A waste alkali-activated cementitious vanadium extraction tailings filling material and a preparation method thereof

Abstract

The application discloses a waste alkali-activated cemented filling material for vanadium extraction tailings and a preparation method thereof. The raw material of the waste alkali-activated cemented filling material for vanadium extraction tailings comprises solid raw material, alkaline activator and water; wherein, according to mass percentage, the solid raw material comprises vanadium extraction tailings 60%-80%, gypsum 5%-15%, quicklime 5%-15%, and cement 10%-20%; the alkaline activator is obtained by wet oxidation pretreatment of ethylene alkali residue wastewater; the mass of the alkaline activator accounts for 10%-25% of the mass of the solid raw material, and the mass of the water accounts for 15%-30% of the mass of the solid raw material. The ethylene alkali residue wastewater is pretreated by wet oxidation and then used as the alkaline activator to activate the vanadium extraction tailings, so that waste is treated by waste, and the production cost is reduced; the filling material meets the filling strength requirement, the 28-day compressive strength is above 2 MPa, and the leaching liquid test result meets the environmental standard requirement.

Description

Technical Field

[0001] This invention relates to the field of solid waste backfilling technology, and in particular to a waste alkali-activated cemented vanadium extraction tailings backfilling material and its preparation method. Background Technology

[0002] Vanadium extraction tailings refer to the solid waste remaining after vanadium is extracted from vanadium ore through physical and / or chemical processes. Currently, the utilization rate of vanadium extraction tailings is low, and large-scale tailings accumulation occupies land, damages the ecological environment, and restricts the development of the vanadium extraction industry. The current stockpile of vanadium extraction tailings is as high as billions of tons. Therefore, the comprehensive utilization of vanadium extraction tailings has been extensively studied. Using vanadium extraction tailings for backfilling in mining goaf areas can not only reduce waste emissions and protect the mining environment, but also reduce the preparation cost of backfill materials. However, there is limited research on the preparation of backfill materials from vanadium extraction tailings. Although vanadium extraction tailings contain a certain amount of silicon and aluminum, their phase structure is more complex than that of common siliceous and aluminous raw materials such as slag and fly ash. In vanadium extraction tailings, silicon and aluminum mostly exist as stable mineral phases with high crystallinity and high polymerization, making the release of active components difficult.

[0003] Ethylene alkali wastewater (i.e., ethylene alkali residue wastewater) is wastewater generated during the alkali washing process of ethylene plant cracking gas to remove acidic gases (mainly H2S and CO2) from the cracked gas. It is characterized by its complex composition, containing high concentrations of organic matter, sulfides, inorganic salts, and odorous volatile components such as thiols. After wet oxidation treatment, sodium sulfide and organic sulfides in the ethylene alkali residue wastewater are converted into thiosulfate and sulfate ions, but problems such as high COD, high color, and difficulty in resource utilization still exist.

[0004] Therefore, there is an urgent need to provide a backfill material for vanadium extraction tailings activated by alkali and its preparation method, so as to solve the problem of resource utilization of vanadium extraction tailings and ethylene waste alkali solution. Summary of the Invention

[0005] The purpose of this invention is to overcome the above-mentioned technical deficiencies and propose a waste alkali-activated cemented vanadium extraction tailings backfill material and its preparation method, thereby solving the technical problems of limited research on the preparation of backfill materials for vanadium extraction tailings and the difficulty in resource utilization of ethylene waste alkali liquid in the prior art.

[0006] In a first aspect, the present invention provides a backfill material for vanadium extraction tailings activated by alkali, the raw materials of which include: solid raw materials, alkaline activator and water; wherein, by mass percentage, the solid raw materials include: 60%-80% vanadium extraction tailings, 5%-15% gypsum, 5%-15% quicklime, and 10%-20% cement; the alkaline activator is obtained by wet oxidation pretreatment of ethylene alkali slag wastewater; the mass of the alkaline activator accounts for 10%-25% of the mass of the solid raw materials, and the mass of water accounts for 15%-30% of the mass of the solid raw materials.

[0007] Secondly, this invention provides a method for preparing a backfill material for vanadium extraction tailings activated by alkali, comprising the following steps: Solid raw materials, alkaline activator and water are mixed evenly, and then molded and cured to obtain waste alkali activated cemented vanadium extraction tailings backfill material.

