A steel slag conversion process for total chromium removal

Abstract

The application discloses a steel slag conversion method for total chromium removal, and belongs to the field of functional materials. The steel slag is subjected to water bath treatment in an alcohol-water mixed solvent by using an organic carboxylic acid, then the obtained powder is dispersed in water, the suspension is adjusted to an alkaline pH of 8-11, and then a phosphate is added to perform a heating reaction in a water bath. In the application, by controlling the reaction conditions, the elements such as Fe and Ca rich in the steel slag can be effectively utilized, the iron ions in the steel slag are converted into carboxylic acid complexes, and the calcium ions are converted into calcium hydroxyphosphates, so that the illumination reduction of Cr(Ⅵ) and the adsorption and fixation of Cr(III) products are realized respectively, and the purpose of effectively removing chromium is achieved. Therefore, the application not only realizes the effective utilization of the steel slag solid waste, but also realizes the removal of chromium pollutants in sewage, and has good economic value and environmental effect.

Description

TECHNICAL FIELD

[0001] The present application relates to a steel slag conversion method for total chromium removal, and belongs to the field of functional materials. BACKGROUND

[0002] Wastewater used in the metallurgical, electroplating, leather and other industries contains a large amount of Cr(Ⅵ) ions, which is harmful to humans. Cr(Ⅵ) has significant toxicity, and frequent contact of human body with Cr(Ⅵ) can cause cancer of body tissues and organs, and even death when the concentration of Cr(Ⅵ) is too high. It is essential to eliminate Cr(Ⅵ) in wastewater, but the reduced Cr(III) product, especially in the natural environment, will be re-oxidized to Cr(Ⅵ) by manganese oxides and other secondary oxidants if not removed in time, thereby continuously endangering the environment. Therefore, after Cr(VI) is reduced to Cr(III), continuing to adsorb and fix Cr(III) to achieve total chromium removal is an effective way to solve the above problems. Industrial by-products represented by steel slag are the largest solid waste in terms of discharge, and their resource utilization is one of the current research hotspots. By converting steel slag into efficient chromium removal materials, efficient utilization of solid waste can be achieved.

[0003] In the present application, by controlling the reaction conditions, the elements such as Fe and Ca rich in steel slag can be effectively utilized, the iron ions in steel slag are converted into carboxylic acid complexes, and the calcium ions are converted into hydroxyapatite, thereby realizing the photo-reduction of Cr(Ⅵ) and the adsorption and fixation of Cr(III) product, respectively, and achieving the purpose of effective chromium removal. SUMMARY

[0004] The purpose of the present application is to provide a steel slag conversion method for total chromium removal, which effectively utilizes steel slag solid waste, and the method is simple, conducive to batch preparation, can greatly reduce the cost, improve the efficiency, and has great practical significance.

[0005] The present application needs to solve the functional conversion of steel slag by simple reaction parameter control in order to reduce the cost and realize batch synthesis.

[0006] The purpose of the present application is achieved by the following technical solutions:

[0007] The present application provides a steel slag conversion method for total chromium removal, characterized in that it comprises the following steps:

[0008] (1) First, the steel slag is ground to 30-200 mesh, sieved, and the obtained powder is treated with organic carboxylic acid in an alcohol-water mixed solvent in a water bath, the water bath treatment temperature is 50-90℃, and the water bath treatment time is 1-10 hours, to obtain carboxyl modified steel slag powder, wherein the carboxyl groups are complexed with the surface Fe ions;

[0009] (2) the powder obtained in step (1) is dispersed in water, the suspension is adjusted to be alkaline (pH = 8-11), and then a phosphate is added to react in a water bath, the temperature of the water bath reaction is 60-90℃, and the time of the water bath reaction is 5-10 hours, so as to obtain the carboxyl-modified steel slag powder loaded with hydroxyapatite.

[0010] In step (1), the steel slag is a solid waste material rich in iron and calcium; the particle size of the steel slag powder is 60 mesh; the amount of the steel slag powder, organic carboxylic acid, alcohol and water is (2-5) g: 20-40 mL: (2-8) mL: (20-40) mL.

[0011] In step (1), the steel slag is a solid waste material rich in iron and calcium; the particle size of the steel slag powder is 60 mesh; the amount of the steel slag powder, organic carboxylic acid, alcohol and water is (2-5) g: 20-40 mL: (2-8) mL: (20-40) mL.

[0012] In step (2), the suspension is adjusted to pH = 8-11 by adding ammonia.

