Method for separate quality utilization of steel slag and slag composite powder

Abstract

The application discloses a kind of steel slag and mineral slag composite powder's separate quality utilization method, comprising the following steps: (1) steel slag, mineral slag raw material is dried, ground, then mixed, to obtain composite powder;(2) the composite powder is mixed with organic acid solution, stirring, then filtration obtains supernatant one and residue;(3) the pH value of supernatant one is adjusted, then aging, so that the silicon aluminum oxide in it forms gel, after solid-liquid separation obtains precipitate one and supernatant two;(4) precipitate one is ground and modified, to obtain nanoscale silicon dioxide / aluminum oxide particles;Supernatant two is made into calcium / magnesium acetate environmentally friendly snow-melting agent by spray drying granulation or heating concentration way.The application can realize steel slag, mineral slag collaborative efficient separate quality utilization, by technical route innovation design, can obtain iron concentrate, nanoscale silicon dioxide / aluminum oxide particles, and calcium / magnesium acetate environmentally friendly snow-melting agent, theoretical utilization rate is close to 100%, with good economic value and social benefits.

Description

Technical Field

[0001] This invention relates to the field of metallurgical waste utilization, specifically to a method for the separate utilization of composite powder of steel slag and ore slag. Background Technology

[0002] Blast furnace slag is a byproduct of ironmaking in steel plants. Alkali-activated slag cementitious materials prepared primarily from blast furnace slag offer significant advantages, including low energy consumption, low cost, excellent performance, and low CO2 emissions. Furthermore, they exhibit excellent resistance to corrosion in high-temperature, sulfate, and acidic environments, making them one of the most promising new cementitious materials to replace ordinary silicate cement. Steel slag, on the other hand, is a solid waste generated during steel smelting. Due to its high content of free calcium oxide and magnesium oxide, its application in concrete and building materials is significantly limited.

[0003] Chemically, both slag and steel slag primarily consist of CaO, SiO2, Al2O3, and MgO, with these four components comprising over 90% of their composition. They also contain small amounts of Fe2O3 and other impurities. Minerally, the main mineral phases in both slag and steel slag are tricalcium silicate, dicalcium silicate, and calcium aluminum silicate. However, slag exhibits a typical glassy structure and has higher hydration reactivity than steel slag.

[0004] Currently, research on slag mainly focuses on the field of cementitious materials. It is used as an admixture in cement production or mixed with materials such as calcium carbide slag and fly ash to form a novel composite cementitious material. Its practical applications are primarily in the construction and mining backfilling industries. For example, Chinese invention patent application number 202110864548.0 proposes a slag concrete with characteristics such as low material cost, easy and simple production, and good concrete performance. However, the hydration reactivity of steel slag is significantly lower than that of slag, resulting in a lower utilization rate in cementitious materials. Related research mainly focuses on concrete and road construction, utilizing steel slag as fine aggregate to replace crushed stone and river sand to enhance the concrete's resistance to carbonation. Chinese invention patent application number 201510176843.1 proposes a steel slag concrete whose various indicators meet the standard requirements of ordinary concrete, and even surpasses ordinary concrete in terms of impermeability and wear resistance. From the current research status, slag and steel slag are mainly used in building materials and road construction, with low added value and intense industry competition. Summary of the Invention

[0005] Based on the above-mentioned technical problems, this invention proposes a method for the separate utilization of composite powder of steel slag and blast furnace slag.

[0006] The technical solution adopted in this invention is:

[0007] A method for the graded utilization of composite powder of steel slag and blast furnace slag includes the following steps:

[0008] (1) Dry and grind steel slag and ore slag raw materials, and then mix them to obtain composite powder;

[0009] (2) Mix the composite powder with the organic acid solution, stir, and then filter to obtain clear liquid and residue;

[0010] (3) Adjust the pH value of the first clear liquid, and then age it to form a gel from the silicon and aluminum oxides. After solid-liquid separation, precipitate one and clear liquid two are obtained.

[0011] (4) Grind and modify precipitate one to obtain nano-sized silica / alumina particles; concentrate clear liquid two into a high-concentration calcium acetate / magnesium salt solution by heating, or granulate by spray drying to produce calcium acetate / magnesium environmentally friendly de-icing agent particles.

