Composite metal oxide curing agent and application thereof in sulfur-fixing and arsenic-fixing harmless treatment of arsenic sulfide slag

Abstract

The invention discloses a composite metal oxide curing agent and application thereof in sulfur-fixing and arsenic-fixing harmless treatment of arsenic sulfide slag, and relates to the technical field of hazardous waste harmless treatment. The composite metal oxide curing agent is prepared from the following components: 30 to 45 weight percent of Fe2O3, 20 to 30 weight percent of Al2O3, 15 to 25 weight percent of CaO, 5 to 10 weight percent of SiO2, 1 to 3 weight percent of TiO2, 3 to 5 weight percent of bentonite binder and 0.5 to 2 weight percent of citric acid accelerant. The preparation method comprises the following steps: step 1, raw material pretreatment; step 2, carrying out sol-gel synthesis; step 3, calcining treatment; step 4, function strengthening; and step 5, forming and packaging. FeAl2O4 is formed through a spinel structure to achieve lattice curing of arsenic, sulfate stabilization is promoted through the calcium-sulfur synergistic effect, the energy consumption is reduced by 30% or above through the low-temperature calcination technology, and when the curing agent is applied to sulfur and arsenic fixing harmless treatment of arsenic sulfide residues, the content of leached arsenic can be smaller than or equal to 0.3 mg / L.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of harmless treatment of hazardous waste, in particular to a composite metal oxide solidifying agent and its application in sulfur-arsenic solidification and arsenic solidification harmless treatment of arsenic sulfide residue. BACKGROUND

[0002] Arsenic sulfide residue is a typical hazardous waste generated in the metallurgical, chemical and other industries, containing As(III) / As(V) and elemental sulfur and other toxic components, which is easy to cause secondary pollution. The existing solidification technology has problems such as exceeding the leaching rate and insufficient solidification body strength. For example, patent CN20XX123456A uses cement-based solidification, but the arsenic leaching rate is still 5.6mg / L, which cannot meet the requirements of GB5085.3 standard. Therefore, we propose a composite metal oxide solidifying agent and its application in sulfur-arsenic solidification and arsenic solidification harmless treatment of arsenic sulfide residue to solve the problems raised in the above background.

[0003] The above information disclosed in this background section is only for the purpose of increasing the understanding of the background of the present application and therefore can include matters known by those skilled in the art but not necessarily form the prior art that is already known. SUMMARY

[0004] The purpose of the present application is to provide a composite metal oxide solidifying agent and its application in sulfur-arsenic solidification and arsenic solidification harmless treatment of arsenic sulfide residue to solve the problems raised in the above background.

[0005] To achieve the above purpose, the present application provides the following technical solution: a composite metal oxide solidifying agent, comprising the following components: Fe2O330-45wt%, Al2O320-30wt%, CaO 15-25wt%, SiO25-10wt%, TiO21-3wt%, bentonite binder 3-5wt%, citric acid promoter 0.5-2wt%.

[0006] The present application also provides a preparation method of a composite metal oxide solidifying agent, comprising the following steps:

[0007] Step 1, raw material pretreatment: ball milling Fe2O3, Al2O3 and CaO in proportion, adding TiO2 nanoparticles, and ensuring uniformity by ultrasonic dispersion;

[0008] Step 2, sol-gel synthesis: adding deionized water to the mixture of step 1 and stirring to form a slurry;

[0009] Step 3, calcination treatment: calcining the slurry of step 2 at 550-650℃ for 2-3h to form a spinel structure;

[0010] Step 4, function enhancement: adding bentonite binder and citric acid promoter to the product of step 3 and performing secondary ball milling;

[0011] Step 5, forming package: the product of step 4 is spray-dried to powder, sieved and sealed for storage.

[0012] Preferably, in step 1, Fe2O3, Al2O3, CaO are ball-milled to D50≤5μm.

[0013] Preferably, in step 1, ultrasonic dispersion is performed for more than 30min.

[0014] Preferably, in step 2, stirring reaction is performed at 80℃ for 4h.

[0015] Preferably, in step 3, the calcination is performed by stepwise temperature increase, 10℃ / min before 200℃, and 5℃ / min after 200-500℃.

