SU678091A1 - Bipolar electrode - Google Patents

Description

I

The invention relates to the metallurgy of light metals, in particular to the production of magnesium by electrolysis from molten salts.

A bipolar electrode is known, in which a titanium base is coated on the anode side with a layer of noble metals or their oxides, with a cathode layer — a layer of carbon over which a layer of a metal such as iron, copper, chromium, cobalt, nickel or their alloys is applied.

The use of such bipolar electrodes for the electrolytic production of magnesium from melts and chlorides leads to a rapid dissolution of the anode part of the electrode and a decrease in the current output of magnesium due to the electroreduction of the metal of the anode part of the electrode at the cathode.

Bipolar electrodes for the electrolytic production of magnesium are known, in which the anode part is made of carbonaceous material and the cathode part is made of metal, for example iron 2.

The use of such bipolar electrodes under electrolysis conditions leads to carburization of the cathode part. It is known that with increasing carbon content in iron, its wettability by magnesium decreases, leading to a decrease in magnesium output by current.

The aim of the invention is to prevent passivation of the cathode part of the bipolar electrode by eliminating its carburization and increasing the current yield of magnesium.

The goal is achieved by the presence of an intermediate layer of another metal between the anode and cathode parts of the bipolar electrode, which prevents the diffusion of carbon from the anode part to the cathode one. The cheapest, most affordable and effective metal is copper.

The drawing shows a bipolar electrode.

Claims (2)

The electrode consists of carbonaceous material 1, electrolytic iron 2 and an intermediate layer of copper 3. Example. Bipolar electrodes were made: graphite - iron and graphite - copper - iron. Iron is coated with graphite in an electrolyte; ReCC.- - 455 g / l + NaCf - 60 g / l + - 5 g / l at a cathode current density of cGc - 0.2 a / cm and temperature C. The graphite was coated with copper by successive electrolysis in three electrolytes: 1. CuSO45Hj O - 2g /; N «4 1OO r / i 2.CuSO45HjO - 40g / l; Na4R„ О -15Og / - 90 g /; Z.Si5O45.N.O. -240g /; НjSO - 40g /. The duration of the electrolysis in the 1st electrolyte / C 2 min. at the current density, O2 in the 2nd apektroite С 35 min, cGc. Oh, 01a / cm and in the 3-m e ectrolit T-3.5 hours, OD a / cm. Copper coating thickness 0.5 mm. Then, the electrode was coated with iron in the aforementioned mode. Iron thickness 1 mm. The resulting electroshells were tested in a magnesium laboratory electrolyzer. The current yield of magnesium during the electrolysis of carnallite was 75% on the graphite iron electrode; on the electrode graphite copper - iron - 85-87%. Specific electric power consumption ССХ: graphite-iron electrode 14.1 kWh / kgM; for the electrode, graphite copper - iron - 12.3 kWh / kgMd; The use of other metals for the intermediate layer instead of copper (tungsten, niobium, titanium) showed that the current output of magnesium was lower than that of the electrode graphite copper-iron. Bipolar electrode for a magnesium electrolytic cell containing an anode portion of carbonaceous material and a cathode electrode of the same, characterized in that, in order to increase the current yield of magnesium by eliminating passivation of the cathode portion, an intermediate layer is placed between the cathode and anode parts. : fmaiii taken into account in the examination. 1. US patent hfe 3824175 ,, class. 204-90, 1974. 2. USSR author's certificate No. 258612, class, C 25 C 3 / O4, 1968.