Red mud-lead-zinc tailings geopolymer solidified material and solidified body

Abstract

The application discloses a red mud-lead-zinc tailings geopolymer consolidation material and a solidified body. The raw materials of the consolidation material include, in terms of weight parts, 70-80 parts of red mud-lead-zinc tailings mixture, 10-20 parts of admixture and 5-10 parts of additive. The application utilizes the strong alkalinity of the red mud to stimulate the potential hydration activity of the lead-zinc tailings, reduces the effusion of the alkaline substances in the red mud and reduces the frosting phenomenon, and utilizes the hydration products to solidify and stabilize the lead-zinc ions in the lead-zinc tailings. Meanwhile, by adding the admixture and the additive, the hydration reaction is further promoted, the amorphous N-A-S-H gel is generated, the lead-zinc heavy metals have better solidification effect, and finally the lead-zinc ions in the leaching liquid of the solidified body formed after solidification can meet the surface water II standard. Meanwhile, the solidified body has good mechanical strength and can meet the application requirements in the road engineering, tailing filling and building material fields.

Description

Technical Field

[0001] This invention relates to the field of red mud resource utilization technology, and in particular to a red mud-lead-zinc tailings base polymer consolidation material and solidified body. Background Technology

[0002] Red mud is a major solid waste generated by the alumina industry. It is highly alkaline, posing significant environmental pollution and low resource utilization rates. Currently, red mud is primarily stockpiled globally. With the rapid development of the global alumina industry, red mud has become a major factor affecting the healthy development of the aluminum industry. Tailings are the unusable waste residue remaining after ore beneficiation processes such as crushing, grinding, and separation, discharged in slurry form. Large amounts of tailings accumulate in tailings ponds year-round, occupying valuable land resources. Without treatment, heavy metals such as lead and zinc in tailings seep into surrounding soil and water bodies, causing serious environmental pollution.

[0003] Solidification and stabilization of heavy metal-contaminated tailings is a common technology for tailings treatment. Solidification and stabilization can reduce the leaching and migration of heavy metals in tailings, thus reducing heavy metal pollution of surrounding soil and water bodies. Furthermore, the solidified tailings form a solid body with good mechanical strength, suitable for use in roadbed and building materials. Chinese Patent CN 113387669 B discloses a red mud-phosphogypsum-based heavy metal solidifier, its preparation method, and its application. This patent describes a process where undisturbed phosphogypsum and red mud are dried, mixed evenly, and then water-quenched alkaline ferrochemical slag and additives are added and ground to obtain the red mud-phosphogypsum-based heavy metal solidifier. This patent applies the above-mentioned red mud-phosphogypsum-based heavy metal solidifier to solidify lead-zinc tailings, reducing environmental pollution caused by red mud and phosphogypsum stockpiles and replacing cement, thus lowering the cost of tailings solidification and stabilization. However, the resulting solid body has low strength, and the lead-zinc leaching concentration remains high.

[0004] Therefore, there is an urgent need to provide a new treatment technology based on red mud and lead-zinc tailings to improve the solidification effect of lead-zinc tailings. Summary of the Invention

[0005] The purpose of this invention is to overcome the above-mentioned technical deficiencies and propose a red mud-lead-zinc tailings base polymer consolidation material and solidified body, which solves the technical problems of low strength and high lead-zinc leaching concentration of the solidified body formed after lead-zinc tailings solidification in the prior art.

[0006] In a first aspect, the present invention provides a red mud-lead-zinc tailings base polymer consolidation material, which, by weight, comprises: 70-80 parts of red mud-lead-zinc tailings mixture, 10-20 parts of admixture, and 5-10 parts of additive; wherein the admixture is at least one of water-quenched alkaline iron slag powder, silica fume, and metakaolin; and the additive is at least one of sodium hydroxide, calcium formate, water glass, potassium hydroxide, aluminum sulfate, and sodium fluorosilicate.

[0007] In a second aspect, the present invention provides a solidified red mud-lead-zinc tailings base polymer, which is obtained by mixing the red mud-lead-zinc tailings base polymer solidification material provided in the first aspect of the present invention with water and then curing it.

