Steel slag and slag cement and preparation method thereof

Abstract

The invention discloses steel slag and slag cement and a preparation method thereof, and belongs to the technical field of cement environment-friendly material processing. The steel slag and slag cement provided by the invention comprises the following raw materials by weight: 45.00-55.00% of milled cement; the content of the composite powder is 10.00 to 20.00 percent; the content of the superfine powder is 35.00 to 45.00 percent; the invention also discloses a preparation method of the steel slag and slag cement. According to the steel slag and slag cement, the grinding process of each solid waste is reasonably planned, a respective grinding strategy is adopted, and superfine grinding is performed on part of composite powder, high-magnesium limestone, calcium chloride and refined steel slag with different fineness degrees, so that the micro porosity in set cement is effectively reduced, the compactness is remarkably increased, the wear resistance of concrete is remarkably improved, and the service life of the concrete is prolonged. The 28-day flexural and compressive strength of the prepared cement product is remarkably improved, the 28-day dry shrinkage rate and abrasion loss also meet the national detection standard of special cement (road Portland cement), and the cement water-soluble hexavalent chromium is not greater than 5 ppm at 40 DEG C.

Description

[Technical field]

[0001] The invention relates to the technical field of environmentally friendly materials, and in particular to steel slag slag cement and a preparation method thereof. [Background technology]

[0003] The main sources of carbon emissions from cement material production are: ① fossil fuel combustion, ② carbonate raw material decomposition, ③ raw material mining and preparation, and power consumption during the production process. The main technical approaches to reducing carbon emissions from cement materials are: fossil fuel substitution, carbonate raw material substitution, reducing the proportion of clinker burned, improving cement materials and project quality, etc., most of which are directly related to solid waste utilization. Solid waste is called "resources in the wrong place", and replacing natural raw materials and fuels with solid waste can directly reduce carbon emissions. The present invention aims to stimulate and utilize the inherent characteristics of solid waste, strengthen the good mutual stimulation between solid waste and clinker, increase the amount of solid waste added in the cement production process, optimize the various performance properties of cement, and produce cement suitable for road engineering construction to serve economic construction.

[0004] In November 2023, the GB175-2023 "General Portland Cement" standard was officially released. The technical indicators are closer to the European cement standard EN197-1, focusing on the dual-wheel drive of "increasing varieties and improving quality" and "greening, standardization, serialization, and traceability" to promote the sustainable and healthy development of my country's cement industry. The standard clearly stipulates that steel slag cannot be used as an admixture for general Portland cement, and the use of steel slag in the raw material end of cement production is plagued by water-soluble hexavalent chromium. Solving the problem of large-scale steel slag incorporation at the cement end is an urgent problem to be solved in the cement industry, and it is also a key issue that needs to be paid attention to in order to maintain the national ecological environment and sustainable economic development. [Summary of the invention]

[0005] The purpose of the present invention is to provide a steel slag slag cement and a preparation method thereof in view of the above-mentioned problems existing in the prior art. The present invention adopts separate grinding and ultrafine grinding processes, and the materials are ground one by one to a certain particle size and then mixed evenly to achieve the production of steel slag slag silicate cement.

[0006] To achieve the above purpose, the technical solution of the present invention is as follows:

[0007] A steel slag slag cement, the raw material composition and weight ratio of which are as follows:

[0008] Out-grinding cement: 45.00~55.00%;

[0009] Composite powder: 10.00~20.00%;

[0010] Ultrafine powder: 35.00~45.00%;

[0011] The composite powder is obtained by mixing granulated blast furnace slag powder and refined steel slag powder in a weight ratio of 75-80:20-25.

[0012] It is further explained that the mass coefficient K of the granulated blast furnace slag is ≥1.2, and the activity index is ≥95%; the activity index of the refined steel slag is 70% to 85%.

[0013] Further explanation: the specific surface area of ​​the composite powder is 500m 2 / kg, moisture ≤0.5%.

[0014] Further explanation: the surface area of ​​the ultrafine powder is 800m 2 / kg, moisture ≤0.2%.

[0015] It is further explained that the particle size of the ultrafine powder is 45 μm square hole sieve residue ≤ 8%.

