Method for preparing ferrite material from steel sulfuric acid pickling waste liquid and ferrite material

Abstract

The invention discloses a method for preparing a ferrite material from steel sulfuric acid pickling waste liquid and the ferrite material.The method comprises the following steps that S1, a NaOH solution is added into the steel sulfuric acid pickling waste liquid to adjust the pH value, and mixed liquid is obtained after even mixing; s2, hydrothermal reaction: putting the mixed solution into a hydrothermal reaction kettle, putting the hydrothermal reaction kettle into a drying oven for hydrothermal reaction, and then naturally cooling to room temperature; s3, carrying out centrifugal treatment on the mixed solution after the hydrothermal reaction, and carrying out solid-liquid separation to obtain supernate and a solid-phase substance; s4, cleaning, centrifuging, drying and grinding the solid-phase substance, and sieving to obtain ferrite powder; s5, adding an adhesive into the ferrite powder, uniformly mixing, and pressing into a prefabricated block; and S6, putting the prefabricated block into a muffle furnace, carrying out high-temperature calcination and heat preservation in a reducing atmosphere, cooling to room temperature, and carrying out polishing treatment to obtain the ferrite material. According to the invention, double targets of sulfuric acid pickling waste liquid treatment and resource recovery can be realized.

Description

Technical Field

[0001] The invention belongs to the technical field of resource utilization of pickling waste liquid, and relates to a method for preparing ferrite material from steel sulfuric acid pickling waste liquid and the ferrite material. Background Art

[0002] The pH value of steel pickling wastewater is generally below 1.5, which is strongly acidic and contains heavy metal ions and other harmful substances. If it is discharged directly, it will cause serious pollution to the receiving water and soil, and also cause waste of resources. In recent years, the resource application of waste acid has gradually attracted the attention of scholars at home and abroad. At present, the treatment processes of sulfuric acid pickling wastewater mainly include neutralization method, iron sulfate salt method, organic solution extraction method, dialysis method, ion exchange method, etc. In recent years, with the frequent mention of "zero discharge" of wastewater in the industrial field, foreign countries have begun to implement diffusion dialysis-diaphragm electrolysis, biosorption, micelle enhanced ultrafiltration and other processes to treat sulfuric acid pickling wastewater, but there are still problems such as low treatment efficiency and high cost.

[0003] In view of the above situation, it is urgent to study a method that can efficiently treat steel sulfuric acid pickling waste liquid, so as to solve the problems of low treatment efficiency and high cost in the existing technology and achieve the dual goals of steel sulfuric acid pickling waste liquid treatment and resource recovery. Summary of the invention

[0004] In view of the above-mentioned defects existing in the prior art, the purpose of the present invention is to provide a method for preparing ferrite material from steel sulfuric acid pickling waste liquid and ferrite material, which utilizes the hydrothermal method to efficiently realize the resource utilization of sulfuric acid pickling waste liquid, reduce costs and energy consumption, and the prepared magnetic ferrite material product has good magnetic properties and excellent chemical stability, meeting the needs of the magnetic material field, and achieving the dual goals of sulfuric acid pickling waste liquid treatment and resource recovery.

[0005] To achieve the above object, the present invention adopts the following technical solution:

[0006] The first aspect of the present invention provides a method for preparing ferrite material from steel sulfuric acid pickling waste liquid, comprising the following steps:

[0007] S1, adding NaOH solution to the steel sulfuric acid pickling waste liquid to adjust the pH value, and mixing them evenly to obtain a mixed solution;

[0008] S2, hydrothermal reaction, placing the mixed solution in a hydrothermal reaction kettle, placing it in an oven for hydrothermal reaction, and then naturally cooling it to room temperature;

[0009] S3, centrifuging the mixed solution after the hydrothermal reaction to obtain a supernatant and a solid phase after solid-liquid separation;

[0010] S4, washing, centrifuging, drying, grinding and sieving the solid phase to obtain ferrite powder;

[0011] S5, adding a binder to the ferrite powder, mixing evenly and pressing into a prefabricated block;

[0012] S6, placing the prefabricated block into a muffle furnace, calcining and keeping it warm at high temperature in a reducing atmosphere, and grinding it after cooling it to room temperature to obtain a ferrite material.

