Abstract: A new process for continuously preparing granules having narrow grain size distribution, comprising a) spraying the product to be granulated in liquid form into a fluidized bed, b) separating the proportions of fine material escaping from the fluidized bed from the off-gas and returning said fine material to the fluidized bed as nuclei for granule formation, c) setting the fluidizing gas flow such that granules are formed which are of a predetermined size, and d) removing the completed granules solely by way of at least one countercurrent gravity classifier inserted into the outflow bottom of the fluidized-bed vessel. A new apparatus for carrying out the process according to the invention and new granules.

Abstract: In the process for the agglomeration of slightly soluble and hydrolytically sensitive substances, a powder of the slightly soluble substance is conducted, together with at least one water-soluble binder, in free fall through a steam atmosphere at temperatures between 85.degree. C. and 105.degree. C. essentially without the action of compacting forces. In this process, the residence time in the steam atmosphere is approximately 0.5 to 10 seconds. The agglomerates formed are then dried in free fall, so that small solid bridges form from the binder liquid bridges formed at the points of contact between the primary particles. In a following integrated fluidized-bed dryer, the final drying then takes place to a water content of less than 0.5% by weight. The process is carried out in a steam jet agglomerator in which a freely falling product curtain of the pulverulent mixture to be agglomerated is impinged by steam using steam jet nozzles (5, 6).

Abstract: In the process for the agglomeration of slightly soluble and hydrolytically sensitive substances, a powder of the slightly soluble substance is conducted, together with at least one water-soluble binder, in free fall through a steam atmosphere at temperatures between 85.degree. C. and 105.degree. C. essentially without the action of compacting forces. In this process, the residence time in the steam atmosphere is approximately 0.5 to 10 seconds. The agglomerates formed are then dried in free fall, so that small solid bridges form from the binder liquid bridges formed at the points of contact between the primary particles. In a following integrated fluidized-bed dryer, the final drying then takes place to a water content of less than 0.5% by weight. The process is carried out in a steam jet agglomerator in which a freely falling product curtain of the pulverulent mixture to be agglomerated is impinged by steam using steam jet nozzles (5, 6).

Abstract: A process for the continuous fluidized bed agglomeration of a solid in powder form, wherein the powder, a granulating liquid and propelling air are fed through a three-substance nozzle into the center of a fluidized bed to form a three-phase mixture in the center of the fluidized bed.

Abstract: Process for the continuous fluidized bed agglomeration wherein the granulating liquid together with propellant air is supplied centrally through a three-phase nozzle on the distributor of the fluidized bed, and at the same time, the solid in powder form is fed into the fluidized bed through the annular space or the three-phase nozzle with the air of a current of propellant air, supplied separately and concentrically.

Abstract: Granule production is based on particle growth in a fluidized bed (4), in which the liquid starting product is sprayed into the fluidized bed and the finished granular particle is discharged from the fluidized bed (4) with classification. The classification is carried out with the aid of a classifying air flow which is divided into individual single flows (6) to each of which is assigned a zigzag classifier module (7, 17) and a spray nozzle (5) or a group of spray nozzles. The course of the classifying process is such that the granular particles which are too small and have not yet reached the desired diameter are thrown back into the fluidized bed (4) by a return shaft (9, 18) seated on each of the zigzag classifier modules (7, 17) in parallel or radial zones without cross-mixing, in which the relatively small particles impinge at a relatively large distance from the return shaft (9, 18) and the large particles, which have already grown close to the discharge size, impinge at a relatively small distance.

Abstract: A new process for continuously preparing granules having narrow grain size distribution, comprisinga. spraying the product to be granulated in liquid form into a fluidized bed,b. separating the proportions of fine material escaping from the fluidized bed from the off-gas and returning said fine material to the fluidized bed as nuclei for granule formation,c. setting the fluidizing gas flow such that granules are formed which are of a predetermined size, andd. removing the completed granules solely by way of at least one countercurrent gravity classifier inserted into the outflow bottom of the fluidized-bed vessel.A new apparatus for carrying out the process according to the invention and new granules.

Abstract: The zigzag classifier has a classifying space provided with air inlets which is subdivided into zigzag-shaped ducts, which are connected in parallel with respect to the flow, the lengths of which are greater than their widths. In this way a classifier package is formed with a plurality of small duct cross-sections. This design principle permits substantially lower overall heights for the same number of bends.

Abstract: Polyacrylonitrile filaments having a residual solvent content of less than 5% by weight and a total linear density of over 100,000 dtex can be prepared without contact with an extracting agent for the spinning solvent by a process in which(a) the spinning solution spun has a viscosity at 100.degree. C. of 10 to 60 falling-ball seconds,(b) the filaments are treated while still hot, directly at the end of the spinning cell, inside it or immediately outside the end of the cell, with a spin-finish which contains a lubricant and an antistat and which gives the filaments a moisture content of at most 10% by weight, relative to the solids content of the fibre, and(c) the filaments are immediately exposed to a heat treatment without cooling down first.

Abstract: Ready-for-despatch filaments and fibres made of acrylonitrile polymers which contain at least 40% by weight of acrylonitrile units can be prepared from a spinning solution in a continuous dry-spinning method in which(a) the spinning solution spun has a viscosity at 100.degree. C. of 10 to 60 falling-ball seconds,(b) the evaporation of the solvent in the spinning cell is controlled in such a way that on leaving the spinning cell the solvent content of the filaments is at most 40% by weight, relative to the solids content of the fibre,(c) before the stretch the filaments are treated with a spin-finish which contains a lubricant and an antistat and gives the filaments a moisture content of at most 10% by weight, relative to the solids content of the fibre, and(d) before the stretch the filaments have no contact with any other extraction liquid for the spinning solvent.

Abstract: The invention relates to a process for continuously removing residual solvent from filaments of dry-spun acrylonitrile polymers to values of below 2% by weight of solvent by a multi-stage hot-wash with low quantities of water.