CN117142834B - Method for preparing high-strength baking-free brick by utilizing co-treatment of waste incineration fly ash and phosphogypsum yard leachate - Google Patents

Abstract

The invention discloses a method for preparing high-strength burn-free bricks by co-processing waste incineration fly ash and phosphogypsum yard leachate. It includes the following steps: (1) Mix light-burned magnesium oxide and waste incineration fly ash, stir evenly, and obtain magnesium-mixed fly ash powder; (2) Mix sepiolite and coal gangue, and grind them into powder to obtain active powder; (3) ) Mix water glass, active powder and magnesium-mixed fly ash powder, and stir evenly to obtain active magnesium-mixed ash; (4) Mix the phosphogypsum yard leachate and active magnesia-mixed ash, stir evenly, put it into the mold, cure, and remove it. Mold, and after standing, high-strength non-burning bricks can be obtained. The preparation process of the method of the present invention is simple, the required raw materials are widely available and easily available, the maximum uniaxial compressive strength of the prepared brick structure can reach 36.58MPa, and the heavy metal leaching concentrations meet the "Technical Specifications for the Control of Fly Ash Pollution from Domestic Waste Incineration" (HJ1134) ‑2020) pollution control requirements.

Description

A method to prepare high-quality materials by co-processing waste incineration fly ash and phosphogypsum yard leachate Methods to avoid burning bricks

Technical field

The invention belongs to the field of harmless disposal of hazardous wastes, and in particular relates to a method for preparing high-strength burn-free bricks by co-processing waste incineration fly ash and phosphogypsum yard leachate.

Background technique

Phosphogypsum is a large by-product produced during the production of phosphoric acid and phosphate fertilizers using phosphate rock as raw material. In the phosphogypsum stockyard, a large amount of phosphogypsum leachate is easily produced. Phosphogypsum leachate is acidic and contains high concentrations of inorganic salts (such as sulfates, phosphates, silicates, fluorides, chlorides), ammonia nitrogen pollutants, heavy metal pollutants, etc., which has certain environmental hazards. The rich phosphorus in the phosphogypsum leachate can easily cause eutrophication of the water body, causing algae blooms and algal blooms, making the water body depleted and oxidized, causing serious harm to the water body ecology. If the phosphorus element in the phosphogypsum leachate seeps into the soil, it will cause the phosphorus content in the soil to be too high. Long-term accumulation will lead to soil acidification, affect the growth of crops, and reduce the value of land use. Eutrophication of water bodies and acidification of soil will both lead to the reduction of biodiversity and affect the stability and sustainable development of ecosystems. The fluorine-containing pollutants in phosphogypsum leachate have a comprehensive impact on the ecological environment, including impacts on aquatic life, terrestrial life and aerial life. High concentrations of fluoride can lead to a reduction in biological populations and destroy ecological balance. It may also enter organisms through the food chain and affect the stability of biological genetic materials.

Waste incineration fly ash is particulate matter collected through cloth bags after rapid cooling and deacidification of waste incineration flue gas. Waste incineration fly ash not only contains heavy metals and dioxin pollutants, but also contains a large amount of inorganic chlorine salts. Waste incineration fly ash is environmentally toxic and carcinogenic, and it is difficult to process. It usually requires a long disposal process to achieve pyrolysis of dioxin, heavy metal separation, and chlorine salt removal in waste incineration fly ash. The existing disposal technology not only has a long process chain and low disposal efficiency, but also cannot truly realize the resource utilization of waste incineration fly ash.

Therefore, a method of co-processing waste incineration fly ash and phosphogypsum stockpile leachate was developed to achieve resource utilization of waste incineration fly ash and phosphogypsum stockpile leachate, and to improve the utilization of waste incineration fly ash and phosphogypsum stockpile leachate. The disposal has important reference significance.

Contents of the invention

Purpose of the invention: The purpose of the present invention is to provide a method for preparing high-strength burn-free bricks by co-processing waste incineration fly ash and phosphogypsum yard leachate.

