Preparation process and application of ferric trichloride

Abstract

The invention discloses a preparation process and application of ferric trichloride, and relates to the field of inorganic chemistry. In the preparation process of the ferric trichloride, the steel pickling waste liquid is firstly filtered, the pH value is adjusted, then the steel pickling waste liquid reacts with iron powder, then biochemical oxidation is carried out through a fixed bed, in-situ electrochemical chlorine circulation is carried out, and finally concentration, impurity removal and compounding with a stabilizer are carried out, so that the liquid ferric trichloride is prepared. The preparation process of the ferric trichloride has the characteristics of low energy consumption, greenness, high purity and difficulty in devitrification and hydrolysis.

Description

Technical Field

[0001] This invention relates to the field of inorganic chemistry, specifically to a process for preparing ferric chloride and its application. Background Technology

[0002] Currently, the industrial processes for preparing ferric chloride can be broadly categorized as follows: high-temperature dry ferric chloride / ferric oxide processing; hydrochloric acid leaching of iron filings followed by chlorination / hydrogen peroxide wet oxidation; acid pickling waste regeneration; and electrochemical anodic iron dissolution, all of which have been commercialized.

[0003] However, the high-temperature dry ferric chloride / ferric oxide method has high energy consumption, high material cost, and high risk factor; the hydrochloric acid leaching-wet oxidation method has high raw material cost and low purity; the acid washing waste acid regeneration-chlorine-oxygen method has a high risk factor and is prone to hydrolysis; the electrochemical anodic iron dissolution-chlorine regeneration method has high energy consumption. Therefore, this application introduces a method with low energy consumption, low cost, and is not prone to crystallization and hydrolysis. Summary of the Invention

[0004] The purpose of this invention is to provide a process for preparing ferric chloride and its application, so as to solve the problems existing in the prior art.

[0005] A process for preparing ferric chloride, wherein the process involves filtering and adjusting the pH of steel pickling waste liquid, reacting it with iron powder, then using fixed-bed biochemical oxidation, followed by in-situ electrochemical chlorine circulation, and finally concentrating, removing impurities, and compounding it with a stabilizer to obtain liquid ferric chloride.

[0006] The stabilizers are phosphorous acid, hydroxyethylidene diphosphonic acid, and imidazoline derivatives.

[0007] Preferably, the ferric chloride preparation process mainly includes the following preparation steps:

[0008] (1) Mix steel pickling waste liquid with 60 mesh quartz sand at a mass ratio of 8~12:1, sonicate for 10~14 min, filter, adjust the pH to 1.8~2 with calcium hydroxide aqueous solution to obtain steel pickling waste liquid treatment liquid pretreatment liquid, mix steel pickling waste liquid treatment liquid pretreatment liquid with iron powder at a mass ratio of 30~32:1, stir at 38~42℃ and 200~300r / min for 1.5~1.7h, filter, take the filtrate to obtain steel pickling waste liquid treatment liquid;

[0009] (2) The steel pickling waste liquid is treated by fixed-bed biochemical oxidation. The reactor material is a steel cylinder lined with polyvinylidene fluoride, the packing material is volcanic rock ceramsite with a diameter of 5~15mm, the microorganism is a single strain with the preservation number CGMCC No.XX "AF-2025", the reaction temperature is 30~35℃, the residence time is 3.8~4.2h, and the biochemical effluent is obtained.

[0010] (3) Using the biochemical effluent as the electrolyte, an in-situ electrochemical chlorine cycle was carried out at a reaction temperature of 35~45°C to obtain a chlorine cycle treatment solution;

[0011] (4) Concentrate the chlorine recycling solution and then remove impurities to obtain a concentrated solution;

[0012] (5) The concentrated solution, phosphorous acid, hydroxyethylidene diphosphonic acid and imidazoline derivative are mixed evenly in a mass ratio of 98.7~99.4:0.5~1.0:0.05~0.2:0.05~0.1 to obtain liquid ferric chloride.

