Cement raw material suitable for solar concentrating firing and application of cement raw material

Abstract

The invention relates to the technical field of cement manufacturing, in particular to a cement raw material suitable for solar concentrating firing and application of the cement raw material. The three-rate value of the raw material and the content of Co3O4 + MnO2 are regulated and controlled, isopropanol is utilized for sufficient homogenization after grinding is conducted, the absorption capacity of the raw material to the full spectrum of the sun is improved, and the utilization rate of the raw material is increased; the free calcium oxide value of the cement clinker sintered by the solar concentrating equipment is low, and the compressive strength meets the standard requirement.

Description

Technical Field

[0001] The invention relates to the technical field of cement manufacturing, in particular to a cement raw material suitable for solar concentrated firing and application thereof. Background Art

[0002] The preparation of Portland cement clinker is a highly energy-intensive production process. Most of the carbon dioxide emissions from cement manufacturing come from limestone decarbonization and the burning of fossil fuels, accounting for 5% of global anthropogenic carbon dioxide emissions and 7% of industrial fuel use, respectively. Solar concentrating high-temperature technology generates high temperatures in a short period of time by concentrating solar energy, and the concentrated light spot has extremely high energy. It has great potential for application in the clinker calcination step in the cement production process. This technology is in the leading exploration stage and can be used to replace coal / gas / electricity to calcine cement clinker in the future, helping the cement industry to transform its energy and achieve low-carbon development as soon as possible.

[0003] At present, most of the high-temperature research on solar concentrating focuses on the development of reactors, but there is little research on the spectral absorption capacity of materials under such conditions. The weighted absorption ratio of sunlight within a certain wavelength range can reflect the light absorption performance of particles. Therefore, when using solar concentrating to burn cement clinker, it is necessary to study methods to improve the absorption capacity of cement raw materials to sunlight. Summary of the invention

[0004] In order to solve the problems existing in the prior art, the present invention provides a cement raw material suitable for solar energy concentration firing, and clinker and cement prepared by using the same. In the prior art, silicate cement raw material has a large reflection coefficient when directly fired into clinker by concentrated irradiation, and thus cannot be fired by solar energy concentration. The present invention improves the raw material's ability to absorb sunlight by changing the raw material composition and the output value of metal oxides, thereby facilitating the effective utilization of energy during concentrated firing. Specifically, by regulating the raw material's three-rate value and Co3O4+MnO2 content, the raw material is fully homogenized with isopropanol after grinding, thereby improving the raw material's ability to absorb the full spectrum of sunlight. The cement clinker fired by solar energy concentration equipment has a low free calcium oxide value and its compressive strength meets standard requirements.

[0005] Specifically, the present invention is applicable to a process for preparing cement raw materials fired by solar concentrated firing, comprising the following steps: 1) Detect the chemical composition of the raw materials and calculate the ingredients according to the designed three-rate value and Co3O4+MnO2 content. 2) Mix the raw materials according to the mass ratio, add appropriate amount of grinding aid and perform ball milling to obtain powder. 3) Mix the powder and isopropyl alcohol thoroughly and dry them.

[0006] The invention takes silicate cement as the design basis, and the raw materials are homogenized by physical mixing, ball milling and isopropyl alcohol, so that two metal oxides, Co3O4 and MnO2, are evenly dispersed in the raw material, and the effective admixture amount can be increased, thereby obtaining a cement raw material suitable for solar concentrated firing and having extremely strong absorption capacity in a wide ultraviolet, visible and infrared spectrum range.

[0007] Preferably, the raw materials in step 1) are composed of calcium raw materials, clay raw materials, steel slag, cobalt-manganese slag and nickel-containing waste slag.

[0008] Preferably, the calcium raw material is limestone.

[0009] Preferably, the clay raw material is sandstone.

[0010] Preferably, in step 1), the three rate values ​​are IM=1.50±0.03, KH=0.90±0.03, and SM=2.47±0.03.

