Insights

Keep On Running - International Mining

This story originally appeared in the September 2013 issue of International Mining and was re-printed by permission.

The right strategies and tools for long term maintenance of equipment are vital to the success of any mining and processing operation, reports Paul Moore, International Mining.


In a recent paper from Alstom MSc (formerly Sigma MSc) entitled Prevent Your Machines Taking Sick Days – Essential Health Monitoring for Your Critical Assets, the company points out that mining is no longer the people intensive industry it used to be. With the introduction of large-scale mechanisation, mining has become a machine-intensive industry and machines are one of the most expensive factors in mining. An industry model for an open pit mine producing 80,000 t of ore and 80,000 tonnes of waste per day estimates the cost of the required machinery to be in excess of A$47 million.

Alstom MSc states: “Rotating machines – such as conveyors, stackers, reclaimers, shovels and shiploaders – are critical assets in mining and, just like mine workers, these machines also need regular health checks in order to remain fit for work as mining operations depend on them working at their full capacity. Mining machines are under constant stress, making problems and malfunctions inevitable and generally unpredictable.  Unanticipated failures of rotating machinery can quickly become extremely costly for mining companies.” In particular,the dependence on conveyor belts means mines can potentially lose up to A$1.4 million per hour in downtime every time the conveyor belt has to be stopped to allow rollers to be replaced.

On average, Alstom estimates that mining machinery maintenance accounts for 30-50% of the operating costs for Australia’s mining industry, amounting to about A$10-15 billion per year. When adding on to that the cost of a new conveyor or shiploader and the mine’s maintenance cost is significantly increased.

IM readers are very familiar with the distinction between regular preventative and intermittent reactive maintenance. The major drawback to reactive maintenance is that the cost of repairing or replacing the machine, as well as the cost of downtime, tends to be much higher than if the problem was detected early and prevented altogether. But what is often not considered is that on the other end of the scale, there is often time-based regular “preventative” maintenance taking place unnecessarily, when there is nothing wrong with the machine, which can actually create new problems. Alston MSc estimates that about 30% of preventive maintenance efforts are wasted, with another 30% actually harmful.

“The most effective maintenance process that mines can adopt is condition-based maintenance; this is based on the actual physical condition of the machine, rather than the clock or calendar” says Alstom. “Ideally condition-based maintenance will allow the maintenance personnel to do only what’s needed as they’re using real-time data to prioritise and optimise maintenance resources.  Adopting a conditioned-based maintenance process minimises the need for spare parts, reduces system downtime and time spent on maintenance and it also provides peace-of-mind knowing everything is functioning as it should be.”

Another recent article by Martin Jackson, Global Custom Care Manager at CDE Global, the supplier of large scale washing solutions, assessed what he described as “the often underestimated benefits of preventative maintenance.” Carrying out regular maintenance inspections on key plant will ultimately reduce downtime, increase operational efficiency and ensure that the risk of expensive reactive work is reduced substantially through planned and routine checks.

In addition, preventative maintenance measures can drastically reduce faults in day-to-day operations, as well as increase the overall readiness of plants in case of unexpected level of processing requirements. CDE Global states: “Not only does regular maintenance improve and extend the life of the plant by preventing excess impairment,maintenance includes and is not limited to adjustments, cleaning, lubrication, repairs and the replacement of parts. Moreover, having the ability to prevent possible issues from arising in the future and causing downtime will also avoid interference with your ability to deliver a quality customer service. It is our experience that the cost of maintenance can be three times higher if no form of preventative maintenance program is in place.” The group also points out that often a mine does not experience problems with equipment at the outset, and therefore the value of maintenance gets dismissed, but only until the mine encounters a problem at first hand.

CDE states: “In order to remain competitive by keeping running costs down and increasing capability, we need to move away from the 'repair focused' attitude and adopt a 'reliability focused' outlook. Furthermore, by maintaining plant equipment effectively, not only are you maximising production, you are also minimising the depreciation of the plant in terms of wear and tear throughout its lifetime...you will avoid reducing the average rate of throughput, you will avoid increasing operating costs and more importantly, you will avoid impeding customer service.”  Due to the varying needs of different plants, the type and amount of preventative maintenance required varies greatly but ultimately, it will ensure that the maximum level of mined material is processed into high quality end products.

Vibration monitoring
One key technology that facilitates condition based maintenance is vibration monitoring. The fact it can be applied to a wide range of rotating equipment makes it one of the most widely used condition-based maintenance technologies.  Machine vibrations come from many sources – such as bearings, gears and unbalance – and can cause malfunctions, damage and unmanageable stress on the machines if of a high level. Even a fractional change in readings could indicate a problem with the machine.  Vibration monitors allow the mine to identify the problem and fix it before it develops into something much bigger.

