Hydrogen Reduction Process for Bayan Obo Niobium Concentrate
The occurrence state of key elements of niobium,rare earths,and titanium in Bayan Obo niobium concentrate samples was characterized before and after hydrogen reduction,and effect of hydrogen reduction condition on iron metallization rate was also explored.After 90 min reduction with flow rate of hydrogen at 300 mL/min,and reduction temperatures of 800℃,850℃,900℃,950℃,1000℃,and 1050℃respectively,the corresponding metallization rates are 89.22%,85.79%,82.50%,80.52%,72.15%,and 70.64%.It is found that during hydrogen reduction process,most of iron minerals can be reduced to metallic iron,but with temperature rise,the reduction rate of iron minerals decreases due to effect of mineral powder bonding.Niobite,as the main niobium-containing phase,is easily reduced,while aeschynite and niobium-iron rutile are difficult to be reduced;bastnasite,the main rare earth-containing phase,doesn't change,while monazite can undergo thermal decomposition at 1 050℃;ilmenite,niobium-iron rutile and aeschynite,as the main titanium-containing phases,are difficult to be reduced.
Bayan Obo depositniobiumhydrogen reductionphase transitionrare earthniobiteilmenite
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