[0013] The phosphate is diammonium hydrogen phosphate, ammonium dihydrogen phosphate, sodium dihydrogen phosphate, disodium hydrogen phosphate, potassium dihydrogen phosphate, or disodium hydrogen phosphate, preferably diammonium hydrogen phosphate; the mass ratio of the organic carboxylic acid-modified steel slag to the phosphate is 7-10:1, preferably 9-10:1.

[0014] The prepared carboxyl-modified steel slag powder loaded with hydroxyapatite can realize reduction of Cr(VI) and adsorption and fixation of Cr(III) products under visible light irradiation, that is, it can realize reduction of Cr(VI) to Cr(III) under visible light irradiation, and at the same time, the obtained Cr(III) products are adsorbed and fixed, so that the total chromium in the solution is reduced; preferably, the concentration of the modified steel slag powder in the Cr(VI)-containing solution is 0.4-0.6 mg / L; the concentration of Cr(VI) in the solution is 2-20 mg / L, preferably 5-15 mg / L; after the reaction, the concentration of Cr(VI) in the solution is detected by the national standard "Determination of Hexavalent Chromium in Water - Diphenylcarbazide Spectrophotometric Method" (GB 7467-87), and the concentration of Cr(VI) is ≤0.1 mg / L; the total chromium Cr concentration is ≤1 mg / L, which is detected by atomic emission spectroscopy (ICP-AES).

[0015] The preparation method of the present application can effectively convert Fe and Ca elements in the steel slag into chromium removal materials, can realize removal of total chromium in wastewater, has good repeatability, simple operation, low cost, and effectively realizes recycling of steel slag solid waste. BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 1 : ultraviolet-visible absorption spectrum of steel slag, step (1) organic carboxylic acid-modified steel slag and step (2) phosphate-modified steel slag;

[0017] Figure 2 Figure 3 is a diagram showing the change in the UV-visible absorption spectrum of Cr(Ⅵ) in an aqueous solution under the action of the prepared modified steel slag under visible light irradiation. DETAILED DESCRIPTION

[0018] The application will be further described in conjunction with the following examples, but the application is not limited to the following examples.

[0019] Example 1

[0020] (1) First, the steel slag is ground to 30 mesh, sieved, and the obtained powder is treated in a water bath with formic acid in a mixed solvent of ethanol and water, the water bath treatment temperature is 50°C, and the water bath treatment time is 1 hour, to obtain carboxyl-modified steel slag powder, wherein the carboxyl groups are complexed with the surface Fe ions.

[0021] (2) The carboxyl-modified steel slag powder obtained in step (1) is dispersed in water, the suspension is adjusted to be alkaline (pH = 8), and then ammonium dihydrogen phosphate is added in a mass ratio of 7:1 of the carboxyl-modified steel slag to ammonium dihydrogen phosphate, and heated in a water bath to react, the water bath reaction temperature is 60°C, and the water bath reaction time is 5 hours, to obtain carboxyl-modified steel slag powder loaded with hydroxyapatite.

[0022] In step (1), the steel slag is a solid waste material rich in iron and calcium; the particle size of the steel slag powder is 30 mesh; the amount of steel slag powder: organic carboxylic acid: alcohol and water is 2g:20mL:2mL:20mL.

[0023] The prepared modified steel slag can realize the reduction of Cr(VI) and the adsorption and fixation of Cr(III) products under visible light irradiation, wherein preferably, the concentration of the modified steel slag powder in the Cr(VI)-containing solution is 0.4mg / L; the concentration of Cr(VI) in the solution is 2mg / L; after the reaction, the concentration of Cr(VI) in the solution is detected by the national standard "Determination of Cr(VI) in Water by Diphenylcarbazide Spectrophotometry" (GB 7467-87), the concentration of Cr(VI) is 0.01mg / L, and the total chromium Cr concentration is 0.1mg / L detected by atomic emission spectroscopy (ICP-AES).

[0024] Example 2

[0025] (1) First, the steel slag is ground to 200 mesh, sieved, and the obtained powder is treated in a water bath with acetic acid in a mixed solvent of ethylene glycol and water, the water bath treatment temperature is 90°C, and the water bath treatment time is 10 hours, to obtain carboxyl-modified steel slag powder, wherein the carboxyl groups are complexed with the surface Fe ions.

