Method for treating stainless steel pickling wastewater by fused cast aluminum ash

Abstract

The application discloses a method for treating stainless steel pickling wastewater by using fused cast aluminum ash, and belongs to the wastewater treatment field. The method can accelerate the precipitation speed of iron, cadmium, nickel, copper, lead and cadmium precipitates by adding the fused cast aluminum ash into the stainless steel wastewater, and has a remarkable wastewater treatment effect. In combination with the use of a treatment agent, the outer material with a porous structure can increase the COD and ammonia nitrogen removal effect in the wastewater, and the material in the core layer has a longer service life after being wrapped, so that the overall removal rate and removal effect are excellent.

Description

Technical Field

[0001] The invention relates to the field of wastewater treatment, and in particular to a method for treating stainless steel pickling wastewater by using molten aluminum ash. Background Art

[0002] Aluminum profile factories generate large amounts of aluminum ash during the casting and refining process, which is classified as hazardous waste and typically requires payment to qualified environmental protection companies for disposal, which is costly. Stainless steel surface treatment typically utilizes an acid pickling process, and the treatment fluid contains significant amounts of heavy metals such as iron, nickel, and chromium, as well as smaller amounts of lead and cadmium. Conventional technology employs a step-by-step precipitation process based on the properties of the metals: alkaline precipitation for iron, the Fenton process for nickel, and sulfite reduction of chromium to trivalent chromium followed by alkaline precipitation. The treated effluent is then directly discharged, wasting significant amounts of water. The treated wastewater contains heavy metals, which can impact the surrounding environment. Furthermore, the process requires high chemical dosage, is complex, and costs are high, resulting in significant residual sludge and secondary pollution. Summary of the Invention

[0003] Based on this, in order to solve the problems of large dosage of chemicals, complex treatment process, high treatment cost, large amount of residual sludge and secondary pollution in the existing stainless steel pickling process wastewater, the present invention provides a method for treating stainless steel pickling wastewater with molten aluminum ash. The specific technical solution is as follows:

[0004] A method for treating stainless steel pickling wastewater with molten aluminum ash, the method comprising the following steps:

[0005] Add molten aluminum ash to the stainless steel pickling wastewater, stir for 2h~5h, and after the first static treatment, adjust the pH, filter, and discharge the treated wastewater into another treatment tank;

[0006] Adding a treatment agent into the treated wastewater, stirring it and allowing it to stand for a second time, filtering it, and discharging the water;

[0007] The treatment agent is a composite particle, which consists of a core layer and an outer layer wrapping the core layer. The material of the core layer is prepared from modified carbon powder, silicon nitride, starch and shell powder in a mass ratio of (1~3): (1~7): (1~3): 1; the material of the outer layer is a porous material, which is prepared from a mixture of epoxy resin, silicon dioxide and diatomaceous earth in a mass ratio of (0.5~1.2): (1~3): (5~7).

[0008] Furthermore, the addition amount of the molten cast aluminum ash is 18g / 100mL~25g / 100mL.

[0009] Furthermore, the first standing treatment time is 2h~5h.

[0010] Furthermore, the addition amount of the treatment agent is 1g / 100mL~15g / 100mL.

[0011] Furthermore, the stirring process is carried out at a speed of 50 r / min to 120 r / min and for a time of 30 min to 45 min.

[0012] Furthermore, the second standing treatment time is 1 hour to 3 hours.

[0013] Furthermore, the preparation method of the modified carbon powder is as follows: after the corn stalks are crushed, they are treated with supercritical carbon dioxide at a treatment pressure of 5 MPa, a treatment time of 30 min to 40 min, a carbonization temperature of 400°C, and a carbonization time of 1 h to 2 h, and then dispersed in an acetic acid solution, soaked at a temperature of 65°C to 75°C for 1 h to 2 h, filtered, and the filter residue is dispersed in a sodium hydroxide solution, soaked at a temperature of 45°C to 65°C for 1 h to 2 h, filtered, and washed with water to obtain the modified carbon powder.

[0014] Furthermore, the preparation method of the core layer material is: adding modified carbon powder, silicon nitride, starch and shell powder into deionized water, ultrasonically treating for 1 hour to 2 hours, concentrating, drying and granulating to obtain the core layer material.

[0015] Furthermore, the porous material is prepared by adding silicon dioxide and diatomaceous earth to an appropriate amount of deionized water, stirring for 20 minutes to 30 minutes, adding epoxy resin, and continuing to stir for 35 minutes to 45 minutes to obtain the outer layer material.

[0016] Furthermore, the preparation method of the composite particles is: wrapping the outer layer material with the core layer material in a mass ratio of (3-5): (1-3), then calcining at 550-580°C for 1-2 hours, and cooling.