[0012] Preferably, in step (1): after grinding, the specific surface area of ​​the slag is controlled to be ≥400m². 2 / kg, steel slag specific surface area ≥500m² 2 / kg.

[0013] Preferably, in step (2): the organic acid solution is one or a mixture of two or more of acetic acid, lactic acid, oxalic acid and tartaric acid solutions.

[0014] Preferably, in step (2): the concentration of the organic acid solution is 0.5–2 mol / L, the solid-liquid ratio of the composite powder to the organic acid solution is 1:8–10, by weight; the stirring time is controlled at 10–60 min, and the reaction temperature is 5–30 °C. More preferably, the mixing and stirring time is 20–40 min, and the reaction temperature is 15–25 °C.

[0015] Preferably, in step (2): the iron oxides in the residue (mainly iron oxides and feldspar) are enriched by magnetic separation equipment and then sold as iron concentrate. The magnetic separation equipment can be a dry or wet magnetic separator such as a flat plate magnetic separator, a magnetic drum, or a vertical ring high gradient magnetic separator, with a magnetic induction intensity of 0.4 to 1.5T.

[0016] Preferably, in step (3): the pH value of the first clear solution is adjusted to 6-9 using ammonia water, and the volume concentration of ammonia water is 1:1-3.

[0017] Preferably, in step (3), the aging temperature is controlled at 20–80°C and the aging time is controlled at 2–8 hours. More preferably, the aging temperature is controlled at 40–60°C and the aging time is controlled at 3–4 hours.

[0018] Preferably, in step (4): the clear liquid is concentrated into a high-concentration calcium acetate / magnesium salt solution by heating, or spray-dried and granulated to produce environmentally friendly calcium acetate / magnesium de-icing agent granules.

[0019] Preferably, the water used in the heating process is condensed by a condenser and then reused in the acid dissolution process of the composite powder and organic acid solution in step (2).

[0020] Preferably, in step (4): the Ca / Mg ratio in the de-icing agent is adjusted by adding calcium oxide, calcium hydroxide, calcium carbonate or magnesium oxide, magnesium hydroxide, magnesium carbonate to the clear liquid, while consuming the remaining organic acid in the clear liquid; the Ca / Mg ratio is controlled to be 4:6 to 2:8.

[0021] The beneficial technical effects of this invention are:

[0022] (1) This invention uses steel slag and ore slag as the main materials. The iron oxides and feldspar impurities are filtered out by organic acid solutions such as acetic acid. Then, high-grade iron concentrate is obtained by simple magnetic separation, which generates certain economic benefits.

[0023] (2) Based on acid dissolution, this invention uses a simple sol-gel method to convert silicon and aluminum elements in slag / steel slag into nano-sized silicon dioxide and aluminum oxide particles, generating higher economic value. Furthermore, acetic acid can be used to utilize waste from the food processing and fermentation industries, achieving high-value recycling of other wastes.

[0024] (3) For calcium and magnesium elements in the solution, an environmentally friendly de-icing agent is prepared by forming calcium acetate / magnesium or other organic acid solutions of calcium / magnesium.

[0025] (4) This invention enables the synergistic and efficient fractional utilization of steel slag and mineral slag. Through innovative technical design, it can produce iron concentrate, nano-sized silica / alumina particles, and environmentally friendly calcium acetate / magnesium de-icing agent, with a theoretical utilization rate of nearly 100%, demonstrating significant economic and social benefits. This invention also boasts advantages such as a simple process flow and low production costs. This invention provides a new approach for the high-value utilization of steel slag and mineral slag.

[0026] (5) The water used in the production process of this invention can be recycled to the acid dissolution mixing process for reuse, resulting in a low overall water consumption. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the process for the graded utilization of composite powder of steel slag and blast furnace slag in Embodiment 1 of the present invention.

[0028] Figure 2 The XRD pattern of the nano-sized silica / alumina particles obtained in Example 1 of this invention;

[0029] Figure 3 The image shows a SEM image of the nano-sized silica / alumina particles obtained in Example 1 of this invention.

[0030] Figure 4 The above refers to the EDS analysis data of the nano-sized silica / alumina particles obtained in Example 1 of this invention;

[0031] Figure 5 The XRD pattern is shown in Example 1 of this invention. Detailed Implementation

[0032] This invention combines the chemical composition and reaction characteristics of steel slag and blast furnace slag, which are rich in SiO2, Al2O3, CaO and MgO, and proposes a synergistic and efficient method for the fractional utilization of steel slag and blast furnace slag composite powder based on the application requirements of combining nano-sized silica or alumina and environmentally friendly de-icing agents.

