GB245092A - Improvements in or relating to the production of base-exchange substances - Google Patents

Abstract

245,092. Coehrane Corporation, (Assignees of Rode, S. Dahl-). Dec. 23, 1924, [Convention date]. Double silicates.-A base exchanging substance is produced by treating blast-furnace or other slag containing an alkaline earth aluminium silicate, with a strong caustic soda solution. The slag may be granulated by treatment with water and then ground in a ball mill, the ground product being delivered from a hopper 1 into a chamber T having an agitator 2. Alkali hydrate or carbonate solution is admitted at 4, heating being continued until the mixture is dry, the product being pieces about the size of hazel-nuts and smaller. The product is preferably further treated to recover a portion of the alkali and obtain a refined product. For this purpose it is delivered to a hopper 6 from which it passes to a sifter 7. The fine material, passing through a 40-mesh screen, is delivered to a vessel 9 and returned to the vessel T by a hopper 10. The large pieces, retained by a 20-mesh screen, are passed to a hopper 12 and thence to a crusher 13 from which they are returned to the hopper 6. The granules retained by the 40-mesh but passing the 20-mesh screen are delivered to a vessel 8 from which they pass to a leaching vessel 16 in which they are treated with hot water from a tank 20, the solution being discharged to a store tank 17 from which it is passed to the vessel T for mixing with the next charge. The granular material is then further washed with hot water, then with a weak solution of an inorganic or organic acid such as sulphuric or acetic acid for removing remaining free alkali and alkaline earth compounds, then with water, and then with alkali chloride solution to replace the remaining calcium in the double silicate with alkali. The product is then discharged into a draining box 23. The various washing-liquors are supplied in succession from the tank 20 and pump 21.