CN108794052B

CN108794052B - Sludge shale heat-preservation microporous brick and preparation method thereof

Info

Publication number: CN108794052B
Application number: CN201810582153.XA
Authority: CN
Inventors: 吴凯; 张林涛; 苏宇峰; 宋锡铭; 李响
Original assignee: Tongji University
Current assignee: Tongji University
Priority date: 2018-06-07
Filing date: 2018-06-07
Publication date: 2021-06-04
Anticipated expiration: 2038-06-07
Also published as: CN108794052A

Abstract

The invention relates to a sludge shale heat-insulating microporous brick and a preparation method thereof, wherein the sludge shale heat-insulating microporous brick is prepared from the following raw materials in percentage by mass: 70-75% of shale, 15-20% of sludge and 5-15% of coal gangue, and sodium carboxymethylcellulose accounting for 0.5% of the total mass of the mixture is added, and the preparation method comprises the steps of crushing raw materials, proportioning and mixing, grinding the raw materials, secondary screening, mixing based on the granularity proportioning, testing and forming the water content, adding water and stirring, aging and curing, multi-stage drying, testing the thermal property of the raw materials, setting the baking stage and baking the blank. The shale, the sludge, the coal gangue and the additive are utilized, so that the sludge and the coal gangue are recycled in the baked brick, the sludge and the coal gangue are consumed and treated, the environmental load is reduced, and the sludge and the coal gangue are used as pore-forming agents of the baked brick, so that the baked brick has the characteristics of light weight, heat preservation, heat insulation, sound absorption, noise reduction and the like.

Description

Sludge shale heat-preservation microporous brick and preparation method thereof

Technical Field

The invention relates to the field of building materials, in particular to a sludge shale heat-insulating microporous brick and a preparation method thereof.

Background

Along with the acceleration of the urbanization process of China, the urban scale is continuously enlarged and the urban population is increased rapidly, the discharge amount of sludge generated by industry and daily life is increased rapidly, and the treatment pressure of sludge is increased more and more. Environmental protection treatment and resource utilization of sludge have become a focus of attention. The loss on ignition of the sludge can reach 50 percent, and the method has application potential as a pore-forming agent of the sintered brick. Organic matters in the sludge volatilize at high temperature, pores are left in situ to form a porous structure, and the heat preservation and heat insulation performance of the baked bricks is favorably improved. In addition, one of the main raw materials of the baked brick is clay, and the main chemical components are silicon dioxide, aluminum oxide, calcium oxide, iron oxide and the like, which are similar to the components of the sludge. It is therefore contemplated that the sludge may be incorporated into the raw material of the clinker brick to replace a portion of the clay within the allowable range of chemical composition. In addition, the domestic sludge has a large proportion of organic matters and a certain combustion heat value, so that the energy consumption can be reduced when the domestic sludge is used for making bricks. Therefore, the sludge is properly used as the raw material of the sintered wall material to replace partial clay, so that solid waste can be recycled, the requirements of the sintered brick on light weight and improvement of heat insulation performance can be met, and the concepts of energy conservation, waste utilization and environmental protection are met.

Clay is the main raw material of the baked brick. The conventional sintering method consumes a large amount of clay, resulting in destruction of cultivated land. Taking the distribution and the yield of the sintered brick factories in China as an example, the current annual yield is about 1 trillion blocks, so that the clay-sticking resources are greatly consumed, and the quantity and the quality of the existing farmlands in China are irreversibly influenced. To change this trend, a suitable substitute for clay must be found. Shale is a argillaceous rock, contains more clay minerals, has the main chemical composition basically the same as that of clay, and can meet the requirements of raw materials of baked bricks. The reserve occupation amount of shale rock in China can reach about 77% of the total territorial area, and the shale rock is a sedimentary rock mineral resource with obvious application advantages and gradually becomes one of the most abundant resource reserve objects in the actual content of China. Therefore, the shale is used as the raw material of the baked brick, which not only can meet the requirements of the baked brick on the raw material, but also can avoid the damage to the cultivated land. In some hilly areas, the exploitation of shale may even be done to create fields.

