Method for hot-stewing and iron extraction of steel slag and building material by waste heat reduction of high-water-content iron-containing solid waste

Abstract

This invention belongs to the field of solid waste resource utilization technology, specifically disclosing a method for the thermal quenching and iron extraction from high-moisture, iron-containing solid waste using waste heat, including the following steps: S1: Mixing iron tailings slurry and / or red mud slurry with carbon powder in a specific ratio to obtain a mixed slurry; S2: Pouring molten steel slag into a quenching tank; S3: Spraying the mixed slurry onto the surface of the molten steel slag; S4: After the water in the mixed slurry evaporates, crushing and turning the steel slag to form a steel slag mixture; S5: Repeating S2-S4 until the steel slag mixture reaches the rated capacity of the quenching tank, then covering the quenching tank; S6: Injecting water into the quenching tank for quenching; S7: Crushing the quenched steel slag mixture to extract metallic iron particles; S8: Ball milling the remaining material to extract iron concentrate; S9: Using the remaining tailings as raw material for building materials. This method achieves the synergistic treatment of multi-source solid waste and the secondary utilization of waste heat from molten steel slag and slurry wastewater.

Description

Technical Field

[0001] The invention belongs to the technical field of solid waste resource utilization, and in particular relates to a method for hot-stewing steel slag to extract iron and convert it into building materials by reducing high-water and iron-containing solid waste with waste heat. Background Art

[0002] The statements herein merely provide background information related to the present invention and do not necessarily constitute prior art.

[0003] Steel slag is a by-product of converter steelmaking. Hot stewing is one of the main methods for treating steel slag. It has the advantages of wide application range, good stability of treated steel slag, high pulverization rate, and sufficient slag-iron separation. The hot stewing method of steel slag (also known as "stewing slag") is to pour the molten steel slag into the stewing slag pool, seal the stewing slag pool with a hot stewing device cover, spray water inside, and the high-temperature steel slag will produce a large amount of saturated steam when it meets water. The steel slag will be crushed and pulverized under the high pressure formed by the steam. The impurities such as quicklime and magnesium oxide in the steel slag react with water at high temperature to eliminate the free CaO and free MgO in the steel slag. After the hot stewed steel slag is crushed, screened, and magnetically separated, the metal iron particles and iron concentrate are extracted. The remaining steel slag tailings have good stability and certain activity, and can be used in building materials. However, this method requires a lot of water, and the waste heat in the molten steel slag is not well recovered, or a special waste heat recovery device needs to be added, which increases the production cost.

[0004] Iron tailings are solid wastes left after roughing or concentrating in the process of iron ore mining. At present, the total amount of iron tailings in my country exceeds 7 billion tons, and the comprehensive utilization rate is only 11%. Red mud is a strong alkaline solid waste produced when Al2O3 is extracted from bauxite in the alumina industry. my country produces about 100 million tons of red mud every year, with a cumulative stockpile of about 500 million tons, and the comprehensive utilization rate is only 4%. Iron tailings and red mud are two typical high-water and iron-containing solid wastes that are difficult to treat. The main reasons are as follows:

[0005] The iron tailings are formed through wet grinding, wet magnetic separation, flotation, and concentration to form iron tailings slurry with a concentration of 40% to 60%, which is then transported to the tailings pond through pipelines. Red mud is also transported to the tailings pond through pipelines in the form of red mud slurry with a concentration of 25% to 50%. After the slurry is transported to the tailings pond, it takes a lot of time to settle. The slurry has a low water return rate and slow speed, which also leads to great safety risks in the tailings pond and the environmental risk of polluting groundwater.

[0006] Iron tailings and red mud contain SiO2, Al2O3, CaO and other components, and have certain volcanic ash activity. They can be used as cement admixtures, concrete admixtures, and can also be used to prepare solid waste-based cementitious materials. However, the activity of iron tailings and red mud is relatively low, and high-temperature heating, mechanical grinding and other methods are required to stimulate their activity. However, these methods have high energy consumption, high cost, and high carbon emissions, which restricts the application of tailings and red mud in building materials. In addition, in order to reduce transportation costs, iron tailings and red mud need to be dried before use, which also consumes a lot of energy.

