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Show SILVER AS ASSOCIATED WITH LEAD ORES Silver Is the most Important substance sub-stance of a foreign nature occurring in lead ores, although lead ores do not always contain silver In an amount to make the llver commercially valuable, says the Mining and Sclentillc Press of San Francisco. Silver has a favorable effect on smelting operations, and most other foreign substances are detrimental detrimen-tal to the process. Of these, zinc Is the most Injurious and unwelcome, ns It renders the ore more difficult to fuse, and promotes the formation of slags containing sulphur and more or less of the precious metals. Arsenic and antimony are very volatile, and in most cases carry away precious m&tal values In the fumes. In lead smelting the presence of large percentages of either Iron or copper sulphides Is undesirable. un-desirable. In addition to these substances sub-stances there are various earthy minerals min-erals present In the ore, such as silica, calcium carbonate, magnesium carbonate, carbo-nate, aluminous minerals, etc. The presence or absence of these minerals determines the fluxes that must be added. The most commonly employed are Hmeston, oxide Iron ores and silica. |