SU1054303A1 - Method for preparing solution of iron (iii) chloride - Google Patents

Abstract

1. METHOD FOR PRODUCING SOLUTION OF IRON CHLORIDE

Description

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The invention relates to the technology of inorganic synthesis and can be used in the chemical industry to produce an aqueous solution of ferric chloride (111), widely used as a coagulant.

A known method for producing an aqueous solution of ferric chloride (HI), which consists in the interaction of waste process gases containing chlorine and hydrogen chloride, with an aqueous solution of ferric chloride (11). The process includes two stages: the stage of oxidation and the stage of reduction. Exhaust gases (containing up to 1510 kg / m of chlorine and up to kg / m of hydrogen chloride) are fed to the scrubber of the first stage of the purification system irrigated with a solution of ferric chloride (11). The resulting oxidation process is described by the equation

2 ReСВ2 + СС2 2 FeCe, + 14,8 g | (one

Simultaneously with the chemisorption of chlorine, a physical solution of hydrogen chloride occurs. The resulting solution of ferric chloride (111) has the composition; FeCg 34-35; FeCgg 2-3 and NeB 1-2. From the scrubber of the first stage, the gases are sent to the second stage of purification, where in the same column the chlorine residues are absorbed with a fresh solution of ferric chloride (11). The latter is obtained in the second stage of the process (reduction stage) in a special backwater solvent by recovering part of the commodity solution of iron chloride (111) on steel chips:

kcal

2 FeCe2 + 17.4

x2

mole

2 her + Fe

FeC6 + H (3

A solution of ferric chloride (11) from the scrubber of the second stage of purification is used to irrigate the scrubber of the first stage H.

The described scheme is applicable at a low content of hydrogen chloride in the exhaust gases, when, after absorption, the concentration of hydrochloric acid in the commodity solution of ferric chloride (111) does not exceed the requirements of specifications (no more than 1.5%).

The closest in technical essence and the achieved result to the invention is a method of obtaining a solution of ferric chloride (111) based on abgasny chlorine and hydrogen chloride. The process is carried out in two stages. At the first stage, chlorine and hydrogen chloride are absorbed in an absorber irrigated with an aqueous solution of ferric chloride (111 From the absorber, a solution containing smaglia ferric chloride (11) and (111)

and hydrochloric acid enters the bath-reactor, where iron waste is loaded and water is metered (hydrochloric acid and water are used during the start-up period). In this case, reactions (2) and (3) proceed in the bath, the process proceeds at F0-70s. Maintaining the temperature is achieved by the supply of live steam. The resulting solution of ferric chloride (SI) is circulated by means of a pump between the sanitary column and the bath until the total iron chloride content (11) and (111) is 185210 kg / m and the acidity is reduced to an acceptable level.

Dash solution is fed to the second stage, where the interaction with pure chlorine receive marketable. ferric chloride solution (ill),%: FeCP3 36-42,5; FeCP 0.5; C (cso6, 0.01; acid equivalent 9-12,8, meeting the requirements of consumer 2.

The known method is characterized by a lack of purity of the product, especially when using the waste gases of organochlorine production; the duration of the process due to the low rate of dissolution of the steel chip and the absence of effective mixing; energy consumption associated with the need to supply steam to maintain the temperature during the recovery stage,.

The aim of the invention is to increase the purity of the product, accelerate the process and reduce energy costs.

The goal is achieved according to the method of producing an iron chloride solution (J11), including dissolving iron chips in hydrochloric acid, absorbing the resulting solution of gases containing chlorine and hydrogen chloride, and subsequently treating the solution with chlorine, absorbing gases containing chlorine and hydrogen chloride , lead in the presence of iron shavings.

The absorption of gases containing chlorine and hydrogen chloride, is carried out at 8085C,

The method is carried out as follows.

