Gold Concentration
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Author(s):  
François Turlin ◽  
Stéphane De Souza ◽  
Michel Jébrak ◽  
Pierre-Arthur Groulier ◽  
Jordi Turcotte

The Archean Cheechoo stockwork gold deposit is hosted by a felsic intrusion of tonalitic-granodioritic composition and crosscutting pegmatite dikes in the Eeyou Istchee James Bay area of Quebec, Canada (Archean Superior craton). The evolution of the stockwork is characterized herein using field relationships, vein density, and connectivity measurements on drill core and outcrop zones. The statistical distribution of gold is used to highlight mechanisms of stockwork emplacement and gold mineralization and remobilization. Two statistical populations of gold concentration are present. Population A is represented by gold grades below 1 g/t with a lognormal cumulative frequency. It is widespread in the hydrothermally altered (albite and quartz) and mineralized facies of the pluton. It is controlled by the development of quartz-feldspar-diopside veins as shown by the similar lognormal distribution of grades and vein density and by the correspondence of grades with network connectivity. Diopside and actinolite porphyroblasts in deformed veins within sodic and calcsilicate alteration zones are evidence for auriferous vein emplacement prior to the amphibolite facies peak of metamorphism. Population B (>1 g/t) is erratic and exhibits a strong nugget effect. It is present throughout the mineralized portion of the pluton and in pegmatites. This population is interpreted as the result of gold remobilization during prograde metamorphism and pegmatite emplacement following the metamorphic peak. The pegmatites are interpreted to have scavenged gold emplaced prior to peak metamorphism. These results show the isotropic behavior of the investigated stockwork during regional deformation and its development during the early stages of regional prograde metamorphism.


2021 ◽  
Author(s):  
Priyatha Premnath

Currently fabricated bio-matrices lack important characteristics such as nanometer scale, ‘bumpy’ morphology and an interlinked structure. Therefore, cells cultured on such matrices may not truly represent phenotypes of cells grown in the natural environment. This thesis deals with the synthesis of a three dimensional nanofibrous silicon matrix that is interlinked and possesses a ‘bumpy’ structure that mimics the natural extra cellular matrix. This silicon matrix can be tailored to suit applications of cell proliferation and manipulation. Cell-biomaterial studies show that osteoblasts and fibroblasts proliferated by 300% on three dimensional nanofibrous matrix compared to virgin silicon. To induce controlled cell proliferation, the addition of gold to the silicon matrix was perceived. The phase of gold was altered and combined with silicon forming a unique hybrid structure that prevented the growth of cells in areas of increased gold concentration. Increased gold concentration indicated lower adhesion forces and reduced zeta potentials which consequently lead to decreased cell growth. In addition, the interaction of cancer cells with the three dimensional silicon and gold-silicon hybrid nanofibrous network was studied. Results indicate a 96% reduction in cancer cells compared to virgin silicon. The reduction in cells is attributed to- different phases of silicon and silicon oxides in nanoparticle form, the encapsulation of cells by the nanofibers and apoptosis of cells owing to nanoparticles entering cells passively. To control the growth of cells, silicon surface bio-functionalization was performed to study manipulation of mammalian cells such as fibroblasts as well as cervical and breast cancer cells. The manipulative property is attributed to a mixture of phases of silicon and silicon oxides as well as varied crystal orientations of silicon. It is hypothesized that the mixtures of phases on the substrate alter its surface morphology and consequently induce cell manipulation. Therefore, laser irradiated bio functionalized silicon and its nanostructures are a versatile material for biomedical applications. Based on the process of bio functionalization, both proliferation and cell control and manipulation was achieved in this thesis.


