SU1624057A1 - Processes for preparing solution of mixed magnesium chlorate and hypochlorite - Google Patents

Abstract

The invention relates to the chemical and electrolytic production of oxygen-chlorine compounds, to the technology of boron compounds and is used to obtain an oxidizing agent used, in particular, in the purification of boric acid process solutions from boron magnesium raw material from iron (II). The aim of the invention is to simplify the process and eliminate the consumption of reagents. The invention consists in direct electrolytic oxidation of magnesium chloride solution, preferably in the form of bischofite, containing 47–70 g / l magnesium chloride, 30–60 g / l boric acid, 170–220 g / l magnesium sulfate and 0 5–0 8 g / l calcium sulphate, at pH 4.5 - 6 in an electrolyte-free bath with an insoluble anode. A current density of 8–12 A / dm2 and a temperature of 20–50 ° C, with obtaining in terms of active chlorine, the ratio of chlorate and hypochlorite to (2–3) 1 and their content up to 75–80% of the total chlorine

Description

The invention relates to the chemical and electrolytic production of hp-oxygen compounds, to the technology of boron compounds, and can be used to obtain an oxidizing agent, which is used, in particular, in the purification of bivalent iron from boric acid production solutions

The purpose of the invention is to simplify the process and eliminate the consumption of reagent.

PRI me R 1. A solution is prepared by electrolysis of a mixture of chlorate and magnesium hypochlorite from a solution of magnesium chloride in a boric acid mother of boric acid from magnesite neutralized from magnesium magnesium at pH 6

110 g of crystalline bischofite with a content of 45% MgCl2, which corresponds to 100 g of MgCl2-6H20, 0 93 l of boric acid stock solution containing 6.40% MgO in the form of sulphates, 1.70 are taken to prepare 1 l of the initial solution. % B203 and 0.46 g / l Fe2 +, and 3.2 g of magnesite with a content of 87.5% MgO. The mixture prepared by dissolving is poured into the electrolyzer without a diaphragm with an anode of graphite and a cathode of titanium, and its current is electrolytically. 10 A / dm2, current strength 10 A and electrolyte temperature 35 ° С for 3 h 20 min

As a result of the electrolysis, 1 l of a solution of a mixture of chlorate and magnesium hypochlorite containing 8.3 g / l of SW is obtained. 7.7 g / l OSSY 0.43 g / l ReZ as a suspension of its hydroxide In the target product (solution) in terms of active chlorine, the ratio of chlorate and hypochlorite is Rapo 2 1, the degree of oxidation of chlorine is 79 1% Total

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Yu

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| SL xj

The current output of chlorate and magnesium hypochlorite, as well as iron (III), is 72.8%.

Example. In contrast to example 1, in the preparation of 1 l of the initial solution, take 165 g of crystalline bischofite, which corresponds to 150 g of MDS bNsOz 0.89 l of boric acid stock solution and 3 g of magnetite and electrolytic oxidation of the mixture is carried out for 3 hours 50 min

As a result of electrolysis, 1 l of a solution of a mixture of chlorate and magnesium hypochlorite containing 11.5 g / l CUc, 7.2 g / l OCI and 0.41 g / l Fe 3+ in the form of its hydroxide is obtained. In the product of chlorate and hypochlorite is 3: 1. horse chlorine oxidation - 75%. The total current output of chlorate, hypochlorite and iron (II 1) is 77.6%.

PRI me R 3. In contrast to example 1,; A gr of a mixture of chlorate and hypochlorite is half-bent from a solution with a higher concentration of magnesium chloride in the boric acid mother liquor neutralized with flash ore at pH 4.5. For the preparation of 1 l of the initial solution (suspension), take 144 g of crystalline bischofite, which corresponds to 125 g of MdCl 6H20, 0.89 l of boron stock solution; gy and 43 g of borate ore, containing - (g-shry 5 , 76% MgO, 18% and 0.6% FeO, and) Lcrolitic oxidation of the mixture is carried out in, 4 h

As a result of the electrolysis of pof, -: 1 l of a solution of chlorate suspension and magnesium hypochlorite, containing 10.3 g / l of SES, 5.83 g / l of OS and 0.64 g / l in the form of rj CRG, and its hydroxide. In the product, the ratio of pore; a and hypochlorite is: - the degree of chlorine oxidation is 78.5%. The total current output of chlorate, hypochlorite and iron (III) is 65.7%.

