A production method for extracting manganese oxide from low-alkalinity slag and modifying it into mineral wool raw material

Abstract

The application discloses a production method for extracting manganese oxide from low-alkalinity casting slag and modifying the low-alkalinity casting slag into mineral wool raw materials, and belongs to the technical field of metallurgical solid waste resource utilization. According to the temperature, composition and quality of the low-alkalinity casting slag, the mass of carbon materials and modifying agents is calculated; then, the corresponding mass of carbon materials and modifying agents is added into a slag basin, and the stirring tank is stirred for 2-4 minutes and then cooled; the cooled low-alkalinity casting slag is broken and separated by gravity separation to obtain MnO and mineral wool raw materials. Through control of the slag reducibility, the MnO in the low-alkalinity casting slag is efficiently recovered, and the slag is modified into the mineral wool raw materials, so that the consumption of natural basalt in the production of the mineral wool is saved, and great economic value is brought to a steel enterprise.

Description

Technical Field

[0001] The present invention belongs to the technical field of metallurgical solid waste resource utilization, and more specifically relates to a production method for extracting manganese oxide from low-alkalinity casting slag and reforming it into mineral wool raw material. Background Art

[0002] Casting slag is primarily a mixture of excess steel and slag left at the bottom of the ladle during the continuous casting process to ensure ingot quality. Most casting slag contains high levels of iron and alloys, making it much more valuable for recycling than ordinary steel slag. However, it tends to pulverize during cooling and generate dust during storage, creating more serious environmental problems than steel slag.

[0003] There are many types of casting slag with different compositions. Among them, low-alkalinity casting slag accounts for the largest proportion and the highest recycling value. It is produced by the ordinary carbon steel smelting process and accounts for about 40% of the total casting slag. Since it is directly alloyed with silicon-manganese alloy without being reduced in a refining furnace, the MnO content in the slag can reach more than 20%, which has extremely high recycling value. At the same time, the alkalinity is about 0.5, and a slight modification can meet the composition requirements of mineral wool raw materials.

[0004] Mineral wool has excellent properties such as low density, low thermal conductivity, and high temperature resistance. It is currently widely used in the construction field, industrial production, and residents' lives. Mineral wool uses silicates as raw materials and is melted and sprayed under high temperature conditions to make fiber wool. The raw material for producing mineral wool is mainly basalt. After compounding metallurgical solid waste such as fly ash, blast furnace slag, and casting residue, the chemical composition and content are similar to those contained in basalt minerals. They can replace basalt to produce fibers, reducing the use of natural ores in the mineral wool production process. The composition of mineral wool raw materials prepared from metallurgical solid waste can be flexibly changed according to process requirements. The composition is stable and controllable, making the product fiber strength, chemical stability, and slag ball content superior to natural basalt mineral wool products, thereby improving the high added value utilization of metallurgical solid waste.

[0005] The existing utilization of low-basicity foundry slag has the following problems: 1) Low-basicity foundry slag is not given enough attention and is often mixed with steel slag; 2) The MnO contained in low-basicity foundry slag is oxidized to MnO2 by air during high-temperature cooling, greatly reducing its recycling value; 3) There is a lack of scientific guidance when converting low-basicity foundry slag into mineral wool raw material, resulting in poor product quality.

[0006] Patent CN103145342A discloses a hot slag mineral wool for steel production and its preparation method. The raw material for the hot slag mineral wool is composed of the following components, calculated by mass percentage: 70-90% liquid blast furnace slag and 10-30% tempering material. The preparation method involves introducing the hot blast furnace slag directly into the primary melting zone of the slag furnace via a slag trough. The tempering material and the hot blast furnace slag are then simultaneously introduced into the primary melting zone of the slag furnace. The melt temperature in the primary melting zone is maintained at 1400-1500°C for 4-6 hours before entering the main melting zone, where the melt temperature is maintained at 1420-1450°C for 6-9 hours. The wool then enters the discharge zone and flows onto the rollers of a centrifuge to form the raw wool.

[0007] Patent CN108642224A discloses a method for modifying converter slag using blast furnace slag and molten iron, which comprises the following steps: 1) pouring high-temperature liquid blast furnace slag containing molten iron into an electric furnace; 2) adding the total carbon mass relationship formula MC>K×(α×M1+β×M2+λ×M3+ε×M4) in the molten iron based on the carbon and silicon content of the reducing agent, the oxide content of the converter slag, and the oxide content of the final slag; 3) adding high-temperature liquid converter slag to the interior of the electric furnace while carrying out step 1), with the mass ratio of high-temperature liquid converter slag to high-temperature liquid blast furnace slag being 1:(3-6); 4) providing heat by heating with graphite electrodes in the electric furnace, and recovering high-temperature flue gas at the same time; 5) heating for 10-30 minutes, and when the FeO content drops below a certain range, the final slag and molten iron flow out from the slag outlet and iron outlet of the electric furnace, respectively.

