Commonwealth Scientific and Industrial Research Organisation

Robert Gordon Winks

Colin Joseph Waterford

Aleck James Hunter

A formulation for use in the controlled generation of phosphine comprises a mixture of a particulate phosphide and a water-immiscible compound. The water-immiscible compound is paraffin oil, petroleum jelly, a mixture of these materials or a wax having a melting point in the range 35&deg; C. to 65&deg; C. The phosphide comprises from 65 to 85 per cent (by weight) of the formulation. Such a formulation can be added progressively to water in a reaction chamber. Alternatively, the formulation can be packaged in a water-impermeable container from which a region can be removed to expose the formulation to water vapor in a gas flowing past the container. The water or the water vapor reacts with the phosphide particles as they become exposed to form phosphine. The phosphine, mixed with a carrier (usually air), may be fed into a duct connected to a grain silo, for fumigation of grain stored in the silo.

Formulations containing a phosphide for use in the controlled generation of phosphine

Fumigation of grain in a storage facility having a plurality of grain silos or bins is effected from a single source of a gaseous fumigant. The single source of gaseous fumigant is connected to a gas supply duct through which a carrier gas flows. The gas inlet ports of the silos are also connected to the gas supply duct. The connection between each gas inlet port and the duct is provided with a respective valve and a respective orifice plate, the orifice or aperture of which is sized so that the pressure drop across the orifice plate into the silo is substantially greater than the pressure drop across any other component between the gas source and the silo. With this arrangement, the flow rate of gaseous fumigant through the grain-containing silos in the facility suffers only a minor perturbation when a valve between the duct and a silo is opened or closed. This minor perturbation can be readily compensated by maintaining the gas pressure in the duct at a constant value. The exit gases of the silos in the facility may be recycled through the silos, with the addition of gaseous fumigant periodically or as necessary to maintain a predetermined fumigant concentration.

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Nambour, Australia

Robert Gordon Winks