SU611881A1 - Method of preparing phosphoric acid - Google Patents

Description

The invention relates to methods for producing phosphoric acid, which is used in the chemical industry in the production of mineral fertilizers.

A method of producing phosphoric acid is known by decomposing a phosphate material with a particle size of 15O µm with 14% sulfuric acid at a temperature of 95-1OO C, followed by crystallization and separation of calcium sulfate. The disadvantage of this method is its duration - 1020 hours l.

There is also known a method for producing phosphoric acid by decomposing phosphate raw material with a particle size of 4O-15O µm 4-5 fold excess with respect to the stoichiometry of phosphoric acid at 9O-120 ° C to form monocalcium phosphate pulp, then mixed with sulfuric acid to regenerate phosphoric acid and crystallize the hemihydrate Calcium sulfate At a temperature of 95-100 ° C, the latter is separated from the liquid phase - production phosphoric acid on the bulk filter. The disadvantage of this method is the dilution stage of decomposition (1.5-3 hours) and the low degree of decomposition of phosphate raw material is not more than 98%. 2. The purpose of the invention is to intensify the process and increase the degree of decomposition of phosphate, i.e. increase in product yield.

To do this, the decomposition of phosphate raw materials is carried out while simultaneously grinding with a stirring rate of 10,000-20000 rpm to a grinding fineness of 0.2-5.0 microns at a temperature of 25-60 C.

The feasibility of the selected technological parameters is due to the following: the mixing speed interval is necessary for obtaining the mechanochemical effect, the lower limit is set by experimental - and the upper limit is limited by technical capabilities and modern equipment. The temperature range of 25–60 ° C corresponds to the normal operating conditions of Nienbnitsa when it cools her water jacket, and the increase in temperature RfjHjio of the specified limit is EL non-highly cost-effective.

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lUI. Well .-, how about. increases. equipment corrosion rate. As for grinding, in the specified range, 0.2-5.0 µm, not disaggregation is observed, but the destruction of the crystal lattice due to mechanochemical processes. The proposed method makes it possible to shorten the process time to 15-40 minutes and increase the degree of decomposition of phosphate raw materials to 99-99.7%. Example 1 100 kg of an ap-titanium concentrate and 330 kg of circulating phosphoric acid (48%) are mixed. The resulting pulp is fed into the mill continuously operating in closed-loop mode for ultra fine grinding of suspensions, the rotor speed is 10,000 rpm. The process is carried out at a temperature of 25-35 ° C for 10 minutes, after which the resulting mass is treated with 96.5 kg of sulfuric acid (92.5% LECOM) for 30 min at a temperature of 95-1OO s. The resulting slurry is filtered on a vacuum filter, and the precipitate is washed. The result is the production of phosphorus acid concentration of 52 ,. The degree of decomposition of apatite concentrate is 99.7%. EXAMPLE 2 filtered off, and the precipitate washed. The result is a production phosphoric acid concentration of 53% and large

eil881 dense supipathaccal aggregates (2OOm "m) The degree of washing of calcium sulfate from phosphoric acid is 99.2%, and the degree of decomposition is 99.7%. EXAMPLE 3t 100 kg of the apatite center are mixed with 220 kg of circulating phosphoric acid with a concentration of 40% and with 110 kg (92.5%). The resulting pulp is processed in a mill with a speed of 20 ° C / min at a temperature of 30-40 ° C for 20 minutes. The resulting mass is filtered, and the precipitate is washed. The result is a production phosphoric acid concentration of 50% and calcium sulphate crystals (200 microns). The degree of phosphate decomposition was 99.0%, the degree of washing was 98.9%. The invention of the method for producing phosphoric acid, including the decomposition of phosphate raw materials of circulating phosphoric and sulfuric acids, crystallization and separation of calcium sulfate, characterized in that, in order to intensify the process and increase the yield of the product, the decomposition of phosphate raw materials. rpm to fineness of grinding of 0.2-5.0 microns at a temperature of 25-60 C. Sources of information for emaciation taken into account during the examination: l.CKeu.E: ng: 7O, 14.76, 1963. 2. New research on the technology of mineral fertilizers. Under. Ed.M.E. Pozina, B.A. Kostyleva, L., Khimi, 1970j p. 14-23.