GB714588A - Method of desulphurizing carbon-coated electrodes - Google Patents

Abstract

A method of desulphurizing a carbon-coated electrode comprises heating the electrode in an atmosphere of hydrogen mixed with a relatively large percentage of inert gas, the heat treatment being continued sufficiently long to ensure that substantially all of the sulphur is removed but not continued thereafter for a sufficient length of time to give rise to the formation of methane, whereby the desulphurization is effected with little or no loss of carbon from the electrode coating. The inert gas is nitrogen, helium or neon and the hydrogen comprises 5-10 per cent. by volume of the mixture. The mixture of hydrogen and inert gas is passed over the electrode heated in a furnace to a temperature of from 900 to 1100 DEG C. so that the electrode as well as being desulphurized is also outgassed. In an example a carbon-coated nickel electrode is desulphurized by passing a mixture of approximately 7 per cent. by volume of hydrogen over the electrode heated at atmospheric pressure in a tubular furnace, which can be of the type described in U.S.A. Specification 2,314,816, to a temperature of approximately 1000 DEG C. for a period of approximately 15 minutes. The rate of flow of the gaseous mixture is approximately one litre per minute per square inch of internal cross-sectional area of the furnace. After the heat treatment the electrode is moved to a cooling zone of the furnace where it is still subjected to the gaseous mixture and is subsequently removed from the furnace when it has cooled to room temperature.