Leaching isomorphism rare earths from phosphorite ore by sulfuric acid and phosphoric acid.
Leaching isomorphism rare earths from phosphorite ore by sulfuric acid and phosphoric acid.
复制标题
硫酸、磷酸从磷矿矿中浸出同象稀土
DOI：
10.1007/s12598-017-0952-3
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发表时间：
2017
期刊：
影响因子：
8.8
通讯作者：
谢红艳
中科院分区：
文献类型：
--
作者：
金会心;吴复忠;毛小浩;王眉龙;谢红艳
世界上大多数磷块岩矿床都含有类质同象稀土，在湿法磷酸工艺中，稀土很难被浸出。本文对硫酸、磷酸、混合酸及磷酸硫酸两步浸出法浸出稀土进行了系统的研究。目的是阐明抑制稀土浸出的主要因素，并为湿法磷酸溶液中稀土的进一步富集提供见解。结果表明，H2SO4不是浸出磷矿石中类质同象稀土的有效酸，磷石膏（PG）对稀土的共晶包裹以及稀土硫酸盐或磷酸盐对稀土的沉淀是造成稀土浸出率低的主要原因。高浓度的H_3PO_4能促进稀土离子的溶解和扩散。因此，提高稀土浸出率的最佳浸出方式是先用高浓度的H3PO4溶液充分溶解磷矿，然后加入H2SO4使PG结晶，PG在本体溶液中结晶而不是在固相反应物界面上结晶，从而降低了PG共结晶或包裹对稀土的影响。采用优化的浸出方式，稀土浸出率可达65%。
Most of the phosphorite deposits in the world contain isomorphism rare earths(RE) which are considerably difficult to be leached into solution in the wet phosphoric acid process. In this work, a systematic study of leaching RE using sulfuric acid, phosphoric acid, mixed acid and two-step leaching of phosphoric acid and sulfuric acid was performed. The aims are to illuminate the main factors that inhibit RE leaching and to provide insights into the further enrichment of RE in the wet phosphoric acid solution. The results indicate that H_2SO_4 is not an effective acid for leaching isomorphism RE from phosphorite ore.The low RE leaching efficiency attributes to the RE cocrystallized and encapsulated by phosphogypsum(PG) as well as the precipitation of RE by RE sulfates or phosphates. High concentration of H_3PO_4 can enhance the dissolution and diffusion of RE ions. Hence, the optimized leaching mode of improving RE leaching efficiency is to adequately dissolve phosphorite ores in high concentration of H_3PO_4 solution and then add H_2SO_4 to crystallize PG.The effect of co-crystallization or encapsulation of PG on RE can be decreased due to the crystallizing mode of PG in the bulk solution instead of on the interface of solid reactants. RE leaching efficiency can be high up to 65% by the optimized leaching mode.