CN111943715A - Method for firing ceramsite based on modified sludge - Google Patents
Method for firing ceramsite based on modified sludge Download PDFInfo
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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
- C04B38/00—Porous mortars, concrete, artificial stone or ceramic ware; Preparation thereof
- C04B38/009—Porous or hollow ceramic granular materials, e.g. microballoons
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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
- C04B33/00—Clay-wares
- C04B33/02—Preparing or treating the raw materials individually or as batches
- C04B33/13—Compounding ingredients
- C04B33/131—Inorganic additives
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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
- C04B33/00—Clay-wares
- C04B33/02—Preparing or treating the raw materials individually or as batches
- C04B33/13—Compounding ingredients
- C04B33/132—Waste materials; Refuse; Residues
- C04B33/1321—Waste slurries, e.g. harbour sludge, industrial muds
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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
- C04B38/00—Porous mortars, concrete, artificial stone or ceramic ware; Preparation thereof
- C04B38/02—Porous mortars, concrete, artificial stone or ceramic ware; Preparation thereof by adding chemical blowing agents
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P40/00—Technologies relating to the processing of minerals
- Y02P40/60—Production of ceramic materials or ceramic elements, e.g. substitution of clay or shale by alternative raw materials, e.g. ashes
Abstract
The invention provides a method for firing ceramsite based on modified sludge, which comprises the following specific steps: (1) the modified material comprises the following raw materials in percentage by weight: 50-60% of blast furnace slag, 20-30% of fly ash, 12-17% of quick lime, 2-6% of sodium bicarbonate and 1-2% of gypsum; (2) uniformly mixing the raw materials in proportion, and grinding for 3-5 min; (3) the modified sludge comprises the following raw materials in parts by weight: 80-85 parts of dewatered sludge and 15-20 parts of modified materials; (4) mixing and granulating; (5) standing the material ball particles at normal temperature for 1-3d for modification; (6) firing at high temperature; according to the invention, clay is completely replaced by industrial byproducts, the generation of unstable factors such as heavy metal dissolution is reduced, and no foaming agent is required to be added, so that the physical and chemical properties of the sludge are improved to a certain extent after the ingredients are mixed, the modification process is used for replacing pre-burning and roasting, the requirements on a raw material yard are reduced, and the energy waste in the pre-burning and roasting process is reduced.
Description
Technical Field
The invention relates to the technical field of solid waste treatment and recycling, in particular to a method for firing ceramsite based on modified sludge.
Background
At present, the yield of municipal excess sludge produced in China every year exceeds 6000 million tons (the water content is calculated according to 80%), the sludge is an extremely complex heterogeneous body consisting of organic residues, bacterial thalli, inorganic particles, colloids and the like, the disposal mode of the sludge at present mainly comprises landfill, composting, brick firing and the like, secondary pollution is caused to the environment, and the sludge is also extremely harmful to the health of human bodies, and the sludge is used as a main raw material to prepare ceramsite, so that the harmless treatment of the sludge is realized, and considerable economic benefits are realized.