Gases containing chlorine and hydrogen chloride are fed to the working zone of the absorber, where steel chips and hydrochloric acid are loaded. The composition of the reaction mass, wt.%: FeCfij 3235; Fece 2-5; NA 1.3-3.0; the rest is water. Water is fed to the absorber to dilute the solution. The temperature in the absorber is set in the range of 60-85 0 due to the thermal effect of the reactions and the natural heat release to the environment. The outlet gases from the apparatus, containing hydrogen, inerts, and sometimes impurities of organic and organochlorine substances, are diluted directly in the apparatus to an air-safe hydrogen concentration (2-25% by volume) and sent to a common abgasic collector. (11) first comes from the absorber to the irrigation of two sanitary columns, and then to the treatment with chlorine or ohm or chlorine-containing gas into the column, where, at 75-80s, a solution of ferric chloride (111) of the following composition is obtained, May 1.0; 1.4-3.0. The presence of contaminants in and Chips used (lubrication, cooling mixtures, etc.) or the use of organochlorine production gases (for example, perchlorovinyl resin production) cause the appearance of organic impurities in the solution of ferric chloride (111) at the level of 35 mg / l. is subjected to inert purging at 80-85 ° C to reduce the level of organic matter to the requirements of Specification. . The interaction of the ferric chloride solution (11) with gases containing chlorine and hydrogen chloride is carried out in an apparatus where forced or natural circulation of the reaction mass is ensured. In the latter case, a gas lift type apparatus with an internal or external circulation loop is used. Example 1. I load 300 g of concentrated hydrochloric acid and 90 g of steel shavings into a galeliFtny apparatus equipped with a thermostating jacket and a layer of insulation. Hot water is fed into the jacket and the temperature in the reaction zone is brought to 65 s. The reaction is carried out for 30 minutes. during the continuous circulation of the reaction mass due to the supply of nitrogen to the bot- tom part of the reactor. A solution containing 9.9% ferric chloride (11) is obtained. To speed up the chip dissolution process, the resulting solution is treated with exhaust gases containing chlorine and hydrogen chloride. The exhaust gases are served in the amount of 80 m / min for 60 minutes. The composition of gases,%: 34,0; ne 30.7; nitrogen 35.27; chlorobenzene 0.03. The temperature in the reactor 6570e. 80 ml of water was added to dilute the solution. The result is 525 g of a solution having a composition, wt.%: FeCKj 4,3; 35, her 2.5; water 58.1. The resulting solution, in an amount of 400 g, is left in the reactor, the heating is stopped and the exhaust gases are fed in an amount of 0.241 L / min. The composition of the gases, vol.%: Ce 34.0; HCg 30.7; nitrogen 35.27; chlorobenzene 0.03. The process is conducted at the time of the experiment 4 h 50 min Steel chips are loaded periodically as they are triggered. In total, 79.5 g of chips were reacted for the experience. 165 liters of water was added to dilute the solution. As a result of the experiment, 754.8 g of a solution having a composition, wt.%: FeCf) 2.9; FeCS 38.0; NS 1.4; water 7.7. The chlorobenzene content is 3.2 mg / l. In the exhaust gases at the inlet of the gas-lift apparatus, the concentration of chlorobenzene is 0.07% by volume, hydrogen is 28% by volume, chlorine and hydrogen chloride are absent. In order to avoid the formation of an explosive concentration of hydrogen, the exhaust gases are diluted directly at the outlet of the apparatus to a hydrogen concentration of 2-2.5% by volume. For chlorination with pure chlorine, 348 g of the solution of the composition, vol.% Were used: Reze 38.0; FeCg 2.9; HSP 1.4; water 57.7. The chlorobenzene content is 3.2 mg / l, the chlorine consumption in the chlorinator is 0.170 l / min. Chlorination time is 1 hour and 15 minutes, the process is carried out at 75-80 e. 383 g of a solution is obtained having a composition, wt%: Recovery 45,4; PeCgy 0.9; not 1.5; water 52.2. The chlorobenzene content is 2.1 mg / l. The amount of chlorine in exhaust gases at the exit of the pre-chlorinator. varies from 0 to 0.04 l / min. In total, 4.8 g of chlorine is absorbed from the exhaust gases. In the operation of the Stripping take the solution after the pre-chloro in the amount of 382, Composition, wt.%: FeCS 45,4; ReС 0.9; neb 1,5; water is 52.2, chlorobenzene content is 2.1 mg / l. Purging is carried out with air at a rate of 0.150 l / min at 80-85 ° C. Purge time 20 min. The target product received 381 g, weight, wt.