GB183671A - Improvements in the process for the production of hypochlorites and chlorates and apparatus therefor - Google Patents

Abstract

183,671. Wilderman, M. June 16, 1921. Calcium and magnesium chlorates and hypochlorites; potassium chlorate.-- Relates to the manufacture of chlorates and hypochlorites, more particularly the former, of calcium or magnesium by chlorination of the corresponding hydroxide, and to the preparation of potassium chlorate, therefrom. A dilute suspension of calcium or magnesium hydroxide is chlorinated, to which fresh material is added from time to time, until a solution of chlorinated products of 60-64‹ Tw. is obtained. For example, milk of lime containing about 50 grs. Ca (OH)2 in suspension is prepared in the mixer c, agitated by the stirrer m, and, the valves r<1>, s<1> being closed, is pumped by pump p to the top of the towers a, a<1> through which it descends into the vessel b. A distributing-plate h, together with ebonite-coated glass balls i, serves to distribute the liquor, and expose a very large surface to the action of the chlorine, while at the same time preventing the deposition of solid matter in the towers. Chlorine, of a suitable concentration, passes through the towers, entering at e, e<1> and leaving at f, f<1>, as shown. The liquid in the vessel b is agitated by the stirrer j, and returns by the siphon k into the mixer c. Thence it is again circulated through the towers. As the chlorination proceeds, fresh lime is periodically introduced into the mixer c, through the inlet n. The temperature during chlorination is kept below 70‹ C., by using diluted chlorine, and, if necessary, by adding water to the liquor in the mixer c. The product of the process, a solution of calcium chlorate and chloride, and possibly hypochloride, of 60 -64‹ Tw., is pumped from the mixer and filtered. If it is desired to prepare potassium chlorate, potassium chloride, in an excess of 2 per cent over the theoretical amount, is added and the bulk of the chlorate allowed to crystallize at atmospheric temperature. The mother liquor is diluted, if necessary, until there is present preferably 45-50 grs. calcium chloride in 100 grs. of water, when the liquor may be cooled to -20‹ C. to separate further quantities of potassium chlorate, without simultaneous separation of ice or of calcium chloride. It is convenient to connect the outlet f<1> of the apparatus to a similar apparatus in which comparatively fresh milk of lime is being treated. Then when the liquor circulating in the first unit has been completely chlorinated, the valves r, s are closed, and the partly chlorinated lime in the second unit is pumped into the mixer c<1> for treatment as described above. Preferably, however, the conveyance of liquor is avoided by reversing the order of the units, and conducting the chlorine first to the second unit and then to the first unit, the mixer c<1> of which contains fresh milk of lime. The chlorine mains are provided with connections (not shown) to enable this to be done. The process may be applied to the production of concentrated hypochlorite solutions. Specifications 20068/96. 18269/08, [Class 70, India-rubber &c.]. also 12424/09 are referred to.