[0017] In the above scheme, stainless steel wastewater is treated by adding aluminum ash. Aluminum ash contains a variety of reducing substances such as sulfites, nitrites, hydrogen sulfide, aluminum nitride, etc. It has a high aluminum content and is alkaline when hydrolyzed. Sulfites can reduce trivalent iron to divalent iron and hexavalent chromium to trivalent chromium. Hydrogen sulfide reacts with copper, lead, and cadmium to form precipitated metal sulfides. Alkali is then used to adjust the precipitate of divalent iron and trivalent chromium to hydroxide. During the pH adjustment process, the aluminum hydroxide generated has a flocculating effect, which can accelerate the precipitation rate of iron, cadmium, nickel, copper, lead, and cadmium precipitates, and has a significant wastewater treatment effect.

[0018] The treatment agent is added to the wastewater after aluminum ash treatment, and the treatment agent can be recycled 20 to 30 times. The outer layer material with a porous structure can increase the removal effect of COD and ammonia nitrogen in the wastewater. After the core layer material is wrapped, it also has a longer-term use effect, achieving the overall purpose of excellent removal rate and removal effect. DETAILED DESCRIPTION

[0019] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with its embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and do not limit the scope of protection of the present invention.

[0020] Unless otherwise defined, all technical and scientific terms used herein have the same meanings as commonly understood by one skilled in the art to which this invention pertains. The terms used in this specification of the present invention are for the purpose of describing specific embodiments only and are not intended to limit the present invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0021] A method for treating stainless steel pickling wastewater with molten aluminum ash in one embodiment of the present invention comprises the following steps:

[0022] Add molten aluminum ash to the stainless steel pickling wastewater, stir for 2h~5h, and after the first static treatment, adjust the pH, filter, and discharge the treated wastewater into another treatment tank;

[0023] Adding a treatment agent into the treated wastewater, stirring it and allowing it to stand for a second time, filtering it, and discharging the water;

[0024] The treatment agent is a composite particle, which consists of a core layer and an outer layer wrapping the core layer. The material of the core layer is prepared from modified carbon powder, silicon nitride, starch and shell powder in a mass ratio of (1~3): (1~7): (1~3): 1; the material of the outer layer is a porous material, which is prepared from a mixture of epoxy resin, silicon dioxide and diatomaceous earth in a mass ratio of (0.5~1.2): (1~3): (5~7).

[0025] In one embodiment, the addition amount of the molten cast aluminum ash is 18g / 100mL~25g / 100mL.

[0026] In one embodiment, the first standing treatment time is 2h~5h.

[0027] In one embodiment, the addition amount of the treatment agent is 1 g / 100 mL to 15 g / 100 mL.

[0028] In one embodiment, the stirring process is performed at a speed of 50 r / min to 120 r / min, and the stirring time is 30 min to 45 min.

[0029] In one embodiment, the second standing treatment time is 1 hour to 3 hours.

[0030] In one embodiment, the preparation method of the modified carbon powder is as follows: after the corn stalks are crushed, they are treated with supercritical carbon dioxide at a treatment pressure of 5 MPa, a treatment time of 30 min to 40 min, a carbonization temperature of 400°C, and a carbonization time of 1 h to 2 h, and then dispersed in an acetic acid solution, soaked at a temperature of 65°C to 75°C for 1 h to 2 h, filtered, and the filter residue is dispersed in a sodium hydroxide solution, soaked at a temperature of 45°C to 65°C for 1 h to 2 h, filtered, and washed with water to obtain the modified carbon powder.

[0031] In one embodiment, the preparation method of the core layer material is: adding modified carbon powder, silicon nitride, starch and shell powder into deionized water, ultrasonically treating for 1h~2h, concentrating, drying and granulating to obtain the core layer material.

[0032] In one embodiment, the porous material is prepared by adding silicon dioxide and diatomaceous earth to an appropriate amount of deionized water, stirring for 20 to 30 minutes, adding epoxy resin, and continuing to stir for 35 to 45 minutes to obtain the outer layer material.

[0033] In one embodiment, the composite particles are prepared by wrapping the outer layer material with the core layer material in a mass ratio of (3-5): (1-3), calcining at 550-580°C for 1-2 hours, and cooling.

[0034] The above scheme has a significant adsorption treatment effect, so that after the stainless steel pickling wastewater is treated, the total chromium, nickel, iron, copper, cadmium and lead contents meet the national pollutant emission standards.

[0035] The embodiments of the present invention will be described in detail below with reference to specific examples.

