Firstly, the scientific comprehensive utilization and realistic position of fly ash in baking-free bricks and wall materials.
1, China's coal-based energy structure determines the comprehensive utilization of 300 million tons of fly ash every year, which is a long-term and urgent task. In recent ten years, building materials industry has been the main user of fly ash, accounting for 50 ~ 60% of the total utilization, while wall materials industry accounts for 80% of the utilization of building materials industry.
Therefore, baking-free brick and block products are the main ways to realize the value of fly ash.
2. The fly ash sintered hollow brick is not suitable for the national conditions of China.
As early as the Eighth Five-Year Plan, the Ninth Five-Year Plan and the Tenth Five-Year Plan, the state has always regarded the utilization of fly ash as an effective way to develop new wall materials. When making the Tenth Five-Year Plan, fly ash sintered hollow brick with high ash content, high strength and high thermal insulation performance (four highs) will be taken as the leading product for developing new wall materials during the Tenth Five-Year Plan period and even for a long time to come.
Many years' practice has proved that sintering hollow bricks with fly ash is not suitable for China. When making the 11th Five-Year Plan, we should extensively absorb the latest scientific and technological achievements and completely revise the original technology.
The reason is that with the increasing attention to environmental protection and the improvement of air quality requirements, people have to consider the secondary pollution of fly ash and coal gangue sintered bricks to the atmosphere.
Using fly ash to prepare internal combustion sintered brick, the main air pollutants are SO2 and greenhouse gases.
3. According to the investigation of SO3 and C contents in coarse ash or mixed ash discharged from 140 small and medium-sized power plants, the SO3 content below the average value is 0.98% (SO3 is 0% ~ 3% according to the standard); The carbon (C) content is 8% (at present, the carbon (C) content in coarse ash discharged by most small and medium-sized power plants is 5% ~ 12%, and the carbon (C) content in wet ash discharged is as high as 15% ~ 22%).
According to this calculation, the 1 fly ash sintered brick factory with an annual output of 50 million standard bricks and a content of 65% will emit 5 17.2 tons of S03 gas and 19 tons of S03 gas every year;
4. The autoclaved fly ash brick factory with 65% content of the same scale only emits 24.9 tons of S03 gas and 3300 tons of CO2 gas. It can be seen that the amount of SO _ 2 and SO _ 2 gas emitted by sintered bricks with the same fly ash content is 20.8 times and 5.8 times that of autoclaved bricks, respectively.
Autoclaved fly ash brick factory is much less harmful than fly ash sintered brick. However, the amounts of SO3 gas and CO2 gas discharged after burning coal for steam production are still the same.
In addition, the amount of steam required increases, and coal resources cannot meet the requirements of green, ecological and circular economy development.
5. Compared with the 1 ordinary solid clay brick factory with an annual output of 50 million pieces, the gas emissions of SO2 and CO2 are 96.6 tons and10.3 million tons respectively.
It can be seen that the SO _ 2 and CO _ 2 gas emitted by fly ash sintered brick is 5.4 times and 1.46 times higher than that of ordinary solid clay brick, respectively.
Especially for fly ash and coal gangue with high sulfur and high carbon, the sintering process is more serious than firing ordinary solid clay bricks. The greater the dosage, the more serious the pollution.
6. The building materials industry is a big coal-burning enterprise second only to the electric power industry, but there is no fully mature process device for controlling SO2 emission by flue gas desulfurization.
Therefore, we should implement the National Cleaner Production Promotion Law, control and reduce pollution from the source, change the past terminal pollution control mode, and realize the sustainable development of new wall materials.
Two, "five suggestions"-how to develop high-performance fly ash baking-free brick and its wall materials?
1. How to develop high-performance fly ash brick and its wall materials?
Develop high-performance fly ash bricks to avoid the "secondary pollution" of SO2 and CO2 emitted by the combustion of fly ash sintered bricks to the atmosphere.
