GB404608A - Process of and apparatus for measuring reduction in size of solids - Google Patents

Abstract

404,608. Testing physical qualities of materials. BABCOCK & WILCOX, Ltd., Babcock House, Farringdon Street, London.- (Assignees of Hardgrove, R. M. ; 719, Highland Avenue, Westfield, New Jersey, U.S.A.) April 8, 1932, No. 10156. Convention date, April 8, 1931. [Class 106 (ii).] A process for determining the grindability of a material consists in selecting a definite weight thereof divided to a given fineness, subjecting it to a definite process of pulverization in apparatus adapted to perform a precisely determined amount of work upon it and comparing the result with that obtained by submitting a standard material to the same series of steps. The factor so obtained may be used in designing a mill to fulfil given requirements. A quantity of the material under test, of given fineness may be obtained by grinding the material in a coffee mill and selecting that part of the product which passes through a sieve of given mesh but not through one of smaller mesh.. A known weight of this is then subjected to a definite process of pulverization. This may be done in the pestle and mortar device shown in Fig. 2, in which the pestle 21 is connected by links 22, 28 to a disc 30 which is rotated by a motor 31 whereby the pestle is raised and dropped through a definite stroke. A link 26 imparts a swinging motion to the pestle so that it strikes the mortar at different points. After being subjected to a determined number of strokes the pulverized material is passed through a series of sieves of progressively increasing fineness of mesh and the weight of material that passes through each sieve is noted and from these facts is deduced a number that is proportional to the total amount of new surface produced by the pulverization. An equal weight of the standard material of equal initial fineness is treated to an identical pulverizing and screening process and the corresponding number that is proportional to the new surface produced in this case is deduced. The ratio of these two numbers gives the grindability of the material under test. The materials may be pulverized in a ball-mill instead of the pestle and mortar. In this case the balls are subject to a definite pressure by a spring or weight and the mill is driven the same number of revolutions for the two materials.