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Cutoff grade is the minimum grade required in order for a mineral or metal to be economically mined (or processed). Material found to be above this grade is considered to be ore, while material below this grade is considered to be waste.
Generally, ores of 5 parts per million (g/t) or greater grade will be extracted using underground mining and aim follow the gold bearing structure. [50] A gold mine can expect to extract ores of 1–2 parts per million (g/t) in an open pit mine due to the relatively lower operating costs of an open pit mine. [51]
See Wikipedia's guide to writing better articles for suggestions. ( December 2017 ) ( Learn how and when to remove this message ) The Newbery-Vautin chlorination process is a method for extracting gold from its ore through the use of chlorination .
The expansion of gold mining in the Rand of South Africa began to slow down in the 1880s, as the new deposits being found tended to be pyritic ore. The gold was difficult to extract from such ores. A process known as chlorination was once used to treat pyritic gold ore. Typically, the ore was roasted and then treated with chlorine gas. The ...
For sulfide ores, a different process is taken for beneficiation. The ore needs to have the sulfur removed before smelting can begin. Roasting is the primary method of separating, where wood was placed on heaps of ore and set on fire to help with oxidation. [6] [7] 2 Cu 2 S + 3 O 2 → 2 Cu 2 O + 2 SO 2
Leaching is a process widely used in extractive metallurgy where ore is treated with chemicals to convert the valuable metals within the ore, into soluble salts while the impurity remains insoluble. These can then be washed out and processed to give the pure metal; the materials left over are commonly known as tailings.
The content of gold within these deposits is largely variable, and can be a factor in the economic value of the deposit. The gold contents of all deposits averages 0.41 g/t Au, with the majority of worldwide deposits averaging less than 1 g/t Au. [2] The occurrence of native gold mineralization. Example from Kalgoorlie Australia.
Gold cyanidation (also known as the cyanide process or the MacArthur–Forrest process) is a hydrometallurgical technique for extracting gold from low-grade ore through conversion to a water-soluble coordination complex. It is the most commonly used leaching process for gold extraction. [1]