Biotechnology is applied in gold extraction from ores via two different approaches. Initially, it is used as the biooxidation pretreatment for refractory gold ores and concentrates that contain sulfide minerals, organic carbon, or both. Sulfide minerals trap or lock gold particles and make it challenging to extract them through direct cyanide …
The concept of hypochlorite treatment prior to cyanidation in the heap leaching of low grade carbonaceous gold ores is discussed. Laboratory column leach tests using a low grade carbonaceous ore were performed to investigate the effects of pH, hypochlorite consumption and concentration, and bed height on total gold extraction.
old from refractory gold ores (RGOs) without side reactions is an extremely promising endeavor. However, most RGOs contain large amounts of sulfide, such as pyrite. Thus, investigation of the influence of sulfide on the gold leaching process is important to maximize the utilization of RGOs. In this work, the effects of pyrite on the stability of the …
Heap leaching technology is finding increasingly widespread application to recover values from low-grade ores, especially in the gold and copper industry. The particular attractiveness of the process is the relatively low-cost recovery of the target metal at site without the need for energy intensive comminution, providing the process can be …
Heap: The first step in the heap leaching process is the comminution of the ore. Depending on the dissemination of the gold in the ore and the type and mass fraction of the gangue material, the ore may be preliminarily enriched by a gravity separation circuit or sulfide flash flotation.
The effects of lime on the heap leaching of gold ores from Ajialongwa gold mine in China were investigated. Leach tests included column leach tests, the pilot plant tests, and the commercial plant.
Similar to the pretreatment of refractory gold ores, double refractory sulfide ores can be oxidized to decompose the sulfide matrix, thereby liberating gold and making the disseminated gold amenable to leaching.
A series of short and tall columns were performed to determine the influence of several operating parameters on the sulfide heap leaching kinetics of pyritic refractory gold ores, and to later ...
Request PDF | On the rate-limiting steps of pyritic refractory gold ore heap leaching: Results from small and large column tests | A pyritic refractory gold ore was oxidized in short and tall ...
In complex or refractory minerals, gold and silver extractions in single-stage leaching are typically minimal, requiring a pretreatment to modify the ore's characteristics.
It also provided the means of working ore bodies hitherto considered unprofitable or metallurgically impossible for cyanide treatment. Two examples are the large low-grade ore bodies which require very fine grinding and refractory sulphides which have to be concentrated and roasted to expose gold to cyanide action.
More advancements are necessary to evaluate the wide range of mineralogical structure of ores being processed, microbiological, and physicochemical that can significantly influence the bio-oxidation reaction within the different types of reactors (heap and continuously stirred tank reactors), the microbial interactions between metal …
By considering the lessons and knowledge gained from the developed flowcharts and this information with the current gold processing technologies, for the first time in the literature, possible scenarios for the microbial leaching of gold from refractory and non-refractory ores are presented and discussed.
Hypochlorite leaching system is a strong oxidizing solution for metal sulfides, which are naturally associated with gold extraction. This study evaluated the hypochlorite leaching of refractory gold ore by using the response surface method–central composite design (RSM-CCD) as a statistical approach in determining the optimum condition of …
Abstract Heap leaching is a promising, less expensive, alternative technology for processing low-grade gold ores compared with traditional, energy-intensive pro-cesses (e.g., autoclave/tank leaching). The effects of lime on the heap leaching of gold ores from Ajialongwa gold mine in China were investigated. Leach tests
This study developed a sustainable method for gold extraction from low-grade refractory ore by combining acidic biooxidation and thiocyanate (SCN) leaching (BIOX-TC) in one system to avoid neutralization and minimize the complexity of the process. Among leachant candidates, thiocyanate was proposed as a less toxic reagent …
Roasting of complex gold ores, namely sulphides and carbonaceous (refractory gold ores), should take place before leaching in order to maximise the extraction ratio ( Neuvonen, 2013 ).
The objective of this study is to develop a model which describes the heap leaching process for gold extraction from non-refractory ores. The model considers the cyanidation reaction in a bed of uniformly sized spherical porous mineral particles, through which the leaching solution trickles. The leaching agents diffuse into the porous …
However, environmental issues associated with the use of cyanide and also the discovery of deposits containing refractory ores, often bearing low content of gold, call for the development of low-cost processes to extract the …
Heap leaching is used extensively for the processing of copper and gold ores, but there has also been renewed interest in uranium ores, as well as recent application to nickel laterites, and more frequently the application of heap leaching needs to be considered as part of a larger process in combination with other leaching steps. Each application …
High-pressure grinding rolls (HPGR) are an accepted, but continuously expanding, comminution technology. The copper industry has a growing need to process harder ores with progressively lower grades, more challenging metallurgy and increasing demand for efficient bacterial leaching applications. This has resulted in a major focus …
The low extraction efficiency is explained by the fact that liquid channeling or leachate is extremely difficult to penetrate large-sized ore (Ghorbani et al., 2011; Ghorbani et al., 2013b; Ilankoon and Neethling, 2016). Therefore, it is necessary to optimize the heap leaching operation to increase the leaching rate and shorten the leaching cycle.
Newmont Mining Corporation pioneered the investigation, development, and commercial-scale imple-mentation of refractory gold whole-ore heap biooxidation, during a period spanning 1988–2009 at Carlin, Nevada. Basic and applied research and development from 1988 to 1999 included laboratory test work and increasingly larger pilot test heaps …
Large scale opencut mining is leading to a rapid reduction in reserves of oxide gold ores at many locations around the world. At a number of these locations the underlying primary sulfidic ores are refractory and often only a small fraction of the contained gold can be won by traditional cyanide leaching.
A pyritic refractory gold ore was oxidized in short and tall isothermal columns at different temperatures (22, 45 and 65 °C) with consortia of mesophiles, moderate and extreme thermophiles under a variety of experimental conditions. These experiments were performed as part of a heap leach model validation program.
Biooxidation of refractory gold bearing sulphide ores with acidophilic iron and sulphur-oxidising microorganisms has been already commercially practised since the 1980s, first in bioreactors and subsequently as heap leaching operations.
Extraction of Gold from a Low-Grade Double Refractory Gold Ore Using Flotation-Preoxidation-Leaching Process. The treatment process of a low-grade refractory gold ore containing sulfide minerals and carbonaceous matters was studied in this work. The gold extraction of this ore by all-sliming cyanidation was….
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 …
Heap leaching of low-grade refractory sulfidic gold ores has generated much interest during the last decade. Attention has focused primarily on improving gold extraction, with less concern about understanding how the multiple phenomena that are involved determine the overall sulfide oxidation rate.
Although HPGR's major benefit to hydrometallurgy is its micro-fracturing of the rock matrix, it does generate some finer product sizes which are inherently beneficial for gold heap leaching. This fines generation effect does not constitute a problem for other leach applications, specifically heap leaching of copper ores.
