scholarly journals Biotechnological Approaches to Facilitate Gold Recovery from Double Refractory Gold Ores

2020 ◽  
Author(s):  
Keiko Sasaki ◽  
Kojo T. Konadu
Keyword(s):  
Solid Phase ◽  
Matter Content ◽  
Gold Recovery ◽  
White Rot ◽  
White Rot Fungus ◽  
Carbonaceous Matter ◽  
Refractory Gold ◽  
Before And After ◽  
Further Development ◽  
Pollutant Gases

Double refractory gold ore (DRGO) not only include ppt levels of gold grains locked in sulfide minerals but also a problematic amount of carbonaceous matter. This causes a significant recovery loss of gold during cyanidation because of the strong affinity of the Au(CN)2 − with the carbonaceous matter. Combustion decreases the carbonaceous matter content, but also emits pollutant gases like CO2, SO2 and As2O3. Therefore, environmentally-friendly solutions have been explored by using biotechnology. Due to the very small amount of the above targets in the ore, it is challenging to show evidential changes in solid-phase before and after the biomineral processing of DRGO. This chapter introduces the mineralogical and chemical changes in the various solid residues produced during a sequential biotreatment, consisting of the liberation of gold from sulfides by an iron-oxidizer and decomposition of carbonaceous matter by lignin-degrading enzymes (lignin peroxidase, manganese peroxidase, laccase) secreted from a white rot-fungus, which successfully improved of gold recovery to over 90%. In addition, further development of biotechnology in the recovery of gold from DRGO is addressed.

scholarly journals Three-Dimensional X-Ray Imaging and Analysis of Fungi on and in Wood

2009 ◽  
Vol 15 (5) ◽  
pp. 395-402 ◽  
Author(s):  
Jan Van den Bulcke ◽  
Matthieu Boone ◽  
Joris Van Acker ◽  
Luc Van Hoorebeke
Keyword(s):  
Three Dimensional ◽  
Three Dimensions ◽  
White Rot ◽  
White Rot Fungus ◽  
Fungal Mycelium ◽  
X Ray ◽  
Fungal Exposure ◽  
X Ray Imaging ◽  
Before And After ◽  
Fundamental Research

AbstractAs wood is prone to fungal degradation, fundamental research is necessary to increase our knowledge aiming at product improvement. Several imaging modalities are capable of visualizing fungi, but the X-ray equipment presented in this article can envisage fungal mycelium in wood nondestructively in three dimensions with submicron resolution. Four types of wood subjected to the action of the white rot fungusCoriolus versicolor(Linnaeus) Quélet (CTB 863 A) were scanned using an X-ray-based approach. Comparison of wood volumes before and after fungal exposure, segmented manually or semiautomatically, showed the presence of the fungal mass on and in the wood samples and therefore demonstrated the usefulness of computed X-ray tomography for mycological and wood research. Further improvements to the experimental setup are necessary to resolve individual hyphae and enhance segmentation.

scholarly journals Flotation of Carbonaceous Matter from a Double Refractory Gold Ore: The Effect of MIBC on Flotation Performance and Kinetics

Minerals ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 1021
Author(s):  
Sugyeong Lee ◽  
Charlotte E. Gibson ◽  
Ahmad Ghahreman
Keyword(s):  
Bubble Size ◽  
Gold Recovery ◽  
Carbonaceous Matter ◽  
Flotation Kinetics ◽  
Pressure Oxidation ◽  
Gold Ore ◽  
Refractory Gold ◽  
Flotation Performance ◽  
Thiosulfate Leaching

The use of alkaline pressure oxidation to pretreat refractory gold ore often results in insufficient gold recovery (<60%) in downstream thiosulfate leaching. To improve gold recovery, flotation was considered for the separation of carbonaceous matter (C-matter). In this study, the effect of MIBC on C-matter flotation was investigated to understand the role of the frother in bubble and froth formation and on flotation kinetics. MIBC dosages between 30 and 150 g/t were used in combination with 500 g/t of kerosene as a collector. The results showed that the recovery and selectivity of C-matter were improved with increasing MIBC dosages. Improved selectivity at higher MIBC dosages was attributed to faster C-matter recovery as bubble size decreased to the critical coalescence concentration (CCC) and to changes to the foam structure. Analysis of flotation kinetics showed that the flotation rate increased as the MIBC dosage increased due to the decreasing bubble size and the reduced induction time caused by the interaction between the collector and the frother. The results of this study explain the role of MIBC in C-matter flotation and can be used as a design basis for scavenger-cleaner flotation testing. Overall, the results show the potential for flotation as a means to improve gold recovery in thiosulfate leaching through the removal of C-matter.

