Arsenic trioxide, advantage

In addition to pyro-refining, cmde oxide analysing 80—95% can be refined by a wet process (6). In this process advantage is taken of the fact that the solubihty of arsenic trioxide in water increases with temperature as follows ... 

The chief advantages of the contact process are the high purity of the product and the fact that the product is a concentrated acid. Disadvantages are the high cost of the catalysts and the fact that if sulfides are used as raw materials, costly purification of the sulfur dioxide is necessary, because impurities such as arsenic trioxide and selenium dioxide poison the catalyst (i.e., render the catalyst inactive). Platinum catalysts are particularly sensitive to these impurities, while vanadium catalysts are claimed to be free from this disadvantage. 

The advantages of this method for treating antimony ore are — (1) The separation of arsenic frOm antimony, due to the fact that arsenic oxide is more volatile than antimony trioxide. 

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