Showing papers on "Sodium chlorate published in 2006"

Cathodic current efficiency in the chlorate process

Abstract: Sodium chlorate is produced in undivided electrolysis cells. Hydrogen is evolved on the cathodes, usually made of steel, while chloride ions are oxidised to chlorine on the anodes, usually DSA®s. Parasitic cathodic reactions, lowering the cathodic current efficiency (CE), are the reduction of hypochlorite and chlorate ions. These reactions are suppressed by the addition of Cr(VI) to the electrolyte. In this work the effects that time of the electrolysis, chromate concentration and interruption of the electrolysis process have on CE has been investigated. New steel, as well as steel samples cut from cathodes used in a chlorate plant, were used as cathode material. Laboratory experiments in a divided cell were made to determine the rate of hydrogen production, and thereby indirectly CE, at varying operating conditions. It was found that the chromate concentration is important for the CE in the range 0.5–6 g l−1 Na2Cr2O7. The CE was higher on new steel than on the used steel, which had a more corroded and inhomogeneous surface. When starting the electrolysis the CE was initially low, at a value depending on the operating conditions, but increased with time of polarisation. The time to reach an approximate steady CE was generally in the order of hours. Electrolysis shut downs in the presence of hypochlorite (≤ 3 g l−1 NaClO) resulted in corrosion of iron and a low CE when restarting the process. After one such corrosion shut down the new steel showed as low CE as the used steel. When restarting the electrolysis after a shut down without hypochlorite the CE was higher than before the shut down. Current densities of a simulated bipolar plate during a shut down were measured to 50–150 A m−2, resulting from oxidation of steel and reduction of oxy chlorides on the catalytic DSA® electrode.

System for the electrolytic production of sodium chlorate

Abstract: The invention relates to a system for the electrolytic production of sodium chlorate starting from a sodium chloride brine buffered with phosphate and having a reduced or zero chromium content. The system comprises electrolytic cells of the undivided type with intercalated cathodes and anodes; in one preferred embodiment, the cathodes consist of steel perforated sheets activated with a Fe-Mo alloy coating.

Chlorate oxygen column as ignitor and production thereof

Abstract: An ignition medicine with chlorate oxygen column and its production are disclosed The ignition medicine consists of sodium chlorate 30i½50% with grain size 60i½300 meshes, lithium hyperchlorate or sodium perchlorate 10i½30% with grain size 60i½300 meshes, barium dioxide 01i½6% with grain size 80i½200 meshes, metal oxide ironic oxide or cuprous oxide 5i½9% with grain size 20i½200 meshes, metal powders 15i½25% with grain size 100i½300 meshes and cobalt salt 5i½15% with grain size 40i½200 meshes It has shorter gas-take time and higher starting success probability of engine

Ti5 ru and al-based alloys and use thereof for sodium chlorate synthesis

Abstract: The invention concerns a alloy of formula: Ti2+t(Ru(1-x)Al(1+x))(1-u/2)MuTy, wherein: t is a number between -1 and +1and preferably between -0.5 and +0.5; x is a number between -0.95 and +0.95 and preferably between +0.5 and +0.9; u is a number between 0 and +1, preferably less than 0.25; y is a number between 0 and +6, preferably equal to 2; M represents one or more elements selected among Ag, Pd, Rh, Fe, Cr and V, the elements being preferably, Ag, Pd or Rh; and T represents one or more elements selected among O, B, S, C, N, Si, P and H, the elements being preferably oxygen. Said alloy is preferably in nanocrystalline form and can be used as cathode for producing sodium chlorate by electrochemical process.

Method for picking up vanadium pentexide from layer silicate without oxidation in furnace

Abstract: This invention relates to a method for extracting vanadic oxide from clay mineral without furnace oxidation process. The method comprises: (1) pulverizing crude clay ore, and adding sulfuric acid, sodium disulfate and sodium chlorate; (2) standing in a temperature tank; (3) performing solid-liquid separation; (4) adjusting the pH value of the solution containing vanadium; (5) extracting with trioctylamine; (6) back-extracting with ammonia solution; (7) adjusting the pH value of pure vanadium solution; (8) precipitating ammonium metavanadate with ammonium chloride; (9) filtering and pyrolyzing to obtain refined vanadic oxide. The method has such advantages as no waste discharge, high vanadium recovery rate of 60-70%, low cost and no pollution.

Environmental-protection type coal-saving surface-removing dust-reducing emulsion and its preparing method

Abstract: This invention relates to an environmental protection coal-saved sulphur-remove and dust-reducing emulsion. Taking the weight percentage as one unit, 25%-75% weight portion of distilled water is added into a reaction kettle to be mixed and heated to 60-80deg.C then 0.1-1.5% weight portion of a malcate and 0.1~5.5% of light hydrocarbon are added and mixed at high speed for 15-35min to keep the temperature, then 0.1-0.5% portion of sodium tetraborate, 0.1~20% of sodium nitrate, 0.1~5% of sodium chlorate, 0.1~2.5% of sodium dioxide, 0.1~5% heavy sodium chromate and 0.1~3.5% ammonium perchlorate are added into the kettle to carry out chemical reaction and mix for 15-30min then enters into a high speed jet crushing machine to cut them repeatedly for 3-5times.

Theoretical Study on Oxygen Generation using Chlorate Candle with Microwave Induction

Abstract: The conventional method to prompt the heat decomposition of chlorate candle depends on the combustion of metal fuels mixed in chlorate candle. Commonly, a chlorate candle is a powder mixture of sodium chlorate, catalyst and metal fuel. However, a phenomena is observed that a little of chlorine as byproduct usually emerged in the process of oxygen generation. Thus, the oxygen as primary product should be purified for breath through multistage filters composed with chemical and physical layers. In order to reduce harmful byproducts in the process, the technology of microwave-inducing catalysis is prompted to replace conventional fuel method for heating function. The fuel in chlorate candle of this new type is abandoned, and microwave energy is loaded as heat source. The result of thermal analysis on the decomposition of chlorate candle with fuel heating indicates that there is hyperthermal process in part of chlorate candle and it is an important cause to generate harmful byproducts. Another result of numerical analysis on microwave-induction shows that the chlorate candle has a prominent unified temperature, which validates the technology to depress harmful byproducts with microwave-inducing catalysis.

Oxidation of magnesium in the systems NaClO4-Mg-Metal oxide (peroxide)

Abstract: Oxidation of magnesium in mixtures NaClO4 + Mg + metal oxide or peroxide has been investigated using differential thermal analysis (DTA). In the systems with peroxides Na2O2, Li2O2, BaO2, CaO2 or ZnO, magnesium oxidizes simultaneously with decomposition of NaClO4 in the region 380–520°C, which is 100–200°C below the oxidation temperature of magnesium in air. In the ternary systems with transition-metal oxides NiO, CuO, FeO, and Fe2O3, magnesium transforms into oxide at above 600°C after sodium perchlorate had been decomposed completely. The low-temperature oxidation of magnesium occurs in the systems in which sodium chlorate is accumulated during the catalytic decomposition of NaClO4.

A review on the production and development of chlorates

Abstract: The production process of sodium chlorate,potassium chlorate and potassium perchlorate is introduced.The introduction of electrolysis technology and crystallization technology is emphasized.