Technical solution: The invention provides a method for preparing high-strength burn-free bricks by co-processing waste incineration fly ash and phosphogypsum yard leachate, including the following steps:

(1) Mix light-burned magnesium oxide and waste incineration fly ash, stir evenly, and obtain magnesium-mixed fly ash powder;

(2) Mix sepiolite and coal gangue and grind them into powder to obtain active powder;

(3) Mix water glass, active powder and magnesium-doped fly ash powder, and stir evenly to obtain active magnesium-doped ash;

(4) Mix the phosphogypsum stockpile leachate and active magnesium-doped ash, stir evenly, put it into the mold, cure it, demould it, and then let it stand to obtain high-strength non-burning bricks.

Further, the mass ratio of light-burned magnesium oxide and waste incineration fly ash described in step (1) is 5~15:100.

Further, the mass ratio of sepiolite and gangue described in step (2) is 10~30:100.

Further, the mass ratio of water glass, active powder and magnesium-doped fly ash powder described in step (3) is 2.5~12.5:20~40:100.

Further, the solid ratio of the phosphogypsum stockpile leachate and the active magnesia-doped ash liquid described in step (4) is 0.25~0.55:1mL/g.

Further, the curing time described in step (4) is 12 to 36 hours.

Further, the resting time described in step (4) is 14 to 28 days.

The invention also provides high-strength unfired bricks prepared by the above method.

Reaction mechanism: After mixing the phosphogypsum yard leachate and active magnesia-doped ash, the calcium-based substances in the active magnesium-doped ash and light-burned magnesium oxide (calcium oxide, basic calcium chloride, calcium hydroxide, etc.) Reacts with phosphates, sulfates, and fluorides in the phosphogypsum stockpile leachate to produce calcium fluoride, dihydrate gypsum, magnesium hydroxide, magnesium sulfate-magnesium oxide gel, hydroxyapatite, and fluorinated hydroxyapatite. , potassium magnesium phosphate hexahydrate and other stable mineral mixtures to achieve the stabilization of phosphates and fluorides. Heavy metal pollutants in fly ash can be stabilized in mineral phases such as magnesium sulfate-magnesium oxide gel, hydroxyapatite, fluorinated hydroxyapatite, potassium magnesium phosphate hexahydrate, etc. through ion exchange and potential balance. At the same time, under the action of multiple alkali excitations of alkaline substances in water glass, leachate phosphate, and fly ash, the aluminosilicates in sepiolite and coal gangue undergo alkali dissolution to form magnesium silicate and aluminosilicate gels. Magnesium silicate and aluminosilicate gel further react with light-burned magnesium oxide and calcium-based substances to generate a gel phase blended with magnesium silicate-magnesium oxide gel and geopolymer. The gel phase is mixed and wrapped with a stable mineral mixture, which gradually hardens during the curing process to form a dense structure. Therefore, heavy metal contaminants in fly ash are not only stabilized in a stable mineral mixture but also encased in a dense geopolymer structure.

Beneficial effects: Compared with the existing technology, the present invention has the following outstanding and significant advantages: the preparation process of the method of the present invention is simple, the sources of required raw materials are wide and easy to obtain, and the maximum uniaxial compressive strength of the prepared brick structure can reach 36.58MPa. , the heavy metal leaching concentrations all meet the pollution control requirements of the "Technical Specifications for Pollution Control of Fly Ash from Domestic Waste Incineration" (HJ1134-2020).

Description of drawings

Figure 1 is a flow chart of the method of the present invention.

Detailed ways

The technical solution of the present invention will be further described below with reference to the accompanying drawings.

Waste incineration fly ash: taken from the Second Domestic Waste Incineration Power Plant in Changshu, Jiangsu, mainly including 36.2% CaO, 23.9% Cl, 11.0% SO ₃ , 11.6% Na ₂ O, 6.33% K ₂ O, 4.38% SiO ₂ , 1.40 %Fe ₂ O ₃ , 1.25%Al ₂ O ₃ and other components (inevitable impurities and loss on ignition).

Light burned magnesium oxide: from Nantong Runfeng Petrochemical Co., Ltd., mainly including 96.04% MgO, 0.75% SiO ₂ , 0.46% CaO, 0.11% Fe ₂ O ₃ and other ingredients (inevitable impurities and loss on ignition).