[0033] As extremely important inorganic materials, nano-sized silica or alumina possesses advantages such as small particle size, numerous micropores, large specific surface area, strong surface adsorption, and high stability, as well as properties such as reinforcing, thickening, and thixotropic effects. They have been widely used in numerous fields including plastics, rubber, ceramics, and coatings. Nano-sized silica and alumina are mainly prepared through methods such as sol-gel and vapor-phase methods.

[0034] Using de-icing agents is the most common method for snow and ice removal. Commonly used de-icing agents mainly include salts and alcohols. In my country, the most commonly used de-icing agents are chloride-based, such as sodium chloride and calcium chloride. While traditional chloride-based de-icing agents have advantages such as good snow-melting and ice-removing performance and low price, they also have a series of environmentally unfriendly problems, including corrosive effects on steel reinforcement and road structures. To reduce the environmental harm caused by chloride-based de-icing agents, an environmentally friendly de-icing agent is needed as an alternative, while retaining its advantages of good performance and low cost. Calcium acetate / magnesium complex is a typical example of an environmentally friendly de-icing agent.

[0035] In this invention, the acidic properties of acetic acid or other similar organic acid solutions are utilized to achieve the synergistic and efficient fractional utilization of steel slag and mineral slag through a series of processes including acid dissolution, gelation, modification, and drying. Its advantage lies in the ability to prepare nano-sized silica and alumina composite particles, which can be used as fillers in rubber and plastic products, resulting in high added value. During this process, the ratio of silica to alumina in the nano-silica and alumina composite particles can be adjusted by modifying the proportion of steel slag and mineral slag. Furthermore, this invention can simultaneously produce a high-performance, environmentally friendly calcium acetate / magnesium acetate de-icing agent. The ratio of calcium acetate to magnesium acetate in the de-icing agent can be adjusted by adding calcium oxide, calcium hydroxide, and calcium carbonate, or magnesium oxide, magnesium hydroxide, and magnesium carbonate.

[0036] The present invention will be further described below with reference to specific embodiments.

[0037] Example 1

[0038] like Figure 1 As shown, a method for the graded utilization of composite powder of steel slag and blast furnace slag includes the following steps:

[0039] (1) Dry and grind the steel slag and ore slag raw materials, and control the specific surface area of ​​the ore slag to be ≥400m². 2 / kg, steel slag specific surface area ≥500m² 2 / kg, and then mixed in a certain proportion to obtain composite powder.

[0040] (2) The composite powder was mixed with an acetic acid solution at a concentration of 2 mol / L, and the solid-liquid ratio of the composite powder to the acetic acid solution was 1:10 by weight. The mixture was then stirred for 40 minutes. The mixture was then filtered to obtain a clear liquid and a residue (mainly composed of iron oxides and feldspar impurities). The residue had a high iron content; therefore, magnetic separation was used to concentrate the iron oxides in the residue before it was sold as iron concentrate.

[0041] (3) Adjust the pH of the first clear liquid to 8 using an ammonia solution with a volume ratio of 1:1, and then age it at a temperature of 60°C for 3 hours. This allows the silica and alumina oxides in the liquid to form a gel. After solid-liquid separation, precipitate one and clear liquid two are obtained.

[0042] (4) Precipitate 1 does not require drying and is directly ground and modified. The modification process involves adding a pre-hydrolyzed (hydrolysis time 24h-48h) silane modifier (KH-550 and A-151 mass ratio of 4:1) to the silica / alumina particles during the grinding process to enhance their compatibility with rubber and plastic products. The mass concentration of the silane modifier is 5%, and the addition amount is 0.5% of the mass of the silica / alumina particles. After grinding and modification, precipitate 1 is spray-dried to obtain nano-sized silica / alumina filler for rubber and plastic products. The Ca / Mg ratio is adjusted by adding calcium oxide or magnesium oxide to clear liquid 2 to control the Ca / Mg ratio at 4:6, and then spray-dried and granulated to produce calcium acetate / magnesium environmentally friendly de-icing agent. The water in the drying process of clear liquid 2 is condensed by a condenser and then reused in the acid dissolution process of the composite powder and organic acid solution.

