Study on Improving Tungsten-Molybdenum Loading Capacity of Deactivated Alkaline Extraction Organic Phase Using Ion Exchange AITranslate

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Chinese Library Classification Number:TF841.1[冶金工程]

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To improve the tungsten-molybdenum loading capacity of the deactivated organic phase(with N263 as the extractant)in the alkaline extraction section during the preparation of ammonium paratungstate from low-grade complex scheelite,this study adopted the ion exchange method and employed NaCl solution as the ion exchanger to remove harmful anions from the organic phase.The effects of NaCl solution concentration,O/A phase ratio,reaction temperature,single ion exchange duration and the number of ion exchange cycles on the tungsten-molybdenum loading capacity of the organic phase were systematically investigated through single-factor experiments.Furthermore,through counter-current extraction-washingstripping experiments,the tungsten and molybdenum extraction rates of the organic phase after NaCl ion exchange and NH₄HCO₃ conversion were explored,along with an assessment of whether the raffinate and stripping solution meet the requirements of industrial production.The results of single-factor experiments show that the optimal conditions for treating the deactivated alkaline extraction organic phase by the NaCl ion exchange method are as follows:NaCl concentration of 3 mol/L,O/A phase ratio of 1∶1,reaction temperature of 35℃,single ion exchange duration of 3 min,and 7 ion exchange cycles.After the organic phase obtained under these optimal conditions is converted with NH₄HCO₃,its WO₃ loading capacity is increased by 85.49%and Mo loading capacity by 72.56%,compared with those of the deactivated alkaline extraction organic phase.Under the conditions where the O/A phase ratios for extraction,washing,and stripping are 1∶2,1∶0.35,and 1∶2.6 respectively,and other parameters remain consistent with the current industrial production conditions,a comparison of the tungsten-molybdenum extraction performances of different organic phases after 6-stage counter-current extraction,4-stage washing,and 10-stage stripping experiments shows that the organic phase modified by NaCl ion exchange-NH₄HCO₃ conversion achieves extraction rates of 92.12%for WO₃ and 95.31%for Mo.Although these rates remain lower than those of the freshly prepared alkaline extraction organic phase,they increase by 42.46%and 40.08%respectively compared with the deactivated alkaline extraction organic phase without NaCl ion exchange treatment.Its tungstenmolybdenum loading capacity meets the requirements of industrial production,which breaks the restriction of the alkaline extraction section on production output during the preparation of ammonium paratungstate from low-grade complex scheelite.Various indexes of the raffinate and stripping solution obtained after extraction and stripping of the organic phase modified by NaCl ion exchange-NH₄HCO₃ conversion all meet the industrial production requirements.The increased tungsten content in the stripping solution reduces the evaporation energy consumption of the subsequent APT crystallization section,while the decreased tungsten content in the raffinate improves the direct recovery rate of the extraction section.Therefore,the NaCl ion exchange treatment of the deactivated organic phase can effectively reduce the production cost.