CN108314338B - Low-alkali portland cement clinker and preparation method thereof - Google Patents
Low-alkali portland cement clinker and preparation method thereof Download PDFInfo
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- CN108314338B CN108314338B CN201810464325.3A CN201810464325A CN108314338B CN 108314338 B CN108314338 B CN 108314338B CN 201810464325 A CN201810464325 A CN 201810464325A CN 108314338 B CN108314338 B CN 108314338B
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- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B7/00—Hydraulic cements
- C04B7/24—Cements from oil shales, residues or waste other than slag
- C04B7/26—Cements from oil shales, residues or waste other than slag from raw materials containing flue dust, i.e. fly ash
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- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
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- C04B7/00—Hydraulic cements
- C04B7/02—Portland cement
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- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
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- C04B7/22—Iron ore cements ; Iron rich cements, e.g. Ferrari cements, Kühl cements
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- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
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- C04B7/36—Manufacture of hydraulic cements in general
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Abstract
The invention belongs to the technical field of production of portland cement clinker, and particularly relates to low-alkali portland cement clinker and a preparation method thereof. A low alkali portland cement clinker characterized by: the limestone-sand composite material is prepared by grinding, uniformly mixing, calcining at high temperature and cooling matched limestone, iron ore, shale, wet fly ash and siltstone with different grades serving as raw materials. The low-alkali silicate clinker prepared by the method has low alkali content, low water demand, high strength and high utilization rate of low-grade limestone.
Description
Technical Field
The invention relates to the technical field of production of portland cement clinker, and particularly relates to low-alkali portland cement clinker and a preparation method thereof.
Background
The low-alkali cement is a main cementing material which is generally concerned by the current building engineering industry and can inhibit alkali-aggregate reaction (or called alkali-aggregate reaction) and enhance the engineering durability. In general, cement having an alkali content of not more than 0.60% by weight in cement is called low alkali cement.
The low-alkali cement has low alkali content, so that the problems of large shrinkage, easy cracking and the like of cement products caused by overhigh early hydration speed of cement cannot occur, and meanwhile, the low-alkali cement has low alkali content, so that the chemical reaction risk between alkali and aggregate is greatly reduced in some concrete buildings and members, and the occurrence probability of the problem of structural damage caused by expansion cracking of the buildings and the members caused by alkali-aggregate reaction is also greatly reduced.
The low-alkali cement has excellent durability, so that the low-alkali cement is widely applied to a series of key projects such as bridges, railways, large buildings and the like, the grade of the cement is higher, the strength grade is generally not lower than 42.5 grade, the doping amount of the clinker in the low-alkali cement is generally higher, and the key point for controlling the alkali content of the low-alkali cement is to control the alkali content of the clinker. In practice, due to the quality of limestone, or the need to use more siliceous correcting materials (such as siltstone and silica) and aluminous correcting materials (such as wet coal ash) with relatively low alkali content to replace part of high-alkali aluminosilicous materials (such as shale), the mixing amount of siliceous materials with poor grindability and burnability is high, the grindability and the burnability of raw materials are difficult to ensure, and finally, the low-alkali portland cement clinker is difficult to realize continuous production.
Therefore, how to fully and effectively match limestone with different grades, properly use aluminum correction materials and replace part of high-alkali alumino-silicate materials (shale) with poor grindability and burnability to produce high-quality low-alkali portland cement clinker has important significance for comprehensively utilizing mine resources, reducing production cost and meeting the market demand of high-end cement products of key projects.
Disclosure of Invention
The invention aims to provide a method for producing low-alkali portland cement clinker by utilizing different grades of limestone and a proper amount of siliceous correction material siltstone with poor grindability and burnability.
In order to achieve the purpose, the technical scheme of the invention is as follows:
the low-alkali portland cement clinker is prepared by grinding, uniformly mixing, calcining at high temperature and cooling matched raw materials of limestone, iron ore, shale, wet fly ash and siltstone with different grades.
Preferably, the alkali content R of said shale2O is more than or equal to 2.00 percent, and the alkali content of the iron ore, the wet fly ash and the siltstone is less than 2.00 percent.
