Lump size

When dredging rock with a cutter suction dredge, the maximum lump size is generally limited to 30-50 cm. This corresponds with the maximum spherical passage of the dredge pumps and the cutter head. 

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A suspension height, Ds, of 75 to 100 mm greater than De, or the maximum lump size, or the edge of the troughed idler in the burden is required, ie,... 

Industrial, centrifugal elevators usually operate at speeds of about 75 m /min, and handle free-flowing, fine and loose materials having lump sizes of <50 mm. Sticky material can be a problem. Fine fluidizing materials often require perforations in the bottom of the buckets to vent entrapped air. Centrifugal elevator capacities range up to 370 m /h for a single row of buckets, and up to 1400 m /h for multiple rows of buckets. The buckets can be mounted on a belt or chain. 

Material characteristics, both chemical and physical, should be considered, especially flowabihty. Abrasiveness, friability, and lump size are also important. Chemical effects (e.g., the effect of oil on rubber or of acids on metal) may dictate the structural materials out of which conveyor components are fabricated. Moisture or oxidation effects from exposure to the atmosphere may be harmful to the material being conveyed and require total enclosure of the conveyor or even an artificial atmosphere. Obviously, certain types of conveyors lend themselves to such special requirements better than others. 

Material classf Screw diam., in Max. lump size, in Capacity, oil ft/hr Approx, area occupied by material f... 

Belt selection depends on power and development of the required tensile strength. Knowing drive-shaft power, belt tension can be calculated and a belt selected. However, since various combinations of width and ply thickness will develop the required strength, final selection is influenced by lump size, troughability of the belt, and abihty of the belt to support the load between idlers. Thus it is necessaiy to use an empirical approach to arrive at a belt selection which meets all requirements. 

Belt width Cross- area sectional of load Belt speed, ft/min (m/min) Belt plies Maximum lump size, in (mm) ... 

Diam. of Con- veyor, Inches A Mai. Lump Size, Inches Maximum Recommended rS m. Capacities, Cubic Feet Per Hour At Maximum At Recommend- One ed Speed JR.P.M. Maximum Capacities, Cubic Feet Per Hour ... 

Statement 6. This is a fairly obvious comment, but it has serious implication in the selection of the slurrying time. Both the lump size and temperature vary in the feed to the slurrying unit, and the selection of an optimum time is difficult. Useful experimental data were presented by Great Canadian Oil Sands in 1967 (7). 

Available forms Standard, low-carbon, and medium-carbon grades in ground, crushed, and lump sizes ranging from 80 mesh to 75-lb lumps, suitable for ladle or furnace addition. 

House-hold and industrial waste is shredded in a hammer mill where pieces of 4 inch maximum lump size are carried by a conveyor to screens through which glass, ceramics, slag, ash and other inerts smaller than 3/8" are discarded. Pieces larger than 4" are separated by gravity. 

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