[0013] Preferably, the main components and concentrations of the steel pickling waste liquid in step (1) are as follows: ferrous chloride Free hydrogen chloride 6~12wt%, copper ions 0~200ppm, nickel ions 0~120ppm.

[0014] Preferably, the mass fraction of the calcium hydroxide aqueous solution in step (1) is 9% to 11%.

[0015] Preferably, the cathode of the in-situ electrochemical chlorine cycle in step (3) is a 316L stainless steel plate, and the anode is... electrode.

[0016] Preferably, the current density of the in-situ electrochemical chlorine cycle in step (3) is .

[0017] Preferably, the concentration operation in step (4) is to dry at 88~92℃ and 34~36kPa for 1~1.2h.

[0018] Preferably, the impurity removal in step (4) is carried out using an activated carbon tower.

[0019] An application of ferric chloride, wherein the application of ferric chloride prepared by the aforementioned ferric chloride preparation process is in drinking water treatment, urban sewage purification, industrial wastewater purification, etc.

[0020] Compared with the prior art, the beneficial effects achieved by the present invention are:

[0021] In the preparation process of ferric chloride, the present invention first filters and adjusts the pH of steel pickling waste liquid, then reacts it with iron powder, then uses fixed-bed biochemical oxidation, then in-situ electrochemical chlorine circulation, and finally concentrates, removes impurities, and combines it with a stabilizer to obtain liquid ferric chloride.

[0022] First, the steel pickling waste liquid is filtered and its pH is adjusted before reacting with iron powder. The reaction with iron powder removes heavy metal ions from the waste liquid and further increases the concentration of ferrous ions in the waste liquid without introducing other impurities. Low-temperature fixed-bed biochemical oxidation and in-situ electrochemical chlorine circulation are used to reduce heat consumption. At the same time, due to the use of in-situ electrochemical chlorine circulation, chlorine gas forms a closed loop. Chlorine gas is generated in-situ at the anode and consumed immediately, reducing chemical costs. Meanwhile, chloride ions circulate within the system, and the accumulation of by-product salts is controlled, avoiding subsequent salt discharge or dilution release.

[0023] Secondly, the absence of high-temperature slag and acid mist injection results in lower concentrations of chlorine and hydrogen chloride emissions compared to traditional processes, meeting the latest atmospheric emission control requirements and ensuring a green and safe production process throughout. Furthermore, the use of waste acid as raw material reduces production costs and achieves green recycling. After impurity removal treatment, the purity of the product is further improved.

[0024] Finally, when combined with a stabilizer, the resulting ferric chloride becomes stable and less prone to crystallization and hydrolysis. Detailed Implementation

[0025] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0026] The main components and concentrations of the steel pickling waste liquid described in the following examples and comparative examples are as follows: ferrous chloride Free hydrogen chloride 9 wt%, copper ions 100 ppm, nickel ions 60 ppm.

[0027] Example 1

[0028] A process for preparing ferric chloride mainly includes the following preparation steps:

[0029] (1) Mix steel pickling waste liquid with 60 mesh quartz sand at a mass ratio of 8:1, sonicate for 10 min, filter, adjust the pH to 1.8 with 9% calcium hydroxide aqueous solution to obtain steel pickling waste liquid pretreatment solution, mix steel pickling waste liquid pretreatment solution with iron powder at a mass ratio of 30:1, stir at 38℃ and 200 r / min for 1.5 h, filter, take the filtrate to obtain steel pickling waste liquid treatment solution;

[0030] (2) The steel pickling waste liquid is treated by fixed-bed biochemical oxidation. The reactor material is a steel cylinder lined with polyvinylidene fluoride, the packing material is volcanic rock ceramsite with a diameter of 5 mm, the microorganism is a single strain with the preservation number CGMCC No.XX "AF-2025", the reaction temperature is 30℃, the residence time is 3.8h, and the biochemical effluent is obtained.

