Microbial & Mineralogical Dynamics during Copper Sulfides Bioleaching, the Search for the Missing Link

2015 ◽  
Vol 1130 ◽  
pp. 131-135
Author(s):  
Roberto A. Bobadilla-Fazzini ◽  
Patricia Piña ◽  
Veronica Gautier ◽  
Karen Brunel ◽  
Pilar Parada
Keyword(s):  
Dynamic Process ◽  
Copper Sulfide ◽  
Pure Copper ◽  
Copper Recovery ◽  
Process Conditions ◽  
Secondary Phases ◽  
Microbial Dynamics ◽  
Copper Sulfides ◽  
The One ◽  
Kinetics Of

Bioleaching involves a chemical-microbial-driven dynamic process of oxidation and dissolution, as well as precipitation and formation of surface secondary phases that change the copper sulfide exposure/occlusion profiles. This dynamic process determines the kinetics of copper sulfides bioleaching. Former studies have shown the microbiological dynamics of the leaching solutions, and most mineralogical studies have been done with pure copper sulfide species under controlled conditions. In this work we aim to unravel the link between the microbiology and the mineralogy during the bioleaching of a mainly primary copper sulfide ore through the determination of the surface microbial and mineralogical variations in time applying process conditions. The results showed that the microbial dynamics in the leaching solutions is not representative of the bioleaching process since it differs significantly from the one established at the ore surface. Moreover, a major and fast alteration of the primary copper sulfide minerals chalcopyrite (CuFeS2) and bornite (Cu5FeS4) was observed, having as the major bioleaching intermediate the formation of covellite (CuS). When the ore was subjected to a mesophilic inoculation, the microbial dynamics was modified, significantly changing the mineralogical dynamics of these primary sulfides and enhancing the overall kinetics of copper recovery.

A Study of the Optimal Model of the Flotation Kinetics of Copper Slag from Copper Mine BOR

2014 ◽  
Vol 59 (3) ◽  
pp. 821-834 ◽  
Author(s):  
Rodoljub D. Stanojlović ◽  
Jovica M. Sokolović
Keyword(s):  
Pure Copper ◽  
Copper Slag ◽  
Copper Recovery ◽  
Optimal Model ◽  
Flotation Kinetics ◽  
Kinetics Parameters ◽  
Flotation Tailings ◽  
Copper Mine ◽  
Flotation Cell ◽  
Kinetics Of

Abstract In this study the effect of mixtures of copper slag and flotation tailings from copper mine Bor, Serbia on the flotation results of copper recovery and flotation kinetics parameters in a batch flotation cell has been investigated. By simultaneous adding old flotation tailings in the ball mill at the rate of 9%, it is possible to increase copper recovery for about 20%. These results are compared with obtained copper recovery of pure copper slag. The results of batch flotation test were fitted by MatLab software for modeling the first-order flotation kinetics in order to determine kinetics parameters and define an optimal model of the flotation kinetics. Six kinetic models are tested on the batch flotation copper recovery against flotation time. All models showed good correlation, however the modified Kelsall model provided the best fit.

Mineralogical Dynamics of Primary Copper Sulfides Mediated by Acidophilic Biofilm Formation

2017 ◽  
Vol 262 ◽  
pp. 325-329 ◽  
Author(s):  
Roberto A. Bobadilla-Fazzini
Keyword(s):  
Biofilm Formation ◽  
Copper Recovery ◽  
Process Conditions ◽  
Mineral Surface ◽  
Flow Conditions ◽  
Mineralogical Analysis ◽  
Acidophilic Microorganisms ◽  
Copper Sulfides ◽  
New Process ◽  
Sulfur Oxidizing

Bioleaching of copper sulfides is catalyzed by iron-and sulfur-oxidizing acidophilic microorganisms attached to the mineral surface forming a biofilm. However, the link between copper sulfides bioleaching and biofilm formation is not yet fully understood. Understanding the factors that are limiting the bioleaching kinetics for different copper sulfide minerals through exhaustive mineralogical analysis of the mineral surface with concomitant biofilm formation during the leaching process will deliver new process conditions with enhanced kinetics and higher copper recovery. In this work we have developed and standardized a reproducible flow cell method able to mimic heap/dump bioleaching laminar flow conditions to study the mineralogical dynamics by advanced mineralogical analysis including QEMSCAN and SEM-EDS coupled to biofilm formation analysis. Based on this method, the bioleaching mineralogical dynamics of primary copper sulfides (enargite (Cu3AsS4), chalcopyrite (CuFeS2) and bornite (Cu5FeS4)) have been determined in the presence of biofilm formation. Supported by the observed mineralogical dynamics, different mechanisms of dissolution for bioleaching were observed as well as selective biofilm formation over the mineral surface, showing enhanced conditions for copper recovery.

