The determination of metallic iron,nickel and cobalt in reduced ores and oxides

A procedure is described for the determination of metallic iron, nickel and cobalt in reduced ores and oxides. The metallic phases are dissolved in brominemethanol solution, excess of bromine is destroyed by reaction with hydroxylamine hydrochloride and the analysis is completed by atomic absorption spectrophotometry. Solution of oxide phases is not observed if free or combined water is removed from the samples. Results are presented for an ore and standard alloys.     

Rapid photometric determination of phosphorus in iron ores and related materials as phosphomolybdenum-blue

A rapid, simple and accurate method for determining phosphorus photometrically in iron ores and related materials, obviating the use of perchloric acid, is described. The sample is fused with sodium peroxide in a zirconium crucible and the melt dissolved in hydrochloric acid. The molybdenum-blue complex is developed by the addition of ammonium molybdate and hydrazine sulphate and the absorbance is measured at 725 nm. The range of the method is from 0.005 to 1.0% P. A batch of 6 samples can be analysed in about 2 hr.     

Rapid method for total iron determination in iron ores, sinter and related materials without use of mercury compounds

A rapid method for determining total iron in iron ores, sinter and related materials without use of mercury compounds is described. Fusion of the sample with sodium peroxide in a zirconium crucible and subsequent treatment with acid yields total decomposition and a solution amenable to direct reduction to ferrous iron with a silver reductor and subsequent titration with dichromate. Results for NBS, BCS and ISO reference standard ores demonstrate the universal applicability of the method both for routine and referee analysis. There is no interference from vanadium and two samples can be analysed in 30 min.     

Rapid volumetric method for the estimation of iron in presence of interfering ions

Summary It has been shown that in the photochemical reduction method for the volumetric estimation of iron, there is no interference by chromium, titanium, tungsten, molybdenum, manganese, cobalt, nickel and fluoride. This method is therefore recommended for a rapid determination of iron in alloys and ores without the elimination of these interfering ions. Vanadium, however, was found to give slightly higher values for iron.Our thanks are due to Prof. G.Gopala Rao for his kind interest in the work.     

Silver-reductor method for determination of iron in iron ores and iron-ore sinters

A new technique for the quick dissolution of iron ore, magnetite and sinter products has been developed. The sample is dissolved with thioglycollic acid and hydrochloric acid, the excess of thioglycollic acid is oxidized, and the iron is reduced in the silver reductor.     

Synthesis of iron oxide cubes/reduced graphene oxide composite and its enhanced lithium storage performance

Fe₃O₄ is considered as a promising electrode material for lithium-ion batteries(LIBs) due to its low cost and high theoretical capacity(928 mAh/g).Nevertheless,the huge volume expansion and poor conductivity seriously hamper its practical applications.In this study,we use a facile hydrothermal reaction together with a post heat treatment to construct the three-dimensional heterostructured composite(Fe₃O₄/rGO) inwhich reduced graphene oxide sheets wraped the Fe₃O₄ submicron cubes as the conductive network.The electric conduction and electrode kinetics of lithium ion insertion/extraction reaction of the composite is enhanced due to the assist of conductive rGO,and thus the Listorage performance is obviously improved.The composite exhibits a reversible charge capacity of772.1 mAh/g at the current density of 0.1 A/g,and the capacity retention reaches 70.3% after400 cycles at0.5 A/g,demonstrating obviously higher specific capacity and rate capability over the Fe₃O₄ submicron cubes without rGO,and much superior cycling stability to the parent Fe_2 O_3 submicron cubes without rGO.On the other hand,as a synergic conductive carbon support,the flexible rGO plays an important role in buffering the large volume change during the repeated discharge/charge cycling.     

Determination of calcium oxide in calcined phosphate ores

It has been shown that an existing procedure to differentiate calcium oxide from the carbonate and silicate of calcium can be used in the presence of the phosphate, fluoride and sulphate of calcium, and of the carbonate and oxide of magnesium. It is based on the reaction in aqueous solution of calcium oxide with sucrose to form calcium saccharate, and subsequent titration with oxalic acid solution. The method has application for a direct chemical determination of calcium oxide in phosphate rock where calcination of accompanying carbonate is necessary in beneficiation processes.     

