Oxygen Distribution and Air Leakage Law in Gob of Working Face of U+L Ventilation System

Abstract

In order to prevent and control coal spontaneous combustion effectively in the gob of U+L working face, the 30105 working face of Hanglaiwan mine was taken as the research object. The relationship models between oxygen concentration and burial depth of the two tunnels in the gob of U+L working face were established. The distribution of oxygen in the gob of the working face of U+L ventilation system was studied by field observation combined with numerical simulation. The results show that the air leakage in the gob is serious. There are a number of fluctuation areas where the oxygen concentration first decreases and then increases in the air intake side of the gob. The oxygen concentration peaked at 100m, 175m, and 245m, respectively, from the intake side of the gob. In the same position of the gob depth, the air leakage intensity on the intake side is generally higher than that on the return side, and the oxygen concentration on the intake side of the gob is slower than the return side. Oxygen concentration maintains at 5.09% when the depth of gob reaches 400m. Measures to prevent coal spontaneous combustion should be strengthened in the air intake side.

Study of the influence of the characteristics of loose residual coal on the spontaneous combustion of coal gob

“…The grouting covers the surface of the coal and seals the voids in the loose coal, reducing or even preventing air leakage, and isolating the contact between the coal and oxygen. In addition, the grouting absorbs the heat stored in the spaces around the coal, reduces the temperature of the coal, destroys the various active groups on the surface of the coal (Figure ), and prevents oxidation of the coal …”

“…In addition, the grouting absorbs the heat stored in the spaces around the coal, reduces the temperature of the coal, destroys the various active groups on the surface of the coal (Figure 9), and prevents oxidation of the coal. [42][43][44] We suggest the adoption of the step-by-step nitrogen injection method for fire prevention and extinguishing in working face #10414. The recommended nitrogen injection step is 30 m. When a large amount of high concentration nitrogen is injected into the gob (Figure 9), the oxygen concentration and the air leakage into the gob can be reduced.…”

Distribution Law of Three Spontaneous Combustion Zones in the Goaf Area of a Fully Mechanized Working Face under High Ground Temperature

“…Coal oxidation and spontaneous combustion must meet three conditions at the same time: (1) The coal has a tendency of self-ignition and is accumulated in a broken state; (2) Continuous ventilation and oxygen supply conditions; (3) Continuous heat accumulation environment, and sufficient time for oxidation. In mine goaf area with coal spontaneous combustion tendency, the volume of air leakage directly affects the oxygen supply and heat accumulation conditions of the coal, and the O2 concentration directly determines the oxidizability of the coal seam [19][20][21]. Therefore, the division of the three spontaneous combustion zones in the goaf area is based on three criteria: air leakage speed, temperature distribution, and O2 concentration [22,23].…”

Recapitulation and Prospect of Research on Flow Field in Coal Mine Gob

“…e closed gas in the extraction area experiences a critical period when the gas concentration fluctuates between the upper explosive limit and the lower explosive limit [101,102]. Since gas influx from the extraction zone cannot be detected, some scholars have analyzed gas transport patterns by scaling down experimental devices or numerical simulations [103][104][105][106][107]. ese methods mainly focus on the changes of oxygen or methane concentration distribution in the extraction zone.…”