Abstract: In the process and the apparatus, a gas stream is divided into three partial gas streams. The first partial gas stream transports the material to be ground into the grinding and friction space of a mill (26), while the second partial gas stream runs around the friction space in the mill. The third partial gas stream is connected to the output side of the mill and takes up the reduced and dried ground material, transported out of the mill by the first and second partial gas streams, in order to transport it to a separator (30).

Abstract: In the process and the apparatus, a gas stream is divided into three partial gas streams. The first partial gas stream transports the material to be ground into the grinding and friction space of a mill (26), while the second partial gas stream runs around the friction space in the mill. The third partial gas stream is connected to the output side of the mill and takes up the reduced and dried ground material, transported out of the mill by the first and second partial gas streams, in order to transport it to a separator (30).

Abstract: A process and apparatus for screening cellulose ethers which have a finely fibrous or wad-like or woolly structure, wherein the process comprises the following steps:a) applying the cellulose ether (material to be screened) to a sieve surface,b) dividing the material to be screened into an screenable portion (acceptable size material or material passing through the sieve) and a circulating portion (oversize material or sieve surface tailings) with the aid of an agitated (preferably vibrating and/or tumbling) sieve surface,c) flushing through the agitated sieve surface from below, generally perpendicularly to the sieve surface, with an air flow,d) discharging (recovering) the acceptable size material, ande) discharging the circulating portion from the sieving system.The air flow inhibits clogging or plugging of or matting upon the sieve surface and is preferably directed upward by slit nozzles arranged below the sieve surface.

Abstract: The present invention relates to a process and a device for selectively separating the solvents employed in the preparation and purification of products. In this connection the different solvents are removed from the product to be treated by means of mechanical separation and subsequent admission of steam, and are collected separately. As a result of this, mixing of solvents from the preparation and from the purification is avoided, so that the working up of a solvent mixture is superfluous. The proces and the device are preferably used in the process for producing starch ethers and cellulose ethers.

Abstract: The present invention relates to a process for careful grinding and simultaneous drying of moist cellulose ether products wherein a moist cellulose ether is introduced by means of a transport gas into a circular space. The moist cellulose ether is impact-comminuted while being circulated in that space, and the product is simultaneously friction-comminuted in a direction opposite to that of the impact comminution. The peripheral speed of the comminution stages, which operate in opposite directions, is regulated to such a value that the resulting grinding energy dries the product to a predetermined residual moisture content. The ground material is conveyed by the gas stream introduced into the comminution space, and the ground material is then separated from the gas stream. If desired, the ground material is subjected to selective screening.

Abstract: A polymer hydrogel substantially free from monomers and oligomers is prepared by contacting a previously prepared polymer hydrogel with a single-phase mixture of water and a solvent and then separating the mixture of water and solvent from the hydrogel.