Phosphoaluminate cementitious material for hazardous waste solidification, and preparation method and application thereof, and hazardous waste utilization mortar

Abstract

The application discloses a kind of phosphoaluminate cementing materials for hazardous waste solidification and its preparation method and application and hazardous waste utilization mortar;The phosphoaluminate cementing material for hazardous waste solidification comprises: phosphoaluminate cementing material, bentonite, heavy metal chelating agent, activated carbon, and the weight ratio of the phosphoaluminate cementing material, bentonite, heavy metal chelating agent, activated carbon is 60-100:10-40:0-5:1-10;Wherein, the phosphoaluminate cementing material is formed by wet raw material calcination, and the powdered material in the wet raw material comprises: limestone, bauxite, apatite;The phosphoaluminate cementing material for hazardous waste solidification has the ability to adsorb heavy metal ions in solution, and can be used to solidify heavy metals in hazardous waste materials such as fly ash, effectively eliminate the pollution generated by hazardous waste disposal, and realize the harmless, reduction and resource treatment of hazardous waste.

Description

TECHNICAL FIELD

[0001] The present application relates to a phosphate-aluminate cementitious material, in particular, to a phosphate-aluminate cementitious material for hazardous waste solidification and a preparation method and application thereof and a hazardous waste utilization mortar. BACKGROUND

[0002] With the development of modern industry, the amount of waste is increasing year by year, and the problems of environmental protection, resources and sustainable development are becoming increasingly prominent, and the harm to the human environment is becoming more and more serious. Especially with the development of modern electronic information technology, pharmaceutical and chemical technology, many solid waste hazardous waste are generated. How to effectively recycle and utilize these solid waste to pollute the environment is not only a world problem, but also a new topic for China's renewable resource recycling. Whether it is an industrialized country or a developing country, it is facing the problem of hazardous waste disposal. SUMMARY

[0003] The purpose of the present application is to provide a phosphate-aluminate cementitious material for hazardous waste solidification and a preparation method and application thereof and a hazardous waste utilization mortar; the phosphate-aluminate cementitious material for hazardous waste solidification has the ability to adsorb heavy metal ions in solution, and can be used to solidify heavy metals in fly ash and other hazardous waste materials, effectively eliminating the pollution generated by hazardous waste disposal, and realizing the harmless, reduction and resource treatment of hazardous waste.

[0004] In order to achieve the above purpose, the present application provides a phosphate-aluminate cementitious material for hazardous waste solidification, comprising: a phosphate-aluminate cementitious material, bentonite, a heavy metal chelating agent, activated carbon, and the weight ratio of the phosphate-aluminate cementitious material, bentonite, heavy metal chelating agent and activated carbon is 60-100:10-40:0-5:1-10; wherein the phosphate-aluminate cementitious material is obtained by calcining wet raw materials, and the powdered material in the wet raw materials comprises limestone, bauxite and apatite.

[0005] The present application also provides a preparation method of the phosphate-aluminate cementitious material for hazardous waste solidification as described above, the preparation method comprising:

[0006] 1) crushing limestone, bauxite and apatite, then grinding and sieving to obtain powdered material, then mixing the powdered material and water to obtain wet raw materials, and then calcining the wet raw materials to obtain a phosphate-aluminate cementitious material;

[0007] 2) mixing the phosphate-aluminate cementitious material, bentonite, heavy metal chelating agent and activated carbon to obtain the phosphate-aluminate cementitious material for hazardous waste solidification.

[0008] The present application further provides a hazardous waste utilization mortar, which comprises fly ash and the phosphate-aluminate cementitious material for hazardous waste solidification as described above, and the weight ratio of fly ash and the phosphate-aluminate cementitious material for hazardous waste solidification is 1:0.8-1.2.

[0009] The application further provides application of the phosphoaluminate cementing material for solidifying hazardous waste in solidifying metal ions.

[0010] In the technical scheme, the bentonite: the montmorillonite in the bentonite is a hydrous layered silicate mineral, and the cation between the layers has exchangeability, can produce adsorption on the heavy metal ions; the heavy metal chelating agent: chelates the heavy metal ions, produces a hydrophobic structure to precipitate, and under the action of the macromolecule structure, the precipitation and removal rate is significantly improved through flocculation and net trapping; the activated carbon: a porous material, has a high pore structure, a large surface area, can contact the heavy metal ions, and produces adsorption; the phosphoaluminate cementing material: has a fast hydration speed, can rapidly produce strength, and the strength is higher than that of the portland cement, and the phosphoaluminate has good adsorption on the heavy metal ions.

