SU990653A1 - Process for producing magnesium hydrophosphate trihydrate - Google Patents

Description

The invention relates to the production of phosphorus compounds, in particular, the production of magnesium phosphate trihydrate, which is used as catalysts, adsorbents, binders and phosphors, and can also be used as a complex fertilizer.

A known method of producing magnesium phosphates by treating dunite or serpentinite with phosphoric acid tl

The magnesium phosphate obtained from the ECM is contaminated with a number of compounds that are present in the feedstock.

The closest to the technical essence and the achieved effect of the invention is a method for producing magnesium trihydrogen phosphate by reacting equivalent amounts of a magnesium salt solution and a phosphate-containing compound, followed by separating, washing and drying the precipitated magnesium hydrophosphate 2 3.

However, when implementing a known method, the resulting three-way. Magnesium phosphate is significantly contaminated with impurities. For example, it contains poorly soluble sodium, the amount of which is 1%.

and more. This is due to the blinking along with the desired product and the by-product of the compound of the composition Mq N and P.04 N P 0

The purpose of the invention is to reduce the content of impurities in the product.

This goal is achieved by the fact that in the method of producing magnesium trivalent hydrogen phosphate by the interaction of equivalent amounts

10 solutions of the magnesium salt and phosphate-containing compound, separating the precipitated precipitate, washing and drying it, use a mixture of hydro5 and sodium dihydrogen phosphate as the phosphate-containing compound.

Moreover, a mixture of sodium hydroxide and dihydrogen phosphate is taken in the ratio (4.5-40):

The use of a phosphate mixture mixture in the ratio (4.5–40) as a phosphate-containing compound allows the precipitation process to be carried out in a more acidic medium, where the pH of the mother liquor is 5—8. Under these conditions, finely dispersed impurities in the form of (he; g and Md Na POij ... Due to this, the content of impurities in the target product is reduced, and also improves 30 with its filtration properties. An increase in the ratio of sodium hydrophosphate to dihydrogen phosphate in the initial phosphate-containing solution more than 40: 1 ,, 1 one Its pH is lower, which does not lead to a noticeable decrease in the content of impurities in the target product and to improve its filtration properties, and a decrease in this ratio below 4.5: 1 leads to a significant acidification of the mother liquor, the pH of which becomes less than 5.2. This significantly increases the solubility of the target product in the mother liquor, which reduces the extraction of ma and phosphorus from the feedstock. To 1000 g of a 25% magnesium chloride solution, with constant stirring, 750.0 phosphate-containing solutions with a content, wt.%: Na2HP04 48.27; NaHgPO D, 22; i.e. with the ratio of HaNzRO equal to 4p. The reaction mass temperature is, and the pH of the mother liquor is 6.3. The resulting suspension is filtered on a laboratory funnel. The filtration rate is 41, -min, the rate of staining is 1.45 m / h, and the content of hydroscopic moisture in the filtered sediment is 15%. The chemical composition of the precipitate after washing with water and drying during the next wn, wt.% MdO 22.9; R20b 40.68; Na 0.07; - the rest. Exit 456.g. -. Example2. To 1000 g of a 25% magnesium chloride solution, with constant stirring, 740 g of the solution with the content, wt.%, Are fed: NaaHPO4 39.98; NDROC 8.81, i.e. the ratio of Na HP04iNaH2PO4, equal to 4.5. The temperature of the reaction mass is, and when the pH of the mother liquor is 5.3. The resulting suspension is filtered. The filtration rate is 42, the settling rate is 1.5 m / h and the moisture content of the filtered sludge is 13%. The chemical composition of the precipitate after washing it with water and drying at the next, wt.%; MDO 22.80; Ruhr 40.61%; Na 0.04; H2O - the rest. Yield 454 g. The main technical and economic indicators of the known and proposed methods for the preparation of magnesium trihydrogen phosphate are given in the table.

Consumption of sodium phosphate (100%) per 1 ton of the target product, t

Sediment settling rate, m / h

. Filter sediment rate,

The moisture content of the filtered precipitate,%

The chemical composition of the target product, wt.%

Using the proposed method, in comparison with the known, an improvement in the chemical composition of the target product due to a decrease in the content of sodium salts hardly soluble in water from 1 to 0.07%, as well as an improvement in filtration properties due to an increase in settling rate, 81-0.79. 15

42 13-15

MDO 22.80, 60 Na 0.07

HjO Rest

nor filtering the resulting precipitate. At the same time, the content of hygroscopic good in the precipitate of magnesium phosphate is 4 times less.

Claims (2)

The economic effect from the implementation of the invention will be 0.59 rubles per tonne of the target product. 5 99 Claim 1. Invention of preparing magnesium phosphate trihydrate by interfering with equivalent amounts. solutions of the mognium salt and the phosphate-containing compound, separating the precipitated precipitate, washing and drying it, in order to reduce the content of impurities in the product, a mixture of sodium and dihydrogen phosphate is used as the phosphate-containing compound. 36 2. The method according to p. 1 about tl. And h. With the fact that the mixture of sodium hydro- and dihydrophosphate is taken in the ratio (4.5-40J: t. Sources of information taken into account during the examination 1 - Pozin ME, Technologists of Mineral Salts, L., Khimi, 1974, - 305. 2. Rassonska N.S., Novikova O.S. Dehydration of crystalline two-substituted magnesium phosphate. Inorganic Hish, 19K5, Vol. 10, no. 6, s. 14gE.