1. The sulphoaluminate modified carbon steel slag is characterized in that the preparation method comprises the following steps:

(1) preparing a mixture: taking the weight ratio of 3-5: 1, mixing the carbon steel slag and the modifier to form a mixture A;

(2) and (3) pressing and forming: pressurizing the mixture A for 10 seconds by using a die with the inner diameter of 30mm and a pressure machine with the force of 50kN, and pressing the mixture into a material cake B with the diameter of 30mm and the thickness of 9 mm;

(3) and (3) calcining: calcining the material cake B in the step (2) in a high-temperature furnace at 1220-1230 ℃ for 50-200min to form a material cake C;

(4) quenching: cooling the material cake C generated in the step (3) in a high-temperature furnace, taking out the material cake C when the temperature is reduced to 700 ℃, and rapidly cooling the material cake C to room temperature to obtain sulphoaluminate modified carbon steel slag D;

(5) milling: grinding the sulphoaluminate modified carbon steel slag D quenched in the step (4) into the specific surface area of 200m by using a disc grinder²About one kg of fine powder, then 5 percent of dihydrate gypsum is added as grinding aid to be ball-milled with the modified carbon steel slag into powder with the specific surface area of 350m²Per kg of modified carbon steel slag powder.

2. The aluminate modified carbon steel slag according to claim 1, characterized in that: the carbon steel slag comprises the following main chemical components in percentage by mass: 42.3 to 47.6 percent of CaO and SiO₂ 8.5%~12%、MnO₂ 0.7%~4.3%、MgO 3.3%~7.2%、Al₂O₃ 1.6%~5.25%、Fe_xO_y 28.5%~33.4%。

3. The aluminate modified carbon steel slag according to claim 2,the method is characterized in that: the carbon steel slag is put into a drying box to be dried at 105 ℃ until the water content is less than 1 percent before being mixed, and is ground into the carbon steel slag with the specific surface area of 350m by a disc grinder and a ball mill²Per kg of carbon steel slag powder.

4. The aluminate modified carbon steel slag according to claim 1, characterized in that: the modifier is prepared from (by weight ratio) 2-4: 1 fly ash and beta-type semi-hydrated gypsum.

5. The aluminate modified carbon steel slag according to claim 4, wherein: the fly ash comprises the following main chemical components in percentage by mass: CaO 2.6-6.5%, SiO₂ 48.1%~52.7%、Al₂O₃ 23.8%~28.3%、Fe₂O₃3.7%~8.18%。

6. The aluminate modified carbon steel slag according to claim 4, wherein:

the beta-type semi-hydrated gypsum comprises the following main chemical components in percentage by mass: 36.57-40.78% of CaO and SiO₂1.25%~5.43%、Al₂O₃ 0.33%~0.85%、Fe₂O₃ 0.1%~0.49%、SO₃ 38.63%~43.76%。

7. The aluminate modified carbon steel slag according to claim 5, characterized in that: and drying the fly ash before mixing until the water content is lower than 1%.

8. The aluminate modified carbon steel slag according to claim 1, characterized in that: and (4) quenching in the step (4) is specifically to blow by a high-power electric fan at room temperature after being taken out, and the cooling rate is kept at 120 and 140 ℃/min.

9. The use method of the sulphoaluminate modified carbon steel slag is characterized by comprising the following steps: taking the sulphoaluminate modified carbon steel slag of any one of claims 1 to 8 and cement in a mass ratio of 3: 7 at normal temperature and pressure.

Background

The steel slag is solid waste obtained by cooling molten waste with the temperature above 1400 ℃ in the steel making process. The discharge amount of the steel slag is about 10-15% of the steel yield. According to the data of the national statistical bureau, the yield of the crude steel in China in 2017 is 83172.8 ten thousand tons, and the yield is increased by 5.7 percent on the same scale, so the yield of the steel slag in 2017 is about 10812.5 ten thousand tons. In the state 'fifteen-over-ten development plan', the comprehensive utilization rate of the steel slag is required to reach more than 86%, zero emission is basically realized, however, the current situation of the Chinese comprehensive utilization is far away from the plan, so far, the comprehensive utilization rate of the steel slag is only 30%, and a great space is provided for improvement.

