Gördes Lateritinin CO Atmosferinde İzotermal Olmayan İndirgenme Kinetiği

Öz

Nikel metaline yönelik her geçen gün artan talebe rağmen sülfit yataklarının tükeniyor oluşu sektörün yönünü düşük Ni içeriği ve yüksek enerji gerektirmesi dolayısıyla birincil kaynak olarak pek tercih edilmeyen laterit yataklarına çevirmiştir. Dolayısıyla hem maliyetleri hem de sera gazı emisyonları düşürerek bu cevherleri etkin şekilde işleyebilmek için alternatif yolların bulunması elzemdir. Lateritlerdeki nikelin kazanılması için katı faz indirgenmesi ve akabinde magnetik yolla ayırma cazip bir seçenektir. Bu nedenle bu çalışma Gördes lateritinin (Manisa, Türkiye) farklı ısıtma hızlarında (20, 25, 30, 35, ve 45 ºC/dak.) izotermal olmayan indirgenme kinetiğini konu almıştır. Aktivasyon enerjileri Friedman (FR), Kissinger-Akahira-Sunose (KAS), ve Flynn-Wall-Ozawa (FWO) yöntemleriyle, hızı kontrol eden mekanizmalar ise Sestak-Berggren Eşitliğinin Malek yorumu ile belirlenmiştir. İndirgenme prosesi, kinetik analiz sonuçlarına dayanılarak sırasıyla "0 ile 0,16", "0,16 ile 0,45", and "0,45 ile 0,7" indirgenme dereceleri arasında yer alan üç bölgeye ayrılmıştır. İlk bölgenin 53 kJ/mol’ lük bir aktivasyon enerjisiyle, arayüz reaksiyon kontrolü altında gerçekleştiği, ikinci ve üçüncü bölgelerin ise sırasıyla 126 kJ/mol ve 379 kJ/mol’ lik aktivasyon enerjisiyle, karışık kontrollü olarak gerçekleştiği belirlenmiştir.

Anahtar Kelimeler

• Nikel
• laterit
• izotermal olmayan TGA
• kinetik modelleme
• Sestak-Berggren eşitliği

Non-isothermal Reduction Kinetics of Gördes Laterite in CO Atmosphere

Öz

The growing demand for nickel metal and the depletion of high-grade sulfide ore reserves have turned the direction of industry towards laterites which are not desirable as the primary source due to their low Ni content and more energy-intensive processing. Thus, alternative routes are essential for effectively processing these ores while reducing the costs and greenhouse gas emissions. Solid-state reduction followed by magnetic separation is an attractive option for recovering the nickel in laterites. Hereby, this study analyzed the non-isothermal reduction kinetics of nickel laterite from Gördes (Manisa, Turkey) by CO at different heating rates of 20, 25, 30, 35, and 45 ºC/min. The activation energies were determined by Friedman (FR), Kissinger-Akahira-Sunose (KAS), and Flynn-Wall-Ozawa (FWO) methods, and the controlling mechanisms were determined by the Malek interpretation of the Sestak-Berggren Equation. The reduction process was divided into three stages which take place between "0 to 0.16", "0.16 to 0.45", and "0.45 to 0.7" reduction degrees respectively according to the kinetic analysis results. The first stage was determined to be interface reaction controlled (with "Ea" of 53 kJ/mol), while the second and third were determined to be mixed controlled (with "Ea" of 126 kJ/mol and 379 kJ/mol, respectively).

Anahtar Kelimeler

• Nickel
• laterite
• non-isothermal TGA
• kinetic modeling
• Sestak-Berggren equation