[0008] The above methods are all aimed at the modification of blast furnace slag and converter slag, and are not suitable for low-alkalinity casting slag with very different compositions. How to modify low-alkalinity casting slag, effectively extract high-value-added MnO and produce mineral wool is still a problem that needs to be solved. Summary of the Invention

[0009] 1. Problem to be solved

[0010] To address the problem that existing reforming methods are not suitable for low-alkalinity foundry slag, resulting in the inability to effectively extract high-value-added products, the present invention provides a production method for extracting manganese oxide from low-alkalinity foundry slag and reforming it into mineral wool raw material. The method can efficiently recover MnO from the low-alkalinity foundry slag and reform the slag into high-quality mineral wool raw material.

[0011] 2. Technical solution

[0012] In order to solve the above problems, the technical solutions adopted by the present invention are as follows:

[0013] The present invention provides a production method for extracting manganese oxide from low-alkalinity casting slag and reforming it into mineral wool raw material, comprising the following steps:

[0014] S1: Calculate the mass of added carbon material and modifier according to the temperature, composition and mass of low basicity casting residue;

[0015] S2: Add carbon material and modifier to the slag basin, stir in a stirring kettle for 2-4 minutes and wait for cooling;

[0016] S3: Crushing and cooling the low-alkalinity casting slag, and gravity separation to obtain MnO and mineral wool raw materials.

[0017] The low-basicity casting slag comprises the following components by mass fraction: CaO: 18%-24%, SiO2: 32%-46%, Al2O3 12%-20%, MgO: 4%-8%, MnO: 18%-30%, S: 0.02%-0.1%, P2O5: 0.04%-0.12%, and the basicity (CaO+MgO) / (SiO2+Al2O3) is 0.4-0.6.

[0018] This application is aimed at modifying low-alkalinity casting slag. Compared with blast furnace slag and converter slag, low-alkalinity casting slag contains more MnO, which is conducive to extracting more high-value-added MnO. At the same time, due to its lower alkalinity, there is no need to add excessive modifiers during the modification process to increase the proportion of CaO and MgO in the casting slag and reduce the acidity. By comprehensively considering the composition and alkalinity of the casting slag, efficient extraction of MnO and mineral wool is achieved while consuming less modifiers.

[0019] The purpose of adding carbon material in step S1 is to control the reducibility of the casting slag, prevent MnO from being oxidized to MnO2 by air at high temperature, and reduce the yield of MnO. The calculation formula for the amount of carbon material added is as follows:

[0020]

[0021] Where: M 碳 is the mass of carbon material added, r is the radius of the slag basin liquid surface, k is the carbon combustion coefficient, M 渣 is the mass of the casting slag, η is the attenuation coefficient, T is the end temperature, T0 is the initial temperature of the casting slag, ω 碳 is the mass fraction of carbon in carbon materials.

[0022] Furthermore, the endpoint temperature is a parameter used to calculate the temperature at which carbon material is added. Depending on actual environmental conditions, the actual endpoint temperature, when adjusted to 375-425°C, can ensure that MnO is not oxidized by air. In actual calculations, to achieve the most economical and efficient addition mode, the present invention controls the endpoint temperature T to 400°C. Above 400°C, MnO is oxidized to MnO2 by oxygen in the air, reducing the MnO yield after gravity separation. Setting the endpoint temperature too low wastes carbon material and increases process costs.

[0023] Furthermore, the present invention does not limit the type of carbon material added, but only assesses the absolute quality of the carbon added. The preferred carbon material is renewable biochar such as carbonized rice husks and carbonized straw.

[0024] Furthermore, the addition of carbon material in the present invention has a significant beneficial effect on the quality of mineral wool raw materials. When the carbon material burns, the CO2 and CO gases generated have a stirring effect on the casting slag and the modifier. When the carbon material burns, the excess heat generated reduces the cooling rate of the casting slag. The combined action of the two promotes the reaction between the casting slag and the modifier to reach a balance, resulting in a uniform composition of the mineral wool raw material and greatly reducing the slag ball rate of the mineral wool product.

[0025] The purpose of adding the modifier in step S1 is to control the chemical composition of the casting slag to meet the acidity and hydrogen ion index requirements of high-quality mineral wool raw materials. Acidity primarily affects the operating temperature of the mineral wool product and the length and diameter of the mineral wool fibers. Literature recommends a range of 1.3-1.7, and this method controls it to 1.5. The hydrogen ion index affects the water resistance of the mineral wool fibers. Literature recommends a range of less than 5, and this method controls it to 4.