[0007] On the other hand, iron tailings and red mud contain a large amount of weakly magnetic iron oxide. The TFe content in iron tailings is about 25%, and the TFe content in red mud is between 40% and 50%. Some methods attempt to extract the iron component secondary through the method of magnetization reduction roasting. The main steps are: high-temperature roasting of iron tailings and red mud in a reducing atmosphere of H2 and CO to reduce the weakly magnetic Fe2O3 to strongly magnetic Fe3O4, and then magnetically separate the iron concentrate through a weak magnetic separation process. The remaining tailings are used as building materials. However, this method requires high-temperature roasting of 700℃-1000℃ and consumes a lot of energy, which restricts the promotion and application of this method. Summary of the invention

[0008] In view of the deficiencies in the prior art, the object of the present invention is to provide a method for hot stewing of steel slag to extract iron and convert it into building materials by using waste heat to reduce high-water and iron-containing solid waste.

[0009] In order to achieve the above object, the present invention is implemented through the following technical solutions:

[0010] A method for recovering high-water- and iron-containing solid waste by hot stewing of steel slag and converting it into building materials by waste heat includes the following steps:

[0011] S1: mixing iron tailings slurry or / and red mud slurry with carbon powder in a certain proportion to obtain a mixed slurry;

[0012] S2: pouring the molten slag into the slag stewing pool;

[0013] S3: spraying the mixed slurry on the surface of the molten slag;

[0014] S4: After the water in the mixed slurry is evaporated, the steel slag is crushed and turned over, so that the dried and reduced iron tailings and / or red mud and the remaining carbon powder are mixed into the steel slag to form a steel slag mixture;

[0015] S5: Repeat S2 to S4 until the steel slag mixture reaches the rated capacity of the slag tank, and then cover the slag tank;

[0016] S6: injecting water into the slag stewing pool to stew the slag;

[0017] S7: crushing the slag mixture after smelting to extract metallic iron particles;

[0018] S8: After ball milling the remaining material, extracting iron concentrate;

[0019] S9: The remaining tailings are used as raw materials for building materials.

[0020] In some embodiments, the moisture content in the iron tailings slurry is 10%-60%, where % is mass percentage;

[0021] The water content in the red mud slurry is 20%-75%, where % is the mass percentage.

[0022] Preferably, the moisture content in the iron tailings slurry is 40%-60%, where % is mass percentage;

[0023] The water content in the red mud slurry is 40%-60%, where % is the mass percentage.

[0024] Preferably, the mass ratio of solids in the iron tailings slurry and / or red mud slurry to carbon powder is 100:1-5.

[0025] In some embodiments, the mixed slurry accounts for 20%-40% of the mass of the molten steel slag. Carbon powder and water generate reducing gases such as H2 and CO in the high temperature environment provided by the molten steel slag. The reducing gases reduce the weakly magnetic hematite in the iron tailings and / or red mud into strongly magnetic magnetite in the high temperature environment, and then the iron concentrate can be magnetically separated by a weak magnetic separation process, so that the iron component in the iron tailings or red mud can be effectively recovered.

[0026] In some embodiments, the simmering time is 4-8 hours.

[0027] Preferably, the water injection method is to spray water on the top of the slag stewing pool or to inject water from the bottom.

[0028] Preferably, the particle size of the pulverized steel slag after slag stewing is less than 5 mm after crushing.

[0029] In some embodiments, an iron remover is used to extract the metallic iron particles. The metallic iron particles refer to small iron blocks or particles left over from steelmaking, and the TFe grade of the metallic iron particles is above 90%. The remaining material after the extraction of the metallic iron particles contains a large amount of non-magnetic gangue (non-metallic minerals that are useless for steelmaking), which has weak magnetism and is not conducive to ironmaking efficiency. Further grinding is required to separate the strongly magnetic Fe3O4 from the non-magnetic gangue, and then the strongly magnetic Fe3O4 is extracted by magnetic separation.

[0030] In some embodiments, the particle size of the remaining material after wet ball milling is less than 0.075 mm.

[0031] In some embodiments, a weak magnetic separation device is used to extract the iron ore concentrate, and the TFe grade of the iron ore concentrate is above 40%.

[0032] In some embodiments, the remaining tailings are used as raw materials for cement mixtures, concrete admixtures or solid waste-based cementitious materials.

