Low-cost unfired fast-hardening steel slag cement and preparation method thereof

Abstract

The invention discloses low-cost unfired quick-hardening steel slag cement and a preparation method thereof, and belongs to the technical field of effective utilization of waste resources. The method specifically comprises the following steps: (1) crushing and screening steel slag powder; (2) homogenizing and mixing the undersize steel slag powder, gypsum and limestone; (3) grinding the homogenized and mixed material to obtain a steel slag mixed powder grinding material; (4) screening the refining slag; (5) performing magnetic separation on the oversize material; (6) washing, airing, crushing and screening magnetic separation residues; (7) the undersize refining slag obtained in the step (6) is ground, and a refining slag powder grinding material is obtained; (8) homogenizing and mixing the refining slag powder grinding material and the steel slag mixed powder grinding material to obtain a mixed material; and (9) homogenizing and mixing the cement clinker powder grinding material and the mixed powder grinding material to obtain the cement. The blocky refining slag is used for partially replacing cement clinker to prepare the steel slag rapid hardening cement, and the unfired steel slag cement which is low in cost and high in early strength can be prepared.

Description

Technical Field

[0001] The invention belongs to the technical field of effective utilization of waste resources, and specifically relates to a low-cost, non-burning, fast-hardening steel slag cement and a preparation method thereof. Background Art

[0002] Ordinary slag cement is made of steel slag, Portland cement clinker, and an appropriate amount of gypsum. As a mixture of Portland cement, steel slag can improve the strength and durability of concrete while reducing the amount of cement used. For example, the compressive strength, flexural strength, and durability of steel slag concrete are better than those of ordinary concrete. The calcium silicate in steel slag mainly exists in the form of dicalcium silicate, with only a small amount of tricalcium silicate. The proportion of tricalcium silicate determines the early strength of cement, resulting in low early strength of the produced cement. The low early strength of slag cement limits its application in certain projects that require rapid hardening. Summary of the invention

[0003] In view of the above-mentioned prior art, the present invention provides a low-cost, non-burning, fast-hardening steel slag cement and a preparation method thereof, which solves the problem of insufficient early strength of ordinary steel slag cement in the prior art.

[0004] In order to achieve the above object, the technical solution adopted by the present invention is: to provide a method for preparing low-cost unburned rapid-hardening steel slag cement, comprising the following steps:

[0005] (1) crushing the steel slag powder, and then screening it with a 3 mm × 3 mm sieve to obtain the sieved steel slag powder and the sieved steel slag powder; the sieved steel slag powder is recycled;

[0006] (2) mixing the sieved steel slag powder, gypsum and limestone in a mass ratio of 20-40:4-6:4-6;

[0007] (3) Grind the homogenized and mixed materials to a specific surface area of ​​450-550m 2 / kg, to obtain steel slag mixed powder abrasive;

[0008] (4) Screening the refined slag using a 15 mm × 15 mm sieve to obtain the material above the sieve and the material below the sieve;

[0009] (5) subjecting the material on the screen to magnetic separation to separate the iron-containing material and the magnetic separation residue;

[0010] (6) washing the residue from magnetic separation, drying it until the moisture content is less than 5%; crushing it, and then screening it with a 3 mm × 3 mm sieve to obtain the sieve-surface refined slag and the sieve-under refined slag; the sieve-surface refined slag is reused;

[0011] (7) Grind the refined slag under the sieve to a specific surface area of ​​350-450m 2 / kg, refined slag powder abrasive is obtained;

[0012] (8) homogenizing and mixing the refined slag powder abrasive and the steel slag mixed powder abrasive in a mass ratio of 1 to 10:40 to obtain a mixed material;

[0013] (9) The cement clinker powder and the mixed powder are homogenously mixed in a mass ratio of 50-60:40-50 to obtain the product.

[0014] Based on the above technical solution, the present invention can also be improved as follows.

[0015] Furthermore, the method for recycling the steel slag powder on the screen is as follows: the steel slag powder on the screen is subjected to magnetic separation to separate the iron-containing material of the steel slag powder and the steel slag powder magnetic separation residue, and the steel slag powder magnetic separation residue is returned to the crushing equipment to be crushed together with the steel slag powder in step (1); the method for recycling the refined slag on the screen is as follows: the refined slag on the screen is subjected to magnetic separation to separate the iron-containing material of the refined slag and the refined slag magnetic separation residue; the refined slag magnetic separation residue is returned to the crushing equipment to be crushed together with the magnetic separation residue rinsed and dried in step (6).

