CN111517679A

CN111517679A - Multi-solid waste early strength cement and preparation method thereof

Info

Publication number: CN111517679A
Application number: CN202010381223.2A
Authority: CN
Inventors: 张延年; 于洋; 顾晓薇; 李志军; 陈志燕; 杜松岩; 董宁; 李琦琦; 陈昊; 刘柏男; 张文洁; 崔长青; 王亭; 张于于; 康楠; 王铁源; 闫明程
Original assignee: Individual
Current assignee: Individual
Priority date: 2020-05-08
Filing date: 2020-05-08
Publication date: 2020-08-11

Abstract

The invention discloses multi-solid waste early strength cement and a preparation method thereof, wherein the multi-solid waste early strength cement is prepared from the following raw materials in parts by weight: 50-60 parts of cement clinker, 15-20 parts of graphite tailings, 5-7 parts of aluminum sulfate slag, 10-15 parts of slag, 5-6 parts of desulfurized gypsum, 0.5-0.9 part of additive and 0.05-0.1 part of grinding aid; the cement raw meal is prepared from the following raw materials in parts by weight: 81-88 parts of limestone, 7-8 parts of sandstone, 3-4 parts of iron ore powder and 8-9 parts of fly ash. According to the invention, the early strength agent and the grinding aid are added, so that the early stage of solid waste can better participate in cement hydration reaction to generate more tricalcium silicate, the early strength performance of the prepared concrete is better, the initial setting time and the final setting time of the cement are shortened, the effect of fully utilizing the solid waste is achieved, the cost is saved, and the solid waste is utilized.

Description

Multi-solid waste early strength cement and preparation method thereof

Technical Field

The invention relates to cement, in particular to multi-solid waste early strength cement and a preparation method thereof.

Background

With the continuous development of industrial technology, various industrial solid wastes or waste residues are increased day by day, aiming at the problems of huge storage amount, serious environmental pollution and difficult safe disposal of various industrial solid wastes, the utilization of low-cost, large-scale and high-valued resources is taken as a target, and how to utilize the industrial solid wastes and the waste residues becomes a problem to be solved. Meanwhile, the utilization rate of the tailings in China is low and is only 8.2%, and how to effectively utilize the tailings also becomes a problem to be solved.

C in conventional portland cement clinker₃The content of S is generally only 40-55%, and C in the early-strength portland cement clinker₃The content of S is more than 65 percent, and because the early strength is low and the initial setting and final setting time are long when the solid waste is utilized to produce cement, the influence on the bearing of structures and members is difficult to estimate, and the problem to be solved is how to stimulate the early activity of industrial solid waste and waste residue to produce cement with high early strength and short initial setting and final setting time.

Disclosure of Invention

The invention aims to provide multi-solid waste early strength cement and a preparation method thereof.

In order to solve the technical problems, the technical scheme adopted by the invention is as follows:

the multi-solid waste early strength cement is prepared from the following raw materials in parts by weight: 50-60 parts of cement clinker, 15-20 parts of graphite tailings, 5-7 parts of aluminum sulfate slag, 10-15 parts of slag, 5-6 parts of desulfurized gypsum, 0.5-0.9 part of additive and 0.05-0.1 part of grinding aid;

the cement clinker is prepared from the following raw materials in parts by weight: 95.17-95.45 parts of burned cement raw material and 4.55-4.83 parts of coal ash;

the cement raw material is prepared from the following raw materials in parts by weight:

81-88 parts of limestone, 7-8 parts of sandstone, 3-4 parts of iron ore powder and 8-9 parts of fly ash.

Further, the multi-solid waste early strength cement is prepared from the following raw materials in parts by weight:

55 parts of cement clinker, 20 parts of graphite tailings, 5 parts of aluminum sulfate slag, 15 parts of slag, 5 parts of desulfurized gypsum, 0.5 part of additive and 0.05 part of grinding aid;

the cement clinker is prepared from the following raw materials in parts by weight: 95.44 parts of burned cement raw material and 4.56 parts of coal ash;

81 parts of limestone, 7 parts of sandstone, 4 parts of iron ore powder and 8 parts of fly ash.

Further, the additive is aluminum sulfate.

Further, the grinding aid is triethanolamine.