Coal gangue: from Shanxi Xishan Coal and Electricity Co., Ltd., mainly including 46.87% SiO ₂ , 33.51% Al ₂ O ₃ , 12.04% Fe ₂ O ₃ , 2.72% CaO, 2.36K ₂ O, 1.37% TiO ₂ and other components ( unavoidable impurities and loss on ignition).

Sepiolite: from Neixiang County Hongyang Sepiolite Co., Ltd., its general formula is (Si ₁₂ Mg ₈ O ₃₀ )(OH) ₄ (OH ₂ ) ₄ •8H ₂ O.

Water glass: purchased from Aladdin Reagent Network, CAS number: 84992-49-4, product number: S598453-250ml.

Phosphogypsum stockpile leachate: Phosphogypsum stockpile leachate was obtained by sampling from the on-site collection pool of the phosphogypsum stockpile in Xifeng County, Guizhou.

Example 1 Effect of mass comparison of light-burned magnesium oxide and waste incineration fly ash on the prepared high-strength unburned bricks and leaching toxicity

Weigh light burned magnesium oxide and waste incineration fly ash respectively according to the mass ratio of 2.5:100, 3:100, 4:100, 5:100, 10:100, 15:100, 17:100, 19:100 and 20:100. , stir evenly to obtain magnesium-doped fly ash powder. Weigh sepiolite and coal gangue respectively according to the mass ratio of 10:100, mix them, and grind them into powder to obtain active powder. Weigh water glass, active powder and magnesium-doped fly ash powder respectively according to the mass ratio of 2.5:20:100, mix and stir evenly to obtain active magnesium-doped ash. Weigh the phosphogypsum stockpile leachate and active magnesia-doped ash respectively according to the liquid-to-solid ratio of 0.25:1mL/g, mix them, stir evenly, put them into the mold, cure them for 12 hours, demold them, and let them stand for 14 days to obtain high-strength non-burning bricks.

Compressive strength test: The compressive strength test of the high-strength unfired brick prepared by the present invention is carried out in accordance with the "Concrete Solid Brick" (GB/T 21144-2007) standard.

Preparation of leachate: The leachate for preparing high-strength non-burning bricks according to the "Horizontal Oscillation Method for Leaching Toxicity of Solid Waste" (HJ 557-2010).

Determination of the concentration of heavy metal ions in the leachate of high-strength bricks: The concentrations of lead and cadmium pollutants in the leachate were measured in accordance with the provisions of "Water Quality Determination of 32 Elements - Inductively Coupled Plasma Emission Spectrometry" (HJ 776-2015). The total chromium in the leaching solution of high-strength bricks was measured in accordance with the provisions of "Determination of Water Quality Chromium - Flame Atomic Absorption Spectrophotometry" (HJ 757-2015). The results of this example are shown in Table 1.

Table 1 The effect of the mass comparison of light-burned magnesium oxide and waste incineration fly ash on the prepared high-strength unfired bricks and leaching toxicity