[0031] (3) Using the biochemical effluent as the electrolyte, an in-situ electrochemical chlorine cycle was performed. The cathode was a 316L stainless steel plate, and the anode was... Electrode, current density The reaction temperature was 35°C, and a chlorine recycling solution was prepared.

[0032] (4) The chlorine circulating treatment liquid was dried at 88℃ and 34kPa for 1h, and then impurities were removed by using an activated carbon tower to obtain a concentrated liquid;

[0033] (5) The concentrated solution, phosphorous acid, hydroxyethylidene diphosphonic acid and imidazoline derivative were mixed evenly in a mass ratio of 98.7:0.5:0.05:0.05 to obtain liquid ferric chloride.

[0034] Example 2

[0035] A process for preparing ferric chloride mainly includes the following preparation steps:

[0036] (1) Mix steel pickling waste liquid with 60 mesh quartz sand at a mass ratio of 8:1, sonicate for 14 min, filter, adjust the pH to 1.8 with 9% calcium hydroxide aqueous solution to obtain steel pickling waste liquid pretreatment solution, mix steel pickling waste liquid pretreatment solution with iron powder at a mass ratio of 30:1, stir at 38℃ and 200 r / min for 1.7 h, filter, take the filtrate to obtain steel pickling waste liquid treatment solution;

[0037] (2) The steel pickling waste liquid is treated by fixed-bed biochemical oxidation. The reactor material is a steel cylinder lined with polyvinylidene fluoride, the packing material is volcanic rock ceramsite with a diameter of 5 mm, the microorganism is a single strain with the preservation number CGMCC No.XX "AF-2025", the reaction temperature is 30℃, the residence time is 4.2 h, and the biochemical effluent is obtained.

[0038] (3) Using the biochemical effluent as the electrolyte, an in-situ electrochemical chlorine cycle was performed. The cathode was a 316L stainless steel plate, and the anode was... Electrode, current density is The reaction temperature was 35°C, and a chlorine recycling solution was prepared.

[0039] (4) The chlorine circulating treatment liquid was dried at 88℃ and 34kPa for 1.2h, and then impurities were removed by using an activated carbon tower to obtain a concentrated liquid;

[0040] (5) The concentrated solution, phosphorous acid, hydroxyethylidene diphosphonic acid and imidazoline derivative were mixed evenly in a mass ratio of 98.7:0.5:0.05:0.05 to obtain liquid ferric chloride.

[0041] Example 3

[0042] A process for preparing ferric chloride mainly includes the following preparation steps:

[0043] (1) Mix steel pickling waste liquid with 60 mesh quartz sand at a mass ratio of 10:1, sonicate for 12 min, filter, adjust the pH to 1.9 with a 10% calcium hydroxide aqueous solution to obtain steel pickling waste liquid pretreatment solution, mix steel pickling waste liquid pretreatment solution with iron powder at a mass ratio of 31:1, stir at 40℃ and 250 r / min for 1.6 h, filter, take the filtrate to obtain steel pickling waste liquid treatment solution;

[0044] (2) The steel pickling waste liquid is treated by fixed-bed biochemical oxidation. The reactor material is a steel cylinder with polyvinylidene fluoride lining, the packing material is volcanic rock ceramsite with a diameter of 10 mm, the microorganism is a single strain with accession number CGMCC No.XX "AF-2025", the reaction temperature is 32.5℃, the residence time is 4h, and the biochemical effluent is obtained.

[0045] (3) Using the biochemical effluent as the electrolyte, an in-situ electrochemical chlorine cycle was performed. The cathode was a 316L stainless steel plate, and the anode was... Electrode, current density The reaction temperature was 40°C, and a chlorine recycling solution was prepared.

[0046] (4) The chlorine circulation treatment liquid was dried at 90℃ and 35kPa for 1.1h, and then purified by an activated carbon tower to obtain a concentrated liquid;

[0047] (5) The concentrated solution, phosphorous acid, hydroxyethylidene diphosphonic acid and imidazoline derivative were mixed evenly in a mass ratio of 99.05:0.75:0.125:0.075 to obtain liquid ferric chloride.