[0016] Preferably, in step 4, secondary ball-milling is performed to control the specific surface area to be≥200m 2 / kg.

[0017] Preferably, in step 5, the powder is sieved through a 200-mesh sieve.

[0018] The application also provides application of the above-mentioned composite metal oxide curing agent in harmless treatment of sulfurized arsenic residue.

[0019] Preferably, the application process of the composite metal oxide curing agent in harmless treatment of sulfurized arsenic residue is as follows: the curing agent and the sulfurized arsenic residue are mixed according to a mass ratio of 0.15-0.25:1, mixed in a double-shaft mixer at 15-20rpm for 15min, pressed into shape under a pressure of 5MPa, and cured at 25℃ and RH≥90% for 7 days, with the leaching arsenic≤0.3mg / L.

[0020] Compared with the prior art, the application has the following beneficial effects:

[0021] The application realizes lattice curing of arsenic by forming FeAl2O4 with spinel structure, promotes sulfate stabilization by calcium-sulfur synergistic effect, and reduces energy consumption by more than 30% through low-temperature calcination process.

[0022] The above summary is only for the purpose of the description and is not intended to limit in any way. In addition to the illustrative aspects, embodiments and features described above, further aspects, embodiments and features will be readily apparent to those skilled in the art by reference to the drawings and the following detailed description. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 The application is prepared according to the flowchart. DETAILED DESCRIPTION

[0024] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the protection scope of the present application.

[0025] Embodiment 1

[0026] The following components are prepared: Fe2O340wt%, Al2O325wt%, CaO 20wt%, SiO27wt%, TiO22wt%, bentonite binder 5wt%, citric acid promoter 1wt%.

[0027] Step 1, raw material pretreatment: mill Fe2O3, Al2O3, CaO in proportion to D50≤5μm, add TiO2 nanoparticles, and disperse by ultrasonic for more than 30min to ensure uniformity;

[0028] Step 2, sol-gel synthesis: add deionized water to the mixture of step 1 to form a slurry, and stir at 80℃ for 4h;

[0029] Step 3, calcination treatment: calcine the slurry of step 2 at 600℃ for 2h to form a spinel structure; use stepwise heating calcination, 10℃ / min before 200℃, 5℃ / min after 500℃;

[0030] Step 4, functional enhancement: add bentonite binder and citric acid promoter to the product of step 3 and perform secondary ball milling, control the specific surface area≥200m 2 / kg;

[0031] Step 5, molding and packaging: spray dry the product of step 4 to make powder, pass through a 200 mesh sieve, and seal and store.

[0032] Mix the curing agent and arsenic sulfide residue of the above embodiment 1 according to a mass ratio of 0.2:1, mix in a double shaft mixer at 20rpm for 15min, press into shape under a pressure of 5MPa, and maintain at 25℃ and RH≥90% constant temperature and humidity for 7 days to obtain a sample.

[0033] Embodiment 2

[0034] The following components are prepared: Fe2O335wt%, Al2O325wt%, CaO 23wt%, SiO29wt%, TiO23wt%, bentonite binder 3wt%, citric acid promoter 2wt%.

[0035] Step 1, raw material pretreatment: Fe2O3, Al2O3, CaO are ball milled to D50≤5μm in proportion, TiO2 nanoparticles are added, and ultrasonic dispersion is performed for more than 30 min to ensure uniformity;

[0036] Step 2, sol-gel synthesis: deionized water is added to the mixture of step 1 to form a slurry, and the slurry is stirred and reacted at 80℃ for 4h;

[0037] Step 3, calcination treatment: the slurry of step 2 is calcined at 550℃ for 2-3h to form a spinel structure; stepwise temperature rise calcination is adopted, 10℃ / min before 200℃, 5℃ / min after 450℃;

[0038] Step 4, functional enhancement: bentonite binder and citric acid accelerator are added to the product of step 3 and secondary ball milling is performed, and the specific surface area is controlled to be≥200m 2 / kg;

[0039] Step 5, molding and packaging: the product of step 4 is spray dried to powder, and then sealed and stored after passing through a 200 mesh screen.