Preferably, the limestone with different grades is high-alkali high-aluminum low-calcium limestone and low-alkali high-silicon high-calcium limestone, wherein the alkali content R of the high-alkali high-aluminum low-calcium limestone20.20 to 0.40 percent of O and Al content of aluminum oxide2O31.50 to 3.00 percent, the content of CaO is less than 48.00 percent, and the alkali content R of the low-alkali high-silicon high-calcium limestone2O is 0.05-0.20%, and the content of silicon dioxide SiO is2Not less than 7.00 percent of oxygenThe CaO content of the calcium oxide is more than or equal to 48.00 percent.
Preferably, the low alkali portland cement clinker alkali content R2O is less than or equal to 0.60wt%, and the control range of the three-rate value is as follows: saturation ratio KH is 0.930 ± 0.020, silicic acid SM is 2.65 ± 0.10, and aluminum yield IM is 1.40 ± 0.10.
Preferably, the method for manufacturing the low alkali portland cement clinker comprises the following steps:
1) determining the limestone matching proportion range: according to different limestone grades, determining a limestone matching proportion limit value to ensure the alkali content R of subsequently prepared clinker2O is less than or equal to 0.60wt%, and the wet base mixing ratio of the siltstone with poor grindability and burnability in the raw material is less than or equal to 3.0 wt%;
2) pretreatment of raw materials: crushing or screening limestone, iron ore, shale, wet fly ash and siltstone, and matching and pre-homogenizing limestone with different grades within a matching limit range;
6) raw material proportioning and grinding: according to the matching conditions of limestone with different grades, calculating a blending scheme of limestone, iron ore, shale, wet fly ash and siltstone by mass, uniformly mixing the limestone, iron ore, shale, wet fly ash and siltstone in proportion, feeding the mixture into a grinding system with a drying function for grinding and screening, controlling the water content of a ground finished product to be less than or equal to 1.0wt%, controlling the screen allowance of a 80-micrometer square-hole screen to be 20wt +/-2 wt%, and controlling the screen allowance of a 0.2-millimeter square-hole screen to be less than or equal to 2.0wt%, and obtaining dry powdery raw material;
7) preparing clinker: feeding the mixed and homogenized dry powdery raw materials into a suspension preheater and a decomposing furnace for preheating and decomposing, then feeding the raw materials into a cement rotary kiln, carrying out high-temperature calcination at 1350-1450 ℃ to obtain partially molten materials with 24-27% of liquid phase amount, and controlling the pressure under a section of grate to be 5600-6200 Pa to ensure that the molten materials are fully cooled by a high-pressure blower on the grate cooler to obtain portland cement clinker with the kiln discharge temperature of 60-100 ℃;
8) determining the content of clinker alkali and adjusting the batching scheme: if the alkali content R is2If O is more than 0.60wt%, the target value of the clinker alkali content is set to be lower, and wet fly ash and siltstone are used for further replacing part of high alkali shale to adjustPreparing the blending scheme, and producing the low-alkali portland cement clinker according to the step 3) and the step 4).
Preferably, the limestone matching proportion range determined in the step 1) is obtained by solving and calculating through nonlinear programming according to chemical components of limestone, iron ore, shale, wet fly ash and siltstone of different grades, and a calorific value, an ash content, an ash chemical component and a heat consumption value of clinker of the ton in the kiln, so that the clinker alkali content R in the raw material matching scheme is achieved2O is less than or equal to 0.60wt percent, and the wet base mixing ratio of the siltstone with poor grindability and easy burning property in the raw meal is less than or equal to 3.0wt percent.
Preferably, the blending scheme of the iron ore, the shale, the wet fly ash and the siltstone in the step 3) is determined according to the matching situation of the limestone, wherein the two materials of the wet fly ash and the siltstone can be blended into only one material, or the shale with higher alkali content in the substitution part may be blended into the two materials simultaneously.