It can be seen from Table 1 that when the mass ratio of light-burned magnesium oxide to garbage incineration fly ash is less than 5:100 (for example, in Table 1, the mass ratio of light-burned magnesium oxide to garbage incineration fly ash = 4:100, 3:100, 2.5: 100 and lower ratios not listed in Table 1), the added amount of light-burned magnesium oxide is small, the material reaction is unbalanced, and the production of highly active gelling products is reduced, resulting in the heavy metal leaching concentration of the prepared high-strength unfired bricks increasing with the light-burned magnesium oxide. The uniaxial compressive strength of the prepared high-strength unburned bricks decreases significantly as the mass ratio of light-burned magnesium oxide to garbage incineration fly ash decreases. When the mass ratio of light-burned magnesium oxide to garbage incineration fly ash is equal to 5~15:100 (as in Table 1, the mass ratio of light-burned magnesium oxide to garbage incineration fly ash = 5:100, 10:100, 15:100) , after mixing the phosphogypsum stockpile leachate and active magnesia-doped ash, the calcium-based substances and light-burned magnesium oxide (calcium oxide, basic calcium chloride, calcium hydroxide, etc.) and phosphorus in the active magnesia-doped ash are mixed during the mixing process. Phosphate, sulfate, and fluoride in the gypsum yard leachate react to form calcium fluoride, dihydrate gypsum, magnesium hydroxide, magnesium sulfate-magnesium oxide gel, hydroxyapatite, fluorinated hydroxyapatite, and hexafluoride. Stabilizing mineral mixtures such as potassium and magnesium phosphates in water, thereby stabilizing phosphates and fluorides. Heavy metal pollutants in fly ash can be stabilized in mineral phases such as magnesium sulfate-magnesium oxide gel, hydroxyapatite, fluorinated hydroxyapatite, potassium magnesium phosphate hexahydrate, etc. through ion exchange and potential balance. In the end, the heavy metal leaching concentration of the prepared high-strength unfired bricks was less than or equal to 0.01mg/L, and the strength of the high-strength unfired bricks was higher than 25MPa. When the mass ratio of light-burned magnesium oxide to garbage incineration fly ash is greater than 15:100 (as in Table 1, the mass ratio of light-burned magnesium oxide to garbage incineration fly ash = 17:100, 19:100, 20:100 and Table 1 Higher ratios not listed in ), excessive addition of light-burned magnesium oxide, unbalanced material reaction, resulting in heavy metal leaching concentration of the prepared high-strength unburned bricks significantly increases as the mass ratio of light-burned magnesium oxide to garbage incineration fly ash further increases. , and the uniaxial compressive strength of the prepared high-strength unfired bricks decreases significantly as the mass ratio of light-burned magnesium oxide to waste incineration fly ash further increases.

Therefore, in general, when the mass ratio of light-burned magnesium oxide to waste incineration fly ash is equal to 5~15:100, it is most beneficial to the performance of the prepared high-strength unburned bricks.

Example 2 Effect of the mass ratio of sepiolite and coal gangue on the prepared high-strength unfired bricks and their leaching toxicity

Weigh light-burned magnesium oxide and waste incineration fly ash respectively according to a mass ratio of 15:100, stir them evenly, and obtain magnesium-doped fly ash powder. Weigh sepiolite and gangue respectively according to the mass ratio of 2.5:100, 5:100, 7.5:100, 10:100, 20:100, 30:100, 35:100, 40:100 and 45:100, mix and grind into powder to obtain active powder. Weigh water glass, active powder and magnesium-doped fly ash powder respectively according to the mass ratio of 7.5:30:100, mix and stir evenly to obtain active magnesium-doped ash. Weigh the phosphogypsum stockpile leachate and active magnesia-doped ash respectively according to the liquid-to-solid ratio of 0.4:1mL/g, mix them, stir evenly, put them into the mold, cure them for 24 hours, demold them, and let them stand for 20 days to obtain high-strength non-burning bricks.

The compressive strength test, leachate preparation, and determination of the concentration of heavy metal ions in the leachate of high-strength bricks are all the same as in Example 1. The results of this example are shown in Table 2.

Table 2 Effects of the mass ratio of sepiolite and coal gangue on the prepared high-strength unfired bricks and their leaching toxicity

It can be seen from Table 2 that when the mass ratio of sepiolite and coal gangue is less than 10:100 (for example, in Table 2, the mass ratio of sepiolite and coal gangue = 7.5:100, 5:100, 2.5:100, and when the mass ratio is not listed in Table 2 (lower ratio), the added amount of sepiolite is less, the material reaction is unbalanced, and the production of highly active gelling products is reduced, resulting in the heavy metal leaching concentration of the prepared high-strength unburned bricks being significantly reduced with the mass ratio of sepiolite and coal gangue. increases, while the uniaxial compressive strength of the prepared high-strength unfired bricks decreases significantly as the mass ratio of sepiolite and coal gangue decreases. When the mass ratio of sepiolite and gangue is equal to 10~30:100 (as in Table 2, the mass ratio of sepiolite and gangue = 10:100, 20:100, 30:100), in water glass and leachate phosphoric acid Under the action of multiple alkali excitations of alkaline substances in salt and fly ash, the aluminosilicates in sepiolite and coal gangue undergo alkali dissolution to form magnesium silicate and aluminosilicate gels. Magnesium silicate and aluminosilicate gels form The gel further reacts with light-burned magnesium oxide and calcium-based substances to form a gel phase blended with magnesium silicate-magnesium oxide gel and geopolymer. The gel phase is mixed and wrapped with a stable mineral mixture, which gradually hardens during the curing process to form a dense structure. In the end, the heavy metal leaching concentration of the prepared high-strength unfired bricks was lower than 0.005mg/L, and the strength of the high-strength unfired bricks was higher than 30MPa. When the mass ratio of sepiolite to coal gangue is greater than 30:100 (such as in Table 2, the mass ratio of sepiolite to coal gangue = 10:100, 20:100, 30:100 and higher ratios not listed in Table 2) , too much sepiolite is added, and the material reaction is unbalanced, resulting in the heavy metal leaching concentration of the prepared high-strength unburned bricks increasing significantly with the further increase in the mass ratio of sepiolite and coal gangue, while the uniaxial compressive strength of the prepared high-strength unburned bricks The mass ratio of sepiolite to coal gangue decreases significantly as the mass ratio further increases.

Therefore, in general, when the mass ratio of sepiolite and coal gangue is equal to 10~30:100, it is most beneficial to the performance of the prepared high-strength unfired bricks.

Example 3 Effect of mass ratio of water glass, active powder and magnesium-doped fly ash powder on the prepared high-strength unfired bricks and leaching toxicity

Weigh light-burned magnesium oxide and waste incineration fly ash respectively according to a mass ratio of 15:100, stir them evenly, and obtain magnesium-doped fly ash powder. Weigh sepiolite and coal gangue respectively according to the mass ratio of 30:100, mix them, and grind them into powder to obtain active powder. According to the mass ratio 1:20:100, 1.5:20:100, 2:20:100, 2.5:12.5:100, 2.5:15:100, 2.5:17.5:100, 2.5:20:100, 7.5:20:100 , 12.5:20:100, 2.5:30:100, 7.5:30:100, 12.5:30:100, 2.5:40:100, 7.5:40:100, 12.5:40:100, 12.5:45:100, 12.5 :50:100, 12.5:55:100, 15:40:100, 17.5:40:100, 20:40:100 Weigh water glass, active powder and magnesium-mixed fly ash powder respectively, mix and stir evenly to obtain active mixed powder. Magnesium ash. Weigh the phosphogypsum stockpile leachate and activated magnesia-doped ash respectively according to the liquid-to-solid ratio of 0.55:1mL/g, mix them, stir evenly, put them into the mold, cure them for 36 hours, demold them, and let them stand for 28 days to obtain high-strength non-burning bricks.

The compressive strength test, leachate preparation, and determination of the concentration of heavy metal ions in the leachate of high-strength bricks are all the same as in Example 1. The results of this example are shown in Table 3.

Table 3 The effect of the mass ratio of water glass, active powder and magnesium-doped fly ash powder on the prepared high-strength unfired bricks and their leaching toxicity

It can be seen from Table 3 that when the mass ratio of water glass, active powder and magnesium mixed with fly ash powder is less than 2.5:20:100 (for example, in Table 3, the mass ratio of water glass, active powder and magnesium mixed with fly ash powder = 2:20: 100, 1.5:20:100, 1:20:100, 2.5:17.5:100, 2.5:15:100, 2.5:12.5:100 and lower ratios not listed in Table 3), add water glass and active powder The amount is small, the material reaction is unbalanced, and the production of highly active gelling products is reduced, resulting in a significant increase in the heavy metal leaching concentration of the prepared high-strength burn-free bricks as the mass ratio of water glass, active powder and magnesium-doped fly ash powder decreases. The uniaxial compressive strength of high-strength unfired bricks significantly decreases as the mass ratio of water glass, active powder and magnesium-doped fly ash powder decreases. When the mass ratio of water glass, active powder and magnesium-doped fly ash powder is equal to 2.5~12.5:20~40:100 (as in Table 3, the mass ratio of water glass, active powder and magnesium-doped fly ash powder = 2.5:20:100 ) , under the action of multiple alkali excitations of alkaline substances in water glass, leachate phosphate, and fly ash, the aluminosilicates in sepiolite and coal gangue undergo alkali dissolution to form magnesium silicate and aluminosilicate gels, silicon Magnesium silicate and aluminosilicate gel further react with light-burned magnesium oxide and calcium-based substances to generate a gel phase blended with magnesium silicate-magnesium oxide gel and geopolymer. The gel phase is mixed and wrapped with a stable mineral mixture, which gradually hardens during the curing process to form a dense structure. Therefore, heavy metal contaminants in fly ash are not only stabilized in a stable mineral mixture but also encased in a dense geopolymer structure. In the end, the heavy metal leaching concentration of the prepared high-strength unfired bricks was lower than 0.002mg/L, and the strength of the high-strength unfired bricks was higher than 33MPa. When the mass ratio of water glass, active powder and magnesium mixed with fly ash powder is greater than 12.5:40:100 (for example, in Table 3, the mass ratio of water glass, active powder and magnesium mixed with fly ash powder = 12.5:45:100, 12.5:50 :100, 12.5:55:100, 15:40:100, 17.5:40:100, 20:40:100 and higher ratios not listed in Table 3), too much water glass and active powder are added, and the material reaction is unbalanced , causing the heavy metal leaching concentration of the prepared high-strength unfired bricks to significantly increase as the mass ratio of water glass, active powder and magnesium-doped fly ash powder further increases, while the uniaxial compressive strength of the prepared high-strength unfired bricks increases with the increase of the water glass, active powder and magnesium-doped fly ash powder. , the mass ratio of active powder and magnesium-doped fly ash powder decreases significantly with further increase.

Therefore, in general, when the mass ratio of water glass, active powder and magnesium-doped fly ash powder is equal to 2.5~12.5:20~40:100, it is most beneficial to the performance of the prepared high-strength unfired bricks.

Comparison Example Comparison of high-strength unfired bricks and leaching toxicity achieved by different comparison processes

The process of the present invention: Weigh light-burned magnesium oxide and garbage incineration fly ash respectively according to a mass ratio of 15:100, stir them evenly, and obtain magnesium-doped fly ash powder. Weigh sepiolite and coal gangue respectively according to the mass ratio of 30:100, mix them, and grind them into powder to obtain active powder. Weigh water glass, active powder and magnesium-doped fly ash powder respectively according to the mass ratio of 12.5:40:100, mix and stir evenly to obtain active magnesium-doped ash. Weigh the phosphogypsum stockpile leachate and activated magnesia-doped ash respectively according to the liquid-to-solid ratio of 0.55:1mL/g, mix them, stir evenly, put them into the mold, cure them for 36 hours, demold them, and let them stand for 28 days to obtain high-strength non-burning bricks.

Comparative process 1: Weigh sepiolite and gangue respectively according to the mass ratio of 30:100, mix and grind them into powder to obtain active powder. Weigh water glass, active powder and waste incineration fly ash respectively according to the mass ratio of 12.5:40:100, mix and stir evenly to obtain active ash. Weigh the phosphogypsum stockpile leachate and activated ash respectively according to the liquid-to-solid ratio of 0.55:1mL/g, mix them, stir evenly, put them into the mold, cure for 36 hours, demould, and wait for 28 days to obtain high-strength non-burning bricks.

Comparison process 2: Weigh light-burned magnesium oxide and garbage incineration fly ash respectively according to the mass ratio of 15:100, stir them evenly, and obtain magnesium-doped fly ash powder. Grind coal gangue into powder. Weigh water glass, coal gangue powder and magnesium-mixed fly ash powder respectively according to the mass ratio of 12.5:40:100, mix and stir evenly to obtain mixed ash. Weigh the phosphogypsum stockpile leachate and activated magnesia-doped ash respectively according to the liquid-to-solid ratio of 0.55:1mL/g, mix them, stir evenly, put them into the mold, cure them for 36 hours, demold them, and let them stand for 28 days to obtain high-strength non-burning bricks.

