GB190212691A - An Improved Process for the Electrolytic Decomposition of Alkaline Chlorides and Apparatus therefor. - Google Patents

Abstract

12,691. CuÚnod, H., and Fournier, C. June 3. Chlorine; hydrogen.- Sodium chloride or other alkaline chloride solution is electrolysed in a cell divided by two porous partitions into three closed compartments. The middle compartment is packed loosely with pumice which has been saturated with cobalt nitrate and then made incandescent ; or any suitable metallic peroxide may be placed in it. The solution in the middle compartment is kept hot. The other compartments respectively contain the anodes and cathodes. The relative hydraulic pressures in the three compartments are made such as to limit mixing through the partitions, except that free chlorine and caustic soda pass through them to the middle compartment in such proportions as to produce sodium chloride and oxygen only, under the influence of the peroxide. For this purpose, the hydraulic pressure in the middle compartment may be equal to that in the anode compartment, and greater than that in the cathode compartment. The cathode compartment may also be divided by horizontal partitions ; chloride solution is fed above the uppermost partition, and descends as it accumulates alkali, the hydraulic pressure being diminished below the partitions, where the pressure in the middle compartment is greater, in order to diminish the amount of caustic soda passing through the lower portion of the porous partition from the cathode compartment. This portion of the porous partition is also made thicker than its upper part. A suitable construction of the cell is shown. Cast-iron cylinders k, connected together and to a cast-metal base by bolts, and made tight with a mixture of tar and Portland cement, form the outer cell and cathodes. The porous partitions are formed by piled rings of asbestos, compressed between slate discs u. Small vertical holes m, extending through all the rings and the discs u, are connected together by channels in the base and in a slate top, and serve as the middle compartment ; the lower rings are of greater radius outside the holes m than the upper ones. The spaces between the asbestos rings and the iron cylinders k are the cathode compartments, which are divided by the slate discs u and are provided with pipes as shown to pass the solution downward. The central space in the rings and discs contains a hollow carbon anode t, carried by a lead cap. Hot solution is supplied from an elevated tank to the holes m at the bottom, and passes out at the top to supply the upper cathode compartment, and to circulate through a heater. Solution drawn from the top of the anode compartment may be passed through salt, and then raised to an elevated tank, from which it returns to the bottom of the anode compartment.