[0026] The acidity of the low-alkalinity casting slag treated by the present invention is generally around 2.0. It is necessary to increase the specific gravity of CaO and MgO and reduce the acidity. Therefore, the modifiers are limestone and dolomite. The effective component of limestone is CaCO3, and the effective component of dolomite is CaMg(CO3)2. Limestone and dolomite are carbonates, which can be decomposed into CaO and MgO using the waste heat of the casting slag. The CO2 generated by the decomposition is retained in the casting slag to form a loose porous structure, reducing the difficulty of subsequent crushing.

[0027] The amount of modifier added can be obtained by solving the following equations simultaneously. The specific calculation formula is as follows:

[0028]

[0029]

[0030] Where, is the mass fraction of SiO2 after modification, is the mass fraction of Al2O3 after modification, W CaO is the mass fraction of CaO after modification, W MgO is the mass fraction of MgO after modification.

[0031] Furthermore, the amount of carbon material added cannot be too large. It is necessary to ensure that the added carbon material is completely burned when the modification is completed. Otherwise, the included carbon material will greatly deteriorate the cotton-forming properties of the mineral wool raw material. Therefore, it is necessary to calculate the maximum amount of carbon material added based on the actual addition of the modifier. In actual production, the quality of the carbon material input must be strictly guaranteed to be less than the maximum value. The formula for calculating the maximum amount of carbon material added is as follows:

[0032]

[0033] Where: is the maximum amount of carbon material added, C i is the specific heat capacity of the modifier (dolomite and limestone in this method, the same below), M i is the mass of modifier added, ΔT is the temperature difference before and after the addition of modifier, ΔH i is the decomposition heat of the modifier, u g is the gas diffusion coefficient, r is the radius of the slag basin, q 碳 is the calorific value of 1kg carbon element, ω 碳 is the mass fraction of carbon in carbon material, and k is the carbon combustion coefficient.

[0034] In step S2, the carbon material and modifier of the corresponding mass calculated in step S1 are directly put into the slag basin and covered on the surface of the casting slag. Then, the slag basin is moved to the stirring position, the stirring kettle is lowered and immersed in the casting slag and stirred for 2-4 minutes, and then the stirring kettle is lifted and the casting slag is allowed to cool.

[0035] Among them, the stirring time is controlled to 2-4 minutes in order to ensure that the casting slag is fully mixed with the carbon material and the modifier. However, if the stirring time is too long, the fluidity of the casting slag will deteriorate when the slag cools, or even completely solidify. When the stirring kettle is lifted, a large amount of casting slag will adhere, making it impossible to lift the stirring kettle.

[0036] Furthermore, the crushing in step S3 includes coarse crushing and grinding, and the particle size of the slag after crushing is required to be less than 50 mesh. Then, MnO and mineral wool raw materials are separated by gravity separation equipment such as jigs, shaking tables, chutes, etc. MnO and mineral wool raw materials are both high value-added industrial raw materials with high economic value. Among them, MnO and mineral wool raw materials can be separated by gravity separation because the density of MO is 5.43g / cm 3 The highest density component in mineral wool is Al2O3, with a density of 3.6g / cm 3 , under the action of centrifugal force, MnO is separated from other components.

[0037] 3. Beneficial effects

[0038] Compared with the prior art, the present invention has the following beneficial effects:

[0039] (1) The present invention provides a production method for extracting manganese oxide from low-alkalinity casting slag and reforming it into mineral wool raw materials. The method utilizes casting slag from the ordinary carbon steel production process, adds carbon materials and modifiers, and converts metallurgical solid waste with low utilization value into high-value-added MnO industrial raw materials and mineral wool raw materials, which has extremely high economic value.

[0040] (2) The production method of extracting manganese oxide from low-alkalinity casting slag and reforming it into mineral wool raw material of the present invention realizes fine control of the recovery process compared with the existing casting slag recovery technology. Carbon materials and modifiers are quantitatively added according to theoretical calculations and empirical formulas, thereby realizing fine and stable control of the casting slag composition, achieving energy conservation and emission reduction, making the best use of resources, and practicing the scientific, systematic and resourceful treatment of metallurgical solid waste.

[0041] (3) The present invention provides a production method for extracting manganese oxide from low-alkalinity casting slag and reforming it into mineral wool raw material. Compared with existing casting slag recovery technology, the present invention overcomes the oxidation problem in the manganese recovery process. Conventional recovery methods can only produce MnO2 of lower value. The present invention achieves effective recovery of MnO by controlling the reducibility of casting slag.

[0042] (4) Compared with the existing method for preparing mineral wool raw materials, the method of the present invention has the advantages of not using natural basalt, saving non-renewable resources, stable and controllable composition, small amount of modifier added, and simple process flow. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] The technical solutions of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. However, it should be understood that these drawings are designed for illustrative purposes only and are not intended to limit the scope of the present invention. Furthermore, unless otherwise specified, these drawings are intended only to conceptually illustrate the structures described herein and are not necessarily drawn to scale.

