Chemical Oxidative Kinetic Study of Arsenopyrite Dissolved by Iron Solution

To extract the Au efficiently, the kinetic experiments were performed in a 1000 mL-glass bulbs which were made by us to determine the oxidative dissolution of arsenopyrite by iron solution. The results show that the rate of dissolution of arsenopyrite increases with the increasing of temperature from 30 degrees C to 75 degrees C, in which an apparent activation energy for arsenopyrite oxidation is 10.850 kJ.mol(-1). Moreover, the rate of oxidative dissolution of arsenopyrite increases with the increasing of concentration of ferric iron with the reaction order is 0.34 (4.62 similar to 40.04 g.L-1) and 0.61 (27.32 similar to 36.33 g.L-1). In contrast, the reduction of hydrogen ion can promote concentration promotes the leaching rate of arsenopyrite with the reaction order of -0.29

Why Zijinshan copper bioheapleaching plant works efficiently at low microbial activity - Study on leaching kinetics of copper sulfides and its implications

Zijinshan commercial bioheapleaching-SX-EW plant has been in operation since December 2005. 13.9 million tonnes of low grade copper sulfide ore (Cu 0.38%) has been leached efficiently with an annual recovery of 80% in this distinct leaching system with high iron concentration, high temperature, high acidity and low microbial activity. This paper is to study the key factors which influence the heap operation in Zijinshan. Dissolution kinetics of diginite and covellite was carried out in acid ferric sulfate solution under controlled redox potential. Moreover, column bioleaching tests were conducted in the laboratory with raffinate from the plant. Both results showed that the main factors accelerating dissolution rate of Cu1.8S/CuS were mainly temperature and ferric concentration, while redox potential only had a slight positive effect. The present work provides an insight into mineral kinetics to understand this unique bioheapleaching operation and gives further information for optimization of the existing practices. (c) 2013 Elsevier Ltd. All rights reserved

Impacts of solar UV radiation on grazing, lipids oxidation and survival of Acartia pacifica Steuer (Copepod)

UV radiation is known to affect aquatic primary producers and their grazers. However, little has been documented on its effects on zooplankton grazing. In this study, the authors investigated the effects of photosynthetically active radiation (PAR, 400-700 nm), ultraviolet-A (UV-A, 320-400 nm) and ultraviolet-B (UV-B, 280-320 nm) radiation on grazing, mortality and lipids oxidation of the copepod Acartia pacifica collected from the Xiamen Bay. After 30 min of the exposures, the copepod was fed in darkness with the diatom Phaeodactylum tricornutum at two cell concentrations (2.5x10(4) and 2.5x10(5) cells/ml). At the low cell concentration, the individuals pre-exposed to PAR (218.0 W/m(2))+UV-A (48.2 W/m(2)) or PAR+UV-A+UV-B (2.1 W/m(2)) showed suppressed clearance and grazing activities compared with those receiving PAR alone, by 22.7% and 17.1% for clearance and by 22.6% and 5.5% for grazing rates, respectively. However, the suppression on clearance and grazing became indistinctive at the high food concentration. Exposures to UV-A and UV-B led to increased lipid oxidation and higher mortality, furthermore, the mortality linearly increased with enhanced oxidation of lipid.Changjiang Scholars and Innovative Research Team Program [IRT0941]; Shanghai Municipal Natural Science Foundation [11ZR1449900]; Visiting Scholarship of State Key Laboratory of Marine Environmental Science, Xiamen University [MELRS0919

The complete mitochondrial genome of brown algae: Sargassum fusiforme (Harvey) Setchell

We describe the complete mitochondrial genome sequence of Sargassum fusiforme. This mitogenome is a circular molecule of 34,695 bp in length and had an overall GC content of 37.54%%. Gene annotation showed that 35 protein-coding genes, 2 open reading frames, 25 transfer RNA genes, and 3 ribosomal RNA genes. The phylogenetic tree based on Bayesian shows that S. fusiforme belongs to genus Sargassum, support current taxonomic systems

Column leaching of low-grade sulfide ore from Zijinshan copper mine

Copper and iron dissolution of Zijinshan low-grade copper sulfide ores was investigated in ore-packed columns. At 60 degrees C and pH 1.0, 37.1 g Fe(III) L-1 permitted effective copper dissolution and inhibited the activity of iron-oxidizing microorganisms. At 30 degrees C, microorganisms stimulated Fe(II) and pyrite oxidation, resulting in 85 and 54% of copper and pyrite extraction yields, respectively. Bacteria belonging to the genera Acidithiobacillus and Leptospirillum were dominant as observed by real-time PCR assay. Aeration and inoculation of columns were not necessary. Solutions had a higher pH of 1.7 in the columns operated without recirculation. Under these conditions, copper extraction was not affected and Fe(III) precipitated as jarosite, indicating a novel method for iron control in Zijinshan copper mine. (c) 2015 Elsevier B.V. All rights reserved

The complete chloroplast genome of Sargassum fusiforme

The complete chloroplast genome sequence of Sargassum fusiforme is presented here. Circular mapping revealed that the complete chloroplast DNA sequence of S. fusiforme was 124,298 bp in length and had an overall AT content of 69.57%, including 137 protein-coding genes, 2 open reading frames, 28 transfer RNA genes, and 6 ribosomal RNA genes. The phylogenetic tree based on Bayesian shows that all kinds of Phaeophyceae were clustered into two monophyletic groups