The determination of potassium and sodium in coal ash

✍ Scribed by R. Belcher; A.J. Nutten; H. Thomas

• Publisher: Elsevier Science
• Year: 1954
• Tongue: English
• Weight: 631 KB
• Volume: 11
• Category: Article
• ISSN: 0003-2670
• DOI: 10.1016/s0003-2670(00)87705-3

✦ Synopsis

After the mixed chlorides of potassium and sodium have been isolated, potassium is determined by the pcrchloratc or chloroplatinate method and sodium by diffcrencc. In their work on the analysis of silicates and of rcfrnctories, MILLEH AND TRAVI& and HASLAM ANI) BEELEY~ showed that the cumbersome separations involved could be eliminated by determining potassium and sodium directly on suitable aliquots of the leachings. Potassium was separated as the cobaltinitritc and converted to the perchloratc, in which form it was finally weighed; sodium was determined gravimctrically as sodium zinc uranyl acetate. Thcsc methods appeared to be suitable for application to the analysis of coal ash, but further work based on the following considerations was nccessaxy : I. MILLEIZ AND Tn~vos (Zoc. cit.) reported that calcium caused positive errors in the sodium determination, unless a reprccipitation was carried out. HASLAM AND BEELEY (Zoc. cit.), however, made no refcrcncc to this interference, but the position was further complicated by other workers" who claimed that calcium caused negative errors.

2. DuVAL4 showed from thcrmopavimetric studies that sodium zinc uranyl acetate was not a satisfactory weighing form, as loss of water of crystallisation could occur at the dlying temperature used. I-Ie recommended instead ignition between 360" and 674" C to the stable double pyrouranate, &Na,U,O,.ZnU,O,. 3. The method for the determination of potassium was not convcnicnt because of the lengthy procedure involved. HASLAM AND BEELEY (lot. cit.) weighed the cobaltinitrite precipitate without further treatment when potassium was present in very small amounts, but in all other casts the precipitate owing to its variable composition had to be converted to the pcrchloratc.

Other matters which appeared to be worthy of further csamination were (a) the possibility of applying the flame photometer in the final determination of sodium and potassium and (b) the recent claim by LOGIE AND RAYNER~ that a temperature of 1000" C is necessary for the complete decomposition of certain ashes. Rcfcrc~rces p. r27. * Obtainable under the Trade Xame "Kal~gnost ' from Hoyl & Co., Chcm.: Pharm. Fabrllc, Berlin-Stcglltz v. Hildeshcim.