The coal gangue is associated black rock with carbon content generated in the coal forming process, is discharged as solid waste in the coal mining and coal washing processes, and the yield of the coal gangue accounts for about 5% -25% of the coal mining amount. Coal gangue, which has accumulated in china, has reached 10 million tons and is increasing at a rate of 1 million tons per year. If the coal gangue is discarded and stacked, a large amount of land is occupied. The coal gangue contains a large amount of sulfide, and the escape or leaching of the sulfide can cause air and water pollution and has serious threat to the environment and human health. Meanwhile, the coal gangue has spontaneous combustion risk and great potential safety hazard. The main components of coal gangue, such as silicon oxide, aluminum oxide, calcium oxide, iron oxide, etc., can also be used as raw materials of sintered wall materials. Meanwhile, a certain amount of carbon exists in the coal gangue, and in the roasting process, not only is the heat released and the roasting energy consumption is saved, but also pores are left in situ after the carbon is combusted, and a certain pore-forming effect is achieved.

Disclosure of Invention

Based on the background technology, the invention provides the heat-preservation microporous brick prepared by utilizing the sludge, the coal gangue, the shale and a proper additive under certain process conditions, scientifically and efficiently utilizes bulk wastes such as the sludge, the coal gangue and the like, reduces the environmental load, improves the resource utilization level and the commercial added value of the sludge and the coal gangue, and develops the high-performance green building material.

The invention is realized by the following technical scheme:

the sludge shale heat-insulating microporous brick is prepared from the following raw materials in percentage by mass: according to absolute dry mass conversion, 70-75% of shale, 15-20% of sludge and 5-15% of coal gangue are added, and sodium carboxymethylcellulose accounting for 0.5% of the total mass of the mixture is added.

Further, shale, mud and gangue adopt powder particulate matter, sieve once and sieve twice through 2mm sieve and 0.2mm sieve respectively, and the mass ratio of once sieving and the powder after sieving twice is 4: 6, the mixture has enough plasticity by controlling the particle size distribution of the mixture and the particle grading, so that the forming is facilitated, and the difficulty brought to the drying of the green body due to the over-small particle size can be avoided; secondly, it is comparatively reasonable to guarantee the grain composition, and the mixture is evenly mixed, and the tiny particle is filled between the large granule, is favorable to baked brick mechanical properties.

A preparation method of a sludge shale heat-insulating microporous brick specifically comprises the following steps:

(1) respectively crushing the dried sludge, shale and coal gangue in a crushing device to obtain granules, mixing the granules according to a ratio, and then grinding and sieving to obtain mixture powder;

(2) adding sodium carboxymethylcellulose (CMC) into the mixture powder as a flocculating agent, adding water, stirring to prepare a pug, and placing the pug into a curing chamber for aging;

(3) placing the aged pug into a mold to be molded into a blank body, and drying the molded blank body to ensure that the moisture content of the dried blank body is lower than 5%;

(4) and (4) placing the dried blank into a sintering furnace for roasting to obtain the product.

Further, the crushing device in the step (1) is a jaw crusher, a hammer crusher or a fine crusher, and the particle size of the crushed particles is below 5 mm.

Further, the plasticity index of the pug is controlled to be 10-17 in the step (2).

Further, the water addition amount is specifically determined by the following method: adding water and stirring the mixture powder until the mixture powder shows plasticity from the powder, then filling the soil sample cup with the pug, leveling the cup mouth, measuring the plastic deformation capability of the pug by the depth of the cone of the soil liquid plastic limit tester dropping into the soil sample cup, and when the depth is less than 6mm, continuously adding water and stirring until the depth is 6 mm. Then taking out part of the pug, putting the pug into an oven and drying to obtain the molding moisture content of the pug, wherein the molding moisture content of the obtained blank is 20-25%;

further, the step (2) is to put the pug into a curing chamber with the relative humidity of more than 85 percent for aging for 22 to 26 hours.

Further, drying the formed blank in the step (3) at 35-45 ℃ for 1.5-2.5h, raising the drying temperature to 100-110 ℃, and drying for 3.5-4.5 h.