Alstom MSc specialises in vibration monitoring and offers a range of relevant products including portable, online and wireless solutions. The company says it recently worked with an Australian mining operation that had not adopted a vibration monitoring process on a critical conveyor system; a malfunction caused the conveyor to be unusable for two and a half days, costing the facility in excess of A$10 million. The plant is now equipped with innovative wireless vibration monitoring solutions to prevent this catastrophic loss happening again.

Hansford Sensors states: “Rotating machinery such as motors, gearboxes, pump, screens, crushers and conveyors must be continuously monitored to warn of bearing and component wear but is frequently installed in areas that are difficult to access. The use of remote vibration monitoring systems enables both performance and safety levels to be maximised, as engineers are no longer required to come into close contact with potentially hazardous equipment. This is one of many reasons why the technique of vibration monitoring has been accepted and proven as a highly cost-effective method of maximising efficiency and profitability in the mining industry.”

Hansford Sensors has supplied thousands of industrial accelerometers worldwide to mines, including ATEX certified solutions for potentially explosive gas atmospheres, for example, in underground coal mines. For example, within the mining sector it is common to monitor conveyors that are running under 60Hz. In these situations a higher sensitivity sensor, for example, 500mV/g (HS-100 Series) can improve the signal to noise ratio and increase the capability of conducting a full data analysis.

Whether the sensors are to be installed on a crusher, screen, conveyor pulley or drive, Hansford Sensors recommends a side-entry/low profile model. If conditions permit, top-entry can be used, but the location of the sensors may need to be reviewed to ensure debris (for example, coal falling from a conveyor) cannot damage the sensor. Some mining environments are suitable for installing top-entry sensors, for example in a pump room.

In these areas, Hansford Sensors says it would advise using top-entry unit for a more cost effective solution. The company states on practicality: “Hansford Sensors has addressed the needs of its customers in the mining industry by listening to them and responding with some common sense solutions. For example, one customer commented that when dust settles on the lid of a standard enclosure it can fall inside when the lid is opened, so we now provide an enclosure that has a sloping roof. We also now supply a compact box for customers who find that a standard box is just too big for their application. The products that were created to respond to these needs were the HS-SC Series Compact Enclosure, which is designed for applications where space is limited, and the HS-SR Enclosure with Sloping Roof, which protects against dusty and dirty environments by allowing run-off of contamination.”

Software solutions
Dingo Software, the provider of heavy asset management software and services, has formed what it believes is the world's first Global Asset Wellness™ network. “Customers will now be able to receive expert maintenance insights on a wide range of mining assets anywhere, anytime” said Paul Higgins, CEO of Dingo. After developing this Cloud-based approach with customers in 2007, Dingo’s Asset Wellness™ network now protects over 70,000 major components daily, having received and processed tens of millions of data samples “from a large range of sources” including oil analysis labs, vibrations systems,VIMS, Komatsu VHMS, Detroit DDEC, Cummins Cense, Equipment Management Systems, SAP, tyre wear, component inspection reports and images, CMMS work orders, undercarriage wear, and fluid consumption.  Data entering the network is converted into proactive work using Dingo’s Trakka® software, which first filters the information using sophisticated rules and statistics, passing identified problems to teams of experienced maintenance experts for real, contextual decisions. This announcement links Dingo’s global Insight and Action Centres and extends coverage across all time zones, “meaning lower risk and higher responsiveness for customers”, says the company.  Dingo’s network is comprised of dedicated Asset Insight centres in Brisbane and Denver, connected to Asset Action centres in the UK; Muswellbrook, New South Wales; Timmins,Ontario; Fernie and Kamloops in British Columbia; Madisonville, Kentucky; Silver City, New Mexico; Boise, Idaho; and Elko, Nevada.

This Asset Wellness™ network is connected to customers through the Cloud-based Trakka® software and to data sources through Dingo’s Connector Library. “Much like in human health, asset intensive industries are looking for ways to push the boundaries of what it means to operate in an optimum state”, said Higgins. ”In a recent example, a Dingo customer, whose five mines are served by Dingo’s Denver Insight centre, realised a 19% improvement in average life across an entire mining system. This was achieved through close monitoring of health indicators, combined with rapid action on recommendations issued directly from Dingo’s Network, to maintenance staff.  Users benefit from analysis of the largest OEM-independent database of comparative machine performance information,” commented Colin Donnelly, Dingo’s Director of Engineering. “Our goal is to make it easy for asset managers to find and fix problems before they become an expensive failure, and to take care of their machines so they can maximise their longevity.”

In mining, Dingo says its systems “drive real results of increased availability and reduced operating costs”, which it says provide a typical payback of more than threefold within a year.

