GB/T 16484.1-2009Chemical analysis methods for rare earth chloride and light rare earth carbonate - Part 1: Determination of the cerium oxide content - Ammonium ferrous sulfate titrimetry (English PDF)

GB/T 16484.1-2009 is the English-translated version of 氯化稀土、碳酸轻稀土化学分析方法 第1部分：氧化铈量的测定 硫酸亚铁铵滴定法.

China's national method for determining how much cerium a rare earth chloride or a light rare earth carbonate contains, by titration with ammonium ferrous sulfate.

It is Part 1 of GB/T 16484 and specifies the determination of the cerium oxide content in rare earth chloride and light rare earth carbonate.

Rare earth chloride and light rare earth carbonate are the bulk intermediates through which the light rare earths move from the mine to the separation plant, and cerium is by far the largest component of both - roughly half of the rare earth content of the common Chinese ores is cerium.

So the cerium figure is what the tonnage is priced against, and it also decides the feed composition for the separation circuit that follows. The method exploits the one property that separates cerium from every other rare earth: cerium alone has an accessible tetravalent state.

All the other rare earths in the sample are locked in the trivalent form and cannot be titrated, but cerium can be oxidised to cerium(IV) and then titrated back to cerium(III) with a standard solution of ammonium ferrous sulfate, with a redox indicator marking the end point.

Nothing else in the matrix responds, which is what makes a simple volumetric method accurate in a sample containing fourteen chemically similar elements.

What the standard has to fix is the dissolution, the oxidation step and its completeness, the removal or masking of the few interferences that do respond - iron above all, since the titrant is itself an iron salt - the titre standardisation, and the tolerances on the result.

Issued on 30 October 2009 and in force since 1 May 2010, it replaces GB/T 16484.1-1996.

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This preview omits tables, figures, formulas and parts of the technical clauses. The complete document — 15 pages — is available in the English PDF.

GB/T 16484.1-1996|GB/T 16484|GB/T 14635-2008|GB/T 16479-2020|GB/T 12690|GB/T 18115

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