The preparation method of the multi-solid waste early strength cement comprises the following steps:

preparing cement raw materials: grinding by adopting a wet grinding process: feeding the raw materials into a raw material ball mill according to respective weight parts, simultaneously adding water for wet milling, pumping slurry into a slurry reservoir for later use after grinding, then placing the slurry into a slurry reservoir for stirring, pumping into a filter press for dehydration after uniform stirring, controlling the water content of a filter cake after filter pressing to be 20-30%, then feeding the filter cake into a drying crusher for drying the filter cake into fine powder of cement raw materials with the water content of 1-3% and the screen residue of a 0.08mm square-hole screen of less than 10%, and then carrying out homogenization treatment on the cement raw materials by a homogenization reservoir and then starting calcining;

preparing cement clinker: in the calcination stage, the cement raw materials in parts by weight sequentially pass through a preheater, a decomposing furnace and a rotary kiln, and gradually move to the kiln head by means of the inclination of the rotary kiln and the rotation of 3.97r/min, then are sintered into cement clinker at the kiln head, then are sent into a grate cooler for cooling, are crushed by a hammer crusher at the tail part of the grate cooler, are discharged onto a conveyor, and are conveyed to a clinker warehouse; the specific process is as follows: the preheater heats cement raw materials by using waste heat discharged by a decomposing furnace and a rotary kiln, the decomposing furnace moves the original decomposing task in the rotary kiln to the inside of the decomposing furnace to continuously heat the cement raw materials, the outlet temperature of the decomposing furnace is controlled to be about 870 ℃, the outlet negative pressure is about-800 Pa, then the cement raw materials are sent into the rotary kiln to be continuously calcined, the kiln temperature is 1000-1450 ℃, the negative pressure at the tail of the rotary kiln is controlled to be about-100 Pa, the tertiary air temperature entering the decomposing furnace from a grate cooler through a tertiary air pipe is controlled to be about 830 ℃, the grate cooler directly enters the rotary kiln, the secondary air temperature from the kiln head to the kiln tail is controlled to be about 1050 ℃, a blower directly enters a kiln system from the air, the primary air brings the coal ash with the weight part into the kiln to assist combustion, and finally the cement clinker is prepared after being cooled by the grate cooler and is placed in a clinker warehouse;

uniformly mixing the cement clinker with the graphite tailings, the aluminum sulfate slag, the desulfurized gypsum, the additive and the grinding aid in parts by weight, and then grinding for 40 min.

The invention has the advantages and beneficial effects that:

1) the multi-solid waste early strength cement provided by the invention takes various solid wastes as production raw materials, and the early strength agent aluminum sulfate and the grinding aid are added, so that the solid wastes better participate in a cement hydration reaction in the early stage to generate more tricalcium silicate, the prepared concrete has better early strength and high early strength, the initial setting and final setting time of the cement is shortened, the effect of fully utilizing the solid wastes is achieved, the cost is saved, the solid wastes are utilized, and the strength grade of the cement reaches the national standard.

2) The aluminum sulfate and the aluminum sulfate slag adopted by the invention are both taken from the same manufacturer, and the common utilization of industrial products and corresponding industrial solid wastes is realized.

3) In the preparation process, the grinding aid triethanolamine is added, so that the hydration activity of the solid waste can be improved in the grinding time, and the specific surface area of the ground solid waste is increased, so that the corresponding activity index is also increased, the grinding degree of the solid waste can be improved, and the cement performance can be improved.

4) The cement clinker replacement rate of the invention reaches more than 40 percent, and simultaneously, the invention can ensure the strength of the produced cement and bring good enterprise benefit.

Detailed Description

The present invention is described in detail below with reference to examples:

example 1:

the embodiment of the invention relates to multi-solid waste early strength cement which is prepared from the following raw materials in parts by weight:

The additive is aluminum sulfate, and the grinding aid is triethanolamine.

preparing cement clinker: and in the calcination stage, the cement raw materials in parts by weight sequentially pass through a preheater, a decomposing furnace and a rotary kiln, gradually move to the kiln head by virtue of the inclination of the rotary kiln and the rotation of 3.97r/min, then are sintered into cement clinker at the kiln head, are sent into a grate cooler for cooling, are crushed by a hammer crusher at the tail part of the grate cooler, are discharged onto a conveyor, and are conveyed to a clinker warehouse.