[0008] Compared with the prior art, the beneficial effects of the present invention include: This invention utilizes ethylene alkali residue wastewater, pretreated by wet oxidation, as an alkaline activator to stimulate vanadium extraction tailings, achieving waste-to-waste treatment and reducing production costs. Simultaneously, the method improves the comprehensive utilization rate of vanadium extraction tailings and ethylene alkali residue wastewater, reducing the environmental risks caused by vanadium extraction tailings accumulation and ethylene alkali residue wastewater. The backfill material of this invention meets backfill strength requirements, with a 28-day compressive strength exceeding 2 MPa, and the leachate meets environmental standards, making it suitable for backfilling and remediation of mining goaf areas. The preparation method of this invention is simple and easy to implement. Detailed Implementation

[0009] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0010] Vanadium extraction tailings refer to the solid waste remaining after vanadium is extracted from vanadium ore through physical and / or chemical processes. Currently, the utilization rate of vanadium extraction tailings is low, and large quantities of tailings are stockpiled, encroaching on land, damaging the ecological environment, and hindering the development of the vanadium extraction industry. Using vanadium extraction tailings for backfilling mined-out areas can not only reduce waste emissions and protect the mining environment but also lower the cost of backfill material preparation. However, there is limited research on the preparation of backfill materials from vanadium extraction tailings.

[0011] Ethylene alkali wastewater (i.e., ethylene alkali residue wastewater) is wastewater generated during the alkali washing process of ethylene plant cracking gas to remove acidic gases (mainly H2S and CO2) from the cracking gas. It is characterized by its complex composition, containing high concentrations of organic matter, sulfides, inorganic salts, and odorous volatile components such as thiols. After wet oxidation treatment, sodium sulfide and organic sulfides in the ethylene alkali residue wastewater are converted into thiosulfate and sulfate ions, but problems such as high COD, high color, and difficulty in resource utilization still exist.

[0012] This invention utilizes ethylene alkali residue wastewater, after wet oxidation pretreatment (its main components include sodium hydroxide and sodium sulfate, wherein the sodium sulfate generated after pretreatment acts as a curing agent to enhance the strength of the backing material), as an alkaline activator to activate vanadium extraction tailings, thereby achieving waste-to-waste treatment, improving the resource utilization rate of vanadium extraction tailings and ethylene alkali residue wastewater, and obtaining backing materials that meet the strength and leachate requirements.

[0013] In a first aspect, the present invention provides a backfill material for vanadium extraction tailings activated by alkali, the raw materials of which include: solid raw materials, alkaline activator and water; wherein, by mass percentage, the solid raw materials include: 60%-80% vanadium extraction tailings, 5%-15% gypsum, 5%-15% quicklime, and 10%-20% cement; the alkaline activator is obtained by wet oxidation pretreatment of ethylene alkali slag wastewater; the mass of the alkaline activator accounts for 10%-25% of the mass of the solid raw materials, and the mass of water accounts for 15%-30% of the mass of the solid raw materials.

[0014] In this invention, vanadium extraction tailings, under the action of an alkaline activator, dissolve active silica-alumina components to participate in the cementitious reaction, and also act as aggregate to fill the gaps and enhance the strength of the filling material. The hydration product of quicklime, Ca(OH)2, is the key calcium source for generating cementitious products, which is beneficial for activating the potential activity of vanadium extraction tailings. Gypsum reacts with active aluminum and calcium ions in the system to generate ettringite, which can quickly form a network structure and enhance early strength. Cement provides stable early hydration products (CSH gel), further enhancing early strength.

[0015] In this invention, by means of wet oxidation pretreatment, the sulfur in sodium sulfide and / or organic sulfides in ethylene alkali slag wastewater is converted into thiosulfate and / or sulfate, effectively removing the malodor and toxicity of ethylene alkali slag. In particular, highly toxic sulfides and some recalcitrant organic matter are oxidized into harmless or low-toxic substances, thereby reducing the sulfide content in the leachate of the backfill material to meet the Class III requirements of GB / T 14848-2017 Groundwater Quality Standard. At the same time, the generated sodium sulfate acts as a curing agent to improve the strength of the backfill material.

[0016] In this embodiment, the ethylene alkali residue wastewater includes the following components: inorganic sulfides (in the form of S... 2- (Calculated) 30-60g / L, sodium carbonate 40-50g / L, sodium hydroxide 10-30g / L, COD 20-50g / L, pH>13.