The invention has the beneficial effects that:
1. according to the chemical components of limestone, iron ore, shale, wet fly ash and siltstone of different grades, the heat value, ash content, ash chemical component and the heat consumption value of the clinker of the ton in the kiln, the matching proportion range of the limestone is rapidly and accurately calculated by solving through nonlinear programming, so that the content R of the clinker alkali can be increased2O is less than or equal to 0.60wt%, and the wet base doping amount of the siltstone with poor grindability and burnability in the raw material is less than or equal to 3.0wt%, so that the improvement of the bench production of the raw material and the reduction of the power consumption are facilitated, and the good burnability of the clinker is ensured, wherein the bench production of the raw material is increased by more than 8%, and the f-CaO content of the clinker is reduced by more than 0.20%.
2. In the limestone matching proportion range, mine resources can be flexibly and fully utilized to produce the low-alkali portland cement clinker according to the mine production condition, even if the alkali content of the clinker slightly exceeds 0.60wt%, part of wet fly ash and siltstone with relatively low alkali content can be utilized to replace high-alkali shale, the clinker quality is ensured, the production cost is saved, and the low-grade limestone can be fully utilized to realize the maximum utilization of resources.
3. The produced low-alkali portland cement clinker has good calcination effect and low alkali content, the standard consistency of the clinker can be reduced to below 24.0 percent, the 3d compressive strength is increased by more than 1.0MPa, and the 28d compressive strength is increased by more than 2.0 MPa.
4. The produced low-alkali portland cement clinker provides favorable guarantee for producing low-alkali cement and cement products to enter high-end markets, and the produced low-alkali ordinary portland cement has low standard consistency, high strength and good durability, is widely applied to various major projects, is consistently favored by customers, and effectively improves the market share and brand image of the products.
Detailed Description
The technical solution of the present invention is further illustrated by the following examples.
Example 1
The low-alkali portland cement clinker is produced on a 2500t clinker/d novel dry production line by using a preparation method of the low-alkali portland cement clinker, wherein the control range of three rate values of the clinker is as follows: saturation ratio KH is 0.930 ± 0.020, silicic acid SM is 2.65 ± 0.10, and aluminum yield IM is 1.40 ± 0.10. The specific operation steps are as follows:
1) determining the limestone matching proportion range: according to the chemical components of limestone A and limestone B, iron ore, shale, wet fly ash and siltstone of different grades, the heat value, ash content and ash chemical component of coal powder and the heat consumption value of clinker production unit on a kiln of 3429kJ/kg, when the proportion of low-grade limestone A in the total amount of limestone is less than or equal to 30.29 percent and the alkali content R of clinker is obtained by solving and calculating through nonlinear programming2O is less than or equal to 0.60wt%, and the wet base mixing ratio of the siltstone with poor grindability and burnability in the raw meal is less than or equal to 3.0 wt%;
2) pretreatment of raw materials: crushing or screening limestone, iron ore, shale, wet fly ash and siltstone, and matching and pre-homogenizing limestone with different grades within a matching limit range;
3) raw material proportioning and grinding: according to the matching conditions of limestone with different grades, calculating a blending scheme of limestone, iron ore, shale, wet fly ash and siltstone by mass, uniformly mixing the limestone, iron ore, shale, wet fly ash and siltstone in proportion, feeding the mixture into a grinding system with a drying function for grinding and screening, controlling the water content of a ground finished product to be less than or equal to 1.0wt%, controlling the screen allowance of a 80-micrometer square-hole screen to be 20wt +/-2 wt%, and controlling the screen allowance of a 0.2-millimeter square-hole screen to be less than or equal to 2.0wt%, and obtaining dry powdery raw material;
4) preparing clinker: feeding the dry powdery raw materials mixed and homogenized in the step 3) into a suspension preheater and a decomposing furnace for preheating and decomposing, then feeding into a cement rotary kiln, carrying out high-temperature calcination at 1350-1450 ℃ to obtain a partially molten material with 24-27% of liquid phase amount, and controlling the pressure under a section of grate to be 5600-6200 Pa to fully cool the molten material on a grate cooler by a high-pressure blower so as to prepare the portland cement clinker with the kiln outlet temperature of 60-100 ℃;
5) determining the content of clinker alkali and adjusting the batching scheme: if the alkali content R is2And if the O is more than 0.60wt%, setting the target value of the clinker alkali content to be lower, further replacing part of high-alkali shale with wet fly ash and siltstone to adjust the batching scheme, and then producing the low-alkali portland cement clinker according to the steps 3) and 4).
