Cement raw meal prepared using stone slag and stone powder and method for preparing cement clinker using the same

Abstract

The application provides a cement raw material prepared from stone slag and stone powder and a method for preparing cement clinker by using the same. The cement raw material is composed of the following raw materials in percentage by weight: limestone 70-80%, stone slag and stone powder 10-15%, iron ore dressing powder 8-11%, and coal-fired furnace slag 2-4%. The method for preparing cement clinker comprises the following steps: mixing the raw materials in proportion, grinding the mixture to obtain the cement raw material, and storing the raw material in a homogenizing warehouse; feeding the raw material powder into a preheater by a conveying device for pre-decomposition to obtain semi-clinker; and feeding the semi-clinker into a rotary kiln, performing high-temperature calcination in the rotary kiln, and then feeding the semi-clinker into a grate cooler for rapid cooling to obtain the cement clinker. The application uses dolomite stone slag and stone powder as the cement raw material, which can reduce the cost of cement production, ensure the quality of the clinker, and is beneficial to the comprehensive utilization of mineral resources and the extension of the service life of the mine.

Description

Technical Field

[0001] This invention relates to the field of cement production, and more particularly to a cement raw meal made from stone chips and stone powder and a method for preparing cement clinker using the same. Background Technology

[0002] Cement is a crucial raw material for the national economy and occupies a primary position in building materials applications. Limestone is a major calcareous raw material for cement production; however, with continuous mining, limestone reserves are dwindling, and its quality is deteriorating, with high alkali content affecting the quality of cement clinker and the performance of cement. To ensure clinker quality and improve cement performance, many cement companies with conventional alkali-limestone mines have had to purchase expensive, low-alkali limestone from external sources to use in combination with their own limestone. While this ensures cement quality, it also increases production costs.

[0003] Due to its high magnesium content, dolomite has not been effectively used in cement raw material production. Stone slag and stone powder are powders produced during the processing of dolomite mineral resources. They are waste residues, characterized by high calcium, high magnesium, and low alkali. If this part of the resource can be rationally utilized, it can not only reduce the production cost of cement, but also promote the comprehensive utilization of mineral resources. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention provides a method for preparing cement raw meal using dolomite slag and stone powder, and for preparing cement clinker using the same. Using dolomite slag and stone powder in cement production can reduce the cost of cement production, ensure the quality of cement clinker, and facilitate the comprehensive utilization of mineral resources, thereby extending the service life of mines.

[0005] In a first aspect, the present invention provides a cement raw meal made from stone chips and stone powder, which is composed of the following raw materials by weight percentage:

[0006] Limestone: 70%~80%

[0007] Stone chips and stone powder: 10%~15%

[0008] Iron ore powder: 8%~11%

[0009] Coal-fired furnace slag: 2%~4%.

[0010] Furthermore, the limestone comprises the following components by weight percentage: 44%~48% CaO, 6%~8% SiO2, 1.2%~2.3% Al2O3, 0.5%~1.0% Fe2O3, 1.0%~2.0% MgO, and 0.65%~0.85% R2O, wherein R2O is the alkali content.

[0011] Furthermore, the stone slag and stone powder include the following components by weight percentage: CaO 42%~44%, SiO2 3%~5%, Al2O3 1.0%~2.5%, Fe2O3 0.5%~0.7%, MgO 10%~15%, and R2O 0.4%~0.6%.

[0012] Furthermore, the iron ore powder comprises the following components by weight percentage: 3%~5% CaO, 60%~70% SiO2, 1.5%~2.5% Al2O3, 10%~15% Fe2O3, 1.5%~3.0% MgO, and 0.9%~1.0% R2O.

[0013] Furthermore, the coal-fired slag includes the following components by weight percentage: CaO 4.0%~6.0%, SiO2 30%~40%, Al2O3 25%~30%, Fe2O3 4.0%~6.0%, MgO 0.5%~2.0%, and R2O 0.7%~1.3%.