[0017] In this embodiment, the wet oxidation pretreatment process includes: using air and / or oxygen as an oxidant to perform wet oxidation pretreatment on ethylene alkali residue wastewater.

[0018] Preferably, the mass ratio of ethylene alkali residue wastewater to oxidant is (100-1000):1, including but not limited to 100:1, 200:1, 400:1, 600:1, 800:1, 1000:1, 1200:1, etc.

[0019] Preferably, a catalyst is added during the wet oxidation pretreatment process.

[0020] More preferably, the catalyst is tannic acid. By using tannic acid as a catalyst, this invention can effectively reduce the reaction temperature and improve the oxidation efficiency, thereby significantly improving the COD removal rate.

[0021] More preferably, the ratio of catalyst to ethylene alkali residue wastewater is 0.1-1g:1L.

[0022] Preferably, during the wet oxidation pretreatment process, the reaction temperature is 190-210℃, the reaction pressure is 1-5MPa, and the reaction time is 2-3h. By controlling the reaction temperature within the above range, this invention enables the oxidation products of ethylene alkali residue wastewater after wet oxidation pretreatment to be mainly sodium sulfate, and ensures complete degradation of organic matter.

[0023] In this embodiment, the ethylene alkali residue wastewater, after wet oxidation pretreatment, includes the following components: inorganic sulfides (in the form of S...). 2- (Calculated) <2mg / L, sodium carbonate 45-60g / L, sodium hydroxide 10-25g / L, COD 2-6g / L, sodium sulfate 100-200g / L, pH>12.

[0024] In this embodiment, the alkaline activator is obtained by pretreating ethylene alkali residue wastewater through wet oxidation and then diluting it with water to a pH ≥ 8 (including but not limited to 8, 8.5, 9, 9.5, 10, 10.5, 11, 11.5, 12, 12.5, 13, etc.). This invention, by diluting the pretreated ethylene alkali residue wastewater with water, can further reduce the content of sulfate, sulfide, and ammonia nitrogen in the leachate without excessively affecting the strength of the backfill material.

[0025] In this embodiment, the vanadium-extraction tailings are the residual waste residue after vanadium-bearing shale has undergone processes such as leaching, extraction, and vanadium precipitation to extract metallic vanadium.

[0026] In this embodiment, the SiO2 content in the vanadium extraction tailings is 50%-70%, and the Al2O3 content is 5%-25%.

[0027] In this embodiment, the composition of the vanadium extraction tailings by mass percentage includes: 50%-70% SiO2, 5%-25% Al2O3, 2%-10% other oxides (including but not limited to MgO, K2O, P2O5, MnO, etc.), and 5%-15% loss on ignition.

[0028] In this embodiment, the vanadium extraction tailings contain more than 60% with a particle size of -0.074 mm and more than 50% with a particle size of -0.038 mm. By controlling the particle size of the vanadium extraction tailings within the above-mentioned range, this invention ensures that its surface can fully contact the alkaline activator to rapidly release active silicon-aluminum components to participate in the gelation reaction.

[0029] Secondly, this invention provides a method for preparing a backfill material for vanadium extraction tailings activated by alkali, comprising the following steps: Solid raw materials, alkaline activator and water are mixed evenly, and then molded and cured to obtain waste alkali activated cemented vanadium extraction tailings backfill material.

[0030] In this embodiment, the process of uniformly mixing the solid raw material, alkaline activator, and water includes: Vanadium extraction tailings, quicklime, gypsum, and cement are mixed evenly to obtain solid raw materials; Mix the alkaline activator and water thoroughly to obtain a mixture; The solid raw materials and the mixture are mixed evenly to obtain a mixed slurry.

[0031] Preferably, the solid raw materials and the mixture are mixed evenly by stirring for 10-20 minutes.

[0032] This invention does not limit the molding method, and those skilled in the art can choose according to the actual situation. For example, casting molding or compression molding can be used.

[0033] Preferably, the molding process includes: pouring the mixed slurry into a mold, pre-curing, and then demolding.

[0034] The pre-curing conditions are as follows: curing temperature 20-25℃, curing humidity 90%-95%, and curing time 24-36 hours.

[0035] In this embodiment, the curing conditions are: curing temperature of 20-25℃, curing humidity of 90%-95%, and curing time of 14-28 days.

[0036] Unless otherwise specified, all reagents used in the following embodiments and comparative examples of the present invention are commercially available chemical reagents or industrial products.

[0037] In the following embodiments and comparative examples of the present invention, the cement is ordinary Portland cement of type PO42.5; by mass percentage, the composition of the vanadium extraction tailings includes: SiO2 65.42%, Al2O3 19.89%, other oxides (MgO, K2O, P2O5, MnO, etc.) 2.22%, and loss on ignition 12.47%; in the vanadium extraction tailings, fineness of -0.074mm accounts for 62.13% and -0.038mm accounts for 53.47%.

[0038] In the following embodiments and comparative examples of the present invention, the ethylene alkali residue wastewater (comprising the following components: inorganic sulfides (as S)) 2-The pretreatment process of ethylene alkali residue wastewater (containing 39.12 g / L of sodium carbonate, 42.75 g / L of sodium hydroxide, 26.45 g / L of sodium hydroxide, 39.47 g / L of COD, and pH 13.46) via wet oxidation is as follows: First, the ethylene alkali residue wastewater is pressurized to 4.5 MPa using a high-pressure pump, while tannic acid is added as a catalyst at a ratio of 0.6 g to 1 L. The high-pressure ethylene alkali residue wastewater is mixed with compressed air at a gas-liquid mass ratio of 410:1 and then enters a heat exchanger to exchange heat with the high-temperature mixed fluid after the reaction. The reactants are preheated to 180°C. The preheated reactants then enter the wet oxidation reactor, where they are heated to 205°C by an electric heater and reacted for 2 hours. Subsequently, they are cooled by heat exchange with a new batch of feed mixed fluid. Finally, gas-liquid separation is performed, and the resulting liquid is the pretreated ethylene alkali residue wastewater (containing the following components: inorganic sulfides (as part of S...). 2- (Total concentrations: 0.87 mg / L, sodium carbonate: 46.76 g / L, sodium hydroxide: 24.83 g / L, COD: 3.19 g / L, sodium sulfate: 142.46 g / L, pH: 12.97).

[0039] Example 1 This embodiment provides a backfill material for vanadium extraction tailings activated by alkali, the raw materials of which include: solid raw materials, alkaline activator and water; wherein, by mass percentage, the components of the solid raw materials are: 70% vanadium extraction tailings, 10% gypsum, 10% quicklime, and 10% cement; the alkaline activator is obtained by diluting the pretreated ethylene alkali residue wastewater with water to pH=10.13; the mass of the alkaline activator is 15% of the mass of the solid raw materials, and the mass of water is 25% of the mass of the solid raw materials.

[0040] Its preparation steps include: (1) Add quicklime, gypsum and cement to the vanadium extraction tailings, mix and stir evenly to obtain solid raw materials; (2) Measure the alkaline activator and water according to the required ratio, mix and stir evenly to obtain a mixture; (3) Mix the solid raw materials with the mixture for 15 minutes, pour it into a 70.7 mm × 70.7 mm × 70.7 mm mold, compact it, and place it in an environment with a temperature of 20℃ and a humidity of 95% for 24 hours for pre-curing. (4) Remove the mold and continue curing for 28 days to obtain waste alkali activated cemented vanadium extraction tailings backfill material.

[0041] Testing showed that the compressive strength of the vanadium-extraction tailings backfill material prepared in this embodiment, after 28 days of curing, was 3.26 MPa. The leachate for the vanadium-extraction tailings backfill material was prepared according to the "Horizontal Oscillation Method for Leaching Toxicity of Solid Waste" (HJ 557). The pH of the leachate was 7.96, and the sulfate content (as shown in SO42-) was [not specified]. 2-(Calculated as): 89 mg / L, sulfides (as S) 2- The concentrations of nitrogen (calculated as N) were 0.0023 mg / L and 0.0104 mg / L, respectively. The leachate test results met the Class III requirements of GB / T 14848-2017 Groundwater Quality Standard.

[0042] Example 2 Unlike Example 1, the alkaline activator was obtained by diluting the pretreated ethylene alkali residue wastewater with water to pH=8.06.

[0043] The compressive strength of the vanadium-extraction tailings backfill material prepared in this embodiment after 28 days of curing was tested to be 2.31 MPa. The leachate for the vanadium-extraction tailings backfill material was prepared according to the "Horizontal Oscillation Method for Leaching Toxicity of Solid Waste" (HJ 557). The pH of the leachate was 7.26, and the sulfate content (as shown in SO42-) was [not specified]. 2- (Calculated as): 78 mg / L, sulfides (as S) 2- The concentrations of nitrogen (calculated as N) were 0.0019 mg / L and 0.0089 mg / L, respectively. The leachate test results met the Class III requirements of GB / T 14848-2017 Groundwater Quality Standard.

[0044] Example 3 Unlike Example 1, the alkaline activator was obtained by diluting the pretreated ethylene alkali residue wastewater with water to pH=12.04.

[0045] Testing showed that the compressive strength of the vanadium-extraction tailings backfill material prepared in this embodiment, after 28 days of curing, was 3.31 MPa. The leachate for the vanadium-extraction tailings backfill material was prepared according to the "Horizontal Oscillation Method for Leaching Toxicity of Solid Waste" (HJ 557). The pH of the leachate was 8.31, and the sulfate content (as shown in SO42-) was [not specified]. 2- (Calculated as): 148 mg / L, sulfides (as S) 2- The concentrations of nitrogen (calculated as N) were 0.0038 mg / L and 0.0142 mg / L, respectively. The leachate test results met the Class III requirements of GB / T 14848-2017 Groundwater Quality Standard.

[0046] Example 4 Unlike Example 1, the alkaline activator is the pretreated ethylene alkali residue wastewater described above.

[0047] Testing showed that the compressive strength of the vanadium-extraction tailings backfill material prepared in this embodiment, after 28 days of curing, was 3.41 MPa. The leachate for the vanadium-extraction tailings backfill material was prepared according to the "Horizontal Oscillation Method for Leaching Toxicity of Solid Waste" (HJ 557). The pH of the leachate was 8.46, and the sulfate content (as shown in SO42-) was [not specified]. 2- (Calculated as): 192 mg / L, sulfides (as S) 2-The concentrations of nitrogen (calculated as N) were 0.0062 mg / L and 0.0174 mg / L, respectively. The leachate test results met the Class III requirements of GB / T 14848-2017 Groundwater Quality Standard.

[0048] Example 5 Unlike Example 1, the raw materials for the vanadium extraction tailings backfill material activated by alkali include: solid raw materials, alkaline activator, and water; wherein, by mass percentage, the solid raw materials consist of: 60% vanadium extraction tailings, 15% gypsum, 5% quicklime, and 20% cement; the alkaline activator is obtained by diluting the pretreated ethylene alkali residue wastewater with water to pH=10.13; the mass of the alkaline activator is 10% of the mass of the solid raw materials, and the mass of water is 30% of the mass of the solid raw materials.

[0049] The preparation steps are the same as in Example 1.

[0050] Testing showed that the compressive strength of the vanadium-extraction tailings backfill material prepared in this embodiment, after 28 days of curing, was 3.23 MPa. The leachate for the vanadium-extraction tailings backfill material was prepared according to the "Horizontal Oscillation Method for Leaching Toxicity of Solid Waste" (HJ 557). The pH of the leachate was 8.04, and the sulfate content (as SO42-) was [not specified]. 2- (Calculated as): 92 mg / L, sulfides (as S) 2- The concentrations of nitrogen (calculated as N) were 0.0027 mg / L and 0.0097 mg / L, respectively. The leachate test results met the Class III requirements of GB / T 14848-2017 Groundwater Quality Standard.

[0051] Example 6 Unlike Example 1, the raw materials for the vanadium extraction tailings backfill material activated by alkali include: solid raw materials, alkaline activator, and water; wherein, by mass percentage, the solid raw materials consist of: 80% vanadium extraction tailings, 5% gypsum, 5% quicklime, and 10% cement; the alkaline activator is obtained by diluting the pretreated ethylene alkali residue wastewater with water to pH=10.13; the mass of the alkaline activator is 25% of the mass of the solid raw materials, and the mass of water is 15% of the mass of the solid raw materials.

[0052] The preparation steps are the same as in Example 1.

