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1

Recovery of Fe and V via selective reduction–magnetic separation of vanadium-titanium magnetite concentrate

Liu Liwei, Li Guofeng, Zhao Libing, Li Jinpeng, Li Yanfeng

Physicochemical Problems of Mineral Processing

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2022

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Vol. 58, iss. 1

50--62

EN

With the aim of separating Fe and V, a vanadium-titanium magnetite concentrate was selectively reduced, followed by magnetic separation. The processes accompanying reduction of the vanadium-titanium magnetite concentrate were investigated using thermodynamic simulation, experiments, scanning electron microscopy, and electron probe microanalysis. Appropriate reduction conditions and controlling the amount of CaCO3 promoted the reduction of Fe-containing minerals to metallic Fe. V was released from magnetite, ilmenite, and titanomagnetite, and was inhibited to reduce to metallic V, leading to V enrichment in the non-magnetic products in the form of oxides. Moreover, the Fe particles wrapped the slag phase when the amount of CaCO3 exceeded 8%, which is unfavourable for the magnetic separation of Fe and V. Magnetic products with an Fe content of 87.19%, Fe recovery of 82.62%, V content of 0.09% and non-magnetic products with a V content of 1.00% and a V recovery of 85.49% were obtained when the vanadium-titanium magnetite concentrate was reduced for 100 min at 1623 K with a C/O molar ratio of 2.5 and 8% CaCO3, followed by separating at a magnetic field strength of 85 mT.

2

The effect of sulfur, temperature, the duration of the process and reductant on the selective reduction of limonite ore

Bahfie Fathan, Shofi Achmad, Herlina Ulin, Handoko Anton S., Septiana Nanda A., Syafriadi Syafriadi, Suharto Suharto, Sudibyo Sudibyo, Suhartono Suhartono, Nurjaman Fajar

Gospodarka Surowcami Mineralnymi

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2022

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T. 38, z. 1

123--136

EN

Lateritic nickel ore is used for producing of ferronickel. Nickel grade in ferronickel ranged from 20–40%. Ferronickel is commonly used to manufacture stainless steel. A new method that can increase the levels of nickel grade is selective reduction, which is a process to reduce the metal oxide to the metallic phase with the addition of additives. In this work, the selective reduction of limonitic nickel ore was carried out by add the 5 wt%, 10 wt%, and 15 wt% of reductant and the 10 wt% of sulfur as additive. The process of selective reduction is performed at temperatures of 950, 1050, and 1150°C with the duration of processs of 60, 90, and 120 minutes, followed by magnetic separation to separate between the concentrate and tailings. The characterization used AAS, XRD, and SEM-EDS for grade and recovery; phases transformation; and the microstructure analysis. The optimum of the grade and recovery of nickel was obtained at a temperature of 1050°C with the duration of process of 60 minutes and 5 wt% of reductant and 10 wt% of additive, which obtain 3.72 wt% and 95.67%. The metal grade and recovery was increase with the increasing of temperature reduction. Nevertheless, too long of the duration of process and too many reductant addition resulted in negative effect on selective reduction of lateritic nickel ore. Highest recovery could get more nickel in the process. And sulfur has the important rules when the selective reduction has been done on the increasing nickel content, the forming of FeS, and decreasing the grain size of ferronickel according to the microstructure in the SEM images around ~30 µm.

