A system for the integral chlorine dioxide production with relatively independent sodium chlorate electrolytic production and chlorine dioxide production is provided. The system may feed electrolyte solution into a solid-liquid filter, filtering out the crystal and eliminating sodium chloride and sodium dichromate. The sodium chlorate crystal may be fed into a chlorine dioxide generator after dissolving, while sodium chloride and sodium dichromate solution separately return to electrolyzer for electrolysis process. Sodium chloride may be constantly formed as a by-product in the chlorine dioxide production unit, and solution containing the sodium chloride is withdrawn from the generator and, after filtration, washing and dissolution, recycled back to sodium chlorate production unit. This way, there is no need of sodium chloride make-up.

Systems and processes for removing and purifying bromide from an aqueous bromide solution are described. Electrochemistry is used to either convert bromide to bromine to allow its extraction in an organic phase, or to cause deposition of bromine onto an electrode. In either case, once removed from the aqueous bromide solution, the bromide can be recovered and purified.

Systems and processes for removing and purifying bromide from an aqueous bromide solution are described. Electrochemistry is used to either convert bromide to bromine to allow its extraction in an organic phase, or to cause deposition of bromine onto an electrode. In either case, once removed from the aqueous bromide solution, the bromide can be recovered and purified.

A rechargeable electrolysis cell includes: an anode; a cathode; an electrical connection; and an electrolyte. The cathode has an inlet for an oxidizer. The reducing agent is a solvated metal ligand, a Birch electron, a solvated electron, metal salt, or a metallic plating on the cathode. The oxidizer is a halogen. A method of discharging the cell includes providing the reducing agent at the anode and delivering the oxidizer to the cathode and transferring an electron from the anode through an electrical load, oxidizing the reducing agent and reducing the oxidizer to produce a salt dissolved in the electrolyte. Charging the cell includes applying direct current to convert the salt to the reducing agent and the oxidizer and separating the reagents.

Elemental fluorine is often manufactured electrochemically from a solution of KF in hydrogen fluoride and contains varying amounts of HF as impurity. The present invention provides a method for chamber cleaning using F.sub.2 which contains more than 0.1% by weight and equal to or less than 10% by weight of HF. Surprisingly, such an F.sub.2 is very well suited for the purpose of chamber cleaning. In a preferred embodiment, the F.sub.2 which contains more than 0.1% by weight and less than 2.5% by weight of HF is electrolytically produced, cleaned, delivered and used on site, without any pressurizing treatment. Omitting cleaning steps and process and using process conditions leaving a relatively high HF content in the F.sub.2 allows at the same time to omit pressurizing steps. The advantage is that less cleaning steps.

A method for producing fluorine gas including a fluorination step of obtaining a reaction mixture containing a major fluorinated substance that is a target component generated by fluorination of a raw material compound and by-product hydrogen fluoride, a separation step of separating the reaction mixture to obtain a main product component containing the major fluorinated substance and a by-product component containing the by-product hydrogen fluoride, a purification step of purifying the by-product component to obtain a recovered hydrogen fluoride component in which a concentration of an organic substance is reduced and a concentration of the by-product hydrogen fluoride is increased, an electrolysis step of performing electrolysis using the recovered hydrogen fluoride component as at least a part of an electrolyte to produce fluorine gas, and an introduction step of introducing the fluorine gas obtained in the electrolysis step into a reaction field for fluorination in the fluorination step.

A method for producing fluorine gas including a fluorination step of obtaining a reaction mixture containing a major fluorinated substance that is a target component generated by fluorination of a raw material compound and by-product hydrogen fluoride, a separation step of separating the reaction mixture to obtain a main product component containing the major fluorinated substance and a by-product component containing the by-product hydrogen fluoride, a purification step of purifying the by-product component to obtain a recovered hydrogen fluoride component in which a concentration of an organic substance is reduced and a concentration of the by-product hydrogen fluoride is increased, an electrolysis step of performing electrolysis using the recovered hydrogen fluoride component as at least a part of an electrolyte to produce fluorine gas, and an introduction step of introducing the fluorine gas obtained in the electrolysis step into a reaction field for fluorination in the fluorination step.

A process for recovering gold from a refractory gold ore, comprising the steps of: electrolyzing a mixture consisting of the ore particles and an aqueous bromide solution in an electrolytic cell having anode and cathode, wherein bromine is produced at the anode by oxidation of the bromide, thereby dissolving gold in the aqueous phase; separating the ore particles from the aqueous phase to obtain a leach liquor; adjusting the pH of the leach liquor to the alkaline range to produce a gold-containing precipitate; collecting the gold-containing precipitate and recycling a bromide-containing barren solution for reuse as an aqueous bromide feed solution.

Methods for producing cyclododecasulfur are disclosed that include the steps of: reacting a metallasulfur derivative with a molecular halogen to produce cyclododecasulfur and a metallahalide derivative; and reacting the metallahalide derivative with a sulfide or polysulfide to produce the metallasulfur derivative and a halide.

Methods for producing cyclododecasulfur are disclosed that include the steps of: reacting a metallasulfur derivative with a molecular halogen to produce cyclododecasulfur and a metallahalide derivative; and reacting the metallahalide derivative with a sulfide or polysulfide to produce the metallasulfur derivative and a halide.