A method for sulfur-modification of iron-containing solid waste for chromium and thallium fixation

Abstract

A method for sulfidation modification of iron-containing solid waste for chromium and thallium fixation belongs to the field of functional materials. Using iron-rich industrial solid waste as raw material, after grinding and sieving, it is activated in a water bath using organic carboxylic acids. Through a complexation reaction, the inert iron structure within the solid waste is activated, yielding a carboxylic acid-activated solid waste intermediate. This intermediate is then mixed with a sulfiding agent and subjected to a sulfidation reaction in a high-sodium environment to obtain a NaFeS2·2H2O compound, which is uniformly loaded onto the surface of the iron-containing solid waste. This material can achieve synergistic fixation of Cr(VI) reduction and in-situ adsorption of Cr(III) within a pH range of 2.5-11, expanding the pH applicability range of simple sulfur-iron reducing agents. It can also achieve the adsorption and fixation of typical toxic metal ions Tl⁺ in the environment. This invention achieves functionalization of the surface of iron-containing solid waste through simple sulfidation reaction control. The preparation process is simple, low-cost, and easy to synthesize in batches, thus realizing the resource reuse of solid waste.

Description

Technical Field

[0001] This invention relates to a method for sulfurization modification of iron-containing solid waste for chromium and thallium fixation, belonging to the field of functional materials. Background Technology

[0002] The iron and steel smelting industry generates a large amount of solid waste annually, which contains various heavy metal ions, with chromium (Cr(VI)) and thallium (Tl) being the main pollutants. If these metal ions are not purified and immobilized, they will be released during landfilling or resource utilization, causing secondary pollution to the environment and endangering human health. To address this issue, a waste-to-waste approach can be adopted. Using iron-rich solid waste as raw material, surface activation to enrich active iron, and subsequent sulfidation operations, the surface of iron-containing solid waste can be modified by sulfidation, thereby immobilizing coexisting or externally present chromium and thallium metal ions.

[0003] In this invention, by controlling the reaction conditions, the Fe element in iron-containing solid waste can be effectively utilized to convert the inert structural iron in the solid waste into active iron-containing carboxylates, which are then sulfided to generate ferric sulfide compounds. This achieves the reduction of Cr(VI) and the adsorption and fixation of Cr(III) products, as well as the reduction of Tl. + The exchange of ions effectively passivates and fixes harmful metal ions such as chromium and thallium. Summary of the Invention

[0004] The purpose of this invention is to provide a sulfurization modification method for iron-containing solid waste for chromium and thallium fixation. This method effectively utilizes iron-containing solid waste, is simple, facilitates batch preparation, can greatly reduce costs, improve efficiency, and has good potential for widespread application.

[0005] The present invention aims to achieve the sulfidation conversion of iron-containing solid waste through simple control of reaction conditions, thereby enabling mass synthesis.

[0006] The objective of this invention is achieved through the following technical solution:

[0007] This invention provides a method for sulfidation modification of iron-containing solid waste, characterized by comprising the following steps:

[0008] (1) First, the iron-containing solid waste is ground to 30-300 mesh. The resulting powder is treated with an organic acid aqueous solution in a water bath. The mixture is stirred and the treatment temperature is from room temperature to 50 ℃. The water bath treatment time is 1-6 hours. Through this step, active carboxylic acid iron salts can be enriched on the surface of the solid waste. Then, the solid waste powder containing active carboxylic acid iron salts is obtained by filtration and drying.

[0009] (2) Add an aqueous solution of sulfiding agent to the solid waste powder containing active iron carboxylate obtained in step (1), stir evenly to form a slurry, and then filter and dry to obtain solid waste powder containing iron sulfur compound.

[0010] In step (1), the iron-containing solid waste is an industrial solid waste rich in iron. Steel slag produced by the steel industry is preferred as raw material, and its iron content (mass fraction) is ≥ 1%.

