GB189905353A - Improvements in and connected with the Utilisation of Waste Sand from Glass Works. - Google Patents

Abstract

5353. Herman, D. March 11. Materials.-Relates to the utilization of sand which has been employed for grinding plate glass &c., and which, in consequence, contains both glass and iron finely diffused through it. The particles of metallic iron are removed from the sand either in the wet or dry state by the use of magnetic separators. The sand is graded, when mixed with water, by passing it through settling- pits, from which the coarser grains may be returned to the grinding-benches. The finer sand is dried in a hydro-extractor, or in a rotary furnace, or otherwise, and is then treated with hydrochloric acid or other solvent with or without the aid of heat. The recovery of the acid is effected by completely wetting the sand with the acid without using more than is required for that purpose, allowing water to run on the sand, and drawing off the acid at the bottom of the vessel. The water then takes the place of the acid, without appreciably mixing with it, and as soon as water reaches the outlet the stream is diverted. If the sand is of the very finest grade, it may be necessary to remove the solvent and washing-water by subsidence and decantation, or by a hydro-extractor, or coarse sand may be mixed with the fine sand to render it permeable. The product is well adapted for the manufacture of glass, as it already contains a considerable proportion of the finest glass.