The steel slag contains a large amount of gelled minerals, but because of the steel-making system, a plurality of impurity components are also introduced into the steel slag, and the steel slag can be considered as silicate cement clinker with lower gelling activity. The main reasons for the low gelling activity of steel slag are: firstly, the content of inactive substances in the steel slag is high, which results in silicic acidThe content of salt minerals is low, and only accounts for about 30 percent; secondly, the temperature can reach 1650 ℃ at most in the steel-making process, the temperature exceeds the calcining temperature of the cement clinker, and the excessive temperature can lead C₃S、C₂S and other minerals become compact inside, the crystal lattice grows completely, and the hydration is difficult. If a proper method is adopted, the activity of the steel slag can be greatly excited.

Therefore, if the comprehensive utilization rate of the steel slag is to be improved, a proper modifier is added into the steel slag in a reasonable mode to change the chemical components of the steel slag, so that the utilization rate of the steel slag can be greatly improved, and waste materials are changed into valuable materials. At present, the modifying agent is commonly added into hot steel slag, and the temperature of the steel slag just discharged from a steel-making furnace is about 1600 ℃, and the temperature can be utilized. The mixing amount of each modifier is calculated through calculation, the mixed modifier is added into the hot steel slag after the steel slag is discharged, the steel slag and the modifier are fully reacted to generate useful mineral components, and the residual temperature of the steel slag is utilized, so that the modification purpose can be achieved, the cost can be saved, but the operation mode has operation difficulty and cost improvement.

Disclosure of Invention

The invention provides sulphoaluminate modified carbon steel slag and a using method thereof, and solves the problems of operation difficulty and cost increase of the conventional carbon steel slag modification.

In order to solve the technical problem, the technical scheme of the invention is realized as follows:

the preparation method of the sulphoaluminate modified carbon steel slag comprises the following steps:

(1) preparing a mixture: taking the weight ratio of 3-5: 1, mixing the carbon steel slag and the modifier to form a mixture A;

(2) and (3) pressing and forming: pressurizing the mixture A for 10 seconds by using a die with the inner diameter of 30mm and a pressure machine with the force of 50kN, and pressing the mixture into a material cake B with the diameter of 30mm and the thickness of 9 mm; if the material cake is too thick, all raw materials in the mixture can not completely participate in the solid-phase reaction, and if the material cake is too thin, the material cake is easy to crack after being pressed;

(3) and (3) calcining: calcining the material cake B in the step (2) in a high-temperature furnace at 1220-1230 ℃ for 50-200min to form a material cake C; in the temperature range, the cake B has a micro-melting phenomenon, which is beneficial to solid-phase reaction of various substances, if the temperature is higher than the temperature range, the cake B is molten, and if the temperature is lower than the temperature range, various reactants in the cake B can not completely participate in the solid-phase reaction, so that the content of a target product is reduced, and the content of an irrelevant product is increased;

(4) quenching: cooling the material cake C generated in the step (3) in a high-temperature furnace, taking out the material cake C when the temperature is reduced to 700 ℃, and rapidly cooling the material cake C to room temperature to obtain sulphoaluminate modified carbon steel slag D;

(5) milling: grinding the sulphoaluminate modified carbon steel slag D quenched in the step (4) into the specific surface area of 200m by using a disc grinder²About one kg of fine powder, then 5 percent of dihydrate gypsum is added as grinding aid to be ball-milled with the modified carbon steel slag into powder with the specific surface area of 350m²Per kg of modified carbon steel slag powder. The dihydrate gypsum is 5 percent of the sulphoaluminate modified carbon steel slag D in mass. The added dihydrate gypsum is 5% of the mass of the quenched sulphoaluminate modified carbon steel slag, 5% of dihydrate gypsum is required to be added as a grinding aid during grinding of cement according to the standard requirement, and the gypsum has the function of retarding coagulation.