[0048] Example 4

[0049] A process for preparing ferric chloride mainly includes the following preparation steps:

[0050] (1) Mix steel pickling waste liquid with 60 mesh quartz sand at a mass ratio of 12:1, sonicate for 10 min, filter, adjust the pH to 2 with 11% calcium hydroxide aqueous solution to obtain steel pickling waste liquid pretreatment solution, mix steel pickling waste liquid pretreatment solution with iron powder at a mass ratio of 32:1, stir at 42℃ and 300 r / min for 1.5 h, filter, take the filtrate to obtain steel pickling waste liquid treatment solution;

[0051] (2) The steel pickling waste liquid is treated by fixed-bed biochemical oxidation. The reactor material is a steel cylinder lined with polyvinylidene fluoride, the packing material is volcanic rock ceramsite with a diameter of 15 mm, the microorganism is a single strain with the preservation number CGMCC No.XX "AF-2025", the reaction temperature is 35℃, the residence time is 3.8h, and the biochemical effluent is obtained.

[0052] (3) Using the biochemical effluent as the electrolyte, an in-situ electrochemical chlorine cycle was performed. The cathode was a 316L stainless steel plate, and the anode was... Electrode, current density is The reaction temperature was 45°C, and a chlorine recycling solution was prepared.

[0053] (4) The chlorine circulation treatment liquid was dried at 92°C and 36 kPa for 1 h, and then impurities were removed by using an activated carbon tower to obtain a concentrated liquid;

[0054] (5) The concentrated solution, phosphorous acid, hydroxyethylidene diphosphonic acid and imidazoline derivative were mixed evenly in a mass ratio of 99.4:1.0:0.2:0.1 to obtain liquid ferric chloride.

[0055] Example 5

[0056] A process for preparing ferric chloride mainly includes the following preparation steps:

[0057] (1) Mix steel pickling waste liquid with 60 mesh quartz sand at a mass ratio of 12:1, sonicate for 14 min, filter, adjust the pH to 2 with 11% calcium hydroxide aqueous solution to obtain steel pickling waste liquid pretreatment solution, mix steel pickling waste liquid pretreatment solution with iron powder at a mass ratio of 32:1, stir at 42℃ and 300 r / min for 1.7 h, filter, take the filtrate to obtain steel pickling waste liquid treatment solution;

[0058] (2) The steel pickling waste liquid is treated by fixed-bed biochemical oxidation. The reactor material is a steel cylinder lined with polyvinylidene fluoride, the packing material is volcanic rock ceramsite with a diameter of 15 mm, the microorganism is a single strain with the preservation number CGMCC No.XX "AF-2025", the reaction temperature is 35℃, the residence time is 4.2 h, and the biochemical effluent is obtained.

[0059] (3) Using the biochemical effluent as the electrolyte, an in-situ electrochemical chlorine cycle was performed. The cathode was a 316L stainless steel plate, and the anode was... Electrode, current density The reaction temperature was 45°C, and a chlorine recycling solution was prepared.

[0060] (4) The chlorine circulation treatment liquid was dried at 92℃ and 36kPa for 1.2h, and then impurities were removed by using an activated carbon tower to obtain a concentrated liquid;

[0061] (5) The concentrated solution, phosphorous acid, hydroxyethylidene diphosphonic acid and imidazoline derivative were mixed evenly in a mass ratio of 99.4:1.0:0.2:0.1 to obtain liquid ferric chloride.

[0062] Comparative Example 1

[0063] A process for preparing ferric chloride, which uses the traditional wet chlorination route.

[0064] Test Example 1

[0065] Test method: Test Conversion rate, chlorine consumption, total power consumption, and steam heat consumption, where chlorine consumption = chlorine mass / ferric chloride mass produced, total power consumption is the power consumption to produce 1 kg of ferric chloride, and steam heat consumption is the heat consumption to produce 1 kg of ferric chloride, are tested according to GB / T4482-2018. and The concentrations were determined. The results are shown in Table 1.