[0011] Under the joint action of the phosphoaluminate cementing material, the bentonite, the heavy metal chelating agent and the activated carbon, the phosphoaluminate cementing material for solidifying hazardous waste has the ability of adsorbing the heavy metal ions in the solution, can be used for solidifying the heavy metals in the fly ash and other hazardous waste materials, effectively eliminates the pollution generated in the disposal of hazardous waste, realizes the harmless, reduction and resource of the hazardous waste, and has important practical value. The phosphoaluminate cementing material for solidifying hazardous waste prepared by the method can effectively solidify the heavy metal ions in the fly ash, can obtain certain strength, the preparation method is simple, and therefore has wide market prospects.

[0012] Compared with similar products and processes, the application has the following main advantages:

[0013] 1. The phosphoaluminate cementing material for solidifying hazardous waste prepared by the application can effectively solidify the heavy metal ions leached from the fly ash.

[0014] 2. The phosphoaluminate cementing material for solidifying hazardous waste prepared by the application can produce ideal strength, and can be made into building material products such as bricks after solidifying the fly ash.

[0015] 3. The phosphoaluminate cementing material for solidifying hazardous waste prepared by the application can be made into a container for storing industrial wastewater and other solutions.

[0016] Other features and advantages of the application will be described in detail in the following specific embodiments. BRIEF DESCRIPTION OF DRAWINGS

[0017] The accompanying drawings are included to provide a further understanding of the application, and constitute a part of the specification, and together with the following specific embodiments, serve to explain the application, but do not constitute a limitation on the application. In the drawings:

[0018] Figure 1is a cylindrical container made of the cementitious material for hazardous waste solidification prepared by the present application

[0019] Figure 2 is Figure 1 a perspective view from another angle. DETAILED DESCRIPTION

[0020] The specific embodiments of the present application are described in detail below. It should be understood that the specific embodiments described herein are merely illustrative and explanatory of the present application and are not intended to limit the present application.

[0021] The present application provides a phosphoaluminate cementitious material for hazardous waste solidification, comprising: a phosphoaluminate cementitious material, bentonite, a heavy metal chelating agent, activated carbon, and the weight ratio of the phosphoaluminate cementitious material, bentonite, heavy metal chelating agent, and activated carbon is 60-100:10-40:0-5:1-10; preferably, the weight ratio of the phosphoaluminate cementitious material, bentonite, heavy metal chelating agent, and activated carbon is 60-80:20-30:1-2:2-5; wherein the phosphoaluminate cementitious material is obtained by wet raw material calcination, and the powdered material in the wet raw material comprises: limestone, bauxite, and apatite.

[0022] In the present application, the amount of limestone, bauxite, and apatite in the wet raw material can be selected within a wide range, but in order to further improve the solidification rate of the phosphoaluminate cementitious material for hazardous waste solidification to heavy metal ions and the strength after molding, preferably, the weight ratio of the limestone, bauxite, and apatite in the wet raw material is 30-70:30-60:5-20; more preferably, the weight ratio of the limestone, bauxite, and apatite is 40-45:40-45:15-20.

[0023] In the present application, the amount of each raw material in the wet raw material can be selected within a wide range, but in order to further improve the solidification rate of the phosphoaluminate cementitious material for hazardous waste solidification to heavy metal ions and the strength after molding, preferably, the weight ratio of the powdered material to water in the wet raw material is 100:10-20.

[0024] In the present application, the particle size of the powdered material can be selected within a wide range, but in order to further improve the solidification rate of the phosphoaluminate cementitious material for hazardous waste solidification to heavy metal ions and the strength after molding, preferably, the particle size of the powdered material is not greater than 80 μm.

[0025] In the present application, in order to further improve the solidification rate of the phosphoaluminate cementitious material for hazardous waste solidification to heavy metal ions and the strength after molding, preferably, the wet raw material is pretreated before calcination, including: pressing the wet raw material.

[0026] In the above embodiment, in order to further improve the pressing effect, preferably, the pressure of the pressing is 20-40 MPa.

