Method for resource utilization of aluminum sulfate acidic waste residues

Abstract

The invention relates to the technical field of resource utilization, in particular to a method for resource utilization of aluminum sulfate acidic waste residues. The method comprises the following steps: mixing an alkaline substance and a sulfide to prepare an alkaline composite material; mixing and reacting the alkaline composite material and the aluminum sulfate acidic waste residue to obtain the admixture. The method comprises the following steps: mixing an alkaline composite material and aluminum sulfate acidic waste residues for reaction, and evaporating water in the waste residues by utilizing heat generated by acid-base neutralization reaction to obtain the neutral admixture. The admixture comprises the main components of calcium silicate, calcium sulphoaluminate and a small amount of unreacted aluminum, calcium and magnesium oxides, has good gelling performance, and is used for preparing concrete or cement products, so that heavy metal ions can be effectively cured, and the later strength of the material can be improved.

Description

Technical Field

[0001] This invention relates to the field of resource utilization technology, specifically to a method for the resource utilization of acidic aluminum sulfate waste residue. Background Technology

[0002] The water treatment chemical industry generates highly acidic aluminum sulfate waste during production. This waste is mainly produced by the reaction of raw materials such as bauxite and sulfuric acid. Its components mainly include silicates, alumina, and iron oxide. Some of the waste contains heavy metal ions such as lead (Pb), nickel (Ni), and chromium (Cr), as well as unreacted acidic substances. This type of waste not only contains a large amount of acidic substances such as sulfuric acid, but may also carry harmful components such as heavy metals. If not properly treated, it will cause serious harm to the ecological environment.

[0003] Currently, the main methods for disposing of acidic aluminum sulfate waste include landfilling, neutralization and stabilization, and solidification.

[0004] Direct landfill is the most basic disposal method, involving transporting waste to dedicated landfills for storage. In some cases, the waste may undergo simple dehydration or preliminary mixing with alkaline materials to reduce acidity, but this does not fundamentally alter its chemical properties. This method relies on an impermeable system to prevent contaminant migration and is considered an "end-of-pipe" technology. Landfilling permanently occupies land resources and requires continuous maintenance of the impermeable system and leachate treatment facilities, resulting in a long-term economic burden.

[0005] Neutralization and stabilization treatment involves adding lime to neutralize the waste residue, raising the pH to neutral or slightly alkaline. During this process, soluble aluminum, iron, and other metal ions form hydroxide precipitates, while some heavy metal ions co-precipitate or adsorb onto the newly formed solid phase. The neutralized product is typically dewatered by pressure filtration to form a stabilized slag before landfilling or resource recovery attempts. Neutralization requires large amounts of lime or industrial alkali, and the reaction is highly exothermic, resulting in harsh operating conditions and high operating costs. Furthermore, high concentrations of sulfate in the waste residue are difficult to remove through conventional neutralization. The metal hydroxides in the neutralization product may redissolve and release under environmental pH changes or carbonation (such as "acid reversion"), leading to secondary release of pollutants, soil salinization, and increased water mineralization.

[0006] Solidification technology involves mixing solidifying agents such as cement, lime, or polymers with waste residue, immobilizing pollutants within the solidified body through physical encapsulation and chemical bonding. This method aims to reduce the permeability of the waste residue and the leaching toxicity of pollutants, making it suitable for landfill entry standards or use as low-end building materials such as roadbed materials. However, under long-term weathering, freeze-thaw cycles, or acid precipitation erosion, the microstructure of the solidified body may be damaged, leading to the gradual leaching of heavy metals and high concentrations of sulfates, contaminating groundwater and soil. Summary of the Invention

[0007] The technical problem to be solved by the present invention is to provide a method for the resource utilization of acidic aluminum sulfate waste residue that is highly stable and not easily polluted.

[0008] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows: a method for resource utilization of aluminum sulfate acidic waste residue, wherein alkaline substances and sulfides are mixed to prepare an alkaline composite material; the alkaline composite material and aluminum sulfate acidic waste residue are mixed and reacted to obtain an admixture.