Rapid chelatometric estimation of chromium, iron and aluminium in chromium + iron and chromium + aluminium mixtures

Summary A study of the kinetics of the reaction of chromium(III) with EDTA [1,2] had shown that the rate of reaction, usually slow, can be accelerated in the presence of hydrogen carbonate, sulphite, nitrite and organic solvents like alcohols, ketone, dioxane, etc., or suppressed in the presence of oxalate, acetate, etc. Based on this principle, a rapid titrimetric method using EDTA was developed for the estimation of chromium(III), iron and aluminium in chromium(III) + iron and chromium(III) + aluminium mixtures. The method has been extended for the estimation of iron and chromium(III) in stainless steel. Results are satisfactory.

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Zusammenfassung Die Reaktion von Chrom(III) mit äDTA kann durch Hydrogencarbonat Sulfit, Nitrit sowie organische Lösungsmittel beschleunigt oder durch Oxalat, Acetat u. a. unterdrückt werden. Aufgrund dieser Erscheinung wurde ein chelatometrisches Verfahren zur Bestimmung von Chrom(III), Eisen und Aluminium in Gemischen von Cr + Fe oder Cr + Al ausgearbeitet, das auch auf die Bestimmung von Eisen und Chrom in rostfreiem Stahl angewendet wurde. Es wurden befriedigende Ergebnisse erhalten.

     

Routine analysis of iron ores by X-ray spectrometry

A number of iron ores from all parts of the world were analysed with a powder sample preparation technique. Calibration curves were plotted for Fe, Ca, Si, Al and Mg in wide concentration ranges using 32 international and a few local standards. All iron ores were divided into 5 groups related to mineralogical differences; however, the calibration curve for Ca is common for all samples. For hematites and magnetites the relationship FeO + Fe₂O₃ = f(Fe) was experimentally established. The total time for sample preparation and analysis is about 5 min. A good correlation of chemical and X-ray results was obtained in this routine work.     

Rapid determination of thorium in ores : Estimation of trace amounts of thorium in complex minerals and ores

A very rapid method for the estimation, of trace amounts of thorium up to 0.01 per cent. or thereabouts even in complex minerals like ilmenite and columbitetantalite has been described. Thorium is collected in an acid solution with phosphates of zirconium and titanium without prior separation of silica, after decomposition of the mineral with sodium peroxide. Thorium is next collected as fluoride with lanthanum as a carrier, precipitated as thorium iodate in potassium iodate-oxalic acid mixture and finally titrated against 0.01N sodium thiosulphate. Accurate results are obtained within a short time of two working days.     

原位自动光度滴定法测定铁矿中铁含量

利用自动电位滴定仪和DP5光度电极研究了原位自动光度滴定法在全铁测量中的应用。以HNO3、HCl和HF溶液为溶剂,采用密封微波消解系统分解试样。用NaOH溶液调节溶液酸度至pH 1.5,在原消解罐中以乙二胺四乙酸二钠盐(磺基水杨酸为指示剂)滴定铁。主要对滴定温度、试样的分解条件以及杂质对测定的干扰情况进行了研究。研究结果表明,称样量为0.05 g,溶剂为60%王水10 mL加1 mL HF(1+99),温度为210℃,消解时间为20 min时溶样效果最好,50～60℃条件下,pH 1.5时进行滴定,结果准确可靠,能有效消除干扰。     

Area-selective microscale metallization on porous anodic oxide film of aluminium

A new method for micropatterning of metallic patterns on porous anodic oxide film of aluminium is described. The porous anodic oxide film was impregnated with organic dye and palladium ions before the hydrothermal pore-sealing. The surface layers formed during the pore-sealing, i.e. outer acicular hydroxide layer and a compact intermediate sub-layer trap the palladium ion underneath the layers. Exposing the palladium enriched area by the help of laser beam followed by electroless nickel deposition results the deposition of nickel on the laser-exposed part. Thickness of the deposits can be up to about 2–3 μm, after about the 20 min of immersion in electroless nickel plating bath. The metallic micropatterns, formed by the method are crack free, smooth and uniform over extended length.     