[0036] Example 1:

[0037] A method for treating stainless steel pickling wastewater with molten aluminum ash, the method comprising the following steps:

[0038] Add molten aluminum ash to the stainless steel pickling wastewater at a rate of 20g / 100mL, stir for 2h, let it stand for the first time for 3h, adjust the pH, filter, and discharge the treated wastewater into another treatment tank;

[0039] The treatment agent was added into the treated wastewater at an addition amount of 11 g / 100 mL, stirred at a stirring speed of 50 r / min for 40 min, and then allowed to stand for a second time for 2 h, filtered, and the water was discharged.

[0040] The preparation method of the treatment agent in Example 1 is as follows:

[0041] The corn stalks were crushed and treated with supercritical carbon dioxide at a pressure of 5 MPa for 35 minutes, a carbonization temperature of 400°C for 2 hours, and then dispersed in an acetic acid solution and soaked at 70°C for 1 hour. The residue was filtered and dispersed in a sodium hydroxide solution and soaked at 45°C for 1 hour. The residue was filtered and washed with water to obtain modified carbon powder. The modified carbon powder, silicon nitride, starch and shell powder in a mass ratio of 2:6:1:1 were added to deionized water and ultrasonically treated for 1 hour. The core layer material was obtained after concentration, drying and granulation.

[0042] Add silica and diatomaceous earth to an appropriate amount of deionized water, stir for 30 minutes, then add epoxy resin and continue stirring for 35 minutes to obtain the outer layer material, wherein the mass ratio of epoxy resin, silica and diatomaceous earth is 0.8:3:6;

[0043] The outer layer material is wrapped around the core layer material at a mass ratio of 5:1, and then calcined at 550°C for 2h, and composite particles are obtained after cooling.

[0044] Example 2:

[0045] A method for treating stainless steel pickling wastewater with molten aluminum ash, the method comprising the following steps:

[0046] Add molten aluminum ash to the stainless steel pickling wastewater at a rate of 19 g / 100 mL, stir for 2 hours, let it sit for the first time for 3 hours, adjust the pH, filter, and discharge the treated wastewater into another treatment tank;

[0047] The treatment agent was added into the treated wastewater at an addition amount of 9 g / 100 mL, and the mixture was stirred at a stirring speed of 50 r / min for 45 min, and then allowed to stand for a second time for 2 h, filtered, and the water was discharged.

[0048] The preparation method of the treatment agent in Example 2 is as follows:

[0049] The corn stalks were crushed and treated with supercritical carbon dioxide at a pressure of 5 MPa for 30 minutes and a carbonization temperature of 400°C for 2 hours. The stalks were then dispersed in an acetic acid solution and soaked at 65°C for 2 hours. The residues were filtered and dispersed in a sodium hydroxide solution and soaked at 60°C for 2 hours. The residues were filtered and washed with water to obtain modified carbon powder. The modified carbon powder, silicon nitride, starch, and shell powder in a mass ratio of 3:5:1:1 were added to deionized water and ultrasonically treated for 1 hour. The core layer material was obtained after concentration, drying, and granulation.

[0050] Add silica and diatomaceous earth to an appropriate amount of deionized water, stir for 25 minutes, then add epoxy resin and continue stirring for 40 minutes to obtain the outer layer material, wherein the mass ratio of epoxy resin, silica and diatomaceous earth is 1:3:6;

[0051] The outer layer material is wrapped around the core layer material at a mass ratio of 5:1, and then calcined at 550°C for 2h, and composite particles are obtained after cooling.

[0052] Example 3:

[0053] A method for treating stainless steel pickling wastewater with molten aluminum ash, the method comprising the following steps:

[0054] Add molten aluminum ash to the stainless steel pickling wastewater at a rate of 20g / 100mL, stir for 2h, let it stand for the first time for 3h, adjust the pH, filter, and discharge the treated wastewater into another treatment tank;

[0055] The treatment agent was added into the treated wastewater at an addition amount of 10 g / 100 mL, stirred at a stirring speed of 50 r / min for 30 min, and then allowed to stand for a second time for 1 h, filtered, and the water was discharged.

[0056] The preparation method of the treatment agent in Example 3 is as follows:

[0057] The corn stalks were crushed and treated with supercritical carbon dioxide at a pressure of 5 MPa for 30 min, a carbonization temperature of 400°C for 2 h, and then dispersed in an acetic acid solution and soaked at 65°C for 2 h. The residue was filtered and dispersed in a sodium hydroxide solution and soaked at 60°C for 1 h. The residue was filtered and washed with water to obtain modified carbon powder. The modified carbon powder, silicon nitride, starch and shell powder in a mass ratio of 3:5:1:1 were added to deionized water and ultrasonically treated for 1 h. The core layer material was obtained after concentration, drying and granulation.

[0058] Add silica and diatomaceous earth to an appropriate amount of deionized water, stir for 30 minutes, then add epoxy resin and continue stirring for 35 minutes to obtain the outer layer material, wherein the mass ratio of epoxy resin, silica and diatomaceous earth is 1:3:5;

[0059] The outer layer material is wrapped around the core layer material at a mass ratio of 5:1, and then calcined at 550°C for 2h, and composite particles are obtained after cooling.