[0027] In the present application, the conditions of the calcination can be selected in a wide range, but in order to further improve the solidification rate of the heavy metal ions by the phosphoaluminate cementitious material for hazardous waste solidification and the strength after molding, preferably, the calcination at least satisfies the following conditions: heating from 15-35℃ to 1300-1500℃ at a heating rate of 5-10℃ / min, and holding for 1-3h.

[0028] In the present application, in order to further improve the solidification rate of the heavy metal ions by the phosphoaluminate cementitious material for hazardous waste solidification and the strength after molding, preferably, the wet raw material is subjected to post-treatment after the calcination, including: spraying the calcination product with water, and turning over for 1-2min, after the spraying is completed, spreading the material, and using the residual heat to naturally dry the material.

[0029] In the present application, the type of the bentonite can be selected in a wide range, but in order to further improve the solidification rate of the heavy metal ions by the phosphoaluminate cementitious material for hazardous waste solidification and the strength after molding, preferably, the bentonite is selected from at least one of sodium-based bentonite and microwave-activated bentonite.

[0030] In the present application, the type of the microwave-activated bentonite can be selected in a wide range, but in order to further improve the solidification rate of the heavy metal ions by the phosphoaluminate cementitious material for hazardous waste solidification and the strength after molding, preferably, the microwave-activated bentonite is obtained by microwave-activating natural bentonite, wherein the frequency of the microwave activation is 1000-5000MHz, and the activation time is 5-20min.

[0031] In the present application, the heavy metal chelating agent can be selected in a wide range, but in order to further improve the solidification rate of the heavy metal ions by the phosphoaluminate cementitious material for hazardous waste solidification and the strength after molding, preferably, the heavy metal chelating agent is at least one of EDTA compounds (ethylenediaminetetraacetic acid compounds) or DTC compounds (dithiocarbamate compounds).

[0032] In the present application, the particle size of the bentonite and the activated carbon can be selected in a wide range, but in order to further improve the solidification rate of the heavy metal ions by the phosphoaluminate cementitious material for hazardous waste solidification and the strength after molding, preferably, the average particle size of the bentonite is 45-150μm, and the average particle size of the activated carbon is 10-100μm.

[0033] The present application also provides a preparation method of the phosphoaluminate cementitious material for hazardous waste solidification as described above, and the preparation method comprises:

[0034] 1) crushing limestone, bauxite and apatite, then grinding and sieving to obtain powdery materials, then mixing the powdery materials with water to obtain wet raw materials, and then calcining the wet raw materials to obtain a phosphoaluminate cementitious material;

[0035] 2) mixing the phosphoaluminate cementitious material, bentonite, heavy metal chelating agent, and activated carbon to obtain the phosphoaluminate cementitious material for hazardous waste solidification.

[0036] The application further provides a hazardous waste utilization mortar, which comprises hazardous waste solids and the phosphoaluminate cementitious material for hazardous waste solidification as described above, and the weight ratio of the hazardous waste solids to the phosphoaluminate cementitious material is 1:0.8-1.2.

[0037] In the above embodiment, in order to further improve the strength of the prepared hazardous waste utilization mortar after curing and molding, preferably, the hazardous waste utilization mortar at least meets the following conditions: the water-binder ratio is 0.4-0.7, the mortar-binder ratio is 1:2-5, and the curing time is more than 28 days.

[0038] In the above embodiment, the type of the hazardous waste solids can be selected in a wide range, and preferably, the hazardous waste solids are fly ash, considering the difficulty in obtaining raw materials and the price.

[0039] The application further provides an application of the phosphoaluminate cementitious material for hazardous waste solidification as described above in solidifying metal ions.

[0040] In the above application, the specific application mode can be various, but preferably, in the application, the phosphoaluminate cementitious material for hazardous waste solidification is mixed with water, and then a container is prepared; then a heavy metal solution is placed in the container for standing; wherein, during the standing process, the container is cured in water, and the liquid level inside and outside the container is the same; thus, the heavy metal in the solution can be solidified by the container.

[0041] In the above embodiment, the water-binder ratio of the phosphoaluminate cementitious material for hazardous waste solidification mixed with water can be varied in a wide range, but preferably, the water-binder ratio of the phosphoaluminate cementitious material for hazardous waste solidification mixed with water is 0.25-0.35, in order to further improve the strength of the container after curing and molding.