scholarly journals Possibility to Biotransform Anthracyclines by Peroxidases Produced by Bjerkandera adusta CCBAS 930 with Reduction of Geno- and Cytotoxicity and Pro-Oxidative Activity

Molecules ◽  
2021 ◽  
Vol 26 (2) ◽  
pp. 462
Author(s):  
Kamila Rybczyńska-Tkaczyk ◽  
Teresa Korniłłowicz-Kowalska ◽  
Konrad A. Szychowski
Keyword(s):  
Biological Treatment ◽  
Vibrio Fischeri ◽  
Human Fibroblasts ◽  
White Rot ◽  
White Rot Fungus ◽  
Lepidium Sativum ◽  
Anthracycline Antibiotics ◽  
Anthraquinone Dyes ◽  
Before And After ◽  
Lepidium Sativum L

The aim of this study was to evaluate the bioremoval mechanism of anthracycline antibiotics by the white-rot fungus B. adusta CCBAS 930. The activity of oxidoreductases and levels of phenolic compounds and free radicals were determined during the biotransformation of anthraquinone antibiotics: daunomycin (DNR) and doxorubicin (DOX) by B. adusta strain CCBAS 930. Moreover, phytotoxicity (Lepidium sativum L.), ecotoxicity (Vibrio fischeri), genotoxicity and cytotoxicity of anthraquinone dyes were evaluated before and after biological treatment. More than 80% and 90% of DNR and DOX were removed by biodegradation (decolorization). Initial solutions of DNR and DOX were characterized by eco-, phyto-, geno- and cytotoxicity. Despite efficient decolorization, secondary metabolites, toxic to bacteria, formed during biotransformation of anthracycline antibiotics in B. adusta CCBAS 930 cultures. DNR and DOX metabolites did not increase reactive oxygen species (ROS) production in human fibroblasts and resazurin reduction. DNR metabolites did not change caspase-3 activity.

Microbial use of podzol Bh fulvic acids

1969 ◽  
Vol 15 (7) ◽  
pp. 677-680 ◽  
Author(s):  
S. P. Mathur
Keyword(s):  
Soluble Fraction ◽  
Trichoderma Viride ◽  
Phenol Oxidase ◽  
Fulvic Acids ◽  
Sole Source ◽  
Iron Complex ◽  
White Rot ◽  
White Rot Fungus ◽  
Before And After

A Trichoderma viride, a Penicillium frequentons, and an Aspergillus fumigatus were isolated from fulvic acid enrichment cultures. These and a white rot fungus, Poria subacida 17780, were tested for their ability to decompose fulvic acids (FA) in liquid cultures. All of the organisms tested were totally inhibited by the presence of FA at 1% concentration. The soil isolates brought about transformation of the FA to humic acids. In 48 h, the Poria subacida used 66% of the FA (0.05%) present as the sole source of carbon in static replacement culture, and up to 45% in 24 days in a static culture. Loss of FA was measured by photometry and confirmed by determination of the carbon content of FA precipitated as iron complex before and after attack. Phenol oxidase of the Poria subacida apparently had no role in degradation of the FA but could darken the color of a well-aerated medium through oxidative transformation of FA products.Preliminary studies with cell-free preparations of the P. subacida indicated that the breakdown is initiated by an enzyme present in particulate fraction of the cells and this activity is extended or facilitated by a factor present in the soluble fraction of the cells. FA-cleaving enzymes(s) may thus be available for use in controlled FA degradation studies aimed at characterizing soil humus.

scholarly journals The use of Phanerochaete chrysosporium for modification of bentonite for preconcentration and determination of heavy metals

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Sevgi Kocaoba ◽  
Mehtap Duman Parlak ◽  
Munevver Arisoy
Keyword(s):  
Metal Ions ◽  
Phanerochaete Chrysosporium ◽  
Solid Phase ◽  
Atomic Absorption Spectrophotometry ◽  
Sample Volume ◽  
White Rot ◽  
White Rot Fungus ◽  
Sorption Data ◽  
Metal Biosorption

AbstractIn this study, a solid phase extraction method was successfully applied in the preconcentration and determination of trace levels of Cu(II) and Cd(II) ions and Phanerochaete chrysosporium (white rot fungus) modified bentonite was used as adsorbent. After the biosorption of Cu(II) and Cd(II) ions, metal concentrations in the samples were determined by atomic absorption spectrophotometry. pH, adsorbent amount, eluent type, sample volume, and flow rate, which are effective in the adsorption of metal ions, have been studied. 1 M HCl was used for desorption of these metal ions retained (recovery 95–100%). In addition, the effect of interfered ions has also been investigated. Sorption data were examined according to Langmuir and Freundlich adsorption equations. The results obtained show that the applied method has a high metal biosorption capacity, and Cu(II) and Cd(II) ions are successfully recovered. It was also successful in applying the proposed enrichment method to real water samples.Recovery values between 92.3% and 97.3% were obtained for the studied metal ions. According to the results, the proposed method can be successfully applied to water analysis at 95% confidence interval.

