose or spool. Less than 50% wear is green, between 50% and 70% wear is yellow, and greater than 75% wear is red – indicating it is time for preventative maintenance. The conductive wire is installed along the entire Linatex or Vulco spool or hose, throughout its diameter.

The central monitoring panel collects data from the sensors in the field and sends it to the Synertrex intelligent platform, which can then be viewed by operators and maintenance personnel. Information collected can also be uploaded to the cloud to be viewed on a live dashboard, which is automatically updated every two minutes. The intelligent system enables operators to view real-time wear information from any device remotely – ensuring continual monitoring and better control over their equipment.

Plant optimisation

With declining ore grades and increased regulatory pressure, miners have to increasingly rely on plant optimisation if they are going to meet the growing demand for many minerals. As a trusted OEM partner, Weir Minerals tries to understand each site’s specific challenges and develop bespoke solutions. It is something that is only possible because the company has a portfolio of products across the entire flowsheet, as well as the expertise to support them.

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