Research On Spontaneous Combustion Control Techniques Of Fully Mechanized Caving At Large Inclined Angle And Inflammable Seam

The number of spontaneous fire accounts for more than 90% of the total counts, and 80% of one occurs in thick seam. Coal reserve of large inclined angle is about 14.05% of the total ones, so spontaneous combustion prevention of large inclined angle and thick seam is a tougher problem. The coal seam of Gushan mine is very inflammable,065-2 fully mechanized caving working face is one of inflammable, thick and large inclined angle seam. Under the worst influence of old fire area, the coal has strong spontaneous combustion tendency and short combustion period, the possibility of recrudescence and spontaneous combustion of caving seam due to the holing through working face and near old fire district in small coal mine are larger, their occurrence and development speed are fast, prevention of spontaneous combustion is difficult. For different caving stage, based on site actual situation, the methods of combining field test, indoor experiment, theoretical analysis, numerical simulation with engineering application are used, the major work and the results achieved are as follows:(1) Through reservoir of sampling, thermo gravimetric indoor and spectral characteristics experiment, spontaneous combustion characteristics of coal and production law of index gases in Gushan mine are studied, inhibiting effect experiment with different ratios resistance foam and coal samples is carried out,1:2 ratio that is favorable to increase ignition temperature and activation energy of coal samples is proposed.(2) Through gas and temperature monitoring of goaf in 065-2 working face and numerical simulation, the distribution of oxygen concentration, temperature, air velocity and oxidation zone of goaf in large inclined angle, nearly horizontal and gently inclined fully mechanized caving face are different, the characteristics of goaf in fully mechanized caving face with large inclined angle are got.(3) Using COMOL Multiphysics 4.3b2D software, through numerical simulation, the sensitive response indexes of air volume in working face including the depth into goaf of the end boundary of oxidation zone and maximum air velocity are achieved, the results that nitrogen injection time and the width of oxidation zone have a approximate "Z"-shape Boltzmann relationship, and there are problems of significant and maximum effective time while continuous nitrogen injection are proposed.(4) Using the numerical calculation means to systematically study the effect on building separating wall in working face to regulate air structure of goaf from length, spacing and channels.the quantitative relationship between different technical parameters of air regulation and the width of oxidation zone in goaf is got, effective protection scope of building isolation wall is also got; the method of determining isolation wall parameters by combining effective protection distance, approximate" V "relationship, engineering quantities and actual conditions is pointed out.(5) Through numerical simulation, the quantitative change law of air vector and the dangerous area of spontaneous combustion using top coal caving technology by stages is indicated, the result that it can change air direction, reduce air speed and dangerous area range is proposed, and it has important function and meaning to cross safely the old fire area of large inclined angle and inflammable working face under the influence of fire.(6) Integrated controlling technology of spontaneous combustion such as strengthening goaf and old fire area monitor, plugging air leakage, reasonably controlling or reducing air flow, injecting nitrogen within the valid time, shortening nitrogen injeetion step, building proper length and dense firewall in the effective protection distance, strengthening advanced detection of old fire area and comprehensive prevention before and during mining, reinforcing roofs and mine roadway to ensure airtightness of gel and foam inhibitor, shortening pipe alternate distance, using porous material to inject a lot of inhibitor foam, top coal caving by stages etc are pointed out, high efficiency and safety production of inflammable and large inclined angle seam in fully mechanized caving working face under the influence of fire area is successfully realized.