Electrolyte for preparing ferric chloride and ferrous chloride as well as preparation method and application of electrolyte

Abstract

The invention belongs to the technical field of inorganic chemical industry, and particularly relates to an electrolyte for preparing ferric chloride and ferrous chloride as well as a preparation method and application thereof. The electrolyte is prepared from the following raw materials in parts by weight: 15 to 35 parts of vinylene carbonate, 0.1 to 0.2 part of ammonium chloride solution, 0.1 to 0.3 part of hydrazine dihydrochloride solution and 1 to 5 parts of water. The preparation method of ferric chloride and ferrous chloride comprises the following steps: (1) adding metallic iron into a reaction tank, and connecting the metallic iron with a positive electrode of a power supply; introducing oxygen, and opening a scrubber tower; adding electrolyte into the reaction tank, starting a rectifier, and introducing current and voltage; and (3) concentrating and crystallizing the obtained liquid to obtain the product. The preparation method disclosed by the invention is safe, low in energy consumption, high in yield and suitable for industrial requirements.

Description

Technical Field

[0001] The invention belongs to the technical field of inorganic chemical industry, and particularly relates to an electrolyte for preparing ferric chloride and ferrous chloride, a preparation method and application thereof. Background Art

[0002] In traditional production methods, ferrous chloride is prepared by iron and hydrochloric acid through replacement reaction, or by iron and ferric chloride solution generation redox reaction to obtain. Ferric chloride is then generally made by iron and chlorine through high temperature reaction directly to obtain solid product or by ferrous chloride and oxidant (such as chlorine, oxygen, superoxide etc.) generation oxidation reaction, obtain liquid product. Iron powder and hydrochloric acid generation violent chemical reaction, release heat and hydrogen, control conditions are not suitable and very easy to explode and cause casualties, in addition, ferrous ion is very easily oxidized to ferric iron at higher temperatures, easily causes ferric iron hydrolysis when acidity is insufficient, product turns yellow, is difficult for storage, and is difficult to obtain high-purity ferrous chloride crystals.

[0003] Currently, existing related technologies have improved traditional methods and solved safety issues, but the energy consumption is high. For example, Chinese patent CN119822418A discloses a method for preparing a stable, safe and reliable iron chloride product, which relates to the technical field of inorganic compound ferric chloride and ferrous chloride. The preparation method of the present invention comprises the following steps: iron and hydrochloric acid are subjected to an electric field in a device to change the electrochemical potential so that the iron undergoes chemical replacement and electrochemical reaction, so that the iron is directly dissolved in the acid to form ferrous chloride or ferric chloride. By controlling the reaction conditions, the flammable and explosive hydrogen produced in the general replacement reaction is avoided, which greatly improves the safety of the chemical process and reduces the requirements for production conditions. At the same time, the reaction speed can be accelerated, and the reaction is carried out thoroughly, thereby improving the reaction efficiency and the utilization rate of raw materials and equipment. The obtained solution can be obtained by methods such as concentration and crystallization to obtain a solid product.

[0004] As Chinese patent CN110980833A discloses a preparation method of electronic-grade ferrous chloride. Its purpose is to provide a production method of electronic-grade ferrous chloride that is simple in production principle, has a wide range of raw material sources, is low in cost and is easy to industrialized production. This invention is pre-treated and the iron-containing waste hydrochloric acid reduced and impurity-removed is put into a triple-effect evaporation system for evaporation concentration, and then four water ferrous chloride crystals are obtained through cooling and centrifugation. If crystallization does not reach the control index of electronic-grade ferrous chloride, multiple recrystallization methods are used until the electronic-grade ferrous chloride that reaches the control standard is obtained, and the mother liquor after centrifugation can be directly used in the production of water treatment agent ferric chloride, and the whole process does not produce secondary pollutants. At the same time, it is avoided that ferrous ion in traditional production process is easily oxidized to ferric iron at higher temperatures and acidity is not enough and easily causes ferric iron hydrolysis, product yellowing, is difficult for storage and other deficiencies. But this invention also has the problems mentioned above, and process complexity.