PL

Ruda laterytowa niklu jest wykorzystywana do produkcji żelazoniklu. Zawartość niklu w żelazoniklu wahała się w przedziale 20–40%. Żelazonikiel jest powszechnie stosowany do produkcji stali nierdzewnej. Nową metodą, która może zwiększyć poziom niklu, jest redukcja selektywna, czyli proces redukcji tlenku metalu do fazy metalicznej z dodatkami. W niniejszej pracy prowadzono selektywną redukcję rudy limonitowej niklu przez dodanie 5, 10 i 15% wag. reduktora oraz 10% wag. siarki jako dodatku. Proces selektywnej redukcji odbywa się w temperaturach 950, 1050 i 1150°C z czasem trwania 60, 90 i 120 minut, po czym następuje separacja magnetyczna w celu oddzielenia koncentratu od odpadów. Zastosowano: AAS, XRD i SEM-EDS do oceny procesu, transformację faz oraz analizę mikrostruktury. Optimum stopnia odzysku niklu uzyskano w temperaturze 1050°C przy czasie trwania procesu 60 minut i 5% mas. reduktora i 10% mas. dodatku, co daje 3,72% mas. i 95,67%. Gatunek i odzysk metalu wzrastały wraz z obniżeniem temperatury. Niemniej jednak zbyt długi czas trwania procesu i zbyt częste dodawanie reduktora skutkowało negatywnym wpływem na selektywną redukcję laterytowej rudy niklu. Przy najwyższym odzysku można w tym procesie uzyskać więcej niklu. A siarka spełnia ważną rolę, gdy selektywna redukcja została przeprowadzona w celu zwiększenia zawartości niklu, tworzenia FeS i zmniejszenia wielkości ziarn żelazoniklu, zgodnie z mikrostrukturą na obrazach SEM około ~30 µm.

3

Ocena wpływu dawki amoniaku na poziom konwersji NOx w platynowym reaktorze SCR

Kamela W., Kruczyński S.

Logistyka

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2012

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nr 3

PL

W pracy przedstawiono porównanie wyników badań platynowego reaktora redukującego systemu NH3-SCR przy różnym dawkowaniu amoniaku do układu wydechowego silnika o zapłonie samoczynnym. Porównania dokonano w aspekcie oceny zdolności reaktora do konwersji tlenków azotu za pośrednictwem amoniaku. W pracy zamieszczono wyniki badań fizyko-chemicznych struktury powierzchni aktywnej reaktora wykonanych przy pomocy mikroskopu SEM. Przedstawiono obrazy topografii powierzchni aktywnej oraz punktową analizę jej składu chemicznego. Opracowanie zawiera wyniki obliczeń konwersji NOX i NO oraz udziału NO2 w NOX, w funkcji temperatury pracy reaktora wraz z wyznaczonymi dla niego charakterystycznymi parametrami pracy. W artykule zamieszczono wyniki pomiarów ucieczki amoniaku mierzonej za reaktorem. Uzyskane wyniki badań wykazały możliwość zastosowania reaktora platynowego do redukcji tlenków azotu amoniakiem jedynie w wąskim zakresie temperatury. Wykazano wpływ wzrostu stężenia amoniaku przed reaktorem na wzrost uzyskiwanych poziomów konwersji NOX oraz zwiększenie ucieczki NH3.

EN

This paper contains results comparison of platinum catalytic reactor working as a reduction reactor for NH3-SCR system with different ammonia doses in Diesel engine exhaust gases. Results comparison was made in aspect of reactor ability estimation in nitric oxides conversion by use of ammonia. In this study results of physical-chemical investigations under reactor active surface are presented. Investigations were made by use of SEM microscope and they contains reactor surface topography views and chemical composition analysis. Article contains calculation results of NOX and NO conversion and NO2 contribution in NOX in function of reactor temperature. Characteristic reactor work parameters were also determinate in this paper. Results of ammonia slip measurements after reactor are included. Obtained results have shown that platinum reactor can be used for nitric oxides reduction by use of ammonia only in narrow temperature range. Influence of ammonia concentration increase before reactor on NOX conversion levels increase and ammonia slip increase was reported.

4

Examination of the ammonia dose influence on nitric oxides transformations into combined oxide - platinum SCR catalyst

Kamela W., Kruczyński S.

