Modified steel slag particles and preparation method thereof

Abstract

The invention provides modified steel slag particles and a preparation method thereof, and the preparation method comprises the following steps: (1) mixing steel slag with acid, standing, and pouring out the acid to obtain pretreated steel slag; and (2) flushing and / or soaking the pretreated steel slag obtained in the step (1) by adopting a solution containing a surfactant, and drying to obtain the modified steel slag particles. The acid soaking process is adopted to catalyze, passivate and eliminate alkaline dissolved substances of the steel slag, and then the steel slag particles are treated after the process of flushing the steel slag with concentrated soapy water. The main component of the soapy water is stearic acid, the stearic acid is used as a common surface modifier and can be combined with the steel slag particles through chemical bonds, so that the surface properties of the steel slag particles are changed, the effect of sealing steel slag pores is achieved, and the modification method is simple in step, low in modification cost and beneficial to subsequent large-scale popularization and application.

Description

Technical Field

[0001] The invention relates to the technical field of steel slag preparation, and in particular to modified steel slag particles and a preparation method thereof. Background Art

[0002] Steel slag is an impurity separated from two mutually insoluble liquid phases melted at high temperature after adding smelting fluxes such as limestone, dolomite and iron ore and slag-making material lime during steelmaking. At present, large steel mills generally produce millions of tons of steel per year, and the output of steel slag is about 15% to 20% of the steel output. However, the effective utilization rate of these industrial wastes in my country is very low at present, and they are usually mainly treated by landfill and yard accumulation. The accumulation of a large amount of steel slag not only brings environmental pollution but also occupies a large amount of fertile land, and causes serious pollution and damage to the surrounding ecological environment. If steel slag can be turned into treasure, it will surely produce huge economic and social benefits. At present, the reuse of steel slag is mainly direct use or as an additive after crushing and refinement, and it is also used after treatment.

[0003] Steel slag has the problem of expansion when it comes into contact with water. The volume expansion of steel slag is mainly due to the hydration reaction of f-CaO, which contains about 5% of the slag in the steel slag system, to generate calcium hydroxide, resulting in a volume expansion of 98%. This leads to insufficient volume stability of the steel slag, thus limiting the scope of use of the steel slag.

[0004] Therefore, it is necessary to modify the steel slag. Currently, there are many patent documents reporting on the preparation methods of modified steel slag particles, mainly the following: (1) CN202311763808.0 A steel slag and its modification method and application, by injecting a modifier into the molten steel slag, and then rapidly cooling, to achieve the effect of modified steel slag; the modifier is a silica-rich material; the steel slag modification temperature is relatively high, and through the rapid cooling reaction, the modification conditions are relatively harsh and the process is complicated; (2) CN202311078315.3 A carbon-coated nitrogen-doped steel slag modified material and its preparation method and application, relating to a carbon-coated nitrogen-doped steel slag modified material and its preparation method and application; the carbon-coated nitrogen-doped steel slag modified material is steel slag and polyvinyl pyrrolidone in a mass ratio of 2-4:1-2; polyvinyl pyrrolidone has a poor effect on improving the water absorption and expansion of steel slag; (3) CN202310494964.5 A steel slag modification method, providing a nano-silicon dioxide dispersion steel slag modification method; soaking the steel slag in the nano-silicon dioxide dispersion; obtaining the soaked steel slag, and drying it to obtain modified steel slag; the cost of the silicon dioxide dispersion is relatively high; (4) CN202310640171.X A device and method for f-CaO digestion of steel slag modification and particle size treatment, providing a device and method for f-CaO digestion of steel slag modification and particle size treatment, the equipment used for steel slag modification is relatively large and the process is complicated.

[0005] Therefore, there is an urgent need to provide a method for preparing modified steel slag particles with low water absorption and low f-CaO content using a simple process. Summary of the invention

[0006] In view of the above-mentioned shortcomings of the prior art, the object of the present invention is to provide a modified steel slag particle and a preparation method thereof, so as to solve the problem of complex steel slag modification process in the prior art.