At present, the ceramsite industry in China is not only the traditional industry, but also the sunward industry, has become a leading force for digesting solid wastes such as sludge, and the like, but still has a great number of problems, and the main problems are as follows:
(1) china still takes clay ceramsite as a main material, the existing research uses partial sludge to replace clay but the sludge mixing amount is small, the sludge is not used as a main sintering raw material, and the sintered ceramsite has the problem that heavy metals are likely to be dissolved out when in use: such problems occur in patents such as "a method for firing clay ceramsite by using biological sludge of sewage treatment plant" with publication number CN1367156, "a method for preparing ceramsite by using sludge of municipal sewage plant" with publication number CN101148346, "a method for preparing light ceramsite by using sludge of municipal sewage plant" with publication number CN101386526, etc.;
(2) the energy consumption in the production process is overlarge, the process equipment is rough and simple, a two-section or multi-section sintering process combining pre-sintering and roasting is generally adopted, the product quality is uneven, the variety is single, and the energy waste and the operation are complicated, for example, the problems appear in patents of 'a preparation method of ceramsite by taking municipal sludge as a raw material' with the publication number of CN107216126A, 'a method for preparing ceramsite by sintering municipal domestic sewage sludge with the publication number of CN 101148348', 'a method for preparing ceramsite by utilizing activated sludge' with the publication number of CN108821780A, and 'a method for preparing light ceramsite by using sludge of a water supply plant and a sewage plant' with the publication number of CN 1644565;
(3) the production method of the sludge ceramsite has the problems that the sludge and the ingredients are uniformly mixed according to a certain proportion, and after the sludge ceramsite is prepared by adopting a drying method, various raw materials are mixed by adding water according to a certain proportion, so that the waste of resources is caused, the complete and uniform mixing is difficult to achieve, the product quality is influenced, and the resource recovery purpose is not fully embodied, for example, the problems appear in the patents with the publication number of CN103130489A, such as ' a technology for preparing the ceramsite by utilizing the sludge of a sewage plant ', the publication number of CN108821780A, a method for preparing the ceramsite by utilizing the activated sludge ', the publication number of CN102731055A, and the like;
(4) in addition, in the prior art, temperature control in stages of drying, pre-burning, roasting and the like does not avoid a temperature generation area of a highly toxic substance dioxin, part of smoke has long retention time, a smoke treatment device is single and laggard, and clean production does not reach the standard, and such problems occur in patents such as ' a method for preparing light porous ceramsite by using municipal sewage sludge ', a method for firing ceramsite by using activated sludge ', and the like, wherein the patents are CN106995306A, and CN 108821780A.
(5) Although some technologies use slag, steel slag, fly ash, quicklime, gypsum and other industrial waste residues and sludge to prepare non-sintered ceramsite, cement and other cementing materials and fly ash, slag and other auxiliary cementing materials with latent hydraulicity are mainly used for hardening the sludge to generate certain strength, so that the utilization rate of the sludge is low, the content of the sludge is generally below 10%, and the natural curing period is long, such as the patent of CN106966621A, namely a method for preparing non-sintered ceramsite by using electroplating sludge, and the like, have the problems.
Disclosure of Invention
The invention aims to provide a method for firing ceramsite based on modified sludge, which can greatly improve the heavy metal stabilization effect, reduce energy consumption and resource waste and can fire high-quality ceramsite.
In order to solve the technical problems, the technical scheme adopted by the invention is as follows:
a method for firing ceramsite based on modified sludge comprises the following specific steps:
(1) the modified material comprises the following components: blast furnace slag, fly ash, quick lime, sodium bicarbonate and gypsum are selected as raw materials of the modified material, and the weight percentage of each raw material is as follows: 50-60% of blast furnace slag, 20-30% of fly ash, 12-17% of quick lime, 2-6% of sodium bicarbonate and 1-2% of gypsum;
(2) preparing a modified material: uniformly mixing the raw materials in the step (1) in proportion, and grinding to obtain a modified material;
(3) the modified sludge comprises the following components: the method comprises the following steps of (1) selecting dewatered sludge with the water content of 75-85% generated by a sewage treatment plant and the modified material prepared in the step (2) as raw materials, and taking the raw materials according to the following weight part ratio: 80-85 parts of dewatered sludge and 15-20 parts of modified materials;
(4) mixing and granulating: uniformly mixing and stirring the raw materials in the step (3), and putting the stirred materials into a granulator for granulation to obtain material ball particles;
(5) standing modification: placing the material ball particles at normal temperature and standing for 1-3d for modification;
(6) and (3) high-temperature firing: and heating the mixture to 1200-1280 ℃ from room temperature at the speed of 15-20 ℃/min in an incinerator, and firing the modified pellets to obtain the ceramsite.
Further, the grinding time in the step (2) is 3-5 min.
