Abstract: Phosphorus pentasulfide is made. To this end gaseous nitrogen is introduced into the pipes feeding a reactor with a phosphorus melt and sulfur melt and/or into the outlet pipe for the phosphorus pentasulfide melt, the nitrogen being admitted under a pressure lower than the static pressure exerted in the pipes by the quantity of melt upstream of the gas inlets.

Abstract: The invention relates to a method for controlling and optionally regulating the level of liquid P.sub.2 S.sub.5 in a cooling device. To this end, an inert gas is introduced into the cooling apparatus arranged in inclined position. More particularly, the inert gas is introduced into the cooling apparatus' lower end portion through an inlet opening thereinto near a P.sub.2 S.sub.5 -feed inlet, and forced to bubble through the liquid P.sub.2 S.sub.5. The pressure difference which establishes in accordance with the P.sub.2 S.sub.5 liquid level in the device is measured and variations in the respective pressure difference are utilized for regulating the supply of liquid P.sub.2 S.sub.5 to the cooling device so as to maintain a predetermined liquid level therein.

Abstract: The invention provides a process and an apparatus for removing molten phosphorus pentasulfide, via an overflow, from a reactor, wherein phosphorus is reacted with sulfur at temperatures higher than 300.degree. C.To this end, the reactor is supplied with phosphorus and sulfur from dosing vessels which are given the dimensions necessary (a) to receive the quantity of phosphorus and sulfur, respectively, which are required to produce phosphorus pentasulfide with a preselected quantitative ratio of P:S, (b) to provide a total filling volume corresponding to that of a P.sub.2 S.sub.5 -receiving tank. The quantity of the phosphorus and sulfur feed materials in the respective dosing vessels is in each case fully emptied into the reactor and a corresponding quantity of molten P.sub.2 S.sub.5 is simultaneously discharged directly from the reactor, via the overflow, into the respective P.sub.2 S.sub.5 -receiving tank, whose filling volume exactly corresponds, to that of the dosing vessels.

Abstract: Phosphorus pentasulfide of low reactivity is made by solidifying molten phosphorus pentasulfide on a cooling cylinder that delivers the solidified product at a temperature of 150.degree. to 220.degree. C., and that product is immediately introduced into a heat-insulated container and freed therein from its immanent or sensible heat by cooling at a rate of at most 30.degree. C. per hour without the expenditure of any energy to control the cooling.

Abstract: The invention relates to an apparatus for making P.sub.2 S.sub.5 comprised of a plurality of reactors connected by pipe structures to a collecting tank which is common to all of them. By means of partitions, the cooling tank is subdivided into a plurality of separate chambers. Outlet pipes open thereinto and terminate in collecting devices. The pipe structures running to the collecting tank are pivotably arranged above the various chambers and permit liquid P.sub.2 S.sub.5 to be introduced thereinto at will.

Abstract: The invention relates to a method for controlling and optionally regulating the level of liquid P.sub.2 S.sub.5 in a cooling device. To this end, an inert gas is introduced into the cooling apparatus arranged in inclined position. More particularly, the inert gas is introduced into the cooling apparatus' lower end portion through an inlet opening thereinto near a P.sub.2 S.sub.5 -feed inlet, and forced to bubble through the liquid P.sub.2 S.sub.5. The pressure difference which establishes in accordance with the P.sub.2 S.sub.5 liquid level in the device is measured and variations in the respective pressure difference are utilized for regulating the supply of liquid P.sub.2 S.sub.5 to the cooling device so as to maintain a predetermined liquid level therein.

Abstract: The invention provides a process wherein a mixture prepared from starting materials comprised of P.sub.2 S.sub.5 of high reactivity and low reactivity, respectively, is converted to phosphorus pentasulfide of predetermined reactivity lying between that of the high reactivity P.sub.2 S.sub.5 and that of the low reactivity P.sub.2 S.sub.5 starting materials. To this end, the starting materials are mixed in quantitative proportions which are selected in accordance with the respective reactivity of the starting materials and the resulting mixture is ground.

Abstract: The reactivity of phosphorus pentasulfide produced by reacting phosphorus and sulfur at a temperature higher than the melting point of phosphorus pentasulfide and allowing the resulting melt to cool and solidify on a cooling device is improved. To this end, liquid phosphorus pentasulfide is placed on, or introduced into, a cooling device; an upper liquid P.sub.2 S.sub.5 -layer portion A is separated immediately from a solidified lower P.sub.2 S.sub.5 -layer portion B which is in direct contact with the cooling surface area of the cooling device; the upper P.sub.2 S.sub.5 -layer portion A is recycled to a P.sub.2 S.sub.5 melt; the lower P.sub.2 S.sub.5 -layer portion B is removed from the cooling device and collected as final product; the reactivity of the collected P.sub.2 S.sub.5 -layer portion B is increased to the same extent as the quantitative ratio of the P.sub.2 S.sub.5 -layer portion A to the P.sub.2 S.sub.5 -layer portion B is increased.

Abstract: Production of phosphorus pentasulfide from phosphorus and sulfur at elevated temperature in a reactor of which the walls are in heat exchange with a substance kept at the temperature necessary for cooling or heating reaction mixture.The heat exchange in the bottom portion of the reactor is more particularly effected with the use of a system functioning separately and independently from the heat exchange system surrounding the lateral walls of the reactor.