Extend the mechanical seal life of your Centrifugal Slurry Pump

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Pumping slurry is one of the most demanding applications for any pump. Parts wear out, maintenance and repair costs are high. In many cases, frequent pump failures lead to costly production downtime. Also, excess sediment build-up in a sump cost time and money to remove.

Like any other machine, slurry pumps require regular maintenance to function optimally and reliably. Without proper care, pumps can suffer catastrophic failures, which can result in unscheduled repairs, potential injury, and facility downtime. Maintenance and Operation of Centrifugal Slurry Pumps offers a unique opportunity to gain insight into slurry pump maintenance and operation. Routine servicing of your submersible slurry pumps is essential, and a key factor to avoid unnecessary expense.

Poor pumps maintenance can lose up to 15% of pumps efficiency; costing pump owners reduced output and hurting their bottom lines. However, while pump owners and operators can perform some of this maintenance on their own, some situations require calls to the professionals. Don’t wait until your pump becomes problematic.

“Prior to performing any maintenance, you should develop an inspection plan to conduct tests and ensure that, if possible, the problem in question will not re-occur. The inspection plan is also used as a guide for adhoc / regular inspections so that you can identify any symptoms which may cause damage to the pumps. These mandatory checks include, pump surging which can be caused by air entrainment into the pump, electrical fault, excessive power consumption, low or no flow, low discharge pressure, vibration or noise, and bearing temperature.” Said Graham Van Bosch, Regional Senior Manager, Metso Pumps Solution.

Metso mill discharge pump

Van Bosch further advises that regular maintenance is essential to keep mining equipment, machines and the work environment safe and reliable. Lack of maintenance or inadequate maintenance can lead to dangerous situations, accidents and health problems not to mention the cost thereof.

According to Kunming Kunshui Industrial Pump Co.,Ltd, China’s professional manufacturer of  slurry pumps with more than 10 years’ experience, the pump is durable, with reasonable assembly and installation, it will show the superiority of reliable, long working life and low maintenance. The following should be checked monthly:

(a), Shaft Seal Repair

Packing seal pumps should regularly check the seal water flow and pressure, and always maintain a small amount of clean water flow through the shaft. To make this, you have to adjust the packing gland on a regular basis, if the filler cannot be re-used, should be to replace all. Expeller sealed pumps use oil cup, more economical, but need to regularly lubricate sealed chamber, rubber expeller ring need not lubrication (some pumps exceptions).

Donovan Higginson, KETO Technical Director, Africa advises on the main steps to consider when maintaining slurry pumps is to ensure that there is minimal leakage from the shaft sealing, as  this tends to cause premature bearing failure. The lubrication of the bearing assemblies must be properly administered in accordance with the pump manufactures specifications and standards. Daily inspection of the pump to ensure that there are no inherent problems such as overheating both on the bearings and the pump casings.

KETO are specialists in the design, manufacture and service of pumps, parts and associated products. They cover the most aggressive applications including mining, aggregate and industrial markets.

(b), Impeller Adjust

The pump performance becomes deterioration as the open impeller and the suction side of the plate gap increasing. This impact for closed impeller pump is not obvious, but there are exceptions.Due to wear and tear, the gap increases and pump efficiency is reduced. In order to maintain the high efficiency of the pump, impeller must be timely moved forward, this adjustment just a few minutes and without disassembly any parts.After adjusted, it needs to check the impeller rotation before start the pump, and also check the bearing housing fastening bolts are tightened.

(c), Bearing Lubrication

Bearing components properly assembled and pre-grease lubrication, after shaft-mounted to the bearing housing, if there is no water or other sundries intrusion and timely maintenance, the bearing components are not only reliable but also long life.

Maintenance technician must check the bearing box to observe the bearing and grease regularly(interval not more than 12 months).

The number of regular lubrication and the injection of grease depends on many factors and the interaction of them. They are include speed, bearing specifications, continuous working hours, the pump stop and work time ratio, the working environment – for example, cycle and operation temperature , splash, contamination or the presence of impurities.

Most of the pump bearings run low speed, but there is the risk of damage, mainly due to excessive lubrication of bearings, but preventive measures of avoiding excessive lubrication cannot completely guarantee the maintenance of bearings, the ultimate deciding factors are lubrication experience and judgment to determine the lubrication program, the better approach is to persistent observation the early stages of bearings operation, carefully recorded the unusual circumstances, for example, temperature and purity.For continuous operation, the bearing operating temperature shall not exceed the grease to lose its sealing ability.

(d), Replacement of Wearing Parts

The slurry pump bearing wear wear rate is a function of abrasive characteristics and materials of pump and working conditions. The life of wearing parts such as impeller and liner are different of pumps and pumping stations.

The life of wearing parts such as impeller and liner are different of pumps and pumping stations.

When the pump is first to be used for specific conditions, accident may happened especially during this operation cause of wearing parts losing effectiveness, you should regularly check the pump and bearing wear, to estimate the degree of wear in order to estimate its useful life.

(e), Standby Pump Maintenance

The standby pump should be turned 1/4 rotation a week, in this way, all bearing rotation under static and external vibration.

