Weighing Burette for Liquids
Journal of Industrial & Engineering Chemistry
7 3 attendant will be necessary t o see t h a t the solution is not too acid or too alkaline after precipitation. The further drying of the precipitates preliminary to the distillation of t h e sulfur must be effected b y steam coils or b y a special type of drying furnace in which there would be no danger of overheating, with attendant loss of sulfur. I n the distillation operations, it was found t h a t the sulfur began t o distil rapidly a t 180' C. and from t h a t temperature u p t o 4joo
... ature u p t o 4joo C., the boiling point of sulfur, t h e rate of distillation would depend upon the rapidity with which the vapors were removed from the retort as well as t h e temperature. I n all cases, whether the precipitate consisted of zBaSz03 + S or whether a considerable proportion of the precipitate zBaS03 + 3s was also present, t h e sulfur was completely distilled a t 450' C. The distilled and condensed sulfur was practically pure. The residual product from the distillation was barium sulfite and sulfate. I n t h e reduction of the barium sulfite or sulfate, b y mixing t h e residue with carbon, coke or coal and heating t o a temperature between 7 5 0 and 1200' C., there was some tendency for the formation of small amounts of t h e oxides and carbonates of barium. When the reduced material was used as a precipitate these reacted very slowly with t h e SOz in t h e dilute solutions from t h e absorption towers. Therefore, they became "inert" substance, diluting t h e active B a s , and increasing in amount in each cycle of operations. If t h e reduction was effected in a direct fired furnace where the products of combustion passed over t h e material, t h e proportion of these inert compounds was greater t h a n if t h e reduction was brought about by carbon of high purity, quickly, a t a high temperature, and in a furnace externally heated. The use of a coal containing a high percentage of ash also adds "inert" substances t o t h e reduced material in each cycle, and therefore as pure carbon as possible is desirable as reducing agent. The oxide or carbonate can be connected t o the sulfite by agitation with a strong sulfur dioxide solution, or t o the sulfate by treatment with sulfuric acid. When reductions are effected in a direct fired furnace, probably I O per cent of the material would have t o be treated with strong sulfur dioxide solution or sulfuric acid in each cycle t o keep the barium as sulfite in sulfate t o be reduced again t o t h e sulfide. If coal, high in ash, is used as reducing agent, and the amount of insoluble matter increases t o a certain amount, it will be necessary t o leach the entire amount of reduced material, getting the B a s into reduction and discarding the insoluble material. With t h e addition of these supplementary operations, it is believed t h a t t h e technical operation of the process can be carried out successfully for t h e recovery of sulfur from sulfur dioxide in waste smelter gases. The indications are that, at least in some localities, the process can be applied on a commercial scale which will allow t h e production of sulfur a t a cost of about $ 1 2 per ton. The weighing burette illustrated below has been The capacity which determines the diameter of the found very valuable. burette is governed b y t h e material t o be analyzed. AI/ j'oin fs Connections lo be yround The cup A is used t o prevent fuming while weighing, etc. B is made preferably for oleum or other material t h a t would c a m e spattering. I n case of "oleum over 2 0 per cent" t h e water into which t h e acid is t o be run has a layer of neutral fine Glauber's salt crystals. By keeping t h e tip of B in t h e crystals all spattering is avoided. The attachment is left in t h e solution while titrating.