[0009] The beneficial effects of this invention are as follows: The method for resource utilization of acidic aluminum sulfate waste of this invention involves mixing and reacting an alkaline composite material with the acidic aluminum sulfate waste. The heat generated by the acid-base neutralization reaction evaporates the moisture in the waste, yielding a neutral admixture. The main components of this admixture are calcium silicate, calcium sulfoaluminate, and a small amount of unreacted aluminum, calcium, and magnesium oxides. It possesses excellent cementitious properties, and when used to prepare concrete or cement products, it can not only effectively solidify heavy metal ions but also improve the later-stage strength of the material. Detailed Implementation

[0010] To explain in detail the technical content, objectives, and effects of the present invention, the following description is provided in conjunction with the embodiments.

[0011] A method for the resource utilization of acidic aluminum sulfate waste involves mixing alkaline substances and sulfides to prepare an alkaline composite material; and then mixing the alkaline composite material with the acidic aluminum sulfate waste to obtain an admixture.

[0012] As described above, the beneficial effects of this invention are as follows: The method for resource utilization of acidic aluminum sulfate waste of this invention involves mixing and reacting an alkaline composite material with the acidic aluminum sulfate waste. The heat generated by the acid-base neutralization reaction evaporates the moisture in the waste, yielding an admixture. The main components of this admixture are calcium silicate, calcium sulfoaluminate, and a small amount of unreacted aluminum, calcium, and magnesium oxides. It possesses excellent cementitious properties and can be used in building materials, achieving the transformation of waste into treasure and comprehensive resource utilization. Using this admixture to prepare concrete or cement products not only effectively solidifies heavy metal ions but also improves the later-stage strength of the material.

[0013] The alkaline substances and sulfides in alkaline composite materials can effectively solidify the heavy metal components in acidic waste residue, thereby achieving the removal of heavy metal pollutants.

[0014] Furthermore, the alkaline composite material is ball-milled and then mixed with acidic aluminum sulfate waste residue for reaction.

[0015] As can be seen from the above description, ball milling of alkaline composite materials allows them to fully neutralize and react with acidic waste residue. During the reaction, heat is released uniformly, evaporating the residual moisture in the waste residue and saving costs for subsequent resource utilization.

[0016] Furthermore, alkaline substances include alkaline industrial byproducts and alkaline components.

[0017] As can be seen from the above description, alkaline composite materials and aluminum sulfate acidic waste residue are both classified as Class II solid waste, which further realizes the comprehensive utilization of resources.

[0018] Furthermore, alkaline industrial byproducts include at least one of papermaking sludge, refined steel slag, and carbide slag.

[0019] As described above, the main components of papermaking sludge, refined steel slag, and carbide slag are calcium carbonate, which can react fully with acidic waste residues. The reaction process releases carbon dioxide gas in situ, preventing reactants from agglomerating and improving neutralization efficiency. Furthermore, alkaline industrial byproducts all contain a certain proportion of residual alkali, which can efficiently neutralize acidic waste residues. Using calcium-based alkaline composite materials can supplement the calcium in aluminum sulfate acidic waste residues, making them suitable for subsequent resource utilization in the preparation of building materials.

[0020] Furthermore, the alkaline component includes at least one of calcium hydroxide and magnesium hydroxide.

[0021] Furthermore, by weight, the alkaline composite material comprises 80-90 parts alkaline industrial by-products, 5-10 parts alkaline components, and 5-10 parts sulfides.

[0022] Furthermore, the sulfide is at least one of sodium sulfide and ammonium sulfide.

[0023] Furthermore, the pH of the alkaline composite material is 11.5~12.5.

[0024] Furthermore, the pH of the acidic aluminum sulfate waste residue is 2.5~3.

[0025] Furthermore, the mass ratio of alkaline composite material to aluminum sulfate acidic waste residue is 1:1.8~2.2.

[0026] As can be seen from the above description, by adjusting the ratio of alkaline composite material to acidic waste residue, the proportions of aluminum, calcium, and silicon in the material after the neutralization reaction can be controlled, thereby realizing the uses of different building materials.