[0016] Furthermore, the magnetic field strength for magnetic separation of the oversize slag powder and the oversize refined slag is 2500 to 3000 Gauss.

[0017] Furthermore, the equipment for crushing in step (1) and step (6) is a double roll crusher, a rod mill or a roller mill, the equipment for grinding in step (3) and step (7) is a roller mill or a ring roller mill, and the magnetic field strength for magnetic separation in step (5) is 1800 to 2000 Gauss.

[0018] Furthermore, the mass ratio of the mixed sifted steel slag powder, gypsum and limestone is 30:5:5.

[0019] Further, in step (3), the powder is ground to a specific surface area of ​​500 m 2 / kg; in step (7), the powder is ground to a specific surface area of ​​400m 2 / kg.

[0020] Furthermore, the magnetic separation residue is rinsed and then air-dried to a moisture content of 3.7%.

[0021] Furthermore, the mass ratio of the refined slag powder abrasive to the steel slag mixed powder abrasive is 5:40.

[0022] Furthermore, the specific surface area of ​​cement clinker powder is 400m 2 / kg, the mass ratio of cement clinker and mixed grinding materials is 50:50.

[0023] Furthermore, the above preparation method produces low-cost, unburned, fast-hardening steel slag cement.

[0024] The beneficial effects of the present invention are as follows: both steel slag powder and refined slag are derived from industrial waste and are rich in silicon, calcium, aluminum and other elements, which can form hydrated calcium silicate, hydrated calcium aluminate and other hydration products during cement hydration, thereby improving the strength of cement. At the same time, refined slag can further promote the hydration reaction of steel slag powder, form a denser microstructure, and enhance the hardness and durability of cement.

[0025] Refined slag is an alkaline slag rich in Al2O3 and CaO. The performance of its block and powder is quite different. The block part mainly exists in the form of Ca(AlO2)2. The addition of Ca(AlO2)2 can enhance the early strength of cement; while the powder part is mainly inactive dicalcium silicate. Therefore, separating the block and powder of refined slag can effectively retain the effective components of the block material and better retain the rapid hardening property of the obtained slag cement. The low proportion of tricalcium silicate in slag leads to low early strength, and only dicalcium silicate is a limited active gelling component. The refined slag powder obtained by grinding the block part can maximize the effective utilization of the effective component Ca(AlO2)2 of the refined slag, which can effectively improve the early strength of the slag cement. At the same time, the inactive refined slag powder is removed during the preparation process, so that the slag cement can maintain good rapid hardening property.

[0026] The mass ratio of the sieved steel slag powder, gypsum and limestone is 20-40:4-6:4-6, which can not only ensure the strength requirements of cement, but also maximize the use of industrial waste and reduce costs. At the same time, the mass ratio of refined slag powder abrasive and steel slag mixed powder abrasive is 0-10:40, so that the effective components in the refined slag can be fully utilized while maintaining the stability of cement. In addition, the ground cement clinker and the mixed material are homogenized and mixed at a mass ratio of 50-60:40-50, which not only ensures the strength and durability of cement, but also reduces the dependence on cement clinker and further reduces costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is the process flow chart of steel slag powder grinding;

[0028] Figure 2 This is the process flow chart of refined slag grinding;

[0029] Figure 3 This is the process flow chart for preparing low-cost, non-burning, fast-hardening steel slag cement. DETAILED DESCRIPTION

[0030] The specific implementation modes of the present invention are described in detail below with reference to the embodiments.

