Experimental Study On Comprehensive Recovery Of Valuable Metals From Weathered Clay-type Niobium Or

Niobium as a refractory rare metal is widely used in the aerospace,nuclear industry,military,automotive industry,construction,metallurgy,and other fields,is an indispensable material for scientific and technological development.The Universal characteristics of niobium in the world that complex mineral composition,low metal content,complex symbiosis,fine-grained dissemination,which lead to low grade and recovery of niobium concentrate and waste of niobium resources.At present,China is short of systematic beneficiation research of pyrochlore,as a result,there is great significance in improving the comprehensive utilization of niobium resources by exploring technological processes and reagent systems for improving the grade and recovery of niobium concentrate.In this paper,weathered clay type niobium ore is the object of study,the mineral properties of valuable elements niobium,iron,and phosphorus in the ore were found through process mineralogy research,the valuable elements in the ore were comprehensively recovered by the combined process flow of beneficiation and metallurgy of"pre-desliming-magnetic separation recovery of iron-flotation recovery of phosphorus-flotation recovery of niobium-wet leaching".Process mineralogy study shows that in this niobium ore the valuable elements with recovery value are Nb₂O₅,Fe,and P₂O₅,with contents of 0.72%,13.03%,and 6.48%,respectively,main recoverable minerals are pyrochlore,magnetite,and apatite,and gangue minerals are mainly silicate minerals such as quartz,potassium feldspar,kaolinite,muscovite and other silicate minerals.The gangue elements are Ca,Mg,Si,and S.The analysis of magnetic characteristics shows that the pyrochlore in the ore has different degrees of weak magnetism due to long-term weathering and iron staining.The degree of mineral liberation measurement of pyrochlore shows that the liberation degree of pyrochlore in raw ore was 88.34%,and the liberation degree of pyrochlore below 0.15mm could reach more than 90%,the productivity of materials below 0.01mm is higher,but the distribution of Nb₂O₅is low.The spiral chute was selected to remove primary mud,feeding size was-2mm,the feeding concentration was 30%,the secondary mud was removed by shaking table,and the feeding size is-0.15mm,after the two stages of desliming,81.53%fine mud was removed from the raw ore,the grade and recovery of Nb₂O₅was 2.73%and 68.89%,the grade and recovery of P₂O₅was18.57%and 53.03%,the grade and recovery of Fe was 22.56%and 31.91%respectively in the obtained coarse concentrate.Through the magnetic separation test,the optimal magnetic field intensity of roughing was determined to be 0.25T and the optimal magnetic field intensity of cleaning was 0.2T,through"one roughing and one cleaning"low-intensity magnetic separation finally gets the iron concentrate with operating productivity of 19.42%,Fe grade of 63.34%,the grade of Nb₂O₅was 3.33%and P₂O₅was 22.91%in tailings of removal iron.Through single factor test and orthogonal test,the best reagent system of phosphorus roughing from magnetic separation tailings:sodium carbonate 600g/t,sodium silicate 800g/t,and GY-10450g/t.Phosphorus concentrate with a grade of 42.83%,operating recovery of P₂O₅was 86.44,grade of Nb₂O₅was 0.25%,grade of Fe was 3.78%was obtained by a closed-circuit process of"one roughing,one scavenging,one cleaning",the grade of Nb₂O₅was 5.96%and operating recovery was 96.57%in tailings.After concentration and dehydration of flotation phosphorus tailings,a niobium flotation test was carried out to determine the reagent system of niobium roughing:CS+CH 2500+2500 g/t,FB+FC 150+450 g/t,the reagent system of niobium cleaning:CS+CH1200+1200g/t,under these conditions,can get the niobium concentrate with a grade of Nb₂O₅was 43.26%,operating recovery of Nb₂O₅was 93.93%,grade of P₂O₅was 2.72%,grade of Fe was 16.86%was obtained by a closed-circuit process of"one roughing,four scavengings,four cleanings".The raw ore was separated by the closed-circuit process of gravity separation-magnetic separation-flotation was adopted,which was"pre-desliming,magnetic separation recovery of iron,flotation recovery of phosphorus,flotation recovery of niobium",the final technical indexes are as follows:Grade of Nb₂O₅in niobium concentrate was 43.20%,recovery was 61.41%,the grade of P₂O₅in phosphorus concentrate was 42.84%and the recovery was45.31%,the Fe grade of iron concentrate was 63.28%and the recovery was 17.34%.The optimum leaching conditions of wet dephosphorization of niobium concentrate:acid concentration 40%,liquid-solid ratio 3∶1,leaching time 15min.Under these conditions,the leaching rate of P₂O₅and Fe reached 88.52%and 66.04%respectively,the grade of Nb₂O₅increased to 47.92%and P₂O₅was 0.35%in niobium concentrate.In this study,the combined process of“gravity separation-magnetic separation-flotation-leaching”was finally adopted to obtain high-quality niobium concentrate,which provided a new idea for the research on the beneficiation of pyrochlore as the bearing of niobium.