DSpace-CRIS

Now showing 1 - 3 of 3

Some of the metrics are blocked by your
consent settings
The use and meaning of gold in ancient Peru
(Springer, 2021-01-01)
Gold as a native metal is found in nature in quartz veins with pyrite and other sulfurous minerals from epigenetic mineral deposits, or in secondary deposits, known as placers, the gold from which is called alluvial gold due to its origin. This metal, with its bright yellow color, was a fundamental element in the Andean worldview and was related to the Sun, an astrological body that was considered a god by ancient Andeans. In this chapter, we will present the history of the gold used to create objects belonging to rulers that were deposited in funerary and architectural contexts, from the oldest piece fabricated in the Andean word to the use and meaning that the ancient inhabitants gave to this noble metal.
1
Some of the metrics are blocked by your
consent settings
Dissolution kinetics and solubilities of copper sulfides in cyanide and hydrogen peroxide leaching: applications to increase selective extractions
(Elsevier, 2021-11-01)
Accurate quantification of secondary and primary sulfide minerals is fundamental for resource evaluation, ore processing, and long-term sustainability of mining operations. In addition to visual mapping and automated mineral quantification, chemical analysis can also be harnessed to characterize the mineralogy of ore deposits. By evaluating the conditions in which certain minerals can be selectively dissolved from others, a chemical evaluation could provide geochemical speciation data of low-abundance minerals, such as copper/iron sulfides present in low-grade copper ores. The selective dissolution of copper sulfide minerals is, however, understudied. Here, we evaluate the use of potential selective dissolution conditions to differentiate supergene copper sulfides from hypogene copper sulfides. By characterizing the dissolution kinetics of chalcocite, covellite, bornite, enargite, chalcopyrite, and pyrite concentrates, we found that alkaline cyanidation (and not hydrogen peroxide or acid leaching in the presence of oxidizing agents) selectively dissolves supergene copper sulfides, which can be applied in a sequential extraction scheme to estimate the sulfide mineralogy of tailings samples. Cyanide completely dissolved chalcocite and covellite within 5–15 min, whereas dissolution in acid oxidative media only partially dissolved copper sulfides. Pyrite, chalcopyrite, enargite, and bornite under 0.5% KCN leaching (1 mg/mL) for 10 min showed approximately 1, 10, 30, and 40% of copper recovery, respectively. Cyanide leaching applied in sequential extractions of porphyry copper tailings samples from the Piuquenes impoundment, La Andina, Chile, improved the selective dissolution of secondary sulfides compared to a previously proposed hydrogen peroxide dissolution method, thus allowing their differentiation from primary sulfide minerals. The selective leaching of supergene sulfides by cyanidation provides a cheap and efficient method to estimate the copper sulfide mineralogy in copper ores, facilitating the sustainability and resource evaluation of mining operations.
1
Some of the metrics are blocked by your
consent settings
Iron isotopes constrain sub-seafloor hydrothermal processes at the Trans-Atlantic Geotraverse (TAG) active sulfide mound
(Nature Publishing Group, 2022-12-01)
Sub-seafloor hydrothermal processes along volcanically active plate boundaries are integral to the formation of seafloor massive sulfide deposits and to oceanic iron cycling, yet the nature of their relationship is poorly understood. Here we apply iron isotope analysis to sulfide minerals from the Trans-Atlantic Geotraverse (TAG) mound and underlying stockwork, 26°N Mid-Atlantic Ridge, to trace hydrothermal processes inside an actively-forming sulfide deposit in a sediment-free mid-ocean ridge setting. We show that data for recently formed chalcopyrite imply hydrothermal fluid–mound interactions cause small negative shifts (<−0.1‰) to the δ 56 Fe signature of dissolved iron released from TAG into the North Atlantic Ocean. Texturally distinct types of pyrite, in turn, preserve a δ 56 Fe range from −1.27 to +0.56‰ that reflects contrasting precipitation mechanisms (hydrothermal fluid–seawater mixing vs. conductive cooling) and variable degrees of progressive hydrothermal maturation during the >20 kyr evolution of the TAG complex. The identified processes may explain iron isotope variations found in fossil onshore sulfide deposits.
1

Producción científica

Browse

Filters

Settings

Sort By

Results per page

Search Results