Abstract: An improved roller press for the high pressure interparticle crushing of a pulverulent material and the method of operating including opposed parallel horizontal crushing rollers forming a high pressure crushing nip between them and forcing air from the material drawn into the nip, a product delivery stack above the nip and an offset lower wall portion above the nip and laterally of the stack forming an exposed sloping surface of the material for the escape of air being pressed out of the material passing into the nip, in one form exposed surfaces are on both sides of the nip and the exposed surfaces may be controlled by adjustable gates to vary the area and slope of the exposed surface, and a subatmospheric pressure may be applied to the material for aiding in the pressing of air from the material drawn into the nip.

Abstract: A process is provided for producing dry calcium hydroxide by slaking finely divided or ground, softly burnt lime by carrying out the blending of slaking liquid consisting of 30 to 50 parts by volume water and 70 to 50 parts by volume organic solvent with the lime at a temperature below 45.degree. C. in a mixing vessel, subsequently transferring the reaction mixture into a main reaction vessel where the mixture is heated by means of a heating device to a temperature of from 50.degree. to 70.degree. C., and carrying out the final reaction in another reaction vessel. In the mixing vessel, the ratio of lime to slaking liquid is selected in a way such that a final reaction temperature of 85.degree. to 110.degree. C. is reached in the final reaction vessel.