[0044] Figure 1 This is a comparison chart of the acidity of mineral wool raw materials;

[0045] Figure 2 This is a comparison chart of the hydrogen ion index of mineral wool raw materials;

[0046] Figure 3 It is a process flow chart of the present invention. DETAILED DESCRIPTION

[0047] The following detailed description of exemplary embodiments of the present invention refers to the accompanying drawings, which form a part of the description, and in which exemplary embodiments of the present invention that can be implemented are shown as examples. Although these exemplary embodiments are described in sufficient detail to enable those skilled in the art to implement the present invention, it should be understood that other embodiments can be implemented and various changes can be made to the present invention without departing from the spirit and scope of the present invention. The following more detailed description of the embodiments of the present invention is not intended to limit the scope of the claimed invention, but is merely for illustration and does not limit the description of the features and characteristics of the present invention, so as to propose the best way to perform the present invention and be sufficient to enable those skilled in the art to implement the present invention. Therefore, the scope of the present invention is limited only by the appended claims.

[0048] Example 1

[0049] The casting slag used in Example 1 was a randomly selected casting slag from a heat at the steel mill of Anhui Changjiang Iron and Steel Co., Ltd., with a temperature of 1520°C, a mass of 2680 kg, and a basicity of 0.473. The detailed composition is shown in Table 1-1 below. The carbon material used was carbonized rice husk, purchased from Yutai Chuangjian Insulation Materials Co., Ltd., with an effective carbon content of 66.3%. The modifiers, limestone and dolomite, were provided by Anhui Changjiang Iron and Steel Co., Ltd. The limestone had an effective CaCO3 content of 93.1%, and the dolomite had an effective CaMg(CO3)2 content of 88.3%.

[0050] Table 1-1 Composition of casting slag of Example 1 (wt%)

[0051] CaO <![CDATA[SiO2]]> <![CDATA[Al2O3]]> MgO MnO S <![CDATA[P2O5]]> 20.4 38.8 15.68 5.37 23.19 0.059 0.073

[0052] The composition of the casting slag is obtained by chemical analysis in the steel plant, wherein S and P2O5 have no effect on the calculation of the present invention and are not considered in subsequent calculations.

[0053] The production method of Example 1, which extracts manganese oxide from low-alkalinity casting slag and reforms it into mineral wool raw material, comprises the following steps:

[0054] S1: Calculate the mass of added carbon material and modifier based on the temperature, composition and mass of low basicity casting residue.

[0055] Calculate the amount of carbon material added according to the calculation formula:

[0056]

[0057] Where: M 碳 is the mass of carbon material added, r is the radius of the slag basin liquid surface, k is the carbon combustion coefficient, M 渣 is the mass of the casting slag, η is the attenuation coefficient, T is the end point control temperature, T0 is the initial temperature of the casting slag, ω 碳The mass fraction of carbon in the carbonaceous material. The specific value is shown in Table 1-2.

[0058] Table 1-2 Calculation parameters of carbonaceous material addition amount in Example 1

[0059] r / m <![CDATA[k / (kg / m 2 ·s)]]> <![CDATA[M 渣 / kg]]> η / s -1 ]]> 0.8 0.083 2680 -0.207 T / ℃ [T0 / °C] <![CDATA[ω 碳 / %]]> <![CDATA[M 碳 / kg]]> 400 1520 66.3 186

[0060] In this embodiment, the endpoint temperature T is controlled to be 400℃, and the calculation shows that the mass of added carbonized rice husk is 186kg. The acidity of the mineral wool raw material is controlled to be 1.5, and the hydrogen ion index is 4.

[0061] The modifying agent is limestone and dolomite, the effective component of limestone is CaCO3, the effective component of dolomite is CaMg(CO3)2, and limestone and dolomite are carbonates.

[0062] The addition amount of the modifying agent can be obtained by solving the following equation set, and the specific calculation formula is as follows:

[0063]

[0064]

[0065] In the formula: W is the mass of SiO2 after modification, W is the mass of Al2O3 after modification, CaO W is the mass of CaO after modification, MgO W is the mass of MgO after modification. Among them, the modifying agent does not contain SiO2 and Al2O3, so the mass of SiO2 and Al2O3 before and after modification is the same.

[0066] According to the actual data calculation, the specific steps are as follows:

[0067] 1) W CaO + W MgO = 973.4

[0068] 2) 0.26W CaO + 0.105W MgO = 220.2

[0069] 3) W CaO = 761.4; W MgO = 212

[0070] Therefore, the mass of CaO required to be added is 214.7kg, and the mass of MgO required to be added is 68kg. Since the actual modifying agent added is limestone and dolomite, it is also necessary to calculate inversely according to the effective component. In this embodiment, the simple mathematical calculation steps according to the actual data are given as follows:

[0071]

[0072] Right now

[0073]

[0074] Right now

[0075] Where: W MgO is the mass of MgO to be added, mol 白云石 is the relative molecular mass of the effective component CaMg(CO3)2 in dolomite, mol MgO is the relative molecular mass of MgO, ω 白云石 is the effective CaMg(CO3)2 content of dolomite, W CaO is the mass of CaO to be added, is the mass of CaO in dolomite, mol 石灰石 is the relative molecular mass of the effective component CaCO3 in limestone, mol CaO is the relative molecular mass of CaO, ω 石灰石 It is the effective CaCO3 content of limestone.

