GB1115515A - Vibratory ball mill - Google Patents

Abstract

1,115,515. Ball mills. E. W. SMITH. 17 Aug., 1965, No. 35238/65. Heading B2A. [Also in Division F2] A system for continuously grinding or batch grinding material comprises a mass 10 having a plurality of metal tubes 16 for containing the material and grinding particles, a spring means 11 connected at one end to the mass 10 and at the other end to a mass 14, the spring means 11 and masses 10, 14 forming a resonant system having a resonant frequency and vibratable with forces providing an acceleration of at least 65G, and electromagnetic means 15 for establishing the system in resonance. The resonant frequency, the stiffness of the spring means 11, and the masses 10, 14 are interrelated by the formula: where f = resonant frequency of the system u = stiffness of the spring means in dynes/cm. M' = total mass in grams to be vibrated including mass 10 and the material and grinding particles therein M" = mass 14. The mass 14 may be greater than or equal to the mass 10 and in the latter case may be a mirror image thereof. The tubes 16 are arranged in rows and columns and supported in a frame 19, the tubes being connected in series by means of end plates 21, 22 removably secured to the frame 19. A screen 30, or 31, is disposed at each end of the tubes to retain the grinding particles while allowing the ground material to pass therethrough. Openings 25 and (26) Fig. 3 (not shown) are provided for a liquid carrier. The tubes may be surrounded by heating and cooling means. The plates 21, 22 are movable along a frame 8. Alternatively, the plates may be flat and be permanently secured to the frame 19. The spring means 11 comprises a plurality of circular discs (50, 51) Fig. 3 (not shown) arranged in pairs, the peripheries of each pair being clamped together, by means of nuts and bolts (59, 60), and the outer surface of each disc having extending therefrom a threaded projection (61), adjacent pairs of projections being interconnected by internally threaded sleeves (64). The stiffness of each disc is de termined by the equation U = Et<SP>3</SP>/22R<SP>2</SP> where E = Young's modulus in dynes/cm<SP>2</SP>. t = thickness of the disc in cms. R = effective radius of the disc in cms. The electromagnetic means for establishing the system in resonance comprises four electremagnets such as 72. The electromagnet 72 comprises a pair of armatures 78a, 78b connected to the mass 10 and a pair of E-shaped stators 77a, 77b connected to the mass 14, the stators each having a coil (79) Fig. 3 (not shown) wrapped around their centre leg 80. The armatures are in the form of flat plates spaced from the legs of the" stators.