scholarly journals Significance of Acid Washing after Biooxidation of Sulfides in Sequential Biotreatment of Double Refractory Gold Ore from the Syama Mine, Mali

Minerals ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 1316
Author(s):  
Cindy Cindy ◽  
Ryotaro Sakai ◽  
Diego M. Mendoza ◽  
Kojo T. Konadu ◽  
Keiko Sasaki
Keyword(s):  
Gold Recovery ◽  
Carbonaceous Matter ◽  
Acid Attack ◽  
Gold Ores ◽  
Gold Ore ◽  
Positive Effects ◽  
Acid Washing ◽  
Washing Process ◽  
Refractory Gold ◽  
Mineralogical Compositions

Environmentally friendly pretreatment of double refractory gold ores (DRGO) to improve gold recovery without emitting pollutant gas is challenging. Sequential biotreatment, including iron-oxidizing microorganisms to decompose sulfides, followed by the enzymatic decomposition of carbonaceous matter, was recently developed. The effect of acid washing by 1 M HCl for 24 h between two bioprocesses was evaluated using a real double refractory gold ore from the Syama mines, Mali, which includes 24 g/t of Au and 5.27 wt % of carbon with a relatively higher graphitic degree. The addition of the acid washing process significantly improved gold recovery by cyanidation to yield to 84.9 ± 0.7% from 64.4 ± 9.2% (n = 2). The positive effects of acid washing can be explained by chemical alteration of carbonaceous matter to facilitate the accessibility for lignin peroxidase (LiP) and manganese peroxidase (MnP) in cell-free spent medium (CFSM), although the agglomeration was enhanced by an acid attack to structural Fe(III) in clay minerals. Sequential treatment of DRGO basically consists of the oxidative dissolution of sulfides and the degradation of carbonaceous matter prior to the extraction of gold; however, the details should be modified depending on the elemental and mineralogical compositions and the graphitic degree of carbonaceous matter.

scholarly journals Cutlink Cleaning Head with a Spreading Feature for Biological Sprout Control

2021 ◽  
Vol 43 (1) ◽  
Author(s):  
Leena Hamberg ◽  
Markus Strandström ◽  
Timo Saksa
Keyword(s):  
Norway Spruce ◽  
White Rot ◽  
White Rot Fungus ◽  
Fungal Treatment ◽  
Stand Management ◽  
Young Stand ◽  
Downy Birch ◽  
Young Forests ◽  
Further Development ◽  
Potential Tool

The ability of deciduous trees to sprout efficiently after cutting is problematic in young forests where the target is to cultivate coniferous trees for industry. Since the use of chemicals has been restricted, new alternatives are needed. One potential and environmentally friendly option is biological sprout control that is based on the use of a white-rot fungus, Chondrostereum purpureum (Pers. Ex Fr.) Pouzar. This method has been efficient in earlier investigations when performed manually, but efficient, fully mechanized devices which are able to cut and treat stumps with a fungus are still unavailable. Therefore, the efficacy of biological sprout control conducted with a Cutlink cleaning head equipped with a spreading feature was studied in two young Norway spruce (Picea abies (L.) H. Karst.) forests in central Finland.Sample plots for the control (cutting deciduous saplings only) and fungal treatment (cutting and spreading fungal inoculum on fresh stump surfaces) were established, and the ability of the Cutlink cleaning head in preventing sprouting of silver and downy birch (Betula pendula Roth and B. pubescens Ehrh., respectively) in the sample plots was investigated for two years.In the near vicinity of cultivated Norway spruce, the proportion of cut deciduous saplings varied from 50–60% after the Cutlink operation. The average mortality of silver and downy birch stumps in the fungal treatment plots was ca. 40%, while stump mortality in the control, i.e., cutting only, was only ca. 13%, after two years. Stump mortality increased up to 73% if the stumps did not include old branches, i.e., the stump was cut to a low enough height.These results confirmed that the Cutlink cleaning head is a potential tool in young stand management operation but further development will be needed in working methods in order to achieve lower stump heights (no branches on the stump) and also to increase the proportion of cut saplings.