[0026] (2) The organic carboxylic acid modified steel slag powder obtained in step (1) is dispersed in water, the suspension is adjusted to be alkaline (pH = 11), and then disodium hydrogen phosphate is added in a mass ratio of 10:1 of the organic carboxylic acid modified steel slag to the disodium hydrogen phosphate. The reaction is heated in a water bath, the temperature of the water bath reaction is 70°C, and the time of the water bath reaction is 7 hours, so as to obtain the carboxylic acid modified steel slag powder loaded with hydroxyapatite.

[0027] In step (1), the steel slag is a solid waste material rich in iron and calcium; the particle size of the steel slag powder is 200 mesh; the amount of the steel slag powder, the organic carboxylic acid, the alcohol and the water is in a ratio of 5g:40mL:8mL:40mL.

[0028] The prepared modified steel slag can realize reduction of Cr(VI) and adsorption and fixation of Cr(III) products under visible light irradiation, wherein preferably, the concentration of the modified steel slag powder in the Cr(VI)-containing solution is 0.6mg / L; the concentration of Cr(VI) in the solution is 20mg / L; after the reaction, the concentration of Cr(VI) in the solution is detected by the national standard “Determination of Cr(VI) in Water-Diphenylcarbazide Spectrophotometric Method” (GB 7467-87), the concentration of Cr(VI) is 0.09mg / L, and the total chromium Cr concentration is 0.7mg / L detected by atomic emission spectroscopy (ICP-AES).

[0029] Example 3

[0030] (1) First, the steel slag is ground to 60 mesh, sieved, and the obtained powder is subjected to water bath treatment with propionic acid in a mixture of glycerol and water, the water bath treatment temperature is 70°C, and the water bath treatment time is 5 hours, so as to obtain carboxylic acid modified steel slag powder, wherein the carboxyl groups are complexed with the surface Fe ions.

[0031] (2) The organic carboxylic acid modified steel slag powder obtained in step (1) is dispersed in water, the suspension is adjusted to be alkaline (pH = 9), and then disodium hydrogen phosphate is added in a mass ratio of 10:1 of the organic carboxylic acid modified steel slag to the disodium hydrogen phosphate. The reaction is heated in a water bath, the temperature of the water bath reaction is 70°C, and the time of the water bath reaction is 7 hours, so as to obtain the carboxylic acid modified steel slag powder loaded with hydroxyapatite.

[0032] In step (1), the steel slag is a solid waste material rich in iron and calcium; the particle size of the steel slag powder is 60 mesh; the amount of the steel slag powder, the organic carboxylic acid, the alcohol and the water is in a ratio of 3g:30mL:5mL:30mL.

[0033] The prepared modified steel slag can achieve Cr(VI) reduction and Cr(III) product adsorption and fixation under visible light irradiation. Preferably, the concentration of modified steel slag powder in Cr(VI) solution is 0.5 mg / L; the Cr(VI) concentration in solution is 10 mg / L; after the reaction, the Cr(VI) concentration in the solution is detected by the national standard "Determination of Hexavalent Chromium in Water by Diphenylcarbazide Spectrophotometric Method" (GB 7467-87), and the Cr(VI) concentration is 0.05 mg / L. The total chromium Cr concentration is detected by atomic emission spectrometry (ICP-AES), and the total chromium Cr concentration is 0.6 mg / L.

[0034] Example 4

[0035] (1) First, steel slag is ground to 100 mesh and sieved. The resulting powder is treated with acetic acid in a mixed solvent of ethanol and water in a water bath at a temperature of 80°C for 9 hours to obtain carboxyl-modified steel slag powder, wherein the carboxyl groups are complexed with Fe ions on the surface.

[0036] (2) Disperse the organic carboxylic acid modified steel slag powder obtained in step (1) in water, adjust the suspension to alkaline (pH=10), and then add dipotassium hydrogen phosphate in a mass ratio of 8:1 for organic carboxylic acid modified steel slag to dipotassium hydrogen phosphate and heat the reaction in a water bath. The temperature of the water bath reaction is 80℃ and the reaction time is 8 hours to obtain carboxyl modified steel slag powder loaded with hydroxyapatite.

[0037] In step (1), steel slag is a solid waste material rich in iron and calcium; the particle size of steel slag powder is 100 mesh; the ratio of steel slag powder, organic carboxylic acid, alcohol and water is 4g:40mL:7mL:30mL.

