Gangue Activation And Applied Research In Building Materials

Coal gangue is an industial solid residues raised from the floatation process. It accounts for about 10%-20% of carbon production in our country, and it is one of the largest industrial waste residue emissions.The stacked coal gangue not only occupes a lot of land, but also pollutes the surrounding environment. Serious methods such as mechanical activation, heat activation and complex activation were used to inspire the activation of neimenggu coal gangue which has high aluminum contents.Particle size, specific surface area, ensity and cement mortar test, as well as XRD etc have carried on mechanical activation of coal gangue. The result indicates:after 1h of grinding, the particles below 10 u m has been up to 56.08%; Under the same grinding time, the coal gangue jioned sodium hexametaphosphate has more smaller particles, it indicates that sodium hexametaphosphate is favorable to grinding; The particles surface area of coal gangue increases as the grinding time extend; By anaysis of cement mortar test, the coal gangue jioned sodium hexametaphosphate afer 3h grinding has the highest strength when blend with 20%, the 28d compressive strength of cement motar reached 45.38MPa, that is 90% of cement at the same curing age. Analysis of XRD result indicates that the kaolin crystal does not have the settingization gradually as the grinding time extand.The activity of coal gangue calcined at different temperatures was examined by means of cement mortar test, and the result showes that original coal gangue does not produce activity or the activity is very low, but the activity of coal gangue can be obviously improved after high temperature fired. Neimenggu coal gangue has some particularity, and the coal gangue after calcined by the temperature of 800℃has the highest strength in the cement mortar test. SEM observation, X-ray diffraction and infrared spectral analysis show that the kaolinite of coal gangue absolutely decomposed under the temperature of 800℃, and it has been chansformed to amorphous silica and alumina.The activity of coal gangue calcined at 800℃and followed by so called chemical activation was also examined by means of cement mortar test. First, tow calcium increasing way was examined, one way is coal gangue and calcium are calcined together, the other way is calcium was jioned after coal gangue was calcined. The result shows that the first way is better than the second way. Secondly, Na2SiO3·9H2O and Na2SO4 was jioned in coal gangue after calcining together with calcium, and the cement mortar test indicates that the most appropriate condition is simultaneous 15% calcium and 2% Na2SO4.Meanwhile, this paper also referred to application in concrete and grouting material of coal gangue calcined under 800℃. The results indicates that coal gangue is conducice to later strength and Rebar corrosion resistance of concrete. The application in grouting material has a good result, the using of coal as admixtures is better than as cementitious material.