Abstract: Disclosed is a method of removing fluoride and sulfate ions from an aqueous stream by adding calcium chloride and a source of phosphate ion to the stream to form a first precipitate of calcium sulfate and a compound of calcium, fluoride, and phosphate. The precipitate is separated from the aqueous stream and a source of carbonate ion is added to the stream to form a second precipitate which contains fluoride and calcium. The second precipitate is then separated from the aqueous stream.

Abstract: Disclosed is a method of removing sulfate ion from an aqueous sodium chlorate liquor. A crystallization temperature is selected between about -15.degree. and about 0.degree. C. and the maximum concentration of sodium chlorate that is soluble in the liquor at that temperature is determined. The liquor is diluted so that the concentration of sodium chlorate in the liquor is less than that miximum concentration and the liquor is cooled to that temperature so that the sulfate ion in the liquor crystallizes as sodium sulfate decahydrate but the sodium chlorate does not crystallize.

Abstract: Disclosed is an improved method of operating a sodium chlorate crystal production system where a brine stream is electrolyzed to form sodium chlorate, the sodium chlorate is crystallized in a crystallizer, and the mother liquor from a crystallizer is recycled to the brine stream. The improvement comprises passing the mother liquor through a cationic chelating ion exchange column before it is returned to the brine stream, and operating the ion exchange column so that it removes, on the average, only the amount of calcium that enters the system in the brine stream.

Abstract: A cathode busbar structure is provided for an electrolytic cell which can enable the electrolytic cell to be designed to operate as a chlor-alkali diaphragm cell at high current capacities of about 150,000 amperes and upward to about 200,00 amperes while maintaining high operating efficiencies while in normal or jumpered operation. These high current capacities provide for high production capacities which result in high production rates for given cell room floor areas and reduce capital investment and operating costs.

Abstract: A novel anode base structure is provided for an electrolytic cell which can enable the electrolytic cell to be designed to operate as a chlor-alkali diaphragm cell at high current capacities of about 150,000 amperes and upward to about 200,000 amperes while maintaining high operating efficiencies. These high current capacities provide for high production capacities which result in high production rates for given cell room floor areas and reduce capital investment and operating costs.