Precise coulometric determination of iron in iron ores with electrogenerated manganese(III) fluoride

Iron in Mohr's salt, electrolytic iron and iron ores has been determined by precision coulometric titration with electrolytically generated manganese (III) fluoride, with biamperometric end-point detection. The titration curve indicated the irreversibility of the electrode reaction of manganese(III) fluoride. Total iron in several standard samples of iron ores was determined with standard deviations of about 0.012%.     

Unified automated determination of silicon in iron ores, sinters, slags, iron and steel

An automatic absorptiometric method is presented for the determination of silicon in iron ores, sinters, slags, iron and steel. The last two are dissolved in dilute sulphuric acid; the others are fused with sodium peroxide, then dissolved in hydrochloric acid. After suitable additions and dilution, the resulting solutions are treated identically in a Technicon AutoAnalyzer. The silicomolybdate formed is reduced to molybdenum blue with iron(II). Fluoride is added to provide a redox buffering system. The novelty of the method lies in selecting the sample sizes, conditions of fusion and/or dissolution and dilutions so that this universality is attained. Thus a single programme for the analyzer serves to determine, in any sequence, silicon in iron ores or sinters (1-6%), slags (3-10%), iron (0.4-2.5%) or steel (0.005-2%), the only change being in the tables used to translate transmittanee into per cent silicon. Both the precision and accuracy are satisfactory.     

Catalytic method for determination of micro amounts of gold in iron ores

Summary Gold in iron ores has been determined by means of its catalytic action on the oxidation of mercury(I) by cerium(IV). The calibration curve is linear over the range 3–30 ng/ml. Only iridium(IV), platinum(IV), palladium(II), ruthenium(III) and gallium(III) interfere seriously, though some interference is experienced from lead(II), iron(III), osmium(VIII) and indium(III).

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Zusammenfassung Gold wurde in Eisenerzen auf Grund seiner katalytischen Wirkung auf die Oxydation von Quecksilber(II) durch Cer(IV) bestimmt. Die Eichkurve verläuft von 2 bis 30 ng/ml linear. Nur Iridium(IV), Platin(IV), Palladium(II), Ruthenium(III) und Gallium(III) stören ernstlich, während eine geringfügige Störung auch durch Blei(II), Eisen(III), Osmium(VIII) und Indium(III) beobachtet wurde.

     

Rapid determination of traces of silver in sulphide ores by atomic absorption

The silver in sulphide ores is assayed by dissolution of the sample in aqua regia, addition of excess of ammonia solution and the measurement of the atomic absorbance of the supernatant solution at 328.1 nm.     

Rapid method for the photometric determination of manganese in ores and alloys

Summary A procedure for the rapid photometric determination of manganese in the range of 4–24 mg/50 ml, is based on the oxidation of manganese(II) to manganese(III) by excess potassium dichromate in a medium of 8.0 to 9.0 M phosphoric acid at room temperature. Interferences are few when compared to the methods currently available. The method can be successfully employed for the estimation of manganese in ores and alloys and the results obtained compare favourably with standard methods. The method is therefore recommended for adaption for rapid routine analysis.

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Schnelle Methode zur photometrischen Bestimmung von Mangan in Erzen und Legierungen

Zusammenfassung Ein Verfahren zur raschen Bestimmung von Mangan im Bereich von 4–24 mg/50 ml wird beschrieben. Es beruht auf der quantitativen Oxydation von Mn(II) zu Mn(III) mit Dichromat in 8,0–9,0 M phosphorsaurer Lösung bei Raumtemperatur. Die Störmöglichkeiten sind geringer als bei sonst üblichen Methoden. Das Verfahren wurde mit Erfolg zur Manganbestimmung in Erzen und Legierungen angewendet und gute Übereinstimmung mit Standardmethoden erzielt. Es wird für die schnelle Routineanalyse empfohlen.