[0013] Preferably, in step S1, the pH value of the steel sulfuric acid pickling wastewater is 0.2-0.6.

[0014] Preferably, in step S1, the pH value of the steel sulfuric acid pickling waste liquid is adjusted to 8-12 with a NaOH solution.

[0015] Preferably, in step S2, the oven temperature is set to 150-180° C., and the hydrothermal reaction time is 8-16 hours.

[0016] Preferably, in step S3, during the centrifugal treatment, the centrifugal speed is 3000-4000 r / min, and the centrifugal separation time is 10-15 min.

[0017] Preferably, in step S3, the removal rates of Cr, Cu, Fe, Ni, Pb and Zn metal ions in the supernatant are all above 99%.

[0018] Preferably, in step S4, the washing water temperature during the washing is 40-50°C.

[0019] Preferably, in step S5, the binder is polyvinyl alcohol, and its amount is 3-5% of the mass of the ferrite powder.

[0020] Preferably, in step S6:

[0021] The high temperature calcination temperature is 600-800°C and the calcination time is 4-6h;

[0022] The insulation temperature is 200-400° C., and the insulation time is 2-4 hours.

[0023] The second aspect of the present invention provides a ferrite material prepared by the method for preparing ferrite material from steel sulfuric acid pickling waste liquid according to the first aspect of the present invention, wherein the Fe2O3 content of the ferrite material is ≥90% and the saturation magnetization intensity is ≥60emu / g.

[0024] The present invention has the following beneficial effects:

[0025] 1. The present invention can efficiently remove pollutants: The hydrothermal method can effectively convert pollutants such as heavy metal ions in steel sulfuric acid pickling waste liquid into stable inorganic substances or easily separable forms under high temperature and high pressure conditions, thereby achieving efficient removal;

[0026] 2. The present invention can realize resource recycling: in the hydrothermal treatment process, valuable metals and other resources in the steel sulfuric acid pickling waste liquid can be recovered, thus realizing the recycling of resources and reducing costs;

[0027] 3. The present invention can reduce secondary pollution: Compared with traditional treatment methods such as neutralization method, the hydrothermal method produces less secondary pollution, because it does not require the addition of a large amount of chemical reagents during the treatment process, and the generated products are relatively stable and are not easy to cause new environmental pollution;

[0028] 4. The present invention is easy and safe to operate: the hydrothermal method is relatively easy to operate, and due to its closed system characteristics, it can reduce the safety risks of the operation process and improve the processing efficiency;

[0029] 5. The present invention combines the treatment of steel sulfuric acid pickling waste liquid with the preparation of magnetic materials, and uses the hydrothermal method to efficiently realize the resource utilization of sulfuric acid pickling waste liquid, thereby reducing costs and energy consumption. In addition, the prepared magnetic ferrite material product has good magnetic properties and excellent chemical stability, meeting the needs of the magnetic material field;

[0030] 6. The present invention mixes steel sulfuric acid pickling waste liquid with sodium hydroxide solution, adjusts the pH value, and then places the mixed liquid in a hydrothermal reactor for hydrothermal reaction, and performs solid-liquid separation in a centrifuge until a solid phase and a supernatant are obtained. The solid phase is washed with warm water and then centrifuged, dried at a certain temperature and then ground to obtain ferrite powder, and then the ferrite powder and a binder are placed in a mold and pressed to a desired density and shape by a press, and then the product is placed in a high-temperature muffle furnace in a reducing atmosphere for sintering, and after calcination, it is taken out and its surface is polished after cooling to obtain a ferrite material with good magnetic properties and excellent chemical stability. At the same time, this process effectively purifies the steel sulfuric acid pickling waste liquid, achieving the dual goals of steel sulfuric acid pickling waste liquid treatment and resource recovery;

[0031] 7. The method of preparing magnetic ferrite material by using sulfuric acid pickling waste liquid is simple, not easy to produce secondary pollution, and the prepared magnetic ferrite material has excellent chemical stability. The heavy metal removal rate of the supernatant is greater than 99%, which can achieve the goal of treating waste with waste and recycling resources. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 It is a schematic flow chart of a method for preparing ferrite material from steel sulfuric acid pickling waste liquid of the present invention;

[0033] Figure 2 is a SEM image of the ferrite material prepared in Example 1 of the present invention;

[0034] Figure 3 is a SEM image of the ferrite material prepared in Example 2 of the present invention;

[0035] Figure 4 is a SEM image of the ferrite material prepared in Example 3 of the present invention;

[0036] Figure 5 This is a SEM image of the ferrite material prepared in Example 4 of the present invention. DETAILED DESCRIPTION

[0037] In order to better understand the above technical solution of the present invention, the technical solution of the present invention is further described below in conjunction with embodiments.