2021 ◽  
Author(s):  
Priyatha Premnath

Currently fabricated bio-matrices lack important characteristics such as nanometer scale, ‘bumpy’ morphology and an interlinked structure. Therefore, cells cultured on such matrices may not truly represent phenotypes of cells grown in the natural environment. This thesis deals with the synthesis of a three dimensional nanofibrous silicon matrix that is interlinked and possesses a ‘bumpy’ structure that mimics the natural extra cellular matrix. This silicon matrix can be tailored to suit applications of cell proliferation and manipulation. Cell-biomaterial studies show that osteoblasts and fibroblasts proliferated by 300% on three dimensional nanofibrous matrix compared to virgin silicon. To induce controlled cell proliferation, the addition of gold to the silicon matrix was perceived. The phase of gold was altered and combined with silicon forming a unique hybrid structure that prevented the growth of cells in areas of increased gold concentration. Increased gold concentration indicated lower adhesion forces and reduced zeta potentials which consequently lead to decreased cell growth. In addition, the interaction of cancer cells with the three dimensional silicon and gold-silicon hybrid nanofibrous network was studied. Results indicate a 96% reduction in cancer cells compared to virgin silicon. The reduction in cells is attributed to- different phases of silicon and silicon oxides in nanoparticle form, the encapsulation of cells by the nanofibers and apoptosis of cells owing to nanoparticles entering cells passively. To control the growth of cells, silicon surface bio-functionalization was performed to study manipulation of mammalian cells such as fibroblasts as well as cervical and breast cancer cells. The manipulative property is attributed to a mixture of phases of silicon and silicon oxides as well as varied crystal orientations of silicon. It is hypothesized that the mixtures of phases on the substrate alter its surface morphology and consequently induce cell manipulation. Therefore, laser irradiated bio functionalized silicon and its nanostructures are a versatile material for biomedical applications. Based on the process of bio functionalization, both proliferation and cell control and manipulation was achieved in this thesis.


Toxics ◽  
2021 ◽  
Vol 9 (5) ◽  
pp. 111
Author(s):  
Maria Mihăilescu ◽  
Adina Negrea ◽  
Mihaela Ciopec ◽  
Petru Negrea ◽  
Narcis Duțeanu ◽  
...  

Gold is one of the precious metals with multiple uses, whose deposits are much smaller than the global production needs. Therefore, extracting maximum gold quantities from industrial diluted solutions is a must. Am-L-GA is a new material, obtained by an Amberlite XAD7-type commercial resin, functionalized through saturation with L-glutamic acid, whose adsorption capacity has been proved to be higher than those of other materials utilized for gold adsorption. In this context, this article presents the results of a factorial design experiment for optimizing the gold recovery from residual solutions resulting from the electronics industry using Am-L-GA. Firstly, the material was characterized using atomic force microscopy (AFM), to emphasize the material’s characteristics, essential for the adsorption quality. Then, the study showed that among the parameters taken into account in the analysis (pH, temperature, initial gold concentration, and contact time), the initial gold concentration in the solution plays a determinant role in the removal process and the contact time has a slightly positive effect, whereas the pH and temperature do not influence the adsorption capacity. The maximum adsorption capacity of 29.27 mg/L was obtained by optimizing the adsorption process, with the control factors having the following values: contact time ~106 min, initial Au(III) concentration of ~164 mg/L, pH = 4, and temperature of 25 °C. It is highlighted that the factorial design method is an excellent instrument to determine the effects of different factors influencing the adsorption process. The method can be applied for any adsorption process if it is necessary to reduce the number of experiments, to diminish the resources or time consumption, or for expanding the investigation domain above the experimental limits.