[0038] The prepared modified steel slag can achieve Cr(VI) reduction and Cr(III) product adsorption and fixation under visible light irradiation. Preferably, the concentration of modified steel slag powder in Cr(VI) solution is 0.6 mg / L; the Cr(VI) concentration in solution is 15 mg / L; after the reaction, the Cr(VI) concentration in the solution is detected by the national standard "Determination of Hexavalent Chromium in Water by Diphenylcarbazide Spectrophotometric Method" (GB 7467-87), and the Cr(VI) concentration is 0.07 mg / L. The total chromium Cr concentration is detected by atomic emission spectrometry (ICP-AES), and the total chromium Cr concentration is 0.7 mg / L.

[0039] Example 5

[0040] (1) First, the steel slag is ground to 150 mesh and sieved. The resulting powder is treated with propionic acid in a mixed solvent of ethanol and water in a water bath at a temperature of 80°C for 9 hours to obtain carboxyl-modified steel slag powder, wherein the carboxyl groups are complexed with Fe ions on the surface.

[0041] (2) The organic carboxylic acid modified steel slag powder obtained in step (1) is dispersed in water, and the suspension is adjusted to be alkaline (pH = 10), and then sodium dihydrogen phosphate is added in a mass ratio of 7.5:1 of the organic carboxylic acid modified steel slag to sodium dihydrogen phosphate, and heated and reacted in a water bath, the temperature of the water bath reaction is 70°C, and the time of the water bath reaction is 9 hours, to obtain a carboxylic acid modified steel slag powder loaded with hydroxyapatite.

[0042] In step (1), the steel slag is a solid waste material rich in iron and calcium; the particle size of the steel slag powder is 150 mesh; the amount of steel slag powder: organic carboxylic acid: alcohol and water is 5g:30mL:7mL:40mL.

[0043] The prepared modified steel slag can realize reduction of Cr(VI) and adsorption and fixation of Cr(III) products under visible light irradiation, wherein preferably, the concentration of the modified steel slag powder in the Cr(VI)-containing solution is 0.5mg / L; the concentration of Cr(VI) in the solution is 10mg / L; after the reaction, the concentration of Cr(VI) in the solution is detected by the national standard "Determination of Cr(VI) in water by diphenylcarbazide spectrophotometry" (GB 7467-87), the concentration of Cr(VI) is 0.06mg / L, and the total chromium Cr concentration is 0.6mg / L detected by atomic emission spectroscopy (ICP-AES).

[0044] Example 6

[0045] (1) First, the steel slag is ground to 180 mesh, sieved, and the obtained powder is treated in a water bath with butyric acid in a mixed solvent of ethanol and water, the water bath treatment temperature is 70°C, and the water bath treatment time is 7 hours, to obtain a carboxylic acid modified steel slag powder, wherein the carboxyl groups are complexed with the surface Fe ions.

[0046] (2) The organic carboxylic acid modified steel slag powder obtained in step (1) is dispersed in water, and the suspension is adjusted to be alkaline (pH = 10), and then potassium dihydrogen phosphate is added in a mass ratio of 10:1 of the organic carboxylic acid modified steel slag to potassium dihydrogen phosphate, and heated and reacted in a water bath, the temperature of the water bath reaction is 80°C, and the time of the water bath reaction is 7 hours, to obtain a carboxylic acid modified steel slag powder loaded with hydroxyapatite.

[0047] In step (1), the steel slag is a solid waste material rich in iron and calcium; the particle size of the steel slag powder is 180 mesh; the amount of steel slag powder: organic carboxylic acid: alcohol and water is 5g:40mL:6mL:40mL.

[0048] The prepared modified steel slag can realize reduction of Cr(VI) and adsorption and fixation of Cr(III) product under visible light irradiation, wherein preferably, the concentration of the modified steel slag powder in the Cr(VI)-containing solution is 0.6 mg / L; the concentration of Cr(VI) in the solution is 15 mg / L; the concentration of Cr(VI) in the solution after reaction is detected by the national standard "Determination of Cr(VI) in Water-Diphenylcarbazide Spectrophotometric Method" (GB 7467-87), and the concentration of Cr(VI) is 0.07 mg / L, and the total chromium Cr concentration is 0.6 mg / L detected by atomic emission spectrometry (ICP-AES).

[0049] Example 7

[0050] (1) First, the steel slag is ground to 60 mesh, sieved, and the obtained powder is treated in a water bath with valeric acid in a mixed solvent of ethanol and water, the water bath treatment temperature is 80°C, and the water bath treatment time is 8 hours, to obtain carboxyl-modified steel slag powder, wherein the carboxyl groups are complexed with the surface Fe ions.

