Experimental Study On The Pozzolanic Performance Activation Of Coal Gangue With High CaO From Xinyang Mine

The main mineral composition of coal gangue are Kaolinite and other clay minerals which are of potential pozzolonicity.So it can be activated and used as cement material,which contribute to alleviate the side effect caused by disorderly stacking of coal gangue,such as the occupation of land and environment pollution,and decrease the cost of cement back filling material in back fill coal mining.At present,the research on the pozzolanic activity of coal gangue mainly concentrates on thelow-calcium oxide gangue containing about 3% of calcium oxide and during the activation process,the separation of Si and Al in gangue can not be fully separated,which results in a insufficient pozzolanic activity of coal gangue.In this paper,pozzolanic activity of high calcium oxide gangue from Xinyang coalmine was studied by laboratory experiment and theoretical deduction method combined with XRD,XRF,ion concentration detection?ICP-AES?and othermodern test technology.Firstly,analysis of XRD and XRF shows that the coal gangue taken from Xinyang mine is of latent pozzolanic activity as it containing a higher kaolinite,SiO₂,Al₂O₃,and CaO.Secondly,by studying the influence of coal gangue parameters,water cement ratio,the age changes on the hydration degree of high Ca O coal gangue activated by mechanical and cement in slurry,it is found that: ? With the increase of age and water binder ratio,the degree of coal gangue and cement increased,and the hydration rate of coal gangue reached a good point at the parameters of 30%,but cement at the parameters of 40% when slurry have a centain parameter of gangue;With the increase of coal gangue parameters and decrease of water cement ratio,the hydration degree of coal gangue decreased,with increasing of coal gangue parameters and water cement ratio,the hydration degree of cement increased when slurry have a certain age;?Based on the modification of the formula of pure cement hydration,the prediction model of cement hydration degree in mechanically activated high calcium oxide coal gangue cement paste was deduced.Again,thermal decomposition rule,electrochemical rule of high calcium oxide coal gangue activated by mechanical thermal and the performance of the paste is studied,it is shown that: ? With the increase of activation temperature,coal gangue structure change has experienced four stages: coal gangue adsorption water and structure water evaporation stage,stable stage,weight loss for organic carbon and volatile phase and coal gangue mineral decomposition stage,and the decomposition rate of coal gangue reached a maximum value at 700?,? The dissolved of high CaO coal gangue in distilled water is firstly the CaO in coal gangue react with water to produce Ca?OH?₂,forming a strong polar dissolved alkali environment,accelerating the activity of dissolution rate of active ions in coal gangue,following by the reaction of Si⁴⁺,Al³⁺ and Ca²⁺,OH-,forming insoluble material;? with the activation temperature increase,viscosity,compressive strength of cement paste increased firstly then decreased,reaching the maximum value at 700?,but the contrary rule of the paste setting time,and 700? reaches the minimum value,it is deduced that the optimum activation temperature of mechanical thermal activated coal gangue is 700?.Finally,electrochemical properties of coal gangue,with high calcium oxid,activated by the mechanical-thermal-chemical and the related properties of paste compouned by activated high calcium oxide coal gangue and cement was studied then the Fermi surface of kaolinite is calculated,it is found that: ? with the increase of activation temperature,compressive strength of paste increased,but a opposite changes,with increase of mass ratio of Na₂CO₃ with high Cao coal gangue,and with the activation temperature and the proportion of sodium increases,viscosity of paste compouned calcium oxide coal gangue and cement shows a trend of increase,but the initial setting and final setting time decreases;? The conductivity of activated coal gangue in distilled water is determined by the ratio of sodium carbonate and activation temperature,but PH is controlled mainly by the temperature factors;...