[0076] Calculation shows that the mass of dolomite added is 358 kg and the mass of limestone added is 229 kg.

[0077] According to the actual addition of the modifier, the maximum amount of carbon material added is calculated. In actual production, the quality of the carbon material input must be strictly guaranteed to be less than the maximum value. The formula for calculating the maximum amount of carbon material added is as follows:

[0078]

[0079] Where: is the maximum amount of carbon material added, C i is the specific heat capacity of the modifier (dolomite and limestone in this method, the same below), M i is the mass of modifier added, ΔT is the temperature difference before and after the addition of modifier, ΔH i is the decomposition heat of the modifier, u g is the gas diffusion coefficient, r is the radius of the slag basin, q 碳 is the calorific value of 1kg carbon element, ω 碳 is the mass fraction of carbon in carbon material, and k is the carbon combustion coefficient.

[0080] See Table 1-3 for specific values.

[0081] Table 1-3 Calculation parameters for the maximum amount of carbon material added in Example 1

[0082] <![CDATA[C 白云石 / (KJ / (kg·℃))]]> <![CDATA[C 石灰石 / (KJ / (kg·℃))]]> <![CDATA[M 白云石 / kg]]> M 石灰石 / kg]]> 0.806 0.59 358 229 ΔT / ℃ <![CDATA[ΔH 白云石 / (KJ / kg)]]> <![CDATA[ΔH 石灰石 / (KJ / kg)]]> <![CDATA[u g / kg·s -1 ]]> 1495 203.6 178.3 1.43 <![CDATA[q 碳 / (KJ / kg)]]> r / m <![CDATA[ω 碳 / %]]> <![CDATA[k / (kg / m 2 ·s)]]> 29700 0.8 66.3 0.083

[0083] Calculation of the maximum amount of carbon material added It is 235 kg, which is greater than the carbon material addition amount of 186 kg calculated by S1, so the actual carbon material addition amount is 186 kg.

[0084] S2. Add the corresponding mass of carbonized rice husk, dolomite and limestone calculated in S1 directly into the slag basin, covering the surface of the casting slag. Then move the slag basin to the stirring position, lower the stirring kettle into the casting slag and stir for 2-4 minutes. Then raise the stirring kettle and wait for the casting slag to cool.

[0085] S3. Crushing the cooled casting slag involves coarse crushing and grinding. A PE400*600 jaw crusher is used for coarse crushing, and an MQG2700*4500 ball mill is used for grinding. The slag is ground to a particle size of less than 50 mesh. A JT1.5-2S jig is then used to separate the MnO from the mineral wool raw material. The separated MnO yielded 493 kg, a 79.3% yield, and 457 kg of active ingredients. The mineral wool raw material yielded 1919 kg, a 93.2% yield, and 1844 kg of active ingredients. The separated MnO and mineral wool raw material are stored in a warehouse. Both are high-value-added industrial raw materials with high economic value.

[0086] Example 2

[0087] The casting slag used in Example 2 was a randomly selected casting slag from a heat at the steel mill of Anhui Changjiang Iron and Steel Co., Ltd., with a temperature of 1487°C, a mass of 2470 kg, and a basicity of 0.452. The detailed composition is shown in Table 2-1 below. The carbon material used was carbonized straw, purchased from Yutai Chuangjian Insulation Materials Co., Ltd., with an effective carbon content of 71.4%. The modifiers, limestone and dolomite, were provided by Anhui Changjiang Iron and Steel Co., Ltd. The limestone had an effective CaCO3 content of 93.1%, and the dolomite had an effective CaMg(CO3)2 content of 88.3%.

[0088] Table 2-1 Composition of Casting Slag of Example 2 (wt%)

[0089] CaO SiO2 <![CDATA[Al2O3]]> MgO MnO S <![CDATA[P2O5]]> 19.53 38.53 16.82 5.49 22.2 0.047 0.091

[0090] The composition of the casting slag is obtained by chemical analysis in the steel plant, wherein S and P2O5 have no effect on the calculation of the present invention and are not considered in subsequent calculations.

[0091] The production method of Example 2, which is to extract manganese oxide from low-alkalinity casting slag and reform it into mineral wool raw material, comprises the following steps:

[0092] S1: Calculate the mass of added carbon material and modifier based on the temperature, composition and mass of low basicity casting residue.