[0011] The three rates of cement raw material have a certain influence on the formation and state of the liquid phase in the clinker, and directly affect the light absorption capacity. The present invention conducts a large number of experimental studies on the changes in the three rates at low temperatures and the influence of Co3O4+MnO2 content on the spectral energy absorption of the raw material in the selected band, as well as the photothermal conversion capacity, and finally selects the above three rates.

[0012] Preferably, in step 1), the content of Co3O4+MnO2 is 0.75-3%.

[0013] The acquisition of cement clinker undergoes three major physical and chemical changes, mainly carbonate decomposition, solid phase reaction, liquid phase and clinker sintering. The large amount of tricalcium silicate, the main mineral, marks the burning of cement clinker. Steel slag and cobalt-manganese slag are wastes generated in the industrial production process. They contain the main oxides SiO2, CaO and Al2O3 in cement raw materials and some Mn and Co metal elements that are difficult to extract. The main component of nickel-containing waste slag is calcium oxide. The present invention adds steel slag, cobalt-manganese slag and nickel-containing waste slag as correction materials to introduce Co3O4 and MnO2 The two metal oxides not only act as light absorption enhancers to promote the overall absorption coefficient of raw materials to sunlight in the low-temperature irradiation stage, but also undergo mutations under high-temperature conditions, and play the role of mineralizer / fluxing agent in the sintering process of silicate cement clinker, thereby promoting the formation of liquid phase, which is beneficial to improving the burnability. In addition, the combined use of the two has a small effect on the mineral content and development of the synthetic clinker in the high-temperature stage, but the improvement of the overall light absorption and photothermal conversion capacity of the raw materials is very obvious, so it is suitable for cement raw materials to be fired in solar energy concentrating equipment. In addition, in the preparation process of the present invention, harmful components such as zinc and manganese and other heavy metals are solidified during the preparation of cement clinker, and the waste residue disposal has basically no deterioration effect on the standard consistency water consumption, setting time, and compressive strength of the finished cement product.

[0014] Preferably, in step 3), the mass ratio of powder to isopropanol is 1:(0.9-1.5).

[0015] Preferably, in step 3), the drying temperature is 55-70° C. and the drying time is 48-188 h.

[0016] The present invention also relates to cement raw material suitable for solar concentrated firing, which is specifically prepared by the above-mentioned preparation process.

[0017] The present invention also relates to cement clinker, which is specifically formed by burning the above-mentioned cement raw material in a solar energy concentrating device.

[0018] The present invention also relates to cement, which is specifically prepared by mixing and ball-milling the above-mentioned cement clinker and gypsum. More preferably, the gypsum accounts for 4-6% of the mass of the clinker.

[0019] The invention also relates to the application of the cement in the production of building materials.

[0020] The present invention has the following technical advantages: 1. The process of the present invention is simple, the raw materials are easily available, and the raw materials have high energy absorption capacity in the 200-2500nm spectrum. 2. The present invention can utilize industrial waste residue and renewable energy to burn clinker, which has good energy-saving effect. 3. The clinker prepared by the present invention is of qualified quality and the cement strength meets the standard requirements. DETAILED DESCRIPTION

[0021] In order to characterize the technical effect of the present invention, cement raw materials were prepared to test the sunlight weighted absorption performance and room temperature light-to-heat conversion capacity, which can indirectly reflect the overall absorption capacity of the raw materials in the ultraviolet, visible and near-infrared spectrum range. Then, the cement clinker was fired using a solar energy concentrating firing system and the free calcium oxide content was tested. Then, 5% gypsum was added and ground to a specific surface area of ​​320±5m 2 / kg cement was prepared, and the cement slurry was made into shape and cured for 28 days before the compressive strength test. In the sunlight weighted absorption performance test, the spectrophotometer model was UH-4150, and the test conditions were: scanning range 200-2500nm, scanning speed 300nm / min, sampling interval 0.50nm, slit width 4.00nm, and room temperature photothermal conversion capacity test. 1.5g of cement raw material was pressed under a pressure of 10MPa to obtain a disc with a diameter of 2.6cm. The photothermal conversion capacity test conditions were a light power of 100W / m 2 The test time is 30 minutes; the recording time interval is every 5 seconds for 0-1 minute, every 10 seconds for 2-5 minutes, every 30 seconds for 6-20 minutes, and every 2 minutes for 21-30 minutes.