[0016] It is further explained that the composition and / or certain properties of the refined steel slag are supplemented.

[0017] The present invention also provides a method for preparing steel slag slag cement, comprising the following steps:

[0018] S1. Preparation of cement out of mill

[0019] The silicate cement clinker and gypsum are fed into the cement mill in a weight ratio of 90-97:3-10 through the electronic metering system of the grinding head and ground to a specific surface area of ​​350m 2 / kg, 45um fineness is 11% to 12.0%;

[0020] S2. Preparation of composite powder

[0021] After pre-homogenization of granulated blast furnace slag and refined steel slag in the raw material yard, they are mixed in a mass ratio of granulated blast furnace slag: steel slag = 75-80:20-25 and then put into the roller mill for grinding. During the grinding process, the specific surface area of ​​the composite powder out of the mill is controlled to be 500m 2 / kg, moisture ≤0.5%, the composite powder enters the composite powder warehouse through the conveying system for standby;

[0022] S3. Preparation of ultrafine powder

[0023] (1) drying the refined steel slag in the sun, mixing it with the composite powder of step S2 in a certain proportion, and grinding it into powder A;

[0024] (2) Mix powder A, calcium chloride and high-magnesium limestone and grind them into powder B until the specific surface area is 800m 2 / kg, moisture ≤0.2%, transported to the ultrafine powder warehouse through the conveying system for standby;

[0025] S4. Cement preparation

[0026] The cement, superfine powder and composite powder are put into the homogenizing device according to the proportion and fully mixed, and then transported to the cement mill through the conveying system to make cement products.

[0027] Further, in step S2, the residue on the 45 μm square hole sieve of the composite powder is not more than 10%.

[0028] To further illustrate, in step S3, the ultrafine powder is a composite powder, refined steel slag, high-magnesium limestone and calcium chloride in a weight ratio of 60-70:10-20:30-40:0.05.

[0029] Compared with the prior art, the present invention has the following beneficial effects:

[0030] 1. The finished cement product prepared by the scheme of the present invention fully strengthens the benign effects of various materials and avoids adverse reactions. Granulated blast furnace slag powder and steel slag are compounded, and the volcanic ash effect, morphological effect and micro-aggregate effect of the two materials are superimposed on each other, so that the concrete has good fracture resistance and shrinkage resistance. The composite powder and high-magnesium limestone, calcium chloride and refined steel slag powders of different fineness are orderly combined to further reduce the internal microscopic porosity of the cement stone, significantly increase the density, and significantly improve the wear resistance of the concrete. The 28-day flexural and compressive strength of the cement product prepared by the present invention is effectively improved, the 28-day shrinkage rate is not more than 0.10%, and the 28-day abrasion loss is not more than 2.00kg / m 2 , 60d wear loss is not more than 3.00kg / m 2 , the water-soluble hexavalent chromium in cement shall not exceed 5ppm at 40℃.

[0031] 2. The present invention adopts a strategy of separate grinding by rationally planning the grinding process of each solid waste, and performs ultrafine grinding on some composite powders. Different processes are used in the two grinding stages, which not only increases the specific surface area of ​​the solid waste, but also optimizes the morphology of the material particles, and achieves a significant improvement in the early activity of the solid waste. High-magnesium limestone and calcium chloride are added during the ultrafine grinding process. These two additives not only solve the problem of material agglomeration, but also strengthen the positive interaction between granulated blast furnace slag and steel slag, further stimulating the early activity of the solid waste. At the same time, this method can also reduce the content of soluble hexavalent chromium in the product to a certain extent and improve the environmental performance of cement. The solid waste and clinker are ground separately, and the composite powder is ultrafinely ground with an appropriate amount of steel slag. This strategy enables each material to achieve the optimal specific surface area for activity, while optimizing the particle grading of cement. In addition, the method of separate grinding and ultrafine grinding also reduces the power consumption in the cement grinding process, reduces the emission of carbon dioxide, and achieves the goal of energy conservation and emission reduction.