Lifting and handling
With personal safety paramount to every mine’s daily operation, any potential injury hazard needs to be identified and removed. Durapac’s SAFE D LOCK hydraulic jack helps to remove the risk to operators in the lifting of heavy mining vehicles for tyre replacement or maintenance by providing an easy-to-use air driven hydraulic jack that can be mechanically locked by the press of a button.  Designed and built to meet the Australian and New Zealand Standard 2693:2007 as a vehicle jack, it also meets the Australian and New Zealand Standard 2538:2004 for use as a rated vehicle support stand. This means if the jack is to be used as a rated vehicle support stand, it must support three times the jack’s rated capacity without failure.

Currently there are two models of the Durapac SAFE D LOCK jack available: the SDL-15068, a 150 t jack with a collapsed height of 680mm with a rated vehicle stand lift height of 1,408 mm; and the SDL15096, 150 t jack with a collapsed height of 960mm with a rated vehicle stand lift height of 1,650mm. Further 200 t models are also set to be released.

Durapac states that there are a number of key features around the SAFE D LOCK jack that set it apart from others on the market. The hydraulic system is powered by an air-driven GastR 3.9 kW motor and the jack uses patented oil-bathed internal spring loaded locking quadrants that are constantly energised during the lifting process to give a fail safe operation. This locking mechanism automatically engages in the event of a hydraulic failure. A 5m long anaconda hose with attached remote pendant allows the jack operator to work at a safe distance from the vehicle being lifted.

A remote pendant has two display indicators that confirm to the operator the jacks’ status (either locked or unlocked). To mechanically lock the jack the operator only needs to press the lock button on the remote pendant; thus avoiding an operator having to enter the lifting area to physically secure locking rings on the jack or to ensure that the vehicle is mechanically supported. Finally, given the extreme and varied working environment in which these types of jacks are used, all moving components of the SAFE D LOCK are enclosed or shrouded to avoid dirt,rocks and mud entering into the jack's working mechanism.

Hedweld has two main product ranges: the Trilift component handling equipment and the Safe-Away ladder and stairway access system.  Mark Gream, Global Products Manager, Hedweld USA, explained that the company can fit a ladder or stairway to every piece of equipment on a mine site from a small system for a grader or a scraper through to a large system for a dragline or a shovel. The Safe-Away products increase safety for maintenance and operation personnel, reduce down time and use innovative designs and the latest technology.

On the large equipment side, Hedweld’s Trilift 797 transmission hoist came about from requests from around the world to come up with a safe and more efficient method of removing the transmission from Cat 797 trucks. Most mining trucks are built without the dump body on so the transmission is dropped in with an overhead crane - which is quite easy to do without the dump body in place. But if you have to remove the dump body to remove the transmission in a workshop it is an expensive, time-consuming task and there are a lot of safety issues associated with removing a dump body. Hedweld came up with the Trilift 797 Transmission Hoist to eliminate the need to take the dump body off.

The traditional method is labour intensive and requires a lot of space.  Gream believes that the Hedweld 797 Transmission Hoist is safer, less costly and more convenient than a knuckle boom or a cherry picker type crane. The company states: “Syncrude in Canada has a large fleet of 797s that faces severe climate challenges and is a remote location so the hiring of cranes onto the site is almost impossible. The first time Syncrude used the Hedweld 797 Transmission Hoist the transmission was removed and replaced in under an hour.  Syncrude also reports that it has improved the safety of the process, it can be used in the confines of one bay, it has reduced downtime and improved the efficiency or transmission change outs.”

The Hedweld system is a main frame carrier which is designed to be lifted onto the chassis rails of the truck with the dump body raised in the air (the dump body stays on the truck so there is a cost and time saving there). It uses a hydraulic powered winch to lift the transmission out of the hole and then the whole machine is lifted off the chassis rail with the transmission inside it. It adds a walkway and handrails to the top of the chassis rail making it safer for personnel walking around on top of the transmission. It also adds fall restraints and provides better access to the transmission for the purpose of the removal. It has a safe working load of 8,000 kg, so while the transmission weighs about 6,500 kg, there is plenty of spare capacity.

Power system maintenance
Marty Trivette, Product Marketing Leader – North America at GE’s Industrial Solutions business, draws attention to the fact that despite advances in electrical distribution, power distribution still poses a very real safety danger at mine sites. An arc flash—an immensely powerful burst of heat energy created by the release of energy from an electric arc—is one of the most serious and common causes of non-fatal electrical injuries in the mining industry. Many arc-flash incidents occur during the servicing of electrical equipment. For example, an action as minor as dropping a wrench can cause an arc-flash event if it falls across conductors.