[0027] Furthermore, admixtures are used in the preparation of silicate cement or concrete.

[0028] As can be seen from the above description, the main components of the admixture are calcium silicate, calcium sulfoaluminate and a small amount of unreacted aluminum, calcium and magnesium oxides. It has good cementitious properties and can be used to prepare silicate cement or concrete.

[0029] Furthermore, the preparation method of silicate cement includes the following steps: determining the composition of the admixture, adding raw materials to the admixture according to the composition of silicate cement to obtain a mixture; the mixture is then successively ground and calcined to obtain silicate cement.

[0030] As can be seen from the above description, the preparation of silicate cement using the admixture of the present invention as raw material realizes the resource utilization of acidic aluminum sulfate waste residue.

[0031] Furthermore, the calcination and ripening temperature is 1350~1450℃.

[0032] Furthermore, the calcination and ripening time is 30-60 minutes.

[0033] As can be seen from the above description, a stable mineral phase can be formed after calcination and maturation at this temperature. The mineral phase composition includes tricalcium silicate, dicalcium silicate, tricalcium aluminate, and tetracalcium aluminoferrite.

[0034] In the following examples, all ingredient percentages are by weight.

[0035] Example 1 of the present invention is as follows: A method for resource utilization of acidic aluminum sulfate waste residue, wherein 80g of papermaking sludge, 10g of calcium hydroxide and 10g of sodium sulfide are thoroughly mixed and then ground in a ball mill. After passing through a 325-mesh fine sieve, an alkaline composite material with a pH of 11.5~12.5 is obtained; 200g of acidic aluminum sulfate waste residue with a pH of 2.5~3 and 100g of alkaline composite material are added to a horizontal mixing tank and thoroughly stirred for 30min, and then removed and allowed to stand for 24h to obtain the admixture.

[0036] The composition of the admixture was determined to be: 61% calcium oxide, 24% silicon dioxide, 7% aluminum oxide, and 8% other metal oxides. Raw materials were added to the admixture according to the composition of 425 silicate cement raw meal (65% calcium oxide, 22% silicon dioxide, 6% aluminum oxide, and 7% other metal oxides) to obtain a mixture. The mixture was ground to 325 mesh, then calcined and matured in a rotary kiln at 1400℃ for 30-60 minutes, and then ground again to a specific surface area of ​​approximately 350 m². 2 / kg, to obtain silicate cement.

[0037] Example 2 of the present invention is as follows: A method for resource utilization of aluminum sulfate acidic waste residue, wherein 85g of papermaking sludge, 10g of calcium hydroxide and 5g of sodium sulfide are thoroughly mixed and then ground in a ball mill and passed through a 325-mesh fine sieve to obtain an alkaline composite material with a pH of 11.5~12.5; 200g of aluminum sulfate acidic waste residue with a pH of 2.5~3 and 100g of alkaline composite material are added to a horizontal mixing tank and thoroughly stirred for 30min, and then taken out and left to stand for 24h to obtain the admixture.

[0038] The composition of the admixture was determined to be: 64% calcium oxide, 22% silicon dioxide, 6% aluminum oxide, and 8% other metal oxides. Raw materials were added to the admixture according to the composition of 425 silicate cement raw meal (65% calcium oxide, 22% silicon dioxide, 6% aluminum oxide, and 7% other metal oxides) to obtain a mixture. The mixture was ground to 325 mesh, then calcined and matured in a rotary kiln at 1400℃ for 30-60 minutes, and then ground again to a specific surface area of ​​approximately 350 m². 2 / kg, to obtain silicate cement.

[0039] Example 3 of the present invention is: a method for resource utilization of aluminum sulfate acidic waste residue, wherein 85g of papermaking white mud, 5g of calcium hydroxide and 10g of sodium sulfide are thoroughly mixed and then ground in a ball mill. After passing through a 325-mesh fine sieve, an alkaline composite material with a pH of 11.5~12.5 is obtained; 200g of aluminum sulfate acidic waste residue with a pH of 2.5~3 and 100g of alkaline composite material are added to a horizontal mixing tank and thoroughly stirred for 30min, and then taken out and left to stand for 24h to obtain the admixture.

