Performance Evaluation And Processing Method Study Of Activated Coal Gangue Used In Architectural Engineering

This paper explores the application methods of two main types of guangue, which discharged fromdifferent coal mines in Shaanxi province, in architectural engineering, In the research, experimental studieswere conducted. The main results are reported as follows:1.The main mineral composition of quartzite gangue is quartz and has low potential pozzolanicactivity.The gangue can be broken into appropriate particle size to replace the natural sand. The freshmortar and mechanical properties in different dosage of the gangue artificial sand are studied. Researchesrevealed that: the coal gangue powder （particle size less than0.075mm） produced from the fragmentationprocess can be added into the mortar as insert filler. The workability of the fresh mortar can be improvedby mixing with coal gangue powder at20%, while the cube compressive strength and axial compressivestrength of the mortar are also increased. The coursing degree of mortar is minimum when50%of thegangue of artificial sand is substituted by river sand. The axial compressive strength and modulus ofelasticity of the mortar reach minimum of70%of the gangue in artificial sand substituted by river sand.2.The main mineral composition of clay rocks.is kaolin. The optimal calcining temperature of coalgangue for heat activation of this coal gangue and activity level of thermal activated coal gangue indifferent calcined systems were investigated by X-ray diffraction （XRD），thermogravimetric-differentialthermal analysis（TG-DSC）,scanning electronic microscopy （SEM） and other testing means, combiningwith the means of Ca（OH）₂consumption, Intensity ratio method,means of ions consumption in Aqueousalkali, extent of reaction method and other activity evaluation method.At the meantime, the respectivecharacteristics of the several activity evaluation method is compared.The test results shown that the gangueis beneficial for forming high pozzolanic activity when the calcination temperature at650℃, the size range of0.15⁰.30mm and the calcination time at1.5h³.0h. The means of the Na+ions consumption in NaOHsolution can determine the calcined gangue activity quickly.3.Calcined coal gangue in fluidization is simulated by fluidization numerical simulation program. Thedynamic characteristics of gangue particles in the fluidized bed at both room and high temperature states isstudied by analyzing the curve of the whole bed pressure and the apparent wind speed, the critical flow ofwing speed, the pulsating variance of the whole bed pressure drop, minimum mixing time and a number ofindicator. The results shown:①The pressure drop in fluidized bed enlarges with improvement of the apparent wind speed. Theinflection point appears when the flow of wind speed reaches the threshold limit value. The fluidized bed isthen entered to the full flow stage, the pressure drop inside the bed shows intense pulsating;②Critical fluidization velocity of large particle will increases along with the increment of temperature.At the same temperature, the minimum mixing time of particle will cut down with increasing of thefluidization number. At the same particle size, the minimum mixing time at high temperature state isgreater than room temperature. For small gangue particles, the critical fluidization velocity drops whiletemperature increases. At both high temperature and room temperature state, the minimum mixing time hasno significant change with the increasing of fluidization number;③The average pressure drop for the gangue of same particle size has little change against the changesin temperature and fluidization number. Room temperature test can be used to predict the whole bedpressure drop for fluidized bed reliably. The whole bed pressure drop reduces continuously with decreaseof particle size. At the same fluidization number, the pulsating variance of the fluidized bed pressure dropin high temperature state is lower than room temperature state. The fluidized bed runs more stability at high temperature state.