Gold Mine Saves Millions in Downtime, Repair and Replacements Cost with On-site Oil Analysis

A low-grade surface mining operation relies on large, expensive equipment such as Caterpillar 793 haul trucks and Hitachi 5500 shovels. Oil analysis is required to detect problems so they can be corrected before they cause equipment to go down for major repairs.

In the past, a multinational mining company sent samples for analysis to an outside laboratory, but the cost of this approach restricted the number of samples that could be analyzed. Additionally, the four-day lead time to receive the results created the risk of damage that could occur before the results are acquired.

To overcome this problem, the mine created an in-house lab based on the Spectro FTIR oil analyzer and the Spectroil Q100 rotating disk electrode (RDE) atomic emission spectrometer. Now, the mine can obtain oil analysis results in only 12 minutes, and the reduced cost per sample has made it possible to increase the number of samples analyzed by almost a factor of ten.

In its first year of operation, the lab has identified savings of more than $1 million in downtime and more than $1 million in repairs with several of the larger incidents generating savings that fully paid for the purchase price of the instruments.

Key Role Played by Heavy Equipment

The mines heavily rely upon huge equipment designed to efficiently and quickly move massive amounts of ore. One common example is the Hitachi 5500 excavating shovel which is powered by a 2600 horsepower engine and has a maximum payload of 280 tons. A Caterpillar 793 haul truck can haul 250 tons of ore and weighs 270,000 pounds. A 16 cylinder, 2478 horsepower engine is used to power this truck.

When operating, these enormous pieces of equipment are worth almost $15,000 per hour, so reducing downtime is critical to profitability. Repair costs are also enormous with, for instance, the cost of rebuilding an engine running about $400,000. More importantly, the sudden failure of a major equipment like a shovel or truck can lead to a safety issue.

Value of oil analysis

For a long time, oil analysis has been a significant part of maximizing uptime and minimizing repair and replacement costs at the mine as well as the vast majority of other major mines in the world. With oil analysis, the amount of various metals in the oil can be determined, offering a quick and cost-effective way of gauging the amount of wear in the machinery.

Oil analysis also measures solids formed by oxidation as well as the viscosity of the oil that help determine the oil condition. By monitoring oil condition, the risk of catastrophic failure and the high cost of changing and disposing of oil in heavy machinery can be reduced. An oil sample can be analyzed in a few minutes, and the cost of analysis is very low, making oil analysis a practical and simple way to keep a mine operating profitably.

In the past, the mine used very basic tools to perform some of the analysis itself. However, the lack of reliability meant that the company primarily relied on an outside lab. Although the outside lab provided reliable results, it took two days to deliver samples to the lab and another two days for sample analysis.

Consequently, it was not uncommon for the equipment to have already failed by the time the mine received information indicating a problem. This situation led to downtime and repair costs significantly higher than what would have been incurred if the repairs had been made a few days earlier.

The outside lab charged almost $12 per sample plus $15 for shipping costs, which was another disadvantage of the old method. Due to these costs, the mine’s analysis was limited to an average of five samples per day.

Establishing an In-House Lab

I got management approval to establish an in-house lab and spent over a year looking at different technologies and brands. I concluded that Spectro stands far above the rest both in performance and cost of their instruments. For example, with other instruments the sample has to be pumped through the machine and flushed out, creating the potential for crosscontamination. The Q100, on the other hand, has a disposable wheel that avoids this potential problem.

Reliability Centered Maintenance (RCM) Coordinator

To analyze additives, wear, and contaminants in mineral or synthetic petroleum-based products, the mine uses the Spectroil Q100 atomic emission spectrometer. To measure oil degradation and contamination, it uses the Spectro FTIR oil analyzer. The mine is also planning to buy SpectroT2FM Q500 analytical ferrography laboratory and a SpectroVISC Q300, semi-automatic kinematic viscometer.

It also uses a SpectroTrack laboratory information management system (LIMS), which automatically captures analysis results from the instruments and stores them in a database that can be accessed over the Internet and used to track trends. When a lab technician emails the RCM coordinator to alert him of a possible problem, he immediately logs into SpectroTrack to check the history of the machine and similar machines, which can help determine the best course of action.

Savings in Downtime and Repair Costs

Four problems have already been identified by the in-house lab, and each one of them would have cost more to fix than the entire cost of outfitting the in-house lab - if the mine had relied on an outside lab to identify them. In one such situation, the in-house lab found a glycol leak in a Caterpillar 793 haul truck.

If we had waited for results from an outside lab, we would have ruined the engine which would have cost $400,000 to rebuild. Instead we fixed the leak at a cost of a few hundred dollars. On the same truck a few months later we saw the tin and lead levels in the oil start to rise, indicating that the bearings were starting to go. Putting in new bearings avoided the catastrophic failure that was about to occur and saved $164,000, the value of the engine minus the cost of putting in the bearings. Rebearing cost only about 12 hours of downtime compared to 88 hours if we had had to change the engine, saving another $1,140,000.

Reliability Centered Maintenance (RCM) Coordinator

In another situation, the oil of the transmission on a Caterpillar 992 loader was found to contain copper, the level of which was so high that that the core would have been ruined in another eight hours of operation. Although the transmission had to be rebuilt, preserving the core saved $78,000.

Sometimes, oil analysis can also save warranty costs. During the rebuilding of an engine, the rebuilder pulled a sample from the bottom of the pan. They detected high levels of glycol and blamed the failure on a glycol leak which would not have been covered by the warranty.

I sent the sample to our in-house lab and they said there was no glycol. For confirmation, I sent another sample to an outside lab and they also said there was no glycol. So the manufacturer covered the cost of rebuilding the engine which saved us about $150,000. For every engine we save, we pay for the cost of operating the lab for an entire year, including the depreciation on the instruments. We have already saved four engines in 18 months of operating the in-house lab, not to mention many other cases where we have had smaller but still substantial savings. The in-house lab is superior not only in providing faster results but also in providing results at a lower cost – about 12 cents per sample – which has made it possible to increase the number of samples we are able to analyze to about 50 per day. Finally, we are also saving a substantial amount of money on oil changes because the analyzers tell us exactly when an oil change is needed. With hydraulic shovels that use 1500 gallons of oil at a cost of $3 per gallon, these savings add up. All in all, in-house oil analysis has provided substantial savings in downtime, equipment repair costs and oil costs that have been paid back several times over in only 18 months.

Reliability Centered Maintenance (RCM) Coordinator

 

This information has been sourced, reviewed and adapted from materials provided by AMETEK Spectro Scientific.

For more information on this source, please visit AMETEK Spectro Scientific.

 

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