Further, the temperature in the step (4) is increased to the preheating temperature at the temperature increasing rate of 5 ℃/min, the temperature is maintained for 30min, then the temperature is increased to 950 ℃ at the temperature of 900 ℃ at the speed of 5 ℃/min, the temperature is maintained for 1h at the highest temperature, and then the furnace is cooled to the room temperature.

Furthermore, the preheating temperature is 400-500 ℃, is determined by the temperature range of the thermogravimetric curve weight loss peak value of the sludge and the coal gangue, is generally 400-500 ℃, is set as the preheating stage, is beneficial to the complete pyrolysis or combustion of organic matters in the green body, and leaves pores at the original position, so that the pore structure of the green body is adjusted, the heat insulation performance of the brick is improved, and the condition of 'black core' in the green body due to the fact that the organic matters and carbon are sealed in the green body and are not completely combusted is avoided.

The invention comprehensively considers the urgency of recycling sewage sludge and coal gangue and the structural characteristics of porosity, light weight and the like required by the heat-preservation microporous baked brick, finds out a proper raw material proportion and a preparation flow, prepares the heat-preservation microporous brick by using the coal gangue, the sewage sludge, the shale and the admixture as raw materials and combining a proper firing system and a proper process method, thereby not only reducing the serious burden of the sludge and the coal gangue on the environment, but also reducing the additional disposal cost; and the sewage sludge and the coal gangue are utilized to improve the pore structure of the baked brick, so that the heat-insulating microporous baked brick with low volume density, excellent heat-insulating property and excellent mechanical property is obtained.

Compared with the prior art, the invention has the following beneficial effects:

1. the raw materials adopted by the invention are shale, sludge, coal gangue and an additive, so that the sludge and the coal gangue are recycled in the baked brick, the sludge and the coal gangue are not only consumed and treated, and the environmental load is reduced, but also the sludge and the coal gangue are commonly used as pore-forming agents of the baked brick, so that the baked brick has the characteristics of light weight, heat preservation, heat insulation, sound absorption, noise reduction and the like;

2. the invention adopts a secondary sieving method to control the gradation distribution of mixed raw materials, determines the optimal forming water content by measuring the deformation capability of the mud through the cone of a soil liquid plastic limit tester at the falling depth of the mud, is assisted by a CMC flocculating agent to ensure that the mud has good plasticity and is easy to form, solves the problem of difficult mixed forming caused by mixing sludge and coal gangue, and obtains a green blank with higher strength and low drying shrinkage rate;

3. the preheating temperature is set through a thermogravimetric curve of the raw material, so that not only is the sludge and the coal gangue completely combusted or pyrolyzed, but also the effect of the sludge and the coal gangue as pore-forming agents is fully exerted, the pore structure of the blank body is improved, and the problem of 'black core' caused by the fact that organic matters in the sludge or carbon in the coal gangue are sealed in the blank body and are not completely combusted, and a reducing environment is formed in the blank body is avoided;

4. the heat-insulating microporous brick obtained by the invention has good appearance quality, no crack, no corner defect, no 'black core' in the interior, good mechanical property and heat-insulating property, and the volume density of 1300-³The compressive strength is 17MPa to 25MPa, the thermal conductivity coefficient is 0.35 to 0.45W/(m.K), and the water absorption rate after 24 hours of soaking at normal temperature is 18 percent to 24 percent.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail below with reference to specific examples. The specific embodiments described herein are merely illustrative of the invention and are not intended to be limiting.

Example 1

A preparation method of a sludge shale heat-insulating microporous brick comprises the following steps:

s1: placing sludge with the water content of more than 90% from a sewage treatment plant into a solarization plant, tedding for 3 days, and then drying the sludge to ensure that the water content is lower than 10% to obtain a sludge block;

s2: respectively putting shale, sludge and coal gangue in a jaw crusher, a hammer crusher and a fine crusher to obtain shale particles, sludge particles and coal gangue particles, wherein the particle size of the shale particles, the sludge particles and the coal gangue particles is less than 5 mm;

s3: mixing 75%, 15% and 10% of shale particles, sludge particles and coal gangue particles in mass ratio after absolute dry mass conversion, grinding for 15-20min by a planetary ball mill, and sieving to obtain mixture powder; and after grinding, performing primary screening and secondary screening on the powder respectively in a 2mm sieve and a 0.2mm sieve, and weighing 4: placing the primary sieved powder and the secondary sieved powder in a stirrer according to the mass ratio of 6;

