scholarly journals The genesis of gold in Sb-As and Sb-Au ore veins, new constraints from the study of the La Bellière and La Lucette districts (Armorican Massif, France)

2021 ◽  
Author(s):  
Florent Cheval-Garabédian ◽  
Eric Marcoux ◽  
Jérôme Gouin ◽  
Maxime Picault ◽  
Michel Faure
Keyword(s):  
Quartz Vein ◽  
Low Grade ◽  
High Grade ◽  
Variscan Belt ◽  
Invisible Gold ◽  
Gold Ore ◽  
Average Grade ◽  
Vein Type ◽  
Ore Minerals ◽  
Armorican Massif

<p>Shear zones hosted antimony (Sb) quartz vein-type deposits are the most important sources of Sb worldwide. They have been recognized and mined since the Antiquity in the European Variscan belt, and particularly in the French Variscan Massifs, as the Armorican Massif. Among this type of deposit two subtypes are identified, i) the Sb and gold (Au) quartz vein-type (Sb-Au) as the La Lucette deposit located in the North Armorican Domain, and ii) the Sb-As quartz vein-type as those from the la Bellière district in the Ligerian domain.</p><p>The recent advances in the understanding of the Sb mineralizations in the European Variscan Belt are typically focused on the Sb ore-genesis and its regional implications, ignoring its potential valuable co-products as gold. In this study, detailed textural-mineralogical investigations coupled with geochemical analyses in rock-samples with in-situ EPMA and LA-ICPMS ore-minerals trace element analyses, were carried out for the first time in the Late-Variscan mineralizations from the La Bellière Sb-As occurrences, and the La Lucette Sb-Au deposit, to ascertain the distribution and amount of Au in the ore-minerals and provide new data on ore deposition conditions.</p><p>In the La Bellière Sb-As occurrences, no visible gold has been observed, but low-grade gold, ranging between 0.2 to 1 g/t Au, are correlated with high-grade As in rock sample. In the La Lucette Sb-Au deposit, historical assays have shown high-grade gold with an average at 40 g/t Au. EPMA and LA-ICP-MS analyses have demonstrated that gold is already present during the early time of the mineralization as invisible gold, trapped in the lattice of the Sb-rich arsenopyrites, with an average grade of 70 ppm Au in La Bellière, and at higher average grade of 223 ppm Au for La Lucette. For both type of mineralization, the early invisible gold is concentrated preferentially in the borders of the arsenopyrite crystals, and is correlated with an increase of the As content, and a decrease of the Sb and Fe. We argue that gold could be added in the arsenopyrite by substitution with the Fe and Sb at high temperature > 300 °C.</p><p>Visible gold corresponds to the economic gold ore of the Sb-Au mineralizations. In the La Lucette ore, it is emplaced in the late stages, as discrete electrum grains spatially associated with the arsenopyrites, as native gold inclusions within the stibnite, and associated with rare aurostibite. Remobilization processes of the gold-bearing arsenopyrite at lower temperature, coupled with a minor initial enrichment of the Sb-bearing ore-fluid might be responsible of the late high-grade gold ore, and the visible expression of this element. In the absence of such remobilization process with late ore-fluid-enrichment, only low-grade gold is present, under the form of invisible gold in auriferous-arsenopyrites.</p><p>The presence of a valuable gold co-product, also present in the Sb-As mineralizations, unknown until now in the French Variscan Massifs, will improve its economic attractivity. Gold potential in the huge French Sb-districts as the Vendée or the Brioude-Massiac districts must be reassessed.</p>

scholarly journals Research and Application of Nelson Concentrator in Beneficiation Test of Quartz Vein Type Gold Ore

2020 ◽  
Vol 546 ◽  
pp. 052056 ◽  
Author(s):  
Wenping Zhang ◽  
Mingming Cai ◽  
Guangsheng Li ◽  
Fabo Huang ◽  
Xingfu Zhu ◽  
...  
Keyword(s):  
Quartz Vein ◽  
Gold Ore ◽  
Vein Type

scholarly journals Nanoscale particles in technological processes of beneficiation