[0033] The beneficial effects achieved by one or more embodiments of the present invention are as follows:

[0034] The waste heat of molten steel slag is used to achieve the drying, reduction magnetization roasting and thermal activation of iron tailings or red mud (after the iron tailings or red mud are heated at 700℃~800℃, the clay minerals in the iron tailings or red mud are completely decomposed into active SiO2 and Al2O3, and their activity as building materials will be improved), saving heat energy consumption and effectively recovering the iron components in the iron tailings or red mud.

[0035] The water in the iron tailings slurry or red mud slurry is used to cool the molten steel slag, realizing the secondary utilization of the slurry water. The ball milling of the steel slag mixture realizes the mechanical activation of the iron tailings or red mud. - The red mud can supplement the aluminum component of the steel slag mixture tailings and provide an alkaline environment. The iron tailings containing a large amount of SiO2 can supplement the silicon component in the steel slag mixture tailings and adjust the ratio of aluminum, calcium and silicon in the steel slag mixture tailings, so that the steel slag mixture tailings have higher activity and can be better used as building materials.

[0036] The present invention realizes the coordinated disposal of multi-source solid wastes and the secondary utilization of molten steel slag waste heat and slurry wastewater, and has significant economic and environmental benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] The accompanying drawings in the specification, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0038] Figure 1 The process flow chart of an embodiment of the present invention. DETAILED DESCRIPTION

[0039] It should be noted that the following detailed descriptions are illustrative and intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used in the present invention have the same meanings as those commonly understood by those skilled in the art to which the present invention belongs.

[0040] The present invention will be further described below in conjunction with the embodiments.

[0041] Example 1

[0042] The method for hot-stewing and iron extraction of steel slag and building materials using waste heat to reduce high-water-content iron-containing solid waste includes the following steps:

[0043] S1: 0.12 tons of carbon powder and 9 tons of iron tailings slurry are mixed evenly to form a mixed slurry. The concentration of the iron tailings slurry is 45%. The main chemical components of the iron tailings are shown in Table 1, and the main components of the carbon powder are shown in Table 2, wherein the % in the following tables are all mass percentages.

[0044] Table 1 Main chemical components of iron ore tailings (%)

[0045]

[0046] Table 2 Main components of carbon powder (%)

[0047]

[0048] S2: Pour 30 tons of molten slag discharged from the converter into the slag stewing pool. Its main chemical composition is shown in Table 3, where % is the mass percentage.

[0049] Table 3 Main chemical components of molten steel slag (%)

[0050]

[0051] S3: 9.12 tons of mixed slurry are sprayed on the surface of molten steel slag. Carbon powder and water generate reducing gases such as H2 and CO in the high temperature environment provided by the molten steel slag. The reducing gases reduce the weakly magnetic hematite in the iron tailings into strongly magnetic magnetite in the high temperature environment.

[0052] S4: After the water in the mixed slurry evaporates, the steel slag is crushed and turned over by an excavator, and the dried and reduced iron tailings are mixed into the steel slag to form a steel slag mixture.

[0053] S5: Repeat the above steps three times to make the steel slag mixture in the slag tank reach the rated capacity, and then cover the slag tank cover to seal it.

[0054] S6: Water is injected into the slag stewing pool through the water pipe at the bottom of the slag stewing pool to make the water cover the steel slag mixture. After soaking for 2 hours, the bottom water valve is opened to drain the water, so that the steel slag mixture is hot stewed in saturated steam for 6 hours.

[0055] S7: After slag stewing, the steel slag mixture in the stewing pool was dug out, and the steel slag mixture was crushed to less than 5mm by a jaw crusher and a rod mill. 9.87 tons of metal iron particles were extracted from the steel slag mixture by an iron remover. The yield of metal iron particles was 9.66%, and the TFe grade was 93.27%.

[0056] S8: The remaining steel slag mixture after removing the metallic iron particles was wet ball-milled to less than 0.075 mm, and magnetically separated by a semi-countercurrent electromagnetic drum-type weak magnetic separator with a magnetic field strength of 87.56 kA / m to extract 32.85 tons of iron ore concentrate. The yield of iron ore concentrate was 32.16%, and the TFe grade was 44.62%.

