RU2210532C1 - Potassium iodide production process - Google Patents

Abstract

FIELD: industrial inorganic synthesis. SUBSTANCE: process involves chemical interaction of aqueous iodine suspension with potassium hydroperoxide until iodide concentration 400-600 g/l in reaction milieu is obtained. Reaction milieu is the subjected to two-step concentration. In the first step, mixture is evaporated to 900-950 g/l iodide ion concentration, after which dissolved impurities are isolated from reaction milieu. In the second step, reaction milieu is evaporated to 2000-2500 g/l iodide ion concentration enabling crystallization of desired product. EFFECT: increased yield of potassium iodide in shortened production cycle and reduced power and labor consumption. 2 cl

Description

 The invention relates to the technology of iodine compounds, and more specifically relates to a method for producing potassium iodide.

 The invention will find application in the pharmaceutical industry in the manufacture of medicines of a fairly wide spectrum of action. In connection with the indicated use of potassium iodide, quite strict requirements are imposed on this product for the content of impurities, namely, the resulting potassium iodide should not contain sulfates - more than 0.01 wt.%, Heavy metals - not more than 0.001 wt.%, Iron - not more than 0.001 wt.%, arsenic - not more than 0.0001 wt.%, the mass fraction of potassium iodide should be at least 99.5%.

A known method of producing potassium iodide, including synthesizing the target product in a reaction mass by reacting iodine with potassium hydroperoxide, for which an alkaline hydrogen peroxide solution having a temperature of 8-10 ^o C. is added to the solution of iodine in potassium iodide with stirring and cooling. maintain at a level of 20 ^o C. In the process of synthesizing the target product in the reaction mass repeatedly enter new portions of a solution of iodine in potassium iodide and an alkaline solution of hydrogen peroxide until tion in the reaction mass of the content of the target product in the amount of 550 kg / cubic meter. According to the known method, in the synthesis process, about 60% of the formed target product is used to form the initial solution of iodine in potassium iodide.

The reaction mass with the formed potassium iodide is further purified from impurities - magnesium salts, iron, sulfates, for which, in particular, iron chips, barium hydroxide, purified from impurities, are used, heating the reaction mass to a boil, which ensures coagulation of iron hydroxide. The reaction mass treated in this way is filtered and concentrated, for which it is subjected to partial evaporation under vacuum of 0.06-0.08 mPa / cu. cm at a temperature of 100-120 ^o C, then again filtered and subjected to complete evaporation at a temperature of 80-90 ^o C to saturate the reaction mass according to the content of potassium iodide, the reaction mass is cooled until crystals of the target product precipitate. The formed crystals of potassium iodide are separated from the mother liquor and dried to a moisture content of 20% in a suspended layer at 160-170 ^o С (V.I. Ksezenko, D.S. Stasinevich "Chemistry and technology of bromine, iodine and their compounds", Moscow, " Chemistry, 1995, pp. 396-397).

 To increase the content of the main substance in the obtained product, a well-known technique is used, namely, that the initially dried salt, potassium iodide, is dissolved in distilled water, then the resulting solution is evaporated to saturation, cooled, and then crystals of the target product are separated from the mother liquor and subjected to drying to a basic substance content of at least 98%.

 As can be seen from the foregoing, the known technology for producing potassium iodide is multistage and is based on the use of a starting reagent saturated in the target product, as well as on the implementation of multiple recrystallization of the reaction mass containing the target product. At the same time, energy and labor costs significantly increase the cost of the resulting substance.

 The basis of the claimed invention is the task of creating such a method for producing potassium iodide, which would provide a high yield of the target product for a shorter production cycle while reducing energy and labor costs for obtaining the target product.

 This problem is solved using the method of producing potassium iodide, including the chemical interaction of an iodine-containing reagent with potassium hydroperoxide with the formation of the target product in the reaction mass, separation of dissolved impurities from the reaction mass, evaporation of the reaction mass, which ensures crystallization of the target product in the reaction mass, crystallization of crystallized from the reaction mass potassium iodide, in which, according to the invention, as an iodine-containing reagent, an aqueous suspension of iodine is used, chemically Interaction of an aqueous suspension of iodine with potassium hydroperoxide is carried out until the concentration of iodine ions in the reaction mass is 400-600 g / l, and the reaction mass is evaporated in two stages, in the first of which the reaction mass formed under the indicated chemical interaction, and lead it until the iodine ion concentration in the reaction mass reaches 900-950 g / l, and in the second stage, the reaction mass is evaporated until the ion concentration in it is reached iodine equal 2000-2500 g / l, and the selection of dissolved impurities is carried out after the first stage of evaporation.

 Thanks to the invention, it is possible to increase the yield of the target product in a shorter production cycle while reducing energy and labor costs for obtaining the target product.

 According to the invention, it is advisable to isolate dissolved sulfate-containing impurities when using barium hydroxide and filtering the reaction mass.

 Further objectives and advantages of the claimed invention will become apparent from the following detailed description of the method for producing potassium iodide.