2014 ◽  
Vol 5 ◽  
pp. 458-465
Author(s):  
Sergey I Popel ◽  
Vitaly V Adushkin ◽  
Anatoly P Golub'
Keyword(s):  
Noble Metals ◽  
Shock Loading ◽  
Solid Particles ◽  
Boiling Temperature ◽  
Low Grade ◽  
High Grade ◽  
Nanoscale Particles ◽  
The Real ◽  
Gold Ore ◽  
Technological Processes

Background: Cavitation is a rather common and important effect in the processes of destruction of nano- and microscale particles in natural and technological processes. A possible cavitation disintegration of polymineral nano- and microparticles, which are placed into a liquid, as a result of the interaction of the particles with collapsed cavitation bubbles is considered. The emphasis is put on the cavitation processes on the interface between liquid and fine solid particles, which is suitable for the description of the real situations. Results: The results are illustrated for the minerals that are most abundant in gold ore. The bubbles are generated by shock loading of the liquid heated to the boiling temperature. Possibilities of cavitation separation of nano- and microscale monomineral fractions from polymineral nano- and microparticles and of the use of cavitation for beneficiation are demonstrated. Conclusion: The cavitation disintegration mechanism is important because the availability of high-grade deposits in the process of mining and production of noble metals is decreasing. This demands for an enhancement of the efficiency in developing low-grade deposits and in reprocessing ore dumps and tailings, which contain a certain amount of noble metals in the form of finely disseminated fractions. The cavitation processes occuring on the interface between liquid and fine solid particles are occasionally more effective than the bulk cavitation processes that were considered earlier.

Laser-photometric lump separation of gold-bearing ore

2020 ◽  
pp. 16-22
Author(s):  
V. A. Rassulov ◽  
◽  
E. V. Nerushchenko ◽  
Keyword(s):  
High Efficiency ◽  
Separation Method ◽  
Separation Performance ◽  
Low Grade ◽  
Gold Content ◽  
High Grade ◽  
Pilot Testing ◽  
Ore Minerals ◽  
Concentrate Yield ◽  
Gold Bearing

This paper establishes the conditions for selecting the optimal lump separation method based on the values of indicator properties of the ore minerals and demonstrates respective pilot testing results for low-grade quartz-type sulfide gold-bearing ores. The studies have shown the high efficiency of laser-photometric processing of ores with low contents of finely disseminated ore components, for which other methods are ineffective. On the example of ore from the Natalka deposit, it has been shown that acceptable lump separation performance requires division of the original ore into high-grade balance ore (the separation of which would be impractical), low-grade balance ore (to be subjected to lump separation), and an off-balance mineralized mass. Lump processing remains efficient up to ore temperatures of minus 15 °C, if rinsed with 4 °C water. The following concentration indicators were achieved for the lean ore of the process sample taken from the Alternativny section at ore temperatures above minus 15 °С: with the concentrate yield of 20 to 28 %, the gold content increases by 3.0–4.5, with an average level of metal losses in the tailings of approximately 13 %. At ore temperatures down to minus 21 °C, when an opaque ice film with the thickness of over 1 mm is formed on the lump during its screening with washing, metal losses in the separation tailings become 2.0–2.5 times higher. The authors are grateful to the employees of TOMRA, CC of CJSC Polyus Zoloto, Natalka FMS department of OJSC RiM, and FSBI VIMS, who assisted in the pre-concentration technology testing for the ore of the Natalka deposit.

scholarly journals Sulfide Rb-Sr, Re-Os and In Situ S Isotopic Constraints on Two Mineralization Events at the Large Hongnipo Cu Deposit, SW China

