Cement raw material suitable for solar concentrated firing and its application

Abstract

The present invention relates to the technical field of cement manufacturing, and in particular to a cement raw meal suitable for solar concentrating firing and applications thereof. By regulating the three rates and the content of Co3O4+MnO2 in the raw meal, the raw meal is fully homogenized using isopropyl alcohol after being ground, thereby improving the raw meal's ability to absorb the full solar spectrum. After firing using solar concentrating equipment, the cement clinker has a low free calcium oxide value and compressive strength that meets standard requirements.

Description

Technical Field

[0001] The present 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 production of Portland cement clinker is a highly energy-intensive process. Most CO2 emissions from cement manufacturing come from limestone decarbonization and fossil fuel combustion, accounting for 5% of global anthropogenic CO2 emissions and 7% of industrial fuel use, respectively. Concentrated solar high-temperature technology, which concentrates solar energy to generate high temperatures in a short period of time and produces extremely high energy, has great potential for application in the clinker calcination step of the cement production process. This technology is in the advanced exploration stage and could be used in the future to replace coal, gas, or electricity for cement clinker calcination, helping the cement industry transition to an energy-efficient manner and achieve low-carbon development.

[0003] Currently, research on high-temperature solar concentrating technology focuses primarily on reactor development, but little research is conducted on the spectral absorption capacity of materials under these conditions. The weighted absorption ratio of sunlight within a specific wavelength range can reflect the particle's light absorption properties. Therefore, when using solar concentrating technology to produce cement clinker, it is necessary to investigate methods to improve the cement raw material's ability to absorb 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 concentrated firing, as well as clinker and cement prepared 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 therefore cannot be fired using solar concentrated irradiation. 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 using isopropyl alcohol after grinding, thereby improving the raw material's ability to absorb the entire solar spectrum. The cement clinker fired using solar concentrating equipment has a low free calcium oxide value and compressive strength that meets standard requirements.

[0005] Specifically, the present invention is applicable to a process for preparing cement raw meal fired by solar concentrating, comprising the following steps:

[0006] 1) Check the chemical composition of the raw materials and calculate the ingredients according to the designed three-rate value and Co3O4+MnO2 content.

[0007] 2) Mix the raw materials according to the mass ratio, add appropriate amount of grinding aid and perform ball milling to obtain powder.

[0008] 3) Mix the powder and isopropyl alcohol thoroughly and dry.

[0009] The invention takes Portland cement as the design basis, and homogenizes the raw materials through physical mixing, ball milling and isopropyl alcohol, so that the two metal oxides Co3O4 and MnO2 are evenly dispersed in the raw material and the effective addition amount can be increased, thereby obtaining a cement raw material suitable for solar concentrated firing and with extremely strong absorption capacity in a wide ultraviolet, visible and infrared spectrum range.

[0010] Preferably, the raw materials in step 1) are composed of calcareous raw materials, clay raw materials, steel slag, cobalt-manganese slag and nickel-containing waste slag.

[0011] Preferably, the calcareous raw material is limestone.

[0012] Preferably, the clay raw material is sandstone.

[0013] 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.

[0014] The three rates of cement raw meal 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 conducted 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 meal in the selected band, as well as the light-heat conversion capacity, and finally selected the above three rates.

[0015] Preferably, in step 1), the content of Co3O4+MnO2 is 0.75-3%.

[0016] The acquisition of cement clinker undergoes three major physical and chemical changes, mainly the decomposition of carbonates, solid-phase reaction, and sintering of liquid phase and clinker. The large-scale production of its main mineral tricalcium silicate marks the burning of cement clinker. Steel slag and cobalt-manganese slag are waste materials generated during the industrial production process. They contain the main oxides SiO2, CaO and Al2O3 in cement raw materials and some difficult-to-extract Mn and Co metal elements. 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 during the low-temperature irradiation stage, but also undergo mutations under high-temperature conditions, playing the role of mineralizers / fluxing agents in the sintering process of silicate cement clinker, thereby promoting the formation of a liquid phase, which is beneficial to improving burnability. In addition, the combined use of the two has a small effect on the mineral content and development of the synthesized clinker during the high-temperature stage, but the improvement in the overall light absorption and photothermal conversion capacity of the raw materials is very obvious. Therefore, it is suitable for cement raw materials to be fired in solar 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.

