Alloying elements in mineral and synthetic components of welding materials

New naturally alloyed components of welding materials (sphene, nepheline, and titanium-magnetite concentrates from apatite-nepheline ores from the Khibiny deposit), synthetic components based on concentrates of olivine ores from the Khobozero deposit, and also hydroxides and xerogels are considered as precursors of new alloyed components.     

A case study of the ambient oxidation of two zinc-lead (sulphide) reference ores

The history of two lead-zinc (sulphide) reference ores is presented to show quantitatively the serious effects of ambient oxidation on unprotected samples. This study should serve as a warning to the users and producers of sulphide-bearing reference ores and concentrates. Suggestions are given for overcoming or diminishing the oxidation problem.     

A new catalytic reaction of rhenium and its analytical application

Small amounts of perrhenate in fairly concentrated sulphuric acid media and in the presence of tin(II) chloride are found to catalyse the acid hydrolysis of alpha-furildioxime, with production of a new absorption peak at 320 nm, due to the di-alpha-furildiketone produced. The catalytically active species is a sulphate complex of rhenium(IV). The catalytic action of rhenium is promoted by citric acid. Rhenium can be determined in the range 0.0005-0.5 mug/ml. Interferences are eliminated by a preliminary extraction. The method has been applied to the determination of rhenium in copper concentrates of low rhenium content, copper ores and rocks. On the basis of the inhibitory effect of molybdenum the reaction can be used for determination of this element as well.     

Decomposition of ores by manganese dioxide Analysis of copper ores and concentrates

Manganese dioxide in presence of sulphuric acid has been used for the decomposition of copper ores and concentrates for determination of copper and iro.     

X-ray fluorescence analysis of metals in ores and concentrates by Compton scattering

An X-ray fluorescence method for the analysis of ores and concentrates for one or more metals or other heavy elements is described. A tungsten-target tube is used and the spectral interference of Rayleigh and Compton scattered peaks reduced by a nickel filter. A correlation is established between the latter peak intensity and the mass absorption coefficient of the sample for the wavelength 1.6 Å. The values of mass absorption coefficients on both sides of any major element absorption edge are compared and their ratio correlated to the characteristic radiation intensity of that particular element. This permits calculation of mass absorption coefficients across major absorption edges by derivation from the measured μ 1.6 value. Spectral interferences and other difficulties advocate dilution of the samples with dipotassium disulfate. Element concentrations are calculated by comparison with a standard sample and relating mass absorption coefficients and characteristic radiation intensities of both standard and unknown. Precision and accuracy of the method are considered excellent, given the simple nature of the analytical procedure.     

The determination of silver in ores by anodic stripping voltammetry

Stripping voltammetry at a rotating glassy carbon electrode is proposed for the determination of silver in ores. The ores or concentrates are dissolved in suitable acid mixtures, and silver is separated either by extraction with dithizone in carbon tetrachloride, or by adsorption on silica from ammoniacal buffered solution and subsequent elution with 0.1 M nitric acid. The results obtained with stationary and rotating glassy carbon electrodes are discussed. Stripping voltammetry and fire assay give results in reasonably good agreement.     

IR spectral determination of mica in multicomponent systems

A procedure for the determination of mica (muscovite) in ores and concentrates by IR spectrometry is developed. It is shown that the change in the absorbance of the muscovite OH group band at 3620 cm^?1 allows a calibration plot to be constructed for the determination of 1–90% muscovite.     

Use of Chelex 100 in determination of bismuth in sulphide ores, concentrates, metals and alloys

In the determination of bismuth, Chelex 100 has been successfully employed for reducing the concentration of matrix and interfering elements from sulphide ores and concentrates and for separation of the matrix elements from bismuth in the analysis of high-purity copper, silver and silver-cadmium alloy.     

A multi-element serum standard for neutron activation analysis

An annular ²²⁷AcBe isotopic neutron source, containing 6.6-Ci ²²⁷Ac, is described for application in fast and thermal neutron activation analysis, with high accuracy, for major constituents in ores, alloys and industrial concentrates. The characteristics of the neutron output and of the fast, epithermal and thermal flux and flux gradients is described in detail. The determination of manganese in pyrolusite ores and ferro-manganese is compared to results obtained previously with a cylindrical 1-Ci ²²⁶RaBe source. Two new sources of systematic errors have been discovered.     

An experimental evaluation of neutron activation, wet assay and fire assay methods of determining gold in ores

The errors associated with fire assay, wet extraction and neutron activation methods are evaluated, the accuracy and precision of these methods are compared, and a method of determining chemical recovery in the activation determination of gold in ores and concentrates is presented.     

Determination of silver in ores and metallurgical concentrates by a combination of fire-assay preconcentration (using tin as collector) and atomic-absorption spectrophotometry

A new method is described for the determination of silver in ores and metallurgical concentrates. The procedure is based on collection of silver in a tin button during a fire assay fusion, and the subsequent determination by atomic-absorption spectrophotometry. The proposed method is rapid and free from inter-element interferences, and results obtained agree favourably with those obtained by alternative methods.     

Spectrophotometric method for assessing oxidation of chalcopyrite-bearing ores and concentrates

The short-term oxidation of chalcopyrite ores and concentrates, during storage, can be monitored by measuring the absorbance of the purple Cu(I)-biquinoline complex that is formed when powdered samples are agitated directly with a water-acetone solution of 2,2'-biquinoline.     