[0007] To achieve the above objectives and other related objectives, the present invention is achieved through the following technical solutions.

[0008] The first aspect of the present invention is to provide a method for preparing modified steel slag particles, the preparation method comprising the following steps:

[0009] (1) mixing steel slag with acid, allowing the mixture to stand, and then pouring out the acid to obtain pretreated steel slag; (2) washing the pretreated steel slag obtained in step (1) with a solution containing a surfactant and / or drying the pretreated steel slag to obtain modified steel slag particles.

[0010] The second aspect of the present invention is to provide a modified steel slag particle, which is prepared by the above-mentioned preparation method of the modified steel slag particle.

[0011] As described above, the modified steel slag particles and the preparation method thereof of the present invention have the following beneficial effects:

[0012] (1) The method provided by the present invention can reduce the alkaline substances and other impurities in steel slag, improve the microstructure of steel slag particles, seal the pores on the surface of steel slag particles, change the original hydrophilic structure into a hydrophobic structure, reduce the internal pores of steel slag, and improve the stability of steel slag.

[0013] (2) The preparation method of the modified steel slag particles of the present invention mainly adopts an acid soaking process to catalyze and passivate the elimination of alkaline dissolution of the steel slag, and then uses concentrated soapy water to wash the steel slag to post-treat the steel slag particles. The main component of the soapy water is stearic acid. As a commonly used surface modifier, stearic acid can be combined with steel slag particles through chemical bonds, thereby changing the surface properties of the steel slag particles and playing a role in closing the pores of the steel slag.

[0014] (3) The modification method of the modified steel slag particles of the present invention has simple steps and low modification cost, which is conducive to subsequent large-scale promotion and application. DETAILED DESCRIPTION

[0015] In order to make the purpose of the invention, technical solutions and beneficial technical effects of the present invention clearer, the present invention is further described in detail below in conjunction with embodiments. People familiar with this technology can easily understand other advantages and effects of the present invention from the contents disclosed in this specification.

[0016] The extended part of this application and the effect description of the extended part, including but not limited to subsequent data analysis, mechanism description, etc.

[0017] The first aspect of the present invention is to provide a method for preparing modified steel slag particles, the preparation method comprising the following steps:

[0018] (1) mixing steel slag with acid, allowing the mixture to stand, and pouring out the acid to obtain pretreated steel slag; (2) washing the pretreated steel slag obtained in step (1) with a solution containing a surfactant, and drying the mixture to obtain modified steel slag particles.

[0019] In some embodiments of the present invention, the solution containing a surfactant in step (2) is a substance containing stearic acid and / or sodium stearate. Preferably, the substance containing stearic acid and / or sodium stearate is soapy water.

[0020] In some embodiments of the present invention, the mass percentage concentration of the solution containing the surfactant in step (2) is 15-30%. Specifically, the mass percentage concentration can be 15-18%, 18-20%, 20-22%, 22-30%; typically but not limited to, for example, 15%, 18%, 20%, 22%, 30%.

[0021] The present invention mainly uses dilute hydrochloric acid soaking and concentrated soap water washing to treat steel slag particles. After the steel slag particles are soaked in acid, the original alkaline substances are neutralized or precipitated, and the content of alkaline substances such as f-CaO in the steel slag is reduced, which is convenient for improving the stability of the steel slag and is conducive to the subsequent resource recycling of the steel slag; in addition, after the steel slag is pretreated by washing with concentrated soap water, the sodium stearate in the soap water can improve the microstructure of the steel slag particles. From a microscopic perspective, a protective film is formed on the surface of the steel slag particles, and the original hydrophilic surface becomes a hydrophobic surface, which not only blocks the external water from reacting with the alkaline substances in the steel slag particles, but also blocks the harmful substances inside the steel slag from diffusing to the outside, effectively reducing the water absorption rate of the steel slag, inhibiting its expansion, and thus improving the stability of the modified steel slag particles.

