Patent GB-174653-A (GB)
Title: Manufacture of sodium compounds and by products
IPC: C01B17/64
Filed: 1920-11-10
Abstract: Hydrated sodium sulphide reduced to powder reacts with air or oxygen at ordinary temperatures in the presence of finely-divided active charcoal, to give a product containing chiefly caustic soda and sodium thiosulphate.  Charcoals sold under the Registered Trade Marks "Eponit" and "Norit" are very active, but fine anthracite coal, animal charcoal, and charcoal obtained by the low carbonization of wood, coconut-shell &c., after being activated by treatment with air or steam at low temperatures are also suitable. If air is employed the residual nitrogen may be collected as a by-product.  After the reaction, the resulting mixture is treated in one of the following ways.  (a) The solution obtained by extraction with water is filtered, concentrated and cooled when crystals of thiosulphate, and a mother liquor of caustic soda are obtained.  The charcoal after washing may be used again.  (b) The product is leached with alcohol to extract the caustic soda, and then with water to extract the thiosulphate.  (c) The solution obtained by lixiviation with water is treated in the cold with carbon dioxide to precipitate the bi-carbonate and leave a solution of thiosulphate ready for crystallization of the carbon dioxide is passed into the hot solution, a mixture of sodium carbonate and thiosulphate is obtained which is separated by fractional crystallization.  (d) The solution containing from 10 to 40 per cent of sodium compounds obtained by extraction with water is electrolyzed when a solution of caustic soda is obtained at the cathode and a dilute solution of sulphuric acid and a loose precipitate of sulphur are obtained at the anode.  In an example, sodium-sulphide crystals are ground and well mixed with an equal quantity of active charcoal, in an apparatus provided with a water-jacket to prevent the temperature exceeding 100-200 DEG  C. Steam is evolved and the reaction is allowed to proceed until lead acetate gives a white precipitate with the solution of the product. The latter is extracted with water and subjected to fractional crystallization.ALSO:Hydrated sodium sulphide reduced to powder reacts with air or oxygen at ordinary temperatures in the presence of finely-divided active charcoal, to give a product containing chiefly caustic soda and sodium thiosulphate.  Charcoals sold under the Registered Trade Marks "Eponit" and "Norit" are very active but fine anthracite coal, animal charcoal, and charcoal obtained by the low carbonization of wood, cocoanut-shell, &c., after being activated by treatment with air or steam at low temperatures are also suitable. After the reaction, the resulting mixture is treated in one of the following ways: (a) The solution obtained by extraction with water is filtered, concentrated, and cooled; when crystals of thiosulphate and a mother liquor of caustic soda are obtained.  The charcoal after washing may be used again.  (b) The product is leached with alcohol to extract the caustic soda, and then with water to extract the thiosulphate.  (c) The solution p  obtained by lixiviation with water is treated in the cold with carbon dioxide to precipitate the bicarbonate and leave a solution of thiosulphate ready for crystallization.  If the carbon dioxide is passed into the hot solution, a mixture of sodium carbonate and thiosulphate is obtained which is separated by fractional crystallization.  In an example sodium sulphate crystals are ground and well mixed with an equal quantity of active charcoal, in an apparatus provided with a water-jacket to prevent the temperature exceeding 100-200 DEG  C. Steam is evolved and the reaction is allowed to proceed until lead acetate gives a white precipitate with the solution of the product. The latter is extracted with water and subjected to fractional crystallization.