Abstract: The rolls of high-pressure roll presses for the compressive size reduction of granular material are hard surfaced with nub pins which are wear-resistant and suitable for autogenous wear protection. The nub pins, which have a long potential service life even under the action of high compressive loads, have a radially inner pin part (13) which is easily welded to the roll surface (12) and a radially outer harder pin part (14) protectively covering the radially inner pin part.

Abstract: A high pressure roller press formed between opposed cylindrical rollers mounted to perform interparticle crushing or product bed comminution in the nip and having pockets in the surface of a size to retain compressed fine grained material which is pressed in the nip with the compressed material in the pockets being retained for full revolutions of the rollers and coacting with hard portions between the pockets to form the product bed comminution against material passing through the nip and drawing material into the nip.

Abstract: Method and apparatus for calcining fine-grained material such as in the manufacture of cement in which the raw material is subjected to the sequential steps of pre-heating, calcining and sintering. At least one of the stages is fueled by coal dust which has been ground and dried with a drying exhaust gas derived from one of the stages. In accordance with the invention, an exhaust gas fraction is withdrawn from one of the stages, and has a relatively high concentration of injurious substances such as alkalis and sulfur. This withdrawn exhaust gas fraction is then cooled by one of a variety of methods, and then treated for the removal of the injurious substances. Finally, the cooled gas fraction is used to dry the coal dust fuel by conserving energy which would otherwise be lost in the process.

Abstract: A dryer system, such as is used in a pulverizing mill assembly, includes a hot gas generator which supplies drying gas to the starting point for a gas circulation system. The drying gas passes through the circulation system commingling with particles to be dried. The dried particles are removed whereupon the system gas flow is divided into a return portion and a spent portion for expulsion to ambient. Part of the system return flow is further freed of particles, compressed, and supplied to the hot gas generator as secondary gas. The return gas flow into the generator is regulated to control hot gas temperature in response to generator flow temperature. In addition, hot gas temperature may be controlled in response to system gas temperature by regulation of fresh primary air flow to the generator. Exhaust gases from the hot gas generator are introduced into the system return flow at the circulation starting point to repeat the process.

Abstract: A method is provided for adjusting or setting a definite position of rest of a rotary tube, particularly of a tube mill, by switching off the drive of the tube and is particularly characterized in that, at a time T.sub.o, the angular position of the rotary tube, or of a drive part rotating with a tube, referred to a plane of comparison is established, that the idling movement of the tube is predetermined between disconnection and final standstill, and the angular position of the rotary tube and/or of the time T.sub.x at which the drive is disconnected is calculated and effected.

Abstract: Method and apparatus for operating a process in which combustible solid particles are mixed during processing with air and circulated through a plurality of stages, thereby tending to build up an oxygen enriched combustible mixture during shutdown, the invention involving adding additional fuel to the oxygen enriched combustible mixture during such shutdown in a closed burner system, burning the resulting mixture in the closed burner system, and recirculating the flue gas from such combustion back into the plurality of stages to thereby function as an inert gas to prevent accidental combustion or explosion.

Abstract: A method and apparatus for the preparation of coaldust for use with a preheater and a cement calcination apparatus. Exhaust gas from the preheater is mixed with a source of coal and input to a pulverizing mill. The output of the pulverizing mill passes through an air current separator and a cyclone separator. The output of the air-current-separator, a stream of coal gravel, is supplied as a fuel at a calcination point in the calcination apparatus. The exhaust output from the separator provides an input to the cyclone separator which separates coaldust from the gas. The exhaust from the cyclone separator is in part fed-back to a calcination point in the calcination apparatus and is also a part of the stream of gravel. The entire process is closed so that no burnable coaldust is lost to the atmosphere.

Abstract: An apparatus and method for the safe preparation of pulverized coal comprises the steps of mixing coal with an inert gas in a pulverizing mill, separating dry coal dust from an exhaust gas bearing a residue of coal dust in a separator, mixing the exhaust gas with additional inert gas and filtering the coal dust from the gas mixture in a filter.