METHOD OF CLEANING OFF-GASES FROM CHLORINE AND SULFUR OXIDE TO OBTAIN BINDER Russian patent published in 2020 - IPC B01D3/14 B01D53/14 

FIELD: chemistry.

SUBSTANCE: invention relates to cleaning of toxic impurities of pyrolysis gas and other offgas to obtain high quality of binding agents - bischofite and bitter salt. Method of cleaning off-gases from oxides of sulphur and chlorine to obtain binder includes continuous contact of gases in an absorption scrubber with circulating water absorbent in form of an aqueous suspension of dolomite dust, supplied from the container. Purified gas from scrubber is fed into gasholder. Spent suspension from the reservoir is directed for processing and obtaining binder by successive separation into solid and liquid phases. Suspension is prepared using dolomite dust containing 88.5 wt. % of magnesium oxide. Analysed and adjusted to solubility in water at temperature of 20 °C is a method for adding sulphuric and hydrochloric acid. Then, crystalline hydrates of magnesium chloride are formed in vacuum crystallizer in said suspension, which are separated on a centrifuge and dried at 100–110 °C is then ground to particle size of 200–250 mcm. High quality bischofite is obtained. Separated filtrate is directed into vacuum crystallizer, where at temperature of 20–48 °C forms magnesium sulphate crystalline hydrate. It is separated from suspension by centrifuge, dried at temperature 100–110 °C and simultaneously milled to particle size of 250–300 mcm in a combined drier of the fluidised bed. Obtained binder - bitter salt. Filtrate is used in reverse cycle when making dolomite suspension.

EFFECT: invention provides purification of waste and pyrolysis gases not only from sulphur oxides, but also from chlorine, and also provides high quality of binding agents - bischofite and bitter salt, based on which it is possible to obtain high-quality construction products.

1 cl, 1 dwg, 3 tbl