[0032] In summary, the present invention has successfully improved the early activity of solid waste and solved the problem of limited solid waste addition in the traditional cement production process by rationally planning the solid waste grinding process, adding specific additives to solve the agglomeration problem, and optimizing cement particle grading and other innovative technologies. At the same time, this invention also reduces the energy consumption and emissions of cement production, providing strong support for the sustainable development of the cement industry. [Specific implementation method]

[0033] In order to make the above-mentioned purpose, features and advantages of the present invention more obvious and easy to understand, the specific implementation of the present invention is described in detail below. In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without violating the connotation of the present invention, so the present invention is not limited by the specific implementation disclosed below.

[0034] Example 1

[0035] A steel slag slag cement, the raw material composition and weight ratio of which are as follows: mill cement: 45.00%; composite powder: 10.00%; superfine powder: 45.00%;

[0036] The method for preparing steel slag slag cement comprises the following steps:

[0037] S1. Preparation of cement out of mill

[0038] The silicate cement clinker and gypsum are fed into the cement mill in a weight ratio of 90:3 through the electronic metering system of the grinding head and ground to a specific surface area of ​​350m 2 / kg, 45um fineness is 11%;

[0039] S2. Preparation of composite powder

[0040] After pre-homogenization of granulated blast furnace slag and refined steel slag in the raw material yard, they are mixed in a mass ratio of granulated blast furnace slag: steel slag = 75:20 and then put into the roller mill for grinding. During the grinding process, the specific surface area of ​​the composite powder out of the mill is controlled to be 500m 2 / kg, moisture ≤0.5%, 45μm square hole sieve residue is not more than 10%, the composite powder enters the composite powder warehouse through the conveying system for standby; the quality coefficient K of granulated blast furnace slag is ≥1.2, and the activity index is ≥95%; the activity index of the refined steel slag is 70%;

[0041] S3. Preparation of ultrafine powder

[0042] (1) drying the refined steel slag in the sun, mixing it with the composite powder of step S2 in a certain proportion, and grinding it into powder A;

[0043] (2) Mix powder A, calcium chloride and high-magnesium limestone and grind them into powder B until the specific surface area is 800m 2 / kg, moisture ≤0.2%, transported to the ultrafine powder warehouse through the conveying system for standby;

[0044] The weight ratio of composite powder, refined steel slag, high-magnesium limestone and calcium chloride is 60:10:30:0.05;

[0045] The activity index of the refined steel slag is 70%;

[0046] S4. Cement preparation

[0047] The cement, superfine powder and composite powder are put into the homogenizing device according to the proportion and fully mixed, and then transported to the cement mill through the conveying system to form cement products (No. 1).

[0048] Example 2

[0049] A steel slag slag cement, the raw material composition and weight ratio of which are as follows: mill cement: 55.00%; composite powder: 10.00%; ultrafine powder: 35.00%;

[0050] The method for preparing steel slag slag cement comprises the following steps:

[0051] S1. Preparation of cement out of mill

[0052] The silicate cement clinker and gypsum are fed into the cement mill in a weight ratio of 97:10 through the electronic metering system of the grinding head and ground to a specific surface area of ​​350m 2 / kg, 45um fineness is 12.0%;

[0053] S2. Preparation of composite powder

[0054] Granulated blast furnace slag and refined steel slag are pre-homogenized in the raw material yard, and then mixed in a mass ratio of granulated blast furnace slag: steel slag = 80:25 and then put into the roller mill for grinding. During the grinding process, the specific surface area of ​​the composite powder out of the mill is controlled to be 500m 2 / kg, moisture ≤0.5%, 45μm square hole sieve residue is not more than 10%, the composite powder enters the composite powder warehouse through the conveying system for standby; the quality coefficient K of granulated blast furnace slag is ≥1.2, and the activity index is ≥95%; the activity index of the refined steel slag is 75%;

[0055] S3. Preparation of ultrafine powder

[0056] (1) drying the refined steel slag in the sun, mixing it with the composite powder of step S2 in a certain proportion, and grinding it into powder A;

[0057] (2) Mix powder A, calcium chloride and high-magnesium limestone and grind them into powder B until the specific surface area is 800m 2 / kg, moisture ≤0.2%, transported to the ultrafine powder warehouse through the conveying system for standby;

[0058] The weight ratio of composite powder, refined steel slag, high-magnesium limestone and calcium chloride is 70:20:40:0.05;

[0059] The activity index of the refined steel slag is 75%;

[0060] S4. Cement preparation

[0061] The cement, superfine powder and composite powder are put into the homogenizing device according to the proportion and fully mixed, and then transported to the cement mill through the conveying system to form cement products (No. 2).