The specific process is as follows: the preheater heats cement raw materials by using waste heat discharged by a decomposing furnace and a rotary kiln, the decomposing furnace moves the original decomposing task in the rotary kiln to the inside of the decomposing furnace to continuously heat the cement raw materials, the outlet temperature of the decomposing furnace is controlled at 870 ℃, the negative pressure of the outlet is controlled at-800 Pa, then the cement raw materials are sent into the rotary kiln to be continuously calcined, the kiln temperature is 1200 ℃, the negative pressure of the tail of the rotary kiln is controlled at-100 Pa, the tertiary air temperature entering the decomposing furnace from a grate cooler through a tertiary air pipe is controlled at 830 ℃, the tertiary air directly enters the rotary kiln from the grate cooler, the secondary air temperature from the kiln head to the kiln tail is controlled at 1050 ℃, the air directly enters a kiln system from the air by a blower, the coal ash with the weight part is taken into the kiln by primary air to support combustion, and finally, cement clinker is prepared after being cooled by the grate.

Uniformly mixing the cement clinker with the graphite tailings, the aluminum sulfate slag, the desulfurized gypsum, the additive and the grinding aid in parts by weight, grinding for 40min, and preparing the cement with the standard of more than 32.5R through mechanical activation and chemical excitation. The chemical excitation means that when the cement is applied to actual engineering, the hydration of the cement can be promoted due to the addition of the aluminum sulfate early strength agent, and the aim of increasing the strength is further fulfilled.

When the cement clinker is calcined in the rotary kiln, the ratio of kiln head coal to kiln tail coal is 1 (1 +/-0.1).

The chemical composition of the cement raw meal in this example is shown in table 1 (%):

table 1:

name (R)	Parts by weight	Burning vector	CaO	Al₂O₃	Fe₂O₃	SiO₂
							Limestone	81	43.33	51.4	0.16	0.1	0.17
Iron ore powder	4	3.22	5.5	3.99	57.23	21.44
							Sandstone	7	0.78	-	4.92	0.72	92
Fly ash	8	4.21	0.85	26.5	4.31	57.11

The chemical composition of the dry cement raw material is shown in table 2 (%):

table 2:

name (R)	Parts by weight	Burning vector	CaO	Al2O3	Fe2O3	SiO2
							Limestone	81	35.07	41.6	0.12	0.08	0.14
Iron ore powder	4	0.13	0.22	0.17	2.28	0.86
							Sandstone	7	0.05	-	0.35	0.05	6.44
Fly ash	8	0.34	0.07	2.12	0.34	4.57
							Dry raw meal	100	35.6	42.1	2.76	2.75	12.01

The cement clinker chemical composition is shown in table 3 after calculation (%):

table 3:

name (R)	Mixing ratio	CaO	Al2O3	Fe2O3	SiO2
						Burning the raw material	95.44	62.4	4.28	4.26	18.65
Coal ash	4.56	0.22	1.62	0.18	2.45
						Cement clinker	100.00	62.62	5.9	4.44	21.1

Calculating the clinker composition:

KH=0.87

SM=2.04

IM=1.32

wherein, the three required values are: KH =0.88 ± 0.01, SM =2.1 ± 0.1, 1.3 ± 0.1.

Wherein, when the lime saturation coefficient is more than 1, free calcium oxide is generated in the clinker, so KH is required to be controlled to be not more than 1.

Wherein, the clinker minerals comprise:

C₃S=3.80（3KH-2）SiO₂=3.8×（3×0.87-2）×21.1=48.91%

C₂S=8.60（1-KH）SiO₂=8.60×（1-0.87）×21.1=23.58%

C₃A=2.65(AL₂O₃-0.64Fe₂O₃) =2.65×（5.9-0.64×4.44）=7.98%

C₄AF=3.04Fe₂O₃=3.04×4.44=13.49%。

example 2:

the multi-solid waste early strength cement is prepared from the following raw materials in parts by weight: 50 parts of cement clinker, 17 parts of graphite tailings, 6 parts of aluminum sulfate slag, 12 parts of slag, 6 parts of desulfurized gypsum, 0.7 part of additive and 0.07 part of grinding aid;

the cement clinker is prepared from the following raw materials in parts by weight: 95.45 parts of burned cement raw material and 4.55 parts of coal ash;

88 parts of limestone, 8 parts of sandstone, 4 parts of iron ore powder and 9 parts of fly ash.

The rest is the same as example 1.