[0053] Testing showed that the compressive strength of the vanadium-extraction tailings backfill material prepared in this embodiment, after 28 days of curing, was 2.06 MPa. The leachate for the vanadium-extraction tailings backfill material was prepared according to the "Horizontal Oscillation Method for Leaching Toxicity of Solid Waste" (HJ 557). The pH of the leachate was 7.82, and the sulfate content (as shown in SO42-) was [not specified]. 2- (Calculated as): 84 mg / L, sulfides (as S) 2-The concentrations of nitrogen (calculated as N) were 0.0022 mg / L and 0.0093 mg / L, respectively. The leachate test results met the Class III requirements of GB / T 14848-2017 Groundwater Quality Standard.

[0054] Comparative Example 1 Unlike Example 1, the alkaline activator was obtained by directly diluting the above-mentioned ethylene alkaline wastewater (pH 13.46) with water to pH 10.08 without wet oxidation pretreatment.

[0055] Testing showed that the compressive strength of the vanadium-extraction tailings backfill material prepared in this comparative example was 1.94 MPa after 28 days of curing. The leachate for the vanadium-extraction tailings backfill material was prepared according to the "Horizontal Oscillation Method for Leaching Toxicity of Solid Waste" (HJ 557). The pH of the leachate was 8.0, and the sulfate content (as shown in SO42-) was [not specified]. 2- (Calculated as): 75 mg / L, sulfides (as S) 2- The concentrations of nitrogen (calculated as N) were 0.129 mg / L and 0.0227 mg / L, respectively. The leachate test results did not meet the Class III requirements of the "GB / T 14848-2017 Groundwater Quality Standard".

[0056] Comparative Example 2 Unlike Example 1, the alkaline activator was a mixed solution of sodium hydroxide and sodium sulfate, with a sodium sulfate content of 0.15 g / L and a pH of 10.11.

[0057] Testing showed that the compressive strength of the vanadium-extraction tailings backfill material prepared in this comparative example after 28 days of curing was 3.34 MPa. The leachate for the vanadium-extraction tailings backfill material was prepared according to the "Horizontal Oscillation Method for Leaching Toxicity of Solid Waste" (HJ 557). The pH of the leachate was 7.8, and the sulfate content (as shown in SO42-) was [not specified]. 2- (Calculated as): 72 mg / L, sulfides (as S) 2- The concentrations of nitrogen (calculated as N) were 0.0012 mg / L and 0.0028 mg / L, respectively. The leachate test results met the Class III requirements of GB / T 14848-2017 Groundwater Quality Standard.

[0058] Comparative Example 3 Unlike Example 1, the composition of the solid raw materials by mass percentage is: 49% vanadium extraction tailings, 17% gypsum, 17% quicklime, and 17% cement.

[0059] Testing showed that the compressive strength of the vanadium-extraction tailings backfill material prepared in this comparative example after 28 days of curing was 4.36 MPa. The leachate for the vanadium-extraction tailings backfill material was prepared according to the "Horizontal Oscillation Method for Leaching Toxicity of Solid Waste" (HJ 557). The pH of the leachate was 7.64, and the sulfate content (as shown in SO42-) was [not specified]. 2-(Calculated as): 83 mg / L, sulfides (as S) 2- The concentrations of nitrogen (calculated as N) were 0.0016 mg / L and 0.0096 mg / L, respectively. The leachate test results met the Class III requirements of GB / T 14848-2017 Groundwater Quality Standard.

[0060] Comparative Example 4 Unlike Example 1, the composition of the solid raw materials by mass percentage is: 85% vanadium extraction tailings, 5% gypsum, 5% quicklime, and 5% cement.

[0061] Testing showed that the compressive strength of the vanadium-extraction tailings backfill material prepared in this comparative example after 28 days of curing was 1.68 MPa. The leachate for the vanadium-extraction tailings backfill material was prepared according to the "Horizontal Oscillation Method for Leaching Toxicity of Solid Waste" (HJ 557). The pH of the leachate was 7.45, and the sulfate content (as shown in SO42-) was [not specified]. 2- (Calculated as): 77 mg / L, sulfides (as S) 2- The concentrations of nitrogen (calculated as N) were 0.0021 mg / L and 0.0103 mg / L, respectively. The leachate test results met the Class III requirements of GB / T 14848-2017 Groundwater Quality Standard.

[0062] Comparative Example 5 Unlike Example 1, the composition of the solid raw materials by mass percentage is: 78% vanadium extraction tailings, 11% quicklime, and 11% cement.