2021 ◽  
Vol 26 ◽  
pp. 2515690X2110110
Author(s):  
Snehasis Biswas ◽  
Mukesh Chawda ◽  
Kapil Thakur ◽  
Ramacharya Gudi ◽  
Jayesh Bellare

Suvarna Bhasma (SB) is a gold particle-based medicine that is used in Ayurved to treat tuberculosis, arthritis and nervous diseases. Traditionally, the Ayurved preparation processes of SB do exist, but they are all long, tedious and involve several steps. Due to this, there is a possibility of bypassing the necessary Ayurved processes or non-adherence to all steps or use of synthetic gold particles. Our aim is to characterize 5 commercial SB preparations from 5 different manufacturers. A comparative physicochemical, pharmacokinetic (PK) and bioaccumulation study was carried out on all the 5 SB preparations. The general appearance such as color and texture of these 5 samples were different from each other. The size, shape and gold concentration (from 32-98 wt%) varied among all the 5 SBs. The accumulation of ionic gold in zebrafish and gold concentration profiles in rat blood were found to be significantly different for all the 5 SBs. Non-compartmental PK model obtained from the concentration-time profile showed significant differences in various PK parameters such as peak concentration (Cmax), half-life (t1/2) and terminal elimination slope (λz) for all the 5 SB preparations. SB-B showed the highest Cmax (8.55 μg/L), whereas SB-D showed the lowest Cmax (4.66 μg/L). The dissolution of ionic gold from SBs in zebrafish tissue after the oral dose had a 5.5-fold difference between the highest and lowest ionic gold concentrations. All the 5 samples showed distinct physicochemical and biological properties. Based on characteristic microscopic morphology, it was found that 2 preparations among them were suspected of being manufactured by non-adherence to the mentioned Ayurved references.


2020 ◽  
Vol 385 ◽  
pp. 125379 ◽  
Author(s):  
Patrícia Pereira-Silva ◽  
Joel Borges ◽  
Marco S. Rodrigues ◽  
João C. Oliveira ◽  
Eduardo Alves ◽  
...  

2020 ◽  
Vol 26 (10) ◽  
pp. 6-14
Author(s):  
Yu. Pavlenko ◽  

The subject of the research is the methods of forecasting the Eastern Transbaikalia - a large mining region of Russia, in which the main internal and external criteria for ore content are established by modern geological mapping at a scale of 1:1,000,000. The article considers endogenous geochemical criteria for gold concentration in the Earth’s crust of the region, which constitute a mandatory methodological method for predicting gold ore objects at any scale. The aim of the work is to clarify the achieved level of knowledge about the mineralogical and geochemical criteria for gold concentration in the course of the evolution of the Earth’s crust up to the formation of industrial deposits and the isolation of ore formations. The methodology of the study is to systematize a huge amount of factual material concerning the processes of natural concentration of gold, to analyze its representativeness, to assess the completeness and reliability of published and stock information used to clarify the mineralogical and geochemical criteria for predicting ore gold. Using the chemical properties of gold, the forms of finding gold, amount of it in the forming geological complexes and natural environments, their evolution, distribution in structural and tectonic zones, some causes of concentration and mineralogical and geochemical prediction criteria are considered. Special attention is paid to the need to study and account for nanoscale (dispersed) gold. As the main ore-formation units of gold mineralization, standardized ore formations are defined with a division into gold ore proper, complex gold-bearing and gold-bearing and geological and industrial types of deposits. There are 15 geological and industrial types, of which 13 are transbaikal deposits standards and two are attracted from other regions. These types of deposits differ in the number of objects related to them. Due to some similarity in the composition of ore matter, geological and industrial types differ in the most important classification characteristics for the forecast. Areas of distribution of direct and indirect mineralogical and geochemical features grouped into mineralogical and geochemical forecast criteria are promising for endogenous concentration of gold mineralization


Metals ◽  
2019 ◽  
Vol 10 (1) ◽  
pp. 50 ◽  
Author(s):  
Qi Meng ◽  
Guichun Li ◽  
Hua Kang ◽  
Xiaohui Yan ◽  
Huiping Wang ◽  
...  

