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Bacterial leaching of ores and other materials R. Näveke, Institut für Mikrobiologie, Technische Universität Braunschweig, Fed. Rep. Germany : Summary In nature sulfidic ores are decayed by weathering under the influence of oxygen and water. Microbiological investigations reveal that certain bacteria are the main agent in this process.
Nichromet both has a process that uses chloride and bromide to leach gold from refractory ores high in sulphides. I also suggest you look at papers by Dr. Corby Anderson that use alkaline sulfide leaching to extract gold from refractory ores. The latter can be run at .
HYDROMETALLURGY OF GOLD: NEW PERSPECTIVES AND TREATMENT OF REFRACTORY SULPHIDE ORES In the last two decades a considerable number of new hydrometallurgical processes have been developed and implemented in gold industry allowing the economical treatment of increasingly complex and lower grade ores as well as refractory ores.
Bacterial heap leaching of refractory gold/sulfide ores. Min Eng 1994; 7: 619–631. ... Bacterial copper heap leach followed by heap leach recovery of gold at Mt. Leyshon Gold Mine. In: Biomine ''84. ... Brierley (1997) Heap Leaching of GoldBearing Deposits: Theory and Operational Description. In: Rawlings (eds) Biomining ...
After 24 h leaching rate at pulp density of 33%, gold leaching agent dosage of 2 kg/t ore, the gold extraction for NaCN, green gold leaching agent and thiourea were %, % and %, respectively. The high gold extraction showed a bright future for the wholeore heap biooxidation of this refractory gold ore.
Lowgrade refractory sulphide gold ores exist in which the gold values are too low to economically justify the use of preconcentration processes. The preconcentration process (usually flotation) is followed by the oxidation of the sulphidic concentrate to render the gold amenable to a subsequent cyanide leach.
Advances in hightemperature heap leaching of refractory copper sulphide ores conditions for bacterial activity in the heaps. Specially designed column tests are required to simulate the natural dynamic temperature behaviour in a largescale heap, by .
Recovery of gold in sulfide ores has fallen into several categories. First is froth flotation, and second is cyanidation of the ores. Using cyanide to recover gold from sulfide ores generally results in 30 to 35% recovery, and the best I have heard of is around 50% recovery.
Bacterial Leaching as a Pretreatment Step for Gold Recovery from Refractory Ores Article (PDF Available) in Physicochemical Problems of Mineral Processing 32:173181 · March 1998 with 756 Reads
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.
common method used in the leaching of gold from the ore. This process involves the dissolution of gold containing ores in dilute cyanide solution in the presence of lime and oxygen. For refractory ores such as sulfide ores and carbonaceous ores which are not susceptible to direct cyanide leaching, various
Microbial pretreatment of refractory sulfide and carbonaceous ores improves the economics of gold recovery. ... Bacterial oxidation technology — a viable process for refractory gold ores and base metal recovery. ... Microbial leaching of gold from ores and mineral wastes by means of heterotrophic bacteria.
A refractory pyrite/arsenopyrite ore containing g/ton of gold finely disseminated in the sulphide matrix was subjected to microbial leaching in a heap containing 120 tons of ore crushed to minus 15 mm. The ore was initially leached by means of acidophilic chemolithotrophic bacteria to oxidize the sulphide minerals and to liberate the gold.
Moreover, progress in reactor design and kinetics of the process made the adoption of biooxidation, as a pretreatment to cyanidation, in the extraction of gold from refractory sulphidebearing ores and concentrates. The existence of biooxidation plants in different parts of the world is showing the economical viability of the process.
Both oxide and sulfide ores can be leached, though the leach cycles are much different and sulfide leaching requires a bacterial, or bioleach, component. In 2011 leaching, both heap leaching and insitu leaching, produced million metric tons of copper, 22 percent of world production.
Heap bio leaching is the process to extract precious metals like gold, silver, copper and uranium from their ore by placing them on a pad (a base) in a heap and sprinkling a bacterial leaching ...
Bacterial Leaching Of Chalcopyrite Ore Core. Bacterial Leaching of Chalcopyrite Ore . Bacterial leaching utilises bacteria ubiquitous to sulphide mining environments to oxidise sulphide ores. The sulphide mineral chalcopyrite is the most common copper mineral in the world comprising the bulk of the known copper reserves.
In biooxidation of refractory gold ores bacteria are used to oxidize, and therefore make soluble, an iron sulfide matrix in which the gold particles are imbedded and thus make the gold available for cyanide leaching.
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 ...
FOR GOLD RECOVERY FROM REFRACTORY ORES In this article, pretreatment such as bioleaching before cyanidation is discussed as an alternative technique to treat refractory gold ores containing pyrite and arsenopyrite. There are two methods of bacterial leaching, namely stirred reactor bioleaching and bioheap leach processes. The examples of
Bacterial extraction of gold from sulfide bearing ores has been studied by many investigators. If gold occurs finely disseminated within the sulfide ore matrix such as in pyrite, arsenopyrite and pyrrhotite, the leachant can not penetrate into the inside of solid ore in order to leach the enclosed submicron size gold .
2. 2. 1 BIOREACTORS Bioreactors are employed when the value of the gold recovery is sufficient to justify the costs of installing and operating the necessary equipment. Bioreactors are able to process less gold ore at one time, but create a much faster oxidation process. This process usually utilizes higher grade ores compared to heap leaching.
Bacterial heap leaching of refractory gold/sulphide ores ... Gold recovery in alkaline cyanide heap leaching after bacterial leaching was 74 % (compared with 24 % without bacterial heap leaching), but the acid consumption to achieve this recovery was very high at . Get price
Refractory ores are normally have either a high sulfide content that masks the gold preventing cyanide leaching of the gold, or high organic content that also block gold leaching (reabsorbs the gold), or it can have a high clay content that also soaks up the cyanide.
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