GB938093A - Electrol ytic cell for the preparation of lead with alkaline metals - Google Patents

Abstract

938,093. Electrolytic cells for producing leadalkali alloys. MONTECATINI SOC. GENERALE PER L'INDUSTRIA MINERARIA E CHIMICA. March 26, 1962 [March 29, 1961], No. 11494/62. Class 41. An electrolytic cell for the production of lead-alkali alloys, e.g. lead-sodium-potassium, by the electrolysis of molten alkaline chlorides in contact with molten lead as cathode wherein that internal part of said cell in contact with the lead alloy and the electrolyte is lined with magnesia refractory (2) and that part in contact with chlorine and electrolyte is lined with alumino-silicate refractory (3); the cell having a graphite anode (15) with a heated lead cathode flowing under the anode and in a circuit including a heat-exchanger (21). The cathodic alloy is circulated by a mechanical pump (20). Molten lead is supplied batchwise to the circuit from the electrically-heated melting pot (23), kept under nitrogen and connected with the pressurized side of the pump by pipe (24) which, at the instant of charging, is heated above the melting point of lead; alloy is discharged, also batehwise, into a tank (25) connected through pipe (26) to the pump inlet. The magnesia refractory contains about 90% MgO and the alumino-silicate material contains 30% Al 2 O 3 . Refractory insulation (4) separates the inner lining from the outer metal casing. Stainless steel pipe (6) is connected to the pressurized part of the circulation system. Pipe (8) used in conjunction with trap (7) is connected with the low pressure side of the circulation system, and with collecting tank (25) which is filled by gravity on heating pipe (26) above the melting point of the alloy and is kept under nitrogen. Molten salt electrolyte is fed through inlet (18) and comprises a mixture of 55% NaCl and 45% KCl to produce alloy of 89% Pb, 10% Na, 1% K. In an example, salt temperature is 710‹ C. and lead alloy temperature is 700‹ C., said alloy being 8 cms. deep at the start of electrolysis and increasing to 14 cms. with the feeding of 375 kgs. of molten lead and 111 kgs. of molten salt mixture. Current is at 1.7 A/cm.<SP>2</SP> at 5.5v for anodic surface of about 5,500 em.<SP>2</SP> and cathodic surface of about 11,000 cm.<SP>2</SP> and 55,000 amp.-hrs. are required. 410 kgs. of alloy yielding 43.5 kgs. of alkali metal were discharged with a current yield of about 92% and power consumption of 7 kwh. per kg. of metal produced.