[0008] Compared with the prior art, the beneficial effects of the present invention include: This invention utilizes the strong alkalinity of red mud to stimulate the potential hydration activity of lead-zinc tailings, reducing the outflow of alkaline substances from the red mud and minimizing efflorescence. It also utilizes the hydration products to solidify and stabilize lead and zinc ions in the tailings. Simultaneously, by adding admixtures and additives, the hydration reaction is further promoted to generate amorphous NASH gel, thus achieving better solidification of heavy metals like lead and zinc. Ultimately, the leachate from the solidified body meets the Class II surface water standard for lead and zinc ions. Furthermore, the solidified body possesses good mechanical strength, meeting the application requirements in road engineering, tailings backfilling, and building materials. 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] In a first aspect, the present invention provides a red mud-lead-zinc tailings base polymer consolidation material, the raw materials of which, by weight, include: 70-80 parts of red mud-lead-zinc tailings mixture, 10-20 parts of admixture, and 5-10 parts of additive.

[0011] This invention utilizes the strong alkalinity of red mud to stimulate the potential hydration activity of minerals such as SiO2 and Al2O3 in lead-zinc tailings, causing them to undergo hydration reactions with each other, reducing the outflow of alkaline substances from the red mud and reducing the blooming phenomenon; and utilizes the hydration products to solidify and stabilize lead and zinc ions in the lead-zinc tailings. This invention, based on the hydration reaction of red mud and lead-zinc tailings, adds admixtures and additives to further promote the hydration reaction, generating an amorphous NASH gel (N: Na₂O, S: SiO₂, A: Al₂O₃, H: H₂O). Its chemical composition is similar to natural zeolite materials, consisting of cyclic molecular chains. Heavy metal lead and zinc ions are segmented and surrounded within the closed cavities formed by these cyclic molecules, thus achieving better solidification of lead and zinc. Simultaneously, the alkali metal ions in the geopolymer have excellent ion exchange properties, allowing them to exchange with lead and zinc ions, thus stabilizing the process. Ultimately, the leachate from the solidified body meets the Class II surface water standard for lead and zinc ions. Furthermore, the solidified body possesses good mechanical strength, meeting the application requirements in road engineering, tailings backfilling, and building materials. However, the dosage of admixtures or additives should not be too high or too low. If the amount of admixtures or additives is too high, it will increase the cost; if the amount of admixtures or additives is too low, it will result in lower strength of the solidified body and increased leaching rate of heavy metals.

[0012] In this embodiment, the content of Al2O3 in the red mud is ≥35%, and the total content of SiO2 and Al2O3 in the lead-zinc tailings is ≥50%.

[0013] In this embodiment, the mass ratio of red mud to lead-zinc tailings in the red mud-lead-zinc tailings mixture is 1:(0.25-0.5). If the ratio is too high or too low, it will lead to a poorer solidification and stabilization effect on lead and zinc ions in the lead-zinc tailings and a decrease in the strength of the solidified body.

[0014] In this embodiment, the admixture is at least one of water-quenched alkaline iron slag powder, silica fume, and metakaolin. The aforementioned admixture is a potentially active material that can couple and stimulate the hydration activity of red mud-lead-zinc tailings, accelerating the hydration hardening reaction, thereby improving the strength of the solidified body and the stabilizing effect on lead and zinc ions in the lead-zinc tailings.

[0015] In some preferred embodiments of the present invention, the admixture is composed of the following components by weight percentage: 40%-50% water-quenched alkaline iron slag powder, 25%-35% silica fume, and 20%-25% metakaolin. By selecting the above-mentioned types and proportions of admixtures, the present invention can leverage the synergistic effect of the three components, further improving the solidification and stabilization effect of lead and zinc ions in lead-zinc tailings and the strength of the solidified body.

[0016] In this embodiment, the additive is at least one of sodium hydroxide, calcium formate, water glass, potassium hydroxide, aluminum sulfate, and sodium fluorosilicate.

[0017] In some preferred embodiments of the present invention, the admixture is composed of the following components by weight percentage: sodium hydroxide 40%-55%, calcium formate 3%-6%, water glass 5%-15%, potassium hydroxide 5%-15%, aluminum sulfate 15%-25%, and sodium fluorosilicate 5%-15%. By selecting the above-mentioned types and proportions of admixtures, the present invention can leverage the synergistic effect of each component, further improving the solidification and stabilization effect of lead and zinc ions in lead-zinc tailings and the strength of the solidified body.