[0057] S9: After drying the tailings after iron extraction from the steel slag mixture, the remaining tailings mass was 59.43 tons, the yield was 58.18%, and the TFe grade was 13.57%. The activity of the tailings was tested in accordance with the Chinese standard GB / T 12957-2005, and it was found that the 28-day activity index was as high as 73.6%, which met the requirements of the 28-day activity index of Class II steel slag in the Chinese standard GB / T 51003-2014 (≥65%).

[0058] Among them, in S9, solid waste-based cementitious materials were prepared with a mass ratio of tailings: blast furnace slag: P·O42.5 cement: desulfurized gypsum = 30:40:25:5. The mortar specimens were prepared, cured and tested for 28-day compressive strength in accordance with the Chinese standard GB / T 17671-2021. It was found that the 28-day compressive strength reached 38.9 MPa.

[0059] Example 2

[0060] The method for hot-stewing and iron extraction of steel slag and building materials using waste heat to reduce high-water-content iron-containing solid waste includes the following steps:

[0061] S1: 0.11 tons of carbon powder and 7.5 tons of red mud slurry were mixed evenly to form a mixed slurry. The concentration of the red mud slurry was 50%. The main chemical components of the red mud are shown in Table 4, and the main components of the carbon powder are shown in Table 2.

[0062] Table 4 Main chemical components of red mud (%)

[0063]

[0064] S2: Pour 30 tons of molten slag discharged from the converter into the slag stewing pool. Its main chemical composition is shown in Table 3.

[0065] S3: 7.61 tons of mixed slurry are sprayed on the surface of molten steel slag. Carbon powder and water generate reducing gases such as H2 and CO in the high temperature environment provided by the molten steel slag. The reducing gases reduce the weakly magnetic hematite in the red mud into strongly magnetic magnetite in the high temperature environment.

[0066] S4: After the water in the mixed slurry evaporates, the steel slag is crushed and turned over by an excavator, and the dried and reduced red mud is mixed into the steel slag to form a steel slag mixture.

[0067] S5: Repeat the above steps three times to make the steel slag mixture in the slag tank reach the rated capacity, and then cover the slag tank cover to seal it.

[0068] S6: Water is injected into the slag stewing pool through the water pipe at the bottom of the slag stewing pool to make the water cover the steel slag mixture. After soaking for 2 hours, the bottom water valve is opened to drain the water, so that the steel slag mixture is hot stewed in saturated steam for 6 hours.

[0069] S7: After slag stewing, the steel slag mixture in the stewing pool was dug out, and the steel slag mixture was crushed to less than 5mm by a jaw crusher and a rod mill. 9.91 tons of metal iron particles were extracted from the steel slag mixture by an iron remover. The yield of metal iron particles was 9.79%, and the TFe grade was 92.84%.

[0070] S8: The remaining steel slag mixture after removing the metallic iron particles was wet ball-milled to less than 0.075 mm, and magnetically separated by a semi-countercurrent electromagnetic drum-type weak magnetic separator with a magnetic field strength of 87.56 kA / m to extract 32.97 tons of iron ore concentrate. The yield of iron ore concentrate was 32.56%, and the TFe grade was 46.19%.

[0071] S9: After drying the tailings after iron extraction from the steel slag mixture, the remaining tailings mass was 58.37 tons, the yield was 57.65%, and the TFe grade was 13.36%. The activity of the tailings was tested in accordance with the Chinese standard GB / T 12957-2005, and it was found that the 28-day activity index was as high as 83.4%, which met the requirements of the 28-day activity index (≥80%) for Class I steel slag in the Chinese standard GB / T 51003-2014.

[0072] Among them, in S9, solid waste-based cementitious materials were prepared with a mass ratio of tailings: blast furnace slag: P·O42.5 cement: desulfurized gypsum = 30:40:25:5. The mortar specimens were prepared, cured and tested for 28-day compressive strength in accordance with the Chinese standard GB / T 17671-2021, and the strength was found to reach 44.6MPa.

[0073] Comparative Example 1

[0074] A method for hot stewing of steel slag, comprising the following steps:

[0075] S1: Pour 30 tons of molten slag discharged from the converter into the slag pool. Its main chemical composition is shown in Table 3.

[0076] S2: Pour water on the surface of the molten slag to cool it down. When the water on the surface of the slag evaporates completely, use an excavator to crush and turn the slag over.

[0077] S3: Repeat the above steps three times to make the slag in the slag tank reach 90 tons, and cover the hot stewing device with a lid to seal it.