Journal of KONES

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2012

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Vol. 19, No. 4

253-258

EN

This paper presents the test results obtained from the combined oxide-platinum catalytic reactor used in the NH3-SCR system. The first reactor block was extracted from the oxide catalyst used in trucks. As the second module of the reactor a block with platinum acting as a catalyst was used with 2.5g/dm3 platinum load. During the tests the ammonia concentrations in the engine exhaust gases at the inlet of the reactor system were set to 240, 320 and 400 ppm. The article contains the results of the physical and chemical active surface structure tests of both reactor blocks with their active surface chemical microanalysis and its topographic pictures performed and taken with the Scanning Electron Microscope. The results of the NOX and NO conversion and the content of NO2 in NOX are presented in this paper as the function of combined reactors system operating temperature with three different ammonia concentrations in the exhaust gases. Additionally, the results of the measured ammonia slip at the outlet of the combined reactor were presented. The obtained results have shown that the increase in ammonia dose at the inlet of the system increases the nitric oxides conversion with the minimum influence on the ammonia slip. By using the platinum based catalyst block it was possible to widen the whole reactor system effective operating temperature due to the high nitric oxides conversion efficiency of the platinum block achieved at low operating temperatures. A low ammonia slip at the outlet of the combined catalytic reactor was obtained by use of the platinum reactor block whose properties allow for the high ammonia conversion.

5

Estimation of nox conversion into oxide, platinum and combined oxide - platinum SCR catalyst

Kamela W., Kruczyński S.

Journal of KONES

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2012

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Vol. 19, No. 3

195-202

EN

The paper contains the results of the tests of the oxide, platinum and combined oxide-platinum catalytic reactor model used in the NH3-SCR system. As regards the combined oxide-platinum catalyst the first reactor block was extracted from the oxide catalyst used in trucks. As the second module of the reactor a block with platinum acting as a catalyst was used with 2.5g/dm3 platinum load. The only differences between the combined reactor system and the single platinum and oxide catalysts were connected with the reactors volume which in the case of the single reactors was two times higher than the volume of the corresponding blocks of the combined system. During the tests the ammonia concentration in the engine exhaust gases at the inlet of the reactors was set to 400 ppm. The article contains the results of the physical and chemical active surface structure tests of the reactors with their active surface chemical microanalysis and its topographic pictures performed and taken with the Scanning Electron Microscope. The results obtained from the tests of the influence of the reactor type on the NOX and NO conversion and the content of NO2 in NOX are presented in this article in the form of the function of their operating temperature. Additionally, the results of measured ammonia slip at the outlet of the reactors are presented. The obtained results have shown that the usage of the combined oxide-platinum reactor allows for widening the SCR system effective operating temperature range with a low ammonia slip at its outlet. This was achieved by use of the platinum reactor block which features a high nitric oxides conversion efficiency at the operating temperatures which are lower than those of the oxide catalyst and which can also provide the high ammonia spices conversion rangeto lower the ammonia slip at system outlet.

6

Katalityczne ograniczanie emisji tlenków azotu w silnikach spalinowych

Kruczyński S. W.

Transport Samochodowy

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2003

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z. 1

113--125

PL

W pracy dokonano klasyfikacji katalitycznych metod usuwania tlenków azotu ze spalin silników tłokowych. Omówiono zagadnienia rozkładu NOx i redukcji NOx metodami NH3-SCR i HC-SCR w spalinach zawierających duże ilości tlenu. Opisano również metody wspomagające procesy katalityczne takie jak elektrokataliza i zimna plazma.

EN

The present paper gives an general classification of catalytic methods of NOx elimination from exhaust gas of piston engines. Problems connected with NOx decomposition and reduction are discussed, as well as research problems appearing at realization of these processes using NH3-SCR and HC-SCR methods, in exhaust gas with high oxygen contents. Methods supporting and enhancing catalytic processes, such as electro-catalysis and cold plasma.

7

The Efficient Synthesis of Azaamino Acids

Wieczerzak E., Kozlowska J., Łankiewicz L., Grzonka Z.

Polish Journal of Chemistry

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2002

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Vol. 76 / nr 12

1693-1697

EN

An efficient method of synthesis of N-t-butoxycarbonyl-azaamino acid ethyl esters has been described. This method consisted of three stages including: hydrazone formation, its reduction and acylation with ethyl chloroformate. The second step - reduction of the hydrazones to the appropriate hydrazides - was the most challenging. Some reducing agents have been tested, though NaBH3CN was found to lead to the final products with the highest yields in relatively short time and even to allow the selective reduction of C-N bond in the presence of nitro group.