scholarly journals The Recovery of Cu, Co, Zn, and Mn from a Complex Oxide Ore Using an Enhanced Reduction Leaching

Metals ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. 1636
Author(s):  
Sangyun Seo ◽  
Kyu Sung Han ◽  
Sung Il Lee ◽  
Myong Jun Kim
Keyword(s):  
Sulphuric Acid ◽  
Complex Oxide ◽  
Plant Design ◽  
Two Stage ◽  
Reduction Stage ◽  
Oxidation Reduction ◽  
Mineral Structure ◽  
Current Operation ◽  
Mn Oxides ◽  
Made In

The processing of Cu, Co, and Zn at the Boleo project in Mexico involves two-stage (oxidation–reduction) leaching to extract a total of 85–88% Cu in 4 h. The first stage is an oxidation leaching using sulphuric acid (120 kg/tonne ore) at an Eh of 900 mV for 2 h. Then, the reduction stage takes place in 2 h with SO2 gas sparging for Mn and Co extraction at an Eh of 350–370 mV. The final extraction rates of metal values are 92% of Mn, 80% of Co, and 60% of Co, respectively, after 4 h of leaching at 70 °C. However, the same metal recoveries were obtained within 2 h using an equal amount of sulphuric acid and the addition of 25 kg of SO2 per tonne of ore in a single stage leaching in this research. In this case, the Fe extracted from the ore as Fe2+/Fe3+ is believed to have acted as an electrochemical couple contiguously leaching the Cu sulphide and Mn oxides, which also increased the Cu recovery as the Cu mineralised mostly intergrowths in these mineral structure matrices. A significant improvement was made in which the leaching time was halved to 2 h compared to 4 h in the previous plant design and current operation, involving the two-stage oxidation–reduction leaching.

FURTHER OBSERVATIONS ON THE KOBER COLOUR AND ITTRICH FLUORESCENCE REACTIONS IN THE MEASUREMENT OF OESTRIOL, OESTRONE AND OESTRADIOL

1968 ◽  
Vol 40 (2) ◽  
pp. 175-188 ◽  
Author(s):  
J. B. BROWN ◽  
CAROLINE MACNAUGHTAN ◽  
MARGERY A. SMITH ◽  
BARBARA SMYTH
Keyword(s):  
Sulphuric Acid ◽  
Linear Response ◽  
Two Stage ◽  
Colour Reaction ◽  
One Stage ◽  
Better Than

SUMMARY Higher temperatures allow lower sulphuric acid concentrations and shorter heating times to be used in the Kober colour reaction for oestrogens. A one-stage reaction which is completed in 5 min. at 120° is described for oestrone and oestradiol, and a two-stage reaction which requires two periods of heating for 5 min. at 120° is described for oestriol. The conditions were applied to the Ittrich fluorescence procedure. A spectrophotofluorimetric correction was developed in which fluorescence was measured at wavelengths for excitation and emitted light near the optima for the oestrogens and at another combination at which the oestrogens produced virtually no fluorescence whereas that of impurities was not diminished. Extraction, centrifugation and fluorimetry were performed in specially designed cells. The sensitivity is 0·05–0·1 ng./sample with a linear response up to 300 ng. and a precision better than 4% in the range 1·0–100 ng.

scholarly journals Robust Day-Ahead Dispatch for Integrated Power-Heat-Gas Microgrid considering Wind Power Uncertainty

2020 ◽  
Vol 2020 ◽  
pp. 1-12 ◽  
Author(s):  
Yang Liu ◽  
Yanli Ye ◽  
Xianbang Chen ◽  
Huaqiang Li ◽  
Yuan Huang
Keyword(s):  
Wind Power ◽  
Deterministic Model ◽  
Economic Dispatch ◽  
Two Stage ◽  
Worst Case ◽  
Constraint Generation ◽  
Second Stage ◽  
Robust Model ◽  
Operation Cost ◽  
Made In

Wind power generation has been widely deployed in the modern power system due to the issues of energy crisis and environment pollution. Meanwhile, the microgrid is gradually regarded as a feasible way to connect and accommodate the distributed wind power generations. Recently, more research studies also focus on incorporating various energy systems, for example, heat and gas into the microgrid in terms of satisfying different types of load demands. However, the uncertainty of wind power significantly impacts the economy of the integrated power-heat-gas microgrid. To deal with this issue, this paper presents a two-stage robust model to achieve the optimal day-ahead economic dispatch strategy considering the worst-case wind power scenarios. The first stage makes the initial day-ahead dispatch decision before the observation of uncertain wind power. The additional adjustment action is made in the second stage once the wind power uncertainty is observed. Based on the duality theory and Big-M approach, the original second-stage problem can be dualized and linearized. Therefore, the column-and-constraint generation algorithm can be further implemented to achieve the optimal day-ahead economic dispatch strategy for the integrated power-heat-gas microgrid. The experimental results indicate the effectiveness of the presented approach for achieving operation cost reduction and promoting wind power utilization. The robustness and the economy of the two-stage robust model can be balanced, of which the performances significantly outperform those of the single-stage robust model and the deterministic model.

scholarly journals Dynamic variation of supernatant quality in a dairy shed waste stabilisation pond system

2007 ◽  
Vol 55 (11) ◽  
pp. 245-255 ◽  
Author(s):  
J. Fyfe ◽  
M. Sivakumar ◽  
D. Hagare ◽  
A. Jenkins
Keyword(s):  
Dissolved Oxygen ◽  
Vertical Mixing ◽  
Monitoring Program ◽  
Spatial And Temporal Variation ◽  
Chemical Parameters ◽  
Two Stage ◽  
Spatial Homogeneity ◽  
Pond System ◽  
Oxidation Reduction ◽  
External Stimuli

An intensive monitoring program of a standard two-stage dairy shed waste stabilisation pond system was undertaken to determine the incidence and extent of spatial and temporal variation of basic physio-chemical parameters, and to shed light on the longer term dynamic nature of in-pond conditions. The anaerobic–facultative pond system, located in a remote rural area, treats wastewater from the hosing down and hydraulic flushing of the milking parlour and holding yard at the farm dairy shed. A number of multi-parameter water quality field monitoring probes were permanently deployed at various locations within the two ponds to enable continuous measurement of temperature, pH, conductivity and dissolved oxygen. In addition, profiling of the supernatant of both ponds was undertaken at different times of the year to examine vertical variation of the same parameters. Continuous monitoring revealed spatial homogeneity in EC and pH levels in the upper metre of both ponds. Physio-chemical parameters also appear to change uniformly across the ponds in response to external stimuli such as rainfall. Neither pond, however, exhibits homogeneity down the profile of the supernatant. Seasonal stratification is prevalent in the facultative pond suggesting poor vertical mixing, while the anaerobic pond is notably affected by sludge accumulation. A long-term pattern of rising conductivity in both ponds indicated accumulation of dissolved salt species in the system due to recirculation of reclaimed effluent for hydraulic flushing of the dairy shed. In the facultative pond, diurnal fluctuations in dissolved oxygen, oxidation-reduction potential and turbidity during warmer months of the year closely followed temperature swings. The extensive data collected in this study provides a detailed picture of the physio-chemical dynamics of two-stage stabilisation pond systems treating dairy shed wastewater.

Typical Metrology of Micro-Hole Arrays Made in Stainless Steel Foils by Two-Stage Micro-EDM

CIRP Annals ◽  
1999 ◽  
Vol 48 (1) ◽  
pp. 127-130 ◽  
Author(s):  
D.M. Allen ◽  
H.J.A. Almond ◽  
J.S. Bhogal ◽  
A.E. Green ◽  
P.M. Logan ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Micro Edm ◽  
Two Stage ◽  
Micro Hole ◽  
Hole Arrays ◽  
Stainless Steel Foils ◽  
Steel Foils ◽  
Made In

Kinetic studies of two-stage sulphuric acid hydrolysis of sugarcane bagasse

2015 ◽  
Vol 83 ◽  
pp. 850-858 ◽  
Author(s):  
Sachin Kumar ◽  
Pratibha Dheeran ◽  
Surendra P. Singh ◽  
Indra M. Mishra ◽  
Dilip K. Adhikari
Keyword(s):  
Acid Hydrolysis ◽  
Sulphuric Acid ◽  
Sugarcane Bagasse ◽  
Kinetic Studies ◽  
Two Stage ◽  
Hydrolysis Of

Iron(III) complexes of DL-methionine

1972 ◽  
Vol 25 (2) ◽  
pp. 421 ◽  
Author(s):  
EJ Halbert ◽  
MJ Rogerson
Keyword(s):  
Aqueous Solution ◽  
Amino Acids ◽  
Large Excess ◽  
Ph Titration ◽  
Oxidation Reduction ◽  
Infrared Studies ◽  
Rapid Hydrolysis ◽  
Iron Analysis ◽  
Hydrolysis Of ◽  
Made In

Few iron(111) complexes of amino acids have been isolated although attempts have been made to measure their stabilities in solution. Iron(111) in the presence of various amino acids showed no complex formation during pH titration in aqueous solution. Using oxidation-reduction and spectrophotometric techniques Perrin measured the stabilities of 1 : 1 complexes of iron(111) with different amino acids in solutions of low pH. Rapid hydrolysis of iron(111) occurred when the pH was increased even in the presence of a large excess of amino acids. Bielig and Bayer reported the isolation of a bis-complex of iron(111) and methionine prepared in aqueous solution. McAuliffe, Quagliano, and Vallarinoe reported a tris-complex made in ethanol, though their iron analysis was not consistent with the required structure. In both cases magnetic and infrared studies were used to characterize the products. Our attempts to repeat these preparations were unsuccessful. This paper describes the preparation of two 1 : 1 complexes of methionine and iron(111) and an investigation of their properties by analysis of infrared, magnetic, and N.M.R. measurements.

scholarly journals VOC measurements within a boreal forest during spring 2005: the role of monoterpenes and sulphuric acid in selected intense nucleation events

2009 ◽  
Vol 9 (3) ◽  
pp. 12781-12827 ◽  
Author(s):  
G. Eerdekens ◽  
N. Yassaa ◽  
V. Sinha ◽  
P. P. Aalto ◽  
V. Fiedler ◽  
...  
Keyword(s):  
Boreal Forest ◽  
Sulphuric Acid ◽  
Trace Gases ◽  
Measurement Data ◽  
Event Type ◽  
Field Campaign ◽  
Back Trajectories ◽  
Made In

Abstract. In this study we present measurements of selected trace gases and aerosol made in a boreal forest during the BACCI-QUEST IV intensive field campaign in Hyytiälä, Finland in April 2005. Several clear aerosol "nucleation events" were observed and characterized. One type of "event" occurred synchronously with huge increases in monoterpenes, while a second event type correlated instead with sulphuric acid. Here we elucidate the origin of these two distinct forms of aerosol production at the Hyytiälä site using the measurement data, airmass back trajectories and the optical stereoisomery of monoterpenes.

Biological Treatment for Low-Activity Nuclear Wastewaters

1987 ◽  
Vol 19 (3-4) ◽  
pp. 345-353
Author(s):  
R. Ramadori ◽  
F. Fenoglio ◽  
L. Pozzi
Keyword(s):  
Wastewater Treatment ◽  
Organic Compound ◽  
Biological Treatment ◽  
Chemical Precipitation ◽  
Nuclear Industry ◽  
Plant Design ◽  
Liquid Wastes ◽  
Low Activity ◽  
Denitrification Process ◽  
Made In

Safety problems loom so large for the nuclear industry that provision must always be made in treatment of liquid wastes for their recycling to the production process. In this regard, a wastewater treatment consisting mainly of ammonia stripping, biological denitrification and chemical precipitation, looks very promising. With reference to the biological stage, this paper sets out the results of bench-scale tests performed to evaluate dimensioning parameters for the denitrification process. The tetrahydrofurfury1 alcohol, the major organic compound in the wastewater, was used as electron-donor substance. The procedure adopted for full-scale plant design and the preliminary results obtained using it, are also presented.

Oxidoreductases: Significance for Humans and Microorganism

2020 ◽  
Author(s):  
Hussein Mahdi Kareem
Keyword(s):  
Large Class ◽  
Electron Donor ◽  
Electron Acceptor ◽  
Diagnostic Tests ◽  
Organic Substrates ◽  
Biochemical Reactions ◽  
Biomass Processing ◽  
Oxidation Reduction ◽  
Special Case ◽  
Made In

Oxidoreductases consist of a large class of enzymes catalyzing the transfer of electrons from an electron donor (reductant) to an electron acceptor (oxidant) molecule. Since so many chemical and biochemical transformations comprise oxidation/reduction processes, it has long been an important goal in biotechnology to develop practical biocatalytic applications of oxidoreductases. During the past few years, significant breakthrough has been made in the development of oxidoreductase-based diagnostic tests and improved biosensors, and the design of innovative systems for the regeneration of essential coenzymes. Research on the construction of bioreactors for pollutants biodegradation and biomass processing, and the development of oxidoreductase-based approaches for synthesis of polymers and functionalized organic substrates have made great progress. Proper names of oxidoreductases are in a form of “donor:acceptor oxidoreductase”; while in most cases “donor dehydrogenase” is much more common. Common names also sometimes appeared as “acceptor reductase”, such as NAD+ reductase. “Donor oxidase” is a special case when O2 serves as the acceptor. In biochemical reactions, the redox reactions are sometimes more difficult to observe, such as this reaction from glycolysis: Pi + glyceraldehyde-3-phosphate + NAD+ → NADH + H+ + 1,3-bisphosphoglycerate, where NAD+ is the oxidant (electron acceptor), and glyceraldehyde-3-phosphate functions as reductant (electron donor).

Influence of Oxidation-Reduction Potential on Bio-Oxidation of Olimpiada Flotation Concentrate with High Content of Pyrrhotite

2015 ◽  
Vol 1130 ◽  
pp. 161-164
Author(s):  
Aleksandr Belyi ◽  
Sergei Drozdov ◽  
Anatoliy Teleutov ◽  
Natalia Solopova
Keyword(s):  
Sulphuric Acid ◽  
Oxidation Rate ◽  
Reduction Potential ◽  
Pyrite Oxidation ◽  
Research Work ◽  
Stable Process ◽  
Flotation Concentrate ◽  
Oxidation Reduction ◽  
Oxidation Reduction Potential ◽  
Acid Consumption

The main sulphidic minerals, contained in the Olimpiada flotation concentrate, are pyrrhotite, arsenopyrite, pyrite and antimonite. Biooxidation of these minerals occurs in the following sequence: Pyrrhotite → Arsenopyrite → Pyrite → Antimonite. Oxidation of pyrrhotite requires acid consumption, oxidation of pyrite is followed by formation of sulphuric acid. The oxidation rate of pyrrhotite is higher and due to this, acid balance of the whole biooxidation process is shifted to the consuming side, and it is required to add acid to the process. The research work has demonstrated, that by regulating oxidation-reduction potential it is possible to reduce pyrrhotite oxidation rate and intensify pyrite oxidation rate; this allows to reduce consumption of sulphuric acid, reduce heating of the slurry inside the reactors and as a result maintain the stable process.

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