[0066] Table 1 Statistics on conversion rate, cost, and energy consumption

[0067] <![CDATA[Fe 2+ →Fe 3+ Conversion rate Chlorine usage Total power consumption Steam heat consumption Example 1 99.3% 0.09 1.15 kWh 1.71MJ Example 2 99.6% 0.08 1.13 kWh 1.70MJ Example 3 99.5% 0.07 1.14 kWh 1.69MJ Example 4 99.4% 0.07 1.11 kW·h 1.67MJ Example 5 99.6% 0.08 1.12 kWh 1.70MJ Comparative Example 1 91.2% 0.41 1.93 kWh 5.8MJ

[0068] A comparison of the experimental data in Table 1 reveals that the ferric chloride preparation process of this invention has high efficiency. High conversion rate and low cost and energy consumption.

[0069] A comparison of the experimental data from Examples 1-5 and Comparative Example 1 in Table 1 reveals that Examples 1-5... The high conversion rate and low chlorine consumption, total power consumption, and steam heat consumption indicate that the use of low ambient temperature fixed-bed biochemical oxidation and in-situ electrochemical chlorine cycle can reduce heat consumption. At the same time, due to the use of in-situ electrochemical chlorine cycle, chlorine forms a closed loop, and chlorine is generated and consumed in-situ at the anode, thus reducing the cost of chemicals.

[0070] Test Example 2

[0071] Test methods: Chlorine concentration was measured by gas bag absorption-spectroscopy; hydrogen chloride mist concentration was measured by acid titration; and free acid concentration, total copper ion and nickel ion concentrations were measured according to GB / T4482-2018. Results are shown in Table 2.

[0072] Table 2. Statistical analysis of test results using the air bag absorption-spectroscopy method.

[0073] chlorine concentration Hydrochloric acid mist concentration Total concentration of copper and nickel ions Free acid concentration Example 1 2.4 mg·m⁻³ 6.9 mg·m⁻³ 19.5ppm 0.70wt% Example 2 2.1 mg·m⁻³ 6.7 mg·m⁻³ 19.8ppm 0.72wt% Example 3 2.2 mg·m⁻³ 6.6 mg·m⁻³ 20.0ppm 0.73wt% Example 4 2.3 mg·m⁻³ 6.5 mg·m⁻³ 19.7ppm 0.70wt% Example 5 2.0 mg·m⁻³ 6.8 mg·m⁻³ 19.6ppm 0.71wt% Comparative Example 1 18.3 mg·m⁻³ 27.2 mg·m⁻³ 136.8ppm 1.32wt%

[0074] A comparison of the experimental data in Table 2 reveals that the ferric chloride preparation process of this invention is characterized by being green and having high purity.

[0075] A comparison of the experimental data of Examples 1-5 and Comparative Example 1 in Table 2 shows that the chlorine concentration and hydrogen chloride acid mist concentration of Examples 1-5 are low, indicating that high-temperature slag and acid mist injection were not used, resulting in a lower mass concentration of chlorine and hydrogen chloride emissions compared to traditional processes, meeting the latest atmospheric emission control requirements and making the entire preparation process green and safe.

[0076] A comparison of the experimental data from Examples 1-5 and Comparative Example 1 reveals that the total concentrations of copper and nickel ions and the concentration of free acid in Examples 1-5 are low. This indicates that by first filtering and adjusting the pH of the steel pickling waste liquid before reacting with iron powder, heavy metal ions in the waste liquid can be removed through the reaction with iron powder. At the same time, the concentration of ferrous ions in the waste liquid is further increased, and the total concentrations of copper and nickel ions are reduced without introducing other impurities.

[0077] Test Example 3

[0078] Test method: The ferric chloride prepared in each example and comparative example was left to stand for 7 days, and crystallization was observed. The results are shown in Table 3.