[0011] The organic acid is one or more of formic acid, acetic acid, propionic acid, oxalic acid, citric acid, malic acid, and salicylic acid, with acetic acid being preferred. The concentration of the organic acid solution is greater than or equal to 0.05 mol / L, generally between 0.05 mol / L and 10 mol / L. The ratio of the amount of iron-containing solid waste powder to the amount of organic carboxylic acid solution is 30-50 mL of organic carboxylic acid solution for every 3-6 g of iron-containing solid waste powder, preferably 30 mL of organic carboxylic acid solution for every 6 g of iron-containing solid waste powder.

[0012] The sulfiding agent is one or more of sodium sulfide, potassium sulfide, sodium thiosulfate, and thioacetamide, preferably one or more of sodium sulfide and potassium sulfide, and the ferrous sulfate compound is NaFeS2·2H2O or / and KFeS2; the mass ratio of solid waste powder containing active ferric carboxylate to sulfiding agent is 8-12:1, preferably 10-11:1, and the stirring rate is 100-300 r / min.

[0013] Application of the solid waste powder containing ferrous sulfate compounds obtained by this invention, for use in solutions containing Cr(VI) and / or Tl. + Fixed removal. Contains Cr(VI) and / or Tl. + The aqueous solution can also be used for Cr(VI) and / or Tl-containing substances generated in the steel smelting industry. + The aqueous solution achieves the same effect as other companies in the industry: treating waste with waste.

[0014] Further for Cr(VI) fixation and removal, solid waste powder containing ferrous sulfate compounds is mixed and contacted with a Cr(VI)-containing solution. Within a pH range of 2.5-11, preferably 3-6, Cr(VI) can be reduced to Cr(III) and in-situ adsorption and fixation can be achieved. Preferably, the concentration of the solid waste powder containing ferrous sulfate compounds in the Cr(VI)-containing solution is 0.3-0.9 mg / L. The initial concentration of Cr(VI) in the Cr(VI)-containing solution is ≤ 20 mg / L, preferably 2-5 mg / L. After the reaction, the Cr(VI) content in the solution is detected using the national standard "Determination of Hexavalent Chromium in Water - Diphenylcarbazide Spectrophotometric Method" (GB 7467-87). The results show that the Cr(VI) concentration does not exceed 0.01 mg / L, and the total chromium concentration is detected by atomic emission spectrometry (ICP-AES), with a detected value not exceeding 0.5 mg / L.

[0015] Further Tl +Fixed removal: Solid waste powder containing pyrite compounds is reacted with Tl... + Solution mixing and contact, within a pH range of 3-11, preferably pH 6-11, can achieve Tl. + Adsorption and fixation, wherein the preferred method is to adsorb and fix solid waste powder containing sulfide compounds in a Tl-containing medium. + The dosage concentration in the solution is 0.5-2.5 mg / L; wherein the Tl content is... + In solution, Tl + The initial concentration range is ≤ 200 μg / L, preferably 5-20 μg / L; after the reaction is complete, the Tl in the solution... + The content of thallium was detected using the national standard "Determination of Thallium in Water - Graphite Furnace Atomic Absorption Spectrophotometry" (HJ 748-2015). The results showed that Tl... + The concentration should not exceed 0.1 μg / L.

[0016] The beneficial effects of this invention are: the preparation method of this invention can effectively utilize Fe in iron-containing solid waste to transform it into a sulfur-iron compound with both chemical reduction and ion exchange capabilities, and can achieve chromium and thallium fixation. It has good repeatability, is simple to operate, and has low cost, thus effectively realizing the reuse of iron-containing solid waste. Attached Figure Description

[0017] Figure 1 XRD patterns of different powders. Detailed Implementation

[0018] The present invention will be further described below with reference to the embodiments, but the present invention is not limited to the following embodiments.