Therefore, it is necessary to make good use of fly ash and develop new wall materials that can replace solid clay bricks in energy saving, soil saving and improving building functions. It is also necessary to implement the Cleaner Production Promotion Law and realize the true greening of the environmental protection industry.
Therefore, high-performance fly ash brick has more significant social and economic significance than general new wall materials.
A factory with an annual output of 50 million standard bricks can consume 30,000 to 50,000 tons of ash every year, that is, 654.38+00 standard bricks need to consume 654.38+00 to 654.38+02 tons of ash every year, which is the largest product among all new wall materials at present, and each factory can reduce SO2 emission by about 480 tons every year.
China still emits 300 million tons of fly ash every year, which wastes a lot of valuable fly ash resources due to unreasonable and unscientific application.
There are still/kloc-0,000,000 sintered brick factories in China, with a total production of about 500-700 billion clay bricks.
According to the above calculation, the patented production technology of high-performance baking-free brick in Xinghua Village of China can be popularized in the whole country, and its economic and social benefits of energy saving, electricity saving and land resource saving are enormous astronomical figures.
2. At present, vibration molding equipment for concrete baking-free bricks and blocks is widely used in China, and the content of fly ash should not be too high, generally not more than 40%.
This is because fly ash is light and soft, and contains a lot of air. Through vibration molding, heavy mineral particles such as sand aggregate, aggregate and tricalcium silicate in cement with heavy specific gravity will sink, while fly ash and fly ash with light specific gravity will float on the surface, resulting in delamination, segregation, bleeding, pulverization and alkalization of materials at the upper, middle and lower levels, resulting in insufficient hydration of brick mineral particles and decreased strength of finished products.
If the content of fly ash exceeds 40%, the water demand is too high, and the water molecules between every two mineral particles combine and dry and evaporate, leaving more gaps, which is an important reason for the cracks on the brick surface and poor deep compactness of the brick.
3. The scientific laws of concrete baking-free bricks and block products (artificial cement stone) show that there are too many homogeneous materials and unbalanced mineral composition, which leads to supersaturation of some minerals and is not conducive to chemical bonding reaction.
The basic minerals of cement paste must have the chemical balance of four minerals: silicon, aluminum, iron and calcium.
"Chemical balance" is an eternal technical problem.
When the content of fly ash is too large, the main minerals brought into the brick body are silicon and aluminum, so there is a shortage of other minerals matching with it. Fundamentally speaking, it does not conform to the scientific laws of chemical equilibrium.
4. The scientific laws of concrete baking-free bricks and block products (artificial cement stone) also show that too many homogeneous materials increase many unfavorable factors affecting the durability of bricks.
If the content of fly ash is too much, that is to say, there are too many lightweight materials with high temperature and ultra-fine particles, which is not conducive to the rationality of "particle gradation" and "specific gravity gradation", so many unfavorable factors affecting the durability of brick bodies are added.
We should carefully consider the choice of brick-making equipment.
If the content of fly ash is deliberately increased, it is bound to increase the content of cement, improve the cement grade, or add inorganic or organic chemical products binder to meet the early strength requirements, which not only increases the cost, but also causes poor long-term durability, weather resistance and atmospheric stability, and the drying shrinkage and creep value will also increase.
Therefore, the selection of brick-making equipment should be carefully considered. Because, although vibration molding has many functions, it is not conducive to the stability and durability of the production quality of "load-bearing exterior wall baking-free brick". Not only the amount of fly ash is limited, but also the amount of cement and admixture will inevitably increase, and the production cost will also increase.
3. How to choose and produce baking-free brick equipment suitable for China's national conditions and people's practicality?
According to the current domestic industrial test and production practice, it is proved that advanced and reasonable pressing technology should be adopted to develop high-performance fly ash brick production equipment.
At present, many equipment manufacturers have developed this kind of brick-making equipment in addition to introducing foreign equipment.