[0093] Calculate the amount of carbon material added according to the calculation formula:

[0094]

[0095] Where: M 碳 is the mass of carbon material added, r is the radius of the slag basin liquid surface, k is the carbon combustion coefficient, M 渣 is the mass of the casting slag, η is the attenuation coefficient, T is the end point control temperature, T0 is the initial temperature of the casting slag, ω 碳 is the mass fraction of carbon in carbon materials. Specific values ​​are shown in Table 2-2.

[0096] Table 2-2 Calculation parameters of carbon material addition amount in Example 2

[0097] r / m <![CDATA[k / (kg / m 2 ·s)]]> <![CDATA[M 渣 / kg]]> <![CDATA[η / s -1 ]]> 0.8 0.083 2680 -0.207 T / ℃ <![CDATA[T0 / ℃]]> <![CDATA[ω 碳 ]]> <![CDATA[M 碳 / kg]]> 400 1520 71.4 157

[0098] In this embodiment, the end temperature T is controlled to 400° C., and the mass of carbonized rice husk added is calculated to be 157 kg. The acidity of the mineral wool raw material is controlled to be 1.5, and the hydrogen ion index is controlled to be 4.

[0099] The modifiers are limestone and dolomite, the effective component of limestone is CaCO3, the effective component of dolomite is CaMg(CO3)2, and the limestone and dolomite are carbonates.

[0100] The amount of modifier added can be obtained by solving the following equations simultaneously. The specific calculation formula is as follows:

[0101]

[0102]

[0103] Where: The quality of SiO2 after modification, is the quality of Al2O3 after modification, W CaO is the mass of CaO after modification, W MgO is the mass of MgO after modification.

[0104] Calculation shows that the mass of dolomite added is 340 kg and the mass of limestone added is 266 kg.

[0105] Further calculation shows that the maximum amount of carbon material added is 219 kg, which is greater than the 157 kg amount of carbon material added calculated by S1, so the actual amount of carbon material added is 157 kg.

[0106] S2. Add the corresponding mass of carbonized rice husk, dolomite and limestone calculated in S1 directly into the slag basin, covering the surface of the casting slag. Then move the slag basin to the stirring position, lower the stirring kettle into the casting slag and stir for 2-4 minutes. Then raise the stirring kettle and wait for the casting slag to cool.

[0107] S3. Crushing the cooled casting slag involves coarse crushing and grinding. A PE400*600 jaw crusher is used for coarse crushing, and an MQG2700*4500 ball mill is used for grinding. The grinding results in a particle size of less than 50 mesh. A JT1.5-2S jig is then used to separate the MnO from the mineral wool raw material. The separated MnO yielded 455 kg, a 76.5% yield, and 437 kg of active ingredients. The mineral wool raw material yielded 1769 kg, a 84.8% yield, and 1709 kg of active ingredients. The separated MnO and mineral wool raw material are stored in a warehouse. Both are high-value-added industrial raw materials with high economic value.

[0108] Example 3

[0109] The casting slag used in Example 3 was a randomly selected casting slag from a steel mill of Changzhou Zhongtian Iron and Steel Group Co., Ltd., with a temperature of 1547°C, a mass of 3227 kg, and a basicity of 0.511. The detailed composition is shown in Table 3-1 below. The carbon material used was carbonized straw, purchased from Hefei Debo Bioenergy Technology Co., Ltd., with an effective carbon content of 69.2%. The modifiers, limestone and dolomite, were provided by Changzhou Zhongtian Iron and Steel Group Co., Ltd.; the limestone had an effective CaCO3 content of 94.7%, and the dolomite had an effective CaMg(CO3)2 content of 90.7%.

[0110] Table 3-1 Composition of Casting Slag of Example 3 (wt%)

[0111] CaO <![CDATA[SiO2]]> Al2O3 MgO MnO S <![CDATA[P2O5]]> 21.2 40.17 15.41 7.22 21.3 0.32 0.103

[0112] The composition of the casting slag is obtained by chemical analysis in the steel plant, wherein S and P2O5 have no effect on the calculation of the present invention and are not considered in subsequent calculations.

[0113] The production method of Example 3, which is to extract manganese oxide from low-alkalinity casting slag and reform it into mineral wool raw material, comprises the following steps:

[0114] S1: Calculate the mass of added carbon material and modifier based on the temperature, composition and mass of low basicity casting residue.

[0115] Calculate the amount of carbon material added according to the calculation formula:

[0116]

[0117] Where: M 碳 is the mass of carbon material added, r is the radius of the slag basin liquid surface, k is the carbon combustion coefficient, M 渣 is the mass of the casting slag, η is the attenuation coefficient, T is the end point control temperature, T0 is the initial temperature of the casting slag, ω 碳 is the mass fraction of carbon in carbon materials. Specific values ​​are shown in Table 3-2.

