GB200021A - Improvements in ball and tube mills of the multiple compartment type - Google Patents

Abstract

200,021. Smidth & Co., Ltd., F. L., (Smidth & Co., F. L.). Nov. 8, 1922. Ball and like mills.-In a ball or tube mill having two or more grinding-compartments through which the material passes, one or more screening-compartments each comprising a number of interconnected annular screening-spaces are arranged between the grinding- compartments. As shown in Fig. 1, the cylindrical screening-compartment 5 disposed between the grinding-compartments 2, 3 is provided with radial screening-surfaces 6, through which the fine material passes into an annular space 12 inside the shell 1 of the mill. Conveying-members 13 within the space 12 deliver the material into a space 14 at the end of the chamber 5. whence it passes by way of a central opening 15 into the grinding-compartment 3. The material retained in the chamber 5 is ground by grinding-bodies 17. The chamber 5 is formed by a number of double-walled screening-cages 18 with radial screening-surfaces 6, and may be adjustable longitudinally to vary the volumes of the grinding-compartments adjacent its ends. Fig. 2 shows a modification in which the screening- compartment 5 is annular and surrounds the grinding-compartments 3. The ground material passes from the grinding-compartment 2 through grates in the end wall 21 into a space 23 and thence into the screening-compartment 5. The finer particles pass through the screens 6 into the annular space 24 and thence through openings 26 into a double vane 28, one set of vanes discharging into the grinding-compartment 29 and the other set returning the coarse material to the compartment 3 for further grinding. The material ground in the compartment 3 passes through the screen 22 into the compartment 5. In another arrangement, Fig. 3, the annular screening-compartment 5 surrounds a portion of a progressively operating grinding-compartment 2, the rear portion 35 of which is separated from the remaining portion by a double wall 36, 37 having openings 38 for the passage of the grinding-bodies 4 and vanes for conveying the material retained in the compartment 5 back into the compartment 2 for re-grinding. The material passes from the compartment 2 through the grating 41 of the chamber 35 into the screening-compartment 5, from which the pipes pass by the chamber 24 and vane 28 into the grinding-compartment.