[0060] Comparative Example 1:

[0061] The difference between Comparative Example 1 and Example 3 is that no aluminum ash treatment is added in Comparative Example 1, and the rest is the same as Example 3.

[0062] Comparative Example 2:

[0063] The difference between Comparative Example 2 and Example 3 is that no treatment agent is added in Comparative Example 2, and the other parts are the same as Example 3.

[0064] Comparative Example 3:

[0065] Compared with Example 3, Comparative Example 3 differs in that carbon powder is used instead of composite particles in Comparative Example 3, and the rest is the same as Example 3.

[0066] The water solutions treated in Examples 1 to 3 and the water solutions treated in Comparative Examples 1 to 3 were tested for the contents of total chromium, total nickel, total iron, and total copper. The results are shown in Table 1 below.

[0067] Table 1: Contents of total chromium, total nickel, total iron and total copper

[0068]

[0069] From the data in Table 1, it can be analyzed that after the dual treatment of aluminum ash and treatment agent, the present application can obtain more significant treatment effect. After the stainless steel pickling wastewater is treated, the content of total chromium, total nickel, total iron and total copper meets the national pollutant emission standards.

[0070] In addition, the water liquids treated in Examples 1 to 3 and the water liquids treated in Comparative Examples 1 to 3 were tested for CODcr (mg / L), SS (mg / L), ammonia nitrogen (mg / L) and turbidity. The results are shown in Table 2 below.

[0071] Table 2: Test results of CODcr, SS, ammonia nitrogen and turbidity

[0072] Table 2:

[0073]

[0074] As can be seen from Table 2, it is further illustrated that the present application has a more significant treatment effect by combining aluminum ash and a treatment agent.

[0075] The technical features of the above-mentioned embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above-mentioned embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0076] The above-described embodiments merely illustrate several implementations of the present invention, and while their descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent. It should be noted that a person skilled in the art would be able to make numerous variations and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the patent for this invention shall be determined by the appended claims.

Claims

1. A method for treating stainless steel pickling wastewater with molten aluminum ash, characterized in that: The method comprises the following steps: Add molten aluminum ash to the stainless steel pickling wastewater, stir for 2h~5h, and after the first static treatment, adjust the pH, filter, and discharge the treated wastewater into another treatment tank; Adding a treatment agent into the treated wastewater, stirring it and allowing it to stand for a second time, filtering it, and discharging the water; The treatment agent is a composite particle, which consists of a core layer and an outer layer wrapping the core layer. The core layer is made of modified carbon powder, silicon nitride, starch, and shell powder in a mass ratio of (1-3): (1-7): (1-3): 1; the outer layer is a porous material, which is made of epoxy resin, silicon dioxide, and diatomaceous earth in a mass ratio of (0.5-1.2): (1-3): (5-7); The modified carbon powder preparation method comprises the following steps: crushing corn stalks, treating them with supercritical carbon dioxide at a pressure of 5 MPa for 30 to 40 minutes, a carbonization temperature of 400° C. for 1 to 2 hours, dispersing them in an acetic acid solution, soaking them at a temperature of 65 to 75° C. for 1 to 2 hours, filtering them, and dispersing the residues in a sodium hydroxide solution, soaking them at a temperature of 45 to 65° C. for 1 to 2 hours, filtering them, and washing them with water to obtain the modified carbon powder. The preparation method of the core layer material is as follows: adding modified carbon powder, silicon nitride, starch and shell powder into deionized water, ultrasonically treating for 1 hour to 2 hours, concentrating, drying and granulating to obtain the core layer material; The porous material is prepared by adding silicon dioxide and diatomaceous earth to an appropriate amount of deionized water, stirring for 20 to 30 minutes, adding epoxy resin, and continuing to stir for 35 to 45 minutes to obtain the outer layer material; The composite particles are prepared by wrapping the outer layer material on the core layer material in a mass ratio of (3-5) to (1-3) of the outer layer material to the core layer material, calcining the outer layer material at 550-580°C for 1-2 hours, and cooling the composite particles.

2. The method according to claim 1, characterized in that The addition amount of the molten cast aluminum ash is 18g / 100mL~25g / 100mL.

3. The method according to claim 1, characterized in that The time for the first standing treatment is 2h~5h.

4. The method according to claim 1, wherein The addition amount of the treatment agent is 1g / 100mL~15g / 100mL.

5. The method according to claim 1, wherein The stirring speed after adding the treatment agent is 50r / min~120r / min, and the time is 30min~45min.

6. The method according to claim 1, characterized in that The second standing treatment time is 1h~3h.

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