[0118] Table 3-2 Calculation parameters of carbon material addition amount in Example 3

[0119] r / m <![CDATA[k / (kg / m 2 ·s)]]> M 渣 / kg]]> <![CDATA[η / s -1 ]]> 0.95 0.083 3227 -0.207 T / ℃ [T0 / °C] <![CDATA[ω 碳 ]]> M 碳 / kg]]> 400 1547 69.2％ 307

[0120] In this embodiment, the end temperature T is controlled to 400° C., and the mass of carbonized straw added is calculated to be 307 kg. The acidity of the mineral wool raw material is controlled to be 1.5, and the hydrogen ion index is controlled to be 4.

[0121] The modifiers are limestone and dolomite, the effective component of limestone is CaCO3, the effective component of dolomite is CaMg(CO3)2, and the limestone and dolomite are carbonates.

[0122] The amount of modifier added can be obtained by solving the following equations simultaneously. The specific calculation formula is as follows:

[0123]

[0124]

[0125] Where: The quality of SiO2 after modification, is the quality of Al2O3 after modification, W CaO is the mass of CaO after modification, W MgO is the mass of MgO after modification.

[0126] Calculation shows that the mass of dolomite added is 271 kg and the mass of limestone added is 297 kg.

[0127] Further calculations show that the maximum amount of carbon material added is 292 kg, which is less than the 307 kg of carbon material added calculated by S1. In order to ensure that the carbon material is completely burned and does not deteriorate the cotton-forming properties of the mineral wool raw material, the actual amount of carbon material added is 292 kg.

[0128] S2. Add the corresponding mass of carbonized straw, dolomite and limestone calculated in S1 directly into the slag basin, covering the surface of the casting slag. Then move the slag basin to the stirring position, lower the stirring kettle into the casting slag and stir for 2-4 minutes. Then lift the stirring kettle and wait for the casting slag to cool.

[0129] S3. Crushing the cooled casting slag involves coarse crushing and grinding. A PE600*900 jaw crusher is used for coarse crushing, and a YGM7815 high-pressure suspension roller mill is used for grinding. The grinding results in a particle size of less than 50 mesh. MnO and mineral wool are then separated using a 5LL-1500 spiral chute. The separated MnO yielded 594 kg, with a yield of 86.4% and an active ingredient content of 553 kg. The mineral wool yielded 2311 kg, with a yield of 91% and an active ingredient content of 2238 kg. The separated MnO and mineral wool are stored in a warehouse. Both are high-value-added industrial raw materials with high economic value.

[0130] Comparative Example 1

[0131] The present invention relates to high-value-added comprehensive recycling of metallurgical solid waste, simultaneously recovering MnO and mineral wool raw materials from low-alkalinity casting slag. Existing methods for recycling casting slag mostly recover only one valuable material. Taking Anhui Changjiang Iron and Steel Co., Ltd.'s existing process for reforming low-alkalinity casting slag to produce mineral wool raw materials as an example, the process features raw materials consisting of all or part of converter slag, quartz powder, alumina, soda ash, sodium silicate, calcium carbonate, and potassium carbonate, with a weight chemical composition of: converter slag: 40%-90%, quartz powder: 10%-35%, alumina: 5%-15%, soda ash: 5%-25%, sodium silicate: 10%-30%, calcium carbonate: 5%-15%, and potassium carbonate: 5%-15%. During production, the various raw materials are weighed as required; the lumpy raw materials are crushed; the raw materials are placed in a container, mixed, and stirred to uniformize their composition; the uniformly mixed raw materials are placed in a smelting furnace for smelting; and the heating temperature is 800-1600°C, with a holding time of 1-2 hours. Comparison of this method with existing process results in the composition stability and comprehensive economic value of the mineral wool raw materials.

[0132] The low basicity casting slag from 10 consecutive heats of steel mill was selected and treated alternately with this method and the existing process. The acidity and hydrogen ion index of the obtained mineral wool raw materials were compared. Figure 1 and Figure 2 As shown:

[0133] Its acidity and hydrogen ion index are shown in Table 4:

[0134] Table 4 Acidity and hydrogen ion index results of mineral wool raw materials produced in 10 batches

[0135] acidity Heat 1 / 2 Heat 3 / 4 Heat 5 / 6 Heat 7 / 8 Heat 9 / 10 This method 1.47 1.52 1.44 1.49 1.55 Existing process 1.62 1.66 1.53 1.61 1.4 Hydrogen ion index Heat 1 / 2 Heat 3 / 4 Heat 5 / 6 Heat 7 / 8 Heat 9 / 10 This method 3.9 4.1 4.4 3.9 4 Existing process 4.5 4.6 4.1 4.3 4.9

[0136] Statistical data show that the average acidity of this method is 1.494 with a standard deviation of 0.043, while the average acidity of the existing process is 1.564 with a standard deviation of 0.103. The average hydrogen ion index of this method is 4.06 with a standard deviation of 0.207, while the average hydrogen ion index of the existing process is 4.48 with a standard deviation of 0.303. This shows that the composition control precision and stability of the mineral wool raw material produced by this method are superior to those of the existing process. According to the company's financial accounting report on the economic value generated by this method and the existing process, the total value of the products obtained from treating five heats of low-alkalinity casting slag by this method is 3,149 yuan, while the total value of the products obtained from treating five heats of low-alkalinity casting slag by the existing process is 416 yuan.

