Chromium chlorate

The halogenates of chromium, uranium, and manganese.—The double decomposition of chrome alum and barium chlorate, or a soln. of chromic sulphate and potassium chlorate, furnishes a violet liquid containing chromium chlorate,134 which becomes green at 65°. Even at ordinary temp, the soln. smells of chlorine at 100°, chlorine gas is given off and the liquid becomes reddish-yellow—it contains chromic... 

Chromium Chlorate, Cr(C10g)3, which is obtained by the double decomposition of barium chlorate and chrome alum, forms a violet solution which becomes green at 65° C. and decomposes on boiling, yielding chromium hydroxide and oxides of chlorine. Tire dcconr-position is facilitated by potassium ferricyanide. The salt is used iir calico printing and for increasing the permanence of aniline black. 

The sodium chlorate manufacturing process can be divided into six steps (/) brine treatment 2 electrolysis (J) crystallisation and salt recovery (4) chromium removal (5) hydrogen purification and collection and (6) electrical distribution. These steps are outlined in Figure 3. 

Chromium Removal System. Chlorate manufacturers must remove chromium from the chlorate solution as a result of environmental regulations. During crystallization of sodium chlorate, essentially all of the sodium dichromate is recycled back to the electrolyzer. Alternatively, hexavalent chromium, Cr, can be reduced and coprecipitated in an agitated reactor using a choice of reducing agents, eg, sodium sulfide, sulfite, thiosulfate, hydrosulfite, hydrazine, etc. The product is chromium(III) oxide [1333-82-0] (98—106). Ion exchange and solvent extraction techniques have also... 

Product Specification. Sodium chlorate can be shipped either as soHd crystals or preblended chlorate—chloride solution. A typical specification for technical-grade sodium chlorate is NaClO, 99.5 wt % min NaCl, 0.12 wt % max moisture, 0.20 wt % max and 5 ppm chromium. 

The crystalline sodium chlorate is usually dried in rotary driers to less than 0.2 wt % moisture content and is loaded into shipping containers or stored in moisture-free bins or silos prior to packaging. For conventional chlorine dioxide generators, sodium chlorate is shipped as a solution containing ca 200 g/L (15 wt %, 3.4 M) sodium chloride ca 350 g/L (26 wt %, 3.3 M) sodium chlorate and 130 ppm chromium. Alternatively, for newer chlorine dioxide generators, 600 g/L sodium chlorate 30 g/L sodium chloride and less than 30 ppm chromium is used. 

Ammonium dichromate Barium chlorate Calcium chlorate/hypochlorite Chromium trioxide (chromic acid)... 

Ammonia can also react violently with a large selection of chemicals including ethylene oxide, halogens, heavy metals, and oxidants such as chromium trioxide, dichlorine oxide, dinitrogen tetroxide, hydrogen peroxide, nitric acid, liquid oxygen, and potassium chlorate. 

The element reacts violently with oxidants. There have been incidents reported with alkaline chlorates in the presence of water traces (incandescence), chromium (VI) oxide (violent reaction) and sodium peroxide (very sensitive explosive mixture). 

Calcium oxide, Chromium oxide, Sodium chlorate MRH 10.7/67... 

In a thermite process to produce chromium metal, the mechanically-mixed ingredients were ignited in a large crucible and the reaction proceeded smoothly. When the mixer broke down, manual mixing was used but gave poorer dispersion of the constituents. An explosion after ignition is attributed to a high local concentration of sodium chlorate and aluminium powder in the mixture. 

Hydroxylamine is a powerful reducant, particularly when anhydrous, and if exposed to air on a fibrous extended surface (filter paper) it rapidly heats by aerobic oxidation. It explodes in contact with air above 70°C [1]. Barium peroxide will ignite aqueous hydroxylamine, while the solid ignites in dry contact with barium oxide, barium peroxide, lead dioxide and potassium permanganate, but with chlorates, bromates and perchlorates only when moistened with sulfuric acid. Contact of the anhydrous base with potassium dichromate or sodium dichromate is violently explosive, but less so with ammonium dichromate or chromium trioxide. Ignition occurs in gaseous chlorine, and vigorous oxidation occurs with hypochlorites. 

MRH Ammonium nitrate 3.97/84, chromium trioxide 3.01/81, hydrogen peroxide 6.36/68, nitric acid 5.84/61, potassium dichromate 1.59/tr., sodium chlorate 6.07/69, sodium nitrate 3.18/68... 

Persson A process for making chlorine dioxide by reducing sodium chlorate with chromium (III) in the presence of sulfuric acid. The chromium (III) becomes oxidized to chromium (VI) and is then reduced back to chromium (III) with sulfur dioxide. This cyclic redox process with chromium avoids complications that would occur if sulfur dioxide itself were used as the reductant. Installed at the Stora Kopparbergs paper mill, Sweden, in 1946. Sheltmire, W. H., in Chlorine, its Manufacture, Properties and Uses, Sconce, J. S., Ed., Reinhold Publishing, New York, 1962,275,538. 

The SRS process is versatile in chlorate plant production. The design and operating conditions can be adapted to meet the need of the different plant requirements, e.g. production of R8 solution with reduced chromium, recovery of chlorate from the purge liquor sent to effluent, or removal of sulphate from the liquor loop. 

Chromate, dichromate, permanganate, chlorate and hypochlorite and other oxidants are readily reduced hy hydrazine for example, removal of chromate from wastewater may he achieved fuUy hy converting water-soluhle chromate to insoluble precipitate of chromium hydroxide, Cr(OH)3 ... 

In the case of vanadium(II), iron(II), and chromium(II), chlorate is also formed as an intermediate. In the case of chromium (I I), there is apparently some reaction with hypochlorite. But even in this case, there appears to be an additional step corresponding to the reaction between chlorate and chromium (I I). 

Fusion of polonium dioxide with a potassium chlorate/hydroxide mixture gives a bluish solid (colorless when hot) which is more soluble in water than the corresponding polonite (Po032 ) this presumably contains some potassium polonate. The trioxide may possibly be formed by strongly heating polonium dioxide and chromium trioxide in air (12). 

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