In the clinker preparation process, the decomposition rate of raw materials entering a rotary kiln is 90-95%, the f-CaO content of clinker is 0.50-1.20%, and the vertical rise weight of clinker is 1270-1350 g/L by controlling the outlet temperature of a decomposing furnace at 865 +/-5 ℃ and the secondary air temperature at 1150 +/-50 ℃ at the kiln head.
The chemical compositions of limestone a and limestone B, iron ore, shale, wet fly ash and siltstone of different grades are shown in table 1:
TABLE 1 raw material chemistry
The results of the characteristics of the coal dust are shown in table 2:
TABLE 2 coal dust Properties
Description of the drawings: the calorific value of the pulverized coal in table 2 is the lower calorific value of the pulverized coal as an analysis base.
In the step 2), the limestone A is matched with the limestone B according to the proportion of 10 percent, 25 percent and 40 percent of the total amount of the limestone to produce the portland cement clinker, the limestone A accounts for 10 percent and 25 percent of the total amount of the limestone within the range of the matching proportion and is used for producing the low-alkali portland cement clinker, and the limestone A accounts for 40 percent of the total amount of the limestone not within the range of the matching proportion and is used for producing a portland cement clinker comparison sample.
When the limestone A is respectively matched with the limestone B according to the proportion of 10%, 25% and 40% of the total amount of the limestone in the step 3), 4 raw material proportioning schemes are provided correspondingly, as shown in tables 3-1 to 3-4, the chemical components of the limestone in the tables are weight average values after the limestone A and the limestone B are matched according to the corresponding proportion, wherein when the limestone A is 40% of the total amount of the limestone, the alkali content R of clinker can not be met simultaneously2O is less than or equal to 0.60wt%, and the wet base mixing ratio of the siltstone with poor grindability and burnability in the raw material is less than or equal to 3.0wt%, two raw material proportioning schemes are correspondingly designed, and tables 3-3 are to meet the clinker alkali content R2Scheme 3 with O less than or equal to 0.60wt%, and tables 3-4 are scheme 4 with the wet base mixing ratio of siltstone in the raw meal less than or equal to 3.0wt%, which satisfies the requirements of poor grindability and burnability.
Table 3-1 ingredient scheme 1 when limestone a accounts for 10% of the total limestone amount
Description of the drawings: in Table 3-1, the chemical components of the raw meal are weighted average values of the chemical components of limestone, shale, siltstone, wet fly ash and iron ore; burning the chemical components of the raw material, namely the chemical components of the raw material are multiplied by 100/(100-LOSS); the dry-basis proportion of coal ash is equal to the ash content of coal powder multiplied by the calorific value of coal powder/heat consumption of clinker production unit; burning raw material as 100-coal ash dry basis proportion; the clinker chemical components are the weighted average of the coal ash and the chemical components of the burned raw materials; the same applies below.
Table 3-2 ingredient scheme 2 when limestone a accounts for 25% of the total limestone amount
Table 3-3 ingredient scheme 3 when limestone a accounts for 40% of the total limestone amount
Tables 3-4 ingredient mix scenario 4 where limestone a accounts for 40% of the total limestone amount
4 kinds of portland cement clinker with the kiln-out temperature of 60-100 ℃ are prepared, and the comparison condition of each index is shown in table 4:
table 44 ingredient scheme clinker index comparison
Description of the drawings: table 4 shows the alkali content R of the formulation 1 and the formulation 2 within the range of the compounding ratio2O is less than or equal to 0.60wt%, so that the target value of the clinker alkali content does not need to be set lower, and wet fly ash and siltstone are used for further replacing part of high alkali shale to adjust the batching scheme.
