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Maintenance-Free Tube Feeder System Reduces Waste, Dust Issues at Lime Plant

September 9, 2011

Lime and limestone products are among the oldest materials used for a wide variety of applications. Today, these products serve as an essential building block in virtually every industrial process. For Graymont, a leading producer of these products, that means a customer base that crosses into such diverse industries as environmental remediation, steel, pulp and paper, mining, power generation, agriculture, construction materials, chemical and waste treatment, and more.

As the third largest producer of lime in North America, Graymont is committed to efficient production and to responsibly meeting society’s need for its products by controlling the impact of its operations on the environment. Graymont makes a conscious and ongoing effort to protect the health and safety of its employees, visitors to its sites, and the people in surrounding communities.

In all aspects of its operations, Graymont strives to not only reduce waste, but to identify and prevent hazards, as well. At its Cricket Mountain Plant in Utah, the company ran across a problem that had negative potential in both areas.

The environment in which the plant is located and the nature of some of its products create conditions where controlling dust is critical. In this case, the plant had a belt conveyor that transported minus 1/8-in.-sized quick lime from two screens to an elevator, to be lifted to a product storage silo. It was discovered that they were spending at least four man-hours each week just to sweep and shovel the “carryback” from the conveyor.

The dust problem also affected production, since dust continually built up in the conveyor’s webbing and moving parts, contributing to checking and wear of the belt.

The carryback, which was discarded as unusable, amounted to about five tons per week. Graymont tried using belt scrapers, but they didn’t hold up under the adverse conditions. The company also tried an air knife, but it proved to be ineffective, and used expensive plant compressed air as well. It was then that Graymont considered that it already had a Vibra Screw vibrating tube feeder in operation for a similar application.

The Vibra Screw tube feeder, which had been installed many years previous, had been so effective that it was basically forgotten. It literally ran day in and day out with so few problems, that it grew to be taken for granted.

Graymont contacted Vibra Screw, asking the company to spec and quote a new tube feeder to replace the belt conveyor in question. With hands-on engineering support from Vibra Screw, a vibrating tube feeder system was soon installed. It eliminated dust and reduced carryback and the need for maintenance.

The unit consists of a sealed tube mounted with two rotary vibrators and supported on special elastomer isolators. There are no internal moving parts and the unit is totally sealed. In operation, applied vibration moves material along the tube surface, from inlet to outlet. Inlet and outlet seals provide a dust-free interface with the rest of the production process.

The new Vibra Screw tube feeder provided material conveying without the carryback and without the need for frequent belt replacement associated with a belt-type conveyor. Additionally, because the tube feeder is totally enclosed, it greatly reduced the overall need for dust collection and control. These advantages have allowed Graymont to keep nearly five tons of lime per week in the product stream as salable material, while freeing up man-hours that could be used to enhance production rather than performing maintenance and housekeeping.

For more information, contact Vibra Screw Inc. (Totowa, NJ) at 973-256-7410 or www.vibrascrew.com.