Experimental Study On New Foamed Gel Material For Preventing Spontaneous Combustion Of Coal

Spontaneous combustion of coal is one of the major disasters in the process of coal mining.In the prevention and control technology of coal spontaneous combustion,gel foam is considered as a better new fire control technology because it takes into account the advantages of gel and foam fire extinguishing technology.The existing mine organic or inorganic foamed gel's disadvantages contains low foaming multiple,lack of temperature resistance and salt tolerance and poor stability,so this paper carried out the research of gel foam for preventing spontaneous combustion of coal.The foaming agent,foam stabilizing agent and compound coagulant and three hand needle was carried out on the foaming properties,temperature and salt resistance performance,stability and resistance and finally formed a foamed gel material for preventing spontaneous combustion of coal which has a high foaming multiple and good stability.The main achievements are as follows:In this paper,the foaming agent,foam stabilizer and gelling system of gel foam were investigated systematically.The bubble level of single bubble agent was tested by the method of attack and the orthogonal experiment was carried out after optimization.Finally,a comprehensive scheme with good performance and small dosage was obtained.On the basis of this,the temperature resistance performance and salt tolerance of the composite foaming agent,coal mine fire extinguishing foam and AOS were tested and the result shows that the compound foaming agent has obvious advantage in both two aspects.At last,the best foam stabilizer was obtained and the concentration of it is 2.1%.According to the principle of the plastic forming of the material and its effect on the foam,several gelling systems were investigated and one kind of gelling system(J and G)with good performance and controllable time(20min)was determined.The effect of concentration and temperature on gelation time was studied.The research shows that gelation time is shorter when the total concentration of two kinds of material J and G glue system was higher;the gelling become faster when liquid temperature is higher at the same concentration.The stability was also investigated.Under normal temperature,there is still no water appearing after 8h of observation;the impact of the colloid foam is less and the average foam significantly reduced when the temperature increases.In contrast,the advantages of colloidal foam is obvious.Finally,the laboratory study concludes that the total amount of compound foam in the base liquid is 4‰ and the amount of J and G in the gel system is respectively up to 3‰ while the amount of foam stabilizer is 2.1% when pH was in 7-9,the best performance was achieved.Its foam ability is 1.2-1.4 times of those of others and its half time of foam is 98h? In addition,the viscosity of the foam was investigated from two aspects of the foaming ratio and temperature.The results show that the viscosity firstly increases with the increase of foaming times and then decreases;and there is a negative correlation between temperature and viscosity.Finally,the flame retardancy of gel foam was investigated.The result shows that the foam has a good flame retardancy and significantly slows down the oxidation process and reduces the heat release rate and the release of CO.According to the experiment,the temperature of the foam gel immersion sample is delayed by about 20? to get the same amount of CO release when the temperature is more than 100?.Calculations shows that the gel foam Eco equals 66.33% at 100?.