[0031] Example 1

[0032] A low-cost, unburned, fast-hardening steel slag cement, the preparation steps are as follows:

[0033] (1) The steel slag powder is crushed by using No. 1 crushing equipment (roller mill), and after crushing, it is screened by using a 3mm×3mm screen to obtain the steel slag powder on the screen and the steel slag powder under the screen; the steel slag powder is the 10mm under-screen tailings produced after the liquid steel slag is heated and stuffed according to the steel slag production process;

[0034] (2) The slag powder on the screen is magnetically separated by a No. 1 magnetic separation device (a magnetic separator with a magnetic field strength of 2600 Gauss) to separate the iron-containing materials of the slag powder and the magnetic separation residue of the slag powder. The iron-containing materials of the slag powder are discarded, and the magnetic separation residue of the slag powder is returned to the No. 1 crushing device for cyclic crushing;

[0035] (3) Mix the sieved steel slag powder, gypsum and limestone in a mass ratio of 30:5:5;

[0036] (4) Grind the homogenized and mixed materials to 500 mm in 1# grinding equipment (roller mill). 2 / kg, to obtain steel slag mixed powder abrasive;

[0037] (5) After the refined slag is naturally cooled, it is screened using a 15 mm × 15 mm sieve to obtain the material above the sieve and the material below the sieve;

[0038] (6) The material on the screen is magnetically separated by a 2# magnetic separation device (a magnetic separator with a magnetic field strength of 1800 Gauss) to separate the iron-containing material and the magnetic separation residue, and the iron-containing material is discarded;

[0039] (7) washing the residue from magnetic separation to remove the powdery material adhering to the surface, and then transferring it to a ventilated environment and drying it to a moisture content of 3.7%;

[0040] (8) The dried magnetic separation residue is crushed by a No. 2 crushing device (roller mill), and after crushing, it is sieved using a 3 mm × 3 mm sieve to obtain the sieve-surface refined slag and the sieve-under refined slag;

[0041] (9) The refined slag on the screen is subjected to magnetic separation by a 3# magnetic separation device (a magnetic separator with a magnetic field strength of 2600 Gauss) to separate the iron-containing materials in the refined slag and the magnetic separation residue of the refined slag; the iron-containing materials in the refined slag are discarded, and the magnetic separation residue of the refined slag is returned to the 2# crushing device for cyclic crushing;

[0042] (10) Grind the slag under the sieve to 400 m 2 / kg, refined slag powder abrasive is obtained;

[0043] (11) homogenizing and mixing the refined slag powder abrasive and the steel slag mixed powder abrasive in a mass ratio of 5:40 to obtain a mixed material;

[0044] (12) The specific surface area is 400m2 / kg cement clinker powder and the mixed material obtained in step (11) are homogenized and mixed in a mass ratio of 50:50 to obtain low-cost, non-burning, rapid-hardening steel slag cement.

[0045] The low-cost, unburned, fast-hardening steel slag cement of Examples 2 and 3 was prepared according to the method of Example 1. The amount of each material used and the properties of the prepared cement are shown in Table 1.

[0046] Comparative Example 1

[0047] A steel slag cement, the preparation steps are as follows:

[0048] (1) The steel slag powder is crushed by using No. 1 crushing equipment (roller mill), and after crushing, it is screened by using a 3mm×3mm screen to obtain the steel slag powder on the screen and the steel slag powder under the screen; the steel slag powder is the 10mm under-screen tailings produced after the liquid steel slag is heated and stuffed according to the steel slag production process;

[0049] (2) The slag powder on the screen is magnetically separated by a No. 1 magnetic separation device (a magnetic separator with a magnetic field strength of 2600 Gauss) to separate the iron-containing materials of the slag powder and the magnetic separation residue of the slag powder. The iron-containing materials of the slag powder are discarded, and the magnetic separation residue of the slag powder is returned to the No. 1 crushing device for cyclic crushing;

[0050] (3) Mix the sieved steel slag powder, gypsum and limestone in a mass ratio of 30:5:5;

[0051] (4) Grind the homogenized and mixed materials to 500 mm in 1# grinding equipment (roller mill). 2 / kg, to obtain steel slag mixed powder abrasive;

[0052] (5) After the refined slag is naturally cooled, it is screened using a 15 mm × 15 mm sieve to obtain the material above the sieve and the material below the sieve;

[0053] (6) The undersize material is magnetically separated by 2# magnetic separation equipment (magnetic separator with a magnetic field strength of 1800 Gauss) to separate the iron-containing material and the magnetic separation residue, and the iron-containing material is discarded;

[0054] (7) The residue from magnetic separation is crushed by using No. 2 crushing equipment (roller mill), and after crushing, it is screened by using a 3 mm × 3 mm screen to obtain the refined slag above the screen and the refined slag below the screen;

