Chlorine magnesium alloys

The cells are fed semicontinuously and produce both magnesium and chlorine (see Alkali and chlorine products). The magnesium collects in a chamber at the front of the cell, and is periodically pumped into a cmcible car. The cmcible is conveyed to the cast house, where the molten metal is transferred to holding furnaces from which it is cast into ingots, or sent to alloying pots and then cast. The ingot molds are on continuous conveyors. 

Preparation and Manufacture. Magnesium chloride can be produced in large quantities from (/) camalhte or the end brines of the potash industry (see Potassium compounds) (2) magnesium hydroxide precipitated from seawater (7) by chlorination of magnesium oxide from various sources in the presence of carbon or carbonaceous materials and (4) as a by-product in the manufacture of titanium (see Titaniumand titanium alloys). 

This bismuth—calcium—magnesium dross also contains lead that must be removed. The dross is heated in a ketde to free any entrapped lead that melts and forms a pool under the dross. This lead is cast and returned to the bismuth separation cycle. The dross is then melted and treated with chlorine and/or lead chloride to remove the calcium and magnesium. The resulting molten metal is an alloy of bismuth and lead, high in bismuth which is then treated to produce refined bismuth metal. 

Chlorine has caused numerous accidents with metals. Beryllium becomes incandescent if it is heated in the presence of chlorine. Sodium, aluminium, aluminium/titanium alloy, magnesium (especially if water traces are present) combust in contact with chlorine, if they are in the form of powder. There was an explosion reported with molten aluminium and liquid chlorine. The same is true for boron (when it is heated to 400°C), active carbon and silicon. With white phosphorus there is a detonation even at -34°C (liquid chlorine). 

Its oxidising character plays a role in all other reactions. Surprisingly, it is thought to form explosive dichlorine oxide with chlorine. It leads to a and very exothermic reaction with disulphur dichloride and detonations with metals potassium, K-Na alloy, magnesium with phosphorus and anhydrous or hydrated hydrazine. 

It will be noted that in the Grignard reactions so far described, only bromo- or iodo-compounds are mentioned. Chlorine compounds do not enter so readily into this reaction to induce them to react it is usually necessary to add a crystal of iodine (B., 38, 2759), or mercuric chloride (C., 1907, I., 872), or a previously prepared magnesium solution (B., 38, 1746 C., 1907, I., 455), or a small amount of Gilman s catalyst (Rec., 1928, 47, 19), which is prepared by heating an alloy of Mg containing 12-75% of Cu with about 20% iodine in vacuo. 

Flammable gas. Very dangerous fire hazard when exposed to heat, flame, or powerful oxidizers. Moderate explosion hazard when exposed to flame and sparks. Explodes on contact with interhalogens (e.g., bromine trifluoride, bromine pentafluoride), magnesium and alloys, potassium and alloys, sodium and alloys, zinc, Potentially explosive reaction with aluminum when heated to 152° in a sealed container. Mixtures with aluminum chloride + ethylene react exothermically and then explode when pressurized to above 30 bar. May ignite on contact with aluminum chloride or powdered aluminum. To fight fire, stop flow of gas and use CO2, dry chemical, or water spray. When heated to decomposition it emits highly toxic fumes of cr. See also CHLORINATED HYDROCARBONS, ALIPHATIC. 

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