Arrangement Of Monomeric Units In Fibrin

1979 ◽  
Author(s):  
Jan Hermans
Keyword(s):  
Fiber Axis ◽  
High Symmetry ◽  
Linear Polymers ◽  
Fiber Volume ◽  
High Fiber ◽  
Rotation Axes ◽  
Small Set ◽  
Helical Turn ◽  
The One ◽  
Kinetics Of

Measurements of light scattering have given much information about formation and properties of fibrin. These studies have determined mass-length ratio of linear polymers (protofibrils) and of fibers, kinetics of polymerization and of lateral association and volume-mass ratio of thick fibers. This ratio is 5 to 1. On the one hand, this high value suggests that the fiber contains channels that allow the diffusion of enzymes such as Factor XHIa and plasmin; on the other hand, the high value appears paradoxical for a stiff fiber made up of elongated units (fibrin monomers) arranged in parallel. Such a high fiber volume is a property of only a small set out of many high-symmetry models of fibrin, which may be constructed from overlapping three-domain monomers which are arranged into strands, are aligned nearly parallel to the fiber axis and make adequate longitudinal and lateral contacts. These models contain helical protofibrils related to each other by rotation axes parallel to the fiber axis. The protofibrils may contain 2, 3 or 4 monomers per helical turn and there are four possible symmetries. A large specific volume is achieved if the ends of each monomer are slightly displaced from the protofibril axis, either by a shift or by a tilt of the monomer. The fiber containing tilted monomers is more highly interconnected; the two ends of a tilted monomer form lateral contacts with different adjacent protofibrils, whereas the two ends of a non-tilted monomer contact the same adjacent protofibril(s).

scholarly journals Synthesis and Polymerization Kinetics of Rigid Tricyanate Ester

Polymers ◽  
2021 ◽  
Vol 13 (11) ◽  
pp. 1686
Author(s):  
Andrey Galukhin ◽  
Roman Nosov ◽  
Ilya Nikolaev ◽  
Elena Melnikova ◽  
Daut Islamov ◽  
...  
Keyword(s):  
Kinetic Analysis ◽  
Single Step ◽  
Polymerization Kinetics ◽  
Scanning Calorimetry ◽  
Modulated Differential Scanning Calorimetry ◽  
Diffusion Controlled ◽  
Polymerization Product ◽  
The One ◽  
Kinetics Of

A new rigid tricyanate ester consisting of seven conjugated aromatic units is synthesized, and its structure is confirmed by X-ray analysis. This ester undergoes thermally stimulated polymerization in a liquid state. Conventional and temperature-modulated differential scanning calorimetry techniques are employed to study the polymerization kinetics. A transition of polymerization from a kinetic- to a diffusion-controlled regime is detected. Kinetic analysis is performed by combining isoconversional and model-based computations. It demonstrates that polymerization in the kinetically controlled regime of the present monomer can be described as a quasi-single-step, auto-catalytic, process. The diffusion contribution is parameterized by the Fournier model. Kinetic analysis is complemented by characterization of thermal properties of the corresponding polymerization product by means of thermogravimetric and thermomechanical analyses. Overall, the obtained experimental results are consistent with our hypothesis about the relation between the rigidity and functionality of the cyanate ester monomer, on the one hand, and its reactivity and glass transition temperature of the corresponding polymer, on the other hand.

scholarly journals Kinetics of drying of basil leaves (Ocimum basilicum L.) in the infrared

2012 ◽  
Vol 16 (12) ◽  
pp. 1346-1352 ◽  
Author(s):  
Renata C. dos Reis ◽  
Ivano A. Devilla ◽  
Diego P. R. Ascheri ◽  
Ana C. O. Servulo ◽  
Athina B. M. Souza
Keyword(s):  
Experimental Data ◽  
Ocimum Basilicum ◽  
Coefficient Of Determination ◽  
Chisquare Test ◽  
The Mean ◽  
Drying Curves ◽  
The One ◽  
Increasing Temperature ◽  
Air Circulation ◽  
Kinetics Of

The objective of this paper was to model the drying curves of the leaves of basil (Ocimum basilicum L.) in the infrared at temperatures of 50, 60, 70 and 80 ºC and to evaluate the influence of drying temperature on the color of dried leaves. Drying was conducted in infrared dryer with temperature and greenhouse air circulation. Experimental data were fitted to eight mathematical models. The magnitude of the coefficient of determination (R²), the mean relative error (P), the estimated mean error (SE) and chisquare test (χ2) were used to verify the degree of fitness of the models. From the study it was concluded that: a) the behavior of the drying curves of basil leaves was similar to most agricultural products, the drying times in the infrared were less than the drying times in an oven with air circulation, b) the mathematical drying model proposed by Midilli et al. (2002) was the one which best adjusted to the experimental data, c) the diffusion coefficient ranged from 9.10 x 10-12 to 2.92 x 10-11 m² s-1 and d) the color of the samples was highly influenced by drying, becoming darker due to loss of chlorophyll with increasing temperature.