[0038] Combination Figure 1 As shown, the present invention provides a method for preparing ferrite material from steel sulfuric acid pickling waste liquid, comprising the following steps:

[0039] S1, adding NaOH solution to the steel sulfuric acid pickling waste liquid to adjust the pH value, and mixing them evenly to obtain a mixed solution;

[0040] In this step, iron and steel sulfuric acid pickling waste liquid is used as raw material, NaOH solution is added thereto to adjust the pH value to 10-12, and the mixture is fully mixed to obtain a mixed solution; wherein, the pH value of the iron and steel sulfuric acid pickling waste liquid is 0.2-0.6; and the concentration of the NaOH solution used can be 5 mol / L.

[0041] S2, hydrothermal reaction, placing the mixed solution in a hydrothermal reaction kettle, placing it in an oven for hydrothermal reaction, and then naturally cooling it to room temperature;

[0042] This step is mainly a hydrothermal reaction. The mixed liquid treated in step S1 is loaded into a hydrothermal reaction kettle, and then placed in an oven together with the hydrothermal reaction kettle to heat up. After keeping it for a period of time, it is naturally cooled to room temperature and then taken out; wherein, the oven temperature is set to 150-180°C, and the hydrothermal reaction time is 8-16h.

[0043] S3, centrifuging the mixed solution after the hydrothermal reaction to obtain a supernatant and a solid phase after solid-liquid separation;

[0044] This step is a centrifugal treatment. The mixed liquid after the hydrothermal reaction is placed in a centrifuge tube and centrifuged for a period of time until the solid-liquid separation obtains a supernatant and a solid phase. During the centrifugal treatment, the centrifugal speed is 3000-4000r / min, and the centrifugal separation time is 10-15min. The supernatant can be collected and retained to measure the heavy metal content in it. The test results show that the removal rate of Cr, Cu, Fe, Ni, Pb, and Zn metal ions in the supernatant is more than 99%.

[0045] S4, washing, centrifuging, drying, grinding and sieving the solid phase to obtain ferrite powder;

[0046] In this step, the solid phase obtained in step S3 is washed with warm water at 40-50°C, and after centrifugation, the solid phase is placed in an oven to dry for a certain period of time, and then taken out, and then ground. After grinding, it is sieved through a 200-mesh sieve to obtain ferrite powder.

[0047] S5, adding a binder to the ferrite powder, mixing evenly and pressing into a prefabricated block;

[0048] In this step, a binder is added to the ground ferrite powder, mixed evenly, put into a mold, and pressed into a block under a hydraulic press. The binder is polyvinyl alcohol, and its amount is 3-5% of the mass of the ferrite powder.

[0049] S6, placing the prefabricated block into a muffle furnace, calcining and keeping it warm at high temperature in a reducing atmosphere, and grinding it after cooling it to room temperature to obtain a ferrite material.

[0050] In this step, the prefabricated block obtained in step S5 is placed in a muffle furnace, calcined at high temperature in a reducing atmosphere, then taken out after being kept warm, and its surface is polished after being cooled to room temperature, so as to obtain a ferrite material with high saturation magnetization. The high-temperature calcination temperature is 600-800°C, the calcination time is 4-6h; the insulation temperature is 200-400°C, and the insulation time is 2-4h.

[0051] The Fe2O3 content of the ferrite material prepared above is ≥90%, and the saturation magnetization is ≥60emu / g.