[0079] Table 3 Crystallization Statistics

[0080] Whether it crystallizes Example 1 no Example 2 no Example 3 no Example 4 no Example 5 no Comparative Example 1 yes

[0081] A comparison of the experimental data in Table 3 reveals that the ferric chloride preparation process of this invention is characterized by its resistance to crystallization and hydrolysis.

[0082] A comparison of the experimental data of Examples 1-5 and Comparative Example 1 in Table 3 shows that no crystallization occurred in Examples 1-5, indicating that the combination of ferric chloride and stabilizer can make the prepared ferric chloride stable and less prone to crystallization and hydrolysis.

[0083] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A process for preparing ferric chloride, characterized in that, The process for preparing ferric chloride involves filtering and adjusting the pH of the steel pickling waste liquid, reacting it with iron powder, then using fixed-bed biochemical oxidation, followed by in-situ electrochemical chlorine circulation, and finally concentrating, removing impurities, and compounding it with a stabilizer to obtain liquid ferric chloride. The stabilizers are phosphorous acid, hydroxyethylidene diphosphonic acid, and imidazoline derivatives.

2. The process for preparing ferric chloride according to claim 1, characterized in that, The preparation process of ferric chloride mainly includes the following steps: (1) Mix steel pickling waste liquid with 60 mesh quartz sand at a mass ratio of 8~12:1, sonicate for 10~14 min, filter, adjust the pH to 1.8~2 with calcium hydroxide aqueous solution to obtain steel pickling waste liquid treatment liquid pretreatment liquid, mix steel pickling waste liquid treatment liquid pretreatment liquid with iron powder at a mass ratio of 30~32:1, stir at 38~42℃ and 200~300r / min for 1.5~1.7h, filter, take the filtrate to obtain steel pickling waste liquid treatment liquid; (2) The steel pickling waste liquid is treated by fixed-bed biochemical oxidation. The reactor material is a steel cylinder lined with polyvinylidene fluoride, the packing material is volcanic rock ceramsite with a diameter of 5~15mm, the microorganism is a single strain with the preservation number CGMCC No.XX"AF-2025", the reaction temperature is 30~35℃, the residence time is 3.8~4.2h, and the biochemical effluent is obtained. (3) Using the biochemical effluent as the electrolyte, an in-situ electrochemical chlorine cycle was carried out at a reaction temperature of 35~45°C to obtain a chlorine cycle treatment solution; (4) Concentrate the chlorine recycling solution and then remove impurities to obtain a concentrated solution; (5) The concentrated solution, phosphorous acid, hydroxyethylidene diphosphonic acid and imidazoline derivative are mixed evenly in a mass ratio of 98.7~99.4:0.5~1.0:0.05~0.2:0.05~0.1 to obtain liquid ferric chloride.

3. The process for preparing ferric chloride according to claim 2, characterized in that, The main components and concentrations of the steel pickling waste liquid mentioned in step (1) are as follows: ferrous chloride Free hydrogen chloride 6~12wt%, copper ions 0~200ppm, nickel ions 0~120ppm.

4. The process for preparing ferric chloride according to claim 2, characterized in that, The mass fraction of the calcium hydroxide aqueous solution in step (1) is 9% to 11%.

5. The process for preparing ferric chloride according to claim 2, characterized in that, The in-situ electrochemical chlorine cycle described in step (3) uses a 316L stainless steel plate as the cathode and a 316L stainless steel plate as the anode. electrode.

6. The process for preparing ferric chloride according to claim 2, characterized in that, The current density of the in-situ electrochemical chlorine cycle in step (3) is .

7. The process for preparing ferric chloride according to claim 2, characterized in that, The specific operation of concentration in step (4) is to dry at 88~92℃ and 34~36kPa for 1~1.2h.

8. The process for preparing ferric chloride according to claim 2, characterized in that, The impurity removal in step (4) is carried out using an activated carbon tower.

9. An application of ferric chloride, characterized in that, The application of ferric chloride refers to the application of ferric chloride prepared by the ferric chloride preparation process described in any one of claims 1 to 8 in drinking water treatment, urban sewage purification, industrial wastewater purification, and other fields.