With a cost-consciousness, do-it-yourself approach that has become a way of life for many competitive regional concrete suppliers, Raineri Ready-Mix in St. Louis, Mo. waged a constant battle with conveyor-belt carryback, armed with brooms and shovels.  Ultimately fed up with the arduous, wasteful and sometimes risky routine of manually removing carryback fallout, the plant cautiously agreed to try a new design of head-pulley pre-cleaner engineered for simplicity and economy, and found an immediate payoff.

      As one division of Raineri Building Materials, Inc. — a broad-line, family-owned construction supplier offering everything from concrete delivery and masonry tools to specialty plasters for medical/dental and artistic uses — the ready-mix unit serves a three-county area with two batching plants, one in St. Louis and the other in Eureka, 30 miles west.

      At the St. Louis plant, six material bunkers each hold up to 350 tons of the most frequently specified crushed stone, alluvial gravel and sands, lined up over a 265-ft. tunnel conveyor.  The tunnel belt carries batch-required quantities of these materials to an open pit for transfer onto a 147 ft. incline conveyor, which carries the materials to the top of the batching plant.  A hopper above the transfer allows front-end loaders to add various specialty materials such as colored aggregates stored in surge piles nearby.  Both belts, 30" (762mm) wide and troughed at 35 degrees, typically run at about 750 fpm.

            “Our sand and aggregates typically contain a little clay and hit the belts with four to 10 percent moisture, so they can get pretty sticky,” explains Secretary/Treasurer Chris Raineri.   “Both the tunnel and incline belts were originally installed with belt cleaners, but their design forced the cleaners to be positioned where carryback material cleaned off the...

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