Abstract: A method of removing particulates and sulfur oxides from a hot gas by controllably contacting the hot gas in a first spray-dryer zone with a selected chemically reactive absorbent for the sulfur oxides and then sequentially contacting the hot gas with the absorbent in a second fabric filter zone. The preferred absorbents are calcium oxide, calcium hydroxide, sodium carbonate, sodium bicarbonate and sodium hydroxide. The selected absorbent dissolved or dispersed in an aqueous medium is controllably introduced into the spray dryer, together with the hot gas, in an amount and at a rate to react in the spray dryer with only a portion of the sulfur oxides in the hot gas to produce a dry particulate reaction product consisting of calcium or sodium sulfites and sulfates, together with sufficient unreacted absorbent of enhanced reactivity for subsequent reaction in the second zone with the remaining sulfur oxides, all being entrained in a substantially water-unsaturated gas of reduced sulfur oxide content.

Abstract: A process for the recovery of copper or lead from a sulfide ore concentrate containing the same. The ore concentrate, a carbonaceous material, an alkali metal carbonate and gaseous oxygen are introduced into a reaction zone to form a reaction mixture. The amount of carbonaceous material introduced is sufficient to reduce all of the copper or lead constituent of the sulfide ore to its elemental state in a single stage. A sufficient excess of carbonaceous material is provided to react with the oxygen and generate heat in situ to maintain the reaction zone at a temperature of from about 600.degree. to 1350.degree. C. thereby causing reduction of the metal sulfide to substantially pure copper or lead for recovery. The sulfur constituents of the ore react with the alkali metal carbonate to form sulfides. The other metal constituents of the ore are retained in the molten reaction mixture.

Abstract: A method is shown for removing sulfur dioxide from a hot flue gas by absorption of the sulfur dioxide in an aqueous solution or slurry containing no more than 40 wt.% of an alkali metal carbonate or bicarbonate, preferably sodium carbonate and/or sodium bicarbonate using a spray-dryer scrubber to produce a dry mixture of sodium sulfite, sodium sulfate, and sodium carbonate and/or bicarbonate. Such a mixture is directly suitable as a feed to a regeneration stage.It is particularly preferred to regenerate the absorbent and recover commercial sulfur values in a closed-cycle process by next treating the solid absorption product in a molten salt reduction step with a reducing agent, preferably a carbonaceous material, to reduce the sodium sulfite and sulfate to sodium sulfide. Concurrently, a source of oxygen is fed to the reducer to generate sufficient heat therein for the reduction step by a combustion reaction.