 The inventive method for producing potassium iodide (KJ) is based on the peroxide method and allows you to form a reaction mass containing the target product, and not containing iodates.

Суммарная реакция образования иодида калия:
J₂+2КОН+Н₂O₂=2KJ+2Н₂O+O₂

Одновременно при взаимодействии йода со щелочью образуются промежуточные соединения - гипойодиты, из которых образуются йодаты:
2КОН+J₂=KJO+KJ+Н₂О
3KJO=КJO₃+2KJ
В присутствии перекиси водорода гипойодит калия восстанавливается до йодида калия по реакции:
KJO+Н₂О₂=KJ+Н₂О+O₂

Перекись водорода в щелочной среде малоустойчива и медленно разлагается по уравнению
2Н₂O₂=2Н₂O+O₂

+23,4 Кал
Согласно изобретению, химическое взаимодействие водной суспензии йода с гидроперекисью калия (КООН), обеспечивающее синтез целевого йодида калия, осуществляют до достижения в реакционной массе концентрации по ионам йода, равной 400-600 г/л.The inventive method for producing potassium iodide involves the chemical interaction of an aqueous suspension of iodine with potassium hydroperoxide (UNC), while the formation in the reaction mass of the target product is carried out according to the following chemical scheme:
2KOH + H ₂ O ₂ = UNO + KOH + H ₂ O
J ₂ + COOH + KOH = 2KJ + 2H ₂ O + O ₂

The total reaction of the formation of potassium iodide:
J ₂ + 2KOH + H ₂ O ₂ = 2KJ + 2H ₂ O + O ₂

At the same time, with the interaction of iodine with alkali, intermediate compounds are formed - hypoiodites, from which iodates are formed:
2KOH + J ₂ = KJO + KJ + H ₂ O
3KJO = KJO ₃ + 2KJ
In the presence of hydrogen peroxide, potassium hypoiodite is reduced to potassium iodide by the reaction:
KJO + H ₂ O ₂ = KJ + H ₂ O + O ₂

Hydrogen peroxide in an alkaline medium is unstable and slowly decomposes according to the equation
2H ₂ O ₂ = 2H ₂ O + O ₂

+23.4 Cal
According to the invention, the chemical interaction of an aqueous suspension of iodine with potassium hydroperoxide (COOH), which ensures the synthesis of the target potassium iodide, is carried out until the concentration in the reaction mass of iodine ions of 400-600 g / L is reached.

The resulting reaction mass directly in the volume where the synthesis of the target potassium iodide was carried out, is subjected to partial concentration - the first stage of evaporation. The first stage of evaporation takes advantage under a vacuum of 0.06 MPa and a temperature of 105-110 ^o C to achieve in the reaction mass concentration of iodine ions (J ^- ) equal to 900-950 g / L. In this case, concentration of all substances present in the reaction mass is achieved, including salts of magnesium, iron and sulfates, which are impurities, and the target potassium iodide. Since salts of magnesium, iron and sulfates are sparingly soluble substances, their partial precipitation occurs. The target potassium iodide, being a well-soluble compound (solubility from 2000 g / l), is stored in the reaction mass under the indicated conditions in a dissolved state.

 Thus, according to the invention, evaporation in the first stage provides a partial separation of impurities.

As indicated above, evaporation in the first stage is carried out until the concentration in the reaction mass of iodine ions (J ^- ) of 900-950 g / l is achieved, which ensures, against the background of partial precipitation of impurities, the preservation of the target product in dissolved form.

 The condensate formed during evaporation can be used to prepare the initial aqueous suspension of iodine.

Then, essentially, once again, dissolved impurities are isolated from the reaction mass, for which barium hydroxide is introduced into the reaction mass, the reaction mass is heated to a temperature of 50-80 ^° C, the sulfates present are precipitated and sedimentation is carried out. Purified from sulfates, the reaction mass is further purified from alkaline earth and heavy metals by introducing potassium carbonate and heating the reaction mass to a temperature of 50-80 ^o C.

 Next, the purified and cooled reaction mass is subjected to filtration, due to which the impurities crystallized and precipitated are separated.

Purified from impurities, the reaction mass is subjected to evaporation (second stage) by no more than 50% with reaching a concentration of iodine ions of 2000-2500 g / l in it. Mostly evaporation is carried out under vacuum at least 0.4 kg / sq. cm and a temperature of at least 70 ^o C. Under these conditions, the formation of crystals of the target product - potassium iodide.

 The condensate formed during evaporation can be used to prepare the initial aqueous suspension of iodine.

After evaporation, the mass is cooled to 20-25 ^o C, while there is a complete crystallization of potassium iodide. Potassium iodide crystals are separated by filtration from the mother liquor and dried to achieve a mass fraction of potassium iodide in the substance of at least 99.5%.

 The resulting potassium iodide contains sulfates in an amount of not more than 0.01 wt. %, heavy metals - in an amount of not more than 0.001 wt.%, iron - in an amount of not more than 0.001 wt.%, arsenic - in an amount of not more than 0.0001 wt.%.