From the above table data, it can be seen that the limestone collocation limit isLimestone collocation is carried out in the range, and the blending scheme 1 and the blending scheme 2 can meet the requirement of the content R of clinker alkali2O is less than or equal to 0.60wt%, and the wet base mixing ratio of the siltstone with poor grindability and easy burning property in the raw material is less than or equal to 3.0wt%, the prepared low-alkali portland cement clinker has high strength and low consistency of below 24.0%, both the grindability and the burnability of the raw material reach better levels, the f-CaO content of the clinker is below 1.00%, and the yield of a raw material grinding platform can reach 240 t/h. The raw material grinding platform production, the clinker performance and the mine limestone resource comprehensive utilization are comprehensively considered, the batching scheme 2 is better, the utilization rate of the low-grade limestone A in the whole limestone can reach 25%, the wet base mixing ratio of the siltstone in the raw material is 2.13% and does not reach 3.00%, when the raw combustion material has certain fluctuation, the doping amount of the siltstone and the wet fly ash can be properly increased to replace part of high-alkali shale, and the alkali content of the raw clinker can be reduced and controlled within a certain space range.
Example 2
The low-alkali portland cement clinker is produced on a 4800t clinker/d novel dry production line by using a preparation method of the low-alkali portland cement clinker, wherein the control range of three rate values of the clinker is as follows: saturation ratio KH is 0.930 ± 0.020, silicic acid SM is 2.65 ± 0.10, and aluminum yield IM is 1.40 ± 0.10. The specific operation steps are as follows:
1) determining the limestone matching proportion range: according to the chemical components of limestone A and limestone B, iron ore, shale, wet fly ash and siltstone of different grades, the heat value, ash content and ash chemical component of coal powder and the heat consumption value 3136kJ/kg of clinker production unit on a kiln, when the proportion of low-grade limestone A in the total amount of limestone is not more than 29.88%, the alkali content R of clinker is obtained by solving and calculating through nonlinear programming2O is less than or equal to 0.60wt%, and the wet base mixing ratio of the siltstone with poor grindability and burnability in the raw meal is less than or equal to 3.0 wt%;
2) pretreatment of raw materials: the limestone, iron ore, shale, wet fly ash and powdered sandstone are crushed or screened, and different grades of limestone are matched and pre-homogenized within a matching limit range.
3) Raw material proportioning and grinding: according to the matching conditions of limestone with different grades, calculating a blending scheme of limestone, iron ore, shale, wet fly ash and siltstone by mass, uniformly mixing the limestone, iron ore, shale, wet fly ash and siltstone in proportion, feeding the mixture into a grinding system with a drying function for grinding and screening, controlling the water content of a ground finished product to be less than or equal to 1.0wt%, controlling the screen allowance of a 80-micrometer square-hole screen to be 20wt +/-2 wt%, and controlling the screen allowance of a 0.2-millimeter square-hole screen to be less than or equal to 2.0wt%, and obtaining dry powdery raw material;
4) preparing clinker: feeding the dry powdery raw materials mixed and homogenized in the step 3) into a suspension preheater and a decomposing furnace for preheating and decomposing, then feeding into a cement rotary kiln, carrying out high-temperature calcination at 1350-1450 ℃ to obtain a partially molten material with 24-27% of liquid phase amount, and controlling the pressure under a section of grate to be 5600-6200 Pa to fully cool the molten material on a grate cooler by a high-pressure blower so as to prepare the portland cement clinker with the kiln outlet temperature of 60-100 ℃;
5) determining the content of clinker alkali and adjusting the batching scheme: if the alkali content R is2And if the O is more than 0.60wt%, setting the target value of the clinker alkali content to be lower, further replacing part of high-alkali shale with wet fly ash and siltstone to adjust the batching scheme, and then producing the low-alkali portland cement clinker according to the steps 3) and 4).
In the clinker preparation process, the decomposition rate of raw materials entering a rotary kiln is 90-95%, the f-CaO content of clinker is 0.50-1.20%, and the vertical rise weight of clinker is 1270-1350 g/L by controlling the outlet temperature of a decomposing furnace at 865 +/-5 ℃ and the secondary air temperature at 1150 +/-50 ℃ at the kiln head.
The chemical composition of limestone, iron ore, shale, wet fly ash and siltstone and the characteristic results of the pulverized coal were the same as in example 1.