The practice shows that the brick press with hydraulic fixed controllable pressurization program can meet the molding requirements of fly ash brick. In the pressurization procedure, the pressurization time can be automatically adjusted and the pressurization process can be controlled. The low-pressure preloading-slow pressurization-maintaining a constant molding pressure of about100t, and exhausting the air and water in the brick as much as possible, which is beneficial to the interactive superposition of various gradations and particles, so that the brick can achieve higher compactness and strength, thus ensuring the excellent performance of the product.
What needs to be reminded in particular here is that there is no mature brick pressing machine for fly ash residue abroad, and most of them are improved on the presses for molding lime-sand bricks, refractories or ceramic products. China is also in the trial production stage. Whether imported foreign equipment or domestic trial production, reasonable improvement and design are needed according to domestic raw materials such as fly ash and waste residue to meet the requirements.
The capacity of fly ash brick produced by this equipment can reach 1360 kg/m3, the strength is 10 ~ 30 MPa, the drying shrinkage is 0.26 ~ 0.30 mm/m, and the mass loss of freeze-thaw cycle is 0. 18% ~ 0.28%.
These technical properties not only exceed the performance indexes of building materials industry standard "Fly Ash Brick" and national standard "Sintered Ordinary Brick", but also are superior to sintered bricks with high content of fly ash. Especially, the low shrinkage performance is one of the lowest products among all wall materials at present, and the building performance such as thermal insulation, freeze-thaw cycle and so on is obviously superior to other products.
This kind of high-density unburned fly ash brick can not only be used for load-bearing structures, but also its strength can continue to increase in wet environment, especially suitable for places with wet underground foundations, such as building footholds, foundations and drainage ditches.
4. How to choose raw materials and batching technology for baking-free bricks and blocks?
The patent technology of Xinghua Village points out that it is necessary to fully promote the innovation and transformation of traditional materials and ingredients currently used in China.
For example, the selection of the following fly ash bricks exposes many technical misunderstandings.
Quality requirements of fly ash:
Chemical composition (%) SiO2-49, fe2o 3——0.36, Al2O3-14.41Cao-18.42, MgO—— 6.66, K2O-0.97, Na2O-65438.
The screen allowance (%) of the square hole screen with fineness of 0.08mm is not more than 12.5,
The loss on ignition is 5.89,
The dosage is 45-65%. Some even unilaterally increased to more than 80%.
Firstly, it is a kind of composition that does not conform to the law of mineral combination formation of baking-free brick, that is, artificial cement stone;
Second, this kind of products are shoddy, short in life, narrow in application field and too wasteful in resources;
Thirdly, it increases the amount of cement and admixture cementing materials, and cannot compete with traditional red bricks in the market.
Fourthly, the realistic and objective waste residue resources (fly ash) can not be fully utilized. Even if the waste residue that meets the quality requirements is used, there are still waste residues that cannot meet the quality and are difficult to reuse. It is necessary to find another way to recycle waste residue. Isn't it a waste of people and money after such a sorting cycle? This is not a scientific application.
It is called scientific brick making, that is to say, for all the waste residue resources on the earth, the first step is to extract a batch of "mineral additives" after people criticize these waste residue resources for production; In the second step, people use the waste materials not selected in the first step to produce cement; In the third step, most of the wastes not selected in the first and second steps are used to produce concrete. At this time, you will be picky about this residual waste, and you may choose many brick-making materials, but at this time, can you still bear its value and price?
Wall products are the largest of all bulk building materials products, and also the last link for building materials products to absorb waste residue resources. You have no technology, but you are picky about wasting resources, so you can't achieve circular economy and sustainable development.
Scientific brick-making lies in respecting the original characteristics of these waste residue resources, applying materials according to their characteristics, scientifically mixing ingredients, learning from each other's strengths and overlapping advantages. This is the activated waste residue composite powder introduced below-all waste residue resources are classified, scientifically combined, compounded, mutually activated and stimulated, and mutually adjusted and supplemented.