Further, the specific surface area of the modified material prepared in the step (2) is 3400-3600 cm2/g。
Further, the water content of the dewatered sludge selected in the step (3) is 80%.
Further, the water content of the sludge modified in the step (5) is reduced to 45-55%.
Further, the sludge property modified in the step (5) is changed from black paste glue substances into odorless clay-like materials.
Further, the firing time in the step (6) is 20-25 min.
Further onThe weight loss ratio of the ceramsite prepared in the step (6) is 65-75%, and the bulk density is 450-600 kg/m3The water absorption rate is 4.5-12.5%, and the cylinder pressure strength is 1.5-2.8 MPa.
Wherein the sludge modification reaction mechanism is as follows:
in the invention, when industrial waste residues such as blast furnace slag, fly ash and the like are contacted with water in sludge under an alkaline condition, a series of hydration reactions can be carried out with free water and interstitial water in the sludge to generate hydration products such as insoluble calcium silicate hydrate (C-S-H) gel, ettringite (AFt) crystal and the like, so that part of water in the sludge is converted into mineral crystal water, and part of water is removed due to the fact that the temperature is increased because of heat released by the hydration reactions, and finally the water content of the modified sludge is reduced to 45-55%. The hydration products such as C-S-H gel, AFt crystal and the like are mutually overlapped and tightly combined with the solid particles in the sludge, so that the loose and aggregated structural system of the original sludge is thoroughly changed, and all phases in the modified sludge are firmly bonded into a whole. The sludge property can be changed from black paste gum material to odorless clay material, the property is stable, the cohesiveness is increased, the sludge is easy to extend, and the SiO is2、Al2O3、Fe2O3And the content of inorganic matters is increased, so that a framework structure is provided for firing the ceramsite.
CaO+H2O＝Ca(OH)2
2CaO·SiO2+mH2O→xCaO·SiO2·yH2O+(2-x)Ca(OH)2
3CaO·SiO2+mH2O→xCaO·SiO2·yH2O+(3-x)Ca(OH)2
3CaO·Al2O3+3(CaSO4·2H2O)+26H2O→3CaO·Al2O3·CaSO4·32H2O
The hydration reaction process of the industrial waste residue such as blast furnace slag, fly ash and the like is as follows:
(1) hydration of quicklime (CaO) to produce Ca (OH)2Forming a water film on the surface of industrial slag particles such as blast furnace slag, fly ash and the like;
(2)Ca(OH)2forming alkaline film solution on the surface of slag particles of blast furnace slag, fly ash and the like through crystallization, and hydrolyzing gypsum to provide Ca2+And SO4 2-；
(3) The surfaces of waste slag particles such as blast furnace slag, fly ash and the like are corroded by the alkaline film solution, and volcanic ash reaction is carried out to generate partial C-S-H gel and AFt crystals;
(4) as the modification time is prolonged, the water is continuously supplied, and the alkaline film solution continues to exist on the particle surface and further erodes the particle surface through hydrate gaps until the active mineral components in the waste residue are completely hydrated.
The reaction process of the foaming agent is as follows:
ca (OH) produced by reaction of sodium bicarbonate and quicklime with water2The reaction is carried out to obtain by-product limestone, and the limestone generates CO in the process of firing the ceramsite at high temperature2A gas. The following reactions occur:
NaHCO3+Ca(OH)2＝CaCO3↓+NaOH+H2O
CaCO3＝CaO+CO2↓ (high temperature 900 ℃ calcination)
The organic component in the sludge is mainly a carbon-containing organic matter and can also be used as a carbon source for expansion of the ceramsite so as to generate gas reaction with the ferric oxide.
2Fe2O3+3C＝4Fe+3CO2↓ (high temperature)
At the same time, the organic matter produces small molecule gaseous matter, such as CO, during high temperature roasting2、CO、H2O, and the like.
