What’s Next for Slurry Pumps?

The next generation will likely be bigger, smarter, tougher and ‘connected’

By Russell A. Carter, Contributing Editor

Slurry pumps are the heavyweight contenders of fluid transfer, with the largest models capable of moving thousands of gallons per hour of water/solids mixtures that can be viscous, abrasive, corrosive — or all of the above. They’re bigger and a step or two slower than their water-pump stablemates, and although “large” is often associated with “expensive,” larger also can mean better: As pump supplier KSB Mining noted, larger pumps can benefit mine operators in multiple ways: They rotate more slowly, providing longer wear lives, and therefore can extend routine maintenance intervals. Operators can also benefit by needing fewer spare parts on hand, and maintenance staff has less equipment to manage.

However, the fact remains that they’re not cheap to buy and operate, their size can make repairs and relocation more difficult — and there’s nothing on the process-technology radar screen right now that offers wholesale elimination of slurries or the need to transport them efficiently and reliably, so slurry pumps will be part of the mine environment for the foreseeable future. That doesn’t mean their usage parameters will remain static or new opportunities for enhanced performance won’t emerge. E&MJ recently asked some of the sector’s leading suppliers to sketch out their vision of the next generation of slurry pumps, with particular focus on the role of pumps in the “connected” mine and on improvements in pump design and performance.

Jessy Parmer, business development manager for Xylem Industrial Solutions, expects incremental changes in some aspects of pump operations: “While the role of pumps within a mine setting will not necessarily change, how the pump is used and connected to other processes on-site will certainly evolve. As mines become more technically advanced, so do pumps. Smart mine water management technologies are sparking inspiring visions of the future and bringing concepts like the world’s first autonomous, people-free mine ever closer. For example, a team of Xylem engineers and designers are working closely with New Boliden’s Renström mine in Sweden on a pilot project as part of a process to introduce automation into the company’s mines.”

“Built-in intelligence” he continued, “is one means of pump transformation resulting in enhanced pump performance and efficiency, optimal power consumption, greater energy savings and reduced running costs. It also means better inventory management and reduced capital expenditure on a variety of spare parts. Built-in intelligence enables the pump to run at varying performance conditions, operating on a performance field rather than performance range (50%-125%).

“Remote visibility of pumping equipment is another game-changer. Today’s sophisticated pumping systems offer either built-in remote visibility or remote monitoring and control via an external system, allowing users to run their operations from afar. This greatly enhances site safety, particularly if sites are remote, and allows for smarter use of resources on-site, freeing up time that would otherwise be spent travelling to and from a pump station.”

Jeff Davis, western regional sales manager at Tsurumi Pump, pointed out that monitoring systems of various types and levels of sophistication have been around for more than a decade, and can be either external, such as SCADA systems, or internal systems that prove protection similar to a motor saver in that they shut the pump off if there is a fault such as low voltage/high amp draw, phase issues with the power source or within the motor itself, overheating, and locked rotor usually caused by clogging problems.

“Monitoring the system pressure on the discharge side of a pump will allow you to see where on the curve your pump is operating,” said Davis, “and when the pressure drops you can tell there is an issue, usually a worn impeller, which causes an opening of the tolerance between impeller and wear plate or just a drop in discharge rate. In that sense, there are several ways that the manufacturers as well as the installers can set up monitoring.

“The point is to catch the drop in performance early enough to plan a preventive maintenance intervention before catastrophic failure,” he said. “It allows the mine to run smoother without significant delays or shutdowns in production due to pump failures.”

Kenny Don, global product manager for FLSmidth’s Krebs pumps, cyclones and valves, can envisage significant improvements in pump maintenance and performance: “The possibilities are endless if you have the right expertise and historic data. As [pump] duty conditions are stabilized from the mine ramp-up phase, we can use advanced programming to predict the life of different components and drive ERP systems to order parts and maintenance activities. This could even include small components such as packing for events such as gland water line plugging. When that happens, the flow will drop significantly, and the system could alert maintenance to check the line and order new packing and a shaft sleeve.”

Asset Health: Access to Information

“Asset health monitoring systems are becoming more common on new innovative pumping systems and contribute greatly to production uptime,” Xylem’s Parmer noted. “Better asset visibility enables operators to easily assess when to service equipment, which minimizes downtime — crucial to successful mine operations.  It also reduces costs, as unplanned downtime can cost up to 10 times more than routine maintenance. Enhanced visibility also helps to ensure the pump is running as efficiently as possible. Remember, the greater the wear and tear on a pump, the harder it has to work to achieve optimal performance.”