[0022] In some embodiments of the present invention, the main component of the soap water is sodium stearate, and its molecular formula is C17H35COONa. Soap is a general term for fatty acid metal salts. The carbon number of fatty acids in daily soaps is generally 10-18. The metal is mainly alkali metals such as sodium or potassium. There are also special-purpose soaps made of ammonia and certain organic bases such as ethanolamine and triethanolamine. Soaps include laundry soaps, perfumed soaps, metal soaps, liquid soaps, and related products such as fatty acids, hardened oils, and glycerin. Ingredients of soap: sodium salt of carboxylic acid R-CO2Na, synthetic pigments, synthetic fragrances, preservatives, antioxidants, foaming agents, hardeners, thickeners, and synthetic surfactants.

[0023] Sodium stearate, as a commonly used surface modifier, combines with steel slag particles through chemical bonds, so that the stearic acid on the surface of the steel slag reaches a monolayer coverage, and the hydrophobic group of stearic acid faces outward, thus achieving the modification effect.

[0024] In some embodiments of the present invention, the steel slag in step (1) is selected from electric furnace slag or converter slag.

[0025] In some specific embodiments of the present invention, the electric furnace slag is Baosteel electric furnace slag.

[0026] In some specific embodiments of the present invention, the converter slag is Baosteel converter slag.

[0027] In some embodiments of the present invention, the steel slag in step (1) is dried, cooled and screened. Specifically, the steel slag is placed in an oven, and after the steel slag is dried to a constant weight, the oven is closed. After the raw materials are cooled to room temperature, the steel slag particles are screened out for use. The drying temperature is 85-95°C. The drying temperature can be 85-90°C, 90-95°C; typically but not restrictively, for example, 85°C, 90°C, 95°C. The particle size of the steel slag is 3-15mm, and preferably, the particle size of the steel slag is 5-10mm.

[0028] In some embodiments of the present invention, the mixing method in step (1) is impregnation, and the impregnation is equal volume impregnation or excess impregnation. Preferably, the impregnation is excess impregnation, specifically, the acid is submerged in the steel slag.

[0029] In some embodiments of the present invention, the acid in step (1) is an organic acid or an inorganic acid;

[0030] In some specific embodiments of the present invention, the inorganic acid is selected from any one of dilute hydrochloric acid, dilute sulfuric acid, hydrofluoric acid and dilute nitric acid.

[0031] In some specific embodiments of the present invention, the organic acid is selected from any one of aliphatic carboxylic acid, aromatic carboxylic acid and sulfonic acid.

[0032] In some specific embodiments of the present invention, the mass ratio of the acid to water is 1:(40-45).

[0033] In some embodiments of the present invention, the standing time in step (1) is ≥12 hours. The standing time can be 12-13 hours, 13-14 hours, 14-23 hours, 23-24 hours, 24-26 hours, 26-80 hours, 80-95 hours, 95-96 hours, 96-98 hours; typically but not limitedly, for example, 12 hours, 13 hours, 24 hours, 80 hours, 96 hours.

[0034] In some embodiments of the present invention, the rinsing time in step (2) is ≥5 min. The rinsing time can be 5-10 min, 10-20 min, 20-30 min, typically but not limited to, for example, 5 min, 10 min, 20 min, 30 min.

[0035] The second aspect of the present invention is to provide a modified steel slag particle, which is prepared by the above-mentioned preparation method of the modified steel slag particle.

[0036] The present invention is further described below by way of examples, but the scope of the present invention is not limited thereto.

[0037] When the embodiment gives a numerical range, it should be understood that, unless otherwise specified in the present invention, the two endpoints of each numerical range and any numerical value between the two endpoints can be selected. Unless otherwise defined, all technical and scientific terms used in the present invention have the same meaning as those generally understood by those skilled in the art. If specific conditions are not specified in the embodiment, they are carried out according to normal conditions or conditions recommended by the manufacturer. If the manufacturer is not specified for all reagents or instruments, they are conventional products that can be purchased commercially. In addition to the specific methods, equipment, and materials used in the embodiments, according to the grasp of the prior art by those skilled in the art and the record of the present invention, any method, equipment, and material of the prior art similar or equivalent to the method, equipment, and material in the embodiments of the present invention can also be used to realize the present invention.