Preferably, the carbon steel slag comprises the following main chemical components in percentage by mass: 42.3 to 47.6 percent of CaO and SiO₂ 8.5%~12%、MnO₂ 0.7%~4.3%、MgO 3.3%~7.2%、Al₂O₃ 1.6%~5.25%、Fe_xO_y 28.5%~33.4%。

Wherein, preferably, the carbon steel slag is placed into a drying box for drying at 105 ℃ until the water content is less than 1 percent before mixing, and is ground into the carbon steel slag with the specific surface area of 350m by a disc grinder and a ball mill²Per kg of carbon steel slag powder.

Wherein, preferably, the modifier is prepared by mixing the components in a weight ratio of 2-4: 1 fly ash and beta-type semi-hydrated gypsum.

Preferably, the fly ash comprises the following main chemical components in percentage by mass: CaO 2.6-6.5%, SiO₂ 48.1%~52.7%、Al₂O₃ 23.8%~28.3%、Fe₂O₃ 3.7%~8.18%。

Preferably, the beta-type semi-hydrated gypsum comprises the following main chemical components in percentage by mass: 36.57-40.78% of CaO and SiO₂ 1.25%~5.43%、Al₂O₃ 0.33%~0.85%、Fe₂O₃ 0.1%~0.49%、SO₃ 38.63%~43.76%

Wherein, preferably, the fly ash is dried to the water content of less than 1% before mixing.

Wherein, preferably, the quenching in the step (4) is specifically to blow by a high-power electric fan at room temperature after being taken out, and the cooling rate is kept at 120-.

The use method of the sulphoaluminate modified carbon steel slag comprises the following steps of taking the sulphoaluminate modified carbon steel slag and cement in a mass ratio of 3: 7 at normal temperature and pressure.

The modification principle of the modified carbon steel slag is as follows:

10CaO+SiO₂+6Al₂O₃+Fe₂O₃＝3CaO·3Al₂O₃·CaSO₄(calcium sulphoaluminate) +2 CaO. SiO₂(dicalcium silicate) +4CaO 3Al₂O₃·Fe₂O₃(tetracalcium aluminoferrite)

The three minerals in the reaction formula are all minerals with high gelling activity. In addition, tricalcium silicate is the main gelling mineral in ordinary portland cement, and the reaction formula is as follows:

3CaO+SiO₂＝3CaO·SiO₂

however, tricalcium silicate can only exist stably at 1250 ℃, and when the temperature is lower than 1250 ℃, the tricalcium silicate can be decomposed into dicalcium silicate (2 CaO. SiO) by slow cooling₂Also the main gelling mineral in ordinary portland cement) and calcium oxide, while dicalcium silicate belongs to metastable mineral, there are five crystal transformation in the cooling process, when the temperature is reduced from 1250 ℃, the crystal transformation starts (principle explanation), the transformation process is shown in fig. 1.

Wherein gamma type is inactive, so when the temperature is about 700 ℃, the dicalcium silicate crystal form is in the transition period of alpha and beta, the invention takes out the modified carbon steel slag C and takes a quenching measure, the crystal lattice of the modified carbon steel slag C is not in time to rearrange into gamma, and the beta type is reserved, according to the research, the invention shows that:

1) β -C2S is a metastable high-temperature mineral existing at normal temperature, and therefore its structure is thermodynamically unstable;

2) calcium ions in the beta-C2S have irregular coordination, so that the calcium ions have higher activity;

3) the presence of impurities and stabilizers in the beta-C2S structure also increases its structural activity.

The invention has the beneficial effects that:

(1) the fly ash and the beta-type semi-hydrated gypsum are added into the carbon steel slag for modification, wherein the carbon steel slag and the fly ash are industrial solid wastes and have the defects of large production amount and low utilization rate.

(2) In the preparation process of the sulphoaluminate modified carbon steel slag, the calcined carbon steel slag is treated by a quenching method, and the crystal form of dicalcium silicate is kept as a beta type in the quenching process, so that the dicalcium silicate modified carbon steel slag has higher structural activity. And the quenching method in the invention is simple, easy to operate and cost-saving.

