RU2343231C1 - Facility for continuous electroextraction from solutions of metals' salts - Google Patents

Abstract

FIELD: metallurgy.

SUBSTANCE: invention concerns facilities for continuous electroextraction of metals from solutions of its salts. Facility contains, at least, two electrolyte pots with initial solution, connected to each other by common electrode moving through them by means of propelling roll, feed bar made of graphitic rolling press and counter electrodes. Common electrode is implemented in the form of closed annulus, containing of graphitized conducting sections and sections made from nonconducting chemical-resistant fabric. Common electrode is installed with ability of simultaneous extraction of target metal from initial solution and its extraction in final electrolyte pot on accumulation electrode.

EFFECT: facility design simplification at implementation of continuous electroextraction of metals, operation life increasing of electrode without destruction in hostile chemical environment.

8 cl, 5 dwg, 2 ex

Description

The invention relates to electrochemistry and is intended for electrochemical extraction of metals from solutions of their salts.

Such metals include, for example, copper, silver, gold, platinoids, rare metals.

Known devices, including the chambers of electrolytic cells with electrodes made of carbon-graphite materials, for the extraction of metals, for example, noble metals (US Pat. RU 2021394 C1, C25C 7/00, 10/15/1994), with electrodes made of graphite batting (US Pat. RU 2248413 C2, C25C 7 / 02, March 20, 2005); an electrolyzer for electrochemical extraction of metal from an aqueous solution containing a cathode, which includes a deposition surface on which metal is deposited during electrolysis of an aqueous solution, and during operation of the electrolyzer, the deposition surface has an inhomogeneous electric field having sections of a strong electric field alternated with sections of a weak electric fields (application RU 2005115463 A, C25C 1 / 00,27.10.2005).

The closest analogue of the claimed invention is a device for the electrolytic extraction of metals from solutions of their salts, including an electrolyzer, the cathode chamber of which contains a housing with perforated walls, divided by perforated conductive partitions into three sections, carbon graphite electrodes placed in the outer sections and made in the form of a tape laid in sections zigzag (US Pat. RU 2054055 C1, C25C 7/02, 02/10/1996) - prototype.

A disadvantage of the known technical solution is its complexity and difficulty of operation, as well as the limited life of the electrode in it.

The technical result when using the claimed invention is to simplify the design of the installation during continuous electrochemical extraction of metals, increase the life of the electrode in stationary mode without destruction in aggressive chemical environments in one device with different electrical modes at the same time.

The specified technical result is achieved in that the installation for continuous electrochemical extraction of metals from solutions of their salts contains at least two electrolytic baths with the initial solution, interconnected by a common electrode moving through them using pulling rollers, current leads from graphite rollers and counter electrodes, wherein the common electrode is made of graphitized conductive carbon tape connected in a closed ring, contains sections of conductive chemically resistant fabric and installed with the possibility of simultaneous extraction of the target metal from the initial solution and its allocation in the final electrolytic bath on the storage electrode. The tape electrode is made in the form of a Mobius strip; polypropylene fabric is used as a non-conductive fabric; sections of polypropylene fabric are connected to the carbon tape by stitching; the storage electrode in the final electrolytic bath is made of carbon fabric or a plate of metal.

The installation may further comprise at least one washing bath with running water. The counter electrodes in the electrolytic baths, except the final one, are made of carbon graphitized material, and in the final electrolytic bath, they are made of carbon graphitized material or from a metal foil similar to the metal to be extracted.

The installation is configured to selectively extract metals from solutions of their salts.

The invention is illustrated by drawings, where:

figure 1 shows the installation diagram, General view;

figure 2 shows a diagram of the electrode, a General view;

figure 3 shows the electrode in the form of a Mobius strip;

figure 4 shows a fragment of the electrode, including the connected sections of the carbon conductive tape and conductive tissue;

figure 5 shows the connection diagram of the sections of the electrode.

Installation for continuous electrochemical extraction of metals from solutions of their salts (figure 1) contains electrolytic baths 1, 2, 3, 4, interconnected by a common electrode 6 moving through them using pulling rollers 5, made of graphitized conductive carbon tape 7 (Fig. .2) in the form of a closed ring. The electrode 6 (figure 2, 5) contains sections 8 of a non-conductive chemically resistant fabric. The ends of the carbon tape are connected by turning 180 ° relative to each other (Fig. 3) in the form of a Moebius tape. Sections 8 (Figs. 4, 5) are made of polypropylene fabric and are connected to the carbon tape 7 by stitching, for example, with polyester thread 9. For fixing the carbon threads of the carbon tape, its electrical insulation and more durable adhesion, the ends of the tape are glued with fluoroplastic adhesive tape 10.

The distance n (figure 4) between the connected ends of the carbon tape 7, and, accordingly, the length of the portion 8 of the non-conductive fabric, is 0.5-1.0 cm, which is quite enough and necessary to interrupt the current between the electrode sections.

