Method for prewarning spontaneous ignition of coal mining face in hierarchical composite index system

The invention provides a method for prewarning spontaneous ignition of a coal mining face in a hierarchical composite index system. CO critical reference values at a goaf oxidation zone, a return aircorner and a return air flow are acquired from test data, and CO contents at the goaf oxidation zone, the air return corner and the return air flow are also obtained through actual measurement as theCO critical reference values, so that equivalently, through combination of on-site actual measurement results and the test measurement results, the CO critical values for spontaneous ignition at the goaf oxidation zone and at the return air corner are determined; thereafter, prewarning levels are further obtained in combination with the presence condition of C2H4 and C2H2 gas in a goaf. Accordingto the scheme provided by the invention, the CO critical values can be obtained through comprehensive consideration of the on-site measurement results and the test results, and prewarning levels are reasonably divided and forecasted in combination with different gases, so that a theoretical and application basis is accurately provided for prewarning of the spontaneous ignition of the coal mining face; the method is effective and reliable.