[0005] Therefore, there is an urgent need to study a method for electrolytic preparation of ferric chloride and ferrous chloride that is simple in preparation, low in energy consumption, and safe in production. Summary of the Invention

[0006] To address the deficiencies of the prior art, the present invention provides an electrolyte for preparing ferric chloride and ferrous chloride, as well as a preparation method and application thereof. The electrolytic preparation method of ferric chloride and ferrous chloride provided by the present invention improves upon the prior art by adding the corresponding electrolyte during the electrolysis process, thereby reducing energy consumption, increasing yield, and ensuring safe operation.

[0007] To achieve the above object, the present invention adopts the following technical solutions: On the one hand, the present invention provides an electrolyte for preparing ferric chloride and ferrous chloride, which includes the following raw materials in parts by weight: 15-35 parts of vinylene carbonate, 0.1-0.2 parts of ammonium chloride solution, 0.1-0.3 parts of hydrazine dihydrochloride solution and 1-5 parts of water.

[0008] Preferably, the mass ratio of the vinylene carbonate, ammonium chloride solution and hydrazine dihydrochloride solution is 20-30:0.15:0.2.

[0009] Further preferably, the electrolyte comprises the following raw materials in parts by weight: 25 parts of vinylene carbonate, 0.15 parts of ammonium chloride solution, 0.2 parts of hydrazine dihydrochloride solution and 2 parts of water.

[0010] Preferably, the concentration of vinylene carbonate is 0.05-0.15 mol / L, more preferably 0.08 mol / L.

[0011] Preferably, the concentration of the hydrazine dihydrochloride solution is 0.1-0.5 mol / L, more preferably 0.25 mol / L.

[0012] Preferably, the concentration of the ammonium chloride solution is 0.2-0.6 mol / L, more preferably 0.5 mol / L.

[0013] Preferably, the electrolyte is prepared by mixing the raw materials in a uniform ratio.

[0014] On the other hand, the present invention also provides a method for preparing ferric chloride and ferrous chloride, comprising the following steps: (1) Add metallic iron to the reaction tank 5 and connect the iron to the positive electrode of the power supply; open the liquid oxygen storage tank 2, introduce oxygen, and open the scrubber 10; (2) Add electrolyte to the reaction cell 5, open the evaporator 3, open the hydrochloric acid storage tank 1, start the rectifier 4, and pass current and voltage of 2.2V; (3) Open the transfer tank 8, collect the liquid obtained from the mother liquid tank 6, evaporate and concentrate it through the mother liquid pump 7, and crystallize it in the crystallizer 9 to obtain the product.

[0015] Preferably, the current is 3000-7000A and the current density is 400-935A / mm 2 .

[0016] More preferably, the current is 6000A and the current density is 800A / mm 2 .

[0017] Preferably, the voltage is 2-3V, more preferably 2.2V.

[0018] Finally, the present invention also provides the application of ferric chloride and ferrous chloride prepared by the above preparation method in industrial production.

[0019] Compared with the prior art, the present invention has the following beneficial effects: (1) The present invention reduces energy consumption and improves the yield of ferric chloride and ferrous chloride by controlling the ratio of each component in the electrolyte.

[0020] (2) The preparation method of the present invention is safe and produces almost no hydrogen, thus avoiding the possibility of hydrogen explosion. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is a flow chart of the preparation method of ferric chloride and ferrous chloride of the present invention; Among them, 1. Hydrochloric acid storage tank, 2. Liquid oxygen storage tank, 3. Evaporator, 4. Rectifier, 5. Reaction tank, 6. Mother liquor storage tank, 7. Mother liquor pump, 8. Diluted liquid storage tank, 9. Crystallizer, 10. Scrubber. DETAILED DESCRIPTION

[0022] The technical solution of the present invention is described clearly and completely below with specific embodiments. Obviously, the embodiments described are only some embodiments of the present invention, rather than all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative work are within the scope of protection of the present invention. Unless otherwise specified, the materials and reagents used are commercially available reagents and materials.

[0023] In the following examples and comparative examples, the concentration of vinylene carbonate is 0.08 mol / L; the concentration of the hydrazine dihydrochloride solution is 0.25 mol / L; and the concentration of the ammonium chloride solution is 0.5 mol / L.