This paper mainly discusses electrodeposition of gold from iodine leaching solution through single-factor testing and explores the influence of gold concentration in catholyte, mass fraction of iodine in anolyte, anolyte n(I2):n(I−), cell voltage, and electrolysis time on the percentage of gold deposition and coulombic efficiency. Moreover, a response surface methodology was adopted to study interactions among variables and influence on the percentage of gold deposition, with mass fraction of iodine in anolyte, anolyte n(I2):n(I−), and cell voltage as variable factors and percentage of gold deposition as the response value. The electrodeposition process was fitted via pseudo first-order kinetics and pseudo second-order kinetics. Finally, the free surface morphology of gold deposited on the cathode plate was observed by scanning electron microscope. Given the results, a principal effect relationship can be concluded between mass fraction of iodine in anolyte, anolyte n(I2):n(I−), cell voltage, and percentage of gold deposition, with cell voltage > anolyte n(I2):n(I−) > mass fraction of iodine in anolyte and a second-order regression equation obtained with percentage of gold deposition as the response value. The optimized process conditions were gold concentration in catholyte 20 mg/L, mass fraction of iodine in anolyte 0.59%, anolyte n(I2):n(I−) is 1:7.5, cell voltage 12.9 V, and electrolysis time 2 h. The average percentage of gold deposition of three confirmatory experiments was 96.43%, a figure very close to the predicted value of the model 97.76%, which proves that the quadratic polynomial model obtained by response surface methodology optimization is feasible and that the electrodeposition of gold process conforms to a pseudo second-order kinetic model. Au can be attached well to the cathode plate and the deposition layer is formed by granular grain accumulation.


2019 ◽  
Vol 4 (4) ◽  
pp. 501-517
Author(s):  
Raíza De Sousa Batalha ◽  
Elzio Da Silva Barboza ◽  
Carlos Humberto ◽  
Cláudia Do Couto Tokashiki ◽  
Francisco Egídio Cavalcante Pinho ◽  
...  

rocks of the Cuiaba Group, into the inner portion of the Paraguay Belt (Brazil). They occur in a belt (~1200 m) where the host rocks are graphitic phyllites, metadiamictites, metasiltites and sandstones metamorphosed in greenschist facies. In these deposits gold occurs free or included in pyrite related to three types of quartz veins, parallel to Sn (V1), parallel to Sn+1 (V2) and orthogonal (V3) which are rich in gold. The study of outcrops in regional profiles, open mines for gold exploration and drilling holes in the Cangas-Poconé alignment indicate that the preferential location of gold mineralization at (Cangas Facies) is related to the existence of strong lithological control of the mineralizations.The Cangas facies present low permeability of rhythmite, structural arrangement of permeability barriers S0 and S1 at high angle with respect to the fluid migration path and mainly the presence of ferruginous levels acting as geochemical barriers for precipitation of metals in solution in the fluid. The knowledge that gold concentration is related to sedimentary control is important for regional exploration and is a guide for local miners. CONTROLE LITOSTRATIGRÁFICO DOS DEPÓSITOS AURÍFEROS DO LINEAMENTO CANGAS-POCONÉ (CINTURÃO PARAGUAI): IMPLICAÇÕES PARA A EXPLORAÇÃO REGIONAL ResumoOs depósitos de Cangas-Poconé estão hospedados em rochas metassedimentares do Grupo Cuiabá, na porção interna do Cinturão do Paraguai (Brasil). Eles ocorrem em um cinturão (~ 1200 m), onde as rochas hospedeiras são filitos, metadiamictitos, metasiltitos e arenitos grafitados, metamorfoseados em fácies de xisto verde. Nesses depósitos, o ouro ocorre livre ou incluído em pirita relacionada a três tipos de veios de quartzo. O estudo de afloramentos em perfis regionais, minas abertas para exploração de ouro e perfurações no alinhamento Cangas-Poconé indica que a localização preferencial da mineralização de ouro em (Cangas Facies) está relacionada à existência de forte controle litológico.O conhecimento de que a mineralização de ouro está relacionada ao controle sedimentar é importante para a exploração regional e é um guia para os mineradores locais. Palavras-chave: Ouro. Controle Sedimentar. Grupo Cuiabá. Cinturão do Paraguai.


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