Personnel at Lafarge's Joppa plant in Grand Chain, Ill., visited international and North American chute manufacturers in search of the best solution for loading finished cement into barges.

After careful study and consideration, Lafarge selected the Cleveland Cascade Chute to overcome dusting problems in loading finished cement. The chute has enabled the plant to successfully load finished cement into barges within EPA guidelines.

The system at the Joppa plant features a dual Cascade Chute arrangement. The finished cement discharges from the weight bin onto dual airslides to the dual chute into open top barges. Each chute handles 300 tph, loading 600 tph into the barge.

The Cleveland Cascade Chute includes dual material probes, load cell system, pneumatic and electric hose reels, and special adapter cement skirts (Figure 1). It consists of a series of truncated, oppositely-inclined cones, supported by straps, and surrounded by an independent wind shroud.

The cones and shroud are suspended from a steel carrier by three cables and are raised and lowered as needed by a 5-hp electric motor and brake assembly. The loading chute is PLC-operated and radio-controlled. Extended, the loading chute's length is 65 ft. Its weight is less than 6,000 lb.

While material piles up during loading, the cones retract by telescoping, as needed, forming a compact nest for maximum air draft. The cones completely retract into the chute's transporter for storage and product changeover. When lifted, the carrier supports the compact stack of cones. The hoist wires perform a secondary function in the provision of guides for the wind shroud.

A specially designed steel head chute is attached to the conveyor discharge boom. It provides a support for the chute and introduces bulk material into the Cascade cones in mass flow and at the correct inclination and velocity. The chute can be removed in a few minutes, according to the makers.

The loading chute has 28 alternating-angle, cone-shaped spouts. Each cone is angled to the same degree but alternates in direction; odd cones angle left, even cones angle right. A head chute and initial cascade assembly guide product into the cascading cones. The cones are constructed of fiberglass, nylon, and corrosion-proof metals and have replaceable liners. In operation, material gently cascades through each cone for a 65-ft descent to the hold bottom.

The materials testing and calculations at the chute manufacturer's plant provided the precise cone angle needed for desired tph. The angle is extremely important: A difference of 11/42 makes a 100-tph difference.

In the chute's bottom cone are two level indicators. If the piling product fills the cone and starts choking off flow, the indicators sense it and automatically index the chute up 6 in. If the cone still retains material, the chute will continue to index the indicators report product flow.

Managers at the Joppa plant discovered the Cascade system eliminated the problem of free fall and induced air movement. The system introduces mass flow at low velocity. Mass flow maintains the bulk particles tightly packed together, thus minimizing the release of the small dust particles. As no air escapes from the discharge point, no dust escapes. According to the plant managers, the chute provides excellent dust control without fan-assisted dust extraction systems.