Diversified utilization method of steel slag resources

Abstract

The invention discloses a method for diversified utilization of steel slag resources, and belongs to the technical field of metallurgical resource reutilization. According to the method, acid leaching separation and precipitation are carried out on the steel slag, different precipitation products are obtained by sequentially changing lixivium, and different elements of the converter steel slag are effectively separated. The utilization rate of the steel slag is greatly increased, and the phenomenon of resource waste is effectively avoided.

Description

Technical Field

[0001] The invention belongs to the technical field of metallurgical resource recycling, and specifically relates to a method for diversified utilization of steel slag resources. Background Art

[0002] Converter slag is waste slag produced in the converter steelmaking process. It mainly comes from the oxides formed by the oxidation of elements contained in molten iron and scrap steel, impurities brought in by metal charge, added slag-making agent, oxidant, desulfurization products and corroded lining materials. The purpose of converter slag making is to meet the needs of molten steel dephosphorization. It is precisely because the converter final slag contains harmful impurities such as phosphorus pentoxide and silicon dioxide that it cannot be returned to the converter for reuse. Although technologies such as converter slag retention technology and low-slag smelting technology have reduced the emission of converter slag, a large amount of converter slag is still produced every year. Due to the high basicity of converter slag (above 3.0) and the high content of free calcium oxide and free magnesium oxide in the slag (greater than 3%), it cannot be used as a cement base like blast furnace slag without special treatment. If the stability of the slag cannot be well controlled, it cannot even be used as a paving material.

[0003] With the rapid development of the steel industry, the amount of steel slag has increased, and the "zero emission" of steel slag has become an important issue for the steel industry to follow the path of circular economy and achieve sustainable development. Therefore, the effective and reasonable use of solid waste generated in the steel smelting process has become an urgent problem for major steel companies. Summary of the invention

[0004] In order to solve the problems of the prior art, the present invention provides a method for diversified utilization of steel slag resources, which carries out acid leaching separation and precipitation on the steel slag for magnetic separation and iron extraction, and sequentially changes the leaching liquid to obtain different precipitation products, thereby effectively separating different elements of converter steel slag. The present invention greatly improves the utilization rate of steel slag and effectively avoids the occurrence of resource waste.

[0005] The purpose of the present invention is achieved through the following technical solutions:

[0006] A method for diversified utilization of steel slag resources, the method comprising the following steps:

[0007] (1) mixing the crushed and ground steel slag with water to obtain slurry;

[0008] (2) adding chloric acid to the ore pulp obtained in step (1) to control the pH value thereof to 2.0-3.0, thereby obtaining an acid leaching solution; heating and stirring the acid leaching solution at a heating temperature of 40-60° C., a reaction time of 0.5-2 h, and a stirring speed of 50-200 r / min, thereby improving the kinetic conditions of the acid leaching reaction, thereby promoting the dissolution of the dicalcium silicate phase.

[0009] (3) After acid leaching, the acid leaching product obtained in step (2) is filtered and separated to obtain a leachate A and a precipitate A. Due to the dissolution and separation of the dicalcium silicate phase in the converter slag, the precipitate A is mainly composed of dicalcium ferrite and can be returned as an iron material for smelting.

[0010] (4) adding lime slurry to the leachate A obtained in step (3) to increase the pH value of the solution to 6.5-7.0, and performing heating operation, the reaction temperature is 40-60° C., the reaction time is 1-1.5 h, and leachate B and precipitate B are obtained. Since calcium phosphate salts are gradually precipitated, precipitate B is mainly composed of calcium phosphate salts and can be used as a phosphate fertilizer.

[0011] (5) The leachate B obtained in step (4) is further added with lime slurry to increase the pH value of the solution to 7.5-8.5, and the heating is continued at a reaction temperature of 40-60° C. for a reaction time of 1-1.5 h to obtain a leachate C and a precipitate C, at which time silicate begins to precipitate, and the main component of the precipitate C is silicate.

[0012] (6) The precipitate C obtained in step (5) is mixed with quartz and soda ash, and fired in a high-temperature furnace at 1050-1100° C. for 0.5-1 h to prepare a glass product.

[0013] (7) The leachate C obtained in step (5) is a calcium chloride aqueous solution, which can be used as an auxiliary raw material, road deicing agent and desiccant raw material in the cement industry.

[0014] Furthermore, in step (1), the particle size of the crushed and ground steel slag is in the range of 0.01 to 0.27 mm.

[0015] Furthermore, in step (1), the ratio of the crushed and ground steel slag to water is 1 g: 100-300 mL.

