scholarly journals Specific Refractory Gold Flotation and Bio-Oxidation Products: Research Overview

Minerals ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 93
Author(s):  
Richmond K. Asamoah
Keyword(s):  
Oxidation Process ◽  
Chemical Activation ◽  
Systematic Investigation ◽  
Oxidation Products ◽  
Interfacial Chemistry ◽  
Refractory Gold ◽  
Ph Modifier ◽  
Mechanism And Kinetics ◽  
Extraction Performance

This paper presents a research overview, reconciling key and useful case study findings, towards uncovering major causes of gold refractoriness and maximising extraction performance of specific gold flotation and bio-oxidation products. Through systematic investigation of the ore mineralogical and gold deportment properties, leaching mechanisms, and kinetic behaviour and pulp rheology, it was observed that the predominant cause of the poor extraction efficacy of one bio-oxidised product is the presence of recalcitrant sulphate minerals (e.g., jarosite and gypsum) produced during the oxidation process. This was followed by carbonaceous matter and other gangue minerals such as muscovite, quartz, and rutile. The underpining leaching mechanism and kinetics coupled with the pulp rheology were influenced by the feed mineralogy/chemistry, time, agitation/shear rate, interfacial chemistry, pH modifier type, and mechano-chemical activation. For instance, surface exposure of otherwise unavailable gold particles by mechano-chemical activation enhanced the gold leaching rate and yield. This work reflect the remarkable impact of subtle deposit feature changes on extraction performance.

Systematic investigation of non-conformance root cause in prefabrication: a nuclear case study

2021 ◽  
Author(s):  
Steven Chuo ◽  
Qian Chen ◽  
Mohammad Mahdi Sharif ◽  
Carl T. Haas ◽  
Bryan T. Adey
Keyword(s):  
Systematic Investigation ◽  
Root Cause

scholarly journals Thermodynamic simulation of oxidation process of the Moss-Mo3Si hypoeutectic alloy, doped with scandium or neodymium

2019 ◽  
Vol 57 (2) ◽  
pp. 90-100
Author(s):  
Alexey V. Larionov ◽  
◽  
Ludmila Y. Udoeva ◽  
Vladimir M. Chumarev ◽  
◽  
...  
Keyword(s):  
Oxidation Process ◽  
Thermodynamic Simulation ◽  
Oxidation Products ◽  
Hypoeutectic Alloy ◽  
Protective Film ◽  
Chemical Transformations ◽  
Reaction Products ◽  
Moist Air ◽  
Condensed Product ◽  
Hsc Chemistry

In order to study the effect of yttrium additives on the oxidation of molybdenum silicide alloys, thermodynamic modeling of the interaction in Mo-Mo3Si-Sc5Si3 и Mo-Mo3Si-NdSi systems with dry and moist air was performed in the temperature range 25-2000 °C. The calculations were performed using the HSC Chemistry 6.12 software, into the database of which the calculated missing thermochemical characteristics silicates, molybdates of scandium and neodymium were entered. Based on the obtained dependences of the composition of phases on temperature and charge of the oxidant (air or vapor-air mixture), the sequence of phase formation was determined and the compositions of oxidation products were estimated. It is shown that, under equilibrium conditions, the oxidation process with dry and moist air proceeds almost equally, since the interaction of the components of the alloy with oxygen is thermodynamically preferable than with water vapor. According to the obtained thermodynamic models, the oxidation process of the Mo-5Si-3(Sc, Nd) (wt.%) alloys involves a sequence of the following chemical transformations: at the beginning Mo and Sc (Nd) silicides oxidize forming Sc2O3 ( Nd2O3), SiO2 and elemental Mo, then molybdenum is oxidized to MoO2 and Sc2O3 or Nd2O3 interacts with SiO2 with the formation of appropriate silicates Sc2Si2O7 или Nd2Si2O7. As a result of the complete oxidation of the alloy, MoO3 and Sc2(MoO4)3 or Nd2Mo4O15 are added to the condensed product, and molybdenum oxide (MoO3)n vapor appears in the gas phase. In addition, the formation of Nd2Mo2O7 and Nd2 (MoO4)3 is possible. During the oxidation of the Mo-5Si-3Nd alloy at T> 1700 oC, Nd(OH)3 can be formed in the condensed reaction products. According to the results of complete thermodynamic analysis, the formation of silicates and molybdates of scandium and neodymium can promote to the formation of a protective film on the surface of the alloys, which limits the diffusion of oxygen in them, and as a result, the oxidation resistance of alloys should increase.

A systematic investigation of structural transformation in a copper pyrazolato system: a case study

2020 ◽  
Vol 49 (4) ◽  
pp. 1116-1123 ◽  
Author(s):  
Jing-Huo Chen ◽  
Donghui Wei ◽  
Guang Yang ◽  
Jian-Gong Ma ◽  
Peng Cheng
Keyword(s):  
Structural Transformation ◽  
Mixed Valence ◽  
Systematic Investigation ◽  
Structural Conversion ◽  
System A

The mixed-valence CuI3CuII2(OMe)2pz5 has been isolated as a possible key intermediate in the structural conversion from (CuIpz)3/(CuIpz)4 to cyclic hexanuclear CuII species.

