Preparation method of industrialized carbonized steel slag and application thereof

Abstract

The present application relates to a kind of industrialized preparation method of carbonized steel slag and its application, and the preparation method includes the following steps: preparation of steel slag micro-powder, preparation of aerated block, carbonization aerated block, preparation of carbonized steel slag powder;Prepared carbonized steel slag powder is used to prepare SMA asphalt mixture.Adopt steel slag powder grinding into powder, steel slag powder preparation aerated block, carbonization, again the preparation process of grinding powder, can simultaneously realize large-scale, fast carbonized steel slag powder and the purpose of high carbon dioxide absorption amount, so as to realize low cost, industrialized large-scale production;Carbonized steel slag powder is added to asphalt instead of mineral powder, and the water stability of asphalt mixture is improved by 18%, which can achieve the purpose of safe, low-carbon, large-scale disposal of steel slag;Asphalt is flexible and oily, and there is no stability problem after the application of carbonized steel slag powder, which is safe and reliable.

Description

Technical Field

[0001] This invention relates to a method for carbonizing steel slag, and more particularly to a method for preparing carbon-negative, low-cost, safe, and efficient steel slag with high carbon absorption rate suitable for large-scale industrial production, as well as its application. Background Technology

[0002] Currently, my country produces hundreds of millions of tons of steel slag annually, yet effective disposal remains a challenge. Furthermore, the steel industry generates substantial carbon emissions, making carbon reduction an urgent necessity. Steel slag has a high calcium content and high carbonization activity, making it possible to utilize carbon dioxide emissions from steel mills to carbonize steel slag powder.

[0003] However, most current steel slag powder carbonization utilization schemes involve mixing it into ceramsite or bricks to obtain high-strength ceramsite and bricks through carbonization. Due to the limited market capacity for ceramsite and bricks, this utilization scheme is difficult to handle the massive quantities of steel slag.

[0004] Professor Mo Liwu of Nanjing University of Technology used carbonized steel slag powder and mineral powder to grind them into a composite admixture. However, as is well known, steel slag powder loses its activity after complete carbonization. To ensure the activity of the carbonized steel slag powder, the carbon dioxide absorption rate is only 5.1%, which is very low. Therefore, this utilization method has the disadvantages of low carbon dioxide absorption rate and difficulty in process control.

[0005] Asphalt concrete contains a large amount of mineral powder, which is actually calcium carbonate powder. After carbonation, steel slag powder forms a dense layer of calcium carbonate on its surface, which can be used as a substitute for mineral powder.

[0006] In order to dispose of large quantities of steel slag and significantly reduce carbon dioxide emissions from steel plants, it is necessary to develop a carbon-negative, low-cost, safe, high-capacity steel slag disposal method suitable for large-scale industrial production. Summary of the Invention

[0007] The technical problem to be solved by the present invention is to provide an industrial method for preparing carburized steel slag and its application in order to overcome the shortcomings of the existing technology.

[0008] The technical solution adopted in this invention is: a method for preparing industrially produced carburized steel slag, comprising the following steps:

[0009] S1. Preparation of steel slag powder: Steel slag particles are ground into powder by a vertical mill to obtain steel slag powder with an average particle size of 6.75μm;

[0010] S2. Preparation of aerated blocks: The steel slag powder obtained in S1 is mixed with quicklime, hydrogen peroxide and water in a certain proportion to prepare aerated blocks.

[0011] S3, Carbonized Aerated Blocks: The steel slag aerated blocks prepared in S2 are cut into 100*1000*1000mm plates, placed in a carbonization kettle, and carbon dioxide flue gas is introduced for carbonization to obtain fully carbonized steel slag aerated blocks.

[0012] S4. Preparation of carbide steel slag powder: The carbide aerated blocks obtained in S3 are ground into carbide steel slag micro powder with an average particle size of 6.75μm and then reused.

[0013] Furthermore, in S1, the steel slag particles are obtained by treating waste generated from steelmaking in steel plants through a hot simmering process.