s4: weighing 0.5% of CMC powder based on the mass of the mixture, putting the CMC powder into a stirrer as a flocculating agent, stirring for 3min, taking out part of dry mixture powder, filling the mixture into a soil sample cup, leveling the cup mouth, weighing the plastic deformation capacity of the pug by the depth of a cone of a soil liquid plastic limit tester falling into the soil sample cup, when the depth is less than 6mm, continuously adding water until the depth is 6mm, and then taking out part of the pug, putting the pug into an oven, and drying to obtain the mixture with the molding water content of 24%. Weighing 24% of water by mass of the mixture at the moment according to the obtained water content, adding the water into a stirrer, stirring and mixing for 5min to obtain pug, then conveying the pug to a curing chamber with the relative humidity of more than 85%, and aging for 24h to increase the forming performance of the pug to obtain a mixture with the plasticity index of 13;

s5: placing the aged mud material in a mould to form a blank body, and pressing the blank body;

s6: drying the molded blank at 40 ℃ for 2h, raising the drying temperature to 105 ℃, and drying for 4h, wherein the moisture content of the dried blank is lower than 5%;

s7: and setting the preheating temperature to 400 ℃ according to the thermogravimetric curves of the sludge and the coal gangue. And (3) placing the dried blank into a sintering furnace, heating to the preheating temperature of 400 ℃ at the heating rate of 5 ℃/min, preserving the temperature for 30min, heating to 900 ℃ at the temperature of 5 ℃/min, preserving the temperature for 1h at the highest temperature, and cooling along with the furnace.

The performance parameters of the obtained heat-insulating microporous brick are shown in the table 1.

Table 1 example 1 insulating microporous brick performance parameters

Example 2

s3: mixing 70%, 15% and 15% of shale particles, sludge particles and coal gangue particles in mass ratio after absolute dry mass conversion, grinding for 15-20min by a planetary ball mill, and sieving to obtain mixture powder; and after grinding, performing primary screening and secondary screening on the powder respectively in a 2mm sieve and a 0.2mm sieve, and weighing 4: placing the primary sieved powder and the secondary sieved powder in a stirrer according to the mass ratio of 6;

s4: weighing 0.5% of CMC powder of the mass of the mixture as a flocculating agent, putting the CMC powder into a stirrer, stirring for 3min, taking out part of dry mixture powder, filling the mixture into a soil sample cup, leveling the cup mouth, weighing the plastic deformation capacity of the pug by the depth of a cone of a soil liquid plastic limit tester falling into the soil sample cup, when the depth is less than 6mm, continuously adding water until the depth is 6mm, and then taking out part of the pug at the moment, putting the pug into an oven, and drying to obtain the forming water content of the pug. Weighing water accounting for 22% of the mass of the mixture at the moment according to the obtained water content of 22%, adding the water into a stirrer, stirring and mixing for 5min to obtain pug, then conveying the pug to a curing chamber with the relative humidity of more than 85%, and aging for 24h to increase the forming performance of the pug to obtain a mixture with the plasticity index of 11;

s7: and setting the preheating temperature to 400 ℃ according to the thermogravimetric curves of the sludge and the coal gangue. And (3) placing the dried blank into a sintering furnace, heating to the preheating temperature of 400 ℃ at the heating rate of 5 ℃/min, preserving the heat for 30min, heating to 950 ℃ at the heating rate of 5 ℃/min, preserving the heat for 1h at the highest temperature, and cooling along with the furnace.

The performance parameters of the obtained heat-insulating microporous brick are shown in a table 2.

