Abstract: The invention relates to a method for drying pasty materials, in particular sludge from wastewater treatment plants, including a first indirect drying stage (1) supplied with a heat-transfer fluid, which outputs (1a, 1b) pre-dried sludge and water vapour; a step (6) of forming sludge at the outlet of the first stage, and a second stage of drying (7) pre-dried sludge that is heated by means of a heating gas, in particular air, said second stage producing (7b) dried sludge; at least one portion of the dried sludge produced by the second stage is incinerated (23) to produce thermal energy, and at least one portion of said thermal energy is used to heat the heat-transfer fluid of the first drying stage.

Abstract: On processing pasty materials, the material is conveyed with a relatively high dry fraction of 40 to 75% through the holes (62) of the perforated plate (42) of a granulator, in that a feed element (50), forming with the perforated plate (42) a wedge-shaped gap space (61), strokes with its trailing edge (53) over the perforated plate (42). The material strands (63) pressed out of the holes (62) are cut off by a knife-like separating device (64) stroking over the discharge-side surface of the perforated plate (42). Thus, particles of a particularly small size can be produced with a relatively low energy cost from the sludge and without the granulator being blocked by a damming up of fibres, e.g. in the form of hair contained in the sludge.

Abstract: On drying pasty materials, particularly sewage sludge, the material is compacted in an intermediate drying stage with a dry fraction of 60 to 80%, so that relatively low energy costs are required. The conveying of the material takes place both during pre-drying and after leaving the compactor on one or two air-permeable conveyor belts (3, 4) succeeding one another in the conveying direction and which are enclosed in a common housing (2). Thus, drying before and after compacting is performed under identical method conditions, so that it is possible to produce a simple and therefore inexpensive installation for performing the method. The finished product has advantageous characteristics with regards to density and abrasion resistance, so that dust production is avoided during subsequent handling.

Abstract: On drying pasty materials, particularly sewage sludge, the material is compacted in an intermediate drying stage with a dry fraction of 60 to 80%, so that relatively low energy costs are required. The conveying of the material takes place both during pre-drying and after leaving the compactor on one or two air-permeable conveyor belts (3, 4) succeeding one another in the conveying direction and which are enclosed in a common housing (2). Thus, drying before and after compacting is performed under identical method conditions, so that it is possible to produce a simple and therefore inexpensive installation for performing the method. The finished product has advantageous characteristics with regards to density and abrasion resistance, so that dust production is avoided during subsequent handling.

Abstract: Coal or similar carbonaceous solids are extracted by contacting the solids in an extraction zone (12) with an aqueous solution having a pH above 12.0 at a temperature between 65.degree. C. and 110.degree. C. for a period of time sufficient to remove bitumens from the coal into said aqueous solution and the extracted solids are then gasified at an elevated pressure and temperature in a fluidized bed gasification zone (60) wherein the density of the fluidized bed is maintained at a value above 160 kg/m.sup.3. In a preferred embodiment of the invention, water is removed from the aqueous solution in order to redeposit the extracted bitumens onto the solids prior to the gasification step.