Reasons for the reduction in heavy metal dissolution:
after modification, the forms of heavy metals such as Zn, Cr, Cu, Pb, Ag, Cd and the like in the sludge are changed to a certain extent, wherein the residue states are increased to different degrees. The main reason is that the acid soluble heavy metal with strong migration capacity and reducible and oxidizable heavy metals with potential migration capacity are converted into inert residue heavy metal by the functions of percolation, evaporation, hydration reaction and the like in the modification process of the sludge, so that the effect of stabilizing the heavy metals in the sludge is achieved. Meanwhile, with the increase of the hydration degree, the structure of the hydration product is more compact, the structural stability is greatly improved, the leaching concentration of the solidified heavy metal elements is greatly reduced, and the stabilization effect of the heavy metal is improved.
The invention has the beneficial effects that:
1. firstly, mixing and stirring dewatered sludge with the water content of 75-85% by taking an industrial byproduct mainly comprising blast furnace slag as an ingredient, adding the mixture into a granulator for granulation, and completely replacing clay by the industrial byproduct to reduce the generation of unstable factors such as heavy metal dissolution; the foaming agent can be generated spontaneously in the preparation process, and the foaming agent can be added without any other additive, so that the foaming agent can be favorable for internal chemical reaction to release gas, generate air holes to expand, and reduce the density of the ceramsite, thereby forming a closed porous structure inside, reducing the cost and saving the energy.
2. The invention modifies the granulated material ball particles by standing for 1-3 days at normal temperature, avoids the operations of drying, adding water for mixing and the like, and simultaneously improves the physical and chemical properties of the sludge to a certain extent after the ingredients are mixed, namely: stabilize poisonous and harmful substances such as heavy metals and the like in the sludge, reduce the water content of the sludge from about 80% to 45-55%, convert the sludge into clay-like substances to improve the cohesiveness of the sludge, and facilitate extension of the sludge, wherein SiO is used as a material for preparing the clay-like substances2、Al2O3、Fe2O3Etc. and the content of inorganic matters is increased, and physical pollution such as malodor and the like is not generated any more.
3. The modified sludge is used as a raw material, the temperature is increased from room temperature to 1200-1280 ℃ at the speed of 15-20 ℃/min for high-temperature firing for 20-25 min, and the modification process is used for replacing pre-sintering and roasting, so that the requirements on a raw material yard are reduced, the energy waste in the pre-sintering and roasting process is reduced, two-stage or multi-stage sintering is avoided, the clay usage amount in the manufacturing process is saved, and the resource, harmless and stable treatment is better achieved.
4. The fired ceramsite has the weight loss ratio of 65-75% and the bulk density of 450-600 kg/m3The water absorption rate is 4.5-12.5%, and the cylinder pressure strength is1.5-2.8 Mpa, and the physical properties of the aggregate accord with the national standard GB/T17431.1-2010 lightweight aggregate and the test method thereof. The ceramsite has smooth surface, red brown enamel and good hardness and macroporosity, and is a high-quality sludge ceramsite.
Drawings
FIG. 1 is a block diagram of the process flow of the present invention.
FIG. 2 is a sample of ceramic particles fired based on modified sludge according to the present invention.
Detailed Description
The invention is further illustrated by the following examples.
