The Preparation of High Purity Magnesium Oxide Part 1

NO 786/C REPORT No 786/С THE PREPARATION OF HIGH PURITY MAGNESIUM OXIDE PART 1. THE SEPARATION OF MICROQUANTITIES OF CALCIUM FROM MACROQUANTITIES OF MAGNESIUM A. DĘBSKA - HORECKA . T. PUKA5 . I. STROŃSKI KRAKOW report baa been reproduced directly from the best available copy Распространяет: ИНФОРМАЦИОННЫЙ ЦЕНТР ПО ЯДЕРНОЙ ЭНЕРГИИ при Уполномоченном Правительства ПНР по Использованию Ядерной Энергии Дворец Культуры и Науки Варшава, ПОЛЬША Available from: HUCLEAR ENERGY INFORMATION CENTER of the Polish Government Commissioner for Use of Nuclear Energy Palace of Culture and Science Warsaw, POŁAM) Drukuje i rozprowadza: OŚRODEK IflSOMfcACJl 0 EflSRGII JĄDROWEJ Pełnomocnika Rządu d/s Wykorzystania Energii Jądrowej Warszawa, Pałac Kultury i Wydaje Instytut Fizyki Jądrowej 520 1 7 ^*i •«*•:•••<**»*£ ark. wyd. 1-8 f Ark. druk. - , Dat! ** "Maszynopisu przez autora 10.1,1972 f Oddano do druku ,Druk ukończono X 71 ,SP-09/250/66, Zam. nr 12/72 THE PREPARATION OP HIGH PURITY MAGNESIUM OXIDE i. THE SEPARATION OF MICROQUANTITIES OP CALCIUM PROM MACROQUANTITIES 0,? MAGNESIUM PREPARATYKA TLENKU MAGNEZU O WYSOKIM STOPNIU CZYSTOŚCI i. ROZDZIELANIE MIKROILOŚCI WAPNIA CD MAIfflOILOŚCI MAGNEZU ПОЛУЧЕНИЕ ВЫСОКОЧИСТОГО ОКСВДА МАГНИЯ I. ОТДЕЛЕНИЕ МИКРОКОЛИЧЕСТВ КАЛЬЦИЯ ОТ МАКЮКОЛЯЧВСТВ МАГНИЯ Antonina DEBSKA-HORECKA, Tadeusz PUKAS Institute of Inorganic Chemistry and Technology, Technical University, Gliwice Ignacy STROŃSKI Laboratory of Chemistry and Radiochemistry, Institute of Nuclear Physics, Krakdw-Bronowic/e CRACOW, December, 1971 II The results of an investigation of processes of co-precipitation, crystallization, and liquid-liquid extraction of ions of calcium for the preparation of high purity salts of magnesium, by means of the ra- dioactive Isotope of Ca, are presented. fjj\ Ij]) Stosując promieniotwórczy izotop Ca badano proceey współstrącania, krystalizacji i ekstrakcji jonów wapnia w celu otrzymania soli magnezu o wysokim stopniu czystości. .Используя радиоактивный изотоп *^Са были исследованы методы соосаждении, кристаллизация и экстрак- ции ионов кальция с целю получения высокой чистоты солей магния. The main impurity of magnesium preparations, analytically pure (A.P.) J..s calcium (iO~2%). The fundamental problem in investigations concerning the preparation of high-purity magnesium oxide is, then, the removal of microquantities of calcium from the niacr©quantities of magnesium. The removal of trace anounts of calcium from magnesium compounds is connected with enormous difficulties, due to the fact that the magnesium and calcium belong to the same group of the periodic system, and because of the isomorphic structu- re of the correspondent compounds, eg. CaO and MgO both crystallize according to the regular pattern, and final- ly because of the occurrence of calcium in nature in large quantities, so that a secondary contamination of the magnesium preparations is always possible. From literature we know methods of separating calcium from magnesium, though in the majority of cases this concerns compounds in which the concentration of 1/ 2/ these tv?o elements is nearly equal ' * ' . The aim of this research was to investigate the effect of various methods of purifying magnesium pre- - 2 - parations from calcium, viz. a. by precipitating the macro-component in the form of a poorly soluble sediment in the presence of an agent complexing the raicro- oomponeut, b, by co-precipitating the micro-component together with the partial precipitation of the macro- component used as medium, с by crystallization, and d. by extracting the micro-component. Experimental The effect of purification was tasted radiometri- cally, applying the isotope Ca fa solution ol tho chloride Ca from the Radiochamical Centre at Amersham, with an activity of 1.9 ia'Ji/ml, Tt/2 = i36 days). For all the experiments an initial solution had been prepared (further on it will be called sample '7;, do that 10 ml 1 M A.P. magnesium nitrate was sampled and 0.05 ml Ca solution dropped in. The racUo- metric measurements were taken by теапз of an elec- tronic computer of the type LL-i and a G-M BAT-2 meter selecting for those measurements three 0.1 ml samples of the dried-out solution. The Eiean value of these reckonings made it possible to calculate the total activity. The sediments were solved in 10 ml - 3 - 2 М НС1, and the filtrates and organic phases were vaporized until a volume of 10 ml was reached» The magnesium was determined by complexometric 3/ tltration with sodium verse.nate '» a/ Precipitation of magnesium in the form of a poorly soluble sediment in the presence of a calcium completing agent. In order to separate the calcium ions from the magnesium ions the fundamental component was precipitated from the solution of 1 M