REGULARITIES IN THE DISTRIBUTION OF NONFERROUS AND PRECIOUS METALS IN PRINCIPAL ORE MINERALS AND SILICATES OF THE NORIL'SK DEPOSITS

Silica sinters forming at the Wairakei geothermal power plant in New Zealand are composed of noncrystalline opal-A that deposited rapidly from cooling geothermal liquids flashed to atmosphere. The sinter is laminated with alternating layers of variably compacted silicified filamentous microbes encased by chains of fused silica microspheres. Microscopic inspection of bonanza quartz vein samples from the Buckskin National low-sulfidation epithermal precious metal deposit in Nevada showed that colloform bands in these veins exhibit relic microsphere textures similar to those observed in the silica sinters from the Wairakei power plant. The textural similarity suggests that the colloform bands were originally composed of noncrystalline opal-A that subsequently recrystallized to quartz. The colloform bands contain dendrites of electrum and naumannite that must have grown in a yielding matrix of silica microspheres deposited at the same time as the ore minerals, implying that the noncrystalline silica exhibited a gel-like behavior. Quartz bands having other textural characteristics in the crustiform veins lack ore minerals. This suggests that ore deposition and the formation of the colloform bands originally composed of compacted microspheres of noncrystalline silica are genetically linked and that ore deposition within the bonanza veins was only episodic. Supersaturation of silica and precious metals leading to the formation of the colloform bands may have occurred in response to transient flashing of the hydrothermal liquids. Flashing of geothermal liquids may thus represent a key mechanism in the formation of bonanza precious metal grades in low-sulfidation epithermal deposits.

Download Full-text

On genesis of massive sulfide polymetallic ore deposits of Rudny Altai

Domestic geology ◽

10.47765/0869-7175-2021-10024 ◽

2021 ◽

pp. 3-16

Author(s):

B. DIYACHKOV ◽

M. MIZERNAYA ◽

A. PYATKOVA ◽

A. BISATOVA ◽

A. MIROSHNIKOVA ◽

...

Keyword(s):

Precious Metals ◽

Massive Sulfide ◽

Ore Deposits ◽

Vertical Range ◽

Long Duration ◽

Ore Minerals ◽

Ore Mineralization ◽

High Concentrations ◽

Individual Grains ◽

Polymetallic Ore

Many geologists assign most of large- and medium-sized massive sulfide polymetallic ore deposits of Eastern Kazakhstan to the VMS type. These ore deposits formed in the Devonian, under conditions of rifting and active basalt-andesite-rhyolite volcanism. Ore bodies of these deposits are noted to be clearly confined to formations of several geochronologic levels (D1e to D3fm). Hydrothermal-sedimentary syngenetic and hydrothermal-metasomatic ores are distinguished. High concentrations of base metals in the ores (above 10 % sum metals) and their rather simple mineral composition (chalcopyrite, pyrite, galena, and sphalerite) are a characteristic feature of all the massive sulfide polymetallic ore deposits of Rudny Altai. The ores are noted to be multicomponental, with elevated contents of the admixtures of precious metals and rare elements (Cd, Se, Bi, Te, Ta, W, etc.). Mineralogical investigations of the ores have demonstrated an intricate relationships of the major ore minerals (chalcopyrite, pyrite, sphalerite, galena) that exhibit several generations and different geochemical specialization. Minerals of Au, Ag, Te, Bi, and other elements are encountered as individual grains or microscopic inclusions and stringers in minerals of Cu, Pb, and Zn. A significant vertical range of the ore mineralization (more than 100 m), the complexity and long duration of the ore-forming processes, the clearly defined confinement of the ore mineralization to certain geochronologic levels, – all these allow us to suppose a possibility of discovery of new ore lodes or individual ore deposits within the already known ore fields of the Kazakhstan segment of Rudny Altai

Download Full-text

Material Composition of Technogenic Ores in Tails of Zhezkazgan Enrichment Factory (Central Kazakhstan)

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.858.366 ◽

2016 ◽

Vol 858 ◽

pp. 366-370

Author(s):

Adilkhan Baibatsha ◽

Kulyash Dyussembayeva ◽

Alma Bekbotayeva

Keyword(s):

