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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

2022

T. 38, z. 1

123--136

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.

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.

Effect of fluidized magnetizing roasting on iron recovery and transformation of weakly magnetic iron mineral phasein iron tailings

Li Wenbo, Han Yuexin, Liu Xiao, Shan Yan, Li Yanjun

Physicochemical Problems of Mineral Processing

2019

Vol. 55, iss. 4

906--916

The eastern tailings of the Anshan mining area are generally categorized as high silicon-bearing iron tailings, and the iron mainly exists in the form of hematite–limonite with an iron grade of 10.60%. In order to recover iron minerals and reduce the influence of the tailings on the environment, a method for pre-enrichment through the combination of low intensity magnetic separation and high intensity magnetic separation with fluidized magnetizing roasting and subsequent low intensity magnetic separation was developed to treat the eastern tailings of the Anshan mining area. The effects of gas-flow rate, H2 concentration, roasting temperature, and roasting time on the quality of the final iron concentrate were discussed. Moreover, the iron phase transformation and change in magnetism of the sample were studied. The results indicated that an iron concentrate with an iron grade of 65.30% and a recovery of 85.85% could be obtained under the conditions of gas-flow rate of 8 m3/h, H2 concentration of 50%, and fluidized magnetizing roasting at 600 ℃ for 20 s. X-ray diffraction analysis, phase analysis, and magnetism analysis on the roasted materials indicated that the hematite–limonite could be transformed into magnetite during the fluidized magnetizing roasting process, and effective separation of iron and gangues could be easily achieved by the weak magnetic separation.

Photon attenuation properties of concretes containing magnetite and limonite ores

Gur A., Artig B., Cakir T.

Physicochemical Problems of Mineral Processing

2017

Vol. 53, iss. 1

184--191

In this study, gamma shielding properties of concretes containing magnetite and limonite ores at different ratios (5%, 10%, 15%, 20%, and 30%) were investigated by using a 60Co (1.25 MeV) radioactive source which was built in Thratron 1000E™ device used for radiotherapy purposes. Then, the photon transmission values (I/I0) were measured by 0.6 cm3, farmer type, PTW™ ion chamber. The dose readings (I0 and I), made by PTW™ Unidose Electrometer, were used to calculate the linear attenuation coefficient (, cm-1), the mean free path (, cm), and the mass attenuation coefficient (, cm2/g) by the Lambert equations, and the results were compared with the calculations obtained using the WinXCom computer program. The findings from this study revealed that the concretes containing magnetite and limonite ores were more effective than the ordinary concrete in the attenuation of gamma rays. It was determined that the values of the mean free path decreased with the increasing concentrations of magnetite and limonite ores while the linear attenuation coefficients for 10 concrete blocks increased with the increasing magnetite and limonite ore concentrations. A comparison of the theoretical values obtained from the WinXCom computer program and the experimental results revealed a good level of conformity.