铁矿石组份复杂,除铁、铝、钙、镁、锰、硅、磷外,常含有微量的铅、铜等元素。特别是包头铁矿,除上述元素外,还含有锶、钡、铌、锆、钛、氟及稀土元素。而且,磷的含量有时高达6％。欲以偶氮胂Ⅲ比色测定其中低含量稀土,大量的共存元素须加以细致地分离。铁矿石中低含量稀土的测定,往往用钙作载体氟化物沉淀或草酸沉淀进行分离。而引入的载体又必须作进一步的分离。有人虽提出了丙酮草酸沉淀法,但对组份复杂的样品 Iron ore complex components, in addition to iron, aluminum, calcium, magnesium, manganese, silicon, phosphorus, often containing trace amounts of lead, copper and other elements. In particular, Baotou iron ore, in addition to the above elements, but also contains strontium, barium, niobium, zirconium, titanium, fluorine and rare earth elements. Moreover, the phosphorus content sometimes up to 6%. To arsenazo Ⅲ colorimetric determination of low levels of rare earth, a large number of co-existence of elements to be carefully separated. Determination of low levels of rare earth iron ore, calcium fluoride carrier precipitation or oxalic acid precipitation are often used for separation. The introduction of the carrier must be further separated. Although some people have proposed acetone oxalate precipitation method, but the composition of the sample complex