GB448328A - Improvements in the electrolytic production of lead - Google Patents

Abstract

448,328. Electrolytic production of lead and sulphur. NATIONAL PROCESSES, Ltd., 95, Gresham Street, London, and GIBSON, A. R., 2, Oakland Road, Redland, and ROBSON, S., Penpole House, Shirehampton, both in Bristol. Nov. 5, 1934, No. 30845/33. [Class 41] Lead and sulphur vapour are obtained by electrolysis of fused lead chloride containing 1-10 per cent of lead sulphide added in the form of galena or other material, with a current density between 500 and 1,000 amps per sq. ft. As the sulphide concentration is increased within the specified limits, the current density must be correspondingly increased to maintain a constant flow of sulphur vapour from the neighbourhood of the anode ; otherwise normal electrolysis may be suspended owing to the formation of lead di- or polysulphide. By maintenance of the specified conditions formation of sulphur chloride is also avoided. For a sulphide concentration of 3-5 per cent a current-density of 750-1,000 amps per sq. ft. is suitable. A temperature of 500-600‹ C. is maintained. A column of bi-polar electrodes may be employed with a voltage of 1À2-1À4 per gap. The mixture may be subjected to preliminary electrolysis to remove metals electro-negative to lead, particularly silver. The galena may be added in a separate compartment in which the gangue formed is skimmed off ; the preliminary electrolysis may be effected in this compartment. The mixture may pass to the cell proper through a molten lead seal. Sulphur is collected by a reflux condenser and the lead produced is removed from the cell by a syphon. Lead chloride may be recovered from the gangue and returned to the cell.