Weir Minerals told E&MJ it believes the key to the success of connected mines rests on gaining access to multiple sources of information, an emphasis on smart data and a commitment to holistic intelligent platforms. The company noted that its slurry pumps are often the heart of the minerals processing circuit, and the unexpected breakdown of a single pump can have an enormous impact on operations. Moreover, running pumps at a suboptimal level results in both energy wastage and reduced component life. Weir Minerals said its Synertrex Intelligence Platform, driven by advanced digital technologies, improves equipment performance, abates emissions and reduces component wear.

Typically, Weir Minerals assumes that when operators talk about digitally optimizing a pump’s performance, they are referring to the application of a condition monitoring system to add a degree of predictability. For example, sensors may monitor impeller wear to ensure the component is replaced at the ideal time. Similarly, sensor data improves operational visibility and helps provide a better understanding of when, say, the gland seal requires maintenance adjustment. In addition to these sensors, condition monitoring technologies also typically include an IIoT gateway, which performs several critical functions from translating protocols to encrypting, processing, managing and filtering data, as well as a cloud-based analytics platform. These technologies are already well established in the mining industry and it’s not uncommon for them to be applied to slurry pumps.

But Weir Minerals maintains that these traditional condition monitoring solutions are only the starting point of what is achievable. “As an OEM, we work closely with our customers to ensure we’re a valued service partner; we have access to data that supports closing the loop between what’s achievable with the data collected from sensors and the additional data we have access to as the pump OEM and service provider,” said Ole Knudsen, digital director at Weir Minerals.

Knudsen explained that only Weir Minerals has access to Warman pump design data, maintenance histories and pump curves, which significantly enhances the Synertrex Intelligence Platform’s capabilities. By further expanding data sources — by having a service technician on-site to upload data related to physical observations, handheld measurements and changes related to wear parts — Weir Minerals is able to offer its customers a level of complexity and analytic detail well beyond what typical condition monitoring platforms can provide.

“The key here will be to add a holistic intelligence platform that gathers data from multiple data sources — from sensors to enterprise and service management systems — and bring them all together into a single digital ecosystem where collaborative actions can be performed and events put into perspective,” said Knudsen.

Having all this data and supporting information in a single environment is what drives the training of machine learning models, which in turn makes artificial intelligence possible through a series of neural networks, analysis of relational event dependencies and the probability of root causes. In turn, this drives automated and accurate decision support recommendations in which suggestions or prompts are provided to support human intervention. Other useful information, such as remaining useful life, through predicative analytics can be extracted and condition-based maintenance strategies can be implemented to drive overall equipment effectiveness (OEE). This is how process optimization becomes a dynamic tool.

Knudsen said Synertrex is moving toward the next stage, in which the connected mine will combine intelligent data from multiple equipment levels. For example, Warman slurry pumps intelligently and autonomously communicate with Cavex hydrocyclones to ensure ideal cyclone pressure for optimal separation and the highest recoveries at all times. “These will drive interactions between the equipment, advising on optimal conditions while still balancing the supply versus demand in order to satisfy the overall process. From this point, control philosophies can be developed, improved and implemented to automate the reaction on system generated recommendations with no human intervention required,” Knudsen said.

Solving the Application Puzzle

The industry’s prospects of larger pumps installed in increasingly remote, deep and difficult-to-access locations have prompted closer focus on how improved case and impeller metal alloys, basic design considerations and better selection of pump types and models for a given application can help ensure optimum pump performance under these conditions.

Performance is key when dealing with an expanding mine and a remote location, according to Xylem’s Parmer. “No miner wants an inefficient pump that needs to be replaced at a remote site,” he observed. “Once you’ve found a pump that fits the criteria in terms of power and footprint, ensuring that performance meets the required duty conditions is the final piece of the puzzle. Enabling the pump to operate as close to the duty condition as possible will greatly enhance production uptime.

A variety of problems can cause a pump to overheat, and “…there is increased attention on heat dissipation within slurry pumps,” Parmer said. “In many cases, pumps are moving media of a high viscosity, with a high percentage of solids, or both, that coupled with varying duty conditions can equate to greater strain on the pump leading to overheating. This directly relates to uptime and the overall efficiency of the equipment. As a result, internal cooling and exploring efficient ways to dissipate heat, especially around the stator housing, is a key focus for submersible pump designers.”