[0043] The XRD patterns, SEM images, and EDS analysis results of the above-mentioned nano-sized silica / alumina particles are as follows: Figures 2-4 As shown. By Figure 2 It can be seen that the peaks appearing between 15 and 35° at 2θ indicate that the silica / alumina particles have a typical cryptocrystalline structure. Figure 3 It can be seen that the silica / alumina particles exhibit an amorphous morphology, with most particles ranging in size from 100 to 500 nm. Figure 4 EDS analysis results show that the main elemental composition of precipitate one is Si, Al, and O, indicating that the particles are a composite of silicon dioxide and aluminum oxide, with a Si / Al atomic ratio of approximately 6:1. The XRD pattern of the calcium acetate / magnesium environmentally friendly de-icing agent is shown below. Figure 5 As shown in the figure, precipitate II is mainly composed of calcium acetate / magnesium, with no other obvious impurities. BET analysis shows that the specific surface area of ​​the above-mentioned nano-sized silica / alumina particles is 231.16 m². 2 / g.

[0044] Example 2

[0045] A method for the graded utilization of composite powder of steel slag and blast furnace slag includes the following steps:

[0046] (1) Dry and grind the steel slag and ore slag raw materials, and control the specific surface area of ​​the ore slag to be ≥400m². 2 / kg, steel slag specific surface area ≥500m² 2 / kg, and then mixed in a certain proportion to obtain composite powder.

[0047] (2) The composite powder was mixed with an acetic acid solution with a concentration of 0.5 mol / L. The solid-liquid ratio of the composite powder to the acetic acid solution was 1:10, by weight. The mixture was then stirred for 20 minutes. The mixture was then filtered to obtain a clear liquid and a residue (mainly composed of iron oxides and feldspar impurities). The residue had a high iron content. The iron oxides in the residue were enriched using a magnetic separator and then sold as iron concentrate.

[0048] (3) Adjust the pH of the first clear liquid to 7 using an ammonia solution with a volume ratio of 1:3, and then age it at a temperature of 40°C for 6 hours. This allows the silica and aluminum oxides in the liquid to form a gel. After solid-liquid separation, precipitate one and clear liquid two are obtained.

[0049] (4) Precipitate 1 does not require drying and is directly ground and modified. The modification process involves adding a pre-hydrolyzed (hydrolysis time 24h-48h) silane modifier (KH-550 and A-151 mass ratio of 4:1) to the silica / alumina particles during the grinding process to enhance the compatibility of the silica / alumina particles with rubber and plastic products. The mass concentration of the silane modifier is 5%, and the addition amount is 1.5% of the mass of the silica / alumina particles. After grinding and modification, precipitate 1 is spray-dried to obtain nano-sized silica / alumina filler for rubber and plastic products. The Ca / Mg ratio is adjusted by adding calcium oxide or magnesium oxide to the clear liquid 2 to control the Ca / Mg ratio at 2:8. Then, the clear liquid 2 is concentrated to a mass concentration of approximately [missing value] and spray-dried and granulated to produce calcium acetate / magnesium environmentally friendly de-icing agent. The water used in the second drying process of the clear liquid is condensed by a condenser and then reused in the acid dissolution process of the composite powder and organic acid solution.

[0050] Example 3

[0051] A method for the graded utilization of composite powder of steel slag and blast furnace slag includes the following steps:

[0052] (1) Dry and grind the steel slag and ore slag raw materials, and control the specific surface area of ​​the ore slag to be ≥400m². 2 / kg, steel slag specific surface area ≥500m² 2 / kg, and then mixed in a certain proportion to obtain composite powder.

[0053] (2) The composite powder was mixed with an acetic acid solution at a concentration of 1 mol / L, and the solid-liquid ratio of the composite powder to the acetic acid solution was 1:10 by weight. The mixture was then stirred for 30 minutes. The mixture was then filtered to obtain a clear liquid and a residue (mainly composed of iron oxides and feldspar impurities). The residue had a high iron content; therefore, the iron oxides in the residue were enriched using magnetic separation equipment and sold as iron concentrate.

