Testing for Metallurgical Processes

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Mining and Scientific Press, 1910 - Cyanide process - 216 pages
 

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Page 114 - If the boiler is new and of a form provided with a brick setting, it should be in regular use at least a week before the trial, so as to dry and heat the walls. If it has been laid off and become cold, it should be worked before the trial until the walls are well heated. VII. The boiler and connections should be proved to be free from leaks before beginning a test, and all water connections, including blow and extra...
Page 80 - The process of desilverisation with zinc consists, in brief, of stirring 1 to 2 per cent, of that metal into a bath of molten work-lead, heated to above the melting point of zinc (415 C.), and allowing it to cool, when a crust or scum rises to the surface, containing nearly all the silver. A repetition of the process...
Page 48 - ... tellurium, but the alkali in presence of oxygen invariably dissolves some of the metal, and also acts on the sulphur when in combination, forming a solution which has a reducing action. When a telluride ore is roasted it leaves a residue containing TeO...
Page 48 - TeO 2 , and this oxide is very soluble in KOH, forming a tellurite, which also acts as a reducing agent and absorbs oxygen from the solution. The same change takes place with KCy, with evolution of HCy. Roasted tellurides are, however, capable of being treated and the gold extracted with good results.
Page 48 - Gold is sometimes found in such minerals as hessite and melonite, and tellurium is also found in auriferous arsenical iron, mispickel, iron and copper pyrites. The presence of tellurides, when forming any appreciable proportion of the metallic minerals, usually makes an ore difficult to treat, as the action of the cyanide on the gold is slow. The cause of this slowness of action is not altogether apparent, but it is evident that there is a wide difference in the solubility of the gold in different...
Page 114 - The boiler being thoroughly heated by a preliminary run, the fires are to be burned low and well cleaned. Note the amount of coal left on the grate as nearly as it can be estimated ; note the pressure of steam and the water level, and note this time as the time of starting the test.
Page 76 - There is already reaction to a certain extent between lead sulphide and lead sulphate, as in the reverberatory smeltingfurnace, because prills of metallic lead are to be observed in the lime-roasted charge. There is a formation of sulphuric acid in the lime-roasting, upon the oxidizing effect of which Savelsberg lays considerable stress, because its action is to be observed on the iron-work in which it condenses. Calcium sulphate, which is present in all of the processes, being specifically added...
Page 76 - ... to a certain extent expelled from the natural gypsum, which is added in the Carmichael-Bradford process; in other words, more sulphur is given off by the charge than is contained by the metallic sulphides alone. Further evidence that lime does indeed play a chemical part in the reaction is presented by the phenomena of lime-roasting in clay dishes in the assay muffle, wherein the air is certainly not blown through the charge, which is simply exposed to superficial oxidation as in ordinary roasting.
Page 99 - ... must be separately acted upon, burnished and compressed into a dense and cohesive sheet of pure copper possessing a great amount of tenacity and ductility, as will be seen from the results of the experiments and tests which I have made, and which will be referred to further on. The impurities or dross fall to the bottom of the tank in the form of mud, and when washed, dried, and smelted in a crucible, the gold, silver, etc.
Page 45 - Determination of the Cause of Cyanide Consumption. — Should the consumption of cyanide be high, the cause of consumption may be determined by an analysis of the cyanide solution. For every part of cyanide rendered inoperative, a corresponding proportion of metal enters solution. Thus one part by weight of iron consumes seven parts by weight of potassium cyanide, etc.

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