Reference

Chemistry of the secondary circuit of nuclear power plants with pressurized water reactors

Chemistry of the secondary circuit of nuclear power plants with pressurized water reactors. Operating experiences and developments. Heitmann, H. G.; Schub, P.; Seiffert, K.; Braun, D. (Kraftwerk Union A.Chemicals with cas numbers 7632-05-5 and 20344-49-4 also play role.-G., Erlangen, Fed. Rep. Ger.). VGB Kraftwerkstech., 64(1), 63-74 (German) 1984. CODEN: VGBKB5. ISSN: 0372-5715. DOCUMENT TYPE: Journal CA Section: 71 (Nuclear Technology) Section cross-reference(s): 61 In nuclear power plants with PWRs finished up to 1981, the steam generator water is conditioned with Na phosphate. In this case, the corrosion appears in the steam generator at the bottom of the tubes, which is caused by local attack by concd. salts. To prevent this corrosion, the AVT (all volatile treatment) management method was adapted, in which the remaining salts were largely removed by a special startup program following a cleaning of the tube bottom in the steam generator. Corrosion was brought practically to a stand still. In new plants the condensers are provided with austenite materials or Ti for piping. In this way, salt penetration can be completely avoided and corrosion product entry into the steam generator is substantially decreased by high alkalization with NH3 to pH >9.8. The Fe content in the feedwater during the operating period is 1-3 mg/kg. A further redn. is attainable by addnl. filtration of the feedwater. .

Recovering phosphate values from precipitates formed during the neutralization of impure wet process phosphoric acid

Recovering phosphate values from precipitates formed during the neutralization of impure wet process phosphoric acid. Grynkewich, Gregory W. (Olin Corp. , USA). U.S. US 4428915 A 31 Jan 1984, 6 pp. (English).In this study， 7664-38-2 and 7632-05-5 are also used. (United States of America). CODEN: USXXAM. CLASS: IC: C01B025-30. NCL: 423312000. APPLICATION: US 82-436225 25 Oct 1982. DOCUMENT TYPE: Patent CA Section: 49 (Industrial Inorganic Chemicals) The ppt. obtained during neutralization of wet-process H3PO4 with Na compds., contg. Al and Fe phosphates, is treated to recover the P2O5 values. The ppt. is treated with an aq. soln. contg. a Na compd. at pH 10-13 to ext. the P2O5 and part of the Al. The soln. contg. Na phosphate and dissolved Al is treated with a di(lower alkyl) b-diketone where the alkyl groups at the ends of the mol. are C1-4 alkyl. The metal chelate complex ppts. from the Na phosphate soln. and is removed. The Na phosphate soln. is treated to recover the P2O5 as Na2HPO4, Na3PO4, and Na5Si3O and Na5P3O10. Thus, a ppt. obtained when neutralizing wet-process H3PO4, contg. (dry wt.) P2O5 40.20, Mg 0.84, Ca 3.50, Al 3.80, Fe 8.03, and Na 9.25% was mixed with 50% aq. NaOH and filtered. The filtrate contg. P2O5 2.3, Na 2.5, Fe <0.0015, and Al 0.40% was treated with acetylacetone to give a ppt. which was Al acetylacetonate and a filtrate contg. 2.2, 2.3, < 0.0015, and 0.045%, resp. This filtrate is extd. with benzene and treated with activated C to give a soln. contg. 2.1, 2.3, <0.0015, and 0.0040%, resp. .