[0014] Furthermore, the stone slag and stone powder are dolomite-like powders with a particle size of 0-5mm, which are mining and beneficiation waste residues.

[0015] Secondly, the present invention also provides a method for preparing cement clinker using the aforementioned cement raw meal, comprising the following steps:

[0016] S1. Mix the raw materials in proportion, grind them after mixing to obtain cement raw meal, and place the raw meal in a homogenization silo for homogenization and storage.

[0017] S2. The homogenized raw meal powder in S1 is fed into a preheater for pre-decomposition through a conveying device to obtain semi-cooked meal.

[0018] S3. The pre-decomposed semi-clinker from S2 is fed into a rotary kiln. After being calcined at high temperature in the rotary kiln, it is rapidly cooled in a grate cooler and crushed to obtain cement clinker.

[0019] Preferably, the temperature in S2 is 850~920℃ and the time is 40~60s; the calcination temperature in S3 is 1350~1450℃ and the calcination time is 30~40min.

[0020] The cement clinker was subjected to performance testing, and all indicators of the cement clinker met the national standards and satisfied the requirements for use.

[0021] The KH of the cement clinker is between 0.88 and 0.92, SM is between 2.45 and 2.65, IM is between 1.45 and 1.65, R2O content is between 0.95 and 1.15%, MgO content does not exceed 5.0%, and the 28-day compressive strength meets the national standard.

[0022] Wherein, KH is the lime saturation coefficient, which indicates the degree to which silica in cement clinker is saturated by calcium oxide to form tricalcium silicate.

[0023] SM stands for silica ratio, which represents the ratio of silica content to aluminum oxide and ferric oxide content in cement clinker.

[0024] IM stands for aluminum oxide ratio, which represents the ratio of aluminum oxide content to ferric oxide content in cement clinker.

[0025] The present invention has the following beneficial effects:

[0026] This invention provides a cement raw meal made from stone slag and stone powder and a method for preparing cement clinker using the same. Using dolomite-type stone slag and stone powder as cement raw meal can reduce the cost of cement production, ensure the quality of clinker, and at the same time facilitate the comprehensive utilization of mineral resources and extend the service life of mines. Detailed Implementation

[0027] To fully understand the purpose, features and effects of the present invention, the present invention will be described in detail through the following specific embodiments, but the present invention is not limited thereto.

[0028] Raw material source:

[0029] The limestone was produced by the company's own mine.

[0030] Stone slag and stone powder are waste residues from the mining and beneficiation of dolomite.

[0031] Iron ore powder is the tailings after the beneficiation of iron ore in iron mines.

[0032] Coal-fired furnace slag is the slag produced in power plants after the raw coal is burned to generate electricity.

[0033] This invention provides a method for preparing cement raw meal from stone slag and stone powder and for preparing cement clinker therefrom. The cement raw meal comprises the following raw materials by weight percentage: limestone 70%~80%, stone slag and stone powder 10%~15%, iron ore powder 8%~11%, and coal slag 2%~4%. Cement clinker is produced according to the following steps:

[0034] S1. Mix the raw materials in proportion, grind them after mixing to obtain cement raw meal, and place the raw meal in a homogenization silo for homogenization and storage.

[0035] S2. The homogenized raw meal powder in S1 is fed into a preheater through a conveying device for pre-decomposition to obtain semi-clinker at a temperature of 850~920℃ for 40~60s.

[0036] S3. The pre-decomposed semi-clinker from S2 is fed into a rotary kiln and calcined at 1350~1450℃ for 30~40 minutes. Then it is rapidly cooled in a grate cooler and crushed to obtain cement clinker.

[0037] The limestone comprises the following components by weight percentage: CaO 44%~48%, SiO2 6%~8%, Al2O3 1.2%~2.3%, Fe2O3 0.5%~1.0%, MgO 1.0%~2.0%, and R2O 0.65%~0.85%. R2O represents the alkali content.

