Determination of minerals in platinum concentrates from the Transvaal by X-ray methods

1932 ◽  
Vol 23 (138) ◽  
pp. 188-206 ◽  
Author(s):  
F. A. Bannister
Keyword(s):  
Solid Solution ◽  
New Mineral ◽  
Early Analysis ◽  
Aqua Regia ◽  
X Ray ◽  
Ray Methods ◽  
Platinum Mineral ◽  
Insoluble Portion

Concentrates from the platiniferous norites of the Bushveld, Transvaal, are not completely soluble in aqua regia. The insoluble portion consists of steel-grey fragments first analysed chemically by R. A. Cooper and considered by him to be a new platinum mineral represented by the formula Pt(As,S)2. The name cooperite was proposed for the new mineral by F. Wartenweiller, and after further work Cooper decided that the arsenic found in the early analysis was due to the presence of sperrylite, and he changed the formula to PtS2. H. Schneiderhöhn observed simple twinning and, less frequently, polysynthetie lamellae on polished sections of mineral grains from the same deposits, and he suggested that cooperite is probably orthorhombic and isomorphous with marcasite. The latest account of the new mineral has been published by H. R. Adam who gave several analyses of cooperite from the Rustenburg and Potgietersrust districts and concluded that the ‘mineral is PtS2 with a small amount of excess metal (platinum, palladium, and nickel) present in solid solution’.

Detection Confirmation and Determination of Trace Amounts of Selenium by X-Ray Methods

1963 ◽  
Vol 7 ◽  
pp. 542-554
Author(s):  
Frank L. Chan
Keyword(s):  
Matrix Effects ◽  
Hexagonal Structure ◽  
Elemental Selenium ◽  
X Ray Diffraction ◽  
X Ray ◽  
Yellow Color ◽  
The Matrix ◽  
Ray Methods ◽  
Tetravalent State

AbstractRecently, interest in the determination of selenium in trace amounts has been greatly intensified because of the nutritional aspects of this element. It has been reported that selenium in the amount of 13 μg in the form of sodium selenite in 100 g of feed has an effect similar to that of vitamin E. In the field of semiconductors, the detection and determination of trace amounts of selenium in arsenic, antimony, and small single crystals of solid solution of cadmium selenide and sulfide are of considerable importance in semiconductor performance.In the Aerospace Research Laboratories, 4,5 diamino-6-tbiopyi-imidine has been successfully adopted as a reagent for the spectrophotometric determination of selenium. The reaction of 4,5 diamino-6-thiopyrimidine and tetxavalent selenium produces a yellow color with the formation of elemental selenium. It is possible to determine elemental selenium by collecting it in a thin layer. The selenium deposited in this layer may then be determined by an X-ray fluorescence method. A procedure of this nature has the advantage of eliminating the matrix effects commonly encountered in X-ray fluorescence. Furthermore, the slow generation of selenium affords a convenient means of detection and confirmation of this element by the use of X-ray diffraction procedures. By this technique selenium is first converted to its tetravalent state and is then reacted with 4,5 diamino-6-thiopyrimidine. On standing, the selenium is reduced to a red precipitate of elemental selenium which can be dissolved in carbon disulfide. Finally, the selenium can be converted into its hexagonal structure by annealing at 205-207°C.

scholarly journals Prediction of As, Cd, Cr, Hg, Ni, and Se Concentrations in Organic Amendments Using Portable X-ray Fluorescence and Multivariate Modeling

2020 ◽  
Vol 10 (17) ◽  
pp. 5726
Author(s):  
Rafael López-Núñez ◽  
Fátima Ajmal-Poley ◽  
Pilar Burgos-Doménech
Keyword(s):  
Organic Amendments ◽  
Linear Functions ◽  
Organic Fertilizers ◽  
Regression Equations ◽  
Sewage Sludges ◽  
Aqua Regia ◽  
X Ray ◽  
Exchange Programme ◽  
Analytical Laboratories

Portable X-ray fluorescence (pXRF) has been a widely used technique in various applications. However, its use for the analysis of organic amendments (composts, sewage sludges, organic fertilizers) is scarce. In these matrices, concentrations of some elements are below their detection limit. The objective of this work was to find multiple linear regression equations that were able to predict the aqua-regia-soluble concentrations of the elements As, Cd, Cr, Hg, Ni, and Se using the pXRF readings of other measurable elements as predictor variables. For this, a set of 30 samples of organic amendments (composts, sewage sludges, and organic fertilizers) from the Manure and Refuse Sample Exchange Programme of the Wageningen Evaluating Programs for Analytical Laboratories (MARSEP-WEPAL) was used. Several amendment type-dependent single or multiple linear functions were found based on 1, 2, or 3 predictors. The predictor readings corresponded to the concentration of elements of geogenic (Fe, Si, Ti, Cl, Zr Al, Ca, S, Mn, and Ba), anthropogenic (Zn and Pb), and agricultural (P and K) origin. The regression coefficients of these functions were r = 0.90–0.99; therefore, they allowed for the quantitative determination of the target elements. These results will allow for fast and reliable analysis of organic amendments using pXRF that is valid for quality control in treatment plants.

scholarly journals Crystallographic studies of meteoric iron

1939 ◽  
Vol 238 (794) ◽  
pp. 393-421 ◽  
Keyword(s):  
Crystal Structures ◽  
X Ray ◽  
Cubic Lattice ◽  
Principal Axes ◽  
Ray Methods

The first study of meteoric iron by X-ray methods was undertaken at the instigation of Professor S. W. J. Smith, F.R.S. some years ago. This research (Young 1926) resulted not only in the determination of the crystal structures of two of the main constituents, kamacite and taenite, but also in the important discovery of the nature of the mutual orientations of these constituents when the meteorite exhibits a Widmanstätten structure. As is well known, the Widmanstätten figures in meteorites arise from the arrangement of kamacite lamellae on the planes of an octahedron, and for that reason a meteorite exhibiting these figures is generally referred to as an octahedrite. The kamacite lamellae, therefore, fix the {I I I}-planes of a hypothetical cubic lattice whose principal axes, XYZ , will be referred to as “ the axes of the octahedrite”.

Determination of the thickness of polycrystalline thin films by using X-ray methods

2015 ◽  
Vol 591 ◽  
pp. 215-218 ◽  
Author(s):  
S. Daniš ◽  
Z. Matĕj ◽  
L. Matĕjová ◽  
M. Krupka
Keyword(s):  
Thin Films ◽  
X Ray ◽  
Polycrystalline Thin Films ◽  
Ray Methods
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