Application Study Of Microwave Radiation Coal Gangue Wall Bricks And Floor Tiles

Coal gangue, a kind of lower calorific value rock, is not pure at all. Instead, it's the mixture of rocks and carbon -containing substances.It is estimated that the total number of heaped coal gangue storage amounts to 250 million tons. Its storage occupies much cultivated land, and worse still, it becomes great pollutants to people and the environment on account of weather and erosion.By the end of 2000, the number of total coal deposit in Yunnan province had reached 2406 million tons, and being placed eighth of the whole country, or second of the 14 Southern provinces, while the number of coal gangue discharge is some 50 million -60 million tons each year, being placed first as solid waste discharge in Yunnan province. Therefore, Yunnan, in its sustainable development, encounters one of its puzzling questions as to how to reuse the coal gangue to make high value-added products by means of high technology.Nowadays, coal gangue is mainly employed to make general building materials, high-grade building ceramic tiles, coating materials and fillings, high value-added products, and stuffing in road building.The ceramic tile has been one of building's decorate materials since a long time. Kaolinminerals is raw material of ceramic tile.According to statistics, output of our country ceramic tile achieves 171.5 million square meters, account for 2/5 of world's output in 2002 year. With developing science technology improving and administer level advancing, quality and variety of our country ceramic tile has very changed. But clay raw material of ceramic tile increase losing of cultivated land, we must look for new raw material of ceramic tile as quickly as possible.This paper analyzes sample of Yunnan Diandong Region coal gangue, and finds the coal gangue contains kaolinminerals. montmorillonite, SiO₂, silicate mineral and so on. It resemble with raw material of ceramic tile, and kaolinminerals is 68.7 percent, therefore, this paper discusses problem that ceramic tile is manufactured by coalgangue substituting to clay raw material.Architecture ceramic adobe are composed by acidity oxide SiO2;middle oxide Al2Oy, alkali metals oxide K2O, Na2O, CaO and MgO and so on, meanwhile, it also contains a little impurity oxide such as Fe, 77, etc. For satisfying using properties of tile, generally, adobe chemical composition are SiO2 45.00 percent-60.00 percent, Al2Os 18.00 percent-35.00 percent, CaO+MgO 0.50 percent-2.00 percent, K20+Na20 3.00 percent-6.00 percent, Fe2Oi+TiO< 1.00 percent and loss on ignition< 15.00 percent. The study indicates that coal gangue chemical composition of Lai Bing and Er San satisfy requisition of manufacturing tile, and they are kaolinminerals-high-aluminum-coal gangue.However, when traditional craft is adopted in making adobe, not only the shaping and sintering of tiles will be affected, but also much more energy will be consumed, and the breaking rate of adobe will be increased, hence the cost is bound to rise. All this is because of the fact that coal gangue, compared with clay, has higher hardness, higher drying lineal shrinkage, higher carbon content, but lower plasticity index.This paper deeply studies technical properties such as granularity, hardness, carbon content, plasticity, sintering, drying, cohesiveness, sliming characteristic of gaolinminerals-high-aluminum-coal gangue. The research indicate that two coal gangue have higher hardness (4.00 and 6.00), higher drying lineal shrinkage (2.30 percent and 2.50 percent) , more moisture content (4.70 percent and 5.90 percent) , but lower plasticity index. They can be manufactured tile by improving raw materials component.This paper establishes total reaction heat empirical formula of kaolinminerals-high-aluminum-coal gangue by reaction behavior of kaolinminerals and impurity in two location coal gangue.where Q'= total reaction heat per block (kJ/block);2100= reaction heat of AI2O3 per kilogram (kJ/kg);Al2O-i= mass of AI2O3 in dry coal gangue adobe material (%);Gp = mass of dry coal gangue by sintering (kg/block);K= content coefficient of coal gangue ash, ^ = 1.05-1.10.At the same time, this paper ascertain influence factor of coal gangue sinter quality, i.e., granularity, rising temperature speed, constant temperature time, burning extent, choice admixture, sintering atmosphere, etc.For reducing blindness of microwave radiation coal gangue tile, the paper sets down production scheme of kaolinminerals-high-aluminum-coal gangue ceramic tile by traditional craft, and confirm each step of production technics.1. Raw material crushing: Chunky raw material is crushing with machine from 40.00mm -50.00mm to 0.30mm-0.50mm;2. Raw material pre-sintering: For satisfying requisition of making tile, raw material must be pre-sintering 5.50 hours.3. Mixing material: pre-sintering coal gangue 21.57 percent, Er san clay 55.15 percent, porcelain clay 23.20 percent;4. Fine crushing mixing material: Granularity of adobe coal gangue tile is controlled from lO.OOum to 61.00(am;5. Slurry dehydration: Adobe slurry in cloth wrap is compressed under extrusion machine, and moisture content reduce down 12.00 percent-13.00 percent.6. Knead and placed: Adobe slurry is kneaded by hand, and placed 12.00 hours in normal atmosphere;7. Adobe molding: Using half-dry-compressing, molding compressive strength is 58.20MPa;8. Adobe drying: natural draying, moisture content is no more than 5.00 percent after drying;9. Sintering: The sintering temperature is 1250°C-1300°C, rising temperature is 2 °C/minute;high heat preservation is 900°C and 2.50 hour, refrigerant temperature speed is about 5°C/minute or so;10. Atmosphere system: The sintering will change tile's sintering temperature, maximum sintering shrinking, over-sintering swell content, lineal