[0014] Furthermore, in S2, the aerated concrete block comprises the following parts by weight of raw materials:

[0015] 90.6 parts of steel slag powder

[0016] 10.0 parts quicklime

[0017] 0.4 parts hydrogen peroxide

[0018] 65 parts water.

[0019] Steel slag powder has a high calcium content and is easily carbonized to form calcium carbonate. Quicklime is mainly composed of calcium oxide, which, when mixed with water, will form calcium hydroxide and activate the steel slag powder, giving the aerated concrete blocks strength. In addition, the hydration product of quicklime, calcium hydroxide, is also easily carbonized to form calcium carbonate. Hydrogen peroxide has a large gas production under alkaline conditions, which can give the aerated concrete blocks a large number of pores, making it easier for carbon dioxide to enter the aerated concrete blocks and accelerate carbonization.

[0020] Furthermore, in S2, the dry bulk density of the aerated concrete block is 600~700 kg / m³. 3 The compressive strength is 2.0 MPa;

[0021] The quicklime mentioned is quicklime from the lime kiln of the steel plant; the water is tap water; the hydrogen peroxide is 31% hydrogen peroxide with a pH value of 3.5.

[0022] Furthermore, in S3, the carbon dioxide flue gas comes from the lime kiln of the steel plant, with a carbon dioxide concentration of 22.0±0.5% and a carbonization time of 12h;

[0023] The carbonized aerated concrete block has a carbon dioxide absorption rate of 18.2%. The aerated concrete block has loose pores, so the carbon dioxide absorption rate is very high.

[0024] The above-mentioned industrial application of carbonized steel slag is that the carbonized steel slag powder is used to prepare SMA asphalt mixture.

[0025] Furthermore, the SMA asphalt mixture comprises aggregates, asphalt, and fibers.

[0026] The mineral material comprises the following raw materials in parts by weight:

[0027] #1 coarse aggregate 48.0 parts

[0028] 26.0 parts of coarse aggregate #2

[0029] 16.0 parts fine aggregate

[0030] 0-6 parts of mineral powder

[0031] 4-10 parts of carbide steel slag powder;

[0032] The ratio of asphalt to mineral aggregate is 5.8:100;

[0033] The fiber content is 0.3% of the total mass of the SMA asphalt mixture.

[0034] Furthermore, the No. 1 coarse aggregate is basalt coarse aggregate with a density of 3.028 kg / m³. 3 The particle size is 9.5~13.2mm;

[0035] The No. 2 coarse aggregate is basalt coarse aggregate with a density of 3.032 kg / m³. 3 The particle size is 4.75~9.5mm;

[0036] The fine aggregate mentioned is basalt fine aggregate with a density of 2.776 kg / m³. 3 The particle size is 0~2.36mm;

[0037] The mineral powder is limestone mineral powder with a density of 2.705 kg / m³. 3 The particle size is less than 0.075 mm;

[0038] The asphalt mentioned is SBS modified 70# asphalt;

[0039] The fiber in question is lignin fiber.

[0040] To simultaneously achieve large-scale, rapid carbonization of steel slag powder and high carbon dioxide absorption, it is necessary to maximize the porosity between steel slag powder particles, which requires forming aerated concrete blocks. However, to achieve low-carbon, safe, and low-cost utilization of steel slag powder, the aerated concrete block form is not suitable. The strength of the aerated concrete blocks in this invention does not meet national standards. To meet the national standard requirement of greater than 3.5 MPa, a large amount of quicklime would need to be added, which is not cost-effective and would also increase carbon emissions. Therefore, the carbonized aerated concrete blocks are ground into powder and added to asphalt to replace calcium carbonate mineral powder as a filler in the preparation of SMA asphalt mixtures. Since asphalt is flexible and oily, there are no stability issues after the application of carbonized steel slag powder.