[0055] (8) The refined slag on the screen is subjected to magnetic separation by a 3# magnetic separation device (a magnetic separator with a magnetic field strength of 2600 Gauss) to separate the iron-containing material from the refined slag and the magnetic separation residue from the refined slag; the iron-containing material from the refined slag is discarded, and the magnetic separation residue from the refined slag is returned to the 2# crushing device for cyclic crushing;

[0056] (9) Grind the slag under the sieve to 400 m3 / s by 2# grinding equipment (roller mill). 2 / kg, refined slag powder abrasive is obtained;

[0057] (10) homogenizing and mixing the refined slag powder abrasive and the steel slag mixed powder abrasive in a mass ratio of 5:40 to obtain a mixed material;

[0058] (11) The specific surface area is 400m 2 / kg cement clinker and the mixture obtained in step (10) are homogenized and mixed in a mass ratio of 50:50 to obtain low-cost, non-burning, fast-hardening steel slag cement.

[0059] The low-cost, unburned, fast-hardening steel slag cements of Comparative Examples 2 and 3 were prepared according to the method of Comparative Example 1. The amounts of various materials used and the properties of the prepared cements are shown in Table 1.

[0060] Table 1 Amount of each component used and properties of the prepared cement in the examples and comparative examples

[0061]

[0062]

[0063] Note: (1) Steel slag powder is the undersize steel slag powder mixed with limestone and gypsum; (2) Refined slag powder abrasive 1 comes from block refined slag, which is the oversize material obtained by sieving the refined slag with a 15 mm × 15 mm sieve; (3) Refined slag powder abrasive 2 comes from powdered refined slag, which is the undersize material obtained by sieving the refined slag with a 15 mm × 15 mm sieve; (4) The amount of each component is the mass ratio.

[0064] Refined slag is an alkaline slag rich in Al2O3 and CaO. The performance of its block and powder is quite different. The block part mainly exists in the form of Ca(AlO2)2. The addition of Ca(AlO2)2 can enhance the early strength of cement; while the powder part is mainly inactive dicalcium silicate. Therefore, separating the block and powder of refined slag can effectively retain the effective components of the block material and better retain the rapid hardening property of the prepared slag cement. Steps (5) to (7) in Example 1 are to separate the block and powder materials of refined slag, and select block materials (i.e., the screened material obtained by screening with a 15mm×15mm screen in the preparation method) to prepare the low-cost, non-burning, rapid-hardening slag cement of the present invention.

[0065] Substituting part of cement clinker with block refined slag or powder refined slag for comparison, it can be seen from Table 1 that the cement prepared with block refined slag as raw material has a 7-day gelling activity index that is 15.0% to 19.0% higher than that without adding, and is also higher than that of cement using powder refined slag; the 28-day gelling activity index is 15.0% to 18.0% higher than that without adding, and is also higher than that of cement adding powder refined slag. This shows that adding part of block refined slag material with good rapid hardening property makes the product have better gelling property, which can partially replace cement clinker for preparing steel slag rapid hardening cement, and obtain low-cost non-burning gelling material with good early strength.

[0066] The method of the present invention firstly washes and screens the steelmaking refined slag after natural cooling and iron removal to obtain the material on the 15mm×15mm mesh screen, and then grinds it into 350-450m 2 / kg of refined slag powder abrasive, this part of the refined slag retains the highly active calcium aluminate component, and the inactive refined slag part of the powder under the 15mm×15mm sieve is removed. In addition, steel slag powder, gypsum and limestone are homogenized and mixed in a mass ratio of 20-40:3-8:3-8 to obtain a specific surface area of ​​500m 2 / kg or more of steel slag mixed powder and abrasive, then the refined slag powder and the steel slag mixed powder and abrasive are homogenized and mixed in a mass ratio of 0-10:40, and finally the cement clinker and the mixed material obtained by the above homogenization are homogenized and mixed in a mass ratio of 50-60:40-50 to obtain low-cost, unburned, fast-hardening steel slag cement, whose 7-day activity can reach 80% and 28-day activity can reach more than 85%.

[0067] Although the specific implementation of the present invention is described in detail in conjunction with the embodiments, it should not be understood as limiting the scope of protection of this patent. Within the scope described in the claims, various modifications and variations that can be made by those skilled in the art without creative work still fall within the scope of protection of this patent.