Oxidation of Copper Sulfides in Aqueous Ammonia. III. Kinetic Characteristics

1979 ◽  
Vol 32 (12) ◽  
pp. 2597 ◽  
Author(s):  
AO Filmer ◽  
AJ Parker ◽  
BW Clare ◽  
LGB Wadley
Keyword(s):  
Aqueous Ammonia ◽  
Sulfide Oxidation ◽  
Metal Sulfide ◽  
Diffusion Control ◽  
Sulfate Ions ◽  
Kinetics Of Oxidation ◽  
Copper Sulfides ◽  
Shrinking Core ◽  
Kinetics Of ◽  
And Diffusion

The kinetics of oxidation with oxygen of chalcocite, Cu2S, to CuS in buffered aqueous ammonia at pH 10.5 at 30� can be modeled approximately by a shrinking core of Cu2S within a thickening shell of CuxS (x ≥ 1). The Cu2S core offers partial cathodic protection to the CuxS and diffusion of Cu+ through CuxS controls the rate of reaction. The kinetics of oxidation of covellite, CuS, to Cu2+, sulfur and sulfate ions in the same solvent can be modeled by a shrinking core of CuS surrounded by a shrinking sphere of CuyS (y < 1) which is much less effectively protected cathodically by the CuS core. Oxidation of CuS is subject to mixed chemical and diffusion control. Rates of oxidation of NiS and of CuS, in the presence and absence of tetrachloroethene and ammonium sulfate, show that, whether sulfur is a major oxidation product or not, the presence of sulfur has very little, if any, influence on the rate or mechanism of oxidation. This is contrary to current ideas on metal sulfide oxidation.

Effect of Nonionic Surfactants on the Kinetics of Disproportion of Copper Sulfide Nanoparticles in the Aqueous Sols

2001 ◽  
Vol 13 (5) ◽  
pp. 1789-1793 ◽  
Author(s):  
Roshan H. Kore ◽  
Jaideep S. Kulkarni ◽  
Santosh K. Haram
Keyword(s):  
Copper Sulfide ◽  
Nonionic Surfactants ◽  
Kinetics Of

Kinetics of Water and Chloride Exchanges During Adaptation of the European Eel to Sea Water

1973 ◽  
Vol 58 (1) ◽  
pp. 105-121
Author(s):  
R. KIRSCH ◽  
N. MAYER-GOSTAN
Keyword(s):  
Fresh Water ◽  
Sea Water ◽  
Anguilla Anguilla ◽  
Maximum Level ◽  
Progressive Increase ◽  
Plasma Sodium ◽  
European Eel ◽  
Drinking Rate ◽  
The One ◽  
Kinetics Of

Using isotopic procedures, the drinking rate and chloride exchanges were studied in the eel Anguilla anguilla during transfer from fresh water to sea water. 1. Following transfer to sea water there is a threefold increase of the drinking rate (lasting about 1 h). Then it falls to a minimum after 12-16 h and rises again to a maximum level about the seventh day after the transfer. Then a gradual reduction leads to a steady value which is not significantly different from the one observed in fresh water. 2. The changes with time of the plasma sodium and chloride concentrations are given. Their kinetics are not completely alike. 3. The chloride outflux increases 40-fold on transfer of the eel to sea water, but even so it is very low. After the sixth hour in sea water there is a progressive increase in the flux, so that on the fourth day it is higher (500 µ-equiv. h-1.100 g-1) than in the seawater-adapted animals (230 µ-equiv.h-1.100 g-1). 4. Drinking rate values in adapted animals are discussed in relation to the external medium. The kinetics of the drinking rate together with variations in body weights after freshwater-seawater transfer are discussed in relation to the possible stimulus of the drinking reflex. 5. Chloride fluxes (outflux, net flux, digestive entry) are compared and lead one to assume that in seawater-adapted fish one-third of the chloride influx enters via the gut and two-thirds via the gills.

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