Table 2 example 2 insulating microporous brick performance parameters

Example 3

s3: mixing 70%, 20% and 10% of shale particles, sludge particles and coal gangue particles in mass ratio after absolute dry mass conversion, grinding for 15-20min by a planetary ball mill, and sieving to obtain mixture powder; and after grinding, performing primary screening and secondary screening on the powder respectively in a 2mm sieve and a 0.2mm sieve, and weighing 4: placing the primary sieved powder and the secondary sieved powder in a stirrer according to the mass ratio of 6;

s4: weighing 0.5% of CMC powder based on the mass of the mixture, putting the CMC powder into a stirrer as a flocculating agent, stirring for 3min, taking out part of dry mixture powder, filling the mixture into a soil sample cup, leveling the cup mouth, weighing the plastic deformation capacity of the pug by the depth of a cone of a soil liquid plastic limit tester falling into the soil sample cup, when the depth is less than 6mm, continuously adding water until the depth is 6mm, and then taking out part of the pug, putting the pug into an oven, and drying to obtain the mixture with the molding water content of 26%. Weighing water accounting for 26% of the mass of the mixture at the moment according to the obtained water content, adding the water into a stirrer, stirring and mixing for 5min to obtain pug, then conveying the pug to a curing chamber with the relative humidity of more than 85%, and aging for 24h to increase the forming performance of the pug to obtain a mixture with the plasticity index of 15;

s7: and setting the preheating temperature to 450 ℃ according to the thermogravimetric curves of the sludge and the coal gangue. And (3) placing the dried blank into a sintering furnace, heating to the preheating temperature of 400 ℃ at the heating rate of 5 ℃/min, preserving the heat for 30min, heating to 950 ℃ at the heating rate of 5 ℃/min, preserving the heat for 1h at the highest temperature, and cooling along with the furnace.

The performance parameters of the obtained heat-insulating microporous brick are shown in a table 3.

Table 3 example 3 insulating microporous brick performance parameters

Claims

1. The sludge shale heat-insulation microporous brick is characterized by being prepared from the following raw materials in percentage by mass: according to absolute dry mass conversion, 70-75% of shale, 15-20% of sludge and 5-15% of coal gangue are added with sodium carboxymethylcellulose accounting for 0.5% of the total mass of the mixture;

the preparation method comprises the following steps:

(1) respectively crushing the dried sludge, shale and coal gangue in a crushing device to obtain granules, mixing the shale granules with 70-75 percent, the sludge granules with 15-20 percent and the coal gangue granules with 5-15 percent, then grinding and sieving to obtain mixture powder, wherein the sieving is to perform primary sieving and secondary sieving respectively through a 2mm sieve and a 0.2mm sieve, and the mass ratio of the powder after the primary sieving and the secondary sieving is 4: 6;

(2) adding sodium carboxymethylcellulose accounting for 0.5 percent of the total mass of the mixture into the mixture powder as a flocculating agent, adding water, stirring to prepare a pug, and putting the pug into a curing chamber for aging;

(4) placing the dried blank body into a sintering furnace for roasting to obtain a product;

controlling the plasticity index of the pug to be 10-17;

and (4) heating to the preheating temperature of 400-.

2. The preparation method of the sludge shale heat-insulating microporous brick is characterized by comprising the following steps:

controlling the plasticity index of the pug to be 10-17;

and (4) heating to the preheating temperature of 400-.

3. The method for preparing the sludge shale heat-insulating microporous brick as claimed in claim 2, wherein the crushing device in the step (1) is a jaw crusher, a hammer crusher or a fine crusher, and the particle size of the crushed particles is below 5 mm.

4. The method for preparing the sludge shale heat-insulating microporous brick according to claim 2, wherein the water adding amount is determined by the following method: adding water and stirring the mixture powder until the mixture powder shows plasticity from the powder, then filling the soil sample cup with the pug, leveling the cup mouth, measuring the plastic deformation capability of the pug by the depth of the cone of the soil liquid plastic limit tester dropping into the soil sample cup, and when the depth is less than 6mm, continuously adding water and stirring until the depth is 6 mm.

5. The method for preparing sludge shale insulating microporous brick as claimed in claim 2, wherein the step (2) of putting the sludge into a curing room with relative humidity of more than 85% and aging for 22-26 h.

6. The method for preparing sludge shale heat-insulating microporous bricks as claimed in claim 2, wherein the formed body in step (3) is dried at 35-45 ℃ for 1.5-2.5h, and then the drying temperature is raised to 100-110 ℃ for 3.5-4.5 h.