[0024] The sources of the raw materials in the following examples and comparative examples are shown in Table 1 below: Table 1

[0025] Example 1 An electrolyte for preparing ferric chloride and ferrous chloride is composed of the following raw materials in parts by weight: 25 parts of vinylene carbonate, 0.15 parts of ammonium chloride solution, 0.2 parts of hydrazine dihydrochloride solution and 2 parts of water.

[0026] The preparation method of the ferric chloride and ferrous chloride is as follows: (1) Add 30 kg of metallic iron to the reaction tank 5 and connect the iron to the positive electrode of the power supply; open the liquid oxygen storage tank 2, introduce oxygen, and open the scrubber 10; (2) Add 50 kg of the above electrolyte to the reaction cell 5, open the evaporator 3, start the rectifier 4, and pass a current of 6000 A with a current density of 800 A / mm 2 and voltage 2.2V, open hydrochloric acid tank 1 (containing 200kg hydrochloric acid); (3) Open the dilute liquid storage tank 8, collect the liquid obtained from the mother liquid storage tank 6, evaporate and concentrate it through the mother liquid pump 7, and crystallize it in the crystallizer 9 to obtain the product.

[0027] Example 2 An electrolyte for preparing ferric chloride and ferrous chloride is composed of the following raw materials in parts by weight: 15 parts of vinylene carbonate, 0.1 parts of ammonium chloride solution, 0.1 parts of hydrazine dihydrochloride solution and 1 part of water. The preparation method of the ferric chloride and ferrous chloride is as follows: (1) Add 30 kg of metallic iron to the reaction tank 5 and connect the iron to the positive electrode of the power supply; open the liquid oxygen storage tank 2, introduce oxygen, and open the scrubber 10; (2) Add 50 kg of the above electrolyte to the reaction cell 5, open the evaporator 3, start the rectifier 4, and pass a current of 3000 A with a current density of 400 A / mm 2 and voltage 3V, open hydrochloric acid tank 1 (containing 200kg hydrochloric acid); (3) Open the dilute liquid storage tank 8, collect the liquid obtained from the mother liquid storage tank 6, evaporate and concentrate it through the mother liquid pump 7, and crystallize it in the crystallizer 9 to obtain the product.

[0028] Example 3 An electrolyte for preparing ferric chloride and ferrous chloride is composed of the following raw materials in parts by weight: 35 parts of vinylene carbonate, 0.2 parts of ammonium chloride solution, 0.3 parts of hydrazine dihydrochloride solution and 5 parts of water. The preparation method of the ferric chloride and ferrous chloride is as follows: (1) Add 30 kg of metallic iron to the reaction tank 5 and connect the iron to the positive electrode of the power supply; open the liquid oxygen storage tank 2, introduce oxygen, and open the scrubber 10; (2) Add 50 kg of the above electrolyte to the reaction cell 5, open the evaporator 3, start the rectifier 4, and pass a current of 7000 A with a current density of 933 A / mm 2 and voltage 2V, open hydrochloric acid tank 1 (containing 200kg hydrochloric acid); (3) Open the dilute liquid storage tank 8, collect the liquid obtained from the mother liquid storage tank 6, evaporate and concentrate it through the mother liquid pump 7, and crystallize it in the crystallizer 9 to obtain the product.

[0029] Comparative Example 1 The difference from Example 1 is that 25 parts of vinylene carbonate are replaced by 25 parts of ammonium chloride solution, and the rest are the same as Example 1.

[0030] Comparative Example 2 The difference from Example 1 is that 0.1 part of ammonium chloride solution is replaced by 0.1 part of vinylene carbonate, and the rest is the same as Example 1.

[0031] Comparative Example 3 The difference from Example 1 is that the weight ratio is different, namely: 10 parts of vinylene carbonate, 0.3 parts of ammonium chloride solution, 0.2 parts of hydrazine dihydrochloride solution and 2 parts of water. The rest is the same as Example 1.

[0032] Comparative Example 4 The difference from Example 1 is that the ammonium chloride solution is replaced by a potassium chloride solution (concentration is 0.5 mol / L), and the rest is the same as Example 1.