[0042] In the above embodiment, the curing time can be varied in a wide range, but preferably, the curing time is more than 28 days, in order to further improve the strength of the container after curing and molding.

[0043] The present application will be described in detail below by examples. In the following examples, the average particle size of bentonite is 100 μm, and the average particle size of activated carbon is 60 μm. During sieving, if the sieve residue is not less than 1.2 wt%, the grinding is repeated for several times; the microwave-activated bentonite is obtained by microwave-activating natural bentonite, wherein the frequency of microwave activation is 3000 MHz, and the activation time is 10 min.

[0044] Example 1

[0045] Step one, the raw materials are weighed according to the mass percentage of 45% limestone, 40% bauxite and 15% apatite. The raw materials are crushed to particles less than 5 mm, and then ground in a ball mill. The ground powder is sieved through a 80 μm sieve with a sieve residue of less than 1.2 wt%. Distilled water is added to the ground powder at a rate of 15% of the total mass of the powder. 100 g of wet raw material is stirred uniformly each time, and then pressed into a round cake under a pressure of 30 MPa using a 70 mm circular mold. The round cake is placed in a muffle furnace and heated at a rate of 6 ℃ / min from 25 ℃ to 1400 ℃, and then kept for 2 h. After the calcination is completed, the material is removed and sprayed with a spray bottle filled with pure water. The material is turned over with a shovel for 1 min. After the spraying is completed, the material is spread out and allowed to dry naturally using the residual heat. A phosphate aluminate cementitious material is prepared.

[0046] Step two, the phosphate aluminate cementitious material, bentonite (sodium-based bentonite), heavy metal chelating agent (EDTA) and activated carbon are mixed according to the mass percentage of 70%, 26%, 1% and 3% respectively, and then ground in a ball mill. The ground powder is sieved through a 80 μm sieve with a sieve residue of less than 1.2 wt%. A phosphate aluminate cementitious material for hazardous waste solidification is prepared.

[0047] Step three, the phosphate aluminate cementitious material for hazardous waste solidification is mixed with fly ash at a weight ratio of 1:1 to form a cement mortar. The water-binder ratio is 0.5, and the binder-sand ratio is 1:3. The mortar is cured for 28 d, and then the mortar strength and heavy metal ion leaching concentration are detected to calculate the solidification rate.

[0048] Step four, a phosphate aluminate cementitious material for hazardous waste solidification is prepared to have a neat paste with a water-binder ratio of 0.28. A cylindrical container is prepared with an outer diameter of 100 mm, a height of 50 mm, and an inner diameter of 80 mm. A heavy metal ion solution (one of Cr, Ni, Pb, Zn, Cd and Cu ion solutions) with an ion concentration of 10 mg / L is prepared. The solution is poured into the cylindrical container to a height of 2 / 3 of the container. The cylindrical container containing the solution is placed in a plastic box, and deionized water is added to the plastic box until the inner and outer liquid levels are consistent, as shown in FIG. 1. The plastic box is sealed with a plastic film, as shown in FIG. 2. After curing for 28 d, the inner and outer solutions are drawn, and the ion concentration is detected to calculate the solidification rate. Figure 1 Figure 2 Figure 1 and​​Figure 2 The purpose of the apparatus shown is to inject a solution of a certain ion concentration into a container, cure it for a certain period of time, and then detect the ion concentration inside and outside the container. The main purpose is to establish a detection method to evaluate the ability of different cementitious materials to solidify heavy metal ions.

[0049] Example 2

[0050] Step 1: Weigh the raw materials according to the mass percentages of limestone (40%), bauxite (40%), and apatite (20%). Crush the raw materials to particles smaller than 5mm, grind them in a ball mill, and pass them through an 80μm sieve with a residue of less than 1.2wt%. Add 15% distilled water (based on the total mass of the powdered raw materials) to the ground powder and stir well. Weigh 100g of wet raw material each time and press it into round cakes using a 70mm circular mold under a pressure of 30MPa. Place the round cakes in a muffle furnace and heat them from 25℃ to 1380℃ at a heating rate of 6℃ / min, holding for 2 hours. After calcination, remove the material and spray it with a spray bottle filled with pure water, turning it over with an iron shovel for 1 minute. After spraying, spread the material out and allow it to air dry naturally using residual heat to obtain the phosphoaluminate cementitious material.