The initial solution containing the ions of the target metal is fed into an electrolytic bath 1 (Fig. 1), in which a carbon graphite tape 6 serves as a cathode, which with the extracted metal enters the bath 2, which is a wash with prepared running water; after exiting the bath 2, the electrode 6 is dried with hot air 11. To continue the process of extracting the metal from the solution, the carbon tape 6 is pulled through an electrolytic bath 3, in which the extracted metal is transferred from the carbon tape 6 to the cathode of the bath, and for subsequent washing, the carbon tape 6 they are pulled through the bath 4 with prepared running water and then, using the pulling rollers 5, it again enters the bath 1 with the initial solution. The electric current is supplied to the electrolytic baths through the upper graphite rollers 12 and counter electrodes 13, which in the electrolytic baths, except the final one, are made of carbon graphitized material, and in the final electrolytic bath, they are made of carbon graphite material or from metal foil. Recoverable metal in the final electrolytic bath is accumulated on cathodes made of carbon cloth or on metal plates made in the form of cassettes or rolls.

The electrochemical study of the initial solution, the reduction of the target metal ions in the electrolytic baths occurs in the galvanostatic mode at a load below the current limit for a given metal ion in this solution, which determines the selectivity of the process, and during the electrochemical dissolution of the target metal from the tape electrode and its transfer to the storage electrode in the final electrolytic bath flows in a specially selected solution for a particular metal in the galvanostatic mode at a current pre yshayuschem limiting current for a given metal ion in the solution. When working under these conditions, different sections of the electrode are at different current loads of different polarity, and in the spaces between electrolytic baths - without current.

The number of electrolytic baths, the length, width and speed of drawing a carbon tape (electrode) determine the selectivity, the degree of extraction of the target metal and the performance of the installation.

The process of extracting metals from their solutions is illustrated by examples.

Example 1

The initial solution contains cations of three metals: palladium 0.2 g / l, copper 0.5 g / l, iron 2 g / l. The electrode 6 is charged into the installation containing at least two electrolytic baths. A current is supplied to the first bath, the density of which during electroextraction of palladium is set lower than the value that could be set based on the concentration of extracted ions in this solution (limiting current). This can significantly increase the selectivity of extraction, but with a decrease in the degree of extraction of this ion, up to about 90%. After extraction of the target metal ions in the first bath, the depleted solution is sent with interruption of the jet into the second bath with a lower current value, in which approximately 90% more palladium is recovered.

The total recovery of palladium after the passage of the electrode through two electrolytic baths is about 99%. Thus, about 0.002 g / l palladium remains in solution.

Next, the electrode is pulled through the final electrolytic bath, in which palladium is electrochemically transferred to the storage electrode until a certain mass is accumulated on it.

Example 2

The initial solution of example 1 is fed into the installation, increased by two baths. After extraction of palladium from the solution and its subsequent transfer to the storage electrode, like Example 1, the solution containing copper and iron cations is sent to the next electrolytic bath, in which the electrochemical extraction of 99% copper takes place. Then the electrode is pulled through the bath, in which copper is electrochemically transferred to the storage cathode.

About 0.002 g / l palladium, 0.005 g / l copper and the initial amount of iron remain in the spent solution.

The claimed invention has several advantages in comparison with the prior art:

- ultimate simplicity of design and operation;

- by means of a common movable electrode and a multi-stage electrochemical process of metal extraction, selective, degree-controlled, extraction of the target metal is possible;

- a high percentage of metal recovery;

- all electrochemical processes proceed in a stationary mode;

- possible automation of the metal extraction process;

- when the electrode is executed in the form of a Moebius strip, the entire surface of the electrode works under the same conditions, the wear of the electrode occurs evenly and its service life increases.

Claims (8)

1. Installation for continuous electrochemical extraction of metals from solutions of their salts, containing at least two electrolytic baths with the initial solution, interconnected by a common electrode moving through them using pulling rollers, current leads from graphite rollers and counter electrodes, with a common electrode made in the form of a closed ring, consisting of graphitized conductive sections and sections of conductive chemically resistant fabric, and installed with the possibility of simultaneous extraction of intact metal from the initial solution and its allocation in the final electrolytic bath on the storage electrode. 2. The installation according to claim 1, in which the graphitized conductive sections and sections of conductive chemically resistant fabric connected in a closed ring form a Mobius strip. 3. The installation according to claim 1, in which polypropylene fabric is used as a non-conductive fabric. 4. The installation according to claim 1 or 3, in which sections of polypropylene fabric are connected to graphitized conductive sections by stitching. 5. The apparatus of claim 1, wherein the storage electrode in the final electrolytic bath is made of carbon fabric or a metal plate. 6. Installation according to claim 1, which further comprises at least one washing bath with running water. 7. The installation according to claim 1, in which the counter electrodes in the electrolytic baths, in addition to the final one, are made of carbon graphitized material, and in the final electrolytic bath is made of carbon graphitized material or from a metal foil. 8. The apparatus of claim 1, which is configured to selectively extract metals from solutions of their salts.

Images