SU1436029A1 - Method of atomic-absorption analysis of molybdenium in presence of tungsten - Google Patents

Abstract

The invention relates to analytical chemistry and can be used in enterprises producing or using tungsten concentrates. The goal is to show the correctness of the analysis when determining molybdenum in the presence of tungsten. The method includes acid decomposition of the sample, the introduction of sodium hydroxide, phosphoric acid and aluminum in the ratio (B: 10) :( 30-45): 1 at their concentrations (1, 6-2, 0): (6, 1-9 , 0) and (0.18-- 0.22) wt.%, Respectively, and the determination of molybdenum by the atomic absorption method in gshameni dinitroxide-acetylene. As a result, the method is greatly simplified and significantly reduces -1 from its duration. 2 tab.

Description

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about about

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This invention relates to analytical chemistry and can be used in the analysis of materials containing tungsten, such as tungsten and scheelite catdrafts.

The purpose of the invention is to improve the accuracy of the analysis of materials by improving the selectivity and reducing the labor intensity.

This goal is achieved in that according to the atomic-absolute method for the determination of molybdenum, including the acid opening of the sample to be re-placed in solution, followed by the introduction of a spectroscopic buffer consisting of phosphoric acid and aluminum J mass ratio of phosphoric acid and aluminum 8 10; 30-45g1 with its content of 1.6-2.0 wt.%.

When using the proposed method, the correctness of the determination of molybdenum in materials containing tungsten,

In tab. 1 shows the definition of molybdenum in tungsten concentrates.

As a result of the cited research

It has been established that for the quantitative transfer of molybdenum to the solution in the analysis of tungsten concentrates, it is necessary, after acid decomposition, to add sodium hydroxide in the indicated ratio to phosphoric acid and aluminum at the indicated concentrations in the indicated concentrations. when tungsten acid is added, the NaOH transforms into the more active white form, and the phosphoric acid goes into the tungsten solution, linking it to a heteropolyacid.

Table 2 shows the results of studies on the cooling of the optimal ratio of reagents for the conversion of molybdenum into solution and its determination by atomic absorption.

As follows from Table 2; the optimal extraction of molybdenum from the sample suspension into the solution takes place at a mass ratio of sodium hydroxide, phosphoric acid, aluminum 8-10s; 30-45: 1 at their concentration in the solution 1.6-2, 0: 6.1–9.0 and 0.18–0.22 masl with lower hydroxy0

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Yes, sodium does not completely transfer the molybdenum into the solution, with a higher one, the white form does not completely dissolve and the solution viscosity increases, which leads to a deterioration of its dispersion into the flame. With a lower amount of aluminum, a noticeable effect of the composition of the solution on the results of the analysis is observed; at a higher level, the reproducibility deteriorates due to an increase in the salt composition and its effect. At a lower content of phosphoric acid, the complete dissolution of tungstic acid does not occur, and the higher the viscosity of the solution increases.

Example To a sample of a tungsten-free concentrate of 0.25 g, 15 ml of a mixture of concentrated acids HCl: HNO: HCl 4 Islsl are poured, put on a heated plate and evaporated to the state of moist salts (not to dryness). 15-20 ml of water and 45 g of solid NaOH. After decomposition of the yellow tungstic acid, precipitated out of the alkali becomes white (sometimes brownish), the precipitate becomes more voluminous. The contents of the flask are mixed, 12.5 ml of concentrated orthophosphoric acid, 12.5 ml of AlClj solution containing 40 g / l A1 are introduced, and transferred to a 250 ml measuring flask, added to the water and mixed. After a short time, a clear solution is obtained which is acidic. The solution is stable for a long time.

The solution is analyzed by the method of atomic absorption in the flame of dinitroxide acetylene by standard methods. Comparison solutions for molybdenum contain the same amounts of orthophosphoric acid and aluminum chloride as analyzed.

Found molybdenum 2.4 wt.%. The emission spectral method with inductively coupled plasma was found to be 2.4 wt.%.

Claims (1)

Invention Formula The method of atomic absorption determination of molybdenum in the presence of tungsten, including the translation spectroscopic buffer of phosphoric acid and aluminum and atomic absorption determination of tungsten in solution, characterized in that, in order to improve the accuracy of the analysis by improving the test, the sample is subjected to acid decomposition followed by the introduction of sodium hydroxide into the solution during its content 1 , 6-2.0 wt.% And a mass ratio to phosphoric acid and aluminum 8-10: 30-45: 1. , T a b l and c a G The standard sample of scheelite concentrate No. 142, the passport value of molybdenum is 0.23%. Table 2 2.4 7,6 0.2 13: 38: 1 1.8 7,6 0.15 12: 50.6: 1 Continuation of table 2 Increase in solution viscosity and dispersion The effect of the composition of the solution is observed.