[0051] Step 2: Mix 65% phosphoaluminate cementitious material, 28% bentonite (microwave activated bentonite), 2% heavy metal chelating agent (DTC) and 5% activated carbon by mass percentage, place them in a ball mill and grind them until the residue on an 80μm sieve is less than 1.2wt%, and prepare phosphoaluminate cementitious material for hazardous waste solidification.

[0052] Step 3: Prepare the phosphoaluminate cementitious material for hazardous waste solidification by mixing it with fly ash at a 1:1 weight ratio and then forming it into cement mortar. The water-cement ratio is 0.5, and the mortar-cement ratio is 1:3. After curing for 28 days, test the mortar strength and the leaching concentration of heavy metal ions, and calculate the curing rate.

[0053] Step 4: The phosphoaluminate cementitious material for hazardous waste solidification prepared in Step 2 above yields a clean slurry with a water-to-cement ratio of 0.28. This slurry is then fabricated into a cylindrical container with an outer diameter of 100 mm, a height of 50 mm, and an inner diameter of 80 mm. A heavy metal ion solution (one of Cr, Ni, Pb, Zn, Cd, or Cu ions) with an ion concentration of 10 mg / L is prepared. The solution is poured into the cylindrical container, filling it to 2 / 3 full. The cylindrical container containing the solution is placed in a plastic box, and deionized water is added to the plastic box until the internal and external liquid levels are consistent. The plastic box is then sealed with plastic film and cured for 28 days. After curing, the internal and external solutions are sampled, the ion concentration is measured, and the solidification rate is calculated.

[0054] Example 3

[0055] Step one, according to the mass percentage of 40% limestone, 42% bauxite, 18% apatite, the raw materials are weighed. The raw materials are crushed to less than 5mm particles, placed in a ball mill for grinding, and passed through an 80μm sieve with a residue of less than 1.2wt%. Add 15% of the total mass of the powdered raw material to the ground powder, stir evenly, take 100g of wet raw material each time, use a 70mm circular mold, and press into a round cake material under a pressure of 30MPa. The round cake material is placed in a muffle furnace, heated at a rate of 6℃ / min from 25℃ to 1380℃, and held for 2h. After calcination, the material is removed, sprayed with a spray bottle filled with pure water, and the material is turned over with a shovel. The whole process lasts 1min. After spraying, spread the material and use the residual heat to dry the material naturally. A phosphoaluminate cementitious material is prepared.

[0056] Step two, mix the phosphoaluminate cementitious material 75%, bentonite 22% (sodium-based bentonite), heavy metal chelating agent 1% (EDTA), and activated carbon 2% according to the mass percentage, place in a ball mill for grinding, pass through an 80μm sieve, and the residue is less than 1.2wt%. A phosphoaluminate cementitious material for hazardous waste solidification is prepared.

[0057] Step three, mix the phosphoaluminate cementitious material for hazardous waste solidification with fly ash at a weight ratio of 1:1 to form a cement mortar. The water-binder ratio is 0.5, the binder-sand ratio is 1:3, the mortar strength and heavy metal ion leaching concentration are detected after 28d of curing, and the solidification rate is calculated.

[0058] Step four, prepare a net paste with a water-binder ratio of 0.28 from the phosphoaluminate cementitious material for hazardous waste solidification, into a cylindrical container with an outer diameter of 100mm, a height of 50mm, and an inner diameter of 80mm. Prepare a heavy metal ion solution with an ion concentration of 10mg / L (one of Cr, Ni, Pb, Zn, Cd, Cu ion solutions). Pour the solution into the cylindrical container to 2 / 3 of the height. Place the cylindrical container containing the solution into a plastic box, add deionized water to the plastic box until the inner and outer liquid levels are consistent. Cover the plastic box with plastic film to seal it. After 28d of curing, the inner and outer solutions are drawn, the ion concentration is detected, and the solidification rate is calculated.

