Abstract: A generator for dynamic loading of a mine lining simulates an unstable ground structure, such as a "bump" of the formation roof by an explosion of an explosive. The generator /3/ comprises a cylinder /6/ with a piston /7/, the said piston functioning as a percussion member. The bottom of the cylinder /6/ is provided with symmetrical chambers /10/ to place an explosive. The explosive is batched to each of chambers /10/ through holes /8, 9/ made in the flank of the cylinder /6/. Holes /8, 9/ are bored at an angle enabling gravitational filling of the chamber /10/ with an explosive already after initial spragging of the lining section /1/ under test between the floor /2/ and the generator /3/ abutting the roof /5/ of the test-stand. The cylinder /6/ is closed with a limiter /12/ of the stroke of the piston. Between the piston /7/ and the limiter /12/ of its stroke there is a shock-absorbing washer /13/. In the limiter /12/ there are additional holes for release of powder gases.

Abstract: The invention relates to a dehydrating centrifugal sieve of small overall dimensions, small weight and big yield. The sieve is appropriated for dehydration, de-sludging, enrichment and classification of mineral grains.The sieve according to the invention has in a common housing (1) several conical sieve elements (2), (12), (13) disposed successively under each other and at the same time inside each other. Between particular sieve elements there are funnels (4) terminated at the bottom with a circumferential gutter (5). The circumferential gutter (5) is connected by pipe passages (6) situated in an offtake (7) of granular concentrate through a flow-off surface (9) with an offtake (10) of clarified liquid.