“Internal closed loop cooling systems are also important in dissipating heat quickly, especially when the pump is located remotely. In many instances, dry running becomes a problem. This can be prevented by having an intelligent pump in place or a system that can detect this or other issues, putting the pump into snore mode, reducing its speed, which in turn mitigates dry running risks and overheating.”

Regarding pump design and materials considerations, Parmer said both construction and seal faces of the pump are determined by the substance being pumped. “If the media is of a lower pH, then harder seal faces and material constructions such as duplex stainless steel or hard iron hold up better. When operating in deeper shafts, seal and bearing designs that reduce high temperature situations will greatly increase production uptime, keeping the pump in service longer.”

Building Better Pumps

Potential advances in pump construction materials could also play a role in quicker product development cycles and ultimate pump performance. For example, GIW Industries, a KSB subsidiary that markets a number of popular heavy- and severe-duty slurry pump product lines, recently commissioned a new R&D foundry to develop and test new materials for pump fabrication. The company said the new metallurgical facility includes a coreless induction melting system with three melting furnaces that can facilitate faster, more efficient alloy development at greater capacity. With this equipment in place, the lab, according to the company, can run multiple experiments on materials with tight control over chemical composition and thermal conditions, and can also mimic manufacturing conditions, cutting the transition time from R&D to production.

Material design advances should be coupled with innovative utilization opportunities to maximize value to the customer, according to Kenny Don. “Pump design is always evolving to increase safety, efficiency and wear life,” he said. “However, from a hydraulic perspective, there are few possibilities left that can provide incremental improvement. Most companies have turned to improved materials as their main solution, and while we are doing that too, we are also trying to come up with new ideas to automate maintenance and data analysis. Our customers are in the business of making copper or gold, for example, not in the business of maintaining pumps. Thus, often pumps are abused and not optimized, which if corrected, could have major power, spare parts and downtime savings. We just need to make it easier for customers to optimize.”

Tsurumi’s Jeff Davis agreed there are increasingly more pump models being designed with harder, more abrasive-
resistant wear parts and cast-iron pieces, but pointed out that these typically heavy-duty items can be expensive. An alternative to expensive high-chrome iron parts is to treat lighter parts with abrasion-resistant material that reduces the rate of wear on those parts. Periodic inspection enables a user to see if the coatings are nearing the end of their service life, ready for replacement with similarly treated spares.

“Although parts can be made harder or coated for resistance to abrasive particles,” he continued, “seal arrangements and electric motors are still vulnerable to wear or overheating in harsh applications. Thermal protection in the motors and oil baths for the seals are ways to prolong the life of the unit but eventually replacement is necessary. Slurry pump service and parts support from the manufacturers and distributors is critical in the mining industry because the cost of shutdown for emergency removal and replacement of pumps can be extremely high.

According to Davis, manufacturers and their distribution partners are increasing inventory in order to keep up with the industry’s high level of production. Exchange programs have become a popular model to provide quick response to necessary pump maintenance. These programs ensure the mine will have on-site replacement pumps and spare wear parts available for any emergencies. The manufacturer or distributor also keeps backup units on hand and periodically collects pumps needing service and delivers new or repaired pumps to replenish the on-site mine inventory.

In addition, noted Davis, the industry’s increasing need for training of service and operation personnel has motivated manufacturers and suppliers to offer more pump schools and service technician training to the mines. There is also a trend to have pump specialists on-site and on the payroll at the mine because pumps play such a key role in operations and production levels.

Planning for Top Performance

As more than one expert we talked to pointed out, any existing plant could probably benefit by adopting recent pump-related technologies and services to improve current performance, but the best time for plotting strategies to extract maximum value from pumping equipment is at the design stage. FLSmidth’s Don explained: “Too often pumps are sized for throughput years down the road, causing the pumps to prematurely fail due to low flow conditions. In other plants, they do not prepare for increased throughput, locking the pump size in place, especially with pumps using a direct drive arrangement. We work with our EPC and end user customers to map out their duty conditions for startup, midrange, and future tonnage levels. We can select motors, drives, and pump power frames that can handle different pump wet ends for those conditions. Wet ends can most easily be upgraded or downgraded with just a few changes in piping if the drive and power frame can handle it.

“Slurry pumps last the longest when they are operating for the flow and head ranges they were created to operate in, no matter what material you make them out of,” he added. “The way to make the biggest difference is by building in the flexibility to upgrade or downgrade the size of your pumps. We recognize that we can’t predict all future duty conditions, but if we at least gave it a shot when designing plants, customers would have the lowest cost of ownership and lowest power costs/carbon footprint when it comes to their pumping applications.”