[0038] Example

[0039] Example 1

[0040] The method for preparing the modified steel slag particles of this embodiment comprises the following steps:

[0041] (1) placing steel slag in an oven, baking at 90° C. until the steel slag has a constant weight, and then closing the oven; after the raw materials are cooled to room temperature, screening out 10 kg of steel slag particles of 5-10 mm for standby use; mixing the standby steel slag with acid, standing, and pouring out the acid to obtain pretreated steel slag; the steel slag is converter slag; the acid is dilute hydrochloric acid, which is a mixture of hydrochloric acid and water in a mass ratio of 1:41; the mixing method is impregnation mixing, and the impregnation method is excessive impregnation; the standing time is 12 hours;

[0042] (2) The pretreated steel slag obtained in step (1) is rinsed with a solution containing a surfactant, and then dried to obtain modified steel slag particles. The solution containing a surfactant is concentrated soap water, the soap manufacturer is Shanghai Soap Co., Ltd., and the concentration of the concentrated soap water is 20%; the rinsing time is 5 minutes, and the drying temperature is 90°C.

[0043] Example 2

[0044] The preparation method of modified steel slag particles in this embodiment is different from that in Embodiment 1 in that the standing time in step (1) is 24 hours.

[0045] Example 3

[0046] The method for preparing modified steel slag particles in this embodiment is different from that in Embodiment 1 in that the standing time in step (1) is 96 hours.

[0047] Example 4

[0048] The method for preparing modified steel slag particles in this embodiment is different from that in Embodiment 1 in that the steel slag is electric furnace slag.

[0049] Example 5

[0050] The preparation method of modified steel slag particles in this embodiment is different from that in Embodiment 4 in that the standing time is 24 hours.

[0051] Example 6

[0052] The preparation method of modified steel slag particles in this embodiment is different from that in Embodiment 4 in that the standing time is 96 hours.

[0053] Comparative Example

[0054] Comparative Example 1

[0055] The steel slag in this comparative example is converter slag, and the converter slag is Baosteel converter slag, which has not been treated.

[0056] Performance Testing

[0057] The modified steel slag particles prepared in Examples 1-6 were taken to test the particle gradation, f.CaO content, and water absorption of the steel slag before and after modification. The test results of the particle gradation of the steel slag before and after modification are shown in Table 1; the test results of the particle gradation, f.CaO content, and water absorption of the steel slag before and after modification are shown in Table 2. Among them, the free calcium content of the modified steel slag was measured by the test method in GB / T 38216.3-2023 "Determination of free calcium oxide content in steel slag by EDTA titration and thermogravimetric analysis"; the particle gradation and water absorption were measured by the test method in JTGE42-2005 "Testing procedures for aggregates for highway engineering".

[0058] The modified steel slag particles prepared in Example 1 and the converter slag of Comparative Example 1 were taken to test the compressive strength of the converter slag. The test standard for the compressive strength is JTG E42-2005 "Test Procedures for Aggregates in Highway Engineering". The test results are shown in Table 3.

[0059] Table 1 Particle size performance test of modified steel slag particles before and after modification in Example 1-6

[0060]

[0061] Table 2 Test on water absorption rate change and CaO content change of steel slag before and after modification in Example 1-6

[0062]

[0063] Table 3 Compressive strength changes of steel slag particles before and after modification in Example 1 and Comparative Example 1

[0064] 3d compressive strength / MPa 7d compressive strength / MPa 28 compressive strength / MPa Comparative Example 1: Steel slag before modification 19.40 30.38 34.65 Example 1 Modified steel slag 17.48 24.45 32.05

[0065] In combination with Examples 1-3 and the data in Tables 1 and 2, it can be seen that when the converter slag is soaked in dilute hydrochloric acid for 12 h, 24 h, and 96 h, respectively, the particle size is reduced to varying degrees, and the f.CaO content after modification is less than the f.CaO content before modification, and the water absorption rate of the converter slag particles before modification is less than the water absorption rate of the converter slag after modification.