Stern Flap for Resistance Reduction of Planing Hull Craft: A Case Study with a Fast Crew Boat Model

2012 ◽  
Author(s):  
Omar Yaakob ◽  
Suhaili Shamsuddin ◽  
Kho King Koh
Keyword(s):  
Reduction Rate ◽  
Cost Effective ◽  
Systematic Investigation ◽  
Percent Reduction ◽  
Geometrical Characteristics ◽  
Resistance Reduction ◽  
Cost Effective Method ◽  
Zero Degree ◽  
Resistance Performance

Kajian terhadap pelbagai cara mengurangkan rintangan bot peronda telah dilakukan oleh ramai penyelidik. Kaedah yang dikaji termasuk penggunaan kepak buritan, baji buritan dan suntikan gelembung mikro. Walau bagaimanapun, disebabkan oleh sifatnya yang mudah dan praktikal, kepak buritan didapati amat berpotensi. Kertas kerja ini membentangkan kajian terhadap kesan kepak buritan terhadap prestasi rintangan bot kelasi berbentuk planing. Ujian model dijalankan bagi membuktikan keberkesanan kepak bagi mengurangkan rintangan. Lima kepak berlainan telah digunakan dalam rangka kajian sistematik bagi menentukan ciri geometrik optimum kepak buritan. Hasil ujian model menunjukkan empat kepak menambah rintangan kapal manakala kepak kelima pada sudut sifar mengurangkan rintangan sehingga 7.2 peratus pada 23 knots dan pengurangan purata sekitar 4.5 peratus. Pada 23 knots, pengurangan 8.2 peratus kuasa berkesan diperolehi. Kata kunci: Reka bentuk bot peronda, ujian model, pesawat laju The study on various methods of reducing the resistance of patrol craft have been carried out by many researchers. These methods included the application of stern flaps, stern wedges, and microbubble injection. However, due to its simplicity and practicality, stern flap is the most promising and cost effective method. The effect of a stern flap on the resistance performance of the planing hull crew boat is presented. Model tests were conducted to prove the effectiveness of the stern flap on reducing planing hull craft resistance. Five different stern flap designs were tested as part of systematic investigation to determine the optimum geometrical characteristics of the stern flap. Results of model resistance experiments showed that four of the flaps tested showed an increase in resistance while the flap at zero degree angle reduced the total resistance by 7.2 percent at 23 knots, and an average reduction rate of 4.5 percent. At 23 knots, an 8.2 percent reduction in effective power was predicted. Key words: Patrol boats design, model testing, fast craft

Mechanism and kinetics of pseudomorphic mineral replacement reactions: A case study of the replacement of pentlandite by violarite

2009 ◽  
Vol 73 (7) ◽  
pp. 1945-1969 ◽  
Author(s):  
Fang Xia ◽  
Joël Brugger ◽  
Guorong Chen ◽  
Yung Ngothai ◽  
Brian O’Neill ◽  
...  
Keyword(s):  
Mechanism And Kinetics ◽  
Mineral Replacement ◽  
Kinetics Of

The refined method of sample preparation and chemical analysis for refractory gold-silver ores: Case study of the Maisk deposit, Primorye

2006 ◽  
Vol 408 (1) ◽  
pp. 547-550 ◽  
Author(s):  
O. V. Loseva ◽  
V. I. Radomskaya ◽  
L. I. Rogulina ◽  
S. M. Radomskii ◽  
V. G. Moiseenko
Keyword(s):  
Chemical Analysis ◽  
Sample Preparation ◽  
Refined Method ◽  
Gold Silver ◽  
Refractory Gold

A photo-oxidation of croconic acid into oxalic acid

1995 ◽  
Vol 73 (8) ◽  
pp. 1298-1304 ◽  
Author(s):  
Paul-Louis Fabre ◽  
Paule Castan ◽  
Diane Deguenon ◽  
Nicole Paillous
Keyword(s):  
Nmr Spectroscopy ◽  
Oxalic Acid ◽  
Electrochemical Oxidation ◽  
Oxidation Process ◽  
Aqueous Media ◽  
Oxidation Products ◽  
Acid Oxidation ◽  
Experimental Conditions ◽  
Photo Oxidation ◽  
C Nmr

Croconic acid, H2C5O5, is readily oxidized. This may be attested by decolorization of the solutions and by observation of oxalic acid complexes. The oxidation products are identified by 13C NMR spectroscopy as oxalic and mesoxalic acids, and experimental conditions are specified. The oxidation process requires dioxygen and photons. In parallel, the electrochemical oxidation of croconic acid is studied in aqueous media and in acetonitrile. A potential–pH diagram is drawn. Keywords: croconic acid, oxalic acid, oxidation, electrochemistry, photochemistry.

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