One way mining companies can limit the possibility of an arc flash and minimise the effects of an incident is to work with electrical distribution experts to preemptively assess their risk for an arc-flash event. For example, GE trains and certifies its power system engineers to perform comprehensive arc-flash hazard studies in accordance with NFPA Standard 70E.  Armed with this information, power system engineers can assess arc-flash danger on-site and minimise its potential risk. Mining companies can minimise arc-flash danger by adopting end-to-end safety improvements with initiatives such as creating and deploying a complete arc-flash strategy; conducting ongoing employee training; matching arc-flash protection equipment and clothing with the level of risk; and identifying and evaluating arc-flash potential throughout a location. The mine can also calculate incident energy exposure and arc- flash boundaries and place warning labels to indicate arc-flash hazard levels.

GE states: “While education and precautions can reduce arc-flash occurrences, they can never be totally eliminated. Setting up arc-flash mitigation strategies can greatly reduce the energy expelled during an arc-flash incident and minimize worker injuries and equipment damage.” For example, instantaneous zone selective interlocking (I-ZSI) – previously regarded as unobtainable – delivers simultaneous selectivity and arc-flash protection 24/7 to mining companies, improving worker safety and equipment protection, while reducing system downtime. In addition, the implementation of reduced energy let-through (RELT) technology and retrofitting fuse technology load interrupter switches with faster circuit breakers,mining companies can dramatically limit arc-flash time and significantly reduce its energy.

Failures of electrical equipment in mines can cause production losses worth millions per day.  But most are predictable and avoidable, according to Australia’s EA Technology. The company’s Brisbane-based Managing Director Keith Beven said: “The cost of lost production from unexpected failures of electrical plant such as switchgear, transformers and cables is typically many times the cost of preventative testing and early intervention.  Our focus is on keeping power assets working reliably to maintain production. The bonus is that managing electrical assets based on measured condition rather than with scheduled maintenance actually costs less and increases uptime.”

The company has developed a market-leading range of instruments for measuring Partial Discharge (PD) activity in live plants – small electrical discharges which give an accurate indication that equipment is starting to break down. The ability to detect, locate, measure, monitor, record and analyse PD activity enables EA Technology to predict when plant is likely to fail, and estimate its time to end-of-life.

EA Technology’s product range is led by its UltraTEV instruments, which it states are the world’s leading multi-sensor PD measurement instruments, using a combination of ultrasonic sensors to measure surface PD and Transient Earth Voltage (TEV) sensors to measure internal activity.

The company has also developed a complete Condition-Based Risk Management(CBRM) system, which enables asset managers to prioritise the replacement of plant, based on the probability and financial consequences of it failing.

Tyre management
Adrian Leu, Yokohama Senior Technical engineer, OTR, has provided IM with some advice on tyre management, starting with the main tyre safety issues operators should be aware of. “Choosing the proper tyre for the specific vehicle and application, using correct tyre inflation pressure settings, following proper inflation adjustment practice and careful tyre inspection are the primary issues.” To avoid dangerous situations related to these primary safety concerns, the following action points are important:

  • Consult with the equipment manufacturer, tyre manufacturer and/or tyre dealer to ensure that you have chosen the correct tyre for your application
  • Correct inflation pressure is defined by the load carried by the tyre. In most cases this information can be found in a tyre manufacturer’s data book, along with other useful and relevant information in regards to safe tyre practices
  • Prior to the beginning of a shift, a cold inflation pressure check should be completed. Tyres that have internal temperatures that are the same as ambient temperatures are considered cold
  • Educate people on how to inspect tyres for damage or other possible safety issues.  Maintaining proper inflation pressure is the key to optimising tyre performance and yielding the safest operating conditions for the tyre
  • Always stand clear of a tyre/rim assembly that is being deflated or inflated. Assemblies not installed on a vehicle should be placed in a safety cage or restrained before any inflation service
  • Use a clip-on chuck. Use inflation hose long enough to stand to side of tyre. Do not stand in front or back of tyre assembly
  • Never introduce a flammable substance into a tyre before, during, or after mounting
  • Never 'bleed’ the air from a ‘hot’ tyre. Adjust the air pressure only when ‘cold’ (inside tyre temperature is the same as the outside temperature)
  • Never use a tube in a tubeless tyre where the rim assembly is suspected of leaking
Tyre inspections should be completed each shift or when a tyre impact or injury event has occurred. “If you feel that a tyre could have a possible condition rendering it unsafe for normal operation,report that to your supervisor immediately for immediate action and further inspection.”  The following are conditions that are present that would render a tyre being unsafe to use:
  • Any punctures or other penetrations
  • Any inner liner or bead damage
  • Indication of internal separation, such as bulges or local areas of irregular/fast tread wear indicating possible tread or belt separation
  • Indication of run-flat, under inflated and/or overloaded damage (such as inner liner abrasion, mid- to upper sidewall abrasion and stamping deterioration, delamination, or discoloration, excessive tread shoulder wear)
  • Any damage or wear exposing the body material of the tyre—cuts, cracks, bulges, scrapes, ozone cracking/weather checking, impact damage, punctures, splits, snags, etc.
  • Currently mounted on a rim that is bent, dented, cracked or otherwise damaged
  • Chemical, fire, excessive heat damage, or other environmental damage
  • Designated as a ‘scrap tyre’or otherwise not intended for continued service
  • Any other condition which would be cause for permanent removal from service.
Asked about some of the most common errors operators make when handling tyres, Leu responded that they “need to be aware of the tyre performance limitations. Exceeding a tyre’s speed, load or distance capabilities can subject a tyre to unwanted abuse which may shorten its life.  "Other mistakes include being overly aggressive on the throttle can cause tyres to spin, which can cause excessive tyre wear, introduce spin cuts as well as generate heat buildup which may also shorten the tyre life.  Underinflation or overloading creates excessive stress and heat, and can lead to tyre failure. Maintaining and using proper inflation pressures is important regardless of how it affects vehicle’s handling performance.  Over-inflation can make the tyre more susceptible to impact damage.