[0018] In some preferred embodiments of the present invention, the additive is dried and ground into powder, and the residue on a 200-mesh sieve is ≤10%.

[0019] In this embodiment, the uniformity of the above-mentioned red mud-lead-zinc tailings base polymer consolidation material is ≥90%, and the particle size is ≤10μm.

[0020] In some specific embodiments of the present invention, the uniformity of the red mud-lead-zinc tailings base polymer consolidation material is ≥90% and the particle size is ≤10μm by grinding the mixture of red mud-lead-zinc tailings, admixtures and additives.

[0021] In a second aspect, the present invention provides a solidified red mud-lead-zinc tailings base polymer, which is obtained by mixing the red mud-lead-zinc tailings base polymer solidification material provided in the first aspect of the present invention with water and then curing it.

[0022] In this invention, the red mud-lead-zinc tailings base polymer solidification material, formed by mixing and curing with water, is an amorphous aluminosilicate polymer with a three-dimensional network structure. It is formed by cross-linking [SiO4] tetrahedra and [AlO4] tetrahedra through shared oxygen atoms. The alkali metal cations (such as Na) are present in the solidified material. + K + The sodium salts (such as [AlO4] tetrahedra) are distributed in a three-dimensional network, balancing the negative charge of the [AlO4] tetrahedra. This can stabilize the sodium salts in the red mud, thereby reducing the blooming phenomenon caused by the high alkali content of the red mud. The hydration products can be used to solidify and stabilize the lead and zinc ions in the lead and zinc tailings. At the same time, the solidified body has excellent mechanical strength.

[0023] In this embodiment, the mass ratio of the red mud-lead-zinc tailings base polymer consolidation material to water is 1:(0.3-0.4).

[0024] In this embodiment, the curing temperature is 20℃±3℃, and the curing humidity is greater than 95%. This invention does not limit the curing time; those skilled in the art can select it according to actual conditions. For example, it can be 3 days, 7 days, 28 days, etc.

[0025] Example 1 (1) The original red mud (Al2O3 content of about 45%) and lead-zinc tailings (SiO2 content of about 40% and Al2O3 content of about 10%) were dried at 150℃. The mass ratio of red mud to lead-zinc tailings was 1:0.25. The mixture was mechanically stirred in a mixing chamber to obtain a red mud-lead-zinc tailings mixture.

[0026] (2) 70 parts of red mud-lead-zinc tailings mixture and 10 parts of additives, wherein the additives are solid powder composed of sodium hydroxide, calcium formate, water glass, potassium hydroxide, aluminum sulfate and sodium fluorosilicate in a mass ratio of 5:0.3:0.5:1:2:0.5, which are added to the mixing and grinding system according to the corresponding weight ratio. The grinding time is 20 minutes to obtain red mud-lead-zinc tailings powder.

[0027] (3) 10 parts of red mud-lead-zinc tailings powder and admixture (by weight percentage, 40% water-quenched alkaline iron slag powder, 35% silica fume, and 25% metakaolin) are fed into a vertical grinding mill and ground evenly to prepare a red mud-lead-zinc tailings base polymer consolidation material with uniformity ≥95% and particle size ≤10μm.

[0028] Example 2 (1) The original red mud (Al2O3 content of about 45%) and lead-zinc tailings (SiO2 content of about 40% and Al2O3 content of about 10%) were dried at 150℃. The mass ratio of red mud to lead-zinc tailings was 1:0.5. The mixture was mechanically stirred in a mixing chamber to obtain a red mud-lead-zinc tailings mixture.

[0029] (2) 80 parts of red mud-lead-zinc tailings mixture and 5 parts of additives, wherein the additives are solid powder composed of sodium hydroxide, calcium formate, water glass, potassium hydroxide, aluminum sulfate and sodium fluorosilicate in a mass ratio of 4:0.5:1:0.5:1.5:1, which are added to the mixing and grinding system according to the corresponding weight ratio. The grinding time is 20 minutes to obtain red mud-lead-zinc tailings powder.

[0030] (3) Red mud-lead-zinc tailings powder and 20 parts of admixture (by weight percentage, 50% water-quenched alkaline iron slag powder, 25% silica fume, and 25% metakaolin) are ground uniformly in a vertical grinding mill to prepare a red mud-lead-zinc tailings base polymer consolidation material with uniformity ≥95% and particle size ≤10μm.