[0019] Example 1

[0020] (1) First, the iron-containing solid waste is ground to 30 mesh. The resulting powder is treated with an organic acid aqueous solution in a water bath. The mixture is stirred and the treatment temperature is room temperature. The water bath treatment time is 1 hour. Through this step, the inert structural iron in the solid waste can be converted into active carboxylic acid iron salt enriched on the surface.

[0021] (2) Add sulfide aqueous solution to the powder obtained in step (1) and stir evenly to form a slurry to obtain iron-containing solid waste powder modified with sulfide-iron compound.

[0022] In step (1), the iron-containing solid waste is an industrial solid waste rich in iron. Steel slag produced by the steel industry is preferred as raw material, and its iron content (mass fraction) is 1%.

[0023] The organic acid is acetic acid with a concentration of 0.05 mol / L, and the ratio of iron-containing solid waste powder to acetic acid solution is 3g : 30 mL.

[0024] The sulfiding agent is sodium sulfide, the sulfidation product is NaFeS2·2H2O, the mass ratio of solid waste containing active carboxylic acid iron salt to sodium sulfide is 8:1, and the stirring rate is 100 r / min.

[0025] The prepared sulfide-modified iron-containing solid waste powder was contacted with a Cr(VI)-containing solution. At pH 5, Cr(VI) was reduced to Cr(III) and in-situ adsorbed and fixed. The concentration of the sulfide-modified iron-containing solid waste powder in the Cr(VI)-containing solution was 0.3 mg / L. The initial concentration of Cr(VI) in the Cr(VI)-containing solution was in the range of 20 mg / L. After the reaction, the Cr(VI) content in the solution was detected using the national standard "Determination of Hexavalent Chromium in Water - Diphenylcarbazide Spectrophotometric Method" (GB 7467-87). The results showed that the Cr(VI) concentration was 0.01 mg / L, and the total chromium concentration was detected by atomic emission spectrometry (ICP-AES), with a detected value of 0.5 mg / L.

[0026] Example 2

[0027] (1) First, the iron-containing solid waste is ground to 30 mesh. The resulting powder is treated with an organic acid aqueous solution in a water bath. The mixture is stirred and the treatment temperature is 50 °C. The water bath treatment time is 1 hour. This step can convert the inert structural iron in the solid waste into active carboxylic acid iron salts enriched on the surface.

[0028] (2) Add sulfide aqueous solution to the powder obtained in step (1) and stir evenly to form a slurry to obtain iron-containing solid waste powder modified with sulfide-iron compound.

[0029] In step (1), the iron-containing solid waste is an industrial solid waste rich in iron. Steel slag produced by the steel industry is preferred as raw material, and its iron content (mass fraction) is 1%.

[0030] The organic acid is acetic acid with a concentration of 0.05 mol / L, and the ratio of iron-containing solid waste powder to acetic acid solution is 6g : 30 mL.

[0031] The sulfiding agent is sodium sulfide, the sulfidation product is NaFeS2·2H2O, the mass ratio of solid waste containing active carboxylic acid iron salt to sodium sulfide is 12:1, and the stirring rate is 100 r / min.

[0032] The prepared sulfide-modified iron-containing solid waste powder and Tl-containing + Solution contact can achieve Tl at pH=6. + Adsorption and fixation, with NaFeS2·2H2O modified iron-containing solid waste powder being the preferred method in the presence of Tl. +The dosage concentration in the solution is 0.6 mg / L. The solution containing Tl... + In solution, Tl + The initial concentration range was 200 μg / L; after the reaction was completed, the Tl concentration in the solution was... + The content of thallium was detected using the national standard "Determination of Thallium in Water - Graphite Furnace Atomic Absorption Spectrophotometry" (HJ 748-2015). The results showed that Tl... + Concentration: 0.1 μg / L.

[0033] Example 3

[0034] (1) First, the iron-containing solid waste is ground to 300 mesh. The resulting powder is treated with an organic acid aqueous solution in a water bath. The mixture is stirred and the treatment temperature is room temperature. The water bath treatment time is 6 hours. Through this step, the inert structural iron in the solid waste can be converted into active carboxylic acid iron salt enriched on the surface.

