Mine blasts

754,155. Means for preventing fire-damp ignition and tampings for boreholes. DEMELENNE, A. April 6, 1954 [April 10, 1953; June 5, 1953; Nov. 20, 1953], No. 10038/54. Class 9(1) Liquid charges are provided to reduce the danger of fire-damp explosions and to decrease the dust from the blasting operations, these charges may be injected into the rock face or used as tampings. The containers for the charges are of synthetic resins or synthetic plastic materials. The liquid filling may be water to which substances inhibiting burning may be added, e.g., calcium chloride or sodium chloride. Any suitable means may be used to seal the container, such as adhesive, or welding. Means to indicate whether the container is intact may be provided together with means for indicating its presence in a borehole. To do this fluorescent, or phosphorescent paint may be applied to the container, or the container may be trans-. parent or translucent and a phosphorescent or fluorescent substance be incorporated in the liquid. The liquid may be enclosed in an inner frangible container within an outer protective casing, which may be of metal, cardboard or synthetic plastic material. The container may be placed in boreholes after or before the insertion of the explosive cartridges, the entrance to the bore being closed by a tamp- . ing. A small amount of a wetting agent may be added to the liquid to reduce surface tension Other substances which may be added to the liquid are ferrous oxide, calcium carborate and sodium carbonate: Oxidizing agents such as potassium permanganate and hydrogen peroxide may be added. Specification 747,699 and Belgium Specification 515,939 are referred to.