[0041] The present invention has the following advantages over the prior art:

[0042] The process of grinding steel slag powder into powder, preparing aerated blocks from steel slag powder, carbonizing, and then grinding again can simultaneously achieve large-scale, rapid carbonization of steel slag powder and high carbon dioxide absorption, thus enabling low-cost, large-scale industrial production. It is a carbon-negative, low-cost, high-carbon-absorption method suitable for large-scale industrial production of steel slag, with a carbon absorption rate of up to 15.6% for the carbonized steel slag powder.

[0043] Adding carbonized steel slag powder to asphalt instead of mineral powder improves the water stability of asphalt mixtures by 18%, achieving the goal of safe, low-carbon, and large-scale disposal of steel slag.

[0044] Asphalt is a flexible and oily substance, and there are no stability issues after the application of carbide steel slag powder, making it safe and reliable. Detailed Implementation

[0045] The embodiments of the present invention are described in detail below. The embodiments are implemented based on the technical solution of the present invention, and detailed implementation methods and specific operation processes are given. However, the protection scope of the present invention is not limited to the following embodiments.

[0046] A method for preparing industrially produced carburized steel slag includes the following steps:

[0047] S1. Preparation of steel slag powder: Steel slag particles are ground into powder by a vertical mill to obtain steel slag powder with an average particle size of 6.75μm;

[0048] S2. Preparation of aerated concrete blocks: The steel slag powder obtained in S1 is mixed with quicklime, hydrogen peroxide and water in a mass ratio of 90.6:10:0.4:65 to prepare aerated concrete blocks.

[0049] S3, Carbonized Aerated Blocks: The steel slag aerated blocks prepared in S2 are cut into 100*1000*1000mm plates, placed in a carbonization kettle, and carbonized with 22.0% carbon dioxide flue gas to obtain fully carbonized steel slag aerated blocks.

[0050] S4. Preparation of carbide steel slag powder: The carbide aerated blocks obtained in S3 are ground into carbide steel slag micro powder with an average particle size of 6.75μm and then reused.

[0051] Example 1

[0052] Steel slag powder is used to prepare SMA asphalt mixture. The SMA asphalt mixture includes aggregate, SBS modified 70# asphalt, and lignin fiber. The aggregate comprises the following raw materials by weight: 48.0 parts of #1 coarse aggregate, 26.0 parts of #2 coarse aggregate, 16.0 parts of fine aggregate, 6.0 parts of mineral powder, and 4.0 parts of steel slag powder. The ratio of asphalt to aggregate is 5.8%, and the lignin fiber accounts for 0.3% of the total mass of the SMA asphalt mixture. The above raw materials are mixed to obtain #1 asphalt mixture.

[0053] Example 2

[0054] The difference from Example 1 is that: 4.0 parts of mineral powder and 6.0 parts of carbonized steel slag powder were used to obtain Asphalt Mixture No. 2.

[0055] Example 3

[0056] The difference from Example 1 is that: 2.0 parts of mineral powder and 8.0 parts of carbonized steel slag powder were used to obtain Asphalt Mixture No. 3.

[0057] Example 4

[0058] The difference from Example 1 is that: 0 parts mineral powder and 10.0 parts carbonized steel slag powder were used. Asphalt mixture #4 was obtained.

[0059] Comparative Example 1

[0060] The difference from Example 1 is that: 10 parts mineral powder and 0 parts carbonized steel slag powder were used. This yielded #5 asphalt mixture.

[0061] Comparative Example 2

[0062] The difference from Example 4 is that 10.0 parts of uncarbonized steel slag powder were used. This yielded Asphalt Mixture #6.

[0063] Table 1. Performance of asphalt mixtures obtained from Examples 1-4 and Comparative Examples 1 and 2

[0064] Water-immersed Marshall / % Dynamic stability Small beam bent 1# 87.0% 11243 times / mm 3000με 2# 90.8% 12131 times / mm 3000με 3# 94.7% 13456 times / mm 3000με 4# 97.6% 14218 times / mm 3000με 5# 85.9% 10686 times / mm 3000με 6# 84.7% 10218 times / mm 3000με

[0065] As can be seen from the table above, it is obvious that the asphalt mixtures of Examples 1-4 exhibit significantly higher water stability (immersion Marshall stress) than Comparative Examples 1 and 2, up to 97.6% higher. Their high-temperature stability (dynamic stability) is also much higher than Comparative Examples 1 and 2, up to 14218 cycles / mm higher. Their low-temperature crack resistance (beam bending) is consistent with ordinary asphalt mixtures. The higher the content of carbonized steel slag powder, the better the water stability and high-temperature stability of the asphalt mixture.

