Raw Materials for Fabrication of New Type, Environmentally Safe Fire-Extinguishing Powders and Evaluation of their Efficiency

摘要

Selection of local mineral raw materials for production of new type, environmentally safe, highly effective fire-extinguishing powders are discussed in the paper. As is known, the commonly produced fire-extinguishing powders mostly are halogen containing and cannot satisfy the modern demands, in the first place from the viewpoint of effective, non-toxic and environmentally safe using. Therefore, development of halogen free, non-toxic, environmentally safe fire-extinguishing powders is currently a very important problem. Local mineral raw materials - zeolite, clay shale, perlite, dolomite, barite-calcite and ammophos are taken as the basis for receiving such powders. Raw materials were selected according to their high performance properties and due to the factors indicating the reduction of combustion processes, which can be predicted using the results of chemical and thermal gravimetric analysis. Such raw materials mainly contain alkali and alkaline-earth metal carbonates, bicarbo-nates, oxalates, silicates, Fe, Al and alkali metal hydroxides, crystallization water. At their Intensive heating incombustible gases, water steam and metal oxides are separated. Incombustible gases and water steam in flame zone are functioning as phlegmatizer and in surface zone are causing the formation of swelled layer. Protective films of metal oxides, swelled and coked layer cause a strong "fire-limiting" effect. This indicates the fact that they are characterized by high inhibition properties. It is stated, that zeolites in composite powders can act as efficient hydrophobizing agents. It allows to create a wide range of zeolite-containing fire-extinguishing powders on the basis of local mineral raw materials.