| 摘要 |
<p>A process for the removal of contaminants from particulate material. The process includes the steps of feeding a feedstock of the particulate material through a series of treatment stages in which it is contacted with a washing liquid and then separated from the washing liquid. Washing liquid removed from at least one of the treatment stages is passed to the stage previously encountered by the feedstock and the feedstock and washing liquid are passed in opposite senses or countercurrent fashion with respect to adjacent stages. The treatment stages include a first extractant treatment stage in which a first extractant solution is employed to dissolve contaminants of a first kind and a second extractant treatment stage in which a second extractant treatment solution is employed to dissolve contaminants of a second kind.</p> |
