CN114716173A - Circulating fluidized bed slag resource utilization method - Google Patents
Circulating fluidized bed slag resource utilization method Download PDFInfo
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- CN114716173A CN114716173A CN202210446840.5A CN202210446840A CN114716173A CN 114716173 A CN114716173 A CN 114716173A CN 202210446840 A CN202210446840 A CN 202210446840A CN 114716173 A CN114716173 A CN 114716173A
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- slag
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- concrete
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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
- C04B40/00—Processes, in general, for influencing or modifying the properties of mortars, concrete or artificial stone compositions, e.g. their setting or hardening ability
- C04B40/0028—Aspects relating to the mixing step of the mortar preparation
- C04B40/0039—Premixtures of ingredients
- C04B40/0046—Premixtures of ingredients characterised by their processing, e.g. sequence of mixing the ingredients when preparing the premixtures
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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
- Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
- Y02W30/00—Technologies for solid waste management
- Y02W30/50—Reuse, recycling or recovery technologies
- Y02W30/91—Use of waste materials as fillers for mortars or concrete
Abstract
The invention discloses a resource utilization method of circulating fluidized bed slag (CFB slag) in the field of concrete. The method specifically comprises the following steps: 1) sorting CFB slag into fine grain slag with the grain size smaller than 0.6mm and coarse grain slag with the grain size larger than or equal to 0.6 mm; 2) mixing fine-grain slag with the grain size smaller than 0.6mm with auxiliary materials, and then grinding to prepare an expanding agent; and replacing part of concrete fine aggregates with coarse-grained slag with the grain size of more than or equal to 0.6mm for preparing concrete. The method effectively separates the characteristics of high calcium and sulfur content of the CFB slag and the characteristics of the CFB slag capable of being used for concrete aggregate by a simple method, thereby not only avoiding the adverse effect of the high calcium and sulfur content in the slag on concrete, but also fully utilizing the characteristic of the high calcium and sulfur content of the slag, obviously improving the resource utilization rate of the CFB slag and having important environmental protection value and economic benefit.
Description
Technical Field
The invention belongs to the field of resource utilization of industrial solid wastes, and particularly relates to a resource utilization method of coal-fired furnace slag of a circulating fluidized bed in the field of concrete.
Background
Circulating fluidized bed combustion slag, CFB slag for short, is particulate solid waste discharged from the bottom of a circulating fluidized bed boiler after coal is combusted in the boiler. The building material industry is an important path for utilizing industrial solid waste, but the chemical components of CFB slag discharged by a special desulfurization technology during the combustion of a circulating fluidized bed boiler are mainly SiO2、Al2O3、SO3And CaO mainly. Therefore, the CFB slag has high calcium and sulfur content and has the characteristics of volcanic ash activity and the like. In the current research, CFB slag is mainly ground by mechanical equipment and then used as a concrete admixture, but the CFB slag generates hydration products such as ettringite and the like when being applied due to high calcium and sulfur content, so that the expansion and cracking problems are caused, the doping amount of the CFB slag is usually not more than 20% when being used, the utilization rate is always low, and how to improve the CFB through a simple method to improve the utilization rate of the slag is urgent.
Disclosure of Invention
The invention aims to provide an efficient and targeted circulating fluidized bed slag grading resource utilization method, which effectively separates the characteristics of high calcium and sulfur content of CFB slag and the characteristics of being used for concrete aggregate by a simple method, avoids the adverse effect of the high calcium and sulfur content of the slag on concrete, fully utilizes the characteristic of the high calcium and sulfur content of the slag, obviously improves the resource utilization rate of the CFB slag, and has important environmental protection value and economic benefit.
In order to solve the technical problems, the invention adopts the following technical scheme:
the method for recycling the slag of the circulating fluidized bed comprises the following steps:
1) sorting CFB slag into fine grain slag with the grain size smaller than 0.6mm and coarse grain slag with the grain size larger than or equal to 0.6 mm;
2) mixing fine-grain slag with the grain size smaller than 0.6mm with auxiliary materials, and then grinding to prepare an expanding agent; and replacing part of concrete fine aggregates with coarse-grained slag with the grain size of more than or equal to 0.6mm for preparing concrete.
According to the scheme, the CFB slag is solid waste discharged from the bottom of the circulating fluidized bed boiler of the coal-fired power plant.
According to the scheme, the primary particle size range of the CFB slag is 0-4.75 mm.
According to the scheme, the CaO content in the CFB slag is not lower than 5.0%, and SO is not lower than3The content is not less than 3.0%.
According to the scheme, in the step 1), the primary separation is to sieve through a sieve hole with 0.6mm, and the particle size of the CFB slag is divided into two particles with particle size ranges.
According to the scheme, in the step 2), the mass percent of the CFB slag in the expanding agent is 40-70%.