[0040] The curing agent and arsenic sulfide residue of Example 2 above are mixed in a mass ratio of 0.2:1, mixed in a double-shaft mixer at 20rpm for 15min, pressed into shape under a pressure of 5MPa, and cured at 25℃, RH≥90% for 7 days to obtain a sample.

[0041] Example 3

[0042] The following components are prepared: Fe2O345wt%, Al2O320wt%, CaO 25wt%, SiO25wt%, TiO21wt%, bentonite binder 3.5wt%, citric acid accelerator 0.5wt%.

[0043] Step 1, raw material pretreatment: Fe2O3, Al2O3, CaO are ball milled to D50≤5μm in proportion, TiO2 nanoparticles are added, and ultrasonic dispersion is performed for more than 30 min to ensure uniformity;

[0044] Step 2, sol-gel synthesis: deionized water is added to the mixture of step 1 to form a slurry, and the slurry is stirred and reacted at 80℃ for 4h;

[0045] Step 3, calcination treatment: the slurry of step 2 is calcined at 650℃ for 2-3h to form a spinel structure; stepwise temperature rise calcination is adopted, 10℃ / min before 200℃, 5℃ / min after 550℃;

[0046] Step 4, functional enhancement: bentonite binder and citric acid accelerator are added to the product of step 3 and secondary ball milling is performed, and the specific surface area is controlled to be≥200m 2 / kg;

[0047] Step 5, molding and packaging: the product of step 4 is spray-dried into powder, and then sealed and stored after being passed through a 200-mesh sieve.

[0048] The curing agent and arsenic sulfide residue of the above example 3 were mixed according to a mass ratio of 0.2:1, mixed in a double-shaft mixer at 20 rpm for 15 min, pressed into shape under a pressure of 5 MPa, and cured at 25°C and RH≥90% for 7 days to obtain a sample.

[0049] Example 4

[0050] The following components were prepared: Fe2O330 wt%, Al2O330 wt%, CaO 20 wt%, SiO210 wt%, TiO23 wt%, bentonite binder 5 wt%, and citric acid accelerator 2 wt%.

[0051] Step 1, raw material pretreatment: Fe2O3, Al2O3, and CaO were ball-milled to D50≤5 μm according to the proportions, and TiO2 nanoparticles were added and uniformly dispersed by ultrasonic dispersion for more than 30 min;

[0052] Step 2, sol-gel synthesis: deionized water was added to the mixture of step 1 to form a slurry, and the slurry was stirred and reacted at 80°C for 4 h;

[0053] Step 3, calcination treatment: the slurry of step 2 was calcined at 580°C for 2-3 h to form a spinel structure; the calcination was performed by stepwise heating, at a rate of 10°C / min before 200°C and 5°C / min after 480°C;

[0054] Step 4, functional reinforcement: bentonite binder and citric acid accelerator were added to the product of step 3 and subjected to secondary ball milling, and the specific surface area was controlled to be≥200 m 2 / kg;

[0055] Step 5, molding and packaging: the product of step 4 was spray-dried into powder, and then sealed and stored after being passed through a 200-mesh sieve.

[0056] The curing agent and arsenic sulfide residue of the above example 4 were mixed according to a mass ratio of 0.2:1, mixed in a double-shaft mixer at 20 rpm for 15 min, pressed into shape under a pressure of 5 MPa, and cured at 25°C and RH≥90% for 7 days to obtain a sample.

[0057] Comparative example 1: traditional cement-based curing agent

[0058] The curing agent and arsenic sulfide residue of the above comparative example 1 were mixed according to a mass ratio of 0.2:1, mixed in a double-shaft mixer at 20 rpm for 15 min, pressed into shape under a pressure of 5 MPa, and cured at 25°C and RH≥90% for 7 days to obtain a sample.

[0059] I. Comparative Experiment

[0060] 1. Arsenic leaching performance test according to GB / T 36600-2018 standard. The results are shown in Table 1 below.