The final result is to turn the waste residue into a low-grade gelled powder material.
On the basis of this work, you can produce countless kinds of wall and building materials and products by extrusion with a press. Are there any problems with their quality and durability?
Therefore, the production of baking-free bricks and wall materials is the last line of defense to purify the earth's green and ecological environment, and it is the guarantee to digest all man-made and natural sludge and turbid water, turn it into valuable resources, and realize "inch slag and inch gold".
Fifth, the state should vigorously promote the use of activated waste residue composite powder to produce baking-free bricks and block products.
Why: the baking-free brick industry is the base to realize the last link of the ecological chain of "inch slag inch gold"?
1. It is the unshirkable responsibility to completely consume all kinds of waste residue resources to activate waste residue composite powder.
Whether you use it in cement, concrete and cement products, or in construction waste, the activated waste composite powder will be completely consumed unconditionally, and the waste will become a new wall material.
What does this depend on? It depends on science, technology and invention, which is a real circular economy.
Second, the activated waste residue composite powder does not advocate the so-called "high content" of a certain waste residue.
Any kind of waste residue resources can only be compounded with different kinds of waste residues according to how to meet the needs of chemical and physical balance of mineral synthesis of "artificial cement stone".
Activated waste residue composite powder does not depend entirely on the gelation of cement and additives to form blocks and baking-free bricks, but depends entirely on whether each particle powder that constitutes brick blocks can participate in its chemical and physical interaction. That is to say, after a variety of waste residue resources are matched and compounded, it becomes a complex of low-grade cement and admixture. On the basis of this high-quality composite material, a new wall product is made by a molding machine with a certain pressure. At the same time, thoroughly clean up and eliminate all kinds of waste residue pollution sources from the national and global significance.
Sixth, in the baking-free brick industry, activated waste residue composite powder has better special service function than the current chemical admixture.
Its advantages are as follows:
First of all, activated waste residue composite powder can improve the durability of cement and concrete products from the perspective of "strengthening the body from the root".
Secondly, before grinding the activated waste residue composite powder, the fineness of most powder minerals is 100 ~ 200 mesh, which is more energy-saving, electricity-saving and original ecology than other waste residue resources in production, and is conducive to building the baking-free brick block factory into a green industrial base.
Thirdly, the cement produced by mixing activated waste residue composite powder is most suitable for preparing high-strength, ultra-high-strength and high-durability concrete products, which is a major national invention patent technology that has entered a mature stage.
Therefore, technically, it is more capable to ensure that the series products of baking-free bricks and blocks, like cement and concrete products, achieve the purposes of energy saving, resource saving, electricity saving and low cost.
First, because the waste residue resources available for baking-free bricks are more extensive;
Second, the breadth of local materials has been expanded, and the cost of materials can be minimized;
Thirdly, due to the wide sources of materials, the possibility of compounding a variety of materials into low-grade cement powder increases, which will improve the quality and later strength of baking-free bricks and bring broader prospects.
Fourthly, the cement and concrete produced by mixing activated waste residue composite powder has now entered a new stage in the history of cement development-because the rich combination and adjustment minerals in activated waste residue composite powder can effectively give existing products more special functions to meet the requirements of engineering construction, and these characteristics are also applicable to baking-free bricks.
Fifthly, all the waste minerals in the activated waste residue composite powder are made from local materials (the square garden is only a hundred miles away), which saves freight, eliminates pollution, has simple operation, low price and no negative influence, and can be widely used in any area. In other words, it can be used for any kind of building material products.
Sixth, activated waste residue composite powder is a green and bright way to save energy, electricity and resources. It mainly relies on the activation of waste residue and waste liquid to replace chemical additives, or partially replaces or partially combines a small amount of additives, making a groundbreaking and basic constructive contribution.
Seven, how to control the most important "four links" in the production of baking-free bricks and blocks?
