SU602611A1 - Method of extracting heavy non-ferrous metals by electrolysis - Google Patents

Description

(54) METHOD FOR EXTRACTING HEAVY

COLOR METALS ELECTROLYSIS

This invention relates to metallurgy, in particular, to the electrolytic extraction of metals from aqueous solutions of their salts.

The known method of extracting heavy non-ferrous metals by electrolysis of aqueous solutions of their salts using direct current and applying a pulsed current on it with an amplitude greater than the value of direct current 1. The known method involves the imposition of unipolar pulses with an amplitude exceeding five times the constant Nnnogo current, the interval between pulses 1 - 50 s.

The disadvantages of this method are

insufficient efficiency of electrolysis, due to the inability to increase the current density, as well as poor quality of sediment.

In order to improve the quality of the sludge and the efficiency of electrolysis, a pulsed current with opposite-polarity pulses with a duration of 1–20 ms and intervals between them is used, not exceeding 5 ms.

To extract metals with an electrode potential that is more negative than that of hydrogen, first a reverse pulse is applied, and then a forward pulse. For metals with an electrode potential that is more positive than that of hydrogen, first a direct, and then an upper pulse is applied.

The method of extraction of heavy non-ferrous metals from solutions of their salts is carried out as follows.

A constant current from the main source is supplied to the electrolytic cell with anodes and cathodes filled with electrolyte. This current is operational. A pair of opposite-polarity impulses from an auxiliary current source is imposed on it at the times specified by the control device.

FIG. Figures 1 and 2 show the electrolysis current curves using the present invention, with FIG. 1 reflects the change in current over time during the electrolysis of metals more electronegative than hydrogen, and FIG. 2 - more electropositive.

The multiplicity of pulses in relation to the DC power is 2-8, the intervals between the pairs of pulses are 0.2-2 s. Example 1. Nickel is refined in a standard sulfate-chloride electrolyte of the following composition, g / l: 65-75 Ni, 40-60

Nad 60 NajSO4, 3-8 Hz. The catholyte pH is 2-3, circulating 10-15 liters per 1 kg of increased nickel at 60-80 ° C.

First, follow the negative polarity pulses (cf. Fig. 1) with a multiplicity of 4-8, duration from 2-5 ms (at the beginning of the process) to

15–20 ms, then forward of the same multiplicity. Increasing the duration of the reverse pulse contributes to the stabilization of the pH value, which has a tendency to increase during the process. A change in the duration of the direct pulse has the opposite effect. A working current density of 2000 A / m2 was achieved with high quality sludge and low sludge formation.

Example 2. Electrorefining of copper is carried out in a standard electrolyte of the following composition, g / l: 37-43 Cu, 150-200, 28-35 C, circulation 5-18 l / min, temperature 50-60 ° C. First, pulses of positive polarity follow, then negative (see Fig. 2). The multiplicity of pulses in relation to direct current is 4–8, the duration is 5–20 ms, the intervals between them are 0.5–2 s. Achieved a working current density of 2000 A / m with high quality sediment.

With the usual DC electrolysis technology, an increase in current density above 500-800 A / m is impossible because of the passivation of the anodes and the formation of sludge at the cathode.

Claims (3)

1. A method for extracting heavy non-ferrous metals by electrolysis of aqueous solutions of their salts using direct current and applying a pulsed current to it with an amplitude greater than the direct current value, characterized in that, in order to improve the quality of the precipitate and the efficiency of the process, A pulsed current with opposite-polarity pulses with a duration of 1–20 ms and an interval between them not exceeding 5 ms is used. 2. A method according to claim 1, characterized in that, in order to extract metals with an electrode potential more negative than that of hydrogen, first, a reverse pulse is applied, then a direct one. 3. A method according to claim 1, characterized in that, in order to extract metals with an electrode potential more positive than that of hydrogen, first a direct pulse is applied, and then a reverse pulse is applied. Sources of information taken into account in the examination: 1.. USSR author's certificate number 398700, cl. C 25 D 5/18, 1971.