Study of selective reduction in lateritic nickel ore: Saprolite versus limonite

2021 ◽  
Author(s):  
Fajar Nurjaman ◽  
Widi Astuti ◽  
Fathan Bahfie ◽  
Bambang Suharno
Keyword(s):  
Selective Reduction ◽  
Lateritic Nickel

Research on Selective Reduction of Laterite Nickel Ore by CO2/H2 Mixed Gas

2014 ◽  
Vol 1025-1026 ◽  
pp. 814-819
Author(s):  
Song Chen ◽  
Shu Qiang Guo ◽  
Yu Ling Xu ◽  
Lan Jiang ◽  
Wei Zhong Ding
Keyword(s):  
Activity Theory ◽  
Thermodynamic Analysis ◽  
Calculation Result ◽  
Gas Flow ◽  
Selective Reduction ◽  
Mixed Gas ◽  
Metallization Rate ◽  
Lateritic Nickel ◽  
Laterite Ore

In this paper, thermodynamic analysis on reduction of lateritic nickel ore by CO2/H2 mixed gas was performed based on activity theory. Effects of CO2/H2 ratio and temperature on selective reduction of laterite ore were investigated. The calculation result shows that the metallization of Fe and Ni could be promoted by each other because of the variation of the Fe and Ni activity, which accounts for the inescapability of Fe metallization. When laterite nickel ore was reduced by mixed gas with a CO2/H2 ratio of 9/1 and a gas flow of 100mL/min at 800°C for 1h, a product with a Ni metallization rate over 95% and a Ni/Fe ratio as much as 2.6 was prepared.

scholarly journals Selective Reduction of High Alumina-Lateritic Nickel Ore (0.5 Ni-44Fe-16Al2O3)

2019 ◽  
Vol 14 (2) ◽  
pp. 130-138
Author(s):  
Fajar Nurjaman ◽  
Wahyuningsih Wahyuningsih ◽  
Pulung Karo Karo ◽  
Ediman Ginting ◽  
Achmad Shofi ◽  
...  
Keyword(s):  
Selective Reduction ◽  
Reduction Process ◽  
Holding Time ◽  
High Alumina ◽  
Reduction Temperature ◽  
X Ray Diffraction ◽  
Optimal Process ◽  
X Ray ◽  
Lateritic Nickel ◽  
Iron Grade

In this present study, the effect of reductant dosage, temperature and holding time on selective reduction process of high alumina-lateritic nickel ore have been investigated clearly. The lateritic nickel ore was reduced with 5 until 15 wt. % anthracite and 10 wt. % sodium sulfate at reduction temperature of 950ºC, 1050ºC and 1150°C for 60, 90, and 120 minutes. Magnetic separation process was then conducted to separate the concentrate and tailing. The analysis of reduced nickel ore is performed by the Atomic Absorption Spectroscopy, X-Ray Diffraction, and Secondary Electron Microscopy. The optimal process resulted from the reduction of nickel ore with 10 wt. % anthracite at the temperature of 1050°C for 120 minutes which resulted in 0.84% nickel in concentrate. The troilite was not found in reduced ore. The iron grade increased along the increased of reduction temperature. The longer of holding time in selective reduction process increased the nickel grade but it decreased the iron grade.

Metal-Free Photoredox-Catalyzed C–H/C–H Coupling of Arenes Enabled by Interrupted Pummerer Activation

2019 ◽  
Author(s):  
Miles Aukland ◽  
Mindaugas Šiaučiulis ◽  
Adam West ◽  
Gregory Perry ◽  
David Procter
Keyword(s):  
Natural Product ◽  
Selective Reduction ◽  
Cross Coupling ◽  
One Pot ◽  
Complex Molecules ◽  
Pummerer Reaction ◽  
Metal Free ◽  
Bond Forming ◽  
Coupling Partner ◽  
Bioactive Natural Product

<p>Aryl–aryl cross-coupling constitutes one of the most widely used procedures for the synthesis of high-value materials, ranging from pharmaceuticals to organic electronics and conducting polymers. The assembly of (hetero)biaryl scaffolds generally requires multiple steps; coupling partners must be functionalized before the key bond-forming event is considered. Thus, the development of selective C–H arylation processes in arenes, that side-step the need for prefunctionalized partners, is crucial for streamlining the construction of these key architectures. Here we report an expedient, one-pot assembly of (hetero)biaryl motifs using photocatalysis and two non-prefunctionalized arene partners. The approach is underpinned by the activation of a C–H bond in an arene coupling partner using the interrupted Pummerer reaction. A unique pairing of the organic photoredox catalyst and the intermediate dibenzothiophenium salts enables highly selective reduction in the presence of sensitive functionalities. The utility of the metal-free, one-pot strategy is exemplified by the synthesis of a bioactive natural product and the modification of complex molecules of societal importance.</p>

Diastereoselective Reduction of Selected α-substituted β-keto Esters and the Assignment of the Relative Configuration by 1H-NMR Spectroscopy

2020 ◽  
Vol 07 ◽  
Author(s):  
Christian Trapp ◽  
Corinna Schuster ◽  
Chris Drewniok ◽  
Dieter Greif ◽  
Martin Hofrichter
Keyword(s):  
Nmr Spectroscopy ◽  
1H Nmr ◽  
1H Nmr Spectroscopy ◽  
Selective Reduction ◽  
Reducing Agents ◽  
Relative Configuration ◽  
Curtius Rearrangement ◽  
Keto Esters ◽  
Hydroxy Esters ◽  
Diastereoselective Reduction

Background:: Chiral β-hydroxy esters and α-substituted β-hydroxy esters represent versatile building blocks for pheromones, β-lactam antibiotics and 1,2- or 1,3-aminoalcohols. Objective:: Synthesis of versatile α-substituted β-keto esters and their diastereoselective reduction to the corresponding syn- or anti-α-substituted β-hydroxy esters. Assignment of the relative configuration by NMR-spectroscopy after a CURTIUS rearrangement of α-substituted β-keto esters to 4-substituted 5-methyloxazolidin-2-ones. Method:: Diastereoselective reduction was achieved by using different LEWIS acids (zinc, titanium and cerium) in combination with complex borohydrides as reducing agents. Assignment of the relative configuration was verified by 1H-NMR spectroscopy after CURTIUS-rearrangement of α-substituted β-hydroxy esters to 4-substituted 5-methyloxazolidin-2-ones. Results:: For the syn-selective reduction, titanium tetrachloride (TiCl4) in combination with a pyridine-borane complex (py BH3) led to diastereoselectivities up to 99% dr. High anti-selective reduction was achieved by using cerium trichloride (CeCl3) and steric hindered reducing agents such as lithium triethylborohydride (LiEt3BH). After CURTIUS-rearrangement of each α-substituted β-hydroxy ester to the corresponding 4-substituted 5-methyloxazolidin-2-one, the relative configuration was confirmed by 1H NMR-spectroscopy. Conclusion:: We have expanded the procedure of LEWIS acid-mediated diastereoselective reduction to bulky α-substituents such as the isopropyl group and the electron withdrawing phenyl ring.

Synthesis of 11-hydroxylated androstane derivatives

1980 ◽  
Vol 45 (6) ◽  
pp. 1845-1849 ◽  
Author(s):  
Jan Fajkoš ◽  
Jiří Joska
Keyword(s):  
Selective Reduction ◽  
Reaction Conditions ◽  
Androstane Derivatives

Reaction conditions for selective reduction of 3- and 17-oxo groups are described and applied to syntheses of 11-hydroxylated derivatives.

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