The preparation method of the multi-solid waste early strength cement of the embodiment is different from the preparation method of the embodiment 1 only in the step two, and in the embodiment: in the calcination stage, the cement raw materials in parts by weight sequentially pass through a preheater, a decomposing furnace and a rotary kiln, and gradually move to the kiln head by means of the inclination of the rotary kiln and the rotation of 3.97r/min, then are sintered into cement clinker at the kiln head, then are sent into a grate cooler for cooling, are crushed by a hammer crusher at the tail part of the grate cooler, are discharged onto a conveyor, and are conveyed to a clinker warehouse; the specific process is as follows: the preheater heats cement raw materials by using waste heat discharged by a decomposing furnace and a rotary kiln, the decomposing furnace moves the original decomposing task in the rotary kiln to the inside of the decomposing furnace to continuously heat the cement raw materials, the outlet temperature of the decomposing furnace is controlled at 860 ℃, the negative pressure of the outlet is controlled at-790 Pa, then the cement raw materials are sent into the rotary kiln to be continuously calcined, the kiln temperature is 1000 ℃, the negative pressure of the tail of the rotary kiln is controlled at-90 Pa, the tertiary air temperature entering the decomposing furnace from a grate cooler through a tertiary air pipe is controlled at 830 ℃, the tertiary air directly enters the rotary kiln from the grate cooler, the secondary air temperature from the kiln head to the kiln tail is controlled at 1040 ℃, an air blower directly enters a kiln system from the air, the coal ash with the weight part is taken into the kiln to support combustion, and finally the cement clinker is prepared after being cooled by the grate cooler and is placed in; the rest is the same as example 1.

The chemical composition of the cement raw meal in this example is shown in table 4 (%):

table 4:

name (R)	Parts by weight	Burning vector	CaO	Al₂O₃	Fe₂O₃	SiO₂
							Limestone	88	43.33	51.4	0.16	0.1	0.17
Iron ore powder	4	3.22	5.5	3.99	57.23	21.44
							Sandstone	8	0.78	-	4.92	0.72	92
Fly ash	9	4.21	0.85	26.5	4.31	57.11

The chemical composition of the dry cement raw material is shown in table 5 (%):

table 5:

name (R)	Parts by weight	Burning vector	CaO	Al2O3	Fe2O3	SiO2
							Limestone	88	34.95	42.5	0.13	0.08	0.1
Iron ore powder	4	0.15	0.22	0.15	2.20	0.8
							Sandstone	8	0.1	-	0.37	0.07	7.0
Fly ash	9	0.41	0.1	2.54	0.42	4.68
							Dry raw meal	109	35.61	42.82	3.19	2.77	12.58

The cement clinker chemical composition is shown in table 6 after calculation (%):

table 6:

name (R)	Mixing ratio	CaO	Al2O3	Fe2O3	SiO2
						Burning the raw material	95.45	63.57	4.69	4.07	18.97
Coal ash	4.55	0.25	1.22	0.18	2.25
						Clinker	100	63.82	5.91	4.25	21.22

Calculating the clinker composition:

KH=0.8836

SM=2.0885

IM=1.3905

wherein, the three required values are: KH =0.89 ± 0.01, SM =2.1 ± 0.1, 1.3 ± 0.1.

Wherein, the clinker minerals comprise:

C3S=3.80（3KH-2）SiO2=3.8×（3×0.8836-2）×21.22=52.48%

C2S=8.60（1-KH）SiO2=8.60×（1-0.8836）×21.22=21.24%

C3A=2.65(AL2O3-0.64Fe2O3) =2.65×（5.91-0.64×4.25）=8.45%

C4AF=3.04Fe2O3 =3.04×4.25=12.25%。

example 3:

the multi-solid waste early strength cement is prepared from the following raw materials in parts by weight: 60 parts of cement clinker, 15 parts of graphite tailings, 7 parts of aluminum sulfate slag, 10 parts of slag, 5 parts of desulfurized gypsum, 0.9 part of additive and 0.1 part of grinding aid;

the cement clinker is prepared from the following raw materials in parts by weight: 95.17 parts of burned cement raw material and 4.83 parts of coal ash;

85 parts of limestone, 7 parts of sandstone, 3 parts of iron ore powder and 8 parts of fly ash. The rest is the same as example 1.