[0078] S4: Water is injected into the slag stewing pool through the water pipe at the bottom of the slag stewing pool to cover the steel slag. After soaking for 2 hours, the bottom water valve is opened to drain the water, so that the steel slag mixture is hot stewed in saturated steam for 6 hours.

[0079] S5: After slag stewing, the pulverized steel slag in the slag stewing pool was dug out, and the pulverized steel slag was crushed to less than 5mm by a jaw crusher and a rod mill. The iron remover was used to extract 9.77 tons of metal iron particles from the pulverized steel slag. The yield of metal iron particles was 10.86%, and the TFe grade was 94.26%.

[0080] S6: The remaining slag after removing the metallic iron was wet ball-milled to less than 0.075 mm, and magnetically separated by a semi-countercurrent electromagnetic drum-type weak magnetic separator with a magnetic field strength of 87.56 kA / m to extract 30.35 tons of iron ore concentrate. The yield of iron ore concentrate was 33.72%, and the TFe grade was 45.83%.

[0081] S7: After drying the tailings after iron extraction from steel slag, the remaining tailings mass was 49.88 tons, the yield was 55.42%, and the TFe grade was 13.09%. The activity of the dried tailings was tested in accordance with the Chinese standard GB / T 12957-2005, and it was found that the 28-day activity index was as high as 76.7%, which met the requirements of the 28-day activity index (≥65%) for Class II steel slag in the Chinese standard GB / T 51003-2014.

[0082] Among them, in S7, solid waste-based cementitious materials were prepared with a mass ratio of tailings: blast furnace slag: P·O42.5 cement: desulfurized gypsum = 30:40:25:5. The mortar specimens were prepared, cured and tested for 28-day compressive strength in accordance with the Chinese standard GB / T 17671-2021, and the strength was found to reach 40.2MPa.

[0083] Comparative Example 2

[0084] A method for converting iron tailings into building materials:

[0085] The iron tailings were dried and sieved to less than 0.075 mm. The activity of the treated iron tailings was tested in accordance with the Chinese standard GB / T 12957-2005, and the 28-day activity index was found to be 58.4%. The solid waste-based cementitious material was prepared with a mass ratio of treated iron tailings: blast furnace slag: P·O42.5 cement: desulfurized gypsum = 30:40:25:5. The mortar specimens were prepared, cured and tested for 28-day compressive strength in accordance with the Chinese standard GB / T 17671-2021, and the strength reached 25.6MPa.

[0086] Comparative Example 3

[0087] A method for converting red mud into building materials:

[0088] The red mud was dried and sieved to less than 0.075 mm. The activity of the treated red mud was tested according to the Chinese standard GB / T 12957-2005, and the 28-day activity index was 60.2%. The solid waste-based cementitious material was prepared with a mass ratio of treated red mud: blast furnace slag: P·O42.5 cement: desulfurized gypsum = 30:40:25:5. The mortar specimens were prepared, cured and tested for 28-day compressive strength according to the Chinese standard GB / T 17671-2021, and the strength reached 28.4 MPa.

[0089] The iron component recovery results of Example 1, Example 2 and Comparative Example 1 are compared in Table 5. The solid waste activity and 28-day compressive strength test results of solid waste-based cementitious materials of Example 1, Example 2, Comparative Example 1, Comparative Example 2 and Comparative Example 3 are compared in Table 6.

[0090] Table 5 Comparison of iron component recovery test results

[0091]

[0092] Table 6 Comparison of tailings activity and 28-day compressive strength test results of solid waste-based cementitious materials

[0093]

[0094] According to Table 5, by comparing Example 1 and Example 2 with Comparative Example 1, it can be obviously obtained that when the quality of molten slag is the same, compared with the traditional slag hot stewing treatment method, the TFe grade of the metallic iron particles extracted by the waste heat reduction method of hot stewing of slag for iron extraction and building material production of high-water-containing iron-containing solid waste and the like of the present invention is slightly decreased, and the output is slightly increased. This is due to the reducing effect of carbon powder on the molten slag.

[0095] According to Table 5, by comparing Example 1 and Example 2 with Comparative Example 1, it can be obviously obtained that when the quality of molten slag is the same, compared with the traditional slag hot stewing treatment method, the TFe grade of the iron ore concentrate extracted by the present invention is very small, and the output is significantly increased. The output of iron ore concentrate in Example 1 increases by 2.5 tons, and the output of iron ore concentrate in Example 2 increases by 2.62 tons.

[0096] According to Table 5, by comparing Example 1 and Example 2 with Comparative Example 1, it can be obviously obtained that when the quality of molten slag is the same, compared with the traditional slag hot stewing treatment method, the TFe grade of the tailings produced by the waste heat reduction of high-water-containing and iron-containing solid waste and the building material method of the present invention is very small, and the output is significantly increased. The tailings output of Example 1 increases by 95,500 tons, and the tailings output of Example 2 increases by 84,900 tons.

[0097] According to Table 6, by comparing Example 1 and Example 2 with Comparative Example 1, Comparative Example 2 and Comparative Example 3, it can be obviously obtained that when the quality of molten steel slag is the same, compared with the traditional steel slag hot stewing treatment method, the activity of the tailings produced by dumping iron tailings slurry on the surface of molten steel slag in the present invention is reduced by 3.1%, but can still meet the requirements of the 28-day activity index (≥65%) for Class II steel slag in the national standard GB / T 51003-2014; the activity of the tailings produced by dumping red mud slurry on the surface of molten steel slag is significantly increased, increased by 6.7%, which can meet the requirements of the 28-day activity index (≥80%) for Class I steel slag in the national standard GB / T 51003-2014.

[0098] According to Table 6, it can be clearly obtained that, by comparing Example 1 with Comparative Example 2, compared with the iron tailings that have only been dried and screened, the activity of the tailings produced by dumping the iron tailings slurry on the surface of the molten steel slag in the present invention is significantly increased, by 15.2%. This is because the waste heat of the molten steel slag in the present invention has a thermal activation effect on the iron tailings, so that the clay minerals in the iron tailings are decomposed into active SiO2 and Al2O3, and the dissolution of active silicon, aluminum and other components is promoted; and the ball milling of the remaining material in the present invention has a mechanical activation effect on the iron tailings, destroying the passivated mucous film on the surface of the iron tailings particles, and also promoting the dissolution of active silicon, aluminum and other components, and the ball milling increases the specific surface area of ​​the iron tailings particles, and increases the contact area of ​​the iron tailings particles participating in the hydration reaction.

[0099] According to Table 6, it can be clearly obtained that by comparing Example 2 with Comparative Example 3, compared with the red mud that has only been dried and screened, the activity of the tailings produced by dumping the red mud slurry on the surface of the molten steel slag in the present invention is significantly increased by 23.2%. This is because the waste heat of the molten steel slag in the present invention has a thermal activation effect on the red mud, so that the clay minerals in the red mud are decomposed into active SiO2 and Al2O3, and the dissolution of active silicon, aluminum and other components is promoted; and the ball milling of the remaining material in the present invention has a role in mechanically activating the red mud.

[0100] According to Table 6, by comparing Example 1 and Example 2 with Comparative Example 1, it can be clearly obtained that when the mass of molten steel slag is the same, compared with the traditional steel slag hot stewing method, the strength of the solid waste-based cementitious material prepared by the tailings produced by dumping iron tailings slurry on the surface of molten steel slag in the present invention is slightly reduced by 3.2%; the strength of the solid waste-based cementitious material prepared by the tailings produced by dumping red mud slurry on the surface of molten steel slag is significantly increased by 10.9%, which can meet the strength requirements of 45.2# cement. This is because the red mud supplements the Al2O3 in the solid waste-based cementitious material, and the OH in the red mud -An alkaline environment is provided, and the solid waste-based gelling material in Example 2 undergoes an alkali-excited reaction to generate more hydrated aluminosilicate gel and hydrated aluminate gel, which improves the strength of the solid waste-based gelling material.

[0101] According to Table 6, it can be obviously obtained that by comparing Example 1 with Comparative Example 2, compared with the iron tailings that have only been dried and screened, the strength of the solid waste-based cementitious material prepared from the tailings produced by dumping iron tailings slurry on the surface of molten steel slag in the present invention is significantly increased. This is because the tailings produced by dumping iron tailings slurry on the surface of molten steel slag in the present invention have higher activity after thermal activation and mechanical activation, and react with blast furnace slag, P·O42.5 cement and desulfurized gypsum to generate more cementitious substances.

