A solid flocculating agent, a method for its manufacture and its use.

摘要

The invention relates to a solid flocculating agent comprising at least two components, of which one is aluminium sulphate comprising approximately Al2(SO4)3. (12-18)H2O and the other is an inorganic alkaline compound. The aluminium sulphate and the alkaline compound have such proportions that the ratio between the sum of moles of OH and OH equivalents present in the alkaline compound and the number of moles of aluminium present in the aluminium sulphate is the highest possible but not substantially exceeding a value determined by a specified graph, whereby the flocculating agent when dissolved in water in a concentration range of 0 02 2 0 moles Al 1 gives a clear solution with a high content of multi-nuclei aluminium-hydroxide complexes The invention also relates to a method of producing such an agent, in which an aluminium-sulphate raw material and inorganic alkaline compound(s) are combined in the presence of water in an amount so that a ratio, dust-free composition is provided. The components may be combined in different ways, but it is preferred to mechanically compact an intimate mixture of the components in a finely-divided form and then disintegrate the compacted mass into particulate matter. Another preferred method comtemplates the use of a rotary furnace for producing a granular agent from aluminium sulphate granules and a finely divided alkaline compound in the presence of a minor quantity of water so that the sulphate and the alkali react with each other to form granules.