SPONTANEOUS VAPOR EXPLOSION OF MOLTEN MATERIALS IN SALT SOLUTIONS

摘要

In order to clarify the basic characteristics of thespontaneous vapor explosion, experiments were carried out bydropping 20 g of molten zinc at 873 K or same mass of moltencopper at 1473 K into aqueous solution of salts (CaCl2, NaCl),of which quench temperatures are higher than that in purewater under same subcooling conditions in order of CaCl2 andNaCl solutions at fixed concentrations.We observed spontaneous vapor explosion between saltsolutions and molten zinc, which dose not usually occur inpure water, in the quenching regime in salt solutions. Thevapor explosion in CaCl2 solutions easily occurs even in smalldegree of subcooling (close to the saturation point) withincreasing salt concentrations. Molten copper is spontaneouslytriggered in CaCl2 solutions larger than 35 salt weight percentswith a sufficient degree of subcooling ( > 90 K). Ourexperimental results confirmed that molten metals, whichcould not interact with water, cause spontaneous vaporexplosion when using adequate salt solutions.Furthermore, results in the present study indicated that inmany cases the vapor explosion occurs after formation of crust(solidification interface including the mushy zone), which isregarded as a kind of large-scale structure produced byhydraulic deformation called the organized motion. As a result,a mode of spontaneous vapor explosion that crust formationinduces entrainment of coolant and the entrained coolant triggers vapor explosion was discovered in the range of mass(20-50 g) dealt with in our experiment.