| 摘要 |
1,102,213. Pneumatic separation; mixing appliances. A. SCHELLENBERG. 22 Jan., 1965 [24 Jan., 1964], No. 2855/65. Headings BIC and B2H. [Also in Division F4] In the preparation of road surfacing material, the mineral components are deposited on to a conveyor belt 2 from dosing devices 3 in predetermined proportions so as to obtain a preliminary granular mixture having the desired composition as regards the coarsegrained components. The mixture is fed by the belt 2 into a rotary drier 1 having conveyor blades 12 at its inlet and outlet and blades 13 for lifting and scattering the mixture material into a hot gas flow generated by a burner 15 associated with a blower. The drier 1 is slightly inclined to cause the mixture to travel through it as it rotates. Mounted adjacent the outlet end of the drier is a sifting device comprising a streamlined body 16, a sheet metal guide 18 and a suction funnel 17. As the material falls in the drier after being lifted by the blades 13, the fine components are entrained by the gas flow through the funnel 17 while the heavier coarse components are discharged through a hood 14. The body 16 serves to increase the gas velocity near the outlet end of the drier thereby assisting the separation of the fine components. The sifting device may be situated outside the drier. The gas flow may be passed in counter-current to the granular mixture. The fine components and the gases are then passed through a coarse separator 41 where the fine sand (0.1-1 mm) is separated out and through a fine separator 42 where the dust (0-0.1 mm) is eliminated from the gases which are discharged to a stack via a fan 40. The sand and dust are returned in accurately predetermined proportions via dosing devices (not shown) to the remainder of the mixture to form a final mineral mixture which is measured into a mixer together with an appropriate quantity of a binder such as bitumen. |