[0038] Stone slag and stone powder comprise the following components by weight percentage: CaO 42%~44%, SiO2 3%~5%, Al2O3 1.0%~2.5%, Fe2O3 0.5%~0.7%, MgO 10%~15%, and R2O 0.4%~0.6%. Stone slag and stone powder are dolomite-like powders with a particle size of 0~5mm, and are mining and beneficiation waste.

[0039] Iron ore powder comprises the following components by weight percentage: CaO 3%~5%, SiO2 60%~70%, Al2O3 1.5%~2.5%, Fe2O3 10%~15%, MgO 1.5%~3.0%, and R2O 0.9%~1.0%.

[0040] Coal-fired furnace slag includes the following components by weight percentage: CaO 4.0%~6.0%, SiO2 30%~40%, Al2O3 25%~30%, Fe2O3 4.0%~6.0%, MgO 0.5%~2.0%, and R2O 0.7%~1.3%.

[0041] The percentages of each component in the above raw materials are parameters after homogenization. Example 1

[0042] This embodiment provides a method for preparing cement raw meal using stone slag and stone powder and for preparing cement clinker using the same. The cement raw meal includes the following raw materials by weight percentage: limestone: 82.5%, stone slag and stone powder: 5%, iron ore powder: 9.5%, and coal slag: 3.0%. The chemical composition of each raw material is shown in Table 1.

[0043] Table 1 Chemical composition of each raw material in Example 1

[0044]

[0045] The method for preparing cement clinker using the aforementioned cement raw meal includes the following steps:

[0046] S1. Mix the raw materials in proportion, grind them to obtain cement raw meal, and place the raw meal in a homogenization silo for homogenization and storage.

[0047] S2. The homogenized raw meal powder from S1 is fed into a preheater via a conveying device. In the preheater, it undergoes pre-decomposition at a temperature of up to 880°C for 60 seconds to obtain semi-cooked meal.

[0048] S3. The pre-decomposed semi-clinker from S2 is fed into a rotary kiln. After being calcined at a high temperature of 1450℃ for 40 minutes in the rotary kiln, it is rapidly cooled in a grate cooler and crushed to obtain cement clinker.

[0049] The obtained cement clinker has a KH content of 0.89, a SM content of 2.60, an IM content of 1.60, an R2O content of 1.10%, an MgO content of 3.1%, and a 28-day compressive strength of 53 MPa.

[0050] Examples 2-6

[0051] The chemical composition of each raw material in the cement raw meal in Examples 2-6 is the same as that in Example 1, and the preparation method of the cement clinker is the same as that in Example 1. The composition of the cement raw meal in Examples 2-6 is shown in Table 2, and the performance indicators of the obtained cement clinker are shown in Table 3.

[0052] The cement raw meal in Example 6 does not contain stone chips or stone powder, and serves as a benchmark for comparison with other examples.

[0053] Table 2 Cement raw meal composition of Examples 1-6

[0054]

[0055] Table 3 Performance Indicators of Cement Clinker in Examples 1-6

[0056]

[0057] Tables 2 and 3 show that using dolomite-type stone chips and powder as cement raw materials produces cement with performance that meets national standards. The cement performance is optimal when the stone chip and powder content is 10-15%, the R2O content in the clinker does not exceed 1.10%, the MgO content does not exceed 5%, and the 28-day compressive strength is greater than 53.5 MPa. Comparative Example 1

[0058] The cement raw materials and cement clinker were produced using purchased low-alkali limestone in a comparative proportion. The cement raw materials consisted of the following raw materials by weight percentage: limestone: 81%, purchased low-alkali limestone: 6%, iron ore powder: 9.5%, and coal slag: 3.5%.

[0059] The chemical composition of the purchased low-alkali limestone is shown in Table 4. The chemical composition of the other raw materials is the same as that in Example 1.