[0033] Comparative Example 5 The difference from Example 1 is that electrolysis is performed according to the method of Example 4 of patent CN119822418A, specifically as follows: The preparation method of the ferric chloride and ferrous chloride is as follows: (1) Add 30 kg of metallic iron to the reaction tank 5 and connect the iron to the positive electrode of the power supply; open the liquid oxygen storage tank 2, introduce oxygen, and open the scrubber 10; (2) Add 50 kg of the above electrolyte to the reaction cell 5, open the evaporator 3, start the rectifier 4, and pass a current of 6000 A with a current density of 800 A / mm 2 and voltage 3.54V, open hydrochloric acid tank 1 (containing 200kg hydrochloric acid); (3) Open the dilute liquid storage tank 8, collect the liquid obtained from the mother liquid storage tank 6, evaporate and concentrate it through the mother liquid pump 7, and crystallize it in the crystallizer 9 to obtain the product.

[0034] Effect experiment The preparation methods of Examples 1-3 and Comparative Examples 1-4 were continued for 4 hours. The production of ferrous chloride and ferric chloride was determined according to the methods 7.3 and 7.4 of the national standard "GB / T1621-2023". The oxygen consumption was counted, and the amount of remaining iron and hydrochloric acid was weighed to obtain the consumption of iron and hydrochloric acid. The results are shown in Table 2 below.

[0035] Table 2

[0036] As can be seen from the data in Table 2, compared with patent CN119822418A, by adding the electrolyte prepared by the present invention and controlling the composition and ratio of the electrolyte, the generation of ferric chloride and ferrous chloride is increased, the voltage does not exceed 3V, and energy consumption is greatly reduced. As can be seen from Comparative Example 5 and Example 1, even if the voltage is increased from 2.2V to 3.52V, the generation of ferric chloride and ferrous chloride does not increase, which shows that the present invention not only saves energy consumption but also increases output, and does not produce hydrogen, and there is no safety hazard.

[0037] The above detailed description is a specific description of one feasible embodiment of the present invention. This embodiment is not intended to limit the patent scope of the present invention. Any equivalent implementation or modification that does not depart from the present invention should be included in the scope of the technical solution of the present invention.

Claims

1. An electrolyte for preparing ferric chloride and ferrous chloride, characterized in that: The following raw materials are included in parts by weight: 15-35 parts of vinylene carbonate, 0.1-0.2 parts of ammonium chloride solution, 0.1-0.3 parts of hydrazine dihydrochloride solution and 1-5 parts of water.

2. The electrolyte according to claim 1, characterized in that The mass ratio of the vinylene carbonate, the ammonium chloride solution and the hydrazine dihydrochloride solution is 20-30:0.15:0.

2.

3. The electrolyte according to claim 1, characterized in that The following raw materials are included in parts by weight: 25 parts of vinylene carbonate, 0.15 parts of ammonium chloride solution, 0.2 parts of hydrazine dihydrochloride solution and 2 parts of water.

4. A method for preparing ferric chloride and ferrous chloride, characterized in that: The following steps are involved: (1) Add metallic iron to the reaction cell, connect the iron to the positive electrode of the power supply, and introduce oxygen; (2) adding the electrolyte according to any one of claims 1 to 3 into the reaction cell, applying current and voltage, and introducing hydrochloric acid; (3) The liquid obtained in step (2) is evaporated, concentrated, and crystallized to obtain the product.

5. The preparation method according to claim 4, characterized in that The current in step (2) is 3000-7000A, and the current density is 400-935A / mm 2 .

6. The preparation method according to claim 5, characterized in that The current in step (2) is 6000A and the current density is 800A / mm 2 .

7. The preparation method according to claim 4, characterized in that The voltage in step (2) is 2-3V.

8. The preparation method according to claim 7, characterized in that The voltage in step (2) is 2.2V.

9. Ferric chloride and ferrous chloride obtained by the preparation method according to any one of claims 4 to 8.

10. Use of the electrolyte according to any one of claims 1 to 3 in the preparation of ferric chloride and ferrous chloride.

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