COMPLEX PROCESSING OF COAL COMBUSTION FLUE ASH Russian patent published in 2013 - IPC B09B3/00 B82B3/00 C01F7/74 C01F17/00 

FIELD: process engineering.

SUBSTANCE: invention relates to processing of wastes, particularly, to ash-and-slag wastes of thermal electric power stations. Coal combustion ash is placed in reaction zone to add carbon sorbent thereto in amount of 10-25 kg per ton of ash. Then, it is processed by the mix of ammonium fluoride and sulfuric acid, heated to 120-125°C and held thereat for 30-40 minutes. Tetrafluorosilane resulted from said processing is absorbed by ammonium fluoride. Solution of ammonium hydroxide is introduced into that of ammonium tetrafluorosilicate to precipitation of silicon dioxide. Then, concentrated sulfuric acid in double surplus is added to aluminium residue, held at 250°C for 1.5 h and processed by water. Solid residue is calcined at 800°C.

EFFECT: production of highly-dispersed silicon dioxide, aluminium sulphate, concentrate of rare and rare-earth elements.

2 cl, 6 tbl, 2 ex