Abstract: The invention relates to process for making phosphorus pentoxide by subjecting elementary phosphorus to a combustion reaction with the aid of air, the reaction heat being utilized for the production of energy. To this end, the invention provides for the phosphorus to be subjected to combustion with dry air containing, per m.sup.3, 5 g down to 0.01 g of water, inside a combustion chamber of which the metallic walls are arranged so as to form a cooling system with cavities therein and for a liquid and liquid/steam-mixture, respectively, to be circulated through the cooling system under pressure within the range 1 to 150 bars, the liquid or mixture assuming a temperature of more than 150.degree. C. up to 500.degree. C. Steam which is formed in the cooling system is continuously taken therefrom and replaced by an equivalent proportion of fresh liquid.

Abstract: The invention relates to an arc furnace roof. The roof is comprised of a metal cover which is bolt-connected to the furnace shell. Secured to the lower side of the cover is a plurality of shackle hooks, each of said shackle hooks having an anchor bolt hooked therein. The metal cover has a first layer of insulating concrete applied to its lower side and a second layer of refractory concrete applied to the hard first layer of insulating concrete, the two layers of insulating and refractory concrete, respectively, embedding the shackle hooks and anchor bolts.

Abstract: The invention relates to a process for operating a lead-in-device receiving a conductor which passes through the cover of an electrical precipitation apparatus down to its electrode system. A portion of the conductor is encircled by an insulator which is radially spaced therefrom and of which the upper end provides support for a structural component having the conductor gas tightly passed therethrough. The space inside the insulator receives a sealing gas which is maintained under a pressure higher than that prevailing in the electrical precipitation apparatus. The sealing gas used for operating the device is a gas mixture consisting of an inert gas and at least 10 volume % of methane.

Abstract: Hexagonal phosphorus pentoxide is made in an apparatus comprising a combustion chamber (1) which has a plurality of cooling pipes (10) disposed at its inside wall and is connected through a gas cooler (3) to a condensation chamber (4), the gas cooler (3) comprising a system of cooling pipes (5) which terminate, similarly to an open immersion tube, above the bottom portion of the condensation chamber (4), whose walls are provided with a cooling device (6).