[0052] In the above-mentioned specific operation process, the fine control of key parameters such as hydrothermal reaction temperature, reaction time and solution pH value can significantly affect the performance and quality of the final product. Therefore, it is very important to optimize these parameters according to different experimental purposes and requirements. The present invention adopts the response surface method (Response Surface Methodology, RSM) to determine the optimal preparation conditions. The method was first proposed by George EPBox and KG Wilson, pioneers in the statistical community, and the relationship between different variables is estimated by regression analysis, especially how multiple factors act on the experimental results, that is, the response value. In the application of the present invention, the factors affecting the hydrothermal reaction are first determined by preliminary experiments, and then a series of experiments are designed to systematically change the levels of these factors and record the corresponding experimental results. The response surface method of this patent determines that the quadratic polynomial regression equation between the independent variables (pH value A, reaction time B and reaction temperature C) and the dependent variable (saturation magnetization intensity Y) is: Y = 59.66 + 9.60A + 1.13B + 20.02C + 12.25AB-2.79AC-3.17BC-5.59A 2 +0.5290B 2 -16.88C 2 , the R of this equation 2 It is 0.9821, so the quadratic model has a high degree of fit, and the experimental data is basically consistent with the model.

[0053] The method for preparing ferrite material from steel sulfuric acid pickling waste liquid and the ferrite material of the present invention are further introduced below with reference to specific examples.

[0054] Example 1

[0055] The method for preparing ferrite material from steel sulfuric acid pickling waste liquid in this embodiment is as follows:

[0056] (1) Using steel sulfuric acid pickling waste liquid as raw material, adding a 5 mol / L NaOH solution to adjust the pH value to 12, and mixing well to obtain a mixed solution;

[0057] (2) placing the mixed solution in a hydrothermal reaction kettle, placing it in an oven for hydrothermal reaction, controlling the hydrothermal reaction temperature to 150° C., the hydrothermal time to 16 h, and naturally cooling to room temperature after the reaction is completed;

[0058] (3) The mixed solution after the hydrothermal reaction was centrifuged at a centrifugal speed of 3000 r / min for 10 to 15 minutes to obtain a supernatant and a solid phase after solid-liquid separation; the supernatant was tested for components, and the results are shown in Table 2;

[0059] (4) The solid phase was washed, dried, ground, and passed through a 200-mesh sieve to obtain ferrite powder; the obtained ferrite powder was subjected to VSM test and XRF test, and the saturation magnetization intensity of the ferrite powder was found to be 72.68emu / g and the Fe2O3 content was 92.33%. The results are shown in Table 1.

[0060] (5) adding a binder (polyvinyl alcohol, the amount of which is 0.3 g, which is 3% of the mass of the ferrite powder) to the ferrite powder, mixing well and pressing into a prefabricated block;

[0061] (6) The prefabricated block is placed in a muffle furnace and calcined at 800°C for 4 hours in a reducing atmosphere, then kept at 400°C for 2 hours, cooled to room temperature, and then polished to obtain a magnetic ferrite material with high saturation magnetization.

[0062] The magnetic ferrite material prepared above was tested by SEM, and the results were as follows: Figure 2 As shown, the grain size of the magnetic ferrite material is uniform and the crystallization is complete.

[0063] Example 2

[0064] The method for preparing ferrite material from steel sulfuric acid pickling waste liquid in this embodiment is as follows:

[0065] (1) Using steel sulfuric acid pickling waste liquid as raw material, adding a 5 mol / L NaOH solution to adjust the pH value to 10, and mixing evenly to obtain a mixed solution;

[0066] (2) placing the mixed solution in a hydrothermal reaction kettle, placing it in an oven for hydrothermal reaction, controlling the hydrothermal reaction temperature to 150° C., the hydrothermal time to 12 h, and naturally cooling to room temperature after the reaction is completed;

[0067] (3) The mixed solution after the hydrothermal reaction was centrifuged at a centrifugal speed of 3000 r / min for 10 to 15 minutes to obtain a supernatant and a solid phase after solid-liquid separation; the supernatant was tested for components, and the results are shown in Table 2;

[0068] (4) The solid phase was washed, dried, ground, and passed through a 200-mesh sieve to obtain ferrite powder; the obtained ferrite powder was subjected to VSM test and XRF test, and the saturation magnetization intensity of the ferrite powder was found to be 60.86emu / g and the Fe2O3 content was 92.92%. The results are shown in Table 1.

[0069] (5) adding a binder (polyvinyl alcohol, the amount of which is 0.3 g, which is 3% of the mass of the ferrite powder) to the ferrite powder, mixing well and pressing into a prefabricated block;

[0070] (6) The prefabricated block is placed in a muffle furnace and calcined at 800°C for 4 hours in a reducing atmosphere, then kept at 400°C for 2 hours, cooled to room temperature, and then polished to obtain a magnetic ferrite material with high saturation magnetization.