[0062] Example 3

[0063] A steel slag slag cement, the raw material composition and weight ratio of which are as follows: mill cement: 45.00%; composite powder: 20.00%; ultrafine powder: 35.00%;

[0064] The method for preparing steel slag slag cement comprises the following steps:

[0065] S1. Preparation of cement out of mill

[0066] The silicate cement clinker and gypsum are fed into the cement mill in a weight ratio of 95:5 through the electronic metering system of the grinding head and ground to a specific surface area of ​​350m 2 / kg, 45um fineness is 11%;

[0067] S2. Preparation of composite powder

[0068] Granulated blast furnace slag and refined steel slag are pre-homogenized in the raw material yard, and then mixed in a mass ratio of granulated blast furnace slag: steel slag = 75:25 and then put into the roller mill for grinding. During the grinding process, the specific surface area of ​​the composite powder out of the mill is controlled to be 500m 2 / kg, moisture ≤0.5%, 45μm square hole sieve residue is not more than 10%, the composite powder enters the composite powder warehouse through the conveying system for standby; the quality coefficient K of granulated blast furnace slag is ≥1.2, and the activity index is ≥95%; the activity index of the refined steel slag is 80%;

[0069] S3. Preparation of ultrafine powder

[0070] (1) drying the refined steel slag in the sun, mixing it with the composite powder of step S2 in a certain proportion, and grinding it into powder A;

[0071] (2) Mix powder A, calcium chloride and high-magnesium limestone and grind them into powder B until the specific surface area is 800m 2 / kg, moisture ≤0.2%, transported to the ultrafine powder warehouse through the conveying system for standby;

[0072] The weight ratio of composite powder, refined steel slag, high-magnesium limestone and calcium chloride is 65:15:35:0.05;

[0073] The activity index of the refined steel slag is 80%;

[0074] S4. Cement preparation

[0075] The cement, superfine powder and composite powder are put into the homogenizing device according to the proportion and fully mixed, and then transported to the cement mill through the conveying system to form cement products (No. 3).

[0076] Example 4

[0077] A steel slag slag cement, the raw material composition and weight ratio of which are as follows: 50.00% of mill cement; 15.00% of composite powder; 35.00% of ultrafine powder;

[0078] The method for preparing steel slag slag cement comprises the following steps:

[0079] S1. Preparation of cement out of mill

[0080] The silicate cement clinker and gypsum are fed into the cement mill in a weight ratio of 90:10 through the electronic metering system of the grinding head and ground to a specific surface area of ​​350m 2 / kg, 45um fineness is 11%;

[0081] S2. Preparation of composite powder

[0082] After pre-homogenization of granulated blast furnace slag and refined steel slag in the raw material yard, they are mixed in a mass ratio of granulated blast furnace slag: steel slag = 80:20 and then put into the roller mill for grinding. During the grinding process, the specific surface area of ​​the composite powder out of the mill is controlled to be 500m 2 / kg, moisture ≤0.5%, 45μm square hole sieve residue is not more than 10%, the composite powder enters the composite powder warehouse through the conveying system for standby; the quality coefficient K of granulated blast furnace slag is ≥1.2, and the activity index is ≥95%; the activity index of the refined steel slag is 85%;

[0083] S3. Preparation of ultrafine powder

[0084] (1) drying the refined steel slag in the sun, mixing it with the composite powder of step S2 in a certain proportion, and grinding it into powder A;

[0085] (2) Mix powder A, calcium chloride and high-magnesium limestone and grind them into powder B until the specific surface area is 800m 2 / kg, moisture ≤0.2%, transported to the ultrafine powder warehouse through the conveying system for standby;

[0086] The weight ratio of composite powder, refined steel slag, high-magnesium limestone and calcium chloride is 60:20:40:0.05;

[0087] The activity index of the refined steel slag is 85%;

[0088] S4. Cement preparation

[0089] The cement, superfine powder and composite powder are put into the homogenizing device according to the proportion and fully mixed, and then transported to the cement mill through the conveying system to form cement products (No. 4).