[0017] Preferably, in step 3), the mass ratio of the powder to isopropyl alcohol is 1:(0.9-1.5).

[0018] Preferably, in step 3), the drying temperature is 55-70° C. and the drying time is 48-188 hours.

[0019] The present invention also relates to cement raw material suitable for solar concentrated firing, which is specifically prepared by the above-mentioned preparation process.

[0020] The present invention also relates to cement clinker, which is specifically made by burning the above-mentioned cement raw material in a solar concentrating device.

[0021] The present invention also relates to cement, specifically, cement 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.

[0022] The present invention also relates to the application of the cement in the production of building materials.

[0023] The present invention has the following technical advantages:

[0024] 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.

[0025] 2. The present invention can utilize industrial waste residue and renewable energy to burn clinker, which has good energy-saving effect.

[0026] 3. The clinker prepared by the present invention is of qualified quality and the cement strength meets the standard requirements. DETAILED DESCRIPTION

[0027] In order to characterize the technical effect of the present invention, cement raw materials were prepared and tested for sunlight weighted absorption performance and room temperature photothermal 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 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 of cement was prepared, and the cement slurry was formed and cured for 28 days before the compressive strength test was carried out. Among them, 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 taken and pressed under a pressure of 10MPa to obtain a disc with a diameter of 2.6cm. The photothermal conversion capacity test condition was a light power of 100W / m 2The test time is 30 minutes; the recording time interval is every 5 seconds from 0 to 1 minute, every 10 seconds from 2 to 5 minutes, every 30 seconds from 6 to 20 minutes, and every 2 minutes from 21 to 30 minutes.

[0028] Example 1, cement raw material, the preparation process steps are:

[0029] 1) Detect the chemical composition of limestone, sandstone, steel slag, cobalt-manganese slag and nickel-containing waste slag, and calculate the ingredients based on the design three-rate values IM=1.50, KH=0.90, SM=2.49 and Co3O4+MnO2 content of 0.75%.

[0030] 2) Mix the raw materials according to the mass ratio, add appropriate amount of grinding aid and perform ball milling to obtain powder.

[0031] 3) Thoroughly mix the powder and isopropyl alcohol in a mass ratio of 1:1 and dry.

[0032] After testing, the weighted absorption ratio of the 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 the clinker is 1.4%, and the 3d compressive strength of the cement slurry specimen is 24.2MPa, the 7d compressive strength is 36.7MPa, and the 28d compressive strength is 51.9MPa.

[0033] Example 2, cement raw material, the preparation process steps are:

[0034] 1) Test the chemical composition of limestone, sandstone, steel slag, cobalt-manganese slag and nickel-containing waste slag, and calculate the ingredients based on the design three-rate values IM=1.51, KH=0.89, SM=2.47 and Co3O4+MnO2 content of 1.5%.

[0035] 2) Mix the raw materials according to the mass ratio, add appropriate amount of grinding aid and perform ball milling to obtain powder.

[0036] 3) Thoroughly mix the powder and isopropyl alcohol in a mass ratio of 1:1.2 and dry.

[0037] After testing, the weighted absorption ratio of the 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 clinker f-CaO content is 0.9%, and the 3d compressive strength of the cement slurry specimen is 26.5MPa, the 7d compressive strength is 40.2MPa, and the 28d compressive strength is 55.1MPa.

[0038] Example 3, cement raw material, the preparation process steps are:

[0039] 1) Detect the chemical composition of limestone, sandstone, steel slag, cobalt-manganese slag and nickel-containing waste slag, and calculate the ingredients based on the design three-rate values IM=1.51, KH=0.90, SM=2.5 and Co3O4+MnO2 content of 3%.

[0040] 2) Mix the raw materials according to the mass ratio, add appropriate amount of grinding aid and perform ball milling to obtain powder.

[0041] 3) Thoroughly mix the powder and isopropyl alcohol in a mass ratio of 1:1.5 and dry.