(3) The carbon steel slag is mixed with cement mortar after the modifier is added, the activity index of the mortar test block is greatly improved, the activity indexes of 3d and 28d are both close to 100 percent at most, and the test block has good stability through testing and can be used as a mixed material to be doped into cement.

Drawings

Fig. 1 is a schematic diagram of the transformation principle of tricalcium silicate crystal form.

Detailed Description

The technical solutions of the present invention will be described clearly and completely with reference to specific embodiments of the present invention, and it should be understood that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Example 1

The embodiment provides sulphoaluminate modified carbon steel slag, and the preparation method comprises the following steps:

(1) preparing a mixture: taking the weight ratio of 4: 1, mixing the carbon steel slag and the modifier to form a mixture A; before mixing, the carbon steel slag is put into a drying box to be dried at 105 ℃ until the water content is 0.6 percent, and is ground into the carbon steel slag with the specific surface area of 350m by a disc grinder and a ball mill²Per kg of carbon steel slag powder; the modifier is prepared from the following components in a weight ratio of 3: 1, fly ash and beta-type semi-hydrated gypsum; drying the fly ash before mixing until the water content is 0.8%;

(2) and (3) pressing and forming: pressurizing the mixture A for 10 seconds by using a die with the inner diameter of 30mm and a pressure machine with the force of 50kN, and pressing the mixture into a material cake B with the diameter of 30mm and the thickness of 9 mm;

(3) and (3) calcining: calcining the material cake B in the step (2) in a high-temperature furnace at 1220-1230 ℃ for 120min to form a material cake C;

(4) quenching: cooling the material cake C generated in the step (3) in a high-temperature furnace, taking out the material cake C when the temperature is reduced to 700 ℃, and rapidly cooling to room temperature, wherein the rapidly cooling is specifically that after the material cake C is taken out, a high-power electric fan is adopted to blow the material cake C at room temperature, and the cooling rate is kept at 130 ℃/min, so that the sulphoaluminate modified carbon steel slag D is obtained;

(5) milling: grinding the sulphoaluminate modified carbon steel slag D quenched in the step (4) into the specific surface area of 200m by using a disc grinder²About one kg of fine powder, then 5 percent of dihydrate gypsum is added as grinding aid to be ball-milled with the modified carbon steel slag into powder with the specific surface area of 350m²Per kg of modified carbon steel slag powder.

The carbon steel slag comprises the following main chemical components in percentage by mass: CaO 45.2%, SiO₂ 9.2%、MnO₂ 2.1%、MgO 5.2%、Al₂O₃ 3.4%、Fe_xO_y 31.2%。

The fly ash comprises the following main chemical components in percentage by mass: CaO 4.5%, SiO₂ 50.1%、Al₂O₃ 25.9%、Fe₂O₃5.6%。

Wherein the beta form is hemihydrateThe main chemical components and the mass percentage content of the gypsum are as follows: 38.12% of CaO and SiO₂ 3.26、Al₂O₃ 0.59%、Fe₂O₃ 0.24%、SO₃ 40.24%。

Example 2

The embodiment provides sulphoaluminate modified carbon steel slag, and the preparation method comprises the following steps:

(1) preparing a mixture: taking the weight ratio of 3: 1, mixing the carbon steel slag and the modifier to form a mixture A; before mixing, the carbon steel slag is put into a drying box to be dried at 105 ℃ until the water content is 0.9 percent, and is ground into the carbon steel slag with the specific surface area of 350m by a disc grinder and a ball mill²Per kg of carbon steel slag powder; the modifier is prepared from (by weight ratio) 4: 1, fly ash and beta-type semi-hydrated gypsum; drying the fly ash before mixing until the water content is 1%;

(2) and (3) pressing and forming: pressurizing the mixture A for 10 seconds by using a die with the inner diameter of 30mm and a pressure machine with the force of 50kN, and pressing the mixture into a material cake B with the diameter of 30mm and the thickness of 9 mm;

