Screw Feeders for Metering Limestone from Weigh Hoppers Minova in Georgetown, KY

General Description

Orica Mining Services is a multinational global leader in the provision of commercial explosives and blasting systems for the mining industry. Minova, a subsidiary of the Orica Group, is a manufacturer and supplier of products for the underground mining, construction and civil engineering industries with manufacturing facilities in more than 25 countries.

Plant engineers from the Georgetown, KY facility contacted KWS to design and supply four new inclined screw feeders. The new screw feeders were used to meter crushed limestone from weigh hoppers mounted on load cells to batch mixers. The crushed limestone is mixed with other proprietary ingredients in the production of many of Minova’s mining products.

Design Parameters

1. Product Type – Crushed Limestone
2. Material Density – 86 Lbs. per Cubic Foot
3. System Capacity – 453 Cubic Feet per Hour
4. Duty – 24 Hours per Day, 7 Days per Week

KWS Advantages

Engineers from Minova were concerned that the new screw feeders would not fit into the existing space at the plant. The KWS engineering and sales team gathered dimensional information and provided detailed design drawings and 3D models prior to the order so the engineers at Minova would be comfortable with the design. Minova provided a sample of the crushed limestone so KWS could test and observe the material’s characteristics to ensure proper inclined screw feeder design.

Special Features

Each of the four production lines was not identical and KWS had to incorporate a small surge hopper on the inlet of each inclined screw feeder. The surge hoppers were needed to handle variations in the process. The four screw feeders were designed with identical components to make keeping spare parts economical. The inlet stubs on the new screw feeders were supplied with flexible transitions so the weigh hoppers could be connected to the screw feeders and not interfere with an accurate weigh measurement.

Designing inclined screw feeders can be very difficult. After testing the crushed limestone in the KWS lab, the inclined screw feeders were designed for maximum efficiency. The screws were designed with special pitches and a close-tolerance fit to the non-split tubular housings.

The drive units were mounted on the inlet (lower) end of the incline screw feeders because of space constraints on the discharge (upper) end. KWS incorporated a bulkhead style tubular trough end and flanged gland seal on the inlet end to minimize material leakage and gearbox contamination. The flanged gland seal consists of three rings of graphite rope packing that create a positive seal around the shaft when compressed.