[0054] (3) Adjust the pH of the first clear liquid to 6 using an ammonia solution with a volume ratio of 1:3, and then age it at a temperature of 50°C for 3 hours. This allows the silica and alumina oxides in the liquid to form a gel. After solid-liquid separation, precipitate one and clear liquid two are obtained.

[0055] (4) Precipitate 1 does not require drying and is directly ground and modified. The modification process involves adding a pre-hydrolyzed (hydrolysis time 24h-48h) silane modifier (KH-550 and A-151 mass ratio of 4:1) during the grinding process to enhance the compatibility of silica / alumina particles with rubber and plastic products. The mass concentration of the silane modifier is 5%, and the addition amount is 1% of the mass of the silica / alumina particles. After grinding and modification, precipitate 1 is spray-dried to obtain nano-sized silica / alumina filler for rubber and plastic products. The Ca / Mg ratio is adjusted by adding calcium oxide or magnesium oxide to clear liquid 2 to control the Ca / Mg ratio at 4:8. Then, clear liquid 2 is concentrated into a high-concentration calcium acetate / magnesium salt solution of about 30% by heating. The water in the concentration process of clear liquid 2 is condensed by a condenser and then reused in the acid dissolution process of composite powder and organic acid solution.

[0056] The aforementioned magnetic separation equipment can be one or two of the following: flat plate magnetic separator, magnetic drum, vertical ring high gradient magnetic separator, etc., with a magnetic induction intensity of 0.4 to 1.5T.

[0057] The above-mentioned composite powder is mixed and dissolved with acetic acid solution, and the reaction process, such as adding ammonia water to the clear liquid and aging, can be carried out in a reaction vessel.

[0058] For any parts not mentioned above, existing technologies can be adopted or referenced.

[0059] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for the graded utilization of composite powder of steel slag and blast furnace slag, characterized in that... Includes the following steps: (1) Dry and grind steel slag and ore slag raw materials, and then mix them to obtain composite powder; (2) Mix the composite powder with the organic acid solution, stir, and then filter to obtain clear liquid and residue; (3) Adjust the pH value of the first clear liquid, and then age it to form a gel from the silica and aluminum oxides. After solid-liquid separation, precipitate one and clear liquid two are obtained. (4) The precipitate 1 was ground and modified to obtain nano-sized silica / alumina particles; the clear liquid 2 was spray dried and granulated to produce calcium acetate / magnesium environmentally friendly de-icing agent; In step (2): the iron oxides in the residue are enriched by magnetic separation equipment and then sold as iron concentrate; In step (3): the pH of the first clear liquid is adjusted to 6-9 using ammonia water, and the volume concentration of ammonia water is 1:1-3; the aging temperature is controlled at 20-80℃ and the aging time is 2-8h. In step (4): the clear liquid 2 is concentrated into a high-concentration calcium acetate / magnesium salt solution by heating, or granulated by spray drying to produce calcium acetate / magnesium environmentally friendly de-icing agent granules; the Ca / Mg ratio in the de-icing agent is adjusted by adding calcium oxide, calcium hydroxide, calcium carbonate or magnesium oxide, magnesium hydroxide, magnesium carbonate to the clear liquid 2, while consuming the remaining organic acid in the clear liquid 2; the Ca / Mg molar ratio is controlled to be 4:6 to 2:

8.

2. The method for the fractional utilization of steel slag and blast furnace slag composite powder according to claim 1, characterized in that, In step (1): After grinding, the specific surface area of ​​the slag is controlled to be ≥400m². 2 / kg, steel slag specific surface area ≥500m² 2 / kg.

3. The method for the fractional utilization of steel slag and blast furnace slag composite powder according to claim 1, characterized in that, In step (2): the organic acid solution is one or a mixture of two or more of acetic acid, lactic acid, oxalic acid and tartaric acid solutions.

4. The method for the fractional utilization of steel slag and blast furnace slag composite powder according to claim 1, characterized in that, In step (2): the concentration of the organic acid solution is 0.5-2 mol / L, the solid-liquid ratio of the composite powder to the organic acid solution is 1:8-10, by weight; the stirring time is controlled to be 10-60 min, and the reaction temperature is 5-30℃.

5. The method for the fractional utilization of steel slag and blast furnace slag composite powder according to claim 1, characterized in that: The water used in the heating process is condensed by a condenser and then reused in the acid dissolution process of the composite powder and organic acid solution in step (2).

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