[0059] Comparative Example 1

[0060] Step one, select silicate cement (PII 52.5) 75%, bentonite 22% (sodium-based bentonite), heavy metal chelating agent 1% (EDTA), and activated carbon 2% by mass percentage, mix to prepare a cementitious material, and mix with fly ash at a weight ratio of 1:1 to form a cement mortar. The water-binder ratio is 0.5, the binder-sand ratio is 1:3, the mortar strength and heavy metal ion leaching concentration are detected after 28d of curing, and the solidification rate is calculated.

[0061] Step two, select Portland cement (PII 42.5) 75%, bentonite 22% (sodium-based bentonite), heavy metal chelating agent 1% (EDTA) and activated carbon 2% of the mass percentage mixed, made of cementitious materials, made into a container of neat paste with a water-cement ratio of 0.28, then made into a cylindrical container, container outer diameter 100 mm, high 50 mm, inner diameter 80 mm, prepared ion concentration in 10 mg / L heavy metal ion solution (one of Cr, Ni, Pb, Zn, Cd, Cu ion solution). Pour the solution into the cylindrical container, pour to 2 / 3 height. The cylindrical container containing the solution is placed in a plastic box, and deionized water is added in the plastic box until the inner and outer liquid levels are consistent. Cover the plastic box with plastic film to seal, and after 28 days of curing, draw the inner and outer solutions, detect ion concentration, and calculate solidification rate.

[0062] Comparative Example 2

[0063] Step one, select ordinary Portland cement (PO 42.5) 75%, bentonite 22% (sodium-based bentonite), heavy metal chelating agent 1% (EDTA) and activated carbon 2% of the mass percentage mixed, prepared cementitious materials, mixed with fly ash according to the weight ratio of 1:1, then formed cement mortar. The water-cement ratio is 0.5, the cement-sand ratio is 1:3, and the strength and heavy metal ion leaching concentration of the cement mortar are detected after 28 days of curing to calculate the solidification rate.

[0064] Step two, select ordinary Portland cement (PO 42.5) 75%, bentonite 22% (sodium-based bentonite), heavy metal chelating agent 1% (EDTA) and activated carbon 2% of the mass percentage mixed, made of cementitious materials, formed into a container of neat paste with a water-cement ratio of 0.28, then made into a container container, container outer diameter 100 mm, high 50 mm, inner diameter 80 mm, prepared ion concentration in 10 mg / L heavy metal ion solution. Pour the solution into the cylindrical container, pour to 2 / 3 height. The cylindrical container containing the solution is placed in a plastic box, and deionized water is added in the plastic box until the inner and outer liquid levels are consistent. Cover the plastic box with plastic film to seal, and after 28 days of curing, draw the inner and outer solutions, detect ion concentration, and calculate solidification rate.

[0065] Comparative Example 3

[0066] Step one, select masonry cement (M32.5) 75%, bentonite 22% (sodium-based bentonite), heavy metal chelating agent 1% (EDTA) and activated carbon 2% of the mass percentage mixed, prepared cementitious materials, mixed with fly ash according to the weight ratio of 1:1, then formed cement mortar. The water-cement ratio is 0.5, the cement-sand ratio is 1:3, and the strength and heavy metal ion leaching concentration of the cement mortar are detected after 28 days of curing.

[0067] Step two, select the masonry cement (M32.5) 75%, bentonite 22% (sodium bentonite), heavy metal chelating agent 1% (EDTA) and activated carbon 2% of the mass percentage mixed, made of cementitious materials, the water cement ratio of 0.28 of the neat paste, then made into a cylindrical container, container outer diameter 100 mm, high 50 mm, preparation of ion concentration in 10 mg / L heavy metal ion solution (Cr, Ni, Pb, Zn, Cd, Cu solution). Pour the solution into the cylindrical container, pour 2 / 3 height. The cylindrical container containing the solution is placed into a plastic box, add deionized water to the plastic box to keep the liquid level consistent. Cover the plastic box with plastic film to seal, after 28 d curing, the internal and external solution is extracted, the ion concentration is detected.

[0068] Comparative example 4

[0069] According to the method of example 1, the only difference is that in step one, the raw materials are weighed according to the mass percentage of 20% bauxite, 80% limestone.

[0070] Comparative example 5

[0071] According to the method of example 1, the only difference is that in step one, the raw materials are weighed according to the mass percentage of 50% bauxite, 50% limestone.

[0072] Comparative example 6

[0073] According to the method of example 1, the only difference is that in step one, the raw materials are weighed according to the mass percentage of 73% limestone, 25% bauxite, 2% apatite.