[0066] From a cost perspective: the cost of grinding steel slag powder, preparing aerated blocks, and then grinding the raw materials and production costs is 70 yuan per ton, while the price of mineral powder in asphalt mixing plants is 200 yuan per ton. Replacing mineral powder with carbonized steel slag powder can not only greatly improve performance, but also create significant economic value. Furthermore, it consumes a large amount of difficult-to-process steel slag, achieving multiple benefits and having a broad market prospect.

[0067] As can be seen from the above data, the asphalt mixture carbonized steel slag powder prepared by this invention has a large carbon dioxide absorption capacity, can dispose of large quantities of difficult-to-treat solid waste, is low-carbon and environmentally friendly, has good physical and mechanical properties, high profit, and has extremely significant economic and social benefits.

Claims

1. An industrial application of carburized steel slag, characterized in that, The method for preparing industrially produced carburized steel slag includes the following steps: S1. Preparation of steel slag powder: Steel slag particles are ground into powder by a vertical mill to obtain steel slag powder with an average particle size of 6.75μm; S2. Preparation of aerated blocks: The steel slag powder obtained in S1 is mixed with quicklime, hydrogen peroxide and water in a certain proportion to prepare aerated blocks. S3, Carbonized Aerated Blocks: The aerated blocks prepared in S2 are cut into 100*1000*1000mm plates, placed in a carbonization kettle, and carbon dioxide flue gas is introduced for carbonization to obtain fully carbonized steel slag aerated blocks. S4. Preparation of carbide steel slag powder: The fully carbide steel slag aerated blocks obtained in S3 are ground into carbide steel slag micro powder with an average particle size of 6.75μm and then reused. In S1, the steel slag particles are obtained by hot quenching process from the waste generated by steelmaking in steel plants. In S2, the aerated block comprises the following raw materials in parts by weight: 90.6 parts of steel slag powder 10.0 parts quicklime 0.4 parts hydrogen peroxide 65 parts water; In S2, the dry density of the aerated concrete block is 600~700 kg / m³. 3 The compressive strength is 2.0 MPa; The quicklime mentioned is quicklime from the lime kiln of the steel plant; the water is tap water; the hydrogen peroxide is 31% hydrogen peroxide with a pH value of 3.5; In S3, the carbon dioxide flue gas comes from the lime kiln of the steel plant, with a carbon dioxide concentration of 22.0±0.5% and a carbonization time of 12h. The carbon dioxide absorption rate of the fully carbonized steel slag aerated block reaches 18.2%; The aforementioned carbide steel slag powder is used to prepare SMA asphalt mixture; The SMA asphalt mixture includes aggregates, asphalt, and fibers. The mineral material comprises the following raw materials in parts by weight: #1 coarse aggregate 48.0 parts 26.0 parts of coarse aggregate #2 16.0 parts fine aggregate 10 parts of carbide steel slag powder; The ratio of asphalt to mineral aggregate is 5.8:100; The fiber content is 0.3% of the total mass of the SMA asphalt mixture; The No. 1 coarse aggregate is basalt coarse aggregate with a density of 3.028 kg / m³. 3 The particle size is 9.5~13.2mm; The No. 2 coarse aggregate is basalt coarse aggregate with a density of 3.032 kg / m³. 3 The particle size is 4.75~9.5mm; The fine aggregate mentioned is basalt fine aggregate with a density of 2.776 kg / m³. 3 The particle size is 0~2.36mm; The asphalt mentioned is SBS modified 70# asphalt; The fiber in question is lignin fiber.