A. Abutment In coal mining, (1) the weight of the rocks above a narrow roadway is transferred to the solid coal along the sides, which act as abutments of the arch of strata spanning the roadway; and (2) the weight of the rocks over a longwall face is transferred to the front abutment, that is, the solid coal ahead of the face and the back abutment, that is, the settled packs behind the face.

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HSN code 8460 Machinetools for deburring, sharpening, grinding, honing, lapping, polishing or otherwise finishing metal, or cermet's. by means of grinding stones, abrasives or polishing. products, other than gear cutting, gear grinding or gear. finishing machines of heading 8461 Flatsurface grinding .

A road to allow access for equipment spirals down the interior slopes of the pit. ... clay, and a variety of noncopper bearing minerals. ... The mixture of ore and water is further broken up in two ball mills, which are like a rod mill except steel balls are used instead of rods. The slurry of finely ground ore that emerges from the final ball ...

3635 Gear Mfg. or Grinding. 3638 Ball or Roller Bearing Mfg. 3638 Roller or Ball Bearing Mfg. 3642 Battery Mfg.—Dry. 3643 Electric Power or Transmission Equipment Mfg. 3643 Sewing Machines—Commercial—Repairing and Rebuilding Electric Motors. 3647 Battery Mfg.—Storage. 3648 Automotive—Lighting, Ignition, or Starting Apparatus Mfg. NOC

May 19, 2016 · To make the dragging less time consuming, use appropriate equipment that is easy to hook up and adjust to conditions. Figure 7. Equipment will be needed for frequent conditioning of the riding surface to redistribute footing for an even coverage of the base material and, in some cases, to loosen compacted surface materials.