[0031] Example 3 (1) The original red mud (Al2O3 content of about 45%) and lead-zinc tailings (SiO2 content of about 40% and Al2O3 content of about 10%) were dried at 150℃. The mass ratio of red mud to lead-zinc tailings was 1:0.4. The mixture was mechanically stirred in a mixing chamber to obtain a red mud-lead-zinc tailings mixture.

[0032] (2) 70 parts of red mud-lead-zinc tailings mixture and 8 parts of additives, wherein the additives are solid powder composed of sodium hydroxide, calcium formate, water glass, potassium hydroxide, aluminum sulfate and sodium fluorosilicate in a mass ratio of 5:0.3:0.5:1:2:0.5, which are added to the mixing and grinding system according to the corresponding weight ratio, and the grinding time is 20 minutes to obtain red mud-lead-zinc tailings powder.

[0033] (3) Red mud-lead-zinc tailings powder and 15 parts of admixture (by weight percentage, 50% water-quenched alkaline iron slag powder, 30% silica fume, and 20% metakaolin) are ground uniformly in a vertical grinding mill to prepare a red mud-lead-zinc tailings base polymer consolidation material with uniformity ≥95% and particle size ≤10μm.

[0034] Comparative Example 1 The raw red mud was dried at 150℃ and then ground to obtain red mud powder with a particle size ≤10μm.

[0035] Comparative Example 2 The raw lead-zinc tailings were dried at 150℃ and then ground to obtain lead-zinc tailings powder with a particle size ≤10μm.

[0036] Comparative Example 3 Compared with Example 1, the only difference is that the mass ratio of red mud to lead-zinc tailings is 1:0.2.

[0037] Comparative Example 4 Compared with Example 1, the only difference is that the mass ratio of red mud to lead-zinc tailings is 1:0.6.

[0038] Comparative Example 5 Compared with Example 1, the only difference is that the admixture does not contain metakaolin, and the total amount of admixture and the ratio of the other two components are the same as in Example 1.

[0039] Comparative Example 6 Compared with Example 1, the only difference is that the admixture does not contain silica fume, and the total amount of admixture and the ratio of the other two components are the same as in Example 1.

[0040] Comparative Example 7 Compared with Example 1, the only difference is that the lead-zinc tailings are added only after grinding in step (3) (i.e., the lead-zinc tailings are not mixed and ground with red mud, additives, and admixtures), and the particle size of the lead-zinc tailings is 5-15mm.

[0041] experimental group In the examples and comparative examples, the consolidation material, red mud powder, and lead-zinc tailings powder were mixed with water at a water-to-solid ratio of 0.36 to prepare 40mm*40mm*40mm specimens, which were then placed in a cement standard curing chamber for curing under conditions of 20℃±3℃ and humidity greater than 95%. The specimens were cured to the specified age, and their compressive strength was tested. Heavy metal leaching toxicity tests were conducted according to the standard "Solid Waste Leaching Toxicity Leaching Method - Acetic Acid Buffer Solution Method HJ / T300-2007". The leaching concentrations of lead and zinc in the solidified body leachate are shown in the table below.

[0042] Table 1

[0043] As shown in Table 1, the 3-day and 28-day strengths of the red mud powder and lead-zinc tailings powder in this invention are both below 0.23 MPa, and their compressive strength does not increase with the extension of the curing period. The leaching concentrations of lead and zinc in the lead-zinc tailings are 1619-1622 µg / L and 10657-10676 µg / L, respectively, which are 161 times and 10.6 times the limits for Class II surface water in the Surface Water Environmental Quality Standard (GB3838-2002), posing a serious pollution risk to surface water. In the embodiments of this invention, the solidified body formed after solidification of the red mud-lead-zinc tailings base polymer consolidation material has a maximum 3-day compressive strength of 18.35 MPa and a maximum 28-day compressive strength of 50.12 MPa. High compressive strength indicates abundant hydration products in the solidified body. These hydration products cross-attach between tailings particles, increasing interparticle bonding, reducing porosity, and increasing the density of the solidified tailings body. This is beneficial for inhibiting the leaching and penetration of heavy metals and enhancing the solidification and stabilization effect on heavy metals such as lead and zinc. Furthermore, in the red mud-lead-zinc tailings base polymer solidification material prepared in this embodiment, after 28 days of curing, the lead leaching concentration was less than 7 µg / L, lower than the Class II surface water limit of 10 µg / L in the Surface Water Environmental Quality Standard (GB3838-2002), and the lead solidification rate exceeded 99.56%. After 28 days of curing, the zinc leaching concentration was less than 126 µg / L, far lower than the Class II surface water limit of 1000 µg / L in the Surface Water Environmental Quality Standard (GB3838-2002), and the zinc solidification rate exceeded 98.81%. It is evident that the red mud-lead-zinc tailings base polymer consolidation material prepared by this invention has good mechanical strength and heavy metal solidification and stabilization effects.