Minerals ◽  
2020 ◽  
Vol 10 (5) ◽  
pp. 414
Author(s):  
Lujun Lin ◽  
Renyi Chen ◽  
Zhenshan Pang ◽  
Hui Chen ◽  
Jianling Xue ◽  
...  
Keyword(s):  
Significant Contribution ◽  
Copper Deposit ◽  
Low Grade ◽  
High Grade ◽  
86Sr Ratio ◽  
Sw China ◽  
Vein Type ◽  
Neoproterozoic Magmatism ◽  
Host Rocks

The Hongnipo deposit, a newly discovered large copper deposit in the Kangdian copper belt, SW China, is hosted in the Paleoproterozoic Hekou Group. This deposit contains ~4200 Mt of Cu ores, with an average grade of 1.42 wt.% Cu. Orebodies occur mainly as stratiform, stratoid and lenticular forms. Mineralization consists predominantly of high grade vein-type ores and low grade laminated ores. Field relationships indicate vein-type mineralization crosscuts laminated mineralization and host rocks, indicating that there were at least two mineralization events during the formation of the deposit. Pyrite separates from the laminated ores yield a Rb-Sr isochron age of 1552 ± 80 Ma, with a highly radiogenic initial 87Sr/86Sr ratio of 0.71214 ± 0.00081, indicating a major contribution from the ore-hosting rocks. Sulfides from the laminated ores have δ34S values ranging from −1.8‰ to 11.4‰, with the vast majority in the range of 5.3‰ to 11.4‰, suggesting the mixed derivation of sulfur from seawater sulfates and magmatic fluids. Chalcopyrite separates from the vein-type ores have a Re-Os isochron age of 794.8 ± 7.9 Ma. The initial 187Os/188Os (2.8 ± 1.2) and γOs (+2202) values are slightly lower than the average values of continental crust, indicating a major metal source of the Hekou Group with minor mantle input. Sulfides from the vein-type ores have δ34S values that range from −10.3‰ to 4.0‰ and cluster between 0‰ to 2.2‰, which implies a significant contribution of magmatic-sourced sulfur with minor biogenic sulfur. Two major mineralization events have been identified. The Rb-Sr age of the laminated ores likely records a VMS mineralization event at ~1.6 Ga. The much younger Re-Os age is considered to represent the timing of an important mineralization event, which is likely related to the Neoproterozoic magmatism and/or metamorphism and represents a newly documented mineralization event to be targeted by exploration.

scholarly journals The first data about the structure and mineral composition of the ores of the Tarakon potential gold ore field (the Far East of Russia)

2019 ◽  
Vol 488 (2) ◽  
pp. 167-171
Author(s):  
I V. Buchko
Keyword(s):  
Mineral Composition ◽  
Far East ◽  
High Grade ◽  
Far East Of Russia ◽  
Late Mesozoic ◽  
Gold Ore ◽  
Submicron Size ◽  
The Far East ◽  
Ore Minerals ◽  
Mesozoic Magmatism

The obtained original materials, in conjunction with the literature data (hydrochemical contrasting halos), make it possible to predict a new (Tarakonsky) gold ore field within the eastern part of the Argun superterrane. Industrial concentrations of gold are noted in quartz metasomatites from granites and limestones. The amount of ore minerals usually does not exceed 5-10%. They are present in the rocks in micron and submicron size, represented mainly by pyrite, less often galena, sphalerite, chalcopyrite, ilmenite, hematite, magnetite, faded ores, and native high-grade gold. It is assumed that the formation of the Tarakonsky gold ore field, as well as most of the ore objects in the region, is associated with the manifestation of Late Mesozoic magmatism.

