Operation Cuts Downtime and Costs with Long-Wearing Idlers
Shale is the most abundant sedimentary rock in the world. Formed from the compaction of silt and clay-size mineral particles, shale is often called a “mudstone,” and is described as being “laminated” or made up of many thin layers. The Expanded Shale & Clay (ES&C) group at Texas Industries, Inc. (TXI) is one of the largest producers of rotary kiln expanded shale and clay lightweight aggregate in North America, and is the largest supplier of this material west of the Mississippi River. For more than 100 years, ES&C lightweight aggregates have been used in applications that require strength without excessive weight – projects that include highway surfacing, concrete bridge decks, high-rise buildings, masonry, soil amendment and more.
The TXI Streetman ESC Plant is located near Corsicana, Texas, which is about 65 miles south of Dallas. Plant Manager Wynne Stallcop says that many in the aggregate industry know about his plant, “but few truly understand our processes.” He describes the plant as “a hybrid facility” as it operates crushing and screening circuits, but it also operates a kiln. After shale is excavated, crushed and screened into various sizes, particles are fired in the rotary kiln at temperatures exceeding 2000˚ F. At these extreme temperatures, gasses form tiny air cells within the aggregate. A hard vitreous membrane, consisting mainly of silica and alumina, surrounds each air cell. The glowing red-hot aggregate is then discharged into a cooling container, followed by screening and storage in various product stockpiles.
Stallcop says that the plant has more conveyor belting than the typical aggregate plant. “We have more than 15,000 feet or about three miles of belting. We maintain about 3,800 troughing idlers and those are just the 35-degree, five-can idler rolls. With the normal friction of the belt, or with material buildup, we were wearing out cans left and right. I could literally have a team doing nothing else but replacing idler rolls during each shift,” he says, adding that he started pressing his maintenance team for ideas on what could be done to extend idler life.
“We needed idlers that would give us significantly more wear life, because we wanted to reduce maintenance labor. Importantly, when idlers fail, you have the potential of tearing up the belt – and you have the downtime, the housekeeping and all the other costly situations that occur when the belt is not running,” says Stallcop.
Local equipment dealer McCourt & Sons Equipment recommended that the facility try the use of Moxie® Rolls, which are designed and manufactured by Superior Industries. “As a test, we started placing them in high wear, high traffic areas, and we found that they delivered more than 4-times the wear life of other idlers we had used previously. For me, it was a no-brainer to expand their usage throughout the operation,” says Stallcop.