[0063] Testing showed that the compressive strength of the vanadium-extraction tailings backfill material prepared in this comparative example after 28 days of curing was 1.86 MPa. The leachate for the vanadium-extraction tailings backfill material was prepared according to the "Horizontal Oscillation Method for Leaching Toxicity of Solid Waste" (HJ 557). The pH of the leachate was 7.42, and the sulfate content (as shown in SO42-) was [not specified]. 2- (Calculated as): 86 mg / L, sulfides (as S) 2- The concentrations of nitrogen (calculated as N) were 0.0027 mg / L and 0.0094 mg / L, respectively. The leachate test results met the Class III requirements of GB / T 14848-2017 Groundwater Quality Standard.

[0064] Comparative Example 6 Unlike Example 1, the composition of the solid raw materials by mass percentage is: 78% vanadium extraction tailings, 11% gypsum, and 11% cement.

[0065] Testing showed that the compressive strength of the vanadium-extraction tailings backfill material prepared in this comparative example after 28 days of curing was 1.73 MPa. The leachate for the vanadium-extraction tailings backfill material was prepared according to the "Horizontal Oscillation Method for Leaching Toxicity of Solid Waste" (HJ 557). The pH of the leachate was 7.82, and the sulfate content (as shown in SO42-) was [not specified]. 2-(Calculated as): 93 mg / L, sulfides (as S) 2- The concentrations of nitrogen (calculated as N) were 0.0024 mg / L and 0.0087 mg / L, respectively. The leachate test results met the Class III requirements of GB / T 14848-2017 Groundwater Quality Standard.

[0066] Comparative Example 7 Unlike Example 1, the composition of the solid raw materials by mass percentage is: 78% vanadium extraction tailings, 11% gypsum, and 11% quicklime.

[0067] Testing showed that the compressive strength of the vanadium-extraction tailings backfill material prepared in this comparative example after 28 days of curing was 1.24 MPa. The leachate for the vanadium-extraction tailings backfill material was prepared according to the "Horizontal Oscillation Method for Leaching Toxicity of Solid Waste" (HJ 557). The pH of the leachate was 7.68, and the sulfate content (as shown in SO42-) was [not specified]. 2- (Calculated as): 91 mg / L, sulfides (as S) 2- The concentrations of nitrogen (calculated as N) were 0.0030 mg / L and 0.0089 mg / L, respectively. The leachate test results met the Class III requirements of GB / T 14848-2017 Groundwater Quality Standard.

[0068] The results above show that the waste alkali activated cemented vanadium extraction tailings backfill material prepared in the embodiments of the present invention has a 28-day compressive strength > 2MPa, and the leachate of the backfill material meets the requirements of GB / T 14848-2017 Groundwater Quality Standard.

[0069] The comparison of Examples 1-3 shows that, within a suitable pH range, the compressive strength of the filling material increases with increasing pH. Although the content of sulfate, sulfide, and ammonia nitrogen in the leachate performance test also increases, it still meets the Class III requirements of GB / T 14848-2017 Groundwater Quality Standard.

[0070] Compared with Example 1, in Comparative Example 1, the strength of the vanadium tailings backfill material decreased and the sulfide content exceeded the standard after the ethylene alkali residue wastewater without wet oxidation pretreatment was diluted and used as an alkaline activator. The leaching solution test did not meet the Class III requirements of GB / T14848-2017 Groundwater Quality Standard. This indicates that wet oxidation pretreatment of ethylene alkali residue wastewater can not only reduce the sulfide content in the leaching solution, but also improve the strength of the backfill material.

[0071] Compared with Example 1, in Comparative Example 2, a mixed solution of sodium hydroxide and sodium sulfate with a pH of 10.11 was used as an alkaline activator. The strength of the filling material was not much different from that in Example 1. This shows that using the pretreated ethylene alkali residue wastewater formed by wet oxidation pretreatment diluted with water to the target pH as an alkaline activator can achieve the same effect as using sodium hydroxide and sodium sulfate as raw materials. This is not only conducive to the resource utilization of ethylene alkali residue wastewater, but also conducive to reducing production costs.

[0072] Compared with Example 1, the proportion of vanadium extraction tailings in Comparative Example 3 was too low. Although the strength of the backing material was improved and the performance of the leachate met the requirements, the production cost was increased. In Comparative Example 4, the proportion of vanadium extraction tailings was too high, and the strength of the backing material decreased significantly. This shows that the proportion of vanadium extraction tailings is within an appropriate range, which can balance performance and cost.