Claims

1. A method for preparing low-cost, non-burning, rapid-hardening steel slag cement, characterized in that: The following steps are involved: (1) crushing the steel slag powder, and screening it with a 3 mm×3 mm sieve to obtain sieved steel slag powder and sieved steel slag powder; the sieved steel slag powder is recycled; (2) homogenizing and mixing the sieved steel slag powder, gypsum and limestone in a mass ratio of 20-40:4-6:4-6; (3) Grind the homogenized and mixed materials to a specific surface area of ​​450-550m 2 / kg, to obtain steel slag mixed powder abrasive; (4) Screening the refined slag using a 15 mm × 15 mm sieve to obtain the material above the sieve and the material below the sieve; (5) subjecting the above-screen material to magnetic separation to separate the iron-containing material and the magnetic separation residue; (6) washing the magnetic separation residue, drying it until the moisture content is less than 5%, and then crushing it. After crushing, sieving it with a 3 mm×3 mm sieve to obtain sieve-surface refined slag and sieve-under refined slag; the sieve-surface refined slag is reused; (7) Grinding the under-sieve refined slag to a specific surface area of ​​350-450m 2 / kg, refined slag powder abrasive is obtained; (8) homogenizing and mixing the refined slag powder abrasive and the steel slag mixed powder abrasive in a mass ratio of 1 to 10:40 to obtain a mixed material; (9) The cement clinker powder and the mixed powder are homogenously mixed in a mass ratio of 50-60:40-50 to obtain the product.

2. The method for preparing low-cost, non-burning, rapid-hardening steel slag cement according to claim 1, characterized in that: The method for recycling the steel slag powder on the screen is as follows: subjecting the steel slag powder on the screen to magnetic separation to separate the iron-containing material in the steel slag powder and the magnetic separation residue of the steel slag powder, and returning the magnetic separation residue of the steel slag powder to the crushing equipment for crushing together with the steel slag powder in the step (1); the method for recycling the refined slag on the screen is as follows: subjecting the refined slag on the screen to magnetic separation to separate the iron-containing material in the refined slag and the magnetic separation residue of the refined slag; and returning the magnetic separation residue of the refined slag to the crushing equipment for crushing together with the magnetic separation residue rinsed and dried in the step (6).

3. The method for preparing low-cost, non-burning, rapid-hardening steel slag cement according to claim 2, characterized in that: The magnetic field intensity for magnetic separation of the above-sieve steel slag powder and the above-sieve refined slag is 2500-3000 Gauss.

4. The method for preparing low-cost, non-burning, rapid-hardening steel slag cement according to claim 1, characterized in that: The equipment for crushing in step (1) and step (6) is a double roll crusher, a rod mill or a roller mill, the equipment for grinding in step (3) and step (7) is a roller mill or a ring roller mill, and the magnetic field strength for magnetic separation in step (5) is 1800 to 2000 Gauss.

5. The method for preparing low-cost, non-burning, rapid-hardening steel slag cement according to claim 1, characterized in that: The mass ratio of the mixed under-sieve steel slag powder, gypsum and limestone is 30:5:

5.

6. The method for preparing low-cost, non-burning, rapid-hardening steel slag cement according to claim 1, characterized in that: In step (3), the powder is ground to a specific surface area of ​​500 m 2 / kg; in step (7), the powder is ground to a specific surface area of ​​400m 2 / kg.

7. The method for preparing low-cost, non-burning, rapid-hardening steel slag cement according to claim 1, characterized in that: The magnetic separation residue is rinsed and air-dried to a moisture content of 3.7%.

8. The method for preparing low-cost, non-burning, rapid-hardening steel slag cement according to claim 1, characterized in that: The mass ratio of the refined slag powder abrasive to the steel slag mixed powder abrasive is 5:

40.

9. The method for preparing low-cost, non-burning, rapid-hardening steel slag cement according to claim 1, characterized in that: The specific surface area of ​​the cement clinker powder is 400m 2 / kg, the mass ratio of the cement clinker and the mixed grinding material is 50:

50.

10. Low-cost, non-burning, rapid-hardening steel slag cement prepared by the preparation method according to any one of claims 1 to 9.

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