 The inventive method provides an increase in the yield of the target product for a shorter production cycle while reducing energy and labor costs to obtain the target product, as it provides for the possibility of the entire process at the minimum production area using two or three reaction tanks.

Example
1. Preparation of potassium hydroxide solution
450 l of condensate are introduced into the reactor and 109 kg of 90% potassium hydroxide are added in portions with stirring until the concentration of potassium hydroxide solution reaches 200-250 g / l.

2. Preparation of a solution of potassium hydroperoxide
Hydrogen peroxide, taken with a 30% excess from stoichiometry, is introduced into the reactor with a prepared potassium hydroxide solution with stirring.

3. Preparation of a suspension of iodine
220 kg of fine crystalline iodine are introduced into the reactor containing 250 liters of water or condensate with stirring.

4. Synthesis of potassium iodide
A potassium hydroperoxide solution (650 kg) is introduced into the reactor containing the prepared suspension of iodine (470 kg). After the end of the interaction of the reagents, determined by the color change of the reaction mass from brown-brown to orange-yellow, analytically determine the mass concentration of iodide and the concentration of iodine ions, which is 400-600 g / l.

5. The first stage of evaporation
The contents of the reactor used for the synthesis of potassium iodide are heated to boiling and evaporated under vacuum 0.06 MPa and a temperature of 105-110 ^o C for 16 hours until the concentration of iodine ions in the reaction mass reaches 900-950 g / l. Partially precipitated poorly soluble substances - impurities present in the reaction mass.

 The condensate formed during the evaporation process is collected in a vacuum collector, from where it is sent to the "Preparation of iodine suspension" stage.

One stripped off reaction mass is checked for sulfates. If the result is positive, barium hydroxide is added in portions to the reactor. The reaction mass is stirred with compressed air. To complete the deposition of barium sulfate, heating is carried out to a temperature of 50-80 ^o C. The reaction mass is then defended.

The sulfate-free reaction mass is further purified from alkaline earth and heavy metals by precipitation of hardly soluble carbonate precipitates when potassium carbonate is added in portions. The process is carried out at a temperature of 50-80 ^o With constant stirring. The reaction mass is then defended.

 Purified from these impurities and cooled the reaction mass is subjected to filtration on a filter. As a filter material, two layers of filter paper are used.

The filtered reaction mass is then sent to the evaporator to carry out the second stage of evaporation. Evaporation is carried out in a vacuum evaporator with a discharge of 0.06 MPa and a temperature of 110-118 ^o C.

 The mother liquor of the previous synthesis of the target product is added to the evaporated reaction mass.

 Evaporation of the reaction mass is carried out until it reaches a concentration of iodine ions of 2000-2500 g / l, while observing the appearance of a film of crystals of the target product on the surface of the reaction mass.

 The condensate formed during the evaporation process is collected in a vacuum collector, from where it is sent to the "Preparation of iodine suspension" stage.

 After evaporation, the contents of the evaporator are cooled with constant stirring, resulting in complete crystallization of potassium iodide.

 After separation of the mother liquor from the formed crystals of potassium iodide, the latter is loaded onto a nunch filter in order to more fully separate the mother liquor and primary drying of the target product.

 The mother liquor is collected in a vacuum collector, from where it is sent to the second stage of evaporation.

After primary drying, the target product is placed in a vacuum drying oven. Drying is carried out at a temperature of 70-90 ^o With periodic tedding of the product.

 The dried product (275 kg) contains potassium iodide in an amount of not less than 99.5%, sulfates in an amount of not more than 0.01 wt.%, Heavy metals - in an amount of not more than 0.001 wt.%, Iron - in an amount of not more than 0.001 wt.%, arsenic - in an amount of not more than 0.0001 wt.%.

Claims (2)

 1. A method of producing potassium iodide, including the chemical interaction of an iodine-containing reagent with potassium hydroperoxide with the formation of the target product in the reaction mass, separation of dissolved impurities from the reaction mass, evaporation of the reaction mass, providing crystallization of the target product in the reaction mass, isolation of crystallized potassium iodide from the reaction mass, characterized in that as an iodine-containing reagent an aqueous suspension of iodine is used, the chemical interaction of an aqueous suspension of iodine with hydro potassium peroxide is carried out until the concentration of iodine ions in the reaction mass is 400-600 g / l, and the reaction mass is evaporated in two stages, in the first of which the reaction mass formed during the indicated chemical interaction is subjected to evaporation and is carried out until achieving a concentration in the reaction mass of iodine ions equal to 900-950 g / l, and in the second stage, the evaporation of the reaction mass is carried out until reaching a concentration of iodine ions of 2000-2500 g / l, while the solution is isolated nnyh impurities is carried out after the first stage of evaporation.  2. The method according to p. 1, characterized in that the separation of dissolved impurities is carried out using barium hydroxide by filtering the reaction mass.