Abstract: A spray dryer apparatus is used to bring a water solution or slurry of finely-divided, basic reactant into intimate contact with a flue gas bearing acidic gases or vapors. The basic material reacts with the acids in the flue gas to form a particulate precipitate, while the water from the solution or slurry is fully evaporated in the gas stream. Conventional means are then utilized to remove the particulate reaction product from the flowing gas stream.

Abstract: A process for the production of high purity iron sulfate monohydrate from an iron sulfide mineral feed involving a leaching, purification, crystallization and dehydration procedure to recover a solution of iron sulfate containing iron sulfate polyhydrates and to convert iron sulfate polyhydrates in a series of steps to monohydrate crystals. The process can be also advantageously used with iron sulfide feed materials containing non-ferrous metals with full separation and recovery of the non-ferrous metals in the sulfide residue of the leaching and purification process of this invention. It can also be used for the purification of industrial pickle liquor solutions which can be treated with the iron sulfide mineral feed in this process leach circuit with full recovery of the ferrous and non-ferrous metals content of these solutions.