According to the scheme, in the step 2), the auxiliary material is one or any combination of gypsum materials, lime materials, magnesium materials, silicon-aluminum materials and the like.
Preferably, the gypsum-based material is one of anhydrous gypsum, dihydrate gypsum, desulfurized gypsum, CFB fly ash, or any combination thereof.
Preferably, the lime-based material is one of quicklime, slaked lime, magnesium lime or any combination thereof.
Preferably, the magnesium material is one of magnesium oxide, magnesium sulfate, magnesium chloride or any combination thereof.
Preferably, the silica-alumina material is one of silica fume, mineral powder, fly ash and CFB fly ash or any combination thereof.
According to the scheme, in the step 2), the grinding is to grind and refine the mixture of the CFB slag and the auxiliary material by using grinding equipment such as a ball mill, a vibration mill or a vertical mill.
According to the scheme, in the step 2), the specific material surface area of the obtained expanding agent after grinding is not less than 200m2/kg。
According to the scheme, in the step 2), 50-70% of concrete fine aggregate is replaced by coarse-grained slag with the thickness of not less than 0.6 mm.
According to the scheme, in the step 2), the step of replacing part of the concrete fine aggregate with coarse-grained slag with the grain size of not less than 0.6mm specifically comprises the following steps: and (3) recleaning coarse-grained slag with the grain size of more than or equal to 0.6mm into particles with the grain size range of three grades, namely 0.6-1.18mm, 1.18-2.36mm and 2.36-4.75mm, and then mixing the particles with concrete fine aggregate to adjust the fineness modulus to obtain the mixed fine aggregate with the target gradation.
The invention provides a resource utilization method of circulating fluidized bed slag in the field of concrete, which firstly determines that the slag is sorted by taking 0.6mm as a grain size dividing point to obtain fine grain slag less than 0.6mm and coarse grain slag more than or equal to 0.6 mm. Wherein:
on one hand, the obtained fine grain slag with the calcium and sulfur content of less than 0.6mm has high calcium and sulfur content, can be used for preparing an expanding agent, converts the defect of high calcium and sulfur content into an advantage characteristic for full utilization, has high mixing amount of the slag in the expanding agent, has more uniform distribution of calcium and sulfur components in the slag after separation, and can more easily cause the concrete to uniformly expand by the obtained expanding agent.
On the other hand, the obtained coarse grain slag with the grain size of more than or equal to 0.6mm has low content of calcium and sulfur, can directly replace part of fine aggregates to be used in concrete, does not have the problem of expansion and cracking caused by the easy generation of hydration products such as excessive ettringite and the like due to high content of calcium and sulfur, slightly improves the strength of the concrete, can realize the replacement of the fine aggregates by large mixing amount, obviously reduces the cost of the concrete, and has important environmental protection value and economic effect.
The invention has the following beneficial effects:
1. the invention provides a resource utilization method of circulating fluidized bed slag, which is characterized in that 0.6mm is selected as a grain size dividing point for sorting, so that the high calcium and sulfur content of CFB slag and the characteristic of being used for concrete aggregate are effectively separated, the CFB slag with high calcium and sulfur content and the CFB slag with low calcium and sulfur content are respectively obtained, the CFB slag with high calcium and sulfur content can be used for preparing an expanding agent, and the CFB slag with low calcium and sulfur content can realize the preparation of concrete by replacing concrete fine aggregate with large mixing amount, thereby not only avoiding the adverse effect of the high calcium and sulfur content in the slag on the concrete, but also fully utilizing the characteristic of the high calcium and sulfur content of the slag, and converting the characteristic from the disadvantage characteristic into the advantage characteristic; the characteristic separation is realized through simple sorting, and the specific resource utilization is carried out, so that the resource utilization rate of the CFB furnace slag is obviously improved.
2. The calcium and sulfur content in the fine grain size slag obtained by sorting is high, and the fine grain size slag can be used in a large mixing amount when the expanding agent is prepared; the coarse grain slag can also replace concrete fine aggregates with large doping amount due to low calcium and sulfur content, and the strength of the obtained concrete is also slightly improved; the CFB slag can effectively reduce the cost of the expanding agent and the concrete, and has important environmental protection value and economic effect.
Detailed Description
The invention is further illustrated by the following specific examples.
Example 1
The original CFB slag used in this example had a chemical composition of 7.33% CaO and SO3The content is 6.19%; the particle size distribution is shown in table 1 below:
TABLE 1
| Particle size | <0.6 | 0.6-1.18 | 1.18-2.36 | 2.36-4.75 |
| CFB slag | 39.71 | 19.43 | 23.04 | 17.82 |
1) Preliminary sorting
Sorting through a 0.6mm sieve mesh to obtain CFB slag with the grain diameter of less than 0.6mm, wherein the CaO content is 13.57 percent, and the SO content is 13.57 percent3The content is 12.62%; CFB slag with grain size of more than 0.6mm, CaO content of 3.22%, and SO content3The content was 1.95%.