[0016] Furthermore, in step (1), the steel slag is converter steel slag, which is waste slag produced in the converter steelmaking process; preferably, the steel slag after magnetic separation, which contains the following main components: CaO content of 40% to 60%, SiO2 content of 15% to 25%, FeO x The content is 18% to 25% and the P2O5 content is 1% to 3%.

[0017] Furthermore, in step (6), the mass ratio of the precipitate C to quartz and soda ash is 5-7:1-3:1-3; for example, in terms of mass percentage, the precipitate C: 50%-70%, the quartz: 10%-30%, and the soda ash: 10%-30%.

[0018] The main mineral phases of converter slag are dicalcium ferrite, dicalcium silicate, iron-rich phase and RO phase. The iron-rich phase can be recovered by crushing and magnetic separation; dicalcium ferrite, dicalcium silicate and RO phase are separated by different solubility in water, wherein dicalcium ferrite and RO phase are insoluble in water, while dicalcium silicate is soluble in water. The dephosphorization product tricalcium phosphate is mainly distributed in the dicalcium silicate phase. Therefore, the present invention separates the components of converter slag, and the resources are comprehensively utilized.

[0019] Compared with the prior art, the present invention has the following beneficial technical effects:

[0020] (1) The present invention proposes a method for diversified utilization of steel slag resources, which converts stockpiled steel slag into industrial products, improves the utilization rate of steel slag, avoids waste of resources, has great economic and social benefits, and has good application prospects.

[0021] (2) The present invention directly uses steel slag as raw material, has low requirements on the quality of steel slag, avoids oxidation or reduction of steel slag, and reduces the cost of early pretreatment.

[0022] (3) The present invention first proposes to use chloric acid as a solvent, which can remove Fe 2+ Oxidized to Fe 3+ , and promote the Fe 3+ Precipitation can then assist in the effective separation of the elements in the slag, thus avoiding the waste of energy and resources caused by secondary heating of the slag.

[0023] (4) The present invention fully utilizes steel slag, performs step-by-step extraction according to the characteristics of steel slag components, and prepares different products, thus opening up a new path for the comprehensive utilization of steel slag.

[0024] (5) The present invention does not generate any waste, and all intermediate products can be recycled and consumed. DETAILED DESCRIPTION

[0025] The following non-limiting embodiments may enable a person skilled in the art to more fully understand the present invention, but are not intended to limit the present invention in any way.

[0026] In the following examples, converter slag from a steel plant was used for the test. The chemical composition of the slag is shown in Table 1.

[0027] Table 1 Chemical composition of converter slag in the embodiment (mass fraction / %)

[0028] CaO <![CDATA[SiO2]]> FeO <![CDATA[Fe2O3]]> <![CDATA[P2O5]]> <![CDATA[Al2O3]]> MnO MgO 44.19 19.33 10.96 10.20 1.72 4.99 2.26 5.91

[0029] Example 1

[0030] The steel slag is processed by the method for diversified utilization of steel slag resources of the present invention, and the processing steps are as follows:

[0031] (1) Crushing and grinding steel slag to a particle size in the range of 0.01 to 0.27 mm, mixing 1 g of steel slag with 100 mL of water to prepare a slurry, and adding chloric acid dropwise to control the pH value to 3.0 to prepare an acid leaching solution. The acid leaching solution was heated and stirred at a heating temperature of 50°C, a reaction time of 1 h, and a stirring speed of 50 r / min.

[0032] (2) After acid leaching, the acid leaching obtained in step (1) is filtered and separated to obtain a leachate A and a precipitate A. The leaching rate of iron in the leachate A is 2.41%, and the precipitate A is mainly composed of dicalcium ferrite, which can be returned to smelting as an iron material. Its chemical composition is shown in Table 2.

[0033] Table 2 Chemical composition of precipitate A in Example 1 (mass fraction / %)

[0034] CaO <![CDATA[SiO2]]> FeO <![CDATA[Fe2O3]]> <![CDATA[P2O5]]> <![CDATA[Al2O3]]> MnO MgO 25.12 0.81 0.28 59.04 0.142 2.62 5.06 5.76

[0035] (3) The leachate A obtained in step (2) is added to lime slurry to increase the pH value of the solution to 6.6, and a heating operation is performed. The reaction temperature is 50° C. and the reaction time is 1.5 h to obtain leachate B and precipitate B. The precipitate B is mainly composed of calcium phosphate and can be used as a phosphate fertilizer. Its chemical composition is shown in Table 3.