PRI me R 4. In contrast to example 2, electrolytic oxidation is carried out at 20 ° C for 2 hours and 15 minutes.

As a result of electrolysis, 1 l of a solution of a mixture of chlorate and hygiene: magnum magnum containing 4.2 g / l CUy and 10.6 g / l of OCG is obtained. In the product, the ratio of chlorate and hypochlorite is 0.7: 1. the degree of chlorine oxidation is 48.2%. The total current output of chlorate, hypochlorite and iron (III) is 85.7%.

EXAMPLE 5 An electrolysis solution is obtained for a mixture of chlorate and magnesium hypochlorite from a solution of magnesium chloride in a magnetically neutralized mother solution of boric acid with an extremely high content of V203.

On the preparation of 1 l of the original solution, take 110 g of crystalline bischofite

with a content of 45% MgCte. which corresponds to 100 g of MgCh 6H20, 0.93 l of boric acid stock solution containing 2.43% B203 in the form of boric acid, 0.60% H2SCM

5.30% MgO, 0.45 g / l Fe2 and 0.26 g / l Fe3 +, and also 3.1 g of caustic magnesite with 89% MgO content and in the form of sulfates 5.30% MgO.

Mix prepared by dissolving

0 having a pH of 5.5, is oxidized in a diaphragm-free electrolyzer, with a graphite anode and a titanium cathode, at a current density of 13 A / dm2, current of 10 A, and a temperature of 35 ° C for 3 hours and 15 minutes.

5In the result of electrolysis receive i l

the target solution of a mixture of chlorate and magnesium hypochlorite, containing 9.2 g / l COOOz, 6.8 g / l OSG and 0.66 g / l Fe3 in the form of a suspension of its hydroxide. The ratio of chlorate and hypochlorite in terms of active chlorine in the target solution is 2.5: 1. The total current output of magnesium chlorate, magnesium hypochlorite and iron (III) is 76.5%.

5 Example 6. Unlike example 5,

the electrolysis is carried out at a gok density of 8 A / dm, a current of 8 A for 4 h.

As a result of electrolysis, 1 l of the target mixture of chlorate and

0 Magnesium hypochlorite with a content of 8.2 L g / n SUS, 6.7 g / l OSG and 0.66 g / l Fe. The ratio of chlorate and hypochlorite in terms of g. Chlorine in it is 2.55: 1, the total current output of chlorate, hypochlorite; and iron

5 (HI) 76.2%.

Example. Unlike example 5,

electrolysis is carried out at a current density of 12

A / dm, current strength 12 A for 2 h 50 min.

In the electrolysis receive so

At the same time, 1 l of the target solution of a mixture of chlorate LI of magnesium hypochlorite with a content of 9.0 p CET, 7.25 g / l of CGG and 0.66 g / l of Fe3 +.

The ratio of chlorate and hypochlorite in terms of active chlorine in it is 2.3: 1.

5 The total current output of chlorate, hypochlorite and iron (111) is 74.3%.

Example Unlike Example 5, electrolysis is carried out at 50 ° C for 3 hours and 30 minutes.

As a result of electrolysis, 1 l of the target solution of a mixture of chlorate and magnesium hypochlorite is also obtained with a content of 9.6 g / l CUz, G 3 g / l OXY 0.66 g / l Fe34.

The ratio of chlorate and hypochlorite about

5 recalculated active chlorine in it 2.8: 1. The total current output of chlorate, hypochlorite and iron (III) is 72.4%.

PRI me R 9. Get a solution of a mixture of chlorate and gypsum chlorophosphate and the proposed method.

