Secrets to a longer life
November 1, 2007 By: Rodney E. Garrett Pit & QuarryA manufactured sand producer in Tennessee finds that using the right jaw-crusher wear parts saves time and money in the long run.
Highland Sand Co. in Crab Orchard, Tenn., produces manufactured sand at its quarry operation. The site produces only manufactured sand, with screened out fines sold as masonry sand.
 Jim Rivers, left, began Highland Sand Co. along with his brother Arthur in 1972. |
Typical quarries necessitate multiples of crushers and screens with primary, secondary, tertiary and sometimes even quaternary plants in place for producing a list of aggregates products.
At the Highland Sand quarry, the complete plant is designed for producing the one product and while the production part is straightforward compared with multi-aggregates production, the company has had its challenges concerning the cost for wear parts. The high cost was not so much associated with the purchase price of the wear parts but the total usage cost owing to their short lifespan.
The concern of increasing crusher wear parts life is on the minds of most managers that are involved with manufacturing sand.
While the physical attributes of sand make it ideal for using as aggregates in ready-mix concrete and asphalt paving products, sand is very abrasive and relatively hard. It is thus prudent for the sand manufacturer to investigate all possible avenues for increasing wear-parts life on its crushing and screening equipment.
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Investigating is just what the Highland Sand Co. did and with results that more than paid for the effort in seeking better wear parts.
Its success circles around the wear parts changes made to two of its jaw crushers. Here is some background on the company and its operation that led to solving the wear parts cost problems.
All in the family
The company was established in 1972 by brothers Jim and Arthur Rivers. Actually, their father bought the 140-acre tract at an earlier date with his intention to develop it into a quarry, but it never materialized. Prior to the quarry business, the brothers were operating a concrete masonry block and a ready-mix concrete company, so their knowledge of aggregates from a usage perspective in producing ready-mix concrete was already extensive. Most important, they knew what constitutes good-quality aggregates.
In order to hold capital costs low, Jim and Arthur decided to purchase used crushing and screening equipment and do most of the installation themselves. One of the company's main equipment suppliers, Southern Machinery Co., Nashville, Tenn., designed the plant and gave them advice on how to put the plant together. Finally, the plant went online in 1974, processing 30,000 tons of sand that was sold the same year.
The rock quarried is sandstone with 94 percent silica (SiO2) content. Mining is carried out by drilling pre-designed blasthole patterns and blasting with specified explosives quantities to get rock fragmentation as close to 24-in. minus as possible. Most faces in the multi-bench quarry are about 50 ft. high. One shot yields about 25,000 to 30,000 tons of blasted rock. Highland Sand contracts the blasthole drilling, loading of explosives and blasting. Jim Rivers, now the sole owner of the company, says at one time the company did its own blasting, but with the new stringent government rules involved in handling explosives, they opted to use the services of a contractor.
Today, the blasted rock at the face is loaded onto a 35-ton capacity Caterpillar off-road hauler using a John Deere front-end loader. The blasted rock is hauled to the primary jaw crusher, which is a Pioneer 24x36. All rock is dumped into a grizzly where the rock pieces 24-in. minus are scalped from the fines that would have a tendency to cause an extreme abrasive/binding action on the jaw crusher's wear parts, according to Ronnie Snow, plant superintendent
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