Oxidation of sulphide minerals--II: determination of metal in the oxidation products of galena, sphalerite and chalcocite

A 15% ammonium acetate and 3% acetic acid solution has been shown to be useful in the determination of the principal metal in small amounts of the oxidation products of galena, sphalerite and chalcocite. Its use in the determination of the extent of oxidation in concentrates or complex ores of these minerals is implied.     

Thermal behaviour of Estonian phosphorites from different deposits

Journal of Thermal Analysis and Calorimetry - Thermal behaviour of shelly Estonian phosphorite ores from Iru, Toolse, Ülgase deposits and their concentrates have been studied. The...     

Substoichiometric determination of rhenium in copper ores and molybdenum concentrates by neutron activation analysis

A simple and rapid substoichiometric method is described for the estimation of rhenium in copper ores and molybdenum concentrates by neutron activation analysis. 2 μg of Re can be determined with an accuracy of 4%. The variation of the mean at 95% confidence limit does not exceed 2%. The time required for processing three samples is less than 60 min.     

A critical review of the volumetric methods for the platinum metals

The published methods for the volumetric determination of the six platinum metals have been appraised. The lack of generally applicable and accurate methods is emphasized. No volumetric method has been recorded for the direct application to solutions of platinum metals, ores, concentrates or natural alloys, and only a few for determinations in synthetic alloys such as fire assay beads. Volumetric methods for the platinum metals are characterized by the absence of data concerning methods of dissolution.     

Fractionation of Sulfur Isotopes in the Course of High-Temperature Roasting of Copper-Nickel Sulfide Ores and Concentrates

The fractionation of sulfur isotopes, namely, enrichment of the cinder with the heavy isotope ³⁴S in the course of roasting of various sulfide ores and concentrates in neutral and oxidative atmospheres at 773-973 K was studied.     

Spectrophotometric determination of germanium in ores, concentrates, zinc-processing products and related materials with phenylfluorone and cetyltrimethylammonium bromide after separation by iron collection and heptane extraction of germanium tetrachloride

A method for determining approximately 0.2 microg/g or more of germanium in ores, concentrates, zinc-processing products and related materials is described. The sample is decomposed by fusion with sodium peroxide and the cooled melt is dissolved in dilute sulphuric acid. Silica, if > 50 mg, is removed by volatilization with hydrofluoric acid. Germanium is separated from sodium salts by co-precipitation with hydrous ferric oxide, the precipitate is dissolved in 3M hydrochloric acid and germanium is subsequently separated from iron(III) and other co-precipitated elements by a single heptane extraction of germanium tetrachloride from approximately 9.4M hydrochloric acid. The extract is washed with 12M hydrochloric acid to remove residual iron(III), then germanium is stripped with water and determined spectrophotometrically with phenylfluorone in a 1.4M hydrochloric acid-0.002M cetyltrimethylammonium bromide medium in the presence of ascorbic acid as a reductant for co-extracted chlorine. The apparent molar absorptivity of the complex is 1.71 x 10(4) l.mole(-1).mm(-1) at 507 nm, the wavelength of maximum absorption. Up to 5 mg of tin(IV), 10 mg of antimony(V) and tungsten(VI) and approximately 50 mg of silica do not interfere. Germanium values are given for some Canadian certified reference ores, concentrates and iron-formation samples and for a metallurgical dust.     

Application of fluoroxidants for the decomposition and analysis of platinum metals and gold in black shale ores

In order to develop a reliable method for the platinum group metals (PGMs) determination in ores of organic origin like carbonaceous black shale a decomposition method with fluoroxidants like BrF₃ and KBrF₄ was established which avoids the commom losses of PGM organometallic compounds by volatilazation or chemisorption. The recovery from different trapping solutions is discussed. Platinum metals are evidently found in the carbonaceous black shale ores from the “Natalka” deposit situated in the Magadan area. PGMs are very inhomogenously distributed in the ores and ore concentrates and their total contents in ore are 5–18 g/t. The carbonaceous concentrate of black shale ore contains up to 23 g/t of the sum of platinum metals. ≥ 8% of the sum of platinum and palladium contained in this carbonaceous concentrate are soluble in organic solvents. Received: 16 July 1998 / Revised: 16 April 1999 / Accepted: 5 May 1999     

Application of fluoroxidants for the decomposition and analysis of platinum metals and gold in black shale ores

In order to develop a reliable method for the platinum group metals (PGMs) determination in ores of organic origin like carbonaceous black shale a decomposition method with fluoroxidants like BrF₃ and KBrF₄ was established which avoids the commom losses of PGM organometallic compounds by volatilazation or chemisorption. The recovery from different trapping solutions is discussed. Platinum metals are evidently found in the carbonaceous black shale ores from the “Natalka” deposit situated in the Magadan area. PGMs are very inhomogenously distributed in the ores and ore concentrates and their total contents in ore are 5–18 g/t. The carbonaceous concentrate of black shale ore contains up to 23 g/t of the sum of platinum metals. ≥ 8% of the sum of platinum and palladium contained in this carbonaceous concentrate are soluble in organic solvents. Received: 16 July 1998 / Revised: 16 April 1999 / Accepted: 5 May 1999