Experimental Study On The Properties Of Fly Compound CMC Gel For Fire Prevention

Coal always occupies the basic unshakable position in Chinese energy field.With the improvement of the mechanization level, the safety problems have been gradually upgraded in the mining process, which, especially mine fire is particularly prominent in the coal mines. In order to improve the control effect of internal fire in coal mines, a new gel composite CMC with fly-ash was developed which use metal ion as the key cross linking factor. The gel were composited fly ash and CMC polymer solution what combines inhibiting oxidation of coal also has good mobility, plugging resistance, stability, cement crushed coal and other advantages.The A2B2 and A3B2 composite gels have optimize selected via the orthogonal tests of Composite Fly Ash and CMC water solution and the orthogonal test about composite binders and crosslinking agent which according to gelling time and viscosity of the gel. The gelation rate of the composite gel can be controlled by the slow release agent what can control the gelling time of the composite gel.Anton-Paar MCR-302 rheometer has been used to test the rheological properties of the composite gel, which has found the gel has the shear thinning characteristics; with the increase of shear rate the viscosity becomes smaller,while shear stress increased gradually. When the shear rate of the composite gel suddenly increases, the viscosity of the composite is suddenly reduced. When the shear rate suddenly drops to 0.1s-1, the composite gel needs 10 s to recover to a stable state, and the viscosity is reduced by 30% compared with the initial state. So, the viscosity decrease is help for the diffusion of gel slurry in the fire areas when the gel slurry outflow orifice.Composite gel can be used to fill the broken coal seam in 5min, and the filling rate can reach 89.3%. The composite gel has significant performance on plugging air leakage. The results show that the material can be reducing the air leakage rate to 350%; inhibition experiment showed that composite gel can effectively prevent coal and oxygen binding and significantly reduce the airtight storage environment in CO production which better than silicate gel.With independent design and manufacture of experiment oven to simulate the combustion experiment found that the high-temperature fire area are easy to develop in the direction of the return when the air leakage volume is large; and a secondary high temperature zone of potential fire zone will be produced in the air return direction. When the air leakage quantity is small, the secondary high temperature region will be produced in someplace where close to the air leakage side.It has been found that the glue injection position has a significant effect on the fire extinguishing effect. The extinguishing effect of inject the gel in the area around the fire firstly before inject to the fire area directly is better than injectgel directly to the high-temperature fire area center. The gel first cover and cooling the potential high temperature zone, eliminates the risk of the potential combustion. The experimental results show that the whole experiment furnace internal temperature control degree is good, high temperature region can be compared with the direct fire early 2h dropped in temperature, and the low temperature to 39 degrees, more directly to the center of the fire and injecting fire low 28 degrees.The extinguish mechanism of the new gel have been analyzed from the micro and macro level: composite gel can reduce the rate of coal adsorption to oxygen, reduce the chemical reaction, degenerate and reduce coal inside the active functional groups and free radicals; composite gel can reduce the release of coal and oxygen reaction heat, on the other hand can accelerate coal oxygen contact surface in the vicinity of the heat, so that the uptrend of coal temperature slow, so as to effectively prevent coal spontaneous combustion.This paper through experimental analysis and theoretical research what study and expound the rheology, plugging, gum stability, fire prevention and extinguishing mechanism of the composite gel. The new gel material combined the inhibiting effect of fly ash and polymer hydrogel which can basically meet the needs of coal mine fire prevention and extinguishment. Put forward an effective method what inject the gel in the area around the fire firstly before inject to the fire area directly that lays a theoretical basis for the promotion and application of the composite gel field in the future.