Abstract: The invention relates to a method for manufacturing cement clinker whereby the raw meal is initially subjected to preparatory processing, e.g. by comminution, homogenization and/or drying, and, eventually, nodulized and burned, with the nodulization process itself taking place in a stationary burning reactor. By the method according to the invention a sulphatic compound is added to the raw meal in a sufficient quantity before introducing the raw meal into the stationary burning reactor or directly into the stationary reactor, e.g. through the combustion air or together with the fuel. The sulphatic compound may be selected among all types of sulphates which will not affect the properties of the finished cement. It is particularly advantageous to use calcium sulphate, either naturally occurring or industrial by-products and regular waste materials, e.g. used absorbent from dry exhaust gas desulphurization.

Abstract: In a method for cleaning of flue gas derived from waste incineration, of the kind which comprises spray drying a lime slurry in the hot flue gas, the amount of active lime used is from 1.5 to 2.5 times larger than the amount reacting with the acidic components of the flue gas; furthermore, ground blast-furnace slag is incorporated in the lime slurry in an amount that is equivalent to 30 to 100% by weight of the amount of calcium salts generated at the flue gas cleaning. An end-product is hereby obtained, which upon admixing with water, forms a concrete-like material with high mechanical strength and great ability to retain the pollutants present therein so that the product is suited for disposal in nature with a minimum risk of polluting water streams and ground water.

Abstract: A dry particulate sulfite-containing material produced in a flue gas desulfurization process is oxidized and agglomerated in a fluidized bed reactor, wherein the material is fluidized in an oxygen-containing gas. The oxygen-containing gas which is supplied to the fluidized bed has a temperature below the agglomeration temperature of said particulate material. Due to the exothermic character of the oxidation, the temperature of the fluidized bed is maintained above the agglomeration temperature of the particulate material. Gas with entrained particles leaving the fluidzed bed are cooled during its passing through the freeboard of the fluidized bed reactor, whereby problems due to sticking of said entrained particles are avoided. At least a part of said entrained particles are recycled to the fluidized bed reactor.A fluidized bed reactor is provided suitable for performing the combined oxidation and agglomeration.

Abstract: Spent absorbents resulting from desulfurization of flue gas in a spray drying-absorption process contain substantial amounts of sulfite, e.g. calcium sulfite. Said sulfite is oxidized into sulfate by heating of the spent absorbent in the presence of an oxygen-containing gas, preferably at temperatures of 350.degree.-600.degree. C. Thereby the spent absorbents may be converted into materials having industrial utility.

Abstract: A calcium sulfate anhydrite material is prepared from a spent absorbent resulting from desulfurization of flue gases. First the sulfite in the spent absorbent is oxidized into sulfate, preferably by heating in an oxygen containing gas, and thereafter the chloride content of the spent absorbent is reduced by heating the spent absorbent at a temperature of 600.degree.-950.degree., preferably 750.degree.-950.degree. C. together with fly ash. Said fly ash may be recovered together with the spent absorbent in the desulfurization process, or it may have been recovered separately and mixed with the spent absorbent.The product may be used as cement additive or for other purposes in which calcium sulfate anhydrite is conventionally utilized.