Maintaining proper inflation pressure is key to optimising performance. “This is turn will yield the safest operating conditions and reduce the likelihood of an early tyre failure. Also, it’s always best to leave some tread remaining for safety, the ability to retread or just to be sold as a casing.”

Seth Schneider,Vice President of Development at Pneumacore, believes that there is a lack of focus on a potentially deadly problem with mining vehicles - wheel and rim cracks. "A critically important component of any tyre maintenance program is to help identify rim cracks," says Schneider. "Many companies incorporate Simoniz Life X-Tend (a tyre and rim conditioner) into their maintenance programs.  Life X-Tend seeps into microscopic cracks in the rim, helping identify potentially catastrophic problems. I left the expo thinking on how to improve on this product."

SENTRY is the result, Pneumacore's patent pending enhanced version of Simoniz's Sealtite Life X-tend tyre conditioner. It has fluorescing properties to enhance the detection of rim cracks, bead leaks, punctures, or any other signs of air loss and “is the only product of its kind,” the company says.

Developed specifically with low visibility environments in mind, such as underground mining and nighttime driving conditions, Pneumacore “has developed the world's first fluorescing rim conditioner.  Of course SENTRY works equally as well in daytime or above ground environments.”

In the US, OSHA requires all cracked rims to be removed and serviced or discarded. Easily identified with the use of a specially developed UV light, catastrophic failures due to rim cracks can become a thing of the past.

“Simoniz SENTRY is used to identify rim cracks, bead and vent hole leaks, and punctures. SENTRY keeps the bead area pliable and the inner liner supple, prevents rim corrosion with the strongest anti-corrosion package in the industry, is more stable at higher and lower temperatures than other leading tyre conditioners, and has greater lubricity than other conditioners, allowing for easier mounting and dismounting of tyres.”

In-pit servicing
Scania unveiled the latest addition to its growing range of mine-spec vehicles at AIMEX last month. According to Scania, the new P360 4x4 has been developed as a general-purpose stores truck for on-site use. “The first of these vehicles we delivered has been specified with a locally sourced flat top tray with twistlocks, as well as toolboxes, watertank, and mine-spec lights,” said Robert Taylor, General Manager, Scania Mining Services. “Like every Scania, the P360 4x4 has an all-steel cab that has been impact-tested to exceed the Swedish and European standards.”

The company has equipped the 4x4 with its Scania Opticruise clutchless manual gearbox, which allows drivers to take manual control of gear changing if required. “One of the benefits for mine customers is that all Scania trucks have an identical layout, so if you hop into the 4x4 after driving an 8x8 service vehicle or ANFO truck,the controls are all in the same place,” said Taylor.

While the new 4x4 is powered by a 265 kW six-cylinder engine, a variety of power outputs in a number of configurations are available. The truck has a 13t payload capacity and offers a 10-year working life.

Scania’s heavy-duty truck range also offers the G360 dump truck, which is delivered from Europe with the dump body attached ready for work. There is also an 8x4 G400 flattop complete with HIAB lifting arm, designed for lifting and transporting machinery and heavy items from site to site; it can be hitched to a dog trailer for extra capacity. Another new addition to Scania’s mining range is an 8x4 G400 tilt tray, incorporating a large capacity load bed and hydraulic arm.

One of the company’s heavy-haul R620V8-powered prime movers, able to pull up to five trailers with a payload of up to 170 t of ore, was recently tested at a Kalgoorlie gold mine, where it was rated at 200 t GCM, pulling four trailers and 140 t of ore.

Another mining success for the company is its Scania-Higer A30 mining bus, which seats up to 60 work crew. Fitted out with full mine-spec safety equipment, a mine site operator in north Western Australia has more than 30 of these already in service.

