SU1664739A1 - Method of producing metal iodides and iodates - Google Patents

Abstract

The invention relates to chemical technology, in particular to methods for producing iodides and metal iodates. In the reaction mixture containing a metal hydroxide, water, the reaction products, iodine is served as a melt with a temperature of 115-160 ° C, with a mass flow rate per 1 m ^{3 of the} reaction mixture within 200-1,500 kg / h at the intensity of the mixing of reagents, characterized by a modified Reynolds criterion between 60 and 4000. The reaction mixture is cooled, and the metal iodate crystals are separated from the mother liquor. The mother liquor is treated with a reducing agent, purified from impurities, cooled, the metal iodide is crystallized. The invention allows to increase the yield on iodine at the synthesis stage from 99.0% to 99.6 - 99.8%, to increase the productivity of the process by increasing the rate of introduction of iodine into the reaction mixture from 125 - 150 kg / h per 1 m ³ the reaction mixture to 200 - 1500 kg / h.

Description

The invention relates to chemical technology, in particular to methods for producing iodides and alkali and alkaline earth metal iodates, which are used as chemical reagents, in the pharmacopoeia, in the production of photographic materials.

The purpose of the invention is to increase the yield of iodine and increase process productivity.

Example 1. Getting potassium iodide. The initial iodine is contaminated with organic and inorganic impurities (12 86.0%, organic impurities 0.20%, ash 0.17%. Nonvolatile 0.37%, water up to 100%). For the purification of iodine, it is melted under a layer of sulfuric acid at 150 ° C. The melt of iodine has the composition: E2 99.5%, organic impurities 0.033%, nonvolatile 0.037%, ash 0.004%. The yield of iodine in the melt is 98.0%.

Potassium hydroxide is used in qualifications of h.h as a solution with a mass fraction of 18.4% KOH. The synthesis process is carried out at a melt flow rate of 800 kg / h, a melt temperature of 150 ° C, the value of the Reynolds criterion (Yavc) 600.

The resulting synthesis synthesis reaction mass contains 31.9% K3, K30s8.2% .l20.4%.

The yield of iodine at the synthesis stage is 99.8%.

The reaction mass at 60-70 ° C is treated with formic acid, 86.0% HCOOH, taken in the amount of 96% of stoichiometry with respect to iodate and iodine. In the resulting solution, impurities of iodate and iodine completely restore the boiling water. ON O J VJ

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With metallic iron, the impurities — an ulfat ion — are purified by treating the solution with barium hydroxide at a stoichiometric ratio of reagents, at a temperature of 100 ° C, and after exposure for 5 hours after treatment for 1.5 hours. Impurities of heavy metals from the solution are precipitated with a hydroxide solution potassium at 95 ° C until a pH of 10.8 is reached. The solution of potassium iodide is filtered from the sludge, evaporated to a concentration of 80% 10 KS, cooled to 25 ° C, potassium iodide is crystallized out and centrifuged from the mother liquor and dried layer at 140 ° C. Get pr ucts corresponding qualification tion 15 pa, the yield of iodine (considering oizvlecheni from the mother liquor) was 98.4% based on the iodine in the melt.

The total yield for iodine based on the initial substandard iodine is 96.4%. 20

Example 2. Preparation of iodide and ± potassium iodate. The process is conducted in accordance with example 1.

99.0 kg of potassium hydroxide solution with a mass fraction of 45% KOH 25 and 10 kg of iodine melt with a temperature of 150 ° C are introduced into the reactor at a rate per 1 m3 of reaction volume of 1200 kg / h. The mixing of the reactants is carried out with an intensity characterized by Recz 600. The obtained 30 reaction mixture is cooled to 20 ° C, the mother liquor containing 50% CG, 2.4% C30, 0.2% KOH and potassium iodate crystals are separated on the filter. Raw iodate is washed on the filter with distilled 35 water to a concentration of 0.04% 3, then dissolved in distilled water, purified from mechanical impurities by filtration, recrystallized and rolled, dried. This gives 2.17 kg of potassium iodate, qualification 40%. Promvody from the washing of iodate are combined with a mother liquor containing potassium iodide with impurities. The mother liquor is treated with formic acid, then the iodide and iodine can be restored to metallic iron. - The resulting solution of potassium iodide is further processed in accordance with Example 1. 6.7 kg of a grade of analytical grade are obtained. The yield of iodine in the products (KSUz and KS), taking into account the additional processing of the mother liquors and the recovery of 4.5 kg of KS, is 98.3%.