[0036] Table 3 Chemical composition of precipitate B in Example 1 (mass fraction / %)

[0037] CaO <![CDATA[SiO2]]> <![CDATA[Fe2O3]]> <![CDATA[P2O5]]> <![CDATA[Al2O3]]> MgO 19.39 54.51 2.61 20.03 0.10 1.68

[0038] (4) The leachate B obtained in step (3) was further added with lime slurry to increase the pH value of the solution to 7.5, and the solution was further heated at a reaction temperature of 50° C. for a reaction time of 1 h to obtain a leachate C and a precipitate C. At this time, the main component of the precipitate C was silicate, and its chemical composition was shown in Table 4.

[0039] Table 4 Chemical composition of precipitate C in Example 1 (mass fraction / %)

[0040] CaO <![CDATA[SiO2]]> <![CDATA[Fe2O3]]> <![CDATA[P2O5]]> <![CDATA[Al2O3]]> MgO 17.71 65.94 0.32 1.35 0.52 8.43

[0041] (5) The precipitate C obtained in step (4) is mixed with quartz and soda ash in a mass ratio of 6:2:2, and fired in a high-temperature furnace at 1050° C. for 1 h to prepare a glass product.

[0042] (6) The leachate C obtained in step (4) is a calcium chloride aqueous solution, which can be used as an auxiliary raw material, road deicing agent and desiccant raw material in the cement industry.

[0043] Example 2

[0044] The steel slag is processed by the method for diversified utilization of steel slag resources of the present invention, and the processing steps are as follows:

[0045] (1) Crushing and grinding steel slag to a particle size in the range of 0.01 to 0.27 mm, mixing 1 g of steel slag with 300 mL of water to prepare a slurry, and adding chloric acid dropwise to control the pH value to 2.0 to prepare an acid leaching solution. The acid leaching solution is heated and stirred at a heating temperature of 60°C, a reaction time of 0.5 h, and a stirring speed of 200 r / min.

[0046] (2) After acid leaching, the acid leaching obtained in step (1) is filtered and separated to obtain a leachate A and a precipitate A. The leaching rate of iron in the leachate A is 2.33%, and the precipitate A is mainly composed of dicalcium ferrite, which can be returned to smelting as an iron material. Its chemical composition is shown in Table 5.

[0047] Table 5 Chemical composition of precipitate A in Example 2 (mass fraction / %)

[0048] CaO <![CDATA[SiO2]]> FeO <![CDATA[Fe2O3]]> <![CDATA[P2O5]]> <![CDATA[Al2O3]]> MnO MgO 23.26 0.71 0.21 61.34 0.161 2.35 5.73 5.23

[0049] (3) The leachate A obtained in step (2) is added to lime slurry to increase the pH value of the solution to 6.5, and a heating operation is performed. The reaction temperature is 60° C. and the reaction time is 1.5 h to obtain leachate B and precipitate B. The precipitate B is mainly composed of calcium phosphate and can be used as a phosphate fertilizer. Its chemical composition is shown in Table 6.

[0050] Table 6 Chemical composition of precipitate B in Example 2 (mass fraction / %)

[0051] CaO <![CDATA[SiO2]]> <![CDATA[Fe2O3]]> <![CDATA[P2O5]]> <![CDATA[Al2O3]]> MgO 20.33 54.68 2.33 19.78 0.08 2.03

[0052] (4) The leachate B obtained in step (3) was further added with lime slurry to increase the pH value of the solution to 8.5, and the solution was further heated at a reaction temperature of 60° C. for a reaction time of 1 h to obtain leachate C and precipitate C. At this time, the main component of precipitate C was silicate, and its chemical composition was shown in Table 7.

[0053] Table 7 Chemical composition of precipitate C in Example 2 (mass fraction / %)

[0054] CaO <![CDATA[SiO2]]> <![CDATA[Fe2O3]]> <![CDATA[P2O5]]> <![CDATA[Al2O3]]> MgO 18.06 66.41 0.25 1.21 0.45 7.66

[0055] (5) The precipitate C obtained in step (4) is mixed with quartz and soda ash in a mass ratio of 5:2:3, and fired in a high-temperature furnace at 1100° C. for 1 hour to prepare a glass product.

[0056] (6) The leachate C obtained in step (4) is a calcium chloride aqueous solution, which can be used as an auxiliary raw material, road deicing agent and desiccant raw material in the cement industry.

[0057] Example 3

[0058] The steel slag is processed by the method for diversified utilization of steel slag resources of the present invention, and the processing steps are as follows:

[0059] (1) Crushing and grinding the steel slag to a particle size in the range of 0.01 to 0.27 mm, mixing 1 g of the steel slag with 200 mL of water to prepare a slurry, and adding chloric acid dropwise to control the pH value to 2.5 to prepare an acid leaching solution. The acid leaching solution was heated and stirred at a heating temperature of 40°C, a reaction time of 2 h, and a stirring speed of 100 r / min.