Kaynakça

1. [1] Lv X, Lv W, You Z, Lv X, Bai C. Non-isothermal kinetics study on carbothermic reduction of nickel laterite ore. Powder Technol 2018. doi:10.1016/j.powtec.2018.09.061.
2. [2] Li B, Ding Z, Wei Y, Wang H, Yang Y, Barati M. Kinetics of Reduction of Low-Grade Nickel Laterite Ore Using Carbon Monoxide. Metall Mater Trans B Process Metall Mater Process Sci 2018;49:3067–73. doi:10.1007/s11663-018-1367-8.
3. [3] Yang S, Du W, Shi P, Shangguan J, Liu S, Zhou C, et al. Mechanistic and kinetic analysis of Na2so4 -Modified laterite decomposition by thermogravimetry coupled with mass spectrometry. PLoS One 2016. doi:10.1371/journal.pone.0157369.
4. [4] Zhang Y, Cui K, Wang J, Wang X, Qie J, Xu Q, et al. Effects of direct reduction process on the microstructure and reduction characteristics of carbon-bearing nickel laterite ore pellets. Powder Technol 2020. doi:10.1016/j.powtec.2020.08.059.
5. [5] Elliott R, Pickles CA. Thermodynamic Analysis of the Selective Reduction of a Nickeliferous Limonitic Laterite Ore by Hydrogen. High Temp Mater Process 2017. doi:10.1515/htmp-2015-0208.
6. [6] Zhu D, Pan L, Guo Z, Pan J, Zhang F. Utilization of limonitic nickel laterite to produce ferronickel concentrate by the selective reduction-magnetic separation process. Adv Powder Technol 2019;30:451–60. doi:10.1016/j.apt.2018.11.024.
7. [7] Elliott R, Pickles CA, Forster J. Thermodynamics of the Reduction Roasting of Nickeliferous Laterite Ores. J Miner Mater Charact Eng 2016;04:320–46. doi:10.4236/jmmce.2016.46028.
8. [8] Ma Y, Niu R, Wang X, Wang Q, Wang X, Sun X. Co-pyrolysis behaviour and kinetic of two typical solid wastes in China and characterisation of activated carbon prepared from pyrolytic char. Waste Manag Res 2014. doi:10.1177/0734242X14557381.

9. [9] Bartocci P, Tschentscher R, Stensrød RE, Barbanera M, Fantozzi F. Kinetic analysis of digestate slow pyrolysis with the application of the master-plots method and independent parallel reactions scheme. Molecules 2019. doi:10.3390/molecules24091657.
10. [10] Wang Z, Xie T, Ning X, Liu Y, Wang J. Thermal degradation kinetics study of polyvinyl chloride (PVC) sheath for new and aged cables. Waste Manag 2019. doi:10.1016/j.wasman.2019.08.042.
11. [11] Yeo JY, Chin BLF, Tan JK, Loh YS. Comparative studies on the pyrolysis of cellulose, hemicellulose, and lignin based on combined kinetics. J Energy Inst 2019. doi:10.1016/j.joei.2017.12.003.
12. [12] Han J, Sun Y, Guo W, Deng S, Hou C, Qu L, et al. Non-isothermal thermogravimetric analysis of pyrolysis kinetics of four oil shales using Sestak–Berggren method. J Therm Anal Calorim 2019. doi:10.1007/s10973-018-7392-7.
13. [13] Málek J. The kinetic analysis of non-isothermal data. Thermochim Acta 1992. doi:10.1016/0040-6031(92)85118-F.
14. [14] Ceylan S. Kinetic analysis on the non-isothermal degradation of plum stone waste by thermogravimetric analysis and integral Master-Plots method. Waste Manag Res 2015. doi:10.1177/0734242X15574590.
15. [15] Dilmaç N. Isothermal and non-isothermal reduction kinetics of iron ore oxygen carrier by CO: Modelistic and model-free approaches. Fuel 2021. doi:10.1016/j.fuel.2021.120707.
16. [16] Lv X, Lv X, Wang L, Qiu J. Thermal analysis kinetics of the solid-state reduction of nickel laterite ores by carbon. Miner. Met. Mater. Ser., 2017. doi:10.1007/978-3-319-51340-9_15.
17. [17] Zhang Y, Wei W, Yang X, Wei F. Reduction of Fe and Ni in Fe-Ni-O systems. J Min Metall Sect B Metall 2013. doi:10.2298/JMMB120208038Z.
18. [18] Li B, Wang H, Wei YG. Kinetic analysis for non-isothermal solid state reduction of nickel laterite ore by carbon monoxide. Trans Institutions Min Metall Sect C Miner Process Extr Metall 2012;121:178–84. doi:10.1179/1743285512Y.0000000014.
19. [19] Liu Y, Lv X, You Z, Lv X. Kinetics study on non-isothermal carbothermic reduction of nickel laterite ore in presence of Na2SO4. Powder Technol 2020;362:486–92. doi:10.1016/j.powtec.2019.11.103.
20. [20] Pickles CA, Forster J, Elliott R. Thermodynamic analysis of the carbothermic reduction roasting of a nickeliferous limonitic laterite ore. Miner Eng 2014;65:33–40. doi:10.1016/j.mineng.2014.05.006.
21. [21] Janković B, Adnadević B, Mentus S. The kinetic analysis of non-isothermal nickel oxide reduction in hydrogen atmosphere using the invariant kinetic parameters method. Thermochim Acta 2007. doi:10.1016/j.tca.2007.01.033.
22. [22] Janković B, Adnadević B, Mentus S. The kinetic study of temperature-programmed reduction of nickel oxide in hydrogen atmosphere. Chem Eng Sci 2008;63:567–75. doi:10.1016/j.ces.2007.09.043.