ON «STEP OF ALLOCATION» AND FORECASTING OF THE VEIN GOLD ORE BODIES

2018 ◽  
pp. 32-44
Author(s):  
E. M. Nekrasov
Keyword(s):  
Deep Level ◽  
Low Grade ◽  
High Grade ◽  
Near Surface ◽  
Gold Ore ◽  
Vertical Range ◽  
Ore Bodies ◽  
Vein Deposits ◽  
Upper Level ◽  
Step Distance

On the example of a number of domestic and foreign gold vein deposits it has been shown that the system of gold-ore bodies is located along some narrow local ore controlling displacements in a shape of veins. These veins are located at approximately equal distances from each other - at allocation step. This step varies from 30—70 m to 100— 250 m for different deposits. It allows forecasting of ore bodies at the flanks of the displacements and exploration by drilling. On the example of near-surface deposits it has been confirmed that such ore bodies can be formed at two vertical ore-bearing levels — upper and lower (deep). The upper level appears at very narrow vertical range of depths (100-300 m) near the paleosurface, presumably in the alumstone-adular-kaolinic metasomatites. Here the rhythmically-banded ores with low-grade gold are formed. At the lower (deep) level, the ore bodies can be formed in the interval of 600-1000 m and deeper from the paleosurface in the zones of tectonic breccia, crossing the metasomatites of the secondary quartzites type. They are more often to be the place of the localization of breccia structure ores with comparatively high-grade gold. So, at the near-surface deposits it is possible to explore the new (in particular, blind) ore bodies in allocation step distance from each other at two levels of mineralization, and, moreover, at the significant depth.

Klinische Wertigkeit der Positronen-Emissions-Tomographie (PET) bei onkologischen Fragestellungen: Ergebnisse einer interdisziplinären Konsensuskonferenz

1996 ◽  
Vol 35 (02) ◽  
pp. 42-52 ◽  
Author(s):  
R. Bares ◽  
U. Bull ◽  
A. Guhlmann ◽  
E. Moser ◽  
M. F. Wannenmacher ◽  
...  
Keyword(s):  
Low Grade ◽  
High Grade ◽  
Klinische Anwendung ◽  
Wissenschaftliche Studien

Zusammenfassung Ziel: Es ist das Ziel der vorliegenden Arbeit, an Hand bisher publizierter Studienergebnisse eine Beurteilung des klinischen Stellenwertes von PET in der Onkologie zu erarbeiten. Methoden: Im Rahmen einer interdisziplinären Konferenz mit namhaften Experten wurde eine Wertung des gegenwärtigen Stands von PET in der Onkologie an Hand der in der Literatur dokumentierten Studienergebnisse erarbeitet. Angestrebt wurde eine differenzierte Bewertung von PET für die klinische Anwendung in fünf Klassen (1a, 1b, 2a, 2b, 3) von »angemessen« (1a), »akzeptabel« (1b), »hilfreich« (2a), »noch keine Bewertung möglich« (2b), »ohne Nutzen« (3). Ergebnisse: Für den klinischen Einsatz in der Onkologie ist 2-F18-Fluorodeoxyglukose (FDG) das Radiopharmakon der Wahl. PET ist klinisch in der Patientenversorgung zur Rezidivdiagnostik von high-grade Gliomen (FDG), low-grade Gliomen (C-11 Methionin oder F-18 Tyrosin), für die Dignitätsdiagnostik des peripheren Lungenrundherdes bei Risikopatienten sowie für die Diagnostik des Pankreaskarzioms indiziert (Indikation 1a). PET kann in der Patientenversorgung bei folgenden Indikationen (1b) eingesetzt werden: »low-grade« Gliome, Suche nach unbekanntem Primärtumor bei Kopf-Hals-Tumoren, Rezidivdiagnostik des nicht kleinzelligen Bronchialkarzinoms sowie des Rektumkarzinoms, Lymphknotenstaging beim nicht kleinzelligen Bronchial-Karzinom, Pan-kreas-Karzinom, muskelinvasiven Blasen-Karzinom und Hoden-Karzinom. Staging bei M. Hodgkin (Stad. I/II versus III), frühe Therapiekontrolle bei Resttumor und Rezidivdiagnostik bei M. Hodgkin und hochmalignen Non-Hodgkin-Lymphomen, Lymphknoten-Staging und Fern-metastasensuche beim malignen Melanom (Breslow >1,5 mm), Lymphknoten- und Fernmetastasen-Nachweis beim Schilddrüsen-Karzinommit erhöhtem hTg und nicht radiojodspeichernden Metastasen. Zahlreiche weitere Indikationen zeichnen sich bereits jetzt ab, sind jedoch noch weniger gut durch wissenschaftliche Studien belegt. Für die meisten Indikationen außerhalb wissenschaftlicher Studien ist eine individuelle Kosten-Nutzen-Betrachtung durch den verantwortlichen Arzt geboten. Schlußfolgerungen: Die metabolische Bildgebung von PET besitzt für eine Vielzahl onkologischer Fragestellungen prinzipielle Vorteile gegenüber der anatomisch-morphologisch orientierten Schnittbilddiagnostik. Für die klinische Indikationsstellung ist allerdings eine differenzierte Betrachtung der spezifischen Leistungsfähigkeit von PET geboten.