[0040] The composition of the admixture was determined to be: calcium oxide 63%, silicon dioxide 24%, aluminum oxide 6%, and other metal oxides 7%. Raw materials were added to the admixture according to the composition of 425 silicate cement raw meal (calcium oxide 65%, silicon dioxide 22%, aluminum oxide 6%, and other metal oxides 7%) to obtain a mixture. The mixture was ground to 325 mesh, then calcined and matured in a rotary kiln at 1400℃ for 30-60 minutes, and then ground again to a specific surface area of ​​approximately 350 m². 2 / kg, to obtain silicate cement.

[0041] Example 4 of the present invention is: a method for resource utilization of acidic aluminum sulfate waste residue, wherein 85g of refined steel slag, 5g and 10g of sodium sulfide are thoroughly mixed, then ground in a ball mill, and after passing through a 325-mesh fine sieve, an alkaline composite material with a pH of 11.5~12.5 is obtained; 200g of acidic aluminum sulfate waste residue with a pH of 2.5~3 and 100g of alkaline composite material are added to a horizontal mixing tank and thoroughly stirred for 30min, then removed and left to stand for 24h to obtain the admixture.

[0042] The composition of the admixture was determined to be: 61% calcium oxide, 24% silicon dioxide, 6% aluminum oxide, and 9% other metal oxides. Raw materials were added to the admixture according to the composition of 425 silicate cement raw meal (65% calcium oxide, 22% silicon dioxide, 6% aluminum oxide, and 7% other metal oxides) to obtain a mixture. The mixture was ground to 325 mesh, then calcined and matured in a rotary kiln at 1400℃ for 30-60 minutes, and then ground again to a specific surface area of ​​approximately 350 m². 2 / kg, to obtain silicate cement.

[0043] Example 5 of the present invention is: a method for resource utilization of aluminum sulfate acidic waste residue, wherein 90g of carbide slag, 5g of magnesium hydroxide and 5g of ammonium sulfide are thoroughly mixed and then ground in a ball mill and passed through a 325-mesh fine sieve to obtain an alkaline composite material with a pH of 11.5~12.5; 200g of aluminum sulfate acidic waste residue with a pH of 2.5~3 and 100g of alkaline composite material are added to a horizontal mixing tank and thoroughly stirred for 30min, and then taken out and left to stand for 24h to obtain an admixture.

[0044] The composition of the admixture was determined to be: 65% calcium oxide, 22% silicon dioxide, 7% aluminum oxide, and 6% other metal oxides. Raw materials were added to the admixture according to the composition of 425 silicate cement raw meal (65% calcium oxide, 22% silicon dioxide, 6% aluminum oxide, and 7% other metal oxides) to obtain a mixture. The mixture was ground to 325 mesh, then calcined and matured in a vertical kiln at 1350℃ for 60 minutes, and then ground again to a specific surface area of ​​approximately 350 m². 2 / kg, to obtain silicate cement.

[0045] Example 6 of the present invention is as follows: A method for resource utilization of acidic aluminum sulfate waste residue, wherein 44g of carbide slag, 40g of refined steel slag, 4g of calcium hydroxide, 4g of magnesium hydroxide and 8g of ammonium sulfide are thoroughly mixed, and then ground in a ball mill and passed through a 325-mesh fine sieve to obtain an alkaline composite material with a pH of 11.5~12.5; 200g of acidic aluminum sulfate waste residue with a pH of 2.5~3 and 100g of alkaline composite material are added to a horizontal mixing tank and thoroughly stirred for 30min, and then taken out and left to stand for 24h to obtain the admixture.