[0071] The magnetic ferrite material prepared above was tested by SEM, and the results were as follows: Figure 3 As shown, the grain size of the magnetic ferrite material is uniform and the crystallization is complete.

[0072] Example 3

[0073] The method for preparing ferrite material from steel sulfuric acid pickling waste liquid in this embodiment is as follows:

[0074] (1) Using steel sulfuric acid pickling waste liquid as raw material, adding a 5 mol / L NaOH solution to adjust the pH value to 12, and mixing well to obtain a mixed solution;

[0075] (2) placing the mixed solution in a hydrothermal reaction kettle, placing it in an oven for hydrothermal reaction, controlling the hydrothermal reaction temperature to 180° C., the hydrothermal time to 12 h, and naturally cooling to room temperature after the reaction;

[0076] (3) The mixed solution after the hydrothermal reaction was centrifuged at a centrifugal speed of 3000 r / min for 10 to 15 minutes to obtain a supernatant and a solid phase after solid-liquid separation; the supernatant was tested for components, and the results are shown in Table 2;

[0077] (4) The solid phase was washed, dried, ground, and passed through a 200-mesh sieve to obtain ferrite powder; the obtained ferrite powder was subjected to VSM test and XRF test, and the saturation magnetization intensity of the ferrite powder was found to be 67.74emu / g and the Fe2O3 content was 93.80%. The results are shown in Table 1.

[0078] (5) adding a binder (polyvinyl alcohol, the amount of which is 0.5 g, which is 5% of the mass of the ferrite powder) to the ferrite powder, mixing well and pressing into a prefabricated block;

[0079] (6) The prefabricated block is placed in a muffle furnace and calcined at 800°C for 4 hours in a reducing atmosphere, then kept at 400°C for 2 hours, cooled to room temperature, and then polished to obtain a magnetic ferrite material with high saturation magnetization.

[0080] The magnetic ferrite material prepared above was tested by SEM, and the results were as follows: Figure 4 As shown, the grain size of the magnetic ferrite material is uniform and the crystallization is complete.

[0081] Example 4

[0082] The method for preparing ferrite material from steel sulfuric acid pickling waste liquid in this embodiment is as follows:

[0083] (1) Using steel sulfuric acid pickling waste liquid as raw material, adding a 5 mol / L NaOH solution to adjust the pH value to 8, and mixing evenly to obtain a mixed solution;

[0084] (2) placing the mixed solution in a hydrothermal reaction kettle, placing it in an oven for hydrothermal reaction, controlling the hydrothermal reaction temperature to 150° C., the hydrothermal time to 8 h, and naturally cooling to room temperature after the reaction is completed;

[0085] (3) The mixed solution after the hydrothermal reaction was centrifuged at a centrifugal speed of 3000 r / min for 10 to 15 minutes to obtain a supernatant and a solid phase after solid-liquid separation; the supernatant was tested for components, and the results are shown in Table 2;

[0086] (4) The solid phase was washed, dried, ground, and passed through a 200-mesh sieve to obtain ferrite powder; the obtained ferrite powder was subjected to VSM test and XRF test, and the saturation magnetization intensity of the ferrite powder was found to be 61.01emu / g and the Fe2O3 content was 90.19%. The results are shown in Table 1.

[0087] (5) adding a binder (polyvinyl alcohol, the amount of which is 0.3 g, which is 3% of the mass of the ferrite powder) to the ferrite powder, mixing well and pressing into a prefabricated block;

[0088] (6) The prefabricated block is placed in a muffle furnace and calcined at 800°C for 4 hours in a reducing atmosphere, then kept at 400°C for 2 hours, cooled to room temperature, and then polished to obtain a magnetic ferrite material with high saturation magnetization.

[0089] The magnetic ferrite material prepared above was tested by SEM, and the results were as follows: Figure 5 As shown, the grain size of the magnetic ferrite material is uniform and the crystallization is complete.