magnesium nitrate in the form of hydroxide, carbonate, and oxalate. It was found that mopt of the calcium contained in the solution was co-precipitated together with the sediments (Table i) To prevent the co-precipitation of traces of calcium together with the sediment of magnesium hydroxide, various ' have suggested removing the magnesium hydroxide by means of basic sodium in the presence of sodium verenate so that the whole amount of calcium will be left in the solution* The suggested methods have been checked, with the modification that ammonium salt of ethylenediaminetetraacetio acid (EDTA) was used in order to eliminate the possibility of introducing additional impurities in the form of Na+ ions. Also ТаЪ1е_1 Co-proelpitatlon of trace amounts of ealolum nlta poorly soluble magnesium compounds 1 Radioactivity Degree of oounts/min ml precipita- of calcium tion of ma- No Vest co-precipi- gnesium in precipi- filtrate tated to- the sedi- tate gether with ment % the sediment i 2 Ъ 4 5 6 1 Precipitation of magnesium 6270±200 260^40 hxdroxide_with 2 If NaOH 96 39 la Precipitation of magnesium hydroxide with 2 U NaOH in 50-10 5280±120 1 99 the presence of EDTA 1b Precipitation of magnesium hydroxide with 2 M NaOH 60-18 4900^200 1 99 in the presence of EGTA 2 Precipitation of magnesium hydroxide by means of 4O±10 49ОО±16О 1 97 ammonia Table 1 1 2 3 4 5 6 3 Precipitation of magnesium 4840-128 carbonate 1100*96 81 98 I За Precipitation of magnesium СП carbonate in the presence 70*14 5400*172 1 90 I of EDTA ЗЪ Precipitation of magnesium carbonate in the presence 50*10 4500*160 1 98 of EGTA 4 Precipitation of magnesium 950*87 82 86 oxalate 4440-105 4а Precipitation of magnesium oxalate in the presence 20-10 4850*165 1 84 of EDTA 4b Precipitation of magnesium oxalate in the presence 10*10 4570*96 1 86 of EGTA Notes In test 1 - pH = 12.3, test 2 pH в 9.6, test 3 and 4 - pH = 9.3 - 6 - investigated «as the adaptability of БОТА as a calcium masking agent while the magnesium carbonate and magnesium oxalate are being precipitated. These compounds are more' advantageous in preparing MgO than magnesium hydroxide, due to the possibility of precipitating the easily washed out precipitates, Some authors 7~" *' have suggested using ethylene- glycolbisamino-ethyl-ether-tetra-acetic add (EGTA) as a reagent for the determination of calcium as compared with magnesium. Unlike magnesium in the range 7.5 - 8.5 pH calcium forms with EGTA a stable, negatively charged chelate; therefore an attempt was made to precipitate magnesium hydroxide, magnesium carbonate, and magnesium oxalate in the presence of EGTA. Attempts were also made to Isolate magnesium hydroxide by means of ammonia. The following tests were carried out: Precipitation of %(0H)2 by 2 M NsiOH To the sample W some drops of indigo carmine were added ; the whole was stirred while it was heated up to the boiling point} 2 U NaOH was gradually dropped In until the oolour changed from blue to yellow. The precipitate was left to settle, after which it was filtered and rinsed with hot H20. In the same way tests were carried out for samples la and lb (of. Table!), except - 7 - that 5 ml 0,15 M EDTA and 5 ml 0.15 M EGTA respectively were here added to the sample. Precipitation of Mg(0H)2 with ammonia 500 ml of A*P. 25% ammonia was placed in a desicc- ator 250 mm in diameter. Above the surface of the solution was placed a shallow polyethylene vessel 80 mm in diameter, containing the sample W. After 48 hours a sediment was obtained in the form of flakes. The sediment was rinsed with hot water. Precipitation of magnesium carbonate The sample W was brought to about 3.5 pH by 0,1 M ammonia; the whole was heated and 10 ml of 3 M ammonium carbonate were added, as well as 2 ml of con- centrated ammonia solution and 2 ml of ethyl alcohol. This was put aside until its temperature reached room temperature, and it was then filtered and rinsed with hot water. In the same way tests were carried out for samples 3a and 3b (Table 1), except that in this case to the samples being provided 5 ml 0,15 M EDTA and 5 ml 0.15 U EGTA respectively were added. Precipitation of magnesium oxalate The tests were carried out similarly as in the case of precipitating magnesium carbonate, applying 30 ml - 8 - of 0.5 U A* P. ammonium oxalate. Also the tests for samples 4a and 4b were carried out In this nay (Table 1), but to the sample W б ml of 0.15 M EDTA and 5 ml of 0.15 M SGTA were added respectively. The obtained results are assembled in Table 1. Investigations «ere aloo carried out concerning the co-preolpltation of calcium with magnesium hydroxide, aooordlng to the pH (Table 2). b. Co-precipitation of calcium ions Tilth the partial presipitatlon of magnesium as a collector Angelov et al.

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