Example 1:
a method for firing ceramsite based on modified sludge comprises the following specific steps:
(1) the modified material comprises the following components: blast furnace slag, fly ash, quick lime, sodium bicarbonate and gypsum are selected as raw materials of the modified material, and the weight percentage of each raw material is as follows: 55% of blast furnace slag, 25% of fly ash, 15% of quicklime, 4% of sodium bicarbonate and 1% of gypsum;
(2) preparing a modified material: uniformly mixing the raw materials in the step (1) in proportion, and grinding for 3-5 min, preferably for 3min to prepare the modified material, wherein the specific surface area of the modified material is 3400-3600 cm2The range of the/g meets the requirements of the invention;
(3) the modified sludge comprises the following components: selecting dewatered sludge with the water content of 75-85%, preferably 80% generated by a certain sewage treatment plant in Zhengzhou city and the modified material prepared in the step (2) as raw materials, and taking the raw materials according to the following weight part ratio: 85 parts of dehydrated sludge and 15 parts of modified materials;
(4) mixing and granulating: uniformly mixing and stirring the raw materials in the step (3), and putting the stirred materials into a granulator for granulation to obtain material ball particles;
(5) standing modification: placing the pellet particles at normal temperature and standing for 1-3d, preferably 3d, modifying, wherein the water content of the modified sludge is reduced to 45-55%, the modified sludge meets the requirements of the invention, and the properties of the modified sludge are changed from black paste rubber substances into odorless clay-like materials;
(6) and (3) high-temperature firing: and (3) heating the mixture from room temperature to 1200-1280 ℃ and preferably 1250 ℃ at the speed of 15-20 ℃/min, preferably 20 ℃/min, in an incinerator, and firing the modified pellets for 20-25 min, preferably 20min to obtain the ceramsite.
Example 2:
a method for firing ceramsite based on modified sludge comprises the following specific steps:
(1) the modified material comprises the following components: blast furnace slag, fly ash, quick lime, sodium bicarbonate and gypsum are selected as raw materials of the modified material, and the weight percentage of each raw material is as follows: 60% of blast furnace slag, 20% of fly ash, 12% of quicklime, 6% of sodium bicarbonate and 2% of gypsum;
(2) preparing a modified material: uniformly mixing the raw materials in the step (1) in proportion, and grinding for 3-5 min, preferably for 3min to obtain a modified material;
(3) the modified sludge comprises the following components: selecting dewatered sludge with the water content of 75-85%, preferably 80% generated by a certain sewage treatment plant in Zhengzhou city and the modified material prepared in the step (2) as raw materials, and taking the raw materials according to the following weight part ratio: 85 parts of dehydrated sludge and 15 parts of modified materials;
(4) mixing and granulating: uniformly mixing and stirring the raw materials in the step (3), and putting the stirred materials into a granulator for granulation to obtain material ball particles;
(5) standing modification: placing the pellet particles at normal temperature for standing for 1-3d, preferably 3d, and modifying;
(6) and (3) high-temperature firing: and (3) heating the mixture from room temperature to 1200-1280 ℃ and preferably 1250 ℃ at the speed of 15-20 ℃/min, preferably 20 ℃/min, in an incinerator, and firing the modified pellets for 20-25 min, preferably 20min to obtain the ceramsite.
Example 3:
a method for firing ceramsite based on modified sludge comprises the following specific steps:
(1) the modified material comprises the following components: blast furnace slag, fly ash, quick lime, sodium bicarbonate and gypsum are selected as raw materials of the modified material, and the weight percentage of each raw material is as follows: 50% of blast furnace slag, 30% of fly ash, 17% of quicklime, 2% of sodium bicarbonate and 1% of gypsum;
(2) preparing a modified material: uniformly mixing the raw materials in the step (1) in proportion, and grinding for 3-5 min, preferably for 3min to obtain a modified material;
(3) the modified sludge comprises the following components: selecting dewatered sludge with the water content of 75-85%, preferably 80% generated by a certain sewage treatment plant in Zhengzhou city and the modified material prepared in the step (2) as raw materials, and taking the raw materials according to the following weight part ratio: 80 parts of dehydrated sludge and 20 parts of modified materials;
(4) mixing and granulating: uniformly mixing and stirring the raw materials in the step (3), and putting the stirred materials into a granulator for granulation to obtain material ball particles;
(5) standing modification: placing the pellet particles at normal temperature for standing for 1-3d, preferably 3d, and modifying;
(6) and (3) high-temperature firing: and (3) heating the mixture from room temperature to 1200-1280 ℃ and preferably 1250 ℃ at the speed of 15-20 ℃/min, preferably 20 ℃/min, in an incinerator, and firing the modified pellets for 20-25 min, preferably 20min to obtain the ceramsite.
