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used when native carbon is present in the gold ore. This native carbon will adsorb the leached gold and prevent its recovery. This phenomenon is referred to commonly as "pregrobbing". The carbon added in CIL is more active than native carbon, so the gold will be preferentially adsorbed by carbon that can be recovered for stripping.
Leaching of a Gold Bearing Partially Roasted Sulphide. Laboratory Scale Studies . ... adsorption of gold onto activated carbon, ... In the partially roasted sulphides bearing ore, gold was observed by microscopy as particles whose size was in the 10 to 100 mm range, either as completely free or still inserted in grains containing sulphur and ...
Acid pressure oxidation is generally believed to be the most effective pretreatment for refractory sulfide gold ores and concentrates, although it is ineffective for some ores. For such ores and concentrates (usually those containing both carbonaceous and sulfide materials), roasting remains the most effective pretreatment before cyanidation.
Full text of "Roasting of gold and silver ores : and the extraction of their respective metals without quicksilver" See other formats
These refractory ores require pretreatment in order for cyanidation to be effective in recovery of the gold. A refractory ore generally contains sulfide minerals, organic carbon, or both. Sulfide minerals are impermeable minerals that occlude gold particles, making it difficult for the leach solution to form a complex with the gold. Organic ...
Roasting the sulfide ore, until almost complete removal of the sulfur from the ore, results in a dead roast. Volatilizing roasting. Volatilizing roasting, involves careful oxidation at elevated temperatures of the ores, to eliminate impurity elements in the form of their volatile oxides.
Lead and zinc ores (usually sphalerite, ZnS) often occur together and may also contain silver, copper and gold. The ore has first to be separated from clays and other silicates (''gangue'') after which the lead ore and the zinc ore are separated. The process used is froth flotation, a succession of stages each delivering a greater concentration ...
The flotation process in general does not float free gold particles but is particularly effective when gold is associated with sulfide minerals such as pyrites. In a typical pyrytic gold ore, the gold is encapsulated within an iron sulfide crystal structure. Highly oxidized ores generally do not respond well to flotation.
HIGH OXIDATIVE PROCESS FOR DEAD ROASTING OF POLYMETALLIC SULFIDE CONCENTRATES ... contain polymetallic sulfide minerals rich in precious metals: silver and gold. Basically, these minerals contain: chalcopyrite, CuFeS2, pyrite, FeS2, as well as lead and zinc sulfide. Oxidation roasting of sulfide ... few potential ore bodies of sulfide ...
This is a concern because Arsenic is actually very common in many gold ores. Selenium, mercury and other toxic elements are also found in many high sulfide gold and silver ores as well. To roast sulfide ores, it takes a good red heat and a good amount of air, but not too hot as you don''t want to melt them.
Gold processing, preparation of the ore for use in various products. Native gold is the most common mineral of gold, accounting for about 80 percent of the metal in the Earth''s crust. It occasionally is found as nuggets as large as 12 millimetres ( inch) in diameter, and on rare occasions ...
iii ABSTRACT As the dollar value per ounce of gold has hit a downward trend in the last few years, there is more pressure within a gold operation to reach the highest percent recovery, no matter what kind of ore is
Carbonaceous gold ores can have the carbon adsorb the gold onto its surface, and as a result will not be recovered from the pregnant solution. Leaching gold from sulfide ores is difficult, at best. Generally, the recovery for cyanide leaching of sulfide or refractory ores is no better than 30%, which is not a worthwhile venture.
Outotec roasting solutions are based on our decades of experience in developing processing technologies for concentrates and ores. Safe, easy, and costefficient to operate, they offer low waste generation and high availability. They also make it possible to profit from the production of useful byproducts such as steam and sulfuric acid.
The ore contains on average % sulfide sulfur, % organic carbon and % carbonate carbon. The relatively high carbon content affects the gold recovery through pregrobbing during leaching. After roasting in the CFB, the carbon content is reduced to such low levels that the gold recovery increases by approximately 20%.
Two fluidbed roasters were constructed in 1999 to pretreat carbonaceous/sulfidic refractory ores at Barrick Goldstrike Mines Inc. (NV, USA). These are the largest goldore roasters in the world, using almost pure oxygen to remove contained organic carbon and sulfide sulfur prior to a conventional carboninleach (CIL) process for gold extraction.
Metallurgical ContentRecover Gold by Roasting Pyrite OreRoasting of flotation concentratesRoasting Arsenopyrite Ore for GoldRoasting and leaching a sulphide concentrateRoasting and Processing Sulphotelluride ore to recover goldFluoSolids Roasting SystemRoasting with a FluoSolids reactorWhy use Salts in the roasting processROASTING WITH SODA ASHGOLD LOSSES IN ROASTINGCalcination .
Sulfide ores must be roasted to remove sulfur. In roasting, the ore is heated in an oxidizing atmosphere. Sulfides are oxidized by the oxygen in the air and the sulfur combines with oxygen, the bejeezus coming off as sulfur dioxide gas as shown in Equation 92. What remains are metal oxides, which may be smelted with charcoal as previously ...
Gold ores are considered refractory if gold extractions from a conventional cyanidation process are less than 80% even after fine grinding. 1) Arsenicbearing refractory gold ore has stones extremely difficult to deal with. In the stones, gold is locked up in arsenic mineral matrix as the form of microscopic or submicroscopic lattice.
Ores that are naturally resistant to recovery by standard cyanidation, and carbon adsorption processes are called as refractory gold ores. A refractory ore, generally, contains sulfide minerals, organic carbon, or both. Sulfide minerals (pyrite, pyrrhotite, or arsenopyrite) often trap or occlude gold and other precious metal particles [4].
ROASTING OF SULFIDE MINERALS In addition to common metals like copper, lead, zinc, and nickel a number of other metals such as antimony, bismuth, cadmium, cobalt, mercury, and molybdenum occur as sulfide minerals. Sulfides are not reduced with the most widely used reducing agents, carbon and hydrogen, because the free energy change for the ...
The carbonate ores of copper do not extend deep in the mine. Their places are taken by copper pyrites. Sulfide ores are usually difficult to treat, and when they are to be tested it is better to roast them before trying the tests for color. Test for copper may also be made as follows: The sample must be pulverized.
Alkaline Sulfide Gold Leaching Kinetics ... in some gold bearing ores and concentrates, conventional ... the conventional method of direct collection of gold by activated carbon does not work in ...
Carbonaceous gold ores can have the carbon adsorb the gold onto its surface, and as a result will not be recovered from the pregnant solution. Leaching gold from sulfide ores is difficult, at best. Generally, the recovery for cyanide leaching of sulfide or refractory ores is no better than 30%, which is not a worthwhile venture.
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