[0137] The present invention reduces and reforms low-alkalinity casting slag to extract high-value-added MnO and mineral wool raw materials. Compared with the original process, the recovered product has high economic value and the obtained mineral wool raw materials are high-quality and stable, bringing huge economic value to the enterprise.

Claims

1. A production method for extracting manganese oxide from low-alkalinity casting slag and reforming it into mineral wool raw material, characterized in that: The following steps are involved: S1: Calculate the mass of added carbon material and modifier according to the temperature, composition and mass of low basicity casting residue; S2: Add carbon material and modifier to the slag basin, stir for 2-4 minutes and wait for cooling; the modifier is limestone and dolomite; S3: crushing and cooling the low-basicity casting slag, and gravity separation to obtain MnO and mineral wool raw materials; The calculation formula for the amount of carbon material added in step S1 is as follows: Where: M 碳 is the mass of carbon material added, r is the radius of the slag basin liquid surface, k is the carbon combustion coefficient, M 渣 is the mass of the casting slag, η is the attenuation coefficient, T is the end temperature, T0 is the initial temperature of the casting slag, ω 碳 is the mass fraction of carbon in carbon materials; The calculation formula for the amount of modifier added is as follows: Where, is the mass fraction of SiO2 after modification, is the mass fraction of Al2O3 after modification, W CaO is the mass fraction of CaO after modification, W Mgo is the mass fraction of MgO after modification.

2. The method for extracting manganese oxide from low-alkalinity casting slag and reforming it into mineral wool raw material according to claim 1, characterized in that: The low basicity casting slag comprises, by mass fraction, CaO: 18%-24%, SiO2: 32%-46%, Al2O3 12%-20%, MgO: 4%-8%, MnO: 18%-30%, S: 0.02%-0.1%, and P2O5: 0.04%-0.12%. The basicity of the low basicity casting slag is 0.4-0.

6.

3. The method for extracting manganese oxide from low-alkalinity casting slag and reforming it into mineral wool raw material according to claim 2, characterized in that: The calculation formula for the maximum amount of carbon material added is as follows: Where: is the maximum amount of carbon material added, C i is the specific heat capacity of the modifier, M i is the mass of modifier added, △T is the temperature difference before and after the addition of modifier, △H i is the decomposition heat of the modifier, u g is the gas diffusion coefficient, r is the radius of the slag basin, q 碳 is the calorific value of 1kg carbon element, ω 碳 is the mass fraction of carbon in carbon material, and k is the carbon combustion coefficient.

4. The method for extracting manganese oxide from low-alkalinity casting slag and reforming it into mineral wool raw material according to claim 1, characterized in that: The end temperature T is 375-425℃.

5. The method for extracting manganese oxide from low-alkalinity casting slag and reforming it into mineral wool raw material according to claim 1, characterized in that: The carbon material is renewable biochar.

6. The method for extracting manganese oxide from low-alkalinity casting slag and reforming it into mineral wool raw material according to claim 1, characterized in that: The effective component of limestone is CaCO3, and the effective component of dolomite is CaMg(CO3)2.

7. The method for extracting manganese oxide from low-alkalinity casting slag and reforming it into mineral wool raw material according to claim 1, characterized in that: In step S2, the carbon material and modifier of the corresponding mass calculated in step S1 are directly put into the slag basin and covered on the surface of the casting slag. Then, the slag basin is moved to the stirring position, the stirring kettle is lowered and immersed in the casting slag and stirred for 2-4 minutes, and then the stirring kettle is lifted and the casting slag is allowed to cool.

8. The method for extracting manganese oxide from low-alkalinity casting slag and reforming it into mineral wool raw material according to claim 1, characterized in that: The crushing in step S3 includes coarse crushing and grinding, and the particle size of the casting slag after crushing is less than 50 mesh.

9. The method for extracting manganese oxide from low-alkalinity casting slag and reforming it into mineral wool raw material according to claim 8, characterized in that: The low-basicity casting slag obtained by crushing is separated by gravity separation equipment to obtain MnO and mineral wool raw materials.

10. The method for extracting manganese oxide from low-alkalinity casting slag and reforming it into mineral wool raw material according to claim 9, wherein the acidity of the mineral wool raw material is 1.3-1.7 and the hydrogen ion index is less than 5.

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