To prepare the initial solution for electrosynthesis of the target product, take 0.89 l of the boric acid production solution from the bormonium feedstock containing 2.4% V203 in the form of boric acid, 0.6% H2SO-1 free in the form of boric acid and 5.3% MgO in the form of sulfates and 0.054% FeO. 3.2 g of caustic magnesite containing 89.0% MgO to neutralize the free acid are added to the indicated volume of the mother liquor, and 165 g of crystalline bischofite containing 45% MgCl2 is dissolved in this neutralized solution. Get 1 l of the original electrolyte composition, g / l: MgCl2 70; The HEO 41.5; MgS04 164; FeS04 1.3 and pH 5.3.

The prepared solution is poured into an electrolyzer with an anode made of graphite and titanium made of titanium with a working surface of 1 dm2, and treated at a current density of 8 A / dm2 (current strength 8 A), temperature 30 ° С and voltage of 2.8 - 3 , 0 V for 4 h 50 min.

In the process of electrosynthesis at the anode, chlorine anions are discharged to form chlorate and hypochlorite in solution and partially release gaseous chlorine from the electrolyzer, oxidize iron (II) cations to iron (hi), and also partially decompose water molecules to release gaseous oxygen. At the cathode there is a discharge of hydrogen cations with the release of gaseous hydrogen. In this case, the precipitate of magnesium hydroxide on the kztode and in the electrolyte bulk does not form.

As a result of the electrolytic treatment, 1 l of a solution of a mixture of chlorate and magnesium hypochlorite containing, g / l: Mg (S13) 2 13.2: MgfCIOfc 9.1; MdS12 45- Mdz (VOZ) 2 7,8; NZOZ 36.4; MgSO /, 16; FeOHSO i 1,4; with a total current output of chlorate, hypochlorite and iron (III) 78.0%. In the product, in terms of active chlorine, the ratio of chlorate and hypochlorite is 2.35: 1 differently and the degree of conversion (oxidation) of chlorine from chlorine is 75.8%. The yield of chlorine released is 17%.

Example 10. Get a solution of chlorate magnpch in a known manner.

In contrast to Example 9, for preparing a stock solution for electrosynthesis of the target product, 0.90 L of water is taken and 165 g of crystalline bischofite with 45% MgCfe content is dissolved in it. Paul-v-iaiOT 1 l of the original electrolyte containing U 70 g / l MgCl2, pH 5.3. The electrolysis of PG,.) Was carried out in the same cell and under those / ke conditions and duration as in Example 9, carried out only an additionally continuous intensive mechanical stirring of the solution.

In the process of electrolysis at the anode, the discharge of chlorine anions occurs with the release of gaseous chlorine from the electrolyzer and the partial formation of chlorate and hypochlorite of magnesium in the solution, as well as the partial decomposition of water with the release of gaseous oxygen. The cathode mainly decomposes water molecules and partially discharges hydrogen cations with the release of gaseous hydrogen and precipitation of magnesium hydroxide on the working surface. The voltage on the electrolysis 5 is 6-7 V. (Without stirring the electrolyte, electrolysis stops after 1.5 hours due to an increase in voltage to 10 - 12 V and a low current that increases with time).

As a result of electrolytic treatment, 1 liter of the final solution containing 6.4 g / l of MD (CU3) 2 is obtained; 1.8 g / l Md (CU) 2 (in terms of active chlorine, the ratio of chlorate and hypochlorite is 7.2; 1 with

5 degrees of chlorine oxidation (31.3%) and 22.4 g / l MgCl2, with a total chlorate and hypochlorite current output of 32.0%. The current emitting chlorine is 63.0%. Amount of precipitate MD (OH) 2

0 26.3 g (0.68 g / A.h.).

In order to obtain a solution and magnesium hypochlorite, an electrolyte is proposed, which is a solution of a mixture of magnesium chloride and neutralized with a magnesium mesite or borate ore sulphate of the mother liquor produced in boric acid

Electrolig contains, g / l: MgCl2 6H20 JUS - 150: MgCl2 47 - 70; BWT 30 - 60;

0 MgSCM 170 20; SoZoz 0.5 - 0.8, and has a pH of 4.5-6.

Magnesium chloride concentrations in the range of 100–150 g / l MgCl2-6H20 provide the proposed conditions for electrolysis

5 production of rastsor chlorate mixtures of magnesium hypochlorite with their ratio in terms of active chlorine (2–3.3): 1 and a chlorine oxidation state of 75–80% with a go yield of 65–85%.