[0022] Example 1, cement raw material, the preparation process steps are: 1) Detect the chemical composition of limestone, sandstone, steel slag, cobalt-manganese slag and nickel-containing waste slag, and calculate the ingredients according to the design three-rate values ​​IM=1.50, KH=0.90, SM=2.49 and Co3O4+MnO2 content of 0.75%. 2) Mix the raw materials according to the mass ratio, add appropriate amount of grinding aid and perform ball milling to obtain powder. 3) Mix the powder and isopropyl alcohol in a mass ratio of 1:1 and dry to obtain the product.

[0023] After testing, the weighted absorption ratio of cement raw material spectrum is 29.5%, the highest temperature during photothermal conversion heating is 74.1℃, the maximum temperature difference is 44.1℃, the f-CaO content of clinker is 1.4%, the 3d compressive strength of cement slurry specimen is 24.2MPa, the 7d compressive strength is 36.7MPa, and the 28d compressive strength is 51.9MPa.

[0024] Example 2, cement raw material, the preparation process steps are: 1) Test the chemical composition of limestone, sandstone, steel slag, cobalt-manganese slag and nickel-containing waste slag, and calculate the proportioning according to the designed three-rate values ​​IM=1.51, KH=0.89, SM=2.47 and Co3O4+MnO2 content of 1.5%. 2) Mix the raw materials according to the mass ratio, add appropriate amount of grinding aid and perform ball milling to obtain powder. 3) Mix the powder and isopropyl alcohol in a mass ratio of 1:1.2 and dry to obtain the product.

[0025] After testing, the weighted absorption ratio of cement raw material spectrum is 33.4%, the highest temperature during photothermal conversion heating is 85.7℃, the maximum temperature difference is 52.7℃, the f-CaO content of clinker is 0.9%, the 3d compressive strength of cement slurry specimen is 26.5MPa, the 7d compressive strength is 40.2MPa, and the 28d compressive strength is 55.1MPa.

[0026] Example 3, cement raw material, the preparation process steps are: 1) Test the chemical composition of limestone, sandstone, steel slag, cobalt-manganese slag and nickel-containing waste slag, and calculate the proportioning according to the designed three-rate values ​​IM=1.51, KH=0.90, SM=2.5 and Co3O4+MnO2 content of 3%. 2) Mix the raw materials according to the mass ratio, add appropriate amount of grinding aid and perform ball milling to obtain powder. 3) Thoroughly mix the powder and isopropyl alcohol in a mass ratio of 1:1.5 and dry to obtain the product.

[0027] After testing, the weighted absorption ratio of cement raw material spectrum is 35.6%, the highest temperature during photothermal conversion heating is 79.2℃, the maximum temperature difference is 49.0℃, the f-CaO content of clinker is 0.6%, the 3d compressive strength of cement slurry specimen is 26.7MPa, the 7d compressive strength is 39.8MPa, and the 28d compressive strength is 56.4MPa.

[0028] Blank example, cement raw material, preparation process steps are: 1) Test the chemical composition of limestone, sandstone and steel slag, and calculate the proportioning according to the designed three-rate values ​​IM=1.50, KH=0.90 and SM=2.47. 2) Mix the raw materials according to the mass ratio, add appropriate amount of grinding aid and perform ball milling to obtain powder. 3) Mix the powder and isopropyl alcohol in a mass ratio of 1:1 and dry to obtain the product.