[0042] After testing, the weighted absorption ratio of the cement raw material spectrum is 35.6%, the maximum temperature during photothermal conversion heating is 79.2℃, the maximum temperature difference is 49.0℃, the clinker f-CaO content is 0.6%, and the 3d compressive strength of the cement slurry specimen is 26.7MPa, the 7d compressive strength is 39.8MPa, and the 28d compressive strength is 56.4MPa.

[0043] Blank example, cement raw material, preparation process steps are:

[0044] 1) Test the chemical composition of limestone, sandstone and steel slag, and calculate the proportioning according to the design three-rate values IM=1.50, KH=0.90 and SM=2.47.

[0045] 2) Mix the raw materials according to the mass ratio, add appropriate amount of grinding aid and perform ball milling to obtain powder.

[0046] 3) Thoroughly mix the powder and isopropyl alcohol in a mass ratio of 1:1 and dry.

[0047] After testing, the weighted absorption ratio of the 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 the clinker is 1.9%, and the 3d compressive strength of the cement slurry specimen is 21.3MPa, the 7d compressive strength is 34.1MPa, and the 28d compressive strength is 48.9MPa.

[0048] Comparative Example 1, cement raw material, the preparation process steps are:

[0049] 1) Detect the chemical composition of limestone, sandstone, steel slag, cobalt-manganese slag and nickel-containing waste slag, and calculate the ingredients based on the design three-rate values IM=1.51, KH=0.90, SM=2.5 and Co3O4+MnO2 content of 3%.

[0050] 2) Mix the raw materials according to the mass ratio, add appropriate amount of grinding aid and ball mill to obtain.

[0051] After testing, the weighted absorption ratio of the cement raw material spectrum is 17.2%, the maximum temperature during photothermal conversion heating is 70.5℃, the maximum temperature difference is 41.6℃, the f-CaO content of the clinker is 1.6%, and the 3d compressive strength of the cement slurry specimen is 22.9MPa, the 7d compressive strength is 35.2MPa, and the 28d compressive strength is 49.6MPa.

[0052] Comparative Example 2, cement raw material, the preparation process steps are:

[0053] 1) Test the chemical composition of limestone, sandstone, steel slag, cobalt-manganese slag and nickel-containing waste slag, and calculate the ingredients based on the design three-rate values IM=1.38, KH=0.96, SM=2.0 and Co3O4+MnO2 content of 3%.

[0054] 2) Mix the raw materials according to the mass ratio, add appropriate amount of grinding aid and perform ball milling to obtain powder.

[0055] 3) Thoroughly mix the powder and isopropyl alcohol in a mass ratio of 1:1.5 and dry.

[0056] After testing, the weighted absorption ratio of the cement raw material spectrum is 10.3%, the maximum temperature during photothermal conversion heating is 69.3℃, the maximum temperature difference is 41.5℃, the clinker f-CaO content is 2.3%, and the 3d compressive strength of the cement slurry specimen is 19.8MPa, the 7d compressive strength is 32.7MPa, and the 28d compressive strength is 45.0MPa.

[0057] 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 above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A process for preparing cement raw meal 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 values and Co3O4+MnO2 content. The three-rate values are IM=1.50±0.03, KH=0.90±0.03, SM=2.47±0.03, and the Co3O4+MnO2 content is 0.75-3%. The content of Co3O4 and MnO2 is not 0. 2) Mix the raw materials according to the mass ratio, add appropriate amount of grinding aid and perform ball milling to obtain powder. 3) The powder and isopropyl alcohol are fully mixed and dried to obtain the product, wherein the mass ratio of the powder to the isopropyl alcohol is 1:(0.9-1.5).

2. The process for preparing cement raw material suitable for solar concentrated firing according to claim 1, characterized in that: The raw materials in step 1) are composed of calcareous 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. A cement raw material suitable for solar concentrated firing, characterized in that: The invention is prepared by the preparation process according to any one of claims 1 to 4.

6. A cement clinker, characterized in that: The cement raw material according to claim 5 is fired in a solar concentrating device.

7. A cement characterized by: The cement clinker according to claim 6 and gypsum are mixed and ball-milled to prepare the mixture.