The vapour pressures of various salts have been investigated at high temperatures and the results are presented here together with the values found by previous investigators. Sodium sulphate is extensively used in the glass producing industry and it is in this compound that interest is centred. Other salts have been included in this study for the purpose of comparison. The use made of sodium sulphate in glass making is discussed briefly below. Work previously reported on the determination of the vapour pressure of sodium sulphate will be shown to have produced confusing results, and it was for the purpose of introducing some harmony into the sometimes discordant evidence that the present work was undertaken.

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The extraction of the Rare Earths from two kilograms of Lindsay Light and Chemical Company's "monazite residues" (hydrated Rare Earth oxides), from two kilograms of Norwegian gadolinite, and from five kilograms of Lindsay's "didymium carbonate" (Code 411) gave a mixture of Rare Earths which, after purification, fractional crystallisation as the double magnesium nitrates and ion exchange separation, showed some evidence for the existence of naturally occurring element number 610. This evidence took the form of unexplained lines in the arc spectra, anomalous absorption bands, aid an unexplained peak in the elution curve obtained from the ion exchange work. The evidence presented is far from conclusive and the suggestion is made that further research along these lines be carried out. / Science, Faculty of / Chemistry, Department of / Graduate

Rare earth elements, (REE), at ug g⁻¹ levels are used for studies of petrogenisis of different geological materials. For these studies, the REE must be determined precisely. An analytical program was established using an IL 200 Inductively Coupled Plasma, (ICP), spectrometer for the determination of the REE in various matrices, taking into consideration both matrix and spectral interferences, which were found to be severe in some cases. Dissolution of the sample, (0.4-1.0 g), was carried out using two methods; a microwave heated dissolution using a modified commercial microwave oven and a conventional oven heated closed pressure digestion vessel method. The results of these two methods were compared to determine the viability of using the more rapid microwave heated method. Separation of the REE from matrix elements was investigated using three cation exchange resins; Amber lite IR 120 (H), Zeocarb 225 and Dowex 50-WXS. A gradient acid elution method was established using a 15 cm by 20 mm Zeocarb 225 column. The sample was eluted with 140 ml of a 1.5 M H⁺ solution containing 0.75 M Cl⁻ and 0.75 M NO₃⁻, this fraction containing all the matrix elements. The REE were then eluted from the resin with 100 ml of 3 M HNO₃. The REE containing fraction was then reduced to 5 ml, diluted to 10 ml, and analysed for REE content. Liquid-liquid extraction methods for the separation of REE from matrix elements were investigated. It was found that the REE could be extracted synergistically from various buffered aqueous acidic media into chloroform, (CHCl₃), by hexafluoroacetylacetone, (HHFA), and quinoline. Acetylacetone, ( AcAc), was found to react with hexamethylenetetramine, (hexamine), when hexamine was used to buffer the aqueous phase during extraction procedures. The product of this reaction, 3.5-diacetyl-1.4-dihydro-2.6-dimethyl pyridine, was identified using X-ray crystallography.

A research report submitted in partial fulfillment of the requirements for the degree of Masters of Science in Economic Geology (Course Work & Research Report) to the Faculty of Science, University of Witwatersrand, Johannesburg, 2019 / The Epembe carbonatite dyke at the Epembe Carbonatite-Syenite Complex in the Kunene region on the northwestern border of Namibia was emplaced along a northwest-trending fault zone, into syenites and nepheline syenites and extends for approximately 6.5 km in a northwest to southeast direction with a maximum outcrop width of 400 m. The Epembe carbonatite has a Mesoproterozoic age of 1184 ± 10 Ma which is slightly younger than their host nepheline syenites (1216 ± 2.4 Ma). Following the geological data collection and laboratory analysis of whole-rock samples [using optical microscopy, X-ray fluorescence (XRF) and inductively coupled plasma mass spectrometry (ICP-MS)] the collected data was studied in detail in order to determine the geochemical composition of the Epembe carbonatite dyke. This research therefore presents new geochemical data for the Epembe carbonatite in order to describe the distribution and occurrence of rare earth elements of this dyke. The carbonatite displays a heterogeneous characteristic both texturally and mineralogically highlighting clear successions of at least three magmatic pulses. Irrespective of the changes, all carbonatite phases are inferred to be sourced from the same magma because they are typified by a similar geochemical signature of both major and trace element composition. They are characterised by high concentrations of calcium (CaO: 38.01 - 55.31 wt. %), phosphorus (P) (up to 18076), titanium (Ti) (up to 5122 ppm) strontium (Sr) (up to 12315 ppm) and niobium (Nb) with the (highest value of up to 2022 ppm ) alongside low concentrations of iron (FeO: 0.87 - 9.29 wt. %), magnesium (MgO: 0.19 – 1.33 wt. %) silica (SiO2: 1.30 – 10.89 wt. %) and total alkalis (K2O + Na2O < 2.0 wt. %) , hence they are regarded as one carbonatite dyke. The petrography and whole-rock element compositions of major elements have demonstrated the Epembe carbonatite is primarily made up of course-grained calcite (~92%) with a CaO+MgO+Fe2O3+MnO ratio of 0.93 relative abundances (in wt. %) and thus is classified as calcio or calcite carbonatite. The total REE content of Epembe carbonatite is high (406 – 912 ppm) with high LaN/YbN value (10.19 -28.49) and thus atypical of calcio-carbonatites. Chondrite normalized REE pattern for the carbonatite exhibit a strong steady decrease (negative slope) from LREEs to HREEs with a slight negative Eu anomaly but those are relatively low compared to global average calcio-carbonatites. Even though the Epembe carbonatite is enriched in Rare Earth Elements, there were no REE-bearing minerals observed at Epembe carbonatite except for monazite in trace amounts. Geochemical results show that the REE are either included in several accessory minerals such as apatite and pyrochlore and possibly in gangue minerals (i.e., silicates [including calcite and zircons] and carbonates) through enrichment processes related to fractional crystalisations and chemical substitution. / TL (2020)

No description available.

No description available.

Thesis (Master)--İzmir Institute of Technology, İzmir, 2004. / Includes bibliographical references (leaves. 50-54).

No description available.