The stability of dislocation networks under various oxygen-doping conditions in superconducting Bi2Sr2CaCu2Oy single crystals and their influence on the flux pinning properties

1994 ◽  
Vol 52 ◽  
pp. 802-803
Author(s):  
Y. Feng ◽  
X. Y. Cai ◽  
R. J. Kelley ◽  
D. C. Larbalestier
Keyword(s):  
Single Crystals ◽  
Oxygen Content ◽  
Basal Plane ◽  
Flux Pinning ◽  
Pinning Centers ◽  
Before And After ◽  
Anomalous Peak ◽  
Basal Plane Dislocation ◽  
The Stability ◽  
Further Development

The issue of strong flux pinning is crucial to the further development of high critical current density Bi-Sr-Ca-Cu-O (BSCCO) superconductors in conductor-like applications, yet the pinning mechanisms are still much debated. Anomalous peaks in the M-H (magnetization vs. magnetic field) loops are commonly observed in Bi2Sr2CaCu2Oy (Bi-2212) single crystals. Oxygen vacancies may be effective flux pinning centers in BSCCO, as has been found in YBCO. However, it has also been proposed that basal-plane dislocation networks also act as effective pinning centers. Yang et al. proposed that the characteristic scale of the basal-plane dislocation networksmay strongly depend on oxygen content and the anomalous peak in the M-H loop at ˜20-30K may be due tothe flux pinning of decoupled two-dimensional pancake vortices by the dislocation networks. In light of this, we have performed an insitu observation on the dislocation networks precisely at the same region before and after annealing in air, vacuumand oxygen, in order to verify whether the dislocation networks change with varying oxygen content Inall cases, we have not found any noticeable changes in dislocation structure, regardless of the drastic changes in Tc and the anomalous magnetization. Therefore, it does not appear that the anomalous peak in the M-H loops is controlled by the basal-plane dislocation networks.

ANALYSIS OF RADIOIMMUNOASSAY BY DISC ELECTROPHORESIS AND SUCROSE GRADIENT CENTRIFUGATION

1971 ◽  
Vol 66 (2) ◽  
pp. 257-265 ◽  
Author(s):  
Lubomir Valenta ◽  
Michel L. Aubert
Keyword(s):  
Sucrose Gradient ◽  
Solid Phase ◽  
Gradient Centrifugation ◽  
Human Growth ◽  
Disc Electrophoresis ◽  
Separate Analysis ◽  
Adrenocorticotrophic Hormone ◽  
Sucrose Gradient Centrifugation ◽  
Before And After ◽  
Polypeptide Hormones

ABSTRACT Radioiodine-labelled synthetic adrenocorticotrophic hormone (ACTH), human growth hormone (HGH), human chorionic somato-mammotrophin (HCS), and human (HTSH) and bovine (BTSH) thyroid stimulating hormones were studied by disc-electrophoresis and sucrose gradient centrifugation before and after incubation with corresponding antisera. All antisera contained 7 S antibodies. After incubation, soluble antigenantibody complexes besides a small amount of precipitate were observed in the incubation mixture, characteristic of each hormone. The complexes migrated like gamma globulins or more slowly on disc-electrophoresis. and on sucrose gradient centrifugation showed patterns dependent on the time of incubation. Light 7 or 9 S, or < 12 S complexes occurred mostly after incubation for several minutes (up to 30 min) before analysis. When incubation was prolonged to 24 h and more, these relatively light complexes disappeared or diminished in favour of heavier soluble or precipitating complexes. Reproducibly obtainable sedimentation patterns of the soluble complexes suggested some definite recombination of antigen molecules with 7 S antibodies. The complexes did not occur on incubation with other sera than an antiserum to a given hormone. They were not influenced by EDTA. Displacement of the radioactivity of the complexes into the free hormone peak was obtained by addition of a non-labelled hormone identical with the labelled one. Sucrose gradient centrifugation and disc-electrophoresis are recommended for the study of immunoreaction of diluted materials and for a separate analysis of different steps of the radioimmunoassay. Radioimmunoassay was introduced for the measurement of protein hormones by Yalow & Berson (1960). The method, described originally for insulin, was later adapted to the detection of a number of protein and polypeptide hormones. On incubation of the hormone with its antiserum, a soluble antigenantibody complex is formed, which is separated from an excess of the free hormone by various methods, e. g. chromatoelectrophoresis, precipitation with a second antibody, adsorption on a solid phase etc. (Hunter 1967). Sucrose gradient centrifugation and disc-electrophoresis were occasionally used to follow some isolated aspect of radioimmunoassay (Fitschen 1965; Monjardino et al. 1968). We are demonstrating that these methods made it possible to analyze the radioimmunoassay step by step and thus may be useful for practical purposes as well as in a study of the immunoreaction of diluted materials.

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