[0029] According to the test, the weighted absorption ratio of cement raw material spectrum is 9.2%, the highest temperature during photothermal conversion heating is 69.7℃, the maximum temperature difference is 40.1℃, the f-CaO content of clinker is 1.9%, the 3d compressive strength of cement slurry specimen is 21.3MPa, the 7d compressive strength is 34.1MPa, and the 28d compressive strength is 48.9MPa.

[0030] Comparative Example 1, cement raw material, the preparation process steps are: 1) Test the chemical composition of limestone, sandstone, steel slag, cobalt-manganese slag and nickel-containing waste slag, and calculate the proportioning according to the designed three-rate values ​​IM=1.51, KH=0.90, SM=2.5 and Co3O4+MnO2 content of 3%. 2) Mix the raw materials according to the mass ratio, add appropriate amount of grinding aid and ball mill to obtain.

[0031] After testing, the weighted absorption ratio of cement raw material spectrum is 17.2%, the highest temperature during photothermal conversion heating is 70.5℃, the maximum temperature difference is 41.6℃, the f-CaO content of clinker is 1.6%, the 3d compressive strength of cement slurry specimen is 22.9MPa, the 7d compressive strength is 35.2MPa, and the 28d compressive strength is 49.6MPa.

[0032] Comparative Example 2, cement raw material, the preparation process steps are: 1) Test the chemical composition of limestone, sandstone, steel slag, cobalt-manganese slag and nickel-containing waste slag, and calculate the proportioning according to the designed three-rate values ​​IM=1.38, KH=0.96, SM=2.0 and Co3O4+MnO2 content of 3%. 2) Mix the raw materials according to the mass ratio, add appropriate amount of grinding aid and perform ball milling to obtain powder. 3) Thoroughly mix the powder and isopropyl alcohol in a mass ratio of 1:1.5 and dry to obtain the product.

[0033] After testing, the weighted absorption ratio of cement raw material spectrum is 10.3%, the highest temperature during photothermal conversion heating is 69.3℃, the maximum temperature difference is 41.5℃, the f-CaO content of clinker is 2.3%, the 3d compressive strength of cement slurry specimen is 19.8MPa, the 7d compressive strength is 32.7MPa, and the 28d compressive strength is 45.0MPa.

[0034] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A process for preparing cement raw material suitable for solar concentrated firing, characterized in that: The following steps are involved: 1) Detect the chemical composition of the raw materials and calculate the ingredients according to the designed three-rate value and Co3O4+MnO2 content. 2) Mix the raw materials according to the mass ratio, add appropriate amount of grinding aid and perform ball milling to obtain powder. 3) Mix the powder and isopropyl alcohol thoroughly and dry them.

2. The process for preparing cement raw material suitable for solar concentrated firing according to claim 1, characterized in that: In step 1), the raw materials are composed of calcium raw materials, clay raw materials, steel slag, cobalt-manganese slag and nickel-containing waste slag.

3. The process for preparing cement raw material suitable for solar concentrated firing according to claim 2, characterized in that: The calcium raw material is limestone.

4. The process for preparing cement raw material suitable for solar concentrated firing according to claim 2, characterized in that: The clay raw material is sandstone.

5. The process for preparing cement raw material suitable for solar concentrated firing according to claim 1, characterized in that: Step 1) The three rate values ​​are IM=1.50±0.03, KH=0.90±0.03, SM=2.47±0.

03.

6. The process for preparing cement raw material suitable for solar concentrated firing according to claim 1, characterized in that: Step 1) The content of Co3O4+MnO2 is 0.75-3%.

7. The process for preparing cement raw material suitable for solar concentrated firing according to claim 1, characterized in that: Step 3) Add powder and isopropanol in a mass ratio of 1:(0.9-1.5).

8. A cement raw material suitable for solar concentrated burning, characterized in that: The invention is prepared by the preparation process according to any one of claims 1 to 7.

9. A cement clinker, characterized in that: The cement raw material according to claim 8 is fired in a solar concentrating device.

10. A cement, characterized in that: The cement clinker and gypsum are mixed and ball-milled to obtain the cement clinker.