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磷酸盐岩中含有1%的镧系元素(稀土)氧化物,它们在矿石中以类质同晶取代Ca~(2+)的形式存在。镧、铈、镨和钕约占总量的80%。前矿石用H_2SO_4浸出时,大部份镧系元素(约70%)损失在石膏残渣中,当矿石用HNO_3或HCl浸出时,不影响肥料的生产,镧系元素的回收串可大于80%。在年产1.3亿吨的矿石中,磷酸盐岩是镧系元素的重要来源。本文将对各种回收方法作一评述。
Phosphates contain 1% lanthanide (rare earth) oxides, which are present in the ore as isomorphously substituted Ca ~ (2+). Lanthanum, cerium, praseodymium and neodymium account for about 80% of the total. Most of the lanthanides (about 70%) are lost in the gypsum residue when the ore is leached with H_2SO_4. When the ore is leached with HNO_3 or HCl, the production of fertilizers is not affected, and the recovery of lanthanides can be greater than 80%. Phosphate rocks are an important source of lanthanides among the 130 million tons of ore each year. This article will make a comment on various recycling methods.