Rapid chromite dissolution using a manganese dioxide-lithium sulphate-sulphuric acid mixture for matrix-independent determination of chromium

Chattopadhyay, Partha; Mistry, M.

doi:10.1016/0003-2670(94)80238-6

Cited by 7 publications

(3 citation statements)

References 16 publications

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“…When present in the refractory spinel mineral form of chromite (FeCr O ), it is highly resistant to acid attack [9]. Although the mineralogical forms of Cr have not been identified in the National Research Council of Canada (NRCC) Marine Sediment Reference Materials BCSS-1 and MESS-1, our laboratory and others have consistently experienced problems with the full recovery of the certified contents of this element from these materials following their ''total'' dissolution [5,7,8,10], whereas complete recovery of this element from other reference materials, such as NIST SRM 2704 (Buffalo River Sediment), can be readily achieved [8].…”

Section: Introductionmentioning

confidence: 99%

Determination of total chromium in Marine Sediment Reference Material BCSS-1

Liu

Sturgeon

Boyko

1996

Analytical and Bioanalytical Chemistry

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The determination of Cr in National Research Council of Canada Marine Sediment Reference Material BCSS-1 is addressed. Mixed acid digestions utilizing HF, HClO(4) and HNO(3) were investigated. Single microwave assisted digestions in closed vessels at medium pressures (8 bar) were inappropriate (80% recovery). Double digestion at moderate pressure and digestions at high pressure (70 bar) or lengthy open-beaker hot plate dissolutions resulted in 93+/-5% recovery of certified Cr content. Flame atomic absorption and inductively coupled plasma atomic emission spectrometry were used for quantitation. In all cases, the method of standard additions was necessary to eliminate the approximately 10% enhancement in re- sponce relative to unmatched standards. Compared to a certified content of 123+/-7 microg/g (mean and standard deviation), values of 116+/-6 were obtained using an open beaker digestion; 114+/-5 using a double microwave digestion at 8 bar; 113+/-2 for microwave digestion at high pressure and 111+/-4 at high pressure (81 bar) with triple microwave digestion in a Parr bomb. No acid dissolution procedure is adequate for Cr in this sample although recovery of total Cr is complete from National Institute of Standards and Technology Buffalo River Sediment (SRM 2704).

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Section: Introductionmentioning

confidence: 99%

Determination of total chromium in Marine Sediment Reference Material BCSS-1

Liu

Sturgeon

Boyko

1996

Analytical and Bioanalytical Chemistry

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“…To ensure complete oxidation of chromium to hexavalent state, take an aliquot of 50 mL from the above solution. Add 20mL of aqueous solution peroxodisulphate (10%, w/v) and 5 mL of AgNO 3 solution (1% w/v) [1]. Precipitate (twice) R20 3 (the so-called R20 3 group of elements, comprising Fe20 3, AlzO3, TiO z and P205, is precipitated as hydroxides when an acidic solution from which silica has been removed is neutralized with ammonia E11]) with NH4OH NH4C1.…”

Section: Chemicalsmentioning

confidence: 99%

“…The proper dissolution procedure is one which yields no residue or precipitate. In our earlier communication [1], a procedure for rapid analysis of chromium in chromite samples has been described. In a continuation of the previous work, the present communication deals with the determination of alumina in chromite samples for quality control requirement.…”

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confidence: 99%

Rapid chromite dissolution using manganese dioxide-lithium-sulphate-sulphuric acid mixture-estimation of alumina in chromite for quality control assessment

Chattopadhyay

Mistry

1996

Mikrochim Acta

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Abstract. Proposed in this paper is a less labour-intensive method involving a mixture (0.3 g MnO 2 + 1.0 g Li2SO~; + 10 mL H20 + 20 mL of 36 M H2SO 4 for 0.2 g sample) to decompose chromites for accurate and precise estimation of alumina in chromite matrices for quality control (QC) assessment. Several international chromite samples, namely, CHR-BKg, CHR-Pt, IGS-30 and BCS-308 were analysed. Intermethod comparison studies reveal that the probability of results being different is less than (slight variation in case of CHR-BKg) 99 % when two methods l-ethylenediamine tetraacetic acid (EDTA) titration and spectrophotometry using ammonium aurinitricarboxylate (aluminon)] were compared. It also shows that the proposed method yields better results than the most conventional route involving HCIO 4 decomposition used for similar purpose; hence can be used for QC programme and in the evaluation of reference materials.Key words: chromite dissolution, MnO2-H2SO4-Li2SO 4 mixture, alumina estimation, quality control.Chromite or chrome ore is the sole commercial source of chromium metal, its alloys and compounds. It is also the major ingredients of an entire group of refractories. The mineral chromite is a spinel with the theoretical formula FeCr20r and the general formula (Fe +2, Mg) (Cr, A1, Fe + 3)20 4. There are wide variation in the composition of chromite because of this isomorphous replacement. The commercial ore is normally admixed with small amount of gangue which is principally a magnesium silicate. Commercial ores fall into three major classes: metallurgical ores, having chromic oxide content of 48%, a Cr/Fe ratio in the excess of 3 and A1/Mg ratio over 1; refractory ores, in which the Cr20 3 content is usually about 30-35%,

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Quantitative analysis of chromite ores using glass discs in moderate dilutions of lithium tetraborate by x‐ray fluorescence spectrometry

Ramos

Cubillos²,

Gimeno-Adelantado

et al. 2006

X-Ray Spectrometry

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A method for the quantitative analysis of chromite ores by x-ray fluorescence spectrometry using beads is proposed. The work concerned the serious problems caused by the refractory nature of these materials which prevents the use of glass discs in x-ray fluorescence. An in-depth study was done to optimise the variables which influence the glass disc formation process. Sufficiently homogeneous glass discs were obtained under the following experimental conditions: lithium tetraborate as flux with moderate sample dilution (1 : 40), with the addition of one or two drops of LiBr solution(250 g l −1 ), at a temperature of 1200°C for 30 min. The qualitative and semiquantitative results for the chromite ores provided synthetic standards based on combinations of similar reference materials and different pure ignited oxides. These standards were used to obtain the calibration curves for Cr, Si, Al, Fe, Ti, Ca, Mn, Mg, Na and K oxides, with root mean square error always below 0.357. The calibration curves were used in the quantitative analysis of chromite ores with satisfactory accuracy, justifying compensation of the interelemental effects. The suggested method is an efficient solution to the problems with the quantitative analysis of this type of material by XRF.

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Rapid chromite dissolution using a manganese dioxide-lithium sulphate-sulphuric acid mixture for matrix-independent determination of chromium

Cited by 7 publications

References 16 publications

Determination of total chromium in Marine Sediment Reference Material BCSS-1

Determination of total chromium in Marine Sediment Reference Material BCSS-1

Rapid chromite dissolution using manganese dioxide-lithium-sulphate-sulphuric acid mixture-estimation of alumina in chromite for quality control assessment

Quantitative analysis of chromite ores using glass discs in moderate dilutions of lithium tetraborate by x‐ray fluorescence spectrometry

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