Example 3. Obtaining barium iodide and barium iodate.

The melt of iodine, obtained according to example 55 1, with a temperature of 150 ° C is metered into a reactor with a capacity of 1.2 dm, into which 0.94 kg of Ba (OH) and x 8HaOh of brand h and 0.492 kg of water are loaded. 0.744 kg of iodine is introduced for 30 minutes, iodine consumption per 1 m3 of reaction

The total volume is 1500 kg / h. Rec 600.

After the introduction of iodine, the reaction mass is kept under stirring for 10 minutes, filtered, washed, and the barium iodate is dried. Receive 234 g of Ba (30z) 2 marks ch.d.a. The filtrate is boiled with metallic iron, treated with 0.002 kg of Ba (OH) 2 x 8HgO to pH 9.0, re-filtered, evaporated, crystallized, dried 780 g of BaEa x 2X20. The product corresponds to the qualification of h. The yield of iodine into products, taking into account the processing of the mother liquor, and the additional recovery of 248 g of Ba 32x2H20 is 98.0%.

Despite a sharp increase in the temperature of iodine introduced into the reaction mixture (the elasticity of iodine vapor increases from 0.068 kPa at 30 ° C to 52.4 kPa at 160 ° C), due to a change in the state of iodine and an increase in its temperature, the rate of interaction of iodine with hydroxide the metal increases so dramatically that it leads to a significant decrease in the concentration of iodine in the reaction mixture and to the almost complete elimination of iodine losses due to evaporation from the reaction mixture.

The table shows the dependence of the output in iodine on the process parameters.

As follows from the table, when carrying out a process with a melt of iodine within the parameters of the proposed method, the yield of iodine at the synthesis stage increases by 0.8 - 0.5% due to elimination of iodine losses during dosing and as a result of evaporation, the speed of the process increases by 1.5 - 10 times in comparison with the prototype due to a change in the state of aggregation and the temperature of iodine dosed for synthesis.

If the iodine consumption is exceeded, the mixing intensity decreases, or the iodine temperature decreases as compared with the proposed parameter values, the iodine partially crystallizes in the feed line or in the reaction mass, which leads to a decrease in the rate of interaction of iodine with hydroxide and to a stability in the hydrodynamic regime reactor.

When the temperature of the melt of iodine is exceeded and the intensity of mixing in relation to the proposed values of the parameters, energy costs increase without obtaining an additional positive effect. Reducing the consumption of molten iodine leads to a decrease in the performance of the reaction apparatus.

The increase in the intensity of the mix- jjanHH from Нвц 4000 to Р rec 5000 does not lead

to increase the yield of iodine, however, this increases the energy costs of the implementation of mixing.

The proposed method allows to increase the yield on iodine during the synthesis from 99.0 to 99.6%, to increase the productivity of the process by increasing the rate of introduction of iodine into the reaction mixture from 125-150 kg / h per 1 m3 of the reaction mixture to 200-1500 kg / h

Claims (4)

Claim 1. A method of producing metal iodides and iodates, including the interaction of iodine with a hydroxide of the corresponding metal in an aqueous medium with stirring, the isolation of metal iodate crystals, the separation of crystals from the iodide metal solution, treatment of solution i the reducing agent, its purification, separation from impurities, evaporating, crystallization and drying of the metal iodide, characterized in that, in order to increase the yield on iodine and increase the productivity of the process, iodine is taken as a melt. 2. A method according to claim 1, characterized in that the mass flow rate of the iodine melt in 0 per 1 m3 of the reaction mass is 200-1500 kg / h. 3. The method according to claim 1, characterized in that the melt of iodine is taken with a temperature of 120-160 ° C. five 4. A method according to claim 1, characterized in that the mixing of the reactants is carried out with an intensity characterized by a Reynolds criterion of 60-4000.