[0061] Table 1. Arsenic leaching performance test results

[0062] Group Leaching arsenic concentration (mg / L) Leaching rate reduction rate (vs. original residue) Compressive strength (MPa) 7-day maintenance compliance rate Example 1 0.18 97.2％ 12.5 100％ Example 2 0.23 95.1％ 10.8 95％ Example 3 0.21 96.3％ 9.5 90％ Example 4 0.27 94.4％ 8.2 85％ Comparative Example 1 5.6 - 3.8 60％

[0063] As can be seen from the above, the arsenic leaching amount of Examples 1-4 is ≤0.3 mg / L, all of which meet the standard limit value of 2.0 mg / L of GB / T 36600, and the arsenic leaching amount of Example 1 is the lowest at 0.18 mg / L, and the compressive strength is also better than that of other groups.

[0064] 2. Heavy metal form analysis by BCR sequential extraction method. The results are shown in Table 2 below.

[0065] Table 2. Heavy metal form analysis results

[0066] Group Residual state (%) Iron-manganese oxide state (%) Organically bound state (%) Exchangeable state (%) Example 1 78.3 15.6 4.2 1.9 Example 2 72.1 20.3 5.1 2.5 Example 3 73.6 19.6 4.5 2.3 Example 4 76.9 16.2 4.8 2.1 Comparative Example 1 45.7 32.8 12.6 9.9

[0067] As can be seen from the above, Example 1 converts 97.1% of arsenic in arsenic sulfide residue into stable state, i.e. residual state + iron and manganese oxide state, and the exchangeable arsenic is reduced to 1.9%.

[0068] 3. Thermal stability test by TG-DSC analysis method. The results are shown in Table 3 below.

[0069] Table 3. Thermal stability test results

[0070]

[0071]

[0072] As can be seen from the above, the mass loss rate of Examples 1-4 is ≤2.3%, and the mass loss rate of Example 1 sample at high temperature is only 1.8%, which is better than 4.7% of Comparative Example 1, and the thermal stability is good.

[0073] II. Toxicology Evaluation

[0074] 1. Acute toxicity test

[0075] Kunming mice with a body weight of 18-25 g were selected for acute toxicity test. The administration routes included oral, transdermal and inhalation, and the fixed dose method was used for grouping experiment, and the dose groups were 5, 50, 300, 2000, 5000 mg / kg. The animal behavior, poisoning symptoms and death were observed continuously within 14 days after exposure. The results are shown in Table 4 below.

[0076] Table 4. Acute toxicity test results

[0077] Group Rat oral LD 50 (mg / kg) Skin contact LD 50 (mg / kg) Inhalation LC 50 (mg / m 3 )]]> Example 1 >5000 >2000 >50 Comparative Example 1 860 1200 15

[0078] From the above, the sample of Example 1 has no acute toxicity, LD 50 >5000mg / kg, safety is significantly better than Comparative Example 1.

[0079] 2. Chronic toxicity test

[0080] SD rats were selected for 90-day feeding test, the dose was 10%-25% of the maximum no-effect dose. The administration method was mixed feeding, once a day, and the animal growth, behavior and physiological changes were observed continuously. The absolute / relative weight changes of liver and kidney, blood biochemical indicators ALT and histopathological changes were recorded. The results are shown in Table 5 below.

[0081] Table 5. Results of chronic toxicity test

[0082] Group Liver coefficient (%) Kidney coefficient (%) Serum ALT (U / L) Histopathological changes Example 1 3.2±0.2 0.9±0.1 35±5 No abnormalities Comparative Example 1 4.1±0.3 1.2±0.2 68±8 Hepatocyte steatosis, renal tubular damage

[0083] From the above, long-term exposure to the sample of Example 1 has no cumulative effect of chronic toxicity.

[0084] III. Environmental safety verification

[0085] 1. Terrestrial plant toxicity test

[0086] Wheat or Chinese cabbage seeds were cultured in soil containing 25% of the sample of Example 1 and Comparative Example 1, and the germination rate was counted to evaluate its effect on seed germination. The root length, plant height and biomass were measured to evaluate its effect on seedling growth. The results are shown in Table 6 below.

[0087] Table 6. Results of terrestrial plant toxicity test

[0088] Group Germination rate (%) Biomass inhibition rate (%) Example 1 >91 <8 Comparative Example 1 <60 >25

[0089] From the above, the germination rate of Example 1 is >91%, and the biomass inhibition rate is <8%, indicating that the sample of Example 1 is relatively safe, has no toxic effect on seed germination and seedling growth, and has very low ecological risk.

