Reaction mechanisms of low-grade molybdenum concentrate during calcification roasting process

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• 作者：Min GAN ; Xiao-hui FAN ; ^{csufanxiaohui@126.com} ; Xu-ling CHEN ; Cheng-qian WU ; Zhi-yun JI ; Song-rong WANG ; Guo-jing WANG ; Guan-zhou QIU ; Tao JIANG
• 关键词：molybdenum concentrate ; calcification roasting ; reaction mechanism ; thermodynamic analysis ; phase transformation
• 刊名：Transactions of Nonferrous Metals Society of China
• 出版年：2016
• 出版时间：November 2016
• 年：2016
• 卷：26
• 期：11
• 页码：3015-3023
• 全文大小：1828 K
• 卷排序：26

文摘

The effects of Ca-based additives on roasting properties of low-grade molybdenum concentrate were studied. The results show that calcium-based additives can react with molybdenum concentrate to form CaSO4 and CaMoO4. The initial oxidation temperature of MoS2 is 450 °C, while the formation of CaMoO4 and CaSO4 occurs above 500 °C. The whole calcification reactions are nearly completed between 600 and 650 °C. However, raising the temperature further helps for the formation of CaMoO4 but is disadvantageous to sulfur fixing rate and molybdenum retention rate. Calcification efficiency of Ca-based additives follows the order: Ca(OH)2>CaO>CaCO3. With increasing the dosage of Ca(OH)2, the molybdenum retention rate and sulfur-fixing rate rise, but excessive dosages would consume more acid during leaching process. The appropriate mass ratio of Ca(OH)2 to molybdenum concentrate is 1:1. When roasted at 650 °C for 90 min, the molybdenum retention rate and the sulfur-fixing rate of low-grade molybdenum concentrate reach 100% and 92.92%, respectively, and the dissolution rate of molybdenum achieves 99.12% with calcines being leached by sulphuric acid.