[0035] (2) Add sulfide aqueous solution to the powder obtained in step (1) and stir evenly to form a slurry to obtain iron-containing solid waste powder modified with sulfide-iron compound.

[0036] In step (1), the iron-containing solid waste is an industrial solid waste rich in iron. Steel slag produced by the steel industry is preferred as raw material, and its iron content (mass fraction) is 10%.

[0037] The organic acid is acetic acid with a concentration of 0.1 mol / L, and the ratio of iron-containing solid waste powder to acetic acid solution is 6g : 30 mL.

[0038] The sulfiding agent is sodium sulfide, the sulfidation product is NaFeS2·2H2O, the mass ratio of solid waste containing active carboxylic acid iron salt to sodium sulfide is 12:1, and the stirring rate is 300 r / min.

[0039] The prepared sulfide-modified iron-containing solid waste powder was contacted with a Cr(VI)-containing solution. At pH 11, Cr(VI) was reduced to Cr(III) and in-situ adsorbed and fixed. The concentration of the NaFeS2·2H2O-modified iron-containing solid waste powder in the Cr(VI)-containing solution was 0.9 mg / L. The initial concentration of Cr(VI) in the Cr(VI)-containing solution was in the range of 10 mg / L. After the reaction, the Cr(VI) content in the solution was detected using the national standard "Determination of Hexavalent Chromium in Water - Diphenylcarbazide Spectrophotometric Method" (GB 7467-87). The results showed that the Cr(VI) concentration was 0.01 mg / L, and the total chromium concentration was detected by atomic emission spectrometry (ICP-AES), with a detected value of 0.4 mg / L.

[0040] Example 4

[0041] (1) First, the iron-containing solid waste is ground to 200 mesh. The resulting powder is treated with an organic acid aqueous solution in a water bath. The mixture is stirred and the treatment temperature is room temperature. The water bath treatment time is 3 hours. Through this step, the inert structural iron in the solid waste can be converted into active carboxylic acid iron salt enriched on the surface.

[0042] (2) Add sulfide aqueous solution to the powder obtained in step (1) and stir evenly to form a slurry to obtain iron-containing solid waste powder modified with sulfide-iron compound.

[0043] In step (1), the iron-containing solid waste is an industrial solid waste rich in iron. Steel slag produced by the steel industry is preferred as raw material, and its iron content (mass fraction) is 15%.

[0044] The organic acid is acetic acid with a concentration of 0.1 mol / L, and the ratio of iron-containing solid waste powder to acetic acid solution is 5g : 30 mL.

[0045] The sulfiding agent is sodium sulfide, the sulfidation product is NaFeS2·2H2O, the mass ratio of solid waste containing active carboxylic acid iron salt to sodium sulfide is 10:1, and the stirring rate is 200 r / min.

[0046] The prepared sulfide-modified iron-containing solid waste powder and Tl-containing + Solution contact can achieve Tl at pH=11. + Adsorption and fixation, with sulfide-modified iron-containing solid waste powder being the preferred method, in the presence of Tl... + The dosage concentration in the solution is 2.5 mg / L. The solution containing Tl... + In solution, Tl + The initial concentration range was 20 μg / L; after the reaction was completed, the Tl concentration in the solution was... + The content of thallium was detected using the national standard "Determination of Thallium in Water - Graphite Furnace Atomic Absorption Spectrophotometry" (HJ 748-2015). The results showed that Tl... + Concentration: 0.05 μg / L.

[0047] Example 5

[0048] (1) First, the iron-containing solid waste is ground to 200 mesh. The resulting powder is treated with an organic acid aqueous solution in a water bath. The mixture is stirred and the treatment temperature is room temperature. The water bath treatment time is 2 hours. Through this step, the inert structural iron in the solid waste can be converted into active carboxylic acid iron salt enriched on the surface.