0 At concentrations below 100 g / l MgCl2

“6Н20, especially below 80 g / l, along with the oxidation of chlorine ions, there is a noticeable release of oxygen. The current efficiency of active chlorine drops to 50–60% and the loss of the graphite anode sharply increases (although the degree of oxidation of chlorine in this case can be reached -80% and its Bol) Concentrate - h above 150 g / l MgCl2 6H20, despite the achievable high current output of chlorate and hypochlorite (857 and more)

less appropriate because the degree of chlorine oxidation and the ratio of chlorate and hypochlorite in the resulting product are reduced, especially at low temperatures

(respectively up to about 50% and 0 7: 1 with

2 OC).

Concentrations of 30 - 60 g / l HPO3; 170 - 220 g / l MgSCM and 0.5 - 0.8 g / l CaSCM are determined by applying to 1 liter of the prepared starting mixture for electrolysis, 0.85 - 0.93 l of boric acid liquor containing, based on oxides, 5.3 - 6.4% of MDO, 1.7-2.4% of V.OzidoO, 6% of H2S04 and having a density of 1.1 g / cm. With a different volume of the taken mother liquor, the concentration of MgCl2-6H20 will change to one side or the other in the electrolyte. Reducing the content of boric acid and magnesium and calcium salts in the electrolyte by diluting the mother liquor or the prepared mixture with water cannot be used according to the main production conditions of boric acid, in which the resulting solution of a mixture of chlorate and magnesium hypochlorite is subsequently used. With regard to eliminating the formation of a precipitate Md (at the cathode, it is enough for it to be two times lower in the content of boric acid in the electrolyte.

A pH of 4.5-6 is optimal for electrolytic treatment. Lower pH values are unacceptable because they exclude the presence of OH anions necessary for the formation of hypochlorite and chlorate in the electrolyte. pHs above 6 (up to 7) are applicable, but less appropriate, since in this case additional acidification of the solution will be required during the electrolysis process.

Thus, the application of this method allows to simplify the technology and instrumentation of the process of obtaining a solution of a mixture of chlorate and magnesium hypochlorite by eliminating their separate preparation by a complex multistep technology and subsequent mixing.

(dissolving) with the elimination of the steps of evaporation of sodium chlorate solution, crystallization of solid sodium chlorate, high-temperature interaction of sodium chlorate with melt magnesium chloride (bischofite) to obtain solid magnesium chlorate, obtaining a solution of caustic alkali and gaseous chlorine from a solution of sodium chloride in a diaphragm sample. caustic alkali; and transfer of sodium hypochlorite solution into magnesium hypochlorite solution with magnesium chloride. In addition, sodium chloride consumption is eliminated and magnesium chloride consumption is reduced.

to receive chlorate and magnesium hypochlorite; increases the stability of the active chlorine obtained (in the form of chlorate and magnesium hypochlorite) and the degree of chlorine oxidation (i.e., the relative content of active chlorine) while excluding the presence of sodium dichromate impurity in the target product (solution).

Claims (1)

DETAILED DESCRIPTION OF THE INVENTION A method for producing a solution of a mixture of chlorate and magnesium hypochlorite, comprising the electrolysis of metal chloride solutions using an insoluble anode, characterized in that. that, in order to simplify the process and eliminate the consumption of reagents, a solution containing 47–70 g / l of magnesium chloride, 30–60 g / l of boric acid, 170–220 g / l of magnesium sulfate, 0.5 - 0 is subjected to electrolysis. , 8 g / l calcium sulphate and having a pH of 4.5 6 .0, and electrolysis is carried out at a current density of 8 - 12 A / dm2 and 20 - 50 ° C.