[0090] Example 5

[0091] A steel slag slag cement, the raw material composition and weight ratio of which are as follows: mill cement: 45.00%; composite powder: 15.00%; superfine powder: 40.00%;

[0092] The method for preparing steel slag slag cement comprises the following steps:

[0093] S1. Preparation of cement out of mill

[0094] The silicate cement clinker and gypsum are fed into the cement mill in a weight ratio of 90:10 through the electronic metering system of the grinding head and ground to a specific surface area of ​​350m 2 / kg, 45um fineness is 12.0%;

[0095] S2. Preparation of composite powder

[0096] After pre-homogenization of granulated blast furnace slag and refined steel slag in the raw material yard, they are mixed in a mass ratio of granulated blast furnace slag: steel slag = 80:20 and then put into the roller mill for grinding. During the grinding process, the specific surface area of ​​the composite powder out of the mill is controlled to be 500m 2 / kg, moisture ≤0.5%, 45μm square hole sieve residue is not more than 10%, the composite powder enters the composite powder warehouse through the conveying system for standby; the quality coefficient K of granulated blast furnace slag is ≥1.2, and the activity index is ≥95%; the activity index of the refined steel slag is 85%;

[0097] S3. Preparation of ultrafine powder

[0098] (1) drying the refined steel slag in the sun, mixing it with the composite powder of step S2 in a certain proportion, and grinding it into powder A;

[0099] (2) Mix powder A, calcium chloride and high-magnesium limestone and grind them into powder B until the specific surface area is 800m 2 / kg, moisture ≤0.2%, transported to the ultrafine powder warehouse through the conveying system for standby;

[0100] The weight ratio of composite powder, refined steel slag, high-magnesium limestone and calcium chloride is 70:10:30:0.05;

[0101] The activity index of the refined steel slag is 85%;

[0102] S4. Cement preparation

[0103] The cement, superfine powder and composite powder discharged from the mill are fed into a homogenizing device according to a certain proportion and fully mixed, and then transported to the cement mill through a conveying system to form cement products (No. 5).

[0104] Example 6

[0105] A steel slag slag cement, whose raw material composition and weight ratio are the same as those in specific embodiment 5.

[0106] The preparation method of steel slag slag cement is basically the same as that of Example 5, except that the ratio of raw materials in the ultrafine powder is: composite powder, refined steel slag, high magnesium limestone and calcium chloride in a weight ratio of 65:15:35:0.05; the prepared cement product (No. 6) is obtained.

[0107] Example 7

[0108] A steel slag slag cement, whose raw material composition and weight ratio are the same as those in specific embodiment 5.

[0109] The preparation method of steel slag slag cement is basically the same as that of Example 5, except that:

[0110] S3. Preparation of ultrafine powder

[0111] After the refined steel slag is dried, it is first mixed with the composite powder of step S2 in a certain proportion and ground into powder A until the specific surface area is 800m 2 / kg, moisture ≤0.2%, transported to the ultrafine powder warehouse through the conveying system for standby; the weight ratio of the composite powder and the refined steel slag is 70:10; the activity index of the refined steel slag is 85%; the prepared cement product (No. 7).

[0112] Example 8

[0113] A steel slag slag cement, whose raw material composition and weight ratio are the same as those in specific embodiment 5.

[0114] The preparation method of steel slag slag cement is basically the same as that of Example 5, except that:

[0115] S3. Preparation of ultrafine powder

[0116] (1) drying the refined steel slag in the sun, mixing it with the composite powder of step S2 in a certain proportion, and grinding it into powder A;

[0117] (2) Mix powder A and high-magnesium limestone and grind them into powder B until the specific surface area is 800m 2 / kg, moisture ≤0.2%, transported to the ultrafine powder warehouse through the conveying system for standby;

[0118] The weight ratio of composite powder, refined steel slag and high-magnesium limestone is 70:10:30; the prepared cement product (No. 8) is obtained.