According to Taylor, the Scania Total Transport Solution “concept goes far beyond the supply of vehicle hardware and includes tailored specification per customer of a range of mine friendly vehicles, as well as pre-delivery driver efficiency instruction, to ensure the vehicle is not only used safety, but also in the most efficient manner.”

As part of this, Scania offers a tailored maintenance and repair program that delivers full vehicle cover for a pre-determined period with a known monthly cost. “For hard-working older vehicles, a preventative maintenance campaign ensures that uptime is not impacted by unexpected failures,” said Taylor.

In addition,the company’s fly-in fly-out, remote area servicing program gets its factory trained experts into the field to carry out maintenance and repairs on equipment, reducing downtime and ensuring repairs are carried out correctly. The Scania Total Transport solution also ensures suitable quantities of service parts are always available where customers elect to carry out their own maintenance.  

Fuel and lubes
Pall Corp’s Dr. Christian Bauer explains that modern mines are among the world's largest consumers of diesel fuel, with an annual consumption of more than 200 million litres of diesel fuel. The fuel that is delivered to these mines can contain as much as 20mg/l solid contaminants, but, he says, “vehicle on-board fuel filters are not designed to tolerate high contamination levels without significant impact on service life; most engine manufacturers have issued specific fuel cleanliness requirements, particularly for engines with common rail fuel injection systems. Therefore, contamination control throughout the entire fuel supply chain is critical.”

He notes that without bulk or point-of-use filtration,the service life of on-board filter elements can vary greatly as a function of the contamination concentration in the incoming fuel.  He stresses that the “service life of onboard filter elements must coincide with vehicle maintenance/service intervals.

“High-performance, point-of-use and/or bulk filtration is recommended to ensure a consistently high fuel cleanliness going into the vehicle's fuel tank.”

CC Jensen says that what makes it unique is its “combination of tradition, innovation and technical expertise.”  Its CJC oil filtration filters and CJC filter inserts are available globally, and the company considers that routine oil changes in mobile equipment rear differentials cost time and money and do little to improve equipment reliability. The high viscosity oil drains slowly and leaves a trail of contaminants to lessen the efficiency of the new oil. It says that “cleaning the oil to OEM recommended levels with a depth filter media reduces contaminants like wear particles, water and varnish and extends the oil life while improving equipment reliability.” In one example, oil life increased from 18,000 to 25,000 hours and wheel rebuilds decreased from 16 to 12 per vehicle per year, thus saving $500,000 annually.

Shell argues that the right lubricant and fuel choices can play an important role in reducing maintenance costs and downtime. “Mining customers recognise the role lubricants play in reducing their maintenance costs, equipment downtime as well as extending equipment life. Compared to the cost of the lubricant, the potential impact of inadequate lubrication on maintenance costs and productivity is massive, which makes our customers’ expectation of us equally great. The cost of a replacement gear on a dragline, or the production lost while a shovel is down for maintenance can quickly go from a few thousand dollars to tens of thousands. To take full advantage of what a lubricant can do, the right product must be used. Such a decision can seem straight-forward but can get complicated by the number of lubricants available and the complexity of the specifications they are required to meet.” Depending on the application, some lubricant characteristics are more important than others. For example, a specific grease could have excellent wear protection performance but get easily washed away by rain or be squeezed out by the high loads that these machines experience."

The second step is to ensure the lubricant is properly applied.  Many costly breakdowns occur due to the lubricant not reaching the surface it is intended to protect. Again a partnership between the lubricant supplier and the customer leads to the best results. Shell states: “We help our customers by offering regular lubrication surveys and routine critical equipment inspections. These allow us to recommend corrective actions and train their staff on best lubrication practices.”

Another consideration is the constant evolution of new mining equipment, which presents new lubrication challenges: “Our customers look to us to bring new products to market that are capable of protecting this new equipment, as well as providing appropriate protection for existing machinery. Many customers are open to trial new products with us because they trust our capability to develop these products and to manage field trials regardless of the outcome.Our customers are looking to extract the value of innovation across their entire operation – the more complex the operation the more significant the challenge becomes. Our capability to leverage our global reach to be part of that value extraction process is seen as a key strength by our customers.”

Fuel choices can also have a impact on the maintenance of the heavy duty engines in mining applications.  Over time and with intense operations, deposits may build up leading to fall-off in performance and the need for increased maintenance. Replacing rusted engine parts can also cause costly downtime. Shell states that its experience in markets like South Africa shows that the use of advanced fuels can make a significant difference. Products like Shell FuelSaveDiesel, Shell Diesel Extra and Shell Diesel with Economy Formula contain specially formulated detergents designed to keep engines clean from carbon deposits, and a special corrosion inhibitor helps prevent fuel system corrosion. This in turn can help reduce maintenance frequency and costs, and improve the reliability of equipment. These fuels are also designed to promote more efficient engine performance; by enabling up to 3% fuel savings over the life time of the equipment or vehicle.  Other advantages include lower fuel-related exhaust CO2 and black smoke and easier maintenance of storage tanks through reduced water contamination.