[0074] Comparative example 7

[0075] According to the method of example 1, the only difference is that in step two, the mass percentage of 97% of the phosphate aluminate cementitious material, 1% of the heavy metal chelating agent (EDTA) and 2% of the activated carbon is mixed.

[0076] Comparative example 8

[0077] According to the method of example 1, the only difference is that in step two, the mass percentage of 75% of the phosphate aluminate cementitious material, 22% of the bentonite (sodium bentonite) and 3% of the activated carbon is mixed.

[0078] Comparative example 9

[0079] According to the method of example 1, the only difference is that in step two, the mass percentage of 75% of the phosphate aluminate cementitious material, 22% of the bentonite (sodium bentonite), 3% of the heavy metal chelating agent (EDTA) is mixed.

[0080] Test example 1

[0081] 1) The solidification effect on fly ash is shown in Table 1;

[0082] 2) The solidification effect on heavy metal ion solution is shown in Table 2;

[0083] In Table 1 and Table 2, the heavy metal ion solidification rate (%) is detected by the inductively coupled ion emission spectrometry method for the determination of 32 elements of water quality HJ 776-2015 method, and the calculation formula is The compressive strength is detected by the method of "Cement mortar strength test method (ISO) method" GB / T 17671-2021.

[0084] Table 1 Solidification effect on fly ash

[0085]

[0086]

[0087] Table 2 Solidification effect on heavy metal ion solution

[0088]

[0089] From Table 1 and Table 2, it can be seen that:

[0090] The comparison between Comparative Example 1 and Example 1 shows that: Portland cement (PII 52.5) as cementitious material, compared with the cementitious material prepared in Example 1, its adsorption capacity for heavy metal ions in solution and fly ash is weaker, and the mortar strength is lower than that of the cementitious material prepared in Example 1.

[0091] The comparison between Comparative Example 2 and Example 1 shows that: ordinary Portland cement (PO 42.5) as cementitious material, compared with the cementitious material prepared in Example 1, its adsorption capacity for heavy metal ions in solution and fly ash is weaker, and the mortar strength is lower than that of the cementitious material prepared in Example 1.

[0092] The comparison between Comparative Example 3 and Example 1 shows that: masonry cement (M 32.5) as cementitious material, compared with the cementitious material prepared in Example 1, its adsorption capacity for heavy metal ions in solution and fly ash is weaker, and the mortar strength is lower than that of the cementitious material prepared in Example 1.

[0093] The comparison between Comparative Example 4 and Example 1 shows that: in the batching of the cementitious material, if there is no apatite, the main mineral after calcination is calcium aluminate, and compared with the cementitious material prepared in Example 1, its adsorption capacity for heavy metal ions in solution and fly ash is weaker, and the mortar strength is lower than that of the cementitious material prepared in Example 1.

[0094] Comparative Example 5 and Example 1 can be compared: if there is no apatite in the batching of the cementing material, the main minerals after calcination are calcium aluminate and calcium dialuminate, and the cementing material prepared in Example 1 has weaker adsorption capacity for heavy metal ions in solution and heavy metal ions in fly ash, and the mortar strength is lower than that of the cementing material prepared in Example 1.

[0095] Comparative Example 6 and Example 1 can be compared: if the content of apatite in the batching of the cementing material is low, the content of calcium phosphoaluminate in the minerals after calcination is low, and the cementing material prepared in Example 1 has weaker adsorption capacity for heavy metal ions in solution and heavy metal ions in fly ash, and the mortar strength is lower than that of the cementing material prepared in Example 1.

[0096] Comparative Example 7 and Example 1 can be compared: if the sodium-based bentonite is absent in the hazardous waste solidification cementing material, the ability to solidify heavy metal ions is reduced, and the ability of sodium-based bentonite to solidify heavy metal ions is better than that of phosphoaluminate cementing material.

[0097] Comparative Example 8 and Example 1 can be compared: if the EDTA compound is absent in the hazardous waste solidification cementing material, the ability to solidify heavy metal ions is reduced.

[0098] Comparative Example 9 and Example 1 can be compared: if the activated carbon is absent in the hazardous waste solidification cementing material, the ability to solidify heavy metal ions is reduced.

