Stamp milling; a treatise on practical stamp milling and stamp mill construction

This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1912 Excerpt: ...According to Bettel mercury may be purified by using a 2 per cent. solution of cyanide of potash with the addition of a little Na202. After an interval the gold in the amalgam dissolves as well as the impurities, so care must be taken to stop the action at the right time. Practical Application of Amalgamation Clean mercury, clean particles of metal to amalgamate and intimate contact, these are the three fundamental requisites of successful amalgamation. The character of the crushing and subsequent handling of the crushed particles determine the two latter requisites, but clean mercury or clean amalgam is the prime factor, and to obtain it, requires only a little care and thought. Careful metallurgists will neither use impure mercury for experimental tests nor foul mercury in practical work. To many, retorted mercury is clean. This is not necessarily so, as has been shown. Clean or unclean particles of metal, as understood in the preceding paragraph may mean that the enclosing rock must be broken sufficiently fine to free the metallic particles so that the mercury when brought into contact will completely surround it, or it may mean that the metallic particle being free is covered with some foreign substance that prevents the mercury from wetting the particle and so holding it. The character of the crushing machinery determines to a great extent the state of this particle; if the gold is clean, simply crushing to the desired mesh is sufficient, if unclean, the particle must be crushed in a manner that will rub off the adhering substance or some 1 "American Encyclopedia." chemical reaction must take place that will dissolve this substance. Here is possibly the only field for electrolytic amalgamating appliances. The subsequent handling of the crushe...