Coal mining group Alpha Natural Resources reported on its Diesel Engine Conversion Project in its 2012 Annual Report. The project is identifying opportunities to minimise the environmental impact associated with the mining process. “This year, in partnership with GFS Corp, we identified opportunities for efficiency through fuel conversion solutions for the high-horsepower diesel engines found in many of our trucks and other mobile equipment.  By retrofitting these large diesel engines to operate on a mixture of diesel fuel and natural gas or methane-based fuels, we have reduced emissions and increased savings. So far, we have displaced 22% of our diesel fuel needs in our haul truck fleet.”

Heavy-duty diesel engine oils, hydraulic oils and greases work hand-in-hand to enable mobile machinery on mining sites to operate effectively. While the primary function of a lubricant is to protect equipment, reduce unscheduled downtime and extend oil drain intervals, advancements in lubricant technology now mean mining companies can select oils and greases which provide outstanding levels of protection as well as other potential benefits such as improved fuel economy.

Mobil’s DTE 10 Excel hydraulic oil is one example of lubricants which have raised the bar in terms of delivering productivity and sustainability related benefits. It has demonstrated exceptional oil life, outlasting standard hydraulic oils by up to three times, whilst maintaining outstanding hydraulic system cleanliness and component protection. As well as offering excellent ‘start-up’ protection, Mobil DTE 10 Excel can also successfully operate in temperatures as low as -34°C. Mobil states: “In addition to excellent protection, even in extreme conditions, Mobil DTE 10 Excel hydraulic fluid has demonstrated the ability to help provide quantifiable increases in hydraulic efficiency compared to standard hydraulic oils. In controlled laboratory efficiency testing, Mobil DTE 10 Excel was measured to provide up to a 6% improvement in hydraulic pump efficiency compared to our standard hydraulic oil, when operating in typical hydraulic applications.”

According to a taconite mining operator in Minnesota, Mobil DTE 10 Excel has delivered more than $43,000 in annual savings by helping to improve the hydraulic system reliability of a large wheel loader.

During Minnesota’s winter months, ambient temperatures can reach -40°C and lower in taconite mining pits. The cooling function of the mining operator’s large wheel loader does not function adequately at these extreme temperatures, causing the hydraulic system to shut down.  Following the introduction of Mobil DTE 10 Excel,the operator has reported a reduction in cold weather hydraulic system shutdowns by 75%, extended oil drain intervals from 2,000 h to 8,000 h, and doubled the life of the pumps.

The heavy-duty diesel engine oil, Mobil Delvac 1 ESP 5W-40 is another product engineered to deliver productivity and fuel economy benefits to mining customers. At the La Herradura mine in Mexico, Construplan operates more than 40 pieces of heavy-duty equipment, including large trucks, heavy-duty pickups and excavators that rely on Mobil Delvac 1 synthetic heavy-duty diesel engine oil.  Along with heavy loads,the equipment at the mine is often subjected to extreme conditions - ranging from 50°C in the summer to -10⁰ C in the winter. Since implementing Mobil Delvac 1 in its operations, Construplan has reported significant benefits, including enhanced equipment performance, increased uptime, improved fuel economy and extended oil drain intervals. As a result, Construplan leaders say they have been able to reduce oil consumption, minimise used oil waste, and maximise the overall productivity of their equipment and people.

High-performance greases also play a key role in maximising the performance of mobile equipment. An operator in Egypt previously used a lithium complex grease to lubricate all pins and sleeves in its earth moving equipment.  However, using this grease was leading to high grease consumption, alongside frequent equipment downtime which was resulting in high labour costs to maintain the machines.  Following recommendations from ExxonMobil, Mobilgrease XHPTM 322 MINE replaced a lithium complex grease in all 27 of its earth moving machines, due to the grease’s proven track record to operate effectively in high vibration, high temperature conditions. The introduction saw an impressive extension in the re-greasing intervals of machinery, extending these on average from 18 h to 50 h. The customer reports this reduction in grease consumption resulted in a saving of $35,700 per year. Furthermore, due to the reduced equipment downtime,the company reports it was able to increase productivity by 1.7% and save a further $46,900/y in labour costs.

Mobil also adds that as part of routine maintenance, the "health" of the lubricant and application itself should be regularly checked.  Typically, it is advised that maintenance professionals perform quarterly oil analyses and annual system inspections. The oil analysis should include a measurement of fluid viscosity, water content, particle count and dissolved metals to determine how well the system is operating. Examining changes in the oil analysis data overtime, also known as ‘trending,’ is necessary to assess the condition of a lubricant.  By trending oil analysis data it is possible to proactively address undesirable conditions before they become problems.