First, pretreatment and scientific activation.
According to the source price, reserves and transportation of different local waste residue and liquid resources, different treatment methods are determined. Increase the activation of brick-making raw materials from many angles. So that chemical additives are not used or used less, and the cost of production materials is reduced.
2. Mixing, stirring, rolling, aging, orderly numbering, stacking first and using first.
(1) mixing and stirring is the foundation, which is related to the homogeneity of materials.
(2) rolling, especially high-temperature light waste materials, such as * * *, fly ash, * * *, etc. Due to the high compression ratio, rolling technology must be adopted to adjust the compression ratio after mixing.
(3) Aging is improvement, which is the pre-combination and improvement stage of chemical reaction based on the first step. Until it gets hot.
(4) Orderly numbering, stacking before use, stacking aging time, depending on whether the intermediate temperature of materials rises. Orderly production and stable quality.
Third, control the water-material ratio.
When there is less water, the mineral reaction is not sufficient, but when there is more water, it is not easy to form. After the water vapor evaporates, many gaps are left. Control the water-material ratio, and the water-material ratio should be neither large nor small.
Fourth, nature protection.
Do not burn or steam, the key is maintenance. Timely watering and curing is a special requirement of concrete bricks, especially in the first three days and seven days after molding, which requires special care.
Eight, raw materials of baking-free brick
Examples of variety selection of waste residue resources-Taking Dalian Dahua Group Company as an example;
Request for instructions on cooperative technology development and utilization of alkali residue-taking a project as an example;
The following is the proposal report to Dalian Dahua Group Company at that time:
Dalian Dahua Group Company:
At present, scientific and technological innovation, turning waste into treasure and creating a conservation-oriented society have become the trend of national scientific and technological innovation. Following the trend of the times, our company introduced two national patented technologies in March this year, focusing on the development and research of the technical "problem" of comprehensive utilization of solid industrial waste residue in Dalian.
In the past five months, based on the previous development and production experience of various provinces and regions in China, we conducted a brand-new study on the application of this technology in the alkali residue of Dahua Group.
The results show that Dalian alkali residue is one of the most valuable and important resources among all solid waste residues.
1, alkali residue can be widely used to produce a series of building materials such as cement, concrete and baking-free bricks after scientific treatment by this technical method.
After scientific activation, the activity of alkali residue is greatly improved, and it can become the cheapest material to replace chemical additives in a series of building materials such as cement, concrete and baking-free bricks.
2. Alkali residue can also be developed into new lightweight wall insulation materials and products.
3. Alkaline residue can also be combined with other waste residue resources to become the main mineral resources in cement production, replacing and saving limestone, an ancient fossil resource.
4. Alkali residue is also a valuable carrier and intermediate mineral for treating and eliminating waste acid water from industrial and mine waste liquid pollution sources.
According to the preliminary investigation, Dalian Dahua Group's alkali residue reserves are about 2-3 million tons (conservatively estimated). At present, the Mianhua Island slag dam is close to full, and it is urgent to carry out large-scale scientific management, empty the slag dam and eliminate pollution.
Therefore, we hereby report that:
I urge the leaders of the group company to attach importance to the cooperation of this technology. For the development of Dalian's environmental protection industry and the early construction of Dalian into a new strong city with higher standards and zero pollution and energy saving, I hope to make joint efforts and make more contributions.
To this end, the following requirements are put forward:
First, give strong policy support. Because this is a major environmental protection undertaking.
Second, give preferential treatment economically, because the initial investment in the technical application of alkali residue is large, the development cycle is long, and the capital consumption of equipment and facilities is large.
Third, give strong support to transportation, because after the market is developed, the annual consumption is hundreds of thousands or even millions of tons.
Fourth, in the specific cooperation work, please send several powerful and sophisticated forces to coordinate and solve some details and specific problems that may arise in actual operation.
Please correct me if the above views are correct.
Inventor of patent technology-Wu Fahui