Similarly, in the step 2), the limestone A is still matched with the limestone B according to the proportion of 10%, 25% and 40% of the total amount of the limestone to produce the portland cement clinker, the limestone A accounts for 10% and 25% of the total amount of the limestone within the range of the matching proportion and is used for producing the low-alkali portland cement clinker, and the limestone A accounts for 40% of the total amount of the limestone not within the range of the matching proportion and is used for producing a portland cement clinker comparison sample.
In the step 3), the limestone A and the limestone respectively account for 10 percent, 25 percent and 40 percent of the total amount of the limestoneWhen B is matched, 5 raw material proportioning schemes are provided, as shown in tables 5-1 to 5-5, the chemical components of limestone in the tables are weight average values of limestone A and limestone B after being matched according to corresponding proportions, when the limestone A accounts for 25% of the total amount of the limestone, clinker production is carried out according to the proportioning scheme 6 in the table 5-2, the actually measured alkali content of the clinker is 0.61 wt% and is slightly more than 0.60wt%, therefore, under the limestone matching proportion, the target value of the alkali content of the clinker is set to be 0.58 wt%, the proportioning scheme 7 obtained by further replacing part of high alkali shale with wet fly ash and siltstone is shown in tables 5-3, and when the limestone A accounts for 40% of the total amount of the limestone, because the alkali content R of the clinker cannot be met at the same time2O is less than or equal to 0.60wt%, and the wet base mixing ratio of the siltstone with poor grindability and burnability in the raw material is less than or equal to 3.0wt%, two raw material proportioning schemes are correspondingly designed, and tables 5-4 are to meet the clinker alkali content R2Case 8 where O is 0.60wt% or less, and cases 9 where the wet base mixing ratio of the siltstone in the raw material is 3.0wt% or less, which is inferior in grindability and burnability, are satisfied, in tables 5 to 5.
TABLE 5-1 ingredient scheme 5 when limestone A accounts for 10% of the total limestone amount
TABLE 5-2 batching scheme 6 when limestone A accounts for 25% of limestone total
Tables 5-3 ingredient scheme 7 (Clinker R) where limestone A accounts for 25% of the total limestone2O is set to 0.58 wt%)
Tables 5-4 ingredient scheme 8 where limestone A accounts for 40% of the total limestone amount
Tables 5-5 ingredient protocol 9 when limestone A accounts for 40% of the total limestone amount
5 kinds of portland cement clinker with the kiln exit temperature of 60-100 ℃ are prepared, and the comparison conditions of various indexes are shown in table 6:
table 65 ingredient schemes for comparing various indexes of clinker produced
As can be seen from the data in the tables, the limestone collocation is carried out within the limit range of limestone collocation, and the blending scheme 5 and the blending scheme 7 can meet the clinker alkali content R2O is less than or equal to 0.60wt%, and the wet base mixing ratio of the siltstone with poor grindability and easy burning property in the raw material is less than or equal to 3.0wt%, the prepared low-alkali portland cement clinker has high strength and low consistency of below 24.0%, both the grindability and the burnability of the raw material reach better levels, the f-CaO content of the clinker is below 1.00%, and the yield of a raw material grinding table reaches above 480 t/per. The raw material grinding platform production, the clinker performance and the mine limestone resource are comprehensively considered, and the batching scheme 7 is better.
Table 7 shows the properties of low-alkali Portland cement grades 42.5 and 52.5 (low-alkali P.O 42.5 and low-alkali P.O 52.5) produced by using the low-alkali Portland cement clinker.
TABLE 7 Low base P.O 42.5 and Low base P.O 52.5 Performance
It can be seen from the table that the low alkali P.O 42.5 and the low alkali P.O 52.5 have low consistency, high strength and low alkali content R2O is less than 0.60 percent, and can completely meet the requirements of key projects on low-alkali grade cement.
The above description is provided for further details of the present invention with reference to specific examples, which should not be construed as limiting the scope of the present invention, but it should be understood that those skilled in the art can make several simple substitutions without departing from the spirit of the present invention.