(3) and (3) calcining: calcining the material cake B in the step (2) in a high-temperature furnace at 1220-1230 ℃ for 50-200min to form a material cake C;

(4) quenching: cooling the material cake C generated in the step (3) in a high-temperature furnace, taking out the material cake C when the temperature is reduced to 700 ℃, and rapidly cooling to room temperature, wherein the rapidly cooling is specifically that after the material cake C is taken out, a high-power electric fan is adopted to blow the material cake C at room temperature, and the cooling rate is kept at 120 ℃/min to obtain sulphoaluminate modified carbon steel slag D;

(5) milling: grinding the sulphoaluminate modified carbon steel slag D quenched in the step (4) into the specific surface area of 200m by using a disc grinder²About one kg of fine powder, then 5 percent of dihydrate gypsum is added as grinding aid to be ball-milled with the modified carbon steel slag into powder with the specific surface area of 350m²Per kg of modified carbon steel slag powder.

The carbon steel slag comprises the following main chemical components in percentage by mass: 42.3% of CaO and SiO₂ 12%、MnO₂ 0.7%、MgO 7.2%、Al₂O₃ 1.6%、Fe_xO_y 33.4%。

Wherein the fly ashThe main chemical components and the mass percentage content are as follows: CaO 2.6%, SiO₂ 52.7%、Al₂O₃ 23.8%、Fe₂O₃ 8.18%。

The beta-type semi-hydrated gypsum comprises the following main chemical components in percentage by mass: 36.57% of CaO and SiO₂ 5.43%、Al₂O₃ 0.33%、Fe₂O₃ 0.49%、SO₃ 38.63%。

Example 3

The embodiment provides sulphoaluminate modified carbon steel slag, and the preparation method comprises the following steps:

(1) preparing a mixture: taking the components in a weight ratio of 5: 1, mixing the carbon steel slag and the modifier to form a mixture A; before mixing, the carbon steel slag is put into a drying box to be dried at 105 ℃ until the water content is 1 percent, and is ground into the carbon steel slag with the specific surface area of 350m by a disc grinder and a ball mill²Per kg of carbon steel slag powder; the modifier is prepared from the following components in a weight ratio of 2: 1, fly ash and beta-type semi-hydrated gypsum; drying the fly ash before mixing until the water content is 0.6%;

(2) and (3) pressing and forming: pressurizing the mixture A for 10 seconds by using a die with the inner diameter of 30mm and a pressure machine with the force of 50kN, and pressing the mixture into a material cake B with the diameter of 30mm and the thickness of 9 mm;

(3) and (3) calcining: calcining the material cake B in the step (2) in a high-temperature furnace at 1220-1230 ℃ for 200min to form a material cake C;

(4) quenching: cooling the material cake C generated in the step (3) in a high-temperature furnace, taking out the material cake C when the temperature is reduced to 700 ℃, rapidly cooling the material cake C to room temperature, specifically, blowing the material cake C at room temperature by using a high-power electric fan after the material cake C is taken out, and keeping the cooling rate at 120-140 ℃/min to obtain sulphoaluminate modified carbon steel slag D;

(5) milling: grinding the sulphoaluminate modified carbon steel slag D quenched in the step (4) into the specific surface area of 200m by using a disc grinder²About one kg of fine powder, then 5 percent of dihydrate gypsum is added as grinding aid to be ball-milled with the modified carbon steel slag into powder with the specific surface area of 350m²Per kg of modified carbon steel slag powder.