The preparation method of the multi-solid waste early strength cement of the embodiment is different from the preparation method of the embodiment 1 only in the step two, and in the embodiment: in the calcination stage, the cement raw materials in parts by weight sequentially pass through a preheater, a decomposing furnace and a rotary kiln, and gradually move to the kiln head by means of the inclination of the rotary kiln and the rotation of 3.97r/min, then are sintered into cement clinker at the kiln head, then are sent into a grate cooler for cooling, are crushed by a hammer crusher at the tail part of the grate cooler, are discharged onto a conveyor, and are conveyed to a clinker warehouse; the specific process is as follows: the preheater heats cement raw materials by using waste heat discharged by a decomposing furnace and a rotary kiln, the decomposing furnace moves the original decomposing task in the rotary kiln to the inside of the decomposing furnace to continuously heat the cement raw materials, the outlet temperature of the decomposing furnace is controlled at 880 ℃, the negative pressure of the outlet is controlled at-810 Pa, then the cement raw materials are sent into the rotary kiln to be continuously calcined, the kiln temperature is 1450 ℃, the negative pressure of the tail of the rotary kiln is controlled at-110 Pa, the temperature of tertiary air entering the decomposing furnace from a grate cooler through a tertiary air pipe is controlled at 840 ℃, the tertiary air directly enters the rotary kiln from the grate cooler, the temperature of secondary air from the kiln head to the kiln tail is controlled at 1060 ℃, a blower directly enters a kiln system from the air, the coal ash with the weight part is taken into the kiln by primary air to support combustion, and finally cement clinker is prepared after being cooled by the grate cooler and; the rest is the same as example 1.

The chemical composition of the cement raw meal in this example is shown in table 7 (%):

table 7:

name (R)	Parts by weight	Burning vector	CaO	Al₂O₃	Fe₂O₃	SiO₂
							Limestone	85	43.33	51.4	0.16	0.1	0.17
Iron ore powder	3	3.22	5.5	3.99	57.23	21.44
							Sandstone	7	0.78	-	4.92	0.72	92
Fly ash	8	4.21	0.85	26.5	4.31	57.11

The chemical composition of the dry cement raw material is shown in table 8 (%):

table 8:

name (R)	Parts by weight	Burning vector	CaO	Al2O3	Fe2O3	SiO2
							Limestone	85	35.76	42.41	0.15	0.11	0.14
Iron ore powder	3	0.1	0.17	0.12	1.82	0.62
							Sandstone	7	0.06	-	0.31	0.1	6.25
Fly ash	8	0.36	0.07	2.01	0.38	4.44
							Dry raw meal	103	36.28	42.65	2.59	2.41	11.45

The cement clinker chemical composition is shown in table 9 after calculation (%):

table 9:

name (R)	Mixing ratio	CaO	Al2O3	Fe2O3	SiO2
						Burning the raw material	95.17	63.70	3.87	3.59	19.27
Coal ash	4.83	0.22	1.22	0.18	2.55
						Clinker	100	63.92	5.19	3.77	21.82

Calculating the clinker composition:

KH=0.884

SM=2.435

IM=1.376

wherein, the three required values are: KH =0.89 ± 0.01, SM =2.4 ± 0.1, 1.4 ± 0.1.

Wherein, the clinker minerals comprise:

C3S=3.80（3KH-2）SiO2=3.8×（3×0.884-2）×21.82=54.06%

C2S=8.60（1-KH）SiO2=8.60×（1-0.884）×21.82=21.77%

C3A=2.65(AL2O3-0.64Fe2O3) =2.65×（5.19-0.64×3.77）=7.36%

C4AF=3.04Fe2O3 =3.04×3.77=11.46%。

Claims

1. the multi-solid waste early strength cement is characterized by being prepared from the following raw materials in parts by weight: 50-60 parts of cement clinker, 15-20 parts of graphite tailings, 5-7 parts of aluminum sulfate slag, 10-15 parts of slag, 5-6 parts of desulfurized gypsum, 0.5-0.9 part of additive and 0.05-0.1 part of grinding aid;

2. The multi-solid waste early strength cement as claimed in claim 1, which is prepared from the following raw materials in parts by weight:

3. The multi-solid waste early strength cement as claimed in claim 1 or 2, wherein said admixture is aluminum sulfate.

4. The multi-solid waste early strength cement of claim 1 or 2, characterized in that the grinding aid is triethanolamine.

5. The method for preparing multi-solid waste early strength cement according to claim 1 or 2, characterized by comprising the steps of: