Processing of gold-antimony concentrates

This paper describes the results of a study that looked at processing of goldantimony concentrates with selective extraction of antimony and gold as commodities. The common global practice of processing antimony sulphide concentrates (20–30% Sb) is based on alkaline sulphide leaching followed by precipitation of metallic antimony by electrowinning. However, application of this technique to process sulphide concentrates that, apart from antimony, also contain gold, can be difficult as, together with antimony, up to 10–15% of gold can leach to the solution. It takes a special process during final refining of cathode antimony to recover that gold. This paper describes a process that involves two stages of atmospheric leaching of antimony. The gold that leached to the solution is precipitated with zinc after the first stage of antimony leaching. Together with atmospheric leach tailings, it then goes to the pressure oxidation unit. This process helps oxidize the rest of the sulphides and release refractory gold. The resultant cake is processed following a standard sorption cyanidation technique. The paper looks at the antimony leaching rate and the rate at which gold leaches to the solution during this process. The paper describes the results of selective precipitation of gold from gold-antimony solutions and highlights certain features of this process. A series of tests was conducted to test the techniques of pressure oxidation of atmospheric leach tailings and cyanidation of the residue. The paper also describes a process that was developed for processing of goldantimony concentrates and precipitation of antimony and gold. An antimony recovery exceeding 90–95% can be achieved when using this process. At the same time, the percent of dissolved gold can be reduced from 10–15 tо 1–3%.

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Efficient common objects localization based on deep hybrid Siamese network

Journal of Intelligent & Fuzzy Systems ◽

10.3233/jifs-210854 ◽

2021 ◽

pp. 1-10

Author(s):

Mona M. Moussa ◽

Rasha Shoitan ◽

Mohamed S. Abdallah

Keyword(s):

Distance Matrix ◽

Multiple Objects ◽

Siamese Network ◽

Generation Stage ◽

Pascal Voc ◽

The Common ◽

Conventional Methods ◽

Weakly Supervised ◽

Bounding Boxes ◽

Two Stages

Finding the common objects in a set of images is considered one of the recent challenges in different computer vision tasks. Most of the conventional methods have proposed unsupervised and weakly supervised co-localization methods to find the common objects; however, these methods require producing a huge amount of region proposals. This paper tackles this problem by exploiting supervised learning benefits to localize the common object in a set of unlabeled images containing multiple objects or with no common objects. Two stages are proposed to localize the common objects: the candidate box generation stage and the matching and clustering stage. In the candidate box generation stage, the objects are localized and surrounded by the bounding boxes. The matching and clustering stage is applied on the generated bounding boxes and creates a distance matrix based on a trained Siamese network to reflect the matching percentage. Hierarchical clustering uses the generated distance matrix to find the common objects and create clusters for each one. The proposed method is trained on PASCAL VOC 2007 dataset; on the other hand, it is assessed by applying different experiments on PASCAL VOC 2007 6×2 and Object Discovery datasets, respectively. The results reveal that the proposed method outperforms the conventional methods by 8% to 40% in terms of corloc metric.

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ANALYTICAL SOLUTION OF THE FREQUENCY OF THE LOAD OSCILLATION AT AN ARBITRARY GIRDER NODE IN THE SYSTEM MAPLE

Stroitel stvo nauka i obrazovanie [Construction Science and Education] ◽

10.22227/2305-5502.2018.4.3 ◽

2019 ◽

pp. 3-3

Author(s):

Mikhail N. Kirsanov ◽

Dmitriy V. Tinkov

Keyword(s):

Analytical Solution ◽

Arbitrary Number ◽

Analytical Form ◽

Labor Costs ◽

Induction Method ◽

Regular Type ◽

Final Formula ◽

The Common ◽

Two Stages ◽

Elastic Lattice

Introduction. We study the oscillations of a massive load on a planar statically definable symmetric truss of a regular type with parallel belts. Truss weight is not included. Free vertical oscillations are considered. The stiffness of the truss rods is assumed to be the same, the deformations are elastic. Lattice of the truss is double with descending braces and racks. New in the formulation and solution of the problem is the analytical form of the solution, which makes it possible in practice to easily evaluate the frequency characteristics of the structure depending on an arbitrary number of truss panels and the location of the load. Materials and methods. The operators and methods of the system of computer mathematics Maple are used. To determine the forces in the rods, the knotting method is used. The common terms of the sequence of coefficients of solutions for different numbers of panels are obtained from solving linear homogeneous recurrent equations of various order, obtained by special operators of the Maple system. Dependence on two arbitrary natural parameters is revealed in two stages. First, solutions for fixed load positions are found, then these solutions are summarized into one final formula for frequency. Results. By a series of individual solutions to the problem of load oscillation using the double induction method, it was possible to find common members of all sequences. The solution is polynomial in both natural parameters. Graphs constructed for particular cases, showed the adequacy of the approach. The discontinuous non-monotonic nature of the intermittent change depending on the number of truss panels and some other features of the solution are noted. Conclusions. It is shown that the induction method, previously applicable mainly to statics problems with one parameter (number of truss panels), is fully operational to the problems of the oscillations of system with two natural parameters. It should be noted that significant labor costs and a significant increase in the time symbolic transformations in such tasks

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Basic iron sulfate — a potential killer in the processing of refractory gold concentrates by pressure oxidation

Mining Metallurgy & Exploration ◽

10.1007/bf03402383 ◽

2010 ◽

Vol 27 (2) ◽

pp. 81-88 ◽

Cited By ~ 2

Author(s):

C. A. Fleming

Keyword(s):

Iron Sulfate ◽

Pressure Oxidation ◽

Refractory Gold

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Process simulation and gate-to-gate life cycle assessment of hydrometallurgical refractory gold concentrate processing

The International Journal of Life Cycle Assessment ◽

10.1007/s11367-019-01723-6 ◽

2019 ◽

Vol 25 (3) ◽

pp. 456-477 ◽

Cited By ~ 1

Author(s):

Heini Elomaa ◽

Pia Sinisalo ◽

Lotta Rintala ◽

Jari Aromaa ◽

Mari Lundström

Keyword(s):

Global Warming ◽

Life Cycle Assessment ◽

Life Cycle ◽

Environmental Impacts ◽

Process Simulation ◽

Development Stage ◽

Environmental Indicators ◽

Gold Recovery ◽

Pressure Oxidation ◽

Refractory Gold

Abstract Purpose Currently, almost all cyanide-free gold leaching processes are still in the development stage. Proactively investigating their environmental impacts prior to commercialization is of utmost importance. In this study, a detailed refractory gold concentrate process simulation with mass and energy balance was built for state-of-the-art technology with (i) pressure oxidation followed by cyanidation and, compared to alternative cyanide-free technology, with (ii) pressure oxidation followed by halogen leaching. Subsequently, the simulated mass balance was used as life cycle inventory data in order to evaluate the environmental impacts of the predominant cyanidation process and a cyanide-free alternative. Methods The environmental indicators for each scenario are based on the mass balance produced with HSC Sim steady-state simulation. The simulated mass balances were evaluated to identify the challenges in used technologies. The HSC Sim software is compatible with the GaBi LCA software, where LCI data from HSC-Sim is directly exported to. The simulation produces a consistent life cycle inventory (LCI). In GaBi LCA software, the environmental indicators of global warming potential (GWP), acidification potential (AP), terrestrial eutrophication potential (EP), and water depletion (Water) are estimated. Results and discussion The life cycle assessment revealed that the GWP for cyanidation was 10.1 t CO2-e/kg Au, whereas the halogen process indicated a slightly higher GWP of 12.6 t CO2-e/kg Au. The difference is partially explained by the fact that the footprint is calculated against produced units of Au; total recovery by the halogen leaching route for gold was only 87.3%, whereas the cyanidation route could extract as much as 98.5% of gold. The addition of a second gold recovery unit to extract gold also from the washing water in the halogen process increased gold recovery up to 98.5%, decreasing the GWP of the halogen process to 11.5 t CO2-e/kg Au. However, both evaluated halogen processing scenarios indicated a slightly higher global warming potential when compared to the dominating cyanidation technology. Conclusions The estimated environmental impacts predict that the development-stage cyanide-free process still has some challenges compared to cyanidation; as in the investigated scenarios, the environmental impacts were generally higher for halogen leaching. Further process improvements, for example in the form of decreased moisture in the feed for halide leaching, and the adaptation of in situ gold recovery practices in chloride leaching may give the cyanide-free processing options a competitive edge.

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An acidic pressure oxidation pre-treatment of refractory gold concentrates from the KweKwe roasting plant, Zimbabwe

Minerals Engineering ◽

10.1016/s0892-6875(99)00074-6 ◽

1999 ◽

Vol 12 (8) ◽

pp. 863-875 ◽

Cited By ~ 30

Author(s):

F.P. Gudyanga ◽

T. Mahlangu ◽

R.J. Roman ◽

J. Mungoshi ◽

K. Mbeve

Keyword(s):

Pressure Oxidation ◽

Refractory Gold ◽

Pre Treatment

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Induction of chalcone synthase and phenylalanine ammonia-lyase by salicylic acid and Colletotrichum lindemuthianum in common bean

Brazilian Journal of Plant Physiology ◽

10.1590/s1677-04202003000300001 ◽

2003 ◽

Vol 15 (3) ◽

pp. 129-134 ◽

Cited By ~ 33

Author(s):

Ângela Diniz Campos ◽

Alfredo Gui Ferreira ◽

Magdolna Maria Vozári Hampe ◽

Irajá Ferreira Antunes ◽

Nely Brancão ◽

...

