METHOD OF PURIFYING SILICA CONTAINING SEWAGE TO REMOVE HEAVY METAL IONS Russian patent published in 1999 - IPC

FIELD: chemical industry. SUBSTANCE: in order to carry method into effect, acid is first added to the solution to be purified to pH of more or equal to 2.5 alkali reagent is then added to pH values optimum for settling heavy metal ions. If desired, silicic acid or its salts are added to the solutions to be purified. In some cases aluminium III compounds are added to the solution to be purified at SiO₂:Al₂O₃ weight ratio of 6:1. Method makes it possible to create optimum conditions for purifying silica flows to remove metals due to internal reserves of the system to be purified. EFFECT: more efficient purification method. 1 dwg, 5 tbl