Abstract: This invention provides a method and apparatus for injecting an additive into a stream of homogenized plastics material. The apparatus includes a homogenizing means such as a screw conveyor for the plastics material and at least one injector for injecting an additive, usually a colorant, into the boundary layer only of the homogenized plastics material prior to the latter being subjected to mastication in a gear pump. The additive is injected into the plastics material at such a position in the boundary layer that as the material passes through the gear pump the additive is mixed substantially wholly with the boundary layer of plastics material and for this purpose the injection of additive is at a position such that it passes through the gear pump in the region of the intermeshing gears of the pump.

Abstract: In accordance with this invention there is provided a method of and apparatus for producing a combustible product from waste materials of which part of the fuel consists of pulverized combustible solid waste material, this part of the fuel being at least coated with combustible liquid waste.