Example 4:
a method for firing sludge into ceramsite comprises the following specific steps:
(1) the method comprises the following steps of selecting dewatered sludge with the water content of 75-85%, preferably 80% generated by a certain sewage treatment plant in Zhengzhou city as a raw material, and taking the raw materials according to the following weight part ratio: 85 parts of dehydrated sludge and 15 parts of clay;
(2) uniformly mixing and stirring the raw materials in the step (1), and putting the stirred materials into a granulator for granulation to obtain material ball particles;
(3) placing the pellet particles at normal temperature for standing for 1-3d, preferably 3 d;
(4) and (3) heating the mixture to 1200-1280 ℃ from room temperature at the speed of 15-20 ℃/min, preferably 20 ℃/min, in an incinerator, preferably 1250 ℃, and firing the pellets for 20-25 min, preferably 20min to obtain the ceramsite.
Example 5:
a method for firing sludge into ceramsite comprises the following specific steps:
(1) the modified material comprises the following components: blast furnace slag, fly ash, quick lime, sodium bicarbonate and gypsum are selected as raw materials of the modified material, and the weight percentage of each raw material is as follows: 55% of blast furnace slag, 25% of fly ash, 15% of quicklime, 4% of sodium bicarbonate and 1% of gypsum;
(2) preparing a modified material: uniformly mixing the raw materials in the step (1) in proportion, and grinding for 3-5 min, preferably for 3min to obtain a modified material;
(3) the modified sludge comprises the following components: selecting dewatered sludge with the water content of 75-85%, preferably 80% generated by a certain sewage treatment plant in Zhengzhou city and the modified material prepared in the step (2) as raw materials, and taking the raw materials according to the following weight part ratio: 85 parts of dehydrated sludge and 15 parts of modified materials;
(4) mixing and granulating: uniformly mixing and stirring the raw materials in the step (3), and putting the stirred materials into a granulator for granulation to obtain material ball particles;
(5) and (3) high-temperature firing: and (3) heating the mixture from room temperature to 1200-1280 ℃ and preferably 1250 ℃ at the speed of 15-20 ℃/min, preferably 20 ℃/min, in an incinerator, and firing the modified pellets for 20-25 min, preferably 20min to obtain the ceramsite.
And (3) performance test results:
the properties of the ceramsite prepared according to the examples 1-5 are specifically shown in Table 1.
From the above table, it can be seen that the modified material and the standing modification process both have important influence on the performance and quality of the ceramsite:
(1) whether the modified material is adopted or not has a remarkable influence on the quality of the ceramsite.
Compared with the example 1, in the example 4, when clay is used instead of the modifying material, the ceramic particle strength is reduced due to more surface cracks and internal pores in the firing process of the ceramic particle, and the bulk density is greatly reduced and the water absorption is greatly increased.
(2) Omitting the standing modification process can affect the quality of the ceramsite.
Compared with the example 1, in the example 5, when the standing modification process is omitted, the hydration reaction between the modified material and the sludge is not sufficiently generated, so that the water content of the modified sludge is not reduced to a proper range, the raw material is not completely melted into a liquid phase in the process of firing the ceramsite, the internal structure of the ceramsite is loose, the gas released from the inside of the raw material can not be sealed, and the bulk density and the cylinder pressure strength are reduced.
