Non-consumable anode for electrolysis

Abstract

The invention relates to a non-consumable anode for electrolysis that contains carbon. Said anode is made of pyrocarbon (pyrographite). The pyrocarbon (pyrographite) anode is stable even in nitrate electrolytes and does not contaminate the electrolyte with erosion products.

Claims

1. A carbon-containing nonconsumable anode for electrolysis, which is different in that it is made of pyrocarbon (pyrographite).

2. A non-consumable anode for electrolysis as per item 1, which is different in that the pyrocarbon is of UPA-3 grade.

Description

EMBODIMENTS OF THE INVENTION

[0010] Different samples of pyrocarbon (pyrographite) received in NIIGraphite were used for the production of the test anodes. The pyrocarbon anodes were tested in nitrate electrolyte in combination with the consumable anode made of silver purity level 99.99% in conditions of electrolytic process for the production of silver powder grade PSr1, intended for the production of electric contacts. Both anodes were connected to the positive pole of an electrolyser power source. The current supplied to the nonconsumable anode was 10÷15 times lower than that supplied to the consumable anode. The current density on the nonconsumable anode was maintained on the level of 10 A/dm.sup.2 within a period of several days. The electrolyte remained clear and clean. The production testing of the contacts made from the test powder PSr1 received with the use of the pyrocarbon (pyrographite) non-consumable anode, confirmed the high quality of the powder.

THE PREFERRED EMBODIMENT OF THE INVENTION

[0011] None of pyrocarbon samples contaminated the solution. However, it was noted that the pyrocarbon samples with a higher density demonstrated better stability compared to the samples with a lower density. The pyrocarbon grade UPA-3 (pyrolytic reinforced carbon) produced by the Novocherkassk electrode factory was chosen for the manufacturing of the industrial non-consumable anodes [13]. These anodes were put into operation in 2003 and are still successfully used in the electrolysis area of the silver powder production shop at one of the leading RF companies producing electric contacts. The anode erosion (0.12÷0.15% from deposited silver) is mainly of an electromechanical nature due to the fact that ‘interflake’ material bonds burn up under the effect of current and anions (OH.sup.− and NO.sub.3.sup.−)*, resulting in flakes' falling and being trapped by the anode filtration diaphragm without contaminating the solution. *-author version.

INDUSTRIAL APPLICABILITY OF THE ANODE

[0012] Many years of positive experience of the pyrocarbon (pyrographite) nonconsumable anodes' industrial use in the most corrosive nitrate electrolyte proving their extraordinary stability allow us to recommend such anodes for the use in those electrochemical production facilities where it is economically feasible. The raw material is not cheap but can compete with platinum metals in terms of price and quality, and with multilayer metal-oxide compounds in terms of usage conditions. Moreover, the use of such anodes will expand the possibilities for electrolysis development in nitrate media. And the pyrocarbon production growth will result in its lower cost, thus promoting its use in big electrochemistry.

CITATIONS

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