[0051] (2) The organic carboxylic acid-modified steel slag powder obtained in step (1) is dispersed in water, the suspension is adjusted to be alkaline (pH=10), and then ammonium hydrogen phosphate is added in a mass ratio of 8.5:1 of the organic carboxylic acid-modified steel slag to ammonium hydrogen phosphate, and heated in a water bath for reaction, the water bath reaction temperature is 70°C, and the water bath reaction time is 5 hours, to obtain carboxyl-modified steel slag powder loaded with hydroxyapatite.

[0052] In step (1), the steel slag is a solid waste material rich in iron and calcium; the particle size of the steel slag powder is 60 mesh; the amount of steel slag powder: organic carboxylic acid: alcohol and water is 3g:40mL:5mL:30mL.

[0053] The prepared modified steel slag can realize reduction of Cr(VI) and adsorption and fixation of Cr(III) product under visible light irradiation, wherein preferably, the concentration of the modified steel slag powder in the Cr(VI)-containing solution is 0.6 mg / L; the concentration of Cr(VI) in the solution is 15 mg / L; the concentration of Cr(VI) in the solution after reaction is detected by the national standard "Determination of Cr(VI) in Water-Diphenylcarbazide Spectrophotometric Method" (GB 7467-87), and the concentration of Cr(VI) is 0.07 mg / L, and the total chromium Cr concentration is 0.6 mg / L detected by atomic emission spectrometry (ICP-AES).

[0054] The above only describes the preferred embodiments of the present application and is not intended to limit the present application, and any modifications, equivalent replacements and improvements made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A method for steel slag conversion for total chromium removal, characterized in that, Includes the following steps: (1) First, steel slag is ground to 30-200 mesh and sieved. The resulting powder is treated with organic carboxylic acid in an alcohol-water mixed solvent in a water bath. The water bath temperature is 50-90℃ and the water bath time is 1-10 hours to obtain carboxyl-modified steel slag powder, wherein the carboxyl group is complexed with Fe ions on the surface. (2) Disperse the powder obtained in step (1) in water, adjust the suspension to alkaline pH = 8-11, and then add phosphate and heat the reaction in a water bath. The temperature of the water bath reaction is 60-90℃ and the reaction time is 5-10 hours to obtain carboxyl-modified steel slag powder loaded with hydroxyapatite.

2. The method according to claim 1, characterized in that, In step (1), the steel slag is ground to 60 mesh.

3. The method according to claim 1, characterized in that, In step (1), the ratio of steel slag powder, organic carboxylic acid, alcohol and water is 2-5g : 20-40 mL : 2-8 mL : 20-40 mL.

4. The method according to claim 1, characterized in that, Steel slag is a solid waste material rich in iron and calcium; alcohol is selected from ethanol, ethylene glycol or glycerol.

5. The method according to claim 1, characterized in that, Organic carboxylic acids are selected from formic acid, acetic acid, propionic acid, butyric acid, or valeric acid.

6. The method according to claim 1, characterized in that, The phosphate is diammonium hydrogen phosphate, ammonium dihydrogen phosphate, sodium dihydrogen phosphate, disodium hydrogen phosphate, potassium dihydrogen phosphate, or dipotassium hydrogen phosphate. The mass ratio of the organic carboxylic acid modified steel slag to the phosphate is 7-10:

1.

7. The method according to claim 1, characterized in that, The mass ratio of the organic carboxylic acid-modified steel slag to phosphate used is 9-10:

1.

8. The method according to claim 1, characterized in that, The suspension was adjusted to pH 8-11 by adding ammonia.

9. Modified steel slag powder prepared according to any one of claims 1-8.

10. The modified steel slag powder prepared according to any one of claims 1-8 can achieve Cr(VI) reduction and Cr(III) product adsorption and fixation under visible light irradiation.

11. The application according to claim 10 is used to reduce Cr(VI) to Cr(III) under visible light irradiation, while simultaneously adsorbing and fixing the resulting Cr(III) product, thereby reducing the total chromium in the solution; the concentration of the modified steel slag powder in the Cr(VI)-containing solution is 0.4-0.6 mg / L; the concentration of Cr(VI) in the solution is 2-20 mg / L; the concentration of Cr(VI) in the solution after the reaction is detected by the national standard "Determination of Hexavalent Chromium in Water by Diphenylcarbazide Spectrophotometric Method" (GB 7467-87), and the Cr(VI) concentration is ≤0.1 mg / L; the total chromium concentration is ≤1 mg / L as detected by atomic emission spectroscopy.

12. In the application according to claim 11, the concentration of Cr(VI) in the solution is 5-15 mg / L.

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