shrinkage content and ceramic glaze quality during oxidation atmosphere and deoxidizing atmosphere, etc.The experiment indicate that, according to above method, kaolinminerals-high-aluminum-coal gangue tile possesses high molding, high strength, better abrasion resistance, better rapidly cold and heat resistance;meanwhile, this tile has not a lot of limit to mass of K.2O> NCI2O and FeiO-i.According to above research, this paper takes measure, i.e., microwave radiation technology, microstructure analysis method, chemical analysis method, macrographic examination and establish dynamics model of microwave radiation tile, and study technics and mechanism of kaolinminerals-high-aluminum-coal gangue ceramic tile under microwave radiation, and resolve special problem that it cannot be resolve during traditional pre-crushing, pre-sintering, drying and sintering technology.1. Microwave radiation pre-crushing coal gangue raw materialThe crushing is maximum consuming energy during mineral treatment process. It generally account 50.00 percent-70.00 percent. Owing to compare to clay, raw material of kaolinminerals-high-aluminum-coal gangue possess higher hardness, therefore, traditional crushing technics will bring about consuming more energy and rising cost of tile.The microwave technology can reduce crushing strength of coal gangue, milling expenditure, economy energy, reducing cost.This paper indicates that traditional milling technics need 4.00 hours when coal gangue is milled to 325 without microwave radiation. The milling only needs 55.00 minute after microwave radiation 5.00 minute. So, microwave radiation pre-crushing coal gangue raw material can save 1/2 of electrical fee in actual project per year.2. Microwave radiation pre-sintering coal gangue raw materialThe kaolinminerals is one of essential component. It's plasticity, felting property and suspend property make for molding, meanwhile, sintering temperature is widened and prevent deformation of tile during sintering process. If there are a lot of kaolinminerals and less impurities, adobe of coal gangue ceramic tiles has higher refractoriness, whiter, higher strength, better heat stability, better chemical stabilityA lot of carbon and impurities integrate with kaolinminerals (no more than 68.70 percent) in coal gangue of Lai bing and Er san. They contain carbon, breeze, plantsfossil film;and hydrocarbon of iron, titanium and so on.The microwave can eliminate carbon and impurities of coal gangue in pre-sintering, and gain kaolinite. The experiment expresses that coal gangue eliminate physics adsorption water, part organic material and its crystal structure will not change when frequency of microwave is 2450MHz, power of microwave is LlOkW, reaction time is 2.00 minute. When reaction time reaches 5.00minute, there are doffing hydroxide reaction and give rise to producing unformed kaolinite and carbon cannot thoroughly burn. When reaction time reaches 8.00 minute, highly reaction temperature, coal gangue has completed doffing hydroxide reaction, organic material and possessing white.3. Microwave radiation drying adobe of coal gangue tileMicrowave radiation drying is a better perfect way that it dry thinner and higher moisture content coal gangue tile.The research indicate that coal gangue adobe will uniformly pull off model, less deform, no produce crack by controlling microwave power and in rational doff model time during microwave radiation quickly drying. To compare to tradition drying, efficiency of microwave radiation will higher 33.75-36.00 times than tradition drying. For example, efficiency of pulling off model will be advanced (no more than 10.00 percent), and reduce time of pulling off model from 180.00-270.OOminute to 5.00⁸.00minute, meanwhile, microwave produce will realize industrialization and without pollution. The microwave is better rational producing equipment of coal gangue tile.4. Microwave sintering adobe coal gangue tileThe paper study principle of microwave sintering coal gangue tile and changing composition of kaolinminerals-high-aluminum-coal gangue adobe, one another reaction principle of microwave to adobe of coal gangue tile;and establish dynamics model and strength regression formula of kaolinminerals-high-aluminum-coal gangue ceramic tile.where AL= shrinkage after grain sintered;Lo= space of two ball centre;Dv= coefficient of volume expanding;t= sintering time;y- surface energy per cube;3= particle diameter;ï¿¡=constant;T= absoluteness temperature.>?=x2-14.15jc+75.05 where y= breaking ratio of kaolinminerals-high-aluminum-coal gangue adobe(%);jc= mass of admixture(%);These works confirm fact that characteristices of coal gangue ceramic tile of microwave sintering can be improved by adjusting coefficient of mass, density, power, grain size, variety and quantity of admixture.This paper deals with the systematic research into the mechanism and technology of making tiles with Yunnan kaolinminerals-high-aluminum-coal gangue based on the combined advantage of microwave radiation technique, microstructure analysis, chemical analysis, macro performance test and the establishment of microwave radiation model.The research result suggests a solution to the technique problem that coal gangue has higher hardness, higher drying lineal shrinkage, higher carbon content and lower plasticity index by means of the application of microwave radiation technique to pre-breaking, pre-drying, drying craft and sintering, which offers a new approach and raw material to develop tiles.Few manufacturers have stepped further in making high value-added tiles with coal gangue, and no one in Yunnan has ever filled in the gap of this field, whether in pure theory or in practical application. So the introduction of microwave radiation technique into making coal gangue tile is a first, even in the whole country.