Claims (4)
1. A low alkali portland cement clinker characterized by: the low-alkali silicate cement clinker is prepared by grinding, uniformly mixing, calcining at high temperature and cooling matched raw materials of limestone, iron ore, shale, wet fly ash and siltstone with different grades, wherein the alkali content R of the shale2O is more than or equal to 2.00 percent, the alkali content of the iron ore, the wet fly ash and the siltstone is less than 2.00 percent, and the wet base mixing ratio of the siltstone in the raw meal is less than or equal to 3.0 percent by weight; the limestone with different grades is high-alkali high-aluminum low-calcium limestone and low-alkali high-silicon high-calcium limestone, wherein the alkali content R of the high-alkali high-aluminum low-calcium limestone20.20 to 0.40 percent of O and Al content of aluminum oxide2O31.50 to 3.00 percent, the content of CaO is less than 48.00 percent, and the alkali content R of the low-alkali high-silicon high-calcium limestone2O is 0.05-0.20%, and the content of silicon dioxide SiO is2More than or equal to 7.00 percent, and the content of CaO in the calcium oxide is more than or equal to 48.00 percent; the low-alkali silicate cement clinker alkali content R2O is less than or equal to 0.60wt%, and the control range of the three-rate value is as follows: saturation ratio KH =0.930 ± 0.020, silicic acid SM =2.65 ± 0.10, aluminum yield IM =1.40 ± 0.10.
2. The method for producing a low alkali portland cement clinker according to claim 1, wherein: the method comprises the following steps:
1) determining the limestone matching proportion range: according to different limestone grades, determining a limestone matching proportion limit value to ensure the alkali content R of subsequently prepared clinker2O is less than or equal to 0.60wt%, and the wet base mixing ratio of the siltstone with poor grindability and burnability in the raw material is less than or equal to 3.0 wt%;
2) pretreatment of raw materials: crushing or screening limestone, iron ore, shale, wet fly ash and siltstone, and matching and pre-homogenizing limestone with different grades within a matching limit range;
3) raw material proportioning and grinding: according to the matching conditions of limestone with different grades, calculating a blending scheme of limestone, iron ore, shale, wet fly ash and siltstone by mass, uniformly mixing the limestone, iron ore, shale, wet fly ash and siltstone in proportion, feeding the mixture into a grinding system with a drying function for grinding and screening, controlling the water content of a ground finished product to be less than or equal to 1.0wt%, controlling the screen allowance of a 80-micrometer square-hole screen to be 20wt +/-2 wt%, and controlling the screen allowance of a 0.2-millimeter square-hole screen to be less than or equal to 2.0wt%, and obtaining dry powdery raw material;
4) preparing clinker: feeding the mixed and homogenized dry powdery raw materials into a suspension preheater and a decomposing furnace for preheating and decomposing, then feeding the raw materials into a cement rotary kiln, carrying out high-temperature calcination at 1350-1450 ℃ to obtain partially molten materials with 24-27% of liquid phase amount, and controlling the pressure under a section of grate to be 5600-6200 Pa to ensure that the molten materials are fully cooled by a high-pressure blower on the grate cooler to obtain portland cement clinker with the kiln discharge temperature of 60-100 ℃;
5) determining the content of clinker alkali and adjusting the batching scheme: if the alkali content R is2And if the O is more than 0.60wt%, setting the target value of the clinker alkali content to be lower, further replacing part of high-alkali shale with wet fly ash and siltstone to adjust the batching scheme, and then producing the low-alkali portland cement clinker according to the steps 3) and 4).
3. The method of claim 2, wherein: the limestone matching proportion range determined in the step 1) is determined according to chemical components of limestone, iron ore, shale, wet fly ash and siltstone of different grades, and heat value and ash of coal powderThe content, the chemical components of ash and the heat consumption value of the clinker per ton of the kiln are obtained by solving and calculating through nonlinear programming, thereby achieving the clinker alkali content R in the raw material proportioning scheme2O is less than or equal to 0.60wt percent, and the wet base mixing ratio of the siltstone with poor grindability and easy burning property in the raw meal is less than or equal to 3.0wt percent.
4. The method of claim 2, wherein: the two materials of the wet fly ash and the siltstone in the step 3) can be only mixed into one material.
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| CN113264698B (en) * | 2021-07-05 | 2022-07-26 | 中材萍乡水泥有限公司 | Portland cement clinker comprehensively utilizing low-grade limestone and production process thereof |
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