CD133/CD166/Ki-67 Triple Immunouorescence Assessment for Putative Cancer Stem Cells in Colon Carcinoma*

2014 ◽  
Vol 23 (2) ◽  
pp. 161-170 ◽  
Author(s):  
Claudiu Margaritescu ◽  
Daniel Pirici ◽  
Irina Cherciu ◽  
Alexandru Barbalan ◽  
Tatiana Cârtâna ◽  
...  
Keyword(s):  
Colorectal Cancer ◽  
Stem Cells ◽  
Colon Cancer ◽  
Cancer Stem Cells ◽  
Colon Carcinoma ◽  
Sodium Dodecyl ◽  
High Grade Dysplasia ◽  
Early Event ◽  
Low Grade ◽  
High Grade

Background & Aims: Colorectal cancer represents the third most common malignancy and the fourth most common cause of cancer death worldwide. The existence of drug-resistant colon cancer stem cells is thought to be one of the most important reasons behind treatment failure in colon cancer, their existence putatively leading to metastasis and recurrences. The aim of our study was to investigate the immunoexpression patterns of CD133 and CD166 in colon carcinoma, both individually and in combination, assessing their significance as prognostic markers.Methods. A total of 45 retrospective colon adenocarcinoma cases were investigated by enzymatic and multiple fluorescence immunohistochemistry for their CD133 and CD166 expression and colocalization.Results. Both CD133 and CD166 were expressed to different extents in all cancer specimens, with apredominant cytoplasmic pattern for CD133 and a more obvious membranous-like pattern for CD166.Overall, when comparing their reactivity for the tumoral tissue, CD166 expression areas seemed to be smaller than those of CD133. However, there was a direct correlation between CD133 and CD166 expression levels throughout the entire spectrum of lesions, with higher values for dysplastic lesions. Colocalization of CD133/ CD166 was obvious at the level of cells membranes, with higher coeficients in high grade dysplasia, followed by well and moderate differentiated tumours.Conclusions. CD133/CD166 colocalization is an early event occurring in colon tumorigenesis, with thehighest coeficients recorded for patients with high grade dysplasia, followed by well differentiated tumours. Thus, we consider that the coexpression of these two markers could be useful for further prognostic andtherapeutically stratification of patients with colon cancer.Abbreviations: AJCC - American Joint Committee on Cancer; CCD - charge-coupled device camera sensor; CD133 - prominin-1 (PROM1); CD166 - Activated Leukocyte Cell Adhesion Molecule (ALCAM); CRC - colorectal cancer; CSC - cancer stem cells; DAB - 3,3'-diaminobenzidine chromogen; DAPI - 4',6-diamidino- 2-phenylindole; HE - Hematoxylin and eosin staining; HGD - high grade dysplasia; HRP - horseradish peroxidase; LGD - low grade dysplasia; SDS - sodium dodecyl sulfate*Part of this work has been accepted as a poster presentation at the Digestive Disease Week (DDW) meeting, Chicago, IL, USA May 3-6, 2014

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