Bill Naokes of Atlanting pumps advices that, slurry pumps are designed and specified to last as long as possible in the applications in which they work. However, there are some parts that are wear parts by the very nature of the pump and applications to which it is applied, such as the impeller, the volute liners, and components of the sealing system and the bearing assembly. Mr. Naokes recommend that the pump user carries a stock of the main wearing parts to minimize downtime. The frequency with which the pump needs servicing depends largely on the application, but its recommended that the pumps performance (head and flow) is verified monthly against the original or start-up duty point, as this will indicate the condition of the wearing parts.

According to Sara Johnston from KETO, regular adjustment and lubrication of the glands preventing premature failure of the shaft sleeve due to the ingress of slurry into the packings. Regular adjustment of the pumps impeller clearances, to ensure optimum performances of the pump throughout its life cycle.

Slurry pump technology

New technologies are mainly based around the development of higher resistance to wear materials. Depending on the application of the pump, wear is often a higher cost factor than higher efficiency or lower power consumption. When applying a Total Ownership Cost (TOC) to a pump, the cost of downtime and spare parts often out ways the cost of power. KETO have a number of TOC models that can be used to assist in establishing control of these costs. Condition monitoring is being applied more and more to the pumps, as this is helping to more accurately predict Mean Time Between Failures (MTBF), preventing unscheduled downtime. KETO can assist in establishing and providing a tailor-made Condition Monitoring system to meet the various requirement.

According to Bill Naokes, Centrifugal pump technology is decades old, however new materials such as polyurethane are now being used instead of the traditional rubber or high-chrome wearing parts in some applications. Big advances are being made in remote sensor technology, which allows pump users to remotely monitor the condition of their pumps, and intervene before the pump fails when a problem is detected.

At Metso, they continuously seek new ways of thinking and better ways of working. Additional to this, they encourage the introduction of new technologies, and they value innovative ideas and practices. A good example is the Condition Monitoring Technology (CMT). CMT monitors and predicts possible failure causes that the slurry pumps may be exposed to and helps you to proactively eliminate those problems. In this way, your maintenance plan is based on a proactive action plan instead of a reactive plan.

Africa slurry pump challenges

Environment and climatic conditions are often uncontrollable, however, social, health and pollution awareness training programmes are all important considerations. Improving and developing equipment which can operate using less water, i.e. pumping higher density slurries. KETO provides training in a number of these areas, on-site and off-site

“The African market presents both challenges and opportunities for the slurry pump market. Significant mineral deposits are spread over large areas with challenges from a hostile climate, areas of unrest politically, and infrastructure that is in need of improvement. This leads to difficulties in getting pumps and spares to site. Pumps also require a large amount of electricity to run, and this power is required in remote areas and also in remote parts of a mine,” says Bill Naokes

He adds that, with years of development and deployment, slurry pumps can be built to cope with the most demanding of conditions and transport the most abrasive and corrosive liquids. In cases where electricity is unavailable or unreliable diesel pump sets can be used or diesel generators.

According to bill, as confidence returns to the mining industry, investments will be made in expanding the industry and the infrastructure to support it, given that umps are getting more efficient and easier to monitor and control from a remote location. This can only be good for slurry pumping in Africa.

However, Metso offers skills transfer services through various training programs to combat this challenges. Additionally, Metso, offer comprehensive Life Cycle Services (LCS) that can also include pumps maintenance. Their LCS offering includes the entire range of their leading services and equipment ranging from basics to more complete solutions. They offer four types of LCS packages that are adaptable to the customer’s needs:

  • Scheduled inspections: Their service technicians reduce the customer’s risk of major equipment failure, critical parts damage and safety issues through early detection of potential problems and recommended maintenance strategies.
  • Shutdown and wear parts optimization: This serves as the backbone of every successful shutdown. Their first focus is on increasing availability by getting the customer’s equipment back up and running after a shutdown to minimizing lost production time. Secondly, they improve customer efficiency by optimizing process equipment’s wear and spare parts for longevity and highest productivity rate. Basically, they take care of every shutdown step and process.
  • Shutdown and process optimization: This module helps improve the mineral processing workflow. With their equipment expertise complementing the customer’s operational knowledge, they help optimize the operations shutdowns, equipment set up, controls and blasting practices to ensure production gains, safety and efficiency.
  • Maintenance and process optimization focuses on developing complete maintenance strategy based on the customer’s specific site conditions, to increase reliability and maintenance efficiency.

Metso is the only company that offers a single package covering the build, operation and maintenance of customers’ equipment. Considering the increase in copper price and the high demand in metal, cobalt, graphite and the likes, indicates that the future looks positive for slurry pumps in Africa. Many of the EPC brown fields and green fields projects currently worked are entering into an execution stage during 2019.

However, the future outlook for slurry pumping in Africa is improving due to the increased demands for the various minerals currently being mined. Political stability will also play a major role in the future outlook for slurry pumping in Africa. KETO are currently addressing many of these issues with improved component designs, new and improved materials to improve part life and performance.