[0046] The composition of the admixture was determined to be: calcium oxide 61%, silicon dioxide 22%, aluminum oxide 8%, and other metal oxides 9%. Raw materials were added to the admixture according to the composition of 425 silicate cement raw meal (calcium oxide 65%, silicon dioxide 22%, aluminum oxide 6%, and other metal oxides 7%) to obtain a mixture. The mixture was ground to 325 mesh, then calcined and matured in a rotary kiln at 1450℃ for 30 minutes, and then ground again to a specific surface area of ​​approximately 350 m². 2 / kg, to obtain silicate cement.

[0047] Cement performance testing; The initial setting time and final setting time of cement in Examples 1 to 6 were tested according to the standard method of GB 175-2023; The compressive strength of the cement in Examples 1 to 6 was tested according to the standard method of GB 175-2023, and the test results are shown in Table 1.

[0048] Table 1

[0049] In summary, the method for resource utilization of acidic aluminum sulfate waste provided by this invention has the following advantages: 1. Using alkaline composite materials and acidic aluminum sulfate residue as raw materials, both of which are Class II solid wastes, the mixed residue becomes neutral after neutralization and can be used in building materials, realizing the transformation of waste into treasure and comprehensive utilization of resources; 2. The main component of the alkaline composite material is calcium carbonate. During the uniform mixing process with the acidic aluminum sulfate waste residue, a neutralization reaction occurs, releasing carbon dioxide gas in situ. This can prevent the aluminum sulfate acidic waste residue and the alkaline composite material from agglomerating and clumping during the reaction process, thereby improving the neutralization reaction efficiency. 3. The alkaline composite material is ball-milled to fully neutralize and react with the acidic waste residue. During the reaction, heat is released evenly to evaporate the residual moisture in the waste residue, saving costs for subsequent resource utilization. 4. By adjusting the ratio of alkaline composite materials to acidic waste residue, the proportions of aluminum, calcium, and silicon in the materials after the neutralization reaction can be controlled, thereby enabling the use of different building materials. 5. The alkaline components and sulfides introduced into the alkaline composite material can effectively solidify the heavy metal components in the acidic waste residue, thereby achieving the removal of heavy metal pollutants.

[0050] The above description is merely an embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent modifications made using the present invention specification, or direct or indirect applications in related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A method for the resource utilization of acidic aluminum sulfate waste residue, characterized in that, An alkaline composite material is prepared by mixing an alkaline substance and a sulfide; the alkaline composite material is then mixed with acidic aluminum sulfate waste residue to obtain an admixture.

2. The method for resource utilization of acidic aluminum sulfate waste residue according to claim 1, characterized in that, The alkaline substance includes alkaline industrial byproducts and alkaline components.

3. The method for resource utilization of acidic aluminum sulfate waste residue according to claim 2, characterized in that, The alkaline industrial byproducts include at least one of papermaking sludge, refined steel slag, and carbide slag.

4. The method for resource utilization of acidic aluminum sulfate waste residue according to claim 2, characterized in that, The alkaline component includes at least one of calcium hydroxide and magnesium hydroxide.

5. The method for resource utilization of acidic aluminum sulfate waste residue according to claim 2, characterized in that, By weight, the alkaline composite material comprises 80-90 parts alkaline industrial by-products, 5-10 parts alkaline components, and 5-10 parts sulfides.

6. The method for resource utilization of acidic aluminum sulfate waste residue according to claim 1, characterized in that, The sulfide is at least one of sodium sulfide and ammonium sulfide.

7. The method for resource utilization of acidic aluminum sulfate waste residue according to claim 1, characterized in that, The pH of the alkaline composite material is 11.5~12.

5.

8. The method for resource utilization of acidic aluminum sulfate waste residue according to claim 1, characterized in that, The pH of the acidic aluminum sulfate waste residue is 2.5~3.

9. The method for resource utilization of acidic aluminum sulfate waste residue according to claim 1, characterized in that, The mass ratio of the alkaline composite material to the aluminum sulfate acidic waste residue is 1:1.8~2.

2.

10. The method for resource utilization of acidic aluminum sulfate waste residue according to claim 1, characterized in that, The admixture is used to prepare silicate cement or concrete.

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