RU2814364C1 - Method of extracting cerium (iv) ions - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention relates to methods of extracting cerium (IV) ions from solutions of technogenic and natural origin. Cerium (IV) ions are extracted from nitric acid solutions of natural and technogenic origin by extraction with a melt of a mixture of paraffin and tributyl phosphate, which is a low-melting mixture which hardens at the end of extraction. Extraction is carried out at temperature of 80 °C with intense stirring for 20 minutes at a ratio of the volume of the organic phase to the volume of the aqueous phase of 1:10.

EFFECT: invention provides higher efficiency of cerium (IV) extraction ions without using extraction mixtures containing toxic and flammable substances, as well as simplifying the process of separating the aqueous phase from the organic phase at the end of extraction.

1 cl, 1 dwg, 2 tbl, 2 ex

Description

The invention relates to extraction methods for extracting cerium (IV) from industrial waste; it can be used in the processing of cerium-containing ores or industrial waste containing cerium.

There is a known method for extracting cerium [Pat. 2530081] by extraction method with a solution of 2-methyl-8,9-dihydro[1,2,4]triazolo[1,5-α]quinazolin-6(7H)-one in methylene chloride from sulfate media, with the degree of extraction reaching almost 90 % (with phase contact time - 15 minutes).

There is also a known method for extracting cerium [Pat. 2441087] with an extraction mixture consisting of oleic acid and kerosene with a ratio of the volume of the organic phase to the volume of the aqueous phase (O:W) of 1:10 in two stages. The disadvantage of this method is its multi-stage nature, as well as the use of flammable kerosene as an extractant diluent.

A similar method for extracting cerium [Pat. 2320738] is based on the use of a solution of naphthenic acid in o -xylene as an extractant in the presence of potassium chloride in the original solution (up to a concentration of 0.2 mol/l), while the degree of cerium extraction reaches 80%. The disadvantage of the method is the low recovery coefficient and the use of o -xylene with a low flash point in the extraction technology.

A common disadvantage for the described methods is the use of toxic and flammable liquids as diluents.

The claimed invention is intended to expand the list of extraction mixtures used to extract cerium.

The technical result is increasing the efficiency of cerium (IV) extraction ions without the use of extraction mixtures containing toxic and flammable substances, as well as simplifying the process of separating the aqueous phase from the organic phase at the end of extraction.

This result is achieved by the fact that in the proposed method, a nitrate solution of cerium (IV) ions (HNO ₃ content 10%) is extracted with a mixture of paraffin and tributyl phosphate (TBP) at a temperature above 60°C with a volume ratio of O:B = 1:10.

For extraction, a mixture of paraffin + TBP is used in a ratio of 2:8 to 8:2, the residual concentration of cerium is not more than 1.5 mg/l.

Method for extracting cerium (IV) ions is carried out as follows: a solution acidified with nitric acid containing cerium (IV) ions is placed in a reactor (Fig. 1), heated by a jacket through which heated water circulates, a low-melting extraction mixture is added in the ratio O:B = 1:10. A mixture of P-2 grade paraffin and tributyl phosphate (TBP content from 20% to 80%) is used as an extractant. After the extractant has completely passed into the liquid phase (melting temperatures of extraction mixtures are indicated in Table 1), extraction is carried out with constant stirring for 20 minutes. At the end of extraction, the temperature of the water in the jacket decreases, the solution after extraction is separated by draining after the solidification of the organic phase is complete. The cerium content is monitored by the photometric method with Arsenazo III. In fig. Figure 1 shows a diagram of a thermostatic reactor for extraction with a low-melting extractant based on paraffin and TBP

Table 1 - Melting temperatures of extraction mixtures Paraffin content P-2, wt. % TBP content, wt. % T _pl , °C 100 0 56.0 90 10 55.0 80 20 53.0 70 thirty 53.0 60 40 52.0 50 50 51.0 40 60 50.0 thirty 70 49.5 20 80 49.5 10 90 47.0

Execution example 1: A nitric acid solution containing cerium (IV) ions at a concentration of 140 mg/l and [NO ₃ ^- ]=2 mol/l is extracted with a low-melting mixture with a paraffin:TBP ratio (wt.%) 4:6, at a ratio of O :B=1:10 at 60°C for 20 minutes with vigorous stirring.

The method ensures the extraction of cerium with a degree of 98% to a residual concentration of Ce ⁴⁺ ions of less than 0.5 mg/l.

Execution example 2: A nitric acid solution containing cerium (IV) ions at a concentration of 100 mg/l and [NO ₃ ^- ]=2 mol/l is extracted with a low-melting mixture with a paraffin:TBP ratio (wt.%) 6:4, at a ratio of O :At 1:10 at 55°C for 20 minutes with vigorous stirring.

The method provides extraction of cerium with a degree of ~99% to a residual concentration of Ce ⁴⁺ ions of less than 0.3 mg/l.

Data on the degree of cerium extraction by the proposed method, depending on the ratio of components in the low-melting extractant, are given in Table 2.

Table 2 - Extraction results depending on the ratio of components in the extraction mixture Extractant composition, mass. % Water volume phases, Vaq., ml Extractant mass, mext., g Phase ratio (O:V) Distribution coefficient D Extraction rates R, % Paraffin TBP 100 0 20 2 1:10 36.3 78.4 90 10 20 2 1:10 74.1 88.1 80 20 20 2 1:10 82.7 89.2 70 thirty 20 2 1:10 102.7 91.1 60 40 20 2 1:10 915.4 98.9 50 50 20 2 1:10 175.0 94.6 40 60 20 2 1:10 170.5 94.5 thirty 70 20 2 1:10 144.2 93.5 20 80 20 2 1:10 920.4 98.9 10 90 20 2 1:10 144.2 93.5 0 100 20 2 1:10 19.8 66.5

From Table 2 it follows that the use of an extractant containing 60% TBP provides a high degree of extraction with low consumption of a low-melting extractant.

Claims (1)

A method for extracting cerium (IV) ions from nitric acid solutions of natural and man-made origin by extraction with a melt of a mixture of paraffin and tributyl phosphate, characterized in that the melt of a mixture of paraffin and tributyl phosphate is a low-melting mixture that solidifies at the end of extraction, and the extraction is carried out at a temperature of 80°C with vigorous stirring for 20 minutes at a ratio of the volume of the organic phase to the volume of the aqueous phase of 1:10.