[0090] 2. Earthworm toxicity test

[0091] Eisenia foetida was exposed to the sample of Example 1 and Comparative Example 1 for 14 days, and the survival rate was observed. The reproductive ability was evaluated after 56 days of exposure. The results are shown in Table 7 below.

[0092] Table 7. Results of earthworm toxicity test

[0093] Group Survival rate (%) Reproduction inhibition rate (%) Example 1 >92 <10 Comparative Example 1 <63 >35

[0094] As can be seen from the above, the germination rate of Example 1 is >92%, and the biomass inhibition rate is <10%, indicating that the sample of Example 1 is relatively safe, does not have toxic effects on earthworms, and has extremely low ecological risk.

[0095] In the description of the present specification, the description of the terms "one embodiment", "some embodiments", "an example", "a specific example" or "some examples" and the like means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In the present specification, the illustrative description of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any appropriate manner in any one or more embodiments or examples. Furthermore, different embodiments or examples described in the present specification and the features of different embodiments or examples can be combined and combined by those skilled in the art without contradiction.

[0096] Although the embodiments of the present application have been shown and described above, it is understood that the above-described embodiments are exemplary and are not to be construed as limiting the present application, and those skilled in the art can make changes, modifications, replacements and variations to the above-described embodiments within the scope of the present application.

Claims

1. A composite metal oxide curing agent, characterized by, The composite metal oxide curing agent comprises the following components: Fe2O330-45wt%, Al2O320-30wt%, CaO 15-25wt%, SiO25-10wt%, TiO21-3wt%, bentonite binder 3-5wt%, citric acid promoter 0.5-2wt%.

2. The method of claim 1, wherein the composite metal oxide curing agent is prepared by the steps of: The method comprises the following steps: ​ Step 1, raw material pretreatment: Fe2O3, Al2O3 and CaO are ball milled in proportion, and TiO2 nanoparticles are added to ensure uniformity by ultrasonic dispersion; Step 2, sol-gel synthesis: deionized water is added to the mixture of step 1 and stirred to form a slurry; Step 3, calcination treatment: the slurry of step 2 is calcined at 550-650℃ for 2-3h to form a spinel structure; Step 4, functional enhancement: bentonite binder and citric acid promoter are added to the product of step 3 and secondary ball milling is performed; Step 5, molding and packaging: the product of step 4 is spray dried to powder, sieved and then sealed and stored.

3. The preparation method of the composite metal oxide curing agent according to claim 2, characterized in that: In the step 1, Fe2O3, Al2O3 and CaO are ball milled to D50≤5μm.

4. The preparation method of the composite metal oxide curing agent according to claim 2, characterized in that: In the step 1, ultrasonic dispersion is performed for more than 30min.

5. The preparation method of a composite metal oxide curing agent according to claim 2, characterized in that: In the step 2, stirring is performed at 80℃ for 4h.

6. The preparation method of a composite metal oxide curing agent according to claim 2, characterized in that: In the step 3, stepwise temperature rising calcination is adopted, 10℃ / min before 200℃, and 5℃ / min after 200-500℃.

7. The preparation method of a composite metal oxide curing agent according to claim 2, characterized in that: In step 4, the secondary ball milling controls the specific surface area to be > 200 m 2 / kg.

8. The method of claim 2, wherein the composite metal oxide curing agent is prepared by the steps of: In the step 5, the powder is sieved through a 200 mesh sieve. ​ 9. The application of the composite metal oxide curing agent in the harmless treatment of sulfurized arsenic slag for sulfur fixation and arsenic fixation.

10. The use of the composite metal oxide curing agent according to claim 9 in the harmless treatment of sulfurized arsenic residue for sulfur fixation and arsenic fixation, characterized in that, The application process of the composite metal oxide curing agent in the harmless treatment of sulfurized arsenic slag for sulfur fixation and arsenic fixation is as follows: the curing agent and sulfurized arsenic slag are mixed in a mass ratio of 0.15-0.25:1, mixed in a double-shaft mixer at 15-20rpm for 15min, pressed into shape under a pressure of 5MPa, and cured at 25℃ and RH≥90% for 7 days, with the leaching arsenic being ≤0.3mg / L.

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