SU1648899A1 - Method for purification of yellow phosphorus - Google Patents

Abstract

This invention relates to the technology of purification of yellow phosphorus obtained by the electrothermal method. The purpose of the invention is to reduce the processing time and ensure safe working conditions without reducing the product yield. The method involves treating the phosphorus with an aqueous solution of a ferric salt at a mass ratio of Fe AS. equal to 40-80, at 55-85 ° C for 3-5 hours and stirring at a speed of 30-90 rpm. 1 hp ff, 1 tab.

Description

This invention relates to a process for the purification of yellow phosphorus obtained by the electrothermal method.

The purpose of the invention is to reduce the processing time and ensure safe working conditions without reducing the product yield.

Example. 20.3 g of a 10% solution of iron trichloride are placed near a heat-resistant glass and the volume of the solution is brought to 100 mm. There placed 51.28 g of phosphorus containing, in wt.%:

mouse 0.023; organic compounds 0.167; insoluble residue 0.24. A glass with phosphorus and a solution of iron trichloride is placed in a water bath, heated to 70 ° C and maintained for 4 hours with stirring at a speed of 60 rpm. Mass ratio: As in the mixture is 60, Phosphorus is separated.

50.2544 g of phosphorus is obtained, which makes up 98% of the initial one with the following content of impurities, May%. mouse 0.003, organic compounds 0.005, insoluble residue 0.07.

PRI mme R 2. 62.8 g of a 5% aqueous solution of ferrous sulfate (Fe content + 3 0.88 g) are placed in a heat-resistant beaker and the volume of the solution is adjusted to 100 mm. There are placed 48,3113 g of phosphorus of the same composition as in example 1.

The process is carried out with the following parameters, the stirring speed is 90 rpm, the stirring time is 5 hours, the temperature is 85 ° C. 46.862 g of phosphorus or 97.1% of the original containing are obtained, wt%: mouse to 0.003, organic compounds 0.005, insoluble residue 0.06.

According to a known solution, a mixture of nitric and sulfuric acids with a total mole ratio of 3.5-6.5 M is used as an inorganic reagent. The process is carried out for 22 hours at 45-100 ° C. The output of phosphorus does not exceed 70%.

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The table presents data on the yield and quality of the product, depending on the process parameters.

Analysis of the results presented in the table shows that when an aqueous solution containing ferric iron is used for phosphorus purification in an amount corresponding to the mass ratio Fe3 +: As Рmas below 40 (example 1), there is an insufficient effective decrease in the content of arsenic, organic and an insoluble residue, since under these conditions the probability of collisions of Fe + ions with impregnations of impurities is low and their oxidation is not sufficiently complete. An increase in the Pmas value above 80 (Example 5) also does not lead to the effective purification of phosphorus due to the occurrence of side reactions.

A decrease in the stirring rate below 30 rpm (Example 6) also leads to insufficiently effective purification of phosphorus from impurities due to insufficient dispersion of phosphorus occurring under these conditions, and insufficient contact of Fe ions with impregnations of impurities. An increase in the stirring rate above 90 rpm (example 10), allowed to keep the degree of purification of phosphorus from impurities at a sufficiently high level, leading to a decrease in the yield of phosphorus due to splashing of the aqueous phosphorus emulsion, leading to partial loss of phosphorus. a handicap as a result of its combustion in air, which is also of some danger to the experimenter.

Reducing the mixing time to less than 3 hours (Example 11) leads to an insufficiently high degree of purification of phosphorus from impurities due to insufficient time for the processes of their oxidation, and an increase in the mixing time more than 5 hours (Example 15), maintaining the degree of purification of phosphorus to a sufficiently high level, is accompanied by a decrease in the yield of phosphorus due to its oxidation with Fe ions.

A decrease in the phosphorus treatment temperature below 55 ° C (Example 16) also leads to insufficiently effective purification of phosphorus from impurities, since under these conditions the degree of phosphorus liquefaction is insufficient for the intensive interaction of impurities with Fe ions. At a phosphorus treatment temperature above 85 ° C (Example 20), significant

loss of phosphorus as a result of its evaporation without a noticeable increase in the cleaning efficiency.

In examples 21-23 presents data on processing in a known manner.

phosphorus of the same composition as proposed.

Thus, the proposed method allows the process of purification of phosphorus from impurities in a short time (the processing time is 3-5 hours),

carry out the process of purification of phosphorus in safe conditions;

and without reducing its output.

As a result of purification from phosphorus with a high content of arsenic, organic and insoluble residue, to obtain phosphorus, the impurity content of which meets the requirements imposed on the quality of phosphorus.

Claims (2)

1. Method of purification of yellow phosphorus from arsenic, organic compounds and insoluble residue, including its treatment with an aqueous solution of inorganic reagent when heated and stirred and the separation of phosphorus, characterized in that, in order to reduce the processing time and ensure safe working conditions without reducing the product yield, as an inorganic reagent, a salt of ferric iron is used in an amount that provides the mass ratio of Fe +: As, equal to 40-80, and the process is carried out for 3-5 hours with a mixing rate of 30-90 rpm. 2. A method according to claim 1, characterized in that the process is carried out at 55-85 ° C.