Cool Mining Expenses
By Bob Reed

Traditional methods of cost-cutting become very frustrating when every number has been crunched and the goal is still out of reach.  This is a common problem at almost every business.  Managers must constantly look for acceptable means of reducing expenses and investigate all the possibilities they discover.

Frank Heigert and Jim Hawk from the Monterey Coal Co., a longwall mining operation located near Carlinville, Illinois, were no different when they attended the monthly Equipment Maintenance Council meeting in Springfield.  The meetings are normally beneficial, but they didn't expect this particular meeting to have such an impact costs at the Monterey mine.  The topic of the program at the meeting concerned treating metals cryogenically to improve wear characteristics and reduce breakage, downtime, and change-outs, and by doing so, lower costs.  Cryogenics?  It was to be an innovative new topic, but those were some far-out claims.  After all, how could cryogenic treatment at -300˚F improve metal?  Not to believe everything they read, Heigert and Hawk listened to the program with an open mind.

During the program, they learned that top racing teams improve performance and reduce wear and breakage in race cars by cryogenically treating engines, transmissions, rear-ends, axles, etc.; that manufacturers have cutting tools treated to keep them sharper longer, reducing downtime and tooling purchases, and improving the bottom line; that top firearm competitors have barrels treated to improve accuracy, reduce cleaning time, and increase the life of firearms; and that there are many other applications getting the "Cryo-advantage."  After the program, Heigert and Hawk wondered if the cryogenic treatment could be used to treat problematic links and pins in the bucket system at the Monterey prep plant.

As should be the case when discussing cryogenic tempering, the material must be considered.  The material used for links and pins, manufactured by Bennett Metal Products in Mt. Vernon, was Astralloy.  At first glance, it appeared that treating the Astralloy would be a good decision.

When the bucket system is repaired, the plant has to be shut down (i.e., no coal), and change-out requires a lot of labor, making the replacement expensive.  It was decided to ship new links and pins to 300 Below, a company located in Decatur, Illinois, that

specializes in cryogenically treating metallic parts.  After the links were treated, they were installed at the Monterey prep plant and testing began.  During the test, the treated links and pins surpassed the normal life of untreated links and pins and continued to perform.  When they were finally replaced, there had been a tremendous gain.  Monterey decided that in the future, all links and pins would definitely be cryogenically treated.  The bucket systems at Monterey are now operating entirely with cryogenically treated links and pins and getting a 50% gain on the primary side of the bucket system, and those on the secondary side of the bucket system are consistently lasting 100% longer.  Monterey understands that the cryogenic treatment is very affordable, gives them less downtime, more through-put, the need to purchase fewer links and pins, and most important of all... they save money.

Cryogenics is unique in that it goes against something most Americans demand-- a visual.  Cryogenically treated parts cannot be identified visually or by the touch.  It would take a high-powered microscope to find even the slightest change.  It's not until treated parts are installed that improvements are noticed.  It becomes very apparent that treated parts last longer and impact finally begins to hit home.

If you can't see of feel the changes following cryogenic treatment, the question remains, "Why does cryogenics work?"  Since we don't have the luxury of saying, "Look at the difference," we have to explain the change as best we can, based on the tremendous improvement that is occurring.

One should think of the metal that has not been cryogenically treated as being open-grained, much like spreading the fingers on one's hand.  The grain structure would then be described as open-grained.  After being treated, the metal is closed-grained, much like squeezing one's fingers together.  The grain structure of the treated metal is described as closed.  With the voids closed, the treated metal is stronger and more abrasion resistant, and therefore, lasts longer and required fewer replacements.

In tyhe Monterey application, cryogenic treatment worked well and there are other areas of the mine where it could also have an impact.  Transmissions are made of cases, gears, shafts, bearings, and forks and so are gear drives and transfer cases found throughout the mine.  Crushers, feeders, loaders, dozers, graders, continuous miners, and longwall machines have integral parts that are prime candidates for cryogenic treatment.  Cryogenically treating brake rotors and drums normally results in an improvement in brake life of 250% to 400%.

The links and pins at Monterey are just the tip of the iceberg.  As more mines and plants become more familiar to cryogenic treatment, mine operators may see pesky downtime problems from high-wear areas dissipate.  Not everything can be fixed with cryogenic treatment, but by identifying and treating those applications that will likely respond, the all-important bottom line can show vast improvement.