|
A mathematical model of inflow of toxic gases during disintegration of chemical sealants applied in |
|
|
|
|
A mathematical model of inflow of toxic gases during disintegration of chemical sealants applied in undeground mines Authors: W. Dziurzyński, A. Krach
Fires in collieries pose a major threat and may lead to serious accidents. Organic sealants, such as polyurethanes and urine-formaldehyde resins, have to be widely used in mines to stabilise the rock strata, to seal galleries and fill the voids. Sometimes these sealing agents have to be applied in the conditions of already spreading fire. It is reasonable to suppose that the flowing air is heated up by the fire source and in contact with chemical agents it will lead to the process of chemical decomposition. A technique to precisely evaluate how the presence of final products of (thermal ?) chemical decompositions of sealants might still enhance the risks of mining operations is still lacking. The danger is there, as the flowing air will now contain toxic gases, such as hydrogen cyanide. A method is proposed whereby the potential risk due to the inflow of toxic gases should be assessed on the basis of prognosticating techniques utilising computer simulations of the ventilation processes, supported by specialised software. These techniques enable us to monitor the variations of gas composition distribution in response to the preset input. Distributions of gas composition are computed using mathematical models of air outflow and the sources of inflow in the ventilation network. The paper provides the background information and main assumptions underlying the mathematical model of inflow of hydrogen cyanide, which is a final product of high-temperature oxidation of urine-formaldehyde foam. Model parameters are determined on the basis of specialised tests performed in the Laboratory of Physico-Chemical Properties of Non-metallic Materials in the Department of Materials Engineering of the Central Mining Institute. The paper gives the model parameters obtained for one substance: hydrogen cyanide (HCN).
|
2011