[0060] (2) After acid leaching, the acid leaching obtained in step (1) is filtered and separated to obtain a leachate A and a precipitate A. The leaching rate of iron in the leachate A is 2.39%, and the precipitate A is mainly composed of dicalcium ferrite, which can be returned to smelting as an iron material. Its chemical composition is shown in Table 8.

[0061] Table 8 Chemical composition of precipitate A in Example 3 (mass fraction / %)

[0062] CaO <![CDATA[SiO2]]> FeO <![CDATA[Fe2O3]]> <![CDATA[P2O5]]> <![CDATA[Al2O3]]> MnO MgO 25.12 0.81 0.28 59.04 0.142 2.62 5.06 5.76

[0063] (3) The leachate A obtained in step (2) is added to lime slurry to increase the pH value of the solution to 7.0, and a heating operation is performed. The reaction temperature is 40° C. and the reaction time is 1 h to obtain leachate B and precipitate B. The precipitate B is mainly composed of calcium phosphate and can be used as a phosphate fertilizer. Its chemical composition is shown in Table 9.

[0064] Table 9 Chemical composition of precipitate B in Example 3 (mass fraction / %)

[0065] CaO <![CDATA[SiO2]]> <![CDATA[Fe2O3]]> <![CDATA[P2O5]]> <![CDATA[Al2O3]]> MgO 20.00 55.32 2.01 20.5 0.08 1.79

[0066] (4) The leachate B obtained in step (3) was further added with lime slurry to increase the pH value of the solution to 7.8, and the solution was further heated at a reaction temperature of 40° C. for a reaction time of 1.5 h to obtain leachate C and precipitate C. At this time, the main component of precipitate C was silicate, and its chemical composition was shown in Table 10.

[0067] Table 10 Chemical composition of precipitate C in Example 3 (mass fraction / %)

[0068] CaO <![CDATA[SiO2]]> <![CDATA[Fe2O3]]> <![CDATA[P2O5]]> <![CDATA[Al2O3]]> MgO 18.93 67.31 0.27 1.37 0.61 7.89

[0069] (5) The precipitate C obtained in step (4) is mixed with quartz and soda ash in a mass ratio of 7:3:1, and fired in a high-temperature furnace at 1075° C. for 1 hour to prepare a glass product.

[0070] (6) The leachate C obtained in step (4) is a calcium chloride aqueous solution, which can be used as an auxiliary raw material, road deicing agent and desiccant raw material in the cement industry.

Claims

1. A method for diversified utilization of steel slag resources, characterized in that: The steps include: (1) mixing the crushed and ground steel slag with water to obtain slurry; (2) adding chloric acid to the ore pulp obtained in step (1), controlling the pH value to 2.0-3.0, and obtaining an acid leaching solution; heating and stirring the acid leaching solution at a temperature of 40-60° C. for a time of 0.5-2 h; (3) filtering and separating the acid leaching solution obtained in step (2) to obtain a leachate A and a precipitate A; (4) adding lime slurry to the leachate A obtained in step (3), controlling the pH value to 6.5-7.0, and performing a heating operation at a temperature of 40-60° C. for a time of 1-1.5 h to obtain a leachate B and a precipitate B; (5) adding lime slurry to the leachate B obtained in step (4), controlling the pH value to 7.5-8.5, and performing a heating operation at a temperature of 40-60° C. for 1-1.5 h to obtain a leachate C and a precipitate C; (6) mixing the precipitate C obtained in step (5) with quartz and soda ash, and firing at 1050-1100° C. for 0.5-1 h to prepare a glass product; (7) The leachate C obtained in step (5) is a calcium chloride aqueous solution.

2. The method according to claim 1, characterized in that In step (1), the slag is converter slag.

3. The method according to claim 1, characterized in that In step (1), the steel slag is the steel slag after magnetic separation and iron extraction.

4. The method according to claim 1, characterized in that In step (1), the particle size of the crushed and ground steel slag is 0.01 to 0.27 mm.

5. The method according to claim 1, characterized in that: In step (1), the ratio of the crushed and ground steel slag to water is 1 g: 100-300 mL.

6. The method according to claim 1, characterized in that In step (2), the stirring speed is 50 to 200 r / min.

7. The method according to claim 1, characterized in that In step (3), the precipitate A is returned to smelting as iron material.

8. The method according to claim 1, characterized in that In step (4), the precipitate B is used as a phosphate fertilizer.

9. The method according to claim 1, characterized in that: In step (6), the mass ratio of the precipitate C to quartz and soda ash is 5-7:1-3:1-3.

10. The method according to claim 1, characterized in that In step (7), the leachate C is used as an auxiliary raw material, road deicing agent and desiccant raw material in the cement industry.