Keyword(s):

Enzyme Activity ◽

Salicylic Acid ◽

Common Bean ◽

Phenylalanine Ammonia Lyase ◽

Chalcone Synthase ◽

Colletotrichum Lindemuthianum ◽

Water Control ◽

Leaf Extracts ◽

The Common ◽

Two Stages

The activities of the enzymes chalcone synthase (CHS) and phenylalanine ammonia-lyase (PAL) were measured in leaf extracts obtained from four cultivars of the common bean (AB 136, Rio Tibagi, Carioca and Macanudo). Two stages of plant development were examined: plantlets (V2) and the onset of blooming (R6). Initially, the plants were either treated with salicylic acid or inoculated with the delta race of Colletotrichum lindemuthianum (inductive fungus) and after three days they were evaluated for enzyme activity. Afterwards, all plants were inoculated (challenged) with the virulent pathotype 33/95 of C. lindemuthianum except for the water control. Five days later, the activities of PAL and CHS were evaluated. There were significant changes in the activities of both enzymes three days after treatment with salicylic acid or inductive fungus when compared to the control. Five days after inoculation with with the virulent pathotype 33/95 of C. lindemuthianum CHS activity in the Macanudo was similar to control plants that were not treated with salicylic acid or the inductive fungus but inoculated with 33/95 C. lindemuthianum. The increase in enzyme activity after challenge with 33/95 C. lindemuthianum was greatest for the salicylic acid treatment in the cultivar AB 136, followed by Rio Tibagi and Carioca.

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Common substructures and sequence characteristics of sandwich-like proteins from 42 different folds

10.1101/2020.05.27.108969 ◽

2020 ◽

Author(s):

A.E. Kister

Keyword(s):

Protein Design ◽

Structural Classification ◽

Hydrophobic Residues ◽

Rational Protein Design ◽

The Common ◽

Database Comparison ◽

Two Stages ◽

Sequence Characteristics ◽

Common Sequence

AbstractThis study addresses the following fundamental question: Do sequences of protein domains with sandwich architecture have common sequence characteristics even though they belong to different superfamilies and folds? The analysis was carried out in two stages: determination of substructures in the domains that are common to all sandwich proteins; and detection of common sequence characteristics within the substructures. Analysis of supersecondary structures in domains of proteins revealed two types of four-strand substructures that are common to sandwich proteins. At least one of these common substructures was found in proteins of 42 sandwich-like folds (as per structural classification in the CATH database). Comparison of the sequence fragments corresponding to strands that make up the common substructures revealed specific rules of distribution of hydrophobic residues within these strands. These rules can be conceptualized as grammatical rules of beta protein linguistics. Understanding of the structural and sequence commonalities of sandwich proteins may also be useful for rational protein design.

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Intra-Body Variations of Stable Isotope Ratios (δ13C, δ15N) and Influence of Storage Methods in Aquatic and Post-Aquatic Stages of the Common Toad, Bufo bufo

Water ◽

10.3390/w13182544 ◽

2021 ◽

Vol 13 (18) ◽

pp. 2544

Author(s):

Andrey N. Reshetnikov ◽

Daniil I. Korobushkin

Keyword(s):

Isotope Composition ◽

Bufo Bufo ◽

Common Toad ◽

Δ13c And Δ15n ◽

Isotopic Signatures ◽

The Common ◽

Two Stages ◽

Method Factors ◽

Toad Bufo ◽

Toad Bufo Bufo

Isotopic signatures of carbon and nitrogen are widely used for analysis of the structure of food webs in aquatic ecosystems. The study of animals raises a number of methodological questions, including choice of representative tissues and organs for sampling as well as storage of the studied organisms. Furthermore, the impacts of preservation methods can be tissue-specific, age-specific, and even taxon-specific; thus, studies of these impacts on particular taxa are necessary. We focused on the C and N isotope composition of the common toad (Bufo bufo), one of the most widespread European anuran amphibians. We hypothesized that its different tissues and organs may vary in isotopic composition, and ethanol and freezing may have different effects on isotopic values. Our results showed that both “tissue” and “storage method” factors significantly affected the δ13C values of tadpoles and postmetamorphic juveniles, whereas only the “tissue” factor had a significant effect on the δ15N values. The two stages, tadpoles and postmetamorphs, should be analyzed separately despite the brief postmetamorphic period of the juveniles. The skin, legs, muscles, and tail in tadpoles and legs, muscles and heart in juveniles can be used for δ13C and δ15N analysis regardless of the method of storage. The results will serve for the optimization of future study designs in isotopic ecology.

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