[0066] In combination with Examples 4-6 and the data in Tables 1 and 2, it can be seen that when the electric furnace slag is soaked in dilute hydrochloric acid for 12 h, 24 h, and 96 h, respectively, the particle size is reduced to varying degrees, and the f.CaO content after modification is less than the f.CaO content before modification, and the water absorption rate of the electric furnace slag particles before modification is less than the water absorption rate of the converter slag after modification.

[0067] Combining Example 1 and Comparative Example 1, and combining the data in Table 3, it can be seen that the compressive strength of the modified steel slag does not decrease significantly.

[0068] The f.CaO content in converter slag is significantly higher than that in electric furnace slag, so the decrease in its content is more obvious in converter slag and has more reference significance. The water absorption rate of slag particles is also significantly lower than that before modification, which improves the expansion caused by water absorption during the utilization of slag. The slag particles are not significantly broken after being soaked in dilute hydrochloric acid and washed with concentrated soap water, which will not have an adverse effect on the subsequent resource utilization of slag particles.

[0069] In combination with Examples 1-6 of the present invention, and in combination with the data in Tables 1 and 2, it can be seen that the method of the present invention is effective in modifying steel slag particles. After modification, the steel slag particles have better stability, and the reduction of harmful substances is more conducive to the protection of the original environment during resource utilization, preventing alkaline substances from seeping out and harming the natural environment such as soil and water quality.

[0070] The above embodiments are merely illustrative of the principles and effects of the present invention, and are not intended to limit the present invention. Anyone familiar with the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by a person of ordinary skill in the art without departing from the spirit and technical concept disclosed by the present invention shall still be covered by the claims of the present invention.

Claims

1. A method for preparing modified steel slag particles, characterized in that: The preparation method comprises the following steps: (1) mixing steel slag with acid, allowing the mixture to stand, and pouring out the acid to obtain pretreated steel slag; and (2) washing and / or soaking the pretreated steel slag obtained in step (1) with a solution containing a surfactant, and drying the mixture to obtain modified steel slag particles.

2. The method for preparing modified steel slag particles according to claim 1, characterized in that: The step (1) also includes one or more of the following features: 11) The steel slag in step (1) is dried, cooled and screened; 12) The acid in step (1) is an organic acid or an inorganic acid; 13) The mixing method in step (1) is impregnation, and the impregnation is equal volume impregnation or excess impregnation.

3. The method for preparing modified steel slag particles according to claim 2, characterized in that: Also includes any of the following features: 111) The drying temperature is 85-95° C.; 121) The inorganic acid is selected from any one of dilute hydrochloric acid, dilute sulfuric acid, hydrofluoric acid and dilute nitric acid; 122) The organic acid is selected from any one of aliphatic carboxylic acid, aromatic carboxylic acid and sulfonic acid.

4. The method for preparing modified steel slag particles according to claim 1, characterized in that: The standing time in the step (1) is ≥12h.

5. The method for preparing modified steel slag particles according to claim 1, characterized in that: The steel slag in step (1) is selected from electric furnace slag or converter slag.

6. The method for preparing modified steel slag particles according to claim 1, characterized in that: The particle size of the steel slag in step (1) is 3-15 mm.

7. The method for preparing modified steel slag particles according to claim 1, characterized in that: The step (2) also includes one or more of the following features: 21) The solution containing a surfactant in step (2) is a substance containing stearic acid and / or sodium stearate. Preferably, the substance containing stearic acid and / or sodium stearate is soapy water; 22) The mass percentage concentration of the solution containing the surfactant in step (2) is 15-30%; 23) The drying temperature in step (2) is 85-95°C.

8. The method for preparing modified steel slag particles according to claim 1, characterized in that: The soap in the soap water in step (2) is selected from one or more of laundry soap, toilet soap, metal soap and liquid soap.

9. The method for preparing modified steel slag particles according to claim 1, characterized in that: The flushing time in step (2) is ≥5 min.

10. A modified steel slag particle, characterized in that: The modified steel slag particles are prepared by the preparation method of any one of claims 1 to 9.

Images