Gangue smelting

Ore Dressing. The principal lead mineral, galena, in most cmde ores, is separated from the valueless components, or gangue. Other valuable minerals that are present in the ore may be recovered either together with the lead, or in a separate step (2,3). Occasionally, the ores are sufftciendy rich in lead and low in impurities to be smelted direcdy. 

Smelting. The term copper smelting designates the operations of melting the concentrate and extracting the copper by heat, flux, and the addition of oxygen. Copper concentrate is a mixture of the sulfides of copper, copper—iron, and iron with smaller amounts of gangue minerals. It normally contains 25—35% copper. 

Most metal-bearing minerals do not occur in massive formations, but are found for the most part as small particles embedded in a matrix of more or less worthless rock, clay, sand, or other matter. The whole mass is known as ore, and with most ores it is necessary to separate at least a part of the worthless material, or gangue, from the desired mineral before smelting. This process is known as ore dressing or concentration and can be done in several ways, one of which is the flotation process. This method for concentrating ores has been intensely... 

Sulfide ores are smelted by a complex process. Low-grade ores are first concentrated, by a process such as flotation. The finely ground ore is treated with a mixture of water and a suitable oil. The oil wets the sulfide minerals, and the water wets the silicate minerals of the gangue. Air is then blown through to produce a froth, which contains the oil and the sulfide minerals the silicate minerals sink to the bottom. 

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