2) Preparation of swelling agent
The expanding agent comprises the following components in parts by weight: 60 parts of CFB furnace slag with the grain diameter smaller than 0.6mm, 20 parts of anhydrite, 10 parts of quicklime and 10 parts of CFB fly ash. Mixing the above raw materials, and grinding for 30min by using a ball mill to obtain the concrete expanding agent.
Wherein the specific surface area of the obtained expanding agent is 450kg/m2The result of mortar detection is as follows: the expansion rate of the mortar in water is limited to 0.052 percent in 7d, the expansion rate of the mortar in air is limited to-0.005 percent in 21d, the compressive strength of the mortar in 7d is 35.8MPa, and the compressive strength of the mortar in 28d is 47.4MPa, so that the requirements of GB23439-2017 are met.
3) Fine aggregate grading adjustment
CFB slag with the grain size of more than 0.6mm is classified into CFB slag with the grain size range of 0.6-1.18mm, 1.18-2.36mm and 2.36-4.75mm, and then the CFB slag is mixed into machine-made sand to carry out grading adjustment on the grain size, so that mixed fine aggregate with 2-zone grading is obtained, wherein the mixing amount of the CFB slag in the mixed fine aggregate is about 60 percent. The particle size distribution before and after the adjustment is shown in Table 2 below.
TABLE 2
Example 2
This example provides concrete based on CFB slag of 0.6mm or more obtained in example 1 mixed with machine-made sand fine aggregate, and comparative example with ordinary concrete, wherein the concrete formulation is shown in table 3 below:
TABLE 3
*: because the CFB furnace slag water absorption rate is higher than that of machine-made sand, the total water consumption of the concrete is slightly higher than that of the original concrete under the constant slump.
The two concrete compressive strength properties of the present embodiment are: the compressive strength of the original concrete 7d and 28d is 34.89MPa and 45.53MPa respectively; after adjustment, the compressive strengths of the CFB slag concrete 7d and 28d are respectively 35.42MPa and 47.91MPa, and the strength is slightly improved. The cost of the adjusted concrete is reduced by 52.3 yuan compared with the original concrete, and the method has better economic benefit.
Claims (10)
1. A recycling method of slag of a circulating fluidized bed is characterized by comprising the following steps:
1) sorting CFB slag into fine grain slag with the grain size smaller than 0.6mm and coarse grain slag with the grain size larger than or equal to 0.6 mm;
2) mixing fine-grain slag with the grain size smaller than 0.6mm with auxiliary materials, and then grinding to prepare an expanding agent; and replacing part of concrete fine aggregates with coarse-grained slag with the grain size of more than or equal to 0.6mm for preparing concrete.
2. The method of claim 1, wherein the CFB slag in step 1) has a primary particle size in the range of 0-4.75 mm.
3. The method according to claim 1, wherein in step 1), the content of CaO in the CFB slag is not less than 5.0%, and SO is not less than 5.0%3The content is not less than 3.0%.
4. The method according to claim 1, wherein in the step 2), the mass percentage of the CFB slag in the expanding agent is 40-70%.
5. The method according to claim 1, wherein in the step 2), the auxiliary material is one of gypsum-based material, lime-based material, magnesium-based material and silicon-aluminum-based material or any combination thereof.
6. The method of claim 5,
the gypsum material is one or any combination of anhydrous gypsum, dihydrate gypsum, desulfurized gypsum and CFB fly ash;
the lime material is one or any combination of quicklime, hydrated lime and magnesium lime;
the magnesium material is one or any combination of magnesium oxide, magnesium sulfate and magnesium chloride;
the silica-alumina material is one or any combination of silica fume, mineral powder, fly ash and CFB fly ash.
7. The method according to claim 1, wherein in the step 2), the grinding is performed by performing grinding and refining treatment on the mixture of the CFB slag and the auxiliary material by using a ball mill, a vibration mill or a vertical mill.
8. The method according to claim 1, wherein in the step 2), the specific material surface area of the obtained expanding agent after grinding is not less than 200m2/kg。
9. The method according to claim 1, wherein in step 2), coarse-grained slag of not less than 0.6mm replaces 50-70% of the concrete fine aggregate.
10. The method according to claim 1, wherein in step 2), the replacement of part of the concrete fine aggregates by coarse-grained slag of not less than 0.6mm is specifically: and (3) recleaning coarse grain slag with the grain size of more than or equal to 0.6mm into particles with the grain size ranges of three grades, namely 0.6-1.18mm, 1.18-2.36mm and 2.36-4.75mm, and then adding concrete fine aggregate for fineness modulus adjustment to obtain the mixed fine aggregate with target gradation.
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