Low-Temperature Carbothermic Reduction of Indonesia Nickel Lateritic Ore with Sub-Bituminous Coal
In this work, the experiment was conducted to investigate the effect of temperature and sub-bituminous coal on upgrading nickel laterites ores by carbothermic reduction. The reduction was carried out in the muffle furnace at a temperature ranging of 800-1100 °C. The produced calcine from reduction step was grounded in vibrating mill, mixed with water and passed on a magnetic separator to separate nickel concentrates from the tailing. The experimental results showed that the concentrate with highest nickel grade was produced at temperature 1000 °C. The nickel grade on concentrate was 5.0 %, with the recovery of nickel was 80.6 %.
Upgrading low nickel content laterite ores using selective reduction followed by magnetic separation
Abstract The processing of nickel laterite ore to produce ferronickel is energy intensive, especially when low nickel content ores are processed. The selective reduction–beneficiation of laterite ore to produce high nickel content nickeliferous concentrate and abandon gangue minerals before smelting potentially offers an effective pre-treatment to this process. In this work, the authors conducted selective reduction of nickel laterite ores at 1100 °C for 60 min with addition of 6% calcium sulfate and 5% reductant coal. The reduced ore was then wet magnetic separated. The experiments show that high nickel content nickeliferous concentrate containing 6.0% Ni with nickel recovery of 92.1% could be produced with over 75% of the reduced ore, containing low nickel concentration, rejected. The tests indicated that the selectivity of reduction depends mainly on reduction atmosphere and silica level. According to the microscopic study, nickel oxide had been reduced and nickel was mainly enriched into a γ Fe–Ni phase. The presence of sulfur significantly promoted γ Fe–Ni particle growth, from 5.8 μm to 16.1 μm, and improved the Ni enrichment in metallic phases.
Assessing student learning in higher education
Chapter 1. Introduction to the Text, Chapter 2. What is Assessment?, Chapter 3. Student Learning, Chapter 4. Methods and Strategies: An Overview, Chapter 5. Assessing Essays, Chapter 6. Multiple Choice Questions, Chapter 7. Assessing Practical Work, Chapter 8. Assessing Projects, Chapter 9. Assessing Problems, Chapter 10. Assessing Oral Communication, Chapter 11. Self and Peer Assessment, Chapter 12. Self Assessment: Related Approaches, Chapter 13. Using Computers in Assessment, Chapter 14. Changing Assessment, Chapter 15. Reliability, Validity and Examining, Chapter 16. Quality, Standards and Underlying Issues, Bibliography Notes and comments on activities Some further reading Appendix One: Examples of examination questions in Arts, Law and Social Sciences