%: FeCS 45,4; 0.82; neb 1,5; water 52.1. Chlorobenzene is not detected. The product meets the requirements of TU 6-01-1-192-79. Example 2. In a gas-lift apparatus equipped with a thermostatic jacket and an insulation layer, 300 ml of concentrated hydrochloric acid and 85 g of steel chips are loaded. Hot water is fed into the jacket and the temperature in the reaction zone is adjusted to 65 °. The reaction is carried out for 40 m-in with the continuous circulation of the reaction mass by supplying nitrogen to the bubbling part of the reactor. Get a solution containing 12.4 wt.%. ferric chloride (11). To speed up the chip dissolution process, the resulting solution is treated with exhaust gases containing chlorine and hydrogen chloride. Exhaust gases are given in the amount of 80 ml / min for 60 minutes. The composition of the exhaust gases,%: 34.0; ne 30.7; nitrogen 35.27; chlorobenzene 0.03. Temperature in the reactor is 65-70 ° C. 50 ml of water is added to dilute the solution. As a result, 493 g of a solution is obtained having a composition, wt%: FecKj 5.3 Fece 34.3; NSV 2.9; water 57.5. The resulting solution in the amount of 449.8 g is left in the reactor, the heating is stopped and the exhaust gases are supplied in the amount of 0.241 l / m. The composition of the exhaust gases,%: 34.0; hydrogen chloride 30.7; nitrogen 35.3; chlorobenzene 0.041. The process is carried out at 80 C. Experience time is 5 hours. For the experience 56.7 g of steel shavings reacted, 160 g of water was added. As a result of the experience, 780.6 g of solvent was obtained, containing, by weight, wt. Fece 2.9; ReSBG 38.0; NSE 1.3; water 57.8. The chlorobenzene content is 4.1 mg / l. Chlorine and HCP are absent in exhaust gases, chlorobenzene content is 0.11% by volume, hydrogen is 28% by volume. For chlorination with pure chlorine, 370 g of the composition solution, wt.% ReСВз 2.9; FeCB 38.0; HsD 1.3; water 57.8. The chlorobenzene content is 4.1 mg / l, the chlorine consumption is 0.170 l / min, and the chlorination time is 1 h 18 min. The process is conducted at 75-80 ° C. Received 407.0 g of solution, containing, wt.% ReSvz 43.3; FeCPg 0.81; HC8 1.4; in yes 54,6. The chlorobenzene content is 2.8 mg / l. 4.9 g of chlorine was extracted from exhaust gases. The whole solution after chlorination is subjected to a nitrogen stripping at 80-85 ° C and a nitrogen feed rate of 10.150 l / min. Purge time 20 min. The target product obtained 405.8 g. Composition, wt.%: 43,4; FeCCg O HCC 1.3; water 54.4. Chlorobenzene is not about | aruzhen. The product meets the requirements of TU 6-01-1-192-79. Example 3 (comparative) A gas-lift apparatus (analogous to that used in Example 1) is loaded with 400 g of absorbent having a composition, in wt%: ReСР 35.1; 4.3; ne 2.5; water 58.1. in the amount of 0.241 l / min. Composition of gases, Vol.%: 34.0; HC (30.7; N 35.3; chlorobenzene 0.03. A solution of ReCY (identical to the initial solution) in an amount of 3.0 ml / minutes In total, 1129 g of solution was introduced for the experiment, the time of the experiment was 4 hours and 50 minutes, the result of the experiment was 1634.1 g of the solution, its composition, wt%: Fece 23.6; FeC 17.5; ne 3.0; water 55.0. Chlorine benzene content 6.5 mg / l In exhaust gases at the exit The apparatus has chlorobenzene concentration of 0.07% by volume, chlorine on average 6-6.5% by volume, hydrogen chloride is absent. The temperature in the device was kept at 50-55 C. Example 4 (comparative). In a gas-lift type device (similar - used in example 1), 861 g of FeC solution having the composition, wt%: FeC 42.5; FeCfg HC 1.5; water 55.1 and 79.5 g steel chips are loaded in. Next, hot water is fed into the heat exchange jacket and conduct the process at 60-70 s for 9 h 20 min. To speed up the process, 6 g of concentrated hydrochloric acid was added during the test. as a result of the experiment, 910.6 g of a solution is obtained having a composition, wt%: FecK 33.0; Fece3 13.36; NS 1.33; water 52.31. 35.8 g unreacted chips are discharged. As can be seen from the above examples, the absorption of chlorine and hydrogen chloride containing gases in the presence of iron chips can increase the purity of the product (the chlorobenzene content has decreased by half), which is associated with organic stripping and temperature increase process. In addition, the process speed doubles while reducing energy costs. The latter is provided with the exception of heating at the recovery stage.

Claims (2)

1. METHOD FOR PRODUCING A SOLUTION OF IRON CHLORIDE (111), including dissolving iron chips in hydrochloric acid, absorbing the resulting solution of gases containing chlorine and hydrogen chloride, and subsequent processing of the solution with chlorine, characterized in that, in order to increase the frequency of the product, accelerate the process and reduce energy consumption, the absorption of gases containing chlorine and hydrogen chloride, is carried out in the presence of iron chips. 2. SpoOob pop. 1, characterized in that the absorption of gases containing chlorine and hydrogen chloride is carried out at 80-85 ° C. $