[0090] Table 1 Experimental data records of the embodiment

[0091]

[0092] Table 2 ICP test results of heavy metal concentrations of waste acid stock solution and supernatant of Examples 1 to 4

[0093]

[0094] Table 2 shows the ICP test results of heavy metal concentrations in the waste acid stock solution and the supernatant of Examples 1 to 4. By using the method of the present invention, the removal rates of Cr, Cu, Fe, Ni, Pb, and Zn metal ions in the supernatant are all above 99%, and the Na2SO4 attached to the solid phase product can be effectively removed after washing with warm water. The Fe2O3 content of the prepared ferrite material is ≥90%, and the saturation magnetization intensity is ≥60emu / g.

[0095] In summary, the present invention uses steel sulfuric acid pickling waste liquid as raw material and prepares magnetic ferrite material through hydrothermal treatment. The method of preparing magnetic ferrite material using sulfuric acid pickling waste liquid is simple, not easy to produce secondary pollution, and the prepared magnetic ferrite material has excellent chemical stability, and the heavy metal removal rate of the supernatant is greater than 99%, which can achieve the goal of treating waste with waste and resource utilization.

[0096] Those skilled in the art should recognize that the above embodiments are only used to illustrate the present invention, and are not intended to limit the present invention. As long as they are within the spirit of the present invention, any changes or modifications to the above embodiments will fall within the scope of the claims of the present invention.

Claims

1. A method for preparing ferrite material from steel sulfuric acid pickling waste liquid, characterized in that: The following steps are involved: S1, adding NaOH solution to the steel sulfuric acid pickling waste liquid to adjust the pH value, and mixing them evenly to obtain a mixed solution; S2, hydrothermal reaction, placing the mixed solution in a hydrothermal reaction kettle, placing it in an oven for hydrothermal reaction, and then naturally cooling it to room temperature; S3, centrifuging the mixed solution after the hydrothermal reaction to obtain a supernatant and a solid phase after solid-liquid separation; S4, washing, centrifuging, drying, grinding and sieving the solid phase to obtain ferrite powder; S5, adding a binder to the ferrite powder, mixing evenly and pressing into a prefabricated block; S6, placing the prefabricated block into a muffle furnace, calcining and keeping it warm at high temperature in a reducing atmosphere, and grinding it after cooling it to room temperature to obtain a ferrite material.

2. The method for preparing ferrite material from steel sulfuric acid pickling waste liquid according to claim 1, characterized in that: In the step S1, the pH value of the steel sulfuric acid pickling wastewater is 0.2-0.

6.

3. The method for preparing ferrite material from steel sulfuric acid pickling waste liquid according to claim 1, characterized in that: In the step S1, the pH value of the steel sulfuric acid pickling waste liquid is adjusted to 8-12 with a NaOH solution.

4. The method for preparing ferrite material from steel sulfuric acid pickling waste liquid according to claim 1, characterized in that: In step S2, the oven temperature is set to 150-180° C., and the hydrothermal reaction time is 8-16 hours.

5. The method for preparing ferrite material from steel sulfuric acid pickling waste liquid according to claim 1, characterized in that: In the step S3, during the centrifugal treatment, the centrifugal speed is 3000-4000 r / min, and the centrifugal separation time is 10-15 min.

6. The method for preparing ferrite material from steel sulfuric acid pickling waste liquid according to claim 1, characterized in that: In step S3, the removal rates of Cr, Cu, Fe, Ni, Pb and Zn metal ions in the supernatant are all above 99%.

7. The method for preparing ferrite material from steel sulfuric acid pickling waste liquid according to claim 1, characterized in that: In the step S4, the washing water temperature during the washing is 40-50°C.

8. The method for preparing ferrite material from steel sulfuric acid pickling waste liquid according to claim 1, characterized in that: In the step S5, the binder is polyvinyl alcohol, and the amount thereof is 3-5% of the mass of the ferrite powder.

9. The method for preparing ferrite material from steel sulfuric acid pickling waste liquid according to claim 1, characterized in that: In step S6: The high temperature calcination temperature is 600-800°C and the calcination time is 4-6h; The insulation temperature is 200-400° C., and the insulation time is 2-4 hours.

10. A ferrite material prepared by the method for preparing ferrite material from steel sulfuric acid pickling waste liquid according to any one of claims 1 to 9, characterized in that: The Fe2O3 content of the ferrite material is ≥90%, and the saturation magnetization intensity is ≥60emu / g.

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