Wherein, the carbon steel slag comprises the main chemical components and the massThe percentage content is as follows: 42.3 to 47.6 percent of CaO and SiO₂8.5%~12%、MnO₂ 0.7%~4.3%、MgO 3.3%~7.2%、Al₂O₃ 1.6%~5.25%、Fe_xO_y 28.5%~33.4%。

The fly ash comprises the following main chemical components in percentage by mass: CaO 2.6-6.5%, SiO₂48.1%~52.7%、Al₂O₃ 23.8%~28.3%、Fe₂O₃ 3.7%~8.18%。

The beta-type semi-hydrated gypsum comprises the following main chemical components in percentage by mass: 36.57-40.78% of CaO and SiO₂ 1.25%~5.43%、Al₂O₃ 0.33%~0.85%、Fe₂O₃ 0.1%~0.49%、SO₃ 38.63%~43.76%。

Example 4

The embodiment provides sulphoaluminate modified carbon steel slag, and the preparation method comprises the following steps:

(1) preparing a mixture: taking the components in a weight ratio of 3.5: 1, mixing the carbon steel slag and the modifier to form a mixture A; before mixing, the carbon steel slag is put into a drying box to be dried at 105 ℃ until the water content is 0.6 percent, and is ground into the carbon steel slag with the specific surface area of 350m by a disc grinder and a ball mill²Per kg of carbon steel slag powder; the modifier is prepared from the following components in a weight ratio of 3.5: 1, fly ash and beta-type semi-hydrated gypsum; drying the fly ash before mixing until the water content is 0.8%;

(2) and (3) pressing and forming: pressurizing the mixture A for 10 seconds by using a die with the inner diameter of 30mm and a pressure machine with the force of 50kN, and pressing the mixture into a material cake B with the diameter of 30mm and the thickness of 9 mm;

(3) and (3) calcining: calcining the material cake B in the step (2) in a high-temperature furnace at 1220-1230 ℃ for 150min to form a material cake C;

(4) quenching: cooling the material cake C generated in the step (3) in a high-temperature furnace, taking out the material cake C when the temperature is reduced to 700 ℃, and rapidly cooling to room temperature, wherein the rapidly cooling is specifically that after the material cake C is taken out, a high-power electric fan is adopted to blow the material cake C at room temperature, and the cooling rate is kept at 135 ℃/min, so that the sulphoaluminate modified carbon steel slag D is obtained;

(5) milling: sulphoaluminate modified carbon steel slag quenched in step (4)D, firstly grinding the mixture into a specific surface area of 200m by using a disc grinder²About one kg of fine powder, then 5 percent of dihydrate gypsum is added as grinding aid to be ball-milled with the modified carbon steel slag into powder with the specific surface area of 350m²Per kg of modified carbon steel slag powder.

The carbon steel slag comprises the following main chemical components in percentage by mass: CaO 43.2%, SiO₂ 11.2%、MnO₂ 3.8%、MgO 5.2%、Al₂O₃ 3.8%、Fe_xO_y 30.2%。

The fly ash comprises the following main chemical components in percentage by mass: CaO 3.5%, SiO₂ 50.6%、Al₂O₃ 26.7%、Fe₂O₃ 6.72%。

The beta-type semi-hydrated gypsum comprises the following main chemical components in percentage by mass: 38.21 percent of CaO and SiO₂ 3.26、Al₂O₃ 0.65%、Fe₂O₃ 0.25%、SO₃ 40.12%。

Application example

The sulphoaluminate modified carbon steel slag is used as a mixed material to be doped into P.I cement, the mixed material is prepared into a standard sample of 40mm multiplied by 160mm according to GB/T17671-1999 Cement mortar Strength test method (ISO method), the flexural strength and the compressive strength of the standard sample are tested after the standard sample is maintained to a specified age period, and the mortar test result is shown in Table 1:

TABLE 1 mortar test results

Note: the 0 group is the P.I cement mortar test result; the S0 group is formed by grinding carbon steel slag and P.I cement in a ratio of 3: 7, testing results of the mortar after mixing according to the proportion; s1 to S4 represent the sulphoaluminate modified carbon steel slag of examples 1 to 4 and P.I cement, respectively, in a ratio of 3: 7, and (3) the mortar test result after mixing.

The result shows that after the modifier is added, the activity index of the mortar test block is greatly improved, the activity indexes of 3d and 28d are both close to 100 percent at most, and the test block has good stability and can be used as a mixed material to be doped into cement.

The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements, etc. made within the spirit and principles of the present invention are intended to be included within the scope of the present invention.