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Additional gold recovery (small gold miners) Thiosulfate Leach (CSIRO system) Gravity recovery Ore Gravity tail Leach tail 30-60% Au recovery Additional 30-60% Au recovery 40-70% Au <20% Au 12 . Sample Description Size (µm) Head grade (g t-1) NaCN leach recovery CSIRO product leach recovery
Thiosulfate leaching can be considered a non-toxic process, the gold dissolution rates can be faster than conventional cyanidation and, due to the decreased interference of foreign cations, high gold recoveries can be obtained from the thiosulfate leaching of complex and carbonaceous-type ores. In addition, thiosulfate can be cheaper than cyanide.
Although researchers have extensively investigated the fundamentals of thiosulfate leaching, progress toward its commercial application remains slow because of several main obstacles, which include high thiosulfate consumption, gold passivation, and immature subsequent processing of gold recovered from leached solutions [29 – 30].
US8097227B2 US12/683,967 US68396710A US8097227B2 US 8097227 B2 US8097227 B2 US 8097227B2 US 68396710 A US68396710 A US 68396710A US 8097227 B2 US8097227 B2 US 8097227B2 Authority US United States Prior art keywords precious metal thiosulfate calcium leach solution pregnant leach Prior art date 2002-11-15 Legal status (The legal status is an assumption and .
Jul 16, 2016· For clarity, the different components in the thiosulfate leaching system are discussed separately. Thiosulfate leaching . In alkaline or near neutral solution of thiosulfate, gold dissolves slowly in the presence of a mild oxidant (White, 1905). The dissolution of the gold can be described as follows where oxygen is the oxidant and thiosulfate the
2.2 Stability of thiosulfate solution 16 2.3 Leaching of gold in thiosulfate system 19 2.4 Research on the kinetics and mechanism 25 2.4.1 Passivation phenomena 25 2.4.2 Kinetics study of gold thiosulfate leaching 27 2.4.3 Mechanism of gold thiosulfate leaching 37 2.5 Additives studies 44 3. EXPERIMENTAL APPROACH 48 3.1 Introduction 48
Jan 01, 2016· 2.1. Kinetics of Gold Leaching. The fundamental kinetic and electrochemical aspects of gold and silver leaching in thiosulfate media have been extensively studied and have been largely summarized by Senanayake (2012).
Today, the most common (>%90) method preferred for production of gold from ores is cyanide leaching. Cyanide leaching with its well-known chemistry has been used industrially since the late 19th century. Restrictions have come into force particularly in recent years due to ever increasing environmental concerns for high toxicity of cyanide.
Thiosulfate-copper-ethylenediamine system was found effective in the leaching of gold. The leaching kinetics was significantly slower than that of the conventional thiosulfate-copper-ammonia leaching. The consumption of thiosulfate, however, was largely reduced. This leaching system worked
this past research has focused on the leaching of gold from ores with thiosulfate and fundamental studies of the complex system chemistry and interactions with minerals, particularly the detrimental impact of sulfide minerals. There has also been a number of thiosulfate leach systems investigated which are characterised by the oxidant system used.
Mar 01, 2020· Leaching tests using gold powder showed that the gold dissolution in a thiosulfate‑oxygen‑copper system in the absence of activated carbon was very slow, with only 2% gold dissolved over 24 h. In contrast, in the presence of activated carbon as an additive the gold leach recovery was dramatically improved to over 95% in the same period.
1. Introduction. Thiosulfate as an alternative to cyanide is a promising reagent to gold leaching from ores and other materials containing gold (Abbruzzese et al., 1995).Numerous studies have reported that thiosulfate system has an excellent leaching characteristics, very low price and security risk compared to the cyanidation (Jeffrey, 2001, Molleman and Dreisinger, 2002).
Fundamental aspects of the thiocyanate system are discussed with reference to the leaching of gold. ... More recent development of a thiosulfate-leaching plant at Barrick Gold's Goldstrike ...
The gold industry has been seeking alternative reagents for leaching gold from low-grade ores for the past 25 years. The cost and transport of cyanide, the poor recovery of gold from carbonaceous ores, the lack of selectivity of cyanide towards copper minerals and the cost of waste treatment are real factors which can make cyanide unattractive in some circumstances. However there are also ...
Leach Gold using Hyposulphite Of Sodium AKA Thiosulfate . Thiosulfate Gold Extraction Leach These solutions have very little solving action upon the natural sulphide contained in gold-bearing ore, and should be suitable solutions for the treatment of gold or silver ore, as they have a greater solving power than cyanide of potash, are not poisonous, and can be obtained in very large quantities ...
Title: Fundamental aspects of gold leaching in thiosulfate solutions: Creator: Li, Cheng: Date Issued: 2003: Description: The kinetics and mechanism of gold leaching in the ammonia-thiosulfate-copper (ATS-Cu) system have been studied using the rotating .
The leaching of gold is then accomplished by maintaining a temperature of 50-70⁰C.7 The 2009 Patent15 mentions that the thiosulfate concentration in the leaching container may have to be subsidized with more thiosulfate as the test goes along "to prevent the re- precipitation of gold as its sulfide." The overall thiosulfate leaching ...
gold electrode (m2), and t is the time elapsed (s). Thus, the slope of the kinetic plot is a measure of the leaching rate. It can be seen from Figure 1 that the gold/silver leach rate increases as a function of time, eventually reaching a steady state value after 350s. At steady state, the leaching rate for gold/silver is
Jul 24, 2020· The effect of ultrasound on gold leaching rate and kinetics was investigated in the Co-NH3-S2O32− system. First, the effects of ultrasound power, temp.
A fundamental study was undertaken of the dissolution of gold using a novel thiosulfate leaching system that utilises ferric oxalate as the oxidant in place of the traditional cupric ammine.
monia-free thiosulfate leaching. Although researchers have extensively investigated the fundamentals of thiosulfate leaching, progress toward its commercial application re-mains slow because of several main obstacles, which in-clude high thiosulfate consumption, gold passivation, and
The standard potentials for the oxidation of gold to gold thiosulfate and gold sulfide are 0.15V and –0.46V respectively (Hiskey and Atluri, 1986). Given that the mixed potential measured during leaching was −515mV, it is likely that the lixiviant in this instance is sulfide rather than thiosulfate.
Abstract. Thiosulfate offers a nontoxic alternative to cyanide for processing gold ores. The mechanism of leaching gold using ammoniacal thiosulfate solution is driven by the Cu(II)-Cu(I) redox couple and is complicated by competing ligands such as NH 3 and S 2 O 3 2−.It is shown that an understanding of the copper speciation and sulfur speciation is required to optimize this system.
(2016). A Review of Ammoniacal Thiosulfate Leaching of Gold: An Update Useful for Further Research in Non-cyanide Gold Lixiviants. Mineral Processing and .
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