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: 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 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.