[0102] According to Table 6, it can be obviously obtained that by comparing Example 2 with Comparative Example 3, compared with the red mud that has only been dried and screened, the strength of the solid waste-based cementitious material prepared from the tailings produced by dumping red mud slurry on the surface of molten steel slag of the present invention is significantly increased. This is because the tailings produced by dumping red mud slurry on the surface of molten steel slag of the present invention have higher activity after thermal activation and mechanical activation, and react with blast furnace slag, P·O42.5 cement and desulfurized gypsum to generate more cementitious substances.

[0103] In summary, the present invention utilizes the waste heat of molten steel slag to achieve drying, reduction magnetization roasting and thermal activation of iron tailings or red mud, increases the yield of metallic iron particles and iron concentrate, and effectively recovers the iron components in iron tailings or red mud. - The red mud supplements the aluminum component of the steel slag mixture tailings, provides an alkaline excitation environment, and makes the steel slag mixture tailings more active; the activity of the iron tailings and the steel slag mixture tailings is slightly reduced, but the impact is not significant, and the tailings can be used as building materials; compared with the iron tailings / red mud that have only been dried and screened, the tailings produced by dumping the iron tailings / red mud slurry on the surface of the molten steel slag have undergone thermal activation and mechanical activation, and have higher activity. The strength of the solid waste-based cementitious material prepared from the steel slag mixture tailings is higher. The present invention realizes the coordinated disposal of multi-source solid wastes, realizes the secondary utilization of the waste heat of the molten steel slag and the slurry wastewater, and has significant economic and environmental benefits.

[0104] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for hot-stewing and building material extraction of steel slag from high-water and high-iron-containing solid waste using waste heat, characterized in that: The steps include: S1: mixing iron tailings slurry or / and red mud slurry with carbon powder in a certain proportion to obtain a mixed slurry; S2: pouring the molten slag into the slag stewing pool; S3: spraying the mixed slurry on the surface of the molten slag; S4: After the water in the mixed slurry is evaporated, the steel slag is crushed and turned over, so that the dried and reduced iron tailings and / or red mud and the remaining carbon powder are mixed into the steel slag to form a steel slag mixture; S5: Repeat S2 to S4 until the steel slag mixture reaches the rated capacity of the slag tank, and then cover the slag tank; S6: injecting water into the slag stewing pool to stew the slag; S7: crushing the slag mixture after smelting to extract metallic iron particles; S8: After ball milling the remaining material, extracting iron concentrate; S9: The remaining tailings are used as raw materials for building materials; The moisture content of the iron tailings slurry is 40%-60%, and the moisture content of the red mud slurry is 40%-60%, where % is mass percentage; The mixed slurry accounts for 20%-40% of the mass of the molten steel slag, and the mass ratio of the iron tailings or / and red mud to the carbon powder in the mixed slurry is 100:1-5; Carbon powder and water generate reducing gas in a high temperature environment provided by molten steel slag, and the reducing gas reduces weakly magnetic hematite in the iron tailings and / or red mud into strongly magnetic magnetite in the high temperature environment.

2. The method for recovering high-water- and iron-containing solid waste by hot simmering of steel slag and converting it into building materials by waste heat reduction according to claim 1, characterized in that: The slag stewing time is 4-8 hours; the particle size of the powdered steel slag after stewing is less than 5mm after crushing.

3. The method for recovering high-water- and iron-containing solid waste by hot simmering of steel slag and converting it into building materials by waste heat reduction according to claim 1, characterized in that: Use an iron remover to extract the metallic iron particles.

4. The method for recovering high-water- and iron-containing solid waste by hot simmering of steel slag and converting it into building materials by waste heat reduction according to claim 1, characterized in that: The particle size of the remaining material after wet ball milling is less than 0.075 mm.

5. The method for recovering high-water- and iron-containing solid waste by hot simmering of steel slag and converting it into building materials according to claim 1, characterized in that: A weak magnetic separation device is used to extract the iron concentrate.

6. The method for recovering high-water- and iron-containing solid waste by hot simmering of steel slag and converting it into building materials according to claim 1, characterized in that: The remaining tailings are used as raw materials for cement mixtures, concrete admixtures or solid waste-based cementitious materials.

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