[0073] Compared with Example 1, in Comparative Examples 5-7, where gypsum, quicklime, and cement were not added, the strength of the resulting backfill materials was significantly reduced. This indicates that by using vanadium extraction tailings, gypsum, quicklime, and cement as solid raw materials, their synergistic effect can be achieved, resulting in backfill materials with high strength and leachate that meet the Class III requirements of GB / T 14848-2017 Groundwater Quality Standard.

[0074] The specific embodiments of the present invention described above do not constitute a limitation on the scope of protection of the present invention. Any other corresponding changes and modifications made in accordance with the technical concept of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A backfill material for vanadium extraction tailings activated by alkali cementation, characterized in that, The raw materials include: solid raw materials, alkaline activator, and water; among which, By mass percentage, the solid raw materials include: 60%-80% vanadium extraction tailings, 5%-15% gypsum, 5%-15% quicklime, and 10%-20% cement; The alkaline activator is obtained by wet oxidation pretreatment of ethylene alkali residue wastewater. The alkaline activator accounts for 10%-25% of the mass of the solid raw material; The water accounts for 15%-30% of the mass of the solid raw material.

2. The waste alkali-activated cemented vanadium extraction tailings backfill material according to claim 1, characterized in that, The ethylene alkali residue wastewater contains the following components: inorganic sulfides 30-60 g / L, sodium carbonate 40-50 g / L, sodium hydroxide 10-30 g / L, COD 20-50 g / L, and pH > 13.

3. The waste alkali-activated cemented vanadium extraction tailings backfill material according to claim 1, characterized in that, The wet oxidation pretreatment process includes: using air and / or oxygen as an oxidant to perform wet oxidation pretreatment on the ethylene alkali residue wastewater; wherein... The mass ratio of the ethylene alkali residue wastewater to the oxidant is (100-1000):1; and / or, In the wet oxidation pretreatment process, a catalyst, specifically tannic acid, is also added. The ratio of the catalyst to the ethylene alkali residue wastewater is 0.1-1 g: 1 L; and / or, During the wet oxidation pretreatment process, the reaction temperature is 190-210℃, the reaction pressure is 1-5MPa, and the reaction time is 2-3h.

4. The waste alkali-activated cemented vanadium extraction tailings backfill material according to claim 1, characterized in that, The ethylene alkali residue wastewater, after wet oxidation pretreatment, comprises the following components: inorganic sulfides <2mg / L, sodium carbonate 45-60g / L, sodium hydroxide 10-25g / L, COD 2-6g / L, sodium sulfate 100-200g / L, and pH >12.

5. The waste alkali-activated cemented vanadium extraction tailings backfill material according to claim 1, characterized in that, The alkaline activator is obtained by pretreating the ethylene alkali residue wastewater with wet oxidation and then diluting it with water to a pH ≥ 8.

6. The waste alkali-activated cemented vanadium extraction tailings backfill material according to claim 1, characterized in that, The vanadium extraction tailings contain 50%-70% SiO2 and 5%-25% Al2O3.

7. The waste alkali-activated cemented vanadium extraction tailings backfill material according to claim 1, characterized in that, In the vanadium extraction tailings, a fineness of -0.074 mm accounts for more than 60%, and a fineness of -0.038 mm accounts for more than 50%.

8. A method for preparing a waste alkali-activated cemented vanadium extraction tailings backfill material as described in any one of claims 1-7, characterized in that, Includes the following steps: Solid raw materials, alkaline activator and water are mixed evenly, and then molded and cured to obtain waste alkali activated cemented vanadium extraction tailings backfill material.

9. The preparation method of the waste alkali-activated cemented vanadium extraction tailings backfill material according to claim 8, characterized in that, The molding process includes: pouring the mixed slurry into a mold, pre-curing, and then demolding; wherein... The pre-curing conditions are: curing temperature of 20-25℃, curing humidity of 90%-95%, and curing time of 24-36 hours.

10. The preparation method of the waste alkali-activated cemented vanadium extraction tailings backfill material according to claim 8, characterized in that, The curing conditions are: curing temperature of 20-25℃, curing humidity of 90%-95%, and curing time of 14-28 days.