[0049] (2) Add sulfide aqueous solution to the powder obtained in step (1) and stir evenly to form a slurry to obtain iron-containing solid waste powder modified with sulfide-iron compound.

[0050] In step (1), the iron-containing solid waste is an industrial solid waste rich in iron. Steel slag produced by the steel industry is preferred as raw material, and its iron content (mass fraction) is 9%.

[0051] The organic acid is acetic acid with a concentration of 0.07 mol / L, and the ratio of iron-containing solid waste powder to acetic acid solution is 6g : 40 mL.

[0052] The sulfiding agent is sodium sulfide, the sulfidation product is NaFeS2·2H2O, the mass ratio of solid waste containing active carboxylic acid iron salt to sodium sulfide is 11:1, and the stirring rate is 200 r / min.

[0053] The prepared sulfide-modified iron-containing solid waste powder was contacted with a Cr(VI)-containing solution. At pH 8, Cr(VI) was reduced to Cr(III) and in-situ adsorbed and fixed. The concentration of the sulfide-modified iron-containing solid waste powder in the Cr(VI)-containing solution was 0.5 mg / L. The initial concentration of Cr(VI) in the Cr(VI)-containing solution was in the range of 15 mg / L. After the reaction, the Cr(VI) content in the solution was detected using the national standard "Determination of Hexavalent Chromium in Water - Diphenylcarbazide Spectrophotometric Method" (GB 7467-87). The results showed that the Cr(VI) concentration was 0.01 mg / L, and the total chromium concentration was detected by atomic emission spectrometry (ICP-AES), with a detected value of 0.2 mg / L.

[0054] Example 6

[0055] (1) First, the iron-containing solid waste is ground to 200 mesh. The resulting powder is treated with an organic acid aqueous solution in a water bath. The mixture is stirred and the treatment temperature is room temperature. The water bath treatment time is 4 hours. Through this step, the inert structural iron in the solid waste can be converted into active carboxylic acid iron salt enriched on the surface.

[0056] (2) Add sulfide aqueous solution to the powder obtained in step (1) and stir evenly to form a slurry to obtain iron-containing solid waste powder modified with sulfide-iron compound.

[0057] In step (1), the iron-containing solid waste is an industrial solid waste rich in iron. Steel slag produced by the steel industry is preferred as raw material, and its iron content (mass fraction) is 5%.

[0058] The organic acid is acetic acid with a concentration of 0.08 mol / L, and the ratio of iron-containing solid waste powder to acetic acid solution is 5g : 50 mL.

[0059] The sulfiding agent is sodium sulfide, the sulfidation product is NaFeS2·2H2O, the mass ratio of solid waste containing active carboxylic acid iron salt to sodium sulfide is 10:1, and the stirring rate is 150 r / min.

[0060] The prepared sulfide-modified iron-containing solid waste powder and Tl-containing + Solution contact can achieve Tl at pH=7. + Adsorption and fixation, with sulfide-modified iron-containing solid waste powder being the preferred method, in the presence of Tl... + The dosage concentration in the solution is 2.5 mg / L. The solution containing Tl... + In solution, Tl + The initial concentration range was 50 μg / L; after the reaction was completed, the Tl concentration in the solution was... + The content of thallium was detected using the national standard "Determination of Thallium in Water - Graphite Furnace Atomic Absorption Spectrophotometry" (HJ 748-2015). The results showed that Tl... + Concentration: 0.07 μg / L.

[0061] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for sulfurization modification of iron-containing solid waste, characterized in that, Includes the following steps: (1) First, the iron-containing solid waste is ground to 30-300 mesh. The resulting powder is treated with an organic acid aqueous solution in a water bath. The mixture is stirred and the treatment temperature is from room temperature to 50 ℃. The water bath treatment time is 1-6 hours. Through this step, active carboxylic acid iron salts can be enriched on the surface of the solid waste. Then, the solid waste powder containing active carboxylic acid iron salts is obtained by filtration and drying. (2) Add an aqueous solution of sulfiding agent to the solid waste powder containing active iron carboxylate obtained in step (1), stir evenly to form a slurry, and then filter and dry to obtain solid waste powder containing iron sulfur compound.

