April 24, 2023 | 6 minute read
In mining environments, products must be able to withstand extreme conditions. Maintaining or improving reliability and water reduction becomes a real concern in these environments. Mines use large volumes of water, harsh chemicals and gases for processing materials. They move coarse materials and thick slurries containing a high concentration of abrasives and particulate that are damaging to pumps.
John Crane is dismissing the myth that seals are not designed or tough enough for the mining industry. Mechanical seals were traditionally not the preferred method of pump sealing in the mining industry, but we now have engineered component and standard cartridge seals with robust parts made specifically to suit harsh mining applications—manufactured from abrasion-resistant materials, for example, duplex, super duplex and 27% nickel chrome.
In mining operations around the world, there are multiple options for sealing slurry pumps. Geographical location and economic and environmental issues play a key role in which option is chosen. Packing remains the go-to solution for sealing slurry pumps, which both the pump OEMs and mine operations embrace. With that said, today, mine operators are able to choose from third-generation packing technology and engineered heavy-duty single and double slurry seals. Mechanical seal designs offered today are constantly evolving to meet the economic and environmental issues mine operators face. Making the transition from packing to mechanical seals allows for improved reliability and lower maintenance needs since mechanical seals don’t require maintenance once installed.
For the harsh and difficult environment of slurry applications, John Crane’s range of rugged slurry seals are designed to resist the destructive effects of ores, limestones, phosphates, kaolin clay, lime mud, rock salt, sludge, sand and gravel.
Slurry seals have been designed to work continually in hostile environments, like mines. John Crane has a line of slurry seals to provide cost-effective solutions that dramatically increase mean time between repair (MTBR), reduce energy consumption and increase the efficiency of critical equipment. John Crane’s line of slurry seals, known for their slurry sealing reliability in mining and minerals, include the following:
- Type 5840: Designed for the rigorous duties associated with general mining processes, the 5840 uses a robust primary ring design and secondary sealing elements, making it the perfect general-purpose seal for slurry applications
- Type 5860: Designed to operate in the harshest abrasive slurry environments such as underflow, pumps, tailings pumps, mill circuit pumps and cyclone feed and discharge pumps.
The benefits of a slurry seal include, but are not limited to:
- Robust design to support intermittent or batch operations when required
- Longer pump run times and lower operating costs than pumps with packed glands
- Engineered for reliability, sustainability, and reduced cost of ownership
- Water savings due to the ability to operate with reduced or no flush
The driving force behind upgrading from packing to mechanical seals is the need to increase the reliability of rotating equipment. Packed pumps are prone to high shaft wear and excessive leakage which results in premature bearing failure, ultimately leading to high maintenance costs and a reduction in MTBF. This has seen the introduction of engineered slurry seals e.g., our Type 5840 single slurry seal, which can be installed in applications with little to no flush.
The single biggest sealing technology option available to the mining industry to improve pump reliability and bottom line is to upgrade to mechanical seals on the pumps that are critical to operations and require high levels of maintenance. Filter feed and tailings pumps are typical examples. By transitioning from gland packing to mechanical seals, mining operations have been able to do away with daily and weekly maintenance schedules on tailing lines and run uninterrupted for 12-18 months or even enjoy multi-year runs on the filter feeds. This results in significant maintenance cost savings, reduced equipment downtime and potential water savings—in some cases customers can save 120 L/min (31.70 Gal/min) per pump.ESG Goals
Face treatments are suited to assist our customers’ Environmental, Social and Governance (ESG) goals, offering a water reduction or elimination solution. Mining and mineral processing operations often have high water footprints, as many stages require the use of water. So, one of our biggest mining concerns is water saving. Besides saving water, another key worry of mining operations is energy efficiency. Upgrading from packing to mechanical seals with less friction, saves and reduces energy consumption in the motor.
Water conservation and reduction of wastewater and reducing energy usage are key areas where new sealing technology can help. New sealing technology, like reduced flush design and upstream pumping (USP), has been used successfully to reach these ESG goals. John Crane Diamond® generates less heat, reducing the need for cooling water and, due to its low friction, also reduces energy loss. USP eliminates seal face flush to dissipate seal heat, reducing water usage.
The need to reduce water consumption in a mining operation goes beyond the societal benefits. Poorly managed groundwater can destroy the viability of a mine and cause an unsafe working environment. The large volume of water being pumped requires a major capital expense making it an important economic issue. John Crane has developed products, like the slurry seals, USP and John Crane Diamond face treatments, that support our customer’s efforts by minimizing leakage and saving labor costs.
A typical mine would see anything from 60-120 liters (15.85-31.70 gallons) of water being used per minute, per pump, as gland service water, to gain optimal life out of entry-level packings. Upgrading from packing to mechanical seals meets the needs of in-country environmental regulations, such as energy reduction and water consumption/reduction.
Contact us to learn more about John Crane’s slurry seals and how to extend MTBR.