For equipment maintenance professionals who want an effective oil analysis program, there is also ExxonMobil’s proprietary online Signum oil analysis program. Signum oil analysis offers engineers immediate access and direct control of their lubricant sampling program. With a few keystrokes, users can manage their oil analysis needs enabling them to update equipment registrations and select analysis options based on their equipment or maintenance needs; track the status of samples at the lab; direct actions based on analysis results; and share critical results with colleagues in a secure, password protected environment.

Engine filtration
The effects that airborne particulates can have on vehicles, reliability and performance cannot be underestimated. If you are operating in a dusty atmosphere such as mining and have not mitigated for the weather and dust levels, it could threaten your vehicle uptime, increase your cost of maintenance and ultimately degrade profits. Gary Bullock, Business Development Manager at Parker Racor recently looked at how customers can reap benefits with the installation of engine air pre cleaners.

“As a vehicle operator you can safely assume that the original equipment (OE) air filter installed is good enough to do the job it is intended for. Well this assumption is reasonable, if your day to day working environment features airborne particulates of any kind you could be noticing that the OE installed air filter needs replacing often, and sometimes outside of the manufacturers' specified limits.”

A particulate air filter made up of fibrous materials is installed by engine manufacturers with the intent of removing solid particles from the incoming air in to the engine. The air filter captures all kinds of airborne pollutants, which if they get past the filter, can cause abrasion or corrosion. The air filter itself catches all the pollutants within the fibrous material contained within. If the filter gets clogged it will ultimately starve the engine of air, which is vital to the combustion process. In order for the combustion process to be most effective it needs precise ratios of air to fuel. So to ensure that your engine is working at peak efficiency, regular inspection is needed on top of the usual OEM inspection kits.

However there are retrofit options, known as pre cleaners, which can extend the life of standard fit OE filters by a factor of three. Pre cleaners are devices that employ inertial or centrifugal forces to remove a portion (80% of the larger dust particles) of dust and particulates prior to reaching the OE air filter – and they have evolved enormously in recent years. The early days of the technology saw the use of static units, such as dust collection bowls.  Here, air was drawn up through the bottom, over angled vanes, causing the air to spin. The dirt followed the inner wall up and over the edge into the collection bowl while the clean air entered the intake pipe. The major drawback, however, was that this type of pre cleaner required the operator to empty the unit on a daily basis. Following this, pre cleaners using forced dust evacuation were popular for a while, although the need to vertically mount the units to achieve efficient discharge meant they lacked versatility.  For metal construction with black powder coatings, modern engine air pre cleaners provide advanced filtration technology for the pre removal of airborne particulates before they reach the OE installed air filter. Specified usually as a retrofit on to a vehicle the pre cleaners when combined with the standard air filter provide a two-step protection system for today’s precision-engineered engines. Natural air enters the pre cleaner via the air intake on the vehicle. Once into the pre cleaner the device removes a high percentage of particulates that are found in the air stream (in Parker Racor filtration pre cleaners this is stated at 80%). What’s more, the pre cleaners offer low restriction so there is no noticeable difference in airflow.

Either mounted above or under the bonnet but before the OE filter, the pre cleaner sifts and ejects the particulates from the air stream, thus ensuring that the air passed down to the OE filter is considerably cleaner. For best results, the pre cleaner should be positioned as close to the OE filter as space permits, although if mounted close to the exhaust manifold then a heat deflection guard should be deployed.

The latest pre cleaners’ function using an internal rust-proof rotor mounted on dual ball bearings that is made to spin by the airflow entering the engine. Air infiltrates the system through a prescreen that removes large debris.  It then flows through static vanes causing the air to spin. Here, centrifugal force separates dust, dirt, insects, rain and snow from the air stream. The rotor acts as a blower, evacuating contaminants through special discharge ports on the side of the unit.  Only purified air flows to the air filter elements.

For the OE filter itself, the installation of a pre cleaner has a considerable benefit in terms of operational life. What’s more vehicle operators who have installed this technology are seeing OE filter life extended by up to a factor of four.

Parker Racor states: “Due to cleaner air being passed through the pre cleaner,the OE filter naturally lasts longer.  Ultimately for the vehicle operator this means reduced maintenance costs, minimised maintenance schedules, greater vehicle reliability, and reduced energy / fuel costs due to the correct level of air flowing into the engine thus ensuring correct combustion.  Importantly engine air pre cleaners require no maintenance or cleaning. This helps vehicle operators run their machines at peak performance, thus ensuring that operating costs are kept low and profits are retained.”