[0044] Compared with Example 1, the consolidation materials in Comparative Examples 3 and 4 have poor solidification and stabilization effects and cannot meet the requirements of Class II surface water in the Surface Water Environmental Quality Standard (GB3838-2002). The reason is that the mass ratio of red mud and lead-zinc tailings in Comparative Examples 3 and 4 is too high or too low, resulting in fewer hydration products, which leads to poor solidification and stabilization effects of the consolidation materials and poor mechanical properties of the solidified body.

[0045] Compared with Example 1, the solidification materials in Comparative Examples 5 and 6 have poor solidification stabilization effects and cannot meet the requirements of Class II surface water in the Surface Water Environmental Quality Standard (GB3838-2002). This indicates that using water-quenched alkaline iron slag powder, silica fume, and metakaolin as admixtures can exert a synergistic effect among the three, further improving the solidification stabilization effect of lead and zinc ions in lead-zinc tailings and the mechanical properties of the solidified body.

[0046] Compared with Example 1, the solidification material in Comparative Example 7 has a very poor solidification stabilization effect and cannot meet the requirements of Class II surface water in the Surface Water Environmental Quality Standard (GB3838-2002). The reason is that the lead-zinc tailings in Comparative Example 7 were not ground and had a large particle size, making it difficult for them to undergo a hydration reaction due to the strong alkalinity of the red mud. This ultimately resulted in the solidification material having a poor solidification stabilization effect and poor mechanical properties of the solidified body.

[0047] 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 polymer-based consolidation material for red mud-lead-zinc tailings base, characterized in that, By weight, its raw materials include: 70-80 parts of red mud-lead-zinc tailings mixture, 10-20 parts of admixture, and 5-10 parts of additives; In the red mud-lead-zinc tailings mixture, the mass ratio of red mud to lead-zinc tailings is 1:(0.25-0.5); the admixture is composed of the following components by weight percentage: 40%-50% water-quenched alkaline iron slag powder, 25%-35% silica fume, and 20%-25% metakaolin; the additive is at least one of sodium hydroxide, calcium formate, water glass, potassium hydroxide, aluminum sulfate, and sodium fluorosilicate; the uniformity of the red mud-lead-zinc tailings base polymer consolidation material is ≥90%, and the particle size is ≤10μm.

2. The red mud-lead-zinc tailings base polymer consolidation material according to claim 1, characterized in that, The red mud contains ≥35% Al2O3, and the lead-zinc tailings contain ≥50% total SiO2 and Al2O3.

3. The red mud-lead-zinc tailings base polymer consolidation material according to claim 1, characterized in that, The additive is composed of the following components by weight percentage: sodium hydroxide 40%-55%, calcium formate 3%-6%, water glass 5%-15%, potassium hydroxide 5%-15%, aluminum sulfate 15%-25%, and sodium fluorosilicate 5%-15%.

4. A solidified polymer body for red mud-lead-zinc tailings base, characterized in that, The solidified red mud-lead-zinc tailings base polymer is obtained by mixing the red mud-lead-zinc tailings base polymer solidification material according to any one of claims 1-3 with water and then curing it.

5. The solidified red mud-lead-zinc tailings base polymer according to claim 4, characterized in that, The mass ratio of the red mud-lead-zinc tailings base polymer consolidation material to water is 1:(0.3-0.4).

6. The solidified red mud-lead-zinc tailings base polymer according to claim 4, characterized in that, During the curing process, the curing temperature is 20℃±3℃ and the curing humidity is greater than 95%.

7. The solidified red mud-lead-zinc tailings base polymer according to claim 4, characterized in that, The maintenance period is 3-28 days.

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