FIELD: chemistry.
SUBSTANCE: invention can be used in the chemical industry. A method of modifying the surface of a mineral material, which is in the form of water sludge or suspension, having pH from 5 to 10, includes addition of, at least, one agent to the said mineral material. The said agent is added in an amount, corresponding to 0.04-1 mg counted per dry weight of the agent per m2 of the total surface of the mineral material. Suspension of the mineral material, which has pH value constituting less than 10 and higher than 7, if a value of an isoelectric point of the said mineral material exceeds 7, and exceeds the value of the isoelecric point of the said material, if the value of the said isoelectric point constitutes 7 or lower. The said agent is in the form of a water solution or a stable water colloid, which has pH lower than 6, and is formed as a result of mixing in a water medium of, at least, one compound, containing phosphonic acid with one or more metal cations or one or more metal-containing cationic compounds. The said metal is selected from the group, consisting of aluminium, zirconium, zinc, cobalt, chrome, iron, copper, tin, titanium and their mixtures. The compound, which contains phosphonic acid and the said cations of metals or the cationic metal-containing compounds, is added in such amount that a molar ratio of phosphonate hydroxyl groups to the metal cation or the metal-containing cationic compound constitutes from 10:1 to 2:1.
EFFECT: invention makes it possible to form filtration or centrifuged sediment of a small volume with high content of solid substances after suspension dehydration.
26 cl, 5 tbl, 2 ex
