Grinding and processing of stone containing raw material in the manufacture of cement

摘要

1,266,328. Tube mills; grinding cement. F. L. SMIDTH & CO. A.S. 5 June, 1969 [17 Sept., 1968], No. 44097/68. Heading B2A. Apparatus for grinding and drying material in particular chalk and clay containing unwanted flints in the manufacture of cement comprises a rotating tumbling mill 7, means 4, 5, 6 to introduce raw material and means 9, 10 to introduce hot gas through the inlet trunnion of the mill, a riser pipe 12 acting as a separator with its lower end communicating with an outlet trunnion of the mill, and the upper end communicating via a cyclone 13 with the suction side of a fan 15. Atmospheric air is prevented by flexible seals from entering a casing 5 which feeds the mill 7. The exit gas from the fan 15 is cleaned by an electro-precitator 18. The product is discharged from the cyclone 13 and the filter 18 to a conveyor 24. Some of the dry fine product is however discharged from cyclone 13 via a pipe 21 and is conveyed by a belt 29 to an inlet screen 31 for the mill, where it is distributed over the sticky feed material, and thus reduces its stickiness. Coarser material separated in riser pipe 12 falls via a pressurized discharge chamber 34 on to the conveyor 29. Large unground flint bodies are rejected by the screen 31. In a second embodiment, Fig. 2 (not shown) material is predried in a pipe 38, see Fig. 3, prior to milling and two flows of dried material 28 and (48) from two cylones 39, 13 are available for distribution over the incoming sticky material. In a third embodiment an additional screen 49 is provided for material separated by the cyclone 39 and the screen residue is added to material flowing to the mill.