GB865731A - Process and apparatus for separating phosphorus from gases - Google Patents

Abstract

<PICT:0865731/III/1> Gas containing phosphorus vapour from a phosphate-reduction furnace is sprayed with water in a first zone so as to cool the gas to a temperature of 55-65 DEG C., and precipitate not more than 99.5%, preferably 95-99.5%, of the phosphorus as a liquid, and in a second zone so as to cool the remaining gas to a temperature below the m.p. of phosphorus, and precipitate substantially all of the remaining phosphorus as a solid. The phosphorus precipitated in the second zone may be recovered by melting with live steam. The water sprayed to each zone preferably has a temperature of below 15 DEG C., e.g. 5-10 DEG C. As shown phosphorus-containing gas from the first zone, e.g. at a temperature of 55 or 60 DEG C., is injected from a line 21 into a second zone constituted by a tower 2, and is sprayed with water from nozzles 3. The resulting cooled gas, e.g. at a temperature of 10 DEG C., is passed through a pipe 9, the inlet of which is sprayed with water from a nozzle 22, a centrifugal separator 10 and a droplet separator 13, a phosphorus-water mixture being recycled to tower 2 via lines 24, 26 and 15. An aqueous phosphorus sludge separates in a lower conical part 4 of tower 2 and passes through a valve 6 into a sump 5 provided with steam line 7, molten phosphorus line 8, and deaeration line 25. Steam may be injected into sump 5 for a period of 2-3 hours. At intervals of 2 or more days. Supernatent water, e.g. at a temperature of 30 DEG C., is recycled via line 16, steam jet refrigeration plant 18, and line 19, together with make-up water from line 20, to nozzles 3 and 22.