[0119] Example 9

[0120] A steel slag slag cement, whose raw material composition and weight ratio are the same as those in specific embodiment 5.

[0121] The preparation method of steel slag slag cement is basically the same as that of Example 5, except that:

[0122] S3. Preparation of ultrafine powder

[0123] (1) drying the refined steel slag in the sun, mixing it with the composite powder of step S2 in a certain proportion, and grinding it into powder A;

[0124] (2) Mix powder A and high-magnesium limestone and grind them into powder B until the specific surface area is 800m 2 / kg, moisture ≤0.2%, transported to the ultrafine powder warehouse through the conveying system for standby;

[0125] The weight ratio of composite powder, refined steel slag and high-magnesium limestone is 70:10:25; the prepared cement product (No. 9) is obtained.

[0126] Example 10

[0127] A steel slag slag cement, whose raw material composition and weight ratio are the same as those in specific embodiment 5.

[0128] The preparation method of steel slag slag cement is basically the same as that of Example 5, except that:

[0129] S3. Preparation of ultrafine powder

[0130] (1) drying the refined steel slag in the sun, mixing it with the composite powder of step S2 in a certain proportion, and grinding it into powder A;

[0131] (2) Mix powder A and high-magnesium limestone and grind them into powder B until the specific surface area is 800m 2 / kg, moisture ≤0.2%, transported to the ultrafine powder warehouse through the conveying system for standby;

[0132] The weight ratio of composite powder, refined steel slag and high-magnesium limestone is 70:10:45; the prepared cement product (No. 10) is obtained.

[0133] Embodiment 11

[0134] A steel slag slag cement, whose raw material composition and weight ratio are the same as those in specific embodiment 5.

[0135] The preparation method of steel slag slag cement is basically the same as that of Example 5, except that:

[0136] S3. Preparation of ultrafine powder

[0137] (1) drying the refined steel slag in the sun, mixing it with the composite powder of step S2 in a certain proportion, and grinding it into powder A;

[0138] (2) Mix powder A and calcium chloride and grind them into powder B until the specific surface area is 800m 2 / kg, moisture ≤0.2%, transported to the ultrafine powder warehouse through the conveying system for standby;

[0139] The weight ratio of composite powder, refined steel slag and calcium chloride is 70:10:0.1; the prepared cement product (No. 11) is obtained.

[0140] Example 12

[0141] A steel slag slag cement, whose raw material composition and weight ratio are the same as those in specific embodiment 5.

[0142] The preparation method of steel slag slag cement is basically the same as that of Example 5, except that:

[0143] S3. Preparation of ultrafine powder

[0144] (1) drying the refined steel slag in the sun, mixing it with the composite powder of step S2 in a certain proportion, and grinding it into powder A;

[0145] (2) Mix powder A, calcium chloride and high-magnesium limestone and grind them into powder B until the specific surface area is 800m 2 / kg, moisture ≤0.2%, transported to the ultrafine powder warehouse through the conveying system for standby;

[0146] The weight ratio of composite powder, refined steel slag, high-magnesium limestone and calcium chloride is 70:10:30:0.1; the prepared cement product (No. 12) is obtained.

[0147] Embodiment 13

[0148] A steel slag slag cement, the raw material composition and weight ratio of which are as follows: mill cement: 45.00%; composite powder: 55.00%;

[0149] The method for preparing steel slag slag cement comprises the following steps:

[0150] S1. Preparation of cement out of mill

[0151] The silicate cement clinker and gypsum are fed into the cement mill in a weight ratio of 90:10 through the electronic metering system of the grinding head and ground to a specific surface area of ​​350m 2 / kg, 45um fineness is 12.0%;

[0152] S2. Preparation of composite powder

[0153] After pre-homogenization of granulated blast furnace slag and refined steel slag in the raw material yard, they are mixed in a mass ratio of granulated blast furnace slag: steel slag = 80:20 and then put into the roller mill for grinding. During the grinding process, the specific surface area of ​​the composite powder out of the mill is controlled to be 500m 2 / kg, moisture ≤0.5%, 45μm square hole sieve residue is not more than 10%, the composite powder enters the composite powder warehouse through the conveying system for standby; the quality coefficient K of granulated blast furnace slag is ≥1.2, and the activity index is ≥95%; the activity index of the refined steel slag is 85%;

[0154] S3. Cement preparation

[0155] The cement and composite powder discharged from the mill are fed into a homogenizing device according to a certain proportion and fully mixed, and then transported to the cement mill through a conveying system to form cement products (No. 13).