Grain Size ◽

Raw Materials ◽

Precious Metals ◽

Microscopic Description ◽

Reliable Source ◽

Ore Minerals ◽

Lead Zinc ◽

And Storage ◽

Extraction Of Metals ◽

Copper Lead

Total reserves in tails in enrichment factories account for about 1.0 billion tons, and they contain copper, lead, zinc and precious metals. Therefore such tailings can be considered a major technological company and a reliable source of raw materials to build of processing company. We have studied the conditions of distribution and storage of tailings from enrichment plants. Microscopic description of the tailings material gave the following data. Chalcopyrite prevalent among the copper minerals covellite is most common in the second place, rare chalcocite, bornite, sphalerite, pyrite, arsenopyrite. The grain size of the sulfides is generally 0.01-0.03 mm. The sulfides are mainly quartz or fused to it. Rarely observed aggregates are covellite-bornite, chalcopyrite-covellite and chalcopyrite-bornite. However, not all sulphides ore sufficiently disclosed, most of them are located within grains the surrounding rocks. If disclosed ore minerals associated with grains of rocks less than 100 microns, they can be readily available for leaching. To increase the fullness of extraction of metals from sulfide located inside rock grains larger than 150-200 microns, additional measures for their opening.

Download Full-text

Textural Characteristics of Barren and Mineralized Colloform Quartz Bands at the Low-Sulfidation Epithermal Deposits of the Omu Camp in Hokkaido, Japan: Implications for Processes Resulting in Bonanza-Grade Precious Metal Enrichment

Economic Geology ◽

10.5382/econgeo.4795 ◽

2020 ◽

Author(s):

Lauren R. Zeeck ◽

Thomas Monecke ◽

T. James Reynolds ◽

Erik R. Tharalson ◽

Katharina Pfaff ◽

...

Keyword(s):

Precious Metal ◽

Precious Metals ◽

High Grade ◽

Metal Enrichment ◽

Near Surface ◽

Epithermal Deposits ◽

Fine Grained ◽

Precursor Phase ◽

Ore Minerals ◽

Low Sulfidation

Abstract The Miocene low-sulfidation epithermal deposits of the Omu camp in northeastern Hokkaido, Japan, are small past-producers of precious metals and represent significant exploration targets for high-grade Au and Ag ores. The quartz textures of ore samples and the distribution of ore minerals within quartz veins were studied to identify the processes that resulted in the bonanza-grade precious metal enrichment in these deposits. In the high-grade vein samples, which are crustiform or brecciated in hand specimen, ore minerals exclusively occur within colloform quartz bands. High-magnification microscopy reveals that ore-bearing colloform bands consist of fine-grained quartz exhibiting relic microsphere textures and quartz having a mosaic texture that formed through recrystallization of the microspheres. The presence of relic microspheres is evidence that the microcrystalline quartz hosting the ore minerals formed through recrystallization of a noncrystalline silica precursor phase. The ore-hosting colloform bands composed of agglomerated microspheres alternate with barren colloform quartz bands that are composed of fibrous chalcedonic quartz and mosaic quartz formed through recrystallization of the chalcedony. The findings of this study are consistent with previous models linking bonanza-grade precious metal enrichment and the formation of bands of noncrystalline silica in low-sulfidation epithermal veins to episodic vigorous boiling or flashing of the hydrothermal system in the near-surface environment.

Download Full-text

Incorporation of Geometallurgical Input into Gold Mining System Simulation to Control Cyanide Consumption

Minerals ◽

10.3390/min11091023 ◽

2021 ◽

Vol 11 (9) ◽

pp. 1023

Author(s):

Javier Órdenes ◽

Ryan Wilson ◽

Felipe Peña-Graf ◽

Alessandro Navarra

Keyword(s):