2. The method for sulfurization modification of iron-containing solid waste according to claim 1, characterized in that, In step (1), the iron-containing solid waste is an industrial solid waste rich in iron. Steel slag produced by the steel industry is preferred as raw material, and its iron content (mass fraction) is ≥ 1%.

3. The method for sulfurization modification of iron-containing solid waste according to claim 1, characterized in that, The organic acid is one or more of formic acid, acetic acid, propionic acid, oxalic acid, citric acid, malic acid, and salicylic acid, with acetic acid being preferred. The concentration of the organic acid solution is greater than or equal to 0.05 mol / L, generally between 0.05 mol / L and 10 mol / L. The ratio of the amount of iron-containing solid waste powder to the amount of organic carboxylic acid solution is 30-50 mL of organic carboxylic acid solution for every 3-6 g of iron-containing solid waste powder, preferably 30 mL of organic carboxylic acid solution for every 6 g of iron-containing solid waste powder.

4. A method for sulfidation modification of iron-containing solid waste according to claim 1, characterized in that, The sulfiding agent is one or more of sodium sulfide, potassium sulfide, sodium thiosulfate, and thioacetamide, preferably one or more of sodium sulfide and potassium sulfide. The mass ratio of solid waste powder containing active carboxylic acid iron salt to sulfiding agent is 8-12:1, preferably 10-11:1, and the stirring rate is 100-300 r / min.

5. A sulfide-modified iron-containing solid waste prepared according to any one of claims 1-4, characterized in that, It contains iron-sulfur compounds NaFeS2·2H2O or / and KFeS2.

6. The application of a sulfide-modified iron-containing solid waste prepared according to any one of claims 1-4, for use in solutions containing Cr(VI) and / or Tl. + Fixed removal.

7. The application according to claim 6, characterized in that, Contains Cr(VI) and / or Tl + The aqueous solution can also be used for Cr(VI) and / or Tl-containing substances generated in the steel smelting industry. + The aqueous solution achieves the same effect as other companies in the industry: treating waste with waste.

8. The application according to claim 6, characterized in that, For the fixation and removal of Cr(VI), solid waste powder containing ferrous sulfate compounds is mixed and contacted with a Cr(VI)-containing solution. Within a pH range of 2.5-11, preferably 3-6, Cr(VI) can be reduced to Cr(III) and in-situ adsorption and fixation can be achieved. Preferably, the concentration of the solid waste powder containing ferrous sulfate compounds in the Cr(VI)-containing solution is 0.3-0.9 mg / L. The initial concentration of Cr(VI) in the Cr(VI)-containing solution is ≤20 mg / L, preferably 2-5 mg / L. After the reaction, the detection results show that the Cr(VI) concentration does not exceed 0.01 mg / L, and the total chromium concentration is detected by atomic emission spectrometry (ICP-AES), with a detected value not exceeding 0.5 mg / L.

9. The application according to claim 6, characterized in that, Tl + Fixed removal: Solid waste powder containing pyrite compounds is reacted with Tl... + Solution mixing and contact, within a pH range of 3-11, preferably at pH 6-11, can achieve Tl. + Adsorption and fixation, wherein the preferred method is to adsorb and fix solid waste powder containing sulfide compounds in a Tl-containing medium. + The dosage concentration in the solution is 0.5-2.5 mg / L; wherein the Tl content is... + In solution, Tl + The initial concentration range was ≤ 200 μg / L, with 5-20 μg / L being preferred; after the reaction was completed, the detection results showed that Tl + The concentration should not exceed 0.1 μg / L.

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