[0156] Refer to GB / T17671 "Test Method for Strength of Cement Mortar (ISO Method)" to test the 3d and 28d strength of each group of cement in Table 1. Refer to the national standard GB31893-2015 "Limits and Determination Methods of Water-soluble Hexavalent Chromium (VI) in Cement" to test the water-soluble hexavalent chromium dissolution concentration (40℃, ppm) of each group of cement in Table 1. Refer to the national standard GBT13693-2017 for road silicate cement to test the shrinkage rate and wear resistance of each group of cement in Table 1.

[0157] Table 1 Cement test results

[0158]

[0159] From the above table, it can be seen that the 3-day flexural strength of cement products using the technical solutions of the present invention (No. 1-No. 6) is not less than 6.3MPa, and the compressive strength is not less than 19.76MPa; the 28-day flexural strength is not less than 8.54MPa, and the compressive strength is not less than 47MPa; the 28-day shrinkage is less than 0.1%, between 0.04-0.05%; the 28-day abrasion loss is not higher than 1.7kg / m 2 、60-day wear loss is not higher than 2.05kg / m 2 At 40℃ and 6d, the water-soluble hexavalent chromium content of cement was below 5mg / Kg. As time went on, there was almost no large amount of water-soluble hexavalent chromium that continued to dissolve, and the stability was obviously very good.

[0160] For No. 7, when preparing ultrafine powder, high-magnesium limestone and calcium chloride were not used for grinding together, and the flexural and compressive strengths were reduced, and the reduction was greater than that of No. 8. No. 8 did not add calcium chloride only when preparing ultrafine powder, indicating that high-magnesium limestone and calcium chloride can improve grinding to a certain extent. The agglomeration problem affects the positive interaction between ultrafine powder and composite powder, stimulates early activity, and thus enhances the flexural and compressive capacity of cement. And from the data recorded in the table, as time goes by, the water-soluble hexavalent chromium content of the cement of this application no longer increases, and the increase is much smaller than that of No. 7-13. Not adding high-magnesium limestone and calcium chloride at the same time did not achieve the effect of synergistically reducing chromium.

[0161] Looking at the data of No. 9-10, it can be concluded that when preparing ultrafine powder, excessive or too low addition of high-magnesium limestone will have a counterproductive effect. When the amount is excessive, the flexural and compressive strengths will decrease by 2.5MPa and 3MPa respectively after 3 days; the flexural strength will decrease by 1.86MPa and 2.9MPa after 28 days; when the amount added is too low, the flexural and compressive strengths will decrease by 2.2MPa and 2.9MPa respectively after 3 days; the flexural strength will decrease by 1.64MPa and 2.5MPa after 28 days. When the amount added is excessive, the 28d shrinkage index increases by 0.05%, and the 28d abrasion increases by 0.97kg / m 2 , 60d wear loss increased by 0.93kg / m 2 When the addition amount is too low, the 28d shrinkage index increases by 0.041%, and the 28d abrasion loss increases by 0.87kg / m 2 , 60d wear loss increased by 0.93kg / m 2 .

[0162] For No. 11-12, when only excessive calcium chloride was added without high-magnesium limestone, the indicators were worse than those when high-magnesium limestone was added without calcium chloride. It is obvious that these two solutions are obviously not conducive to the early strength of cement. They also do not have a good stabilizing effect on the later wear. It can be seen that excessive addition of calcium chloride reduces the strength of cement and increases the wear of cement.

[0163] From No. 13, we can see that the flexural and compressive strengths of cement obtained without adding ultrafine powder do not meet the indicators of standard cement, and the abrasion amount is also far beyond the specified indicators.