Comparison process 3: Weigh light-burned magnesium oxide and garbage incineration fly ash respectively according to the mass ratio of 15:100, stir them evenly, and obtain magnesium-doped fly ash powder. Grind the sepiolite into powder. Weigh sodium silicate, sepiolite powder and magnesium-doped fly ash powder respectively according to the mass ratio of 12.5:40:100, mix and stir evenly to obtain sepiolite-doped magnesium ash. According to the liquid-to-solid ratio of 0.55:1mL/g, weigh the phosphogypsum stockpile leachate and seafoam-mixed magnesium ash respectively, mix them, stir evenly, put them into the mold, cure them for 36 hours, demold them, and let them stand for 28 days to obtain high-strength unburned bricks.

Comparison process 4: Weigh light-burned magnesium oxide and garbage incineration fly ash respectively according to the mass ratio of 15:100, stir them evenly, and obtain magnesium-doped fly ash powder. Weigh sepiolite and coal gangue respectively according to the mass ratio of 30:100, mix them, and grind them into powder to obtain active powder. Weigh water glass, active powder and magnesium-doped fly ash powder respectively according to the mass ratio of 12.5:40:100, mix and stir evenly to obtain active magnesium-doped ash. Weigh water and active magnesia-doped ash respectively according to the liquid-to-solid ratio of 0.55:1mL/g, mix them, stir evenly, put them into the mold, cure them for 36 hours, demold them, and let them stand for 28 days to obtain high-strength non-burning bricks.

The compressive strength test, leachate preparation, and determination of the concentration of heavy metal ions in the leachate of high-strength bricks are all the same as in Example 1. The results of this example are shown in Table 4.

Table 4 Comparison of high-strength unfired bricks and leaching toxicity achieved by different comparative processes

It can be seen from Table 4 that the uniaxial compressive strength of the unfired bricks prepared by the process of the present invention is significantly higher than that of Comparative Process 1, Comparative Process 2, Comparative Process 3, and Comparative Process 4, and is higher than the sum of the four. The heavy metal leaching toxicity of the unfired bricks prepared by the process of the present invention is much lower than that of the unfired bricks prepared by Comparative Process 1, Comparative Process 2, Comparative Process 3, and Comparative Process 4.

Claims (4)

1. A method for preparing high-strength burn-free bricks by co-processing waste incineration fly ash and phosphogypsum yard leachate, which is characterized by comprising the following steps: (1) Mix light-burned magnesium oxide and waste incineration fly ash, stir evenly, and obtain magnesium-mixed fly ash powder; The mass ratio of the light-burned magnesium oxide to waste incineration fly ash is 5~15:100; (2) Mix sepiolite and coal gangue and grind them into powder to obtain active powder; The mass ratio of sepiolite and coal gangue is 10~30:100; (3) Mix water glass, active powder and magnesium-doped fly ash powder, and stir evenly to obtain active magnesium-doped ash; The mass ratio of water glass, active powder and magnesium-doped fly ash powder is 2.5~12.5:20~40:100; (4) Mix the phosphogypsum stockpile leachate and active magnesia-doped ash, stir evenly, put it into the mold, cure it, demould it, and then let it stand to obtain the high-strength non-burning brick; The solid ratio of the phosphogypsum stockpile leachate and active magnesia-doped ash liquid is 0.25~0.55:1mL/g. 2. The method for preparing high-strength burn-free bricks by utilizing the co-processing of garbage incineration fly ash and phosphogypsum yard leachate according to claim 1, characterized in that the curing time described in step (4) is 12 to 36 hours. . 3. The method of preparing high-strength burn-free bricks by utilizing the co-processing of garbage incineration fly ash and phosphogypsum yard leachate according to claim 1, characterized in that the standing time in step (4) is 14 to 28 sky. 4. A high-strength unfired brick prepared by the method of any one of claims 1 to 3.