Sequential extractions of lanthanide elements and toxic metals associated with rare earth phosphate-type minerals

Abstract

The elements of economic interest in coastal sediments are characterized by a relative high concentration in minerals as the ilmenite, rutile, monazite and manganite. The objective of this work has been to carry out a study of selective sequential extractions of lanthanide elements and metals that are toxic. It started with rare earth phosphate-type minerals, using the technology established in the American continent (Tessier), applicable to sludge and sediments. The study is concerned with the outcrops of REE's minerals reported in Mexico as pegmatite, in the settlement "The Dead”, Telixtlahuaca, Oaxaca and of “Lagoon Mother” and “Saw of San Carlos”, Tamaulipas. There were evaluated in addition samples of Cuarzomonzodiorite, of “The Incarnation”, Hidalgo. Two modifications interfere to the above mentioned scheme of extractions and for the reached results it was possible to find the existence of some elements lanthanides as well as of toxic metals, praseodymium, neodymium, ytterbium and lead, associated with these minerals. The procedure of sequential selective extractions according to Tessier's methodology, does not manage to extract significant quantities of these elements, except in the conditions of maximum aggressiveness, of a digestion with HNO3/HClO4 concentrates and warming.