GB191502048A - Improvements in the Production of Aluminous Compounds. - Google Patents

Abstract

2048. Spence, H., Llewellyn, W. B., and Spence & Sons, P. Feb 9. Aluminium sulphate.-The aluminium sulphate liquors obtained from unground calcined coal-measure or like shales are treated for neutralization or rendering; basic with or without concurrent purification from iron by digesting in the absence of the shale-residues with soluble sources of alumina such as bauxite, readily decomposed silicates, aluminates, and basic sulphate compounds, the object being to reduce the quantity of precipitate and facilitate the purification. Excess of potassium sulphate, which is usually present, may be removed as alum in the known manner before or after the treatment. High temperatures, for example 85‹ C. to the boiling-point, and high specific gravities, for example 1À35 to 1À45, are suitable for rapidly effecting the solution of alumina; high specific gravities and lower temperatures, for example 60-80‹ C., are suitable for preventing the precipitation o f basic insoluble compounds as neutralization is approached; lower specific gravities, for example 1À25 to 1À3, and lower temperatures, for example 50-60‹ C-., are suitable for economic purification in substantially neutral or basic solutions; and high temperatures, for example 80‹ C. to the boiling- point, and specific gravities of 1-3 to 1À35 are suitable for. rapid purification and solution of alumina; hut the conditions are varied in accordance with the object or combination of objects in view. Specifications 3805/12 and 22,590/12 are referred to.