Preparation Of Al-XG Composite Gel And Experimental Study On Inhibiting Coal Spontaneous Combustion

Spontaneous combustion of coal will cause waste of coal resources,casualties,pollute the atmospheric environment,and induce secondary disasters and other adverse effects.In order to prevent spontaneous combustion of coal,scholars at home and abroad have proposed a variety of fire-fighting technologies,such as grouting,spraying of chemical inhibitors,foam injection,gel injection,inert gas injection,etc.,but these technologies still have certain deficiencies.Based on this,in this paper,an environmentally friendly,non-toxic,high-efficiency and durable Al-XG composite gel was prepared using xanthan gum（XG）as the base material,Al³⁺as the cross-linking agent,and flame retardants to prevent coal spontaneous combustion.Through the basic performance test of the gel and the experiment of the exothermic characteristics of coal,the most suitable ratio of the composite gel for fire fighting was screened out.The composite gel has the effect of inhibiting spontaneous combustion of coal and revealed its mechanism of inhibiting spontaneous combustion of coal.The main conclusions are as follows:（1）Performance characterization of Al-XG composite gel The test results show that the gel has a regular lamellar structure inside;the gel properties of different ratios are very different,and the thermal stability of the Al-XG-3 composite gel The permeability and swelling rate of the prepared Al-XG composite gel gradually decreased with the increase of xanthan gum concentration.Combined with the needs of engineering applications,the Al-XG-3 composite gel was screened out.Suitable for fire fighting.（2）By testing the exothermic properties of coal treated with different ratios of Al-XG composite gel,it is found that Al-XG composite gel can absorb a lot of heat,delay the initial exothermic temperature of coal,and effectively reduce the exothermic intensity of coal.The results of thermodynamic analysis show that the Al-XG composite gel can increase the apparent activation energy of the coal-oxygen composite reaction;the Al-XG-3 composite gel has the best effect on inhibiting the heat release of coal.（3）Through the temperature-programmed oxidation experiment of coal,the variation law of coal spontaneous combustion index gas during the oxidation process of each experimental coal sample was obtained.The results show that compared with Mg Cl₂inhibitor and water glass gel,Al-XG composite gel can reduce the oxygen consumption rate of coal and the generation of CO and CO₂to a greater extent,delay the occurrence of C₂H₄temperature in coal oxidation,and reduce the temperature of coal oxidation.The amount of CH₄and C₂H₄released.（4）It can be seen from the scanning electron microscope test that the Al-XG composite gel can completely coat the coal body without cracking after dehydration,which plays a good role in oxygen barrier and sealing.Infrared spectrum test results show that the Al-XG composite gel can reduce the content of oxygen-containing functional groups,aromatic hydrocarbons and aliphatic hydrocarbons in coal,inhibit the activity of functional groups,and reduce the spontaneous combustion tendency of coal,thereby achieving a lasting effect of inhibiting coal spontaneous combustion.In addition,this paper revealed the mechanism of inhibiting coal spontaneous combustion from the three aspects of the Al-XG composite gel’s effect of oxygen isolation and displacing,endothermic heat dissipation,functional group reduction and chain reaction interruption.This paper has 41 pictures,12 tables,and 109 references.