Novel method for measuring iron without mercury

Abstract

The invention relates to a novel method for measuring iron without mercury, which comprises the following steps of: decomposing a test sample through mixed acid of hydrochloric acid, sulfuric acid and phosphoric acid; taking neutral red and sodium diphenylaminesulfonate as indicators; measuring the iron through a SnCl2-TiCl3-K2Cr2O7 volumetric method; reducing Fe<3+> of phi Fe<3+> / Fe<2+>=+0.76V through tin bichloride with phi Sn<4+> / Sn<2+>=+0.16V; adding neutral red reagent when the solution is flavescent, i.e. the solution still contains a small amount of Fe<3+>; taking the color change of the neutral red as an indicator indicating that Fe<3+> is completely reduced to be Fe<2+> according to the principle that the neutral red is reduced to be colorless after the Fe<3+> is reduced completely, and the neutral red reagent is blue in the Fe<3+> solution; dropping titanium trichloride with phi Ti<4+> / Ti <3+>=+0.1V until blue is disappeared; removing excess titanium trichloride through oxidation by a 5.000g. L<-1> sodium diphenylaminesulfonate-potassium dichromate standard solution method; and finally, calculating ion grade of the test sample.

Description

technical field [0001] The invention relates to a technique for analyzing total iron in iron ore, in particular to a new method for measuring iron without mercury. Background technique [0002] The analysis of total iron in iron ore is generally to decompose the sample with concentrated hydrochloric acid (HCl) or mixed acid of sulfur and phosphorus, and use stannous dichloride-mercuric chloride-potassium dichromate (SnCl 2 -HgCl 2 -K 2 Cr 2 o 7 ) volumetric method to determine iron, this method has the advantages of accuracy and high precision, and has been widely used for many years at home and abroad, but due to the use of toxic mercury salts, it pollutes the environment and endangers human health, which has become a serious defect of this method; and hydrochloric acid It is difficult to decompose minerals such as ilmenite, chromite, wolframite, and sulfur-phosphorus mixed acid is difficult to decompose minerals such as pyrite and pyrrhotite; moreover, the separation p...

AI Technical Summary

Problems solved by technology

Gradually replaced by the mercury-free method of iron determination, the current method of mercury-free iron determination is useful TiCl 3 , SnCl 2 To reduce the iron in the ore, use silicon molybdenum yellow and methylene blue as indicator K 2 Cr 2 o 7 The volumetric method is used to determine iron, but there are still limitations of acid-decomposed samples, the indicator is expensive, the operation is troublesome, and the complicated process of secondary precipitation and secondary filtration is still required, so it is urgent to improve the existing method

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