[0164] From the indicator of the dissolution concentration of water-soluble hexavalent chromium in cement, the technical solution of the present application basically maintains stability after 6 to 12 days, while the cement prepared without the technical solution of the present application has a trend of continuing to increase and dissolution amount.

[0165] In summary, the raw material composition and weight ratio of the present application are as follows: 45.00-55.00% of the cement produced by grinding; 10.00-20.00% of the composite powder; and 35.00-45.00% of the ultrafine powder. The composite powder is obtained by mixing granulated blast furnace slag powder and refined steel slag powder in a weight ratio of 75-80:20-25. The ultrafine powder is obtained by mixing and grinding composite powder, refined steel slag, high magnesium limestone and calcium chloride in a weight ratio of 60-70:10-20:30-40:0.05. The water-soluble hexavalent chromium dissolution concentration of the prepared steel slag slag cement remains basically stable after 12 days. The strength is greatly improved, which is particularly beneficial to the early strength of the cement.

[0166] The above descriptions of all equivalent changes or modifications accomplished under the technical spirit suggested by the present invention should be included in the present invention. They are detailed descriptions of the preferred embodiments of the present invention, but the embodiments are not intended to limit the scope of the patent application of the present invention, but cover the scope of the patent.

Claims

1. A steel slag slag cement, characterized in that: The raw material composition and weight ratio are as follows: Out-grinding cement: 45.00~55.00%; Composite powder: 10.00~20.00%; Ultrafine powder: 35.00~45.00%; The composite powder is obtained by mixing granulated blast furnace slag powder and refined steel slag powder in a weight ratio of 75-80:20-25.

2. The steel slag slag cement according to claim 1, characterized in that: The mass coefficient K of the granulated blast furnace slag is ≥1.2, and the activity index is ≥95%; the activity index of the refined steel slag is 70% to 85%.

3. The steel slag slag cement according to claim 1, characterized in that: The specific surface area of ​​the composite powder is 500m 2 / kg, moisture ≤0.5%.

4. The steel slag slag cement according to claim 1, characterized in that: The surface area of ​​the ultrafine powder is 800m 2 / kg, moisture ≤0.2%.

5. The steel slag slag cement according to claim 1, characterized in that: The particle size of the ultrafine powder is 45 μm square hole sieve residue ≤ 8%.

6. The steel slag slag cement according to claim 1, characterized in that: The composition and / or certain properties of the refined steel slag are supplemented.

7. The method for preparing steel slag slag cement according to claim 1, characterized in that: The following steps are involved: S1. Preparation of cement out of mill The silicate cement clinker and gypsum are fed into the cement mill in a weight ratio of 90-97:3-10 through the electronic metering system of the grinding head and ground to a specific surface area of ​​350m 2 / kg, 45um fineness is 11% to 12.0%; S2. Preparation of composite powder After pre-homogenization of granulated blast furnace slag and refined steel slag in the raw material yard, they are mixed in a mass ratio of granulated blast furnace slag: steel slag = 75-80:20-25 and then put into the roller mill for grinding. During the grinding process, the specific surface area of ​​the composite powder out of the mill is controlled to be 500m 2 / kg, moisture ≤0.5%, the composite powder enters the composite powder warehouse through the conveying system for standby; S3. Preparation of ultrafine powder (1) drying the refined steel slag in the sun, mixing it with the composite powder of step S2 in a certain proportion, and grinding it into powder A; (2) Mix powder A, calcium chloride and high-magnesium limestone and grind them into powder B until the specific surface area is 800m 2 / kg, moisture ≤0.2%, transported to the ultrafine powder warehouse through the conveying system for standby; S4. Cement preparation The cement, superfine powder and composite powder are put into the homogenizing device according to the proportion and fully mixed, and then transported to the cement mill through the conveying system to make cement products.

8. The preparation method according to claim 7, characterized in that: In step S2, the residue of the composite powder on a 45 μm square mesh sieve is no more than 10%.

9. The preparation method according to claim 7, characterized in that: In step S3, the ultrafine powder is a composite powder, refined steel slag, high-magnesium limestone and calcium chloride in a weight ratio of 60-70:10-20:30-40:0.05.

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