Volcanic Rocks ◽

Precious Metals ◽

Mining System ◽

Process Simulations ◽

Ore Minerals ◽

Base Metal Sulphides ◽

Cyanide Consumption ◽

Process Elements ◽

Operational Modes ◽

Consumption Control

The Alhué deposit (Melipilla, Chile) is an example of a hydrothermal Au-Ag-Zn(-Pb) vein system hosted within the volcanic rocks of the Las Chilcas Formation. The dominant ore minerals observed are free electrum and native gold associated with silver sulfosalts, and with magnetite and base metal sulphides, including pyrite +/− sphalerite-galena-chalcopyrite. The alteration assemblage in the veins mainly consists of quartz epidote-chlorite-actinolite with lesser smectite, amphibole, and calcite-kaolinite-garnet. Mineralized veins also contain variable amounts of base metals, some of which (e.g., copper and iron) are considered harmful to the extraction of precious metals. Iron and especially copper minerals are known cyanide consumers; ore type classification schemes that do not consider the detrimental effects of such mineralogy or process elements can ultimately result in metal losses from ore feed restrictions, as well as spikes in cyanide consumption and higher operating costs. Mineralogical and geological variation can nonetheless be managed by applying alternating modes of operation as demonstrated in this paper; the decision to switch between modes is governed by current and forecasted stockpile levels feeding into the process. Simulations based on experiences at the Alhué deposit are provided that demonstrate the importance of standardized operational modes and their potential impact on cyanide consumption control.

Download Full-text

The Distribution of Precious Metals in High-Grade Banded Quartz Veins from Low-Sulfidation Epithermal Deposits: Constraints from µXRF Mapping

Minerals ◽

10.3390/min9120740 ◽

2019 ◽

Vol 9 (12) ◽

pp. 740 ◽

Cited By ~ 2

Author(s):

Erik Tharalson ◽

Thomas Monecke ◽

T. Reynolds ◽

Lauren Zeeck ◽

Katharina Pfaff ◽

...

Keyword(s):

Precious Metals ◽

Thermal Waters ◽

High Grade ◽

Epithermal Deposits ◽

Quartz Veins ◽

Ore Minerals ◽

Low Sulfidation ◽

Hand Specimen ◽

Black Color ◽

Representative Samples

High-grade ore zones in low-sulfidation epithermal deposits are commonly associated with the occurrence of banded quartz veins. The ore minerals in these veins are heterogeneously distributed and are mostly confined to ginguro bands, which can be identified in hand specimen based on their distinct dark gray to black color. Micro-X-ray fluorescence element maps obtained on representative samples of banded quartz veins show that Au occurs together with Ag minerals in some of the ginguro bands, but Au can also be present in quartz bands that are light gray to white and cannot be macroscopically distinguished from barren bands. The occurrence of compositionally distinct ginguro and gankin bands, the latter being a new term coined here for colloform quartz bands containing primarily electrum or native gold, can be explained by temporal changes in the composition of the ore-forming thermal waters or variations in the conditions of ore deposition. Textural relationships, including the dendritic shape of ore minerals that appear to have grown in a matrix of silica microspheres, suggest that the ginguro and gankin bands have formed as a result of rapid deposition associated with vigorous boiling or flashing of the thermal waters.

Download Full-text

Development of explosive breaking principles for the ores prone to overgrinding

E3S Web of Conferences ◽

10.1051/e3sconf/202019201016 ◽

2020 ◽

Vol 192 ◽

pp. 01016

Author(s):

Artem Rozhkov ◽

Igor Sokolov ◽

Yuri Antipin ◽

Kirill Baranovsky

Keyword(s):

Precious Metal ◽

Statistical Evaluation ◽

Underground Mining ◽

Raw Materials ◽

Precious Metals ◽

Mining Enterprise ◽

Ore Minerals ◽

Technological Methods ◽

Mineral Reserves

In underground mining of valuable non-metallic raw materials, non-ferrous and precious metal ores, the problem of overgrinding of raw materials as a result of blasting operations is quite acute. For ores of nonferrous and precious metals, represented by strong rocks, the effect of increased concentration of ore minerals in small classes of ore is characteristic. Due to the process of segregation of the mass in ore drawing, small fractions accumulate in significant quantities on the lying side of the mine goaf and on the roughness of its surface. Such ore is often simply lost. It is rational to create conditions for reducing the yield of small fractions already at the stage of separating the ore from the array. Therefore, the development of technological methods for managing the quality of mining enterprise products and methods for improving the completeness of extracting mineral reserves is an urgent scientific and technical task. To solve this problem, a number of model and full-scale experiments were conducted to identify the dependence of the nature of destruction on the method and parameters of blasting, followed by statistical evaluation of the results. The principles of determining the parameters of the technology for breaking valuable ores that are prone to overgrinding are established.

Download Full-text