[0060] Table 4 Chemical composition of purchased low-alkali limestone

[0061]

[0062] The preparation method of cement clinker is the same as in Example 1, and the performance indicators of the obtained cement clinker are shown in Table 5.

[0063] Table 5 Performance indicators of cement clinker in Comparative Example 1

[0064]

[0065] As shown in Tables 3 and 5, the 28-day compressive strength of cement clinker made with an appropriate amount of dolomite-type slag powder is superior to that made with purchased low-alkali limestone. Furthermore, the MgO content of the cement clinker made with dolomite-type slag powder is higher than that made with purchased low-alkali limestone. Increasing the MgO content in the clinker leads to an increase in the liquid phase content and a decrease in liquid phase viscosity, resulting in stable use in raw meal batching and significantly improving the burnability of the raw meal. Since MgO has a micro-expansion characteristic in concrete, increasing the MgO content also helps reduce the drying shrinkage of concrete in the later stages.

[0066] The cost of cement raw meal using purchased low-alkali limestone is approximately 37 yuan / ton, while the cost of cement raw meal using stone chips and powder is no more than 35.5 yuan / ton. This represents a cost saving of at least 1.5 yuan / ton in cement raw meal production. Based on an annual raw meal production of 2 million tons, this translates to a cost reduction of at least 3 million yuan per year in cement clinker production.

[0067] This invention uses dolomite-type slag and stone powder as cement raw material, which can reduce the cost of cement production, while also facilitating the comprehensive utilization of mineral resources and extending the service life of mines.

[0068] Finally, it should be noted that the above-listed embodiments are merely preferred embodiments of the present invention. Of course, those skilled in the art can make modifications and variations to the present invention. If such modifications and variations fall within the scope of the claims of the present invention and their equivalents, they should be considered as being within the protection scope of the present invention.

Claims

1. A cement raw material made from stone chips and stone powder, characterized in that, It consists of the following raw materials by weight percentage: Limestone: 70%~80%, including the following components by weight percentage: CaO 44%~48%, SiO2 6%~8%, Al2O3 1.2%~2.3%, Fe2O3 0.5%~1.0%, MgO 1.0%~2.0%, R2O 0.65%~0.85%; Stone slag and stone powder: 10%~15%, including the following components by weight percentage: CaO 42%~44%, SiO2 3%~5%, Al2O3 1.0%~2.5%, Fe2O3 0.5%~0.7%, MgO 10%~15%, R2O 0.4%~0.6%; stone slag and stone powder are dolomite-like powders with a particle size of 0~5mm, which are mining and beneficiation waste residues; Iron ore powder: 8%~11%, including the following components by weight percentage: CaO 3%~5%, SiO2 60%~70%, Al2O3 1.5%~2.5%, Fe2O3 10%~15%, MgO 1.5%~3.0%, R2O 0.9%~1.0%; Coal-fired furnace slag: 2%~4%, including the following components by weight percentage: CaO 4.0%~6.0%, SiO2 30%~40%, Al2O3 25%~30%, Fe2O3 4.0%~6.0%, MgO 0.5%~2.0%, R2O 0.7%~1.3%.

2. The method for preparing cement clinker using cement raw meal obtained from stone chips and stone powder as described in claim 1, characterized in that, Includes the following steps: S1. Mix the raw materials in proportion, grind them to obtain cement raw meal, and place the raw meal in a homogenization silo for homogenization and storage. S2. The homogenized raw meal powder in S1 is fed into a preheater for pre-decomposition through a conveying device to obtain semi-cooked meal. S3. The pre-decomposed semi-clinker from S2 is fed into a rotary kiln. After being calcined at high temperature in the rotary kiln, it is rapidly cooled in a grate cooler and crushed to obtain cement clinker.

3. The method according to claim 2, characterized in that, The temperature in S2 is 850~920℃ and the time is 40~60s; the calcination temperature in S3 is 1350~1450℃ and the calcination time is 30~40min.

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