[0099] The above describes the preferred embodiments of the present application, but the present application is not limited to the specific details in the above-described embodiments, and various simple modifications can be made to the technical solutions of the present application within the technical concept of the present application, and these simple modifications all belong to the protection scope of the present application.

[0100] In addition, it should be noted that each specific technical feature described in the above-described specific embodiments can be combined in any appropriate manner without contradiction, and in order to avoid unnecessary repetition, the present application will not describe various possible combinations again.

[0101] In addition, various different embodiments of the present application can also be combined in any manner, as long as it does not deviate from the technical concept of the present application, and it should be considered as disclosed content of the present application.

Claims

1. A phosphoaluminate cementitious material for hazardous waste solidification, characterized by, The product comprises: phosphoaluminate cementitious material, bentonite, heavy metal chelating agent, and activated carbon, wherein the weight ratio of the phosphoaluminate cementitious material, bentonite, heavy metal chelating agent, and activated carbon is 60-100:10-40:0-5:1-10; wherein the phosphoaluminate cementitious material is obtained by calcining wet raw materials, and the powdered material in the wet raw materials includes: limestone, bauxite, and apatite; the weight ratio of the heavy metal chelating agent is not zero. In the wet raw material, the weight ratio of limestone, bauxite and apatite is 30-70:30-60:5-20; The weight ratio of powdered material to water in the wet raw material is 100:10-20; The particle size of the powder is no greater than 80 μm.

2. The phosphoaluminate cementitious material for solidification of hazardous waste according to claim 1, characterized by, The wet raw material is pretreated before calcination, including: pressing the wet raw material; The pressing pressure is 20-40 MPa; The calcination shall at least meet the following conditions: heating from 15-35℃ to 1300-1500℃ at a heating rate of 5-10℃ / min, and holding at that temperature for 1-3 hours; The wet raw material undergoes post-treatment after calcination, including: spraying the calcined product with water and turning it over for 1-2 minutes. After spraying is completed, the material is spread out and allowed to air dry naturally using residual heat.

3. The phosphoaluminate cementitious material for solidification of hazardous waste according to claim 1, characterized by, The bentonite is selected from at least one of sodium-based bentonite and microwave-activated bentonite; The microwave-activated bentonite is obtained by microwave activation of natural bentonite, wherein the microwave activation frequency is 1000-5000MHz and the activation time is 5-20min. The heavy metal chelating agent is at least one of ethylenediaminetetraacetic acid compounds or dithiocarbamate compounds; The bentonite has an average particle size of 45-150 μm, and the activated carbon has an average particle size of 10-100 μm.

4. A method for producing the phosphoaluminate cement material for solidification of hazardous waste according to any one of claims 1 to 3, characterized by, The preparation method includes: 1) The limestone, bauxite and apatite are crushed, then ground and sieved to obtain powder. The powder is then mixed with water to obtain wet raw material. The wet raw material is then calcined to obtain phosphoaluminate cementitious material. 2) Mix the phosphoaluminate cementitious material, bentonite, heavy metal chelating agent, and activated carbon to obtain the phosphoaluminate cementitious material for hazardous waste solidification.

5. A hazardous waste utilization mortar, characterized in that, The hazardous waste utilization mortar contains hazardous waste solids in a weight ratio of 1:0.8-1.2 and the phosphoaluminate cementitious material for hazardous waste solidification as described in any one of claims 1-3.

6. The hazardous waste utilization mortar according to claim 5, characterized in that, The hazardous waste utilization mortar must meet at least the following conditions: water-cement ratio of 0.4-0.7, mortar-cement ratio of 1:2-5, and curing time of more than 28 days; The hazardous solid waste is fly ash.

7. The application of a phosphoaluminate cementitious material for solidifying hazardous waste as described in any one of claims 1-3 in the solidification of metal ions.

8. The application according to claim 7, characterized in that, In the application, the phosphoaluminate gelling material for hazardous waste solidification is mixed with water and then a container is made; the heavy metal solution is then placed in the container and left to stand. During the settling process, the container is kept in water for maintenance, and the liquid level inside and outside the container is the same.

9. The application according to claim 8, characterized in that, The water-cement ratio of the phosphoaluminate cementitious material for hazardous waste solidification, after mixing with water, is 0.25-0.35; The maintenance period is more than 28 days.

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