RU2257426C1 - Zirconium production process - Google Patents

Abstract

FIELD: production of refractory metals, namely zirconium by electrolysis of melt salts.

SUBSTANCE: process comprises steps of electrolysis of melt of fluoride-chloride electrolyte containing, mass %: zirconium, 3 - 5, chlorine, 8 - 13; sodium, 2 - 4; cyclically charging to melt potassium fluozirconate, potassium chloride and sodium chloride for sustaining predetermined content of electrolyte; further separation of zirconium powder by hydraulic metallurgy; performing electrolysis at adding to melt magnesium chloride additive in quantity providing mass content of magnesium in electrolyte 0.05 - 0.5%.

EFFECT: improved current yield of zirconium powder at electrolysis, extraction of zirconium from initial salt to powder, lowered specific consumption of DC power.

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Description

The invention relates to the field of production of refractory metals, in particular zirconium, by electrolysis of molten salts.

Closest to the claimed technical solution (prototype) is a method for producing zirconium by electrolysis of a molten fluoride-chloride electrolyte containing potassium fluoride, potassium chloride and potassium fluorozirconate, according to which the increase of technical and economic indicators (increase in cathodic current efficiency and extraction of zirconium from potassium fluorozirconate to powder) is achieved by introducing sodium chloride into the melt while maintaining the mass fraction of zirconium in the melt 3-5%, chlorine - 8-13%, sodium - 2-4% (A. S. USSR, No. 1776092, class C 25 C 3 / 26).

The disadvantage of this method is that an increase in the mass fraction of sodium by more than 4% leads to a decrease in technical and economic indicators due to the formation of slightly soluble fluoride compounds of sodium and zirconium in water, which complicate the separation of the salt phase during the hydrometallurgical treatment of the cathode deposit.

The invention solves the problem of increasing the technical and economic indicators of electrolysis. The technical result is to increase the current output of zirconium powder and to extract zirconium from the initial salt to the powder, to reduce the specific consumption of direct current electricity.

The technical result is achieved by the method of producing zirconium, including electrolysis of a fluoride-chloride electrolyte melt with a mass fraction of zirconium 3-5%, chlorine 8-13% and sodium 2-4%, periodic loading of potassium fluorozirconate, potassium chloride and sodium chloride salts into the melt to maintain the specified composition of the electrolyte and the subsequent separation of the zirconium powder by the hydrometallurgical method, according to the invention, the electrolysis is carried out with the introduction of a magnesium chloride salt in the melt in an amount that ensures the maintenance of mass whether magnesium in the electrolyte is 0.05-0.5%.

The possibility of implementing the proposed method is confirmed by the following experiments.

Example

The electrolysis was carried out in an industrial sealed electrolyzer with a current load of 10 kA from a melt containing potassium fluoride, potassium chloride, potassium fluorozirconate and sodium chloride. During the electrolysis of the prototype, the specified melt composition was maintained according to the current technological regulations by periodically loading potassium chloride, potassium fluorozirconate and sodium chloride, and during electrolysis according to the proposed method, magnesium chloride was additionally introduced into the melt. The mass fraction in the melt during the experiments was:

- the prototype: zirconium 3-5%, chlorine 8-13%, sodium 2-4%;

- by the proposed method:

- zirconium 3-5%, chlorine 8-13%, sodium 2-4%, magnesium less than 0.05%;

- zirconium 3-5%, chlorine 8-13%, sodium 2-4%, magnesium 0.05-0.5%;

- zirconium 3-5%, chlorine 8-13%, sodium 2-4%, magnesium more than 0.5%.

The cathode deposit obtained by electrolysis of a melt with close values of the mass fraction of magnesium was completed in a batch and subjected to hydrometallurgical treatment in accordance with the current technological regulations. The values of the mass fraction of melt components averaged over each experiment, the current output of zirconium, the extraction of zirconium from potassium fluorozirconate to powder, and the specific direct current power consumption are shown in Table 1.

From the data given in table 1, it is seen that the highest current output of zirconium and the extraction of zirconium from potassium fluorozirconate to powder, as well as the smallest specific direct current power consumption were achieved with a mass fraction of magnesium in the melt of 0.05-0.5%. When the mass fraction of magnesium is less than 0.05%, the technical and economic indicators of electrolysis practically do not differ from the prototype. With an increase in the mass fraction of magnesium of more than 0.5%, a decrease in current efficiency and extraction of zirconium from potassium fluorozirconate to a powder is observed.

The proposed method was tested in the process of pilot testing and is recommended for implementation in the current technological scheme for the production of electrolytic zirconium powder.

Claims (1)

A method of producing zirconium, including electrolysis of a molten fluoride-chloride electrolyte with a mass fraction of zirconium 3-5%, chlorine 8-13% and sodium 2-4%, periodic loading of potassium fluorozirconate, potassium chloride and sodium chloride into the melt to maintain a given electrolyte composition and subsequent separation of the zirconium powder by the hydrometallurgical method, characterized in that the electrolysis is carried out with the addition of magnesium chloride salt in the melt in an amount that ensures the maintenance of the mass fraction of magnesium in the electrolyte 0.05-0.5%.