In summary, in the invention, firstly, the industrial byproduct mainly comprising blast furnace slag is added as an ingredient to mix and stir the dewatered sludge with the water content of 80 percent, and the mixture is added into a granulator for granulation, so that the sludge and the industrial byproduct completely replace clay, and the generation of unstable factors such as heavy metal dissolution is reduced; and then standing for 1-3d at normal temperature to modify the sludge, avoiding operations such as drying, adding water for mixing and the like, and simultaneously improving the physical and chemical properties of the sludge to a certain extent after the ingredients are mixed, namely: stabilizing toxic and harmful substances such as heavy metals and the like in the sludge, reducing the water content of the sludge from 80% to 45-55% (optimizing sludge components, coordinating the proportional problems of silicon dioxide, calcium oxide and the like in the sludge, reducing the possibility of burning and swelling), converting the sludge into clay-like substances to improve the cohesiveness of the sludge, and facilitating extension of the sludge, wherein SiO is used as a material for the sludge2、Al2O3、Fe2O3The content of inorganic substances is increased, and physical pollution such as odor is not generated; and then taking the modified sludge as a raw material, heating the raw material from room temperature to 1250 ℃ at the speed of 20 ℃/min, and carrying out high-temperature firing for 20min, replacing pre-sintering and firing with the modification process, so that the requirements on a raw material yard are reduced, the energy waste in the pre-sintering and firing processes is reduced, two-stage or multi-stage sintering is avoided, the clay usage amount in the manufacturing process is saved, and the resource, harmless and stable treatment is better achieved.
Claims (9)
1. A method for firing ceramsite based on modified sludge is characterized by comprising the following specific steps:
(1) the modified material comprises the following components: blast furnace slag, fly ash, quick lime, sodium bicarbonate and gypsum are selected as raw materials of the modified material, and the weight percentage of each raw material is as follows: 50-60% of blast furnace slag, 20-30% of fly ash, 12-17% of quick lime, 2-6% of sodium bicarbonate and 1-2% of gypsum;
(2) preparing a modified material: uniformly mixing the raw materials in the step (1) in proportion, and grinding to obtain a modified material;
(3) the modified sludge comprises the following components: the method comprises the following steps of (1) selecting dewatered sludge with the water content of 75-85% generated by a sewage treatment plant and the modified material prepared in the step (2) as raw materials, and taking the raw materials according to the following weight part ratio: 80-85 parts of dewatered sludge and 15-20 parts of modified materials;
(4) mixing and granulating: uniformly mixing and stirring the raw materials in the step (3), and putting the stirred materials into a granulator for granulation to obtain material ball particles;
(5) standing modification: placing the material ball particles at normal temperature and standing for 1-3d for modification;
(6) and (3) high-temperature firing: 15 to 20% in an incineratoroThe temperature of the C/min is increased from room temperature to 1200-1280oAnd C, firing the modified pellets to obtain the ceramsite.
2. The method for firing ceramsite based on modified sludge as recited in claim 1, wherein: and (3) grinding time in the step (2) is 3-5 min.
3. The method for firing ceramsite based on modified sludge as recited in claim 1, wherein: the specific surface area of the modified material prepared in the step (2) is 3400-3600 cm2/g。
4. The method for firing ceramsite based on modified sludge as recited in claim 1, wherein: the water content of the dewatered sludge selected in the step (3) is 80%.
5. The method for firing ceramsite based on modified sludge as recited in claim 1, wherein: and (4) reducing the water content of the sludge modified in the step (5) to 45-55%.
6. The method for firing ceramsite based on modified sludge as recited in claim 1, wherein: the sludge property modified by the step (5) is changed from black paste glue substances into odorless clay-like materials.
7. The method for firing ceramsite based on modified sludge as recited in claim 1, wherein: the firing time in the step (6) is 20-25 min.
8. The method for firing ceramsite based on modified sludge as recited in claim 1, wherein: the weight loss ratio of the ceramsite prepared in the step (6) is 65-75%, and the bulk density is 450-600 kg/m3The water absorption rate is 4.5-12.5%, and the cylinder pressure strength is 1.5-2.8 MPa.
9. Ceramsite produced according to any one of the preceding claims 1 to 8.
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| CN115368043A (en) * | 2022-08-22 | 2022-11-22 | 深圳市衡骏环保科技有限公司 | Recycled lightweight aggregate based on washed sand bottom mud and preparation method thereof |
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