Removal of heavy metals by solvent extraction and supported solvent extraction during a recrystallization step in the phosphoric acid production process

C. Koopman*, G. J. Witkamp

*Corresponding author for this work

Research output: Contribution to conferencePaperpeer-review

Abstract

During the production of phosphoric acid from phosphate ore and sulfuric acid, large amounts of calcium sulfate are formed, in which impurities from the feedstock are incorporated. To use the calcium sulfate in, for example, the building industry, a lower concentration of impurities is desired. Mercury, copper, lead, and cadmium were extracted from clear industrial recrystallization acid (0.8-3.9 mol/kg H3PO4, 0.2-0.5 mol/kg H2SO4) by supported solvent extraction with the extracting agent Cyanex 302 in kerosene in a transverse flow hollow fiber module. The permeability for the mercury ion was 1.4·10-6 m/s, whereas that for the copper ion was calculated to be 1.5·10-6 m/s. Cadmium, lead, and copper were extracted during the recrystallization of calcium sulfate hemihydrate to dihydrate, an existing step within the phosphoric acid production process, by solvent extraction with the same extracting agent. The concentrations of cadmium and zinc in the newly formed calcium sulfate were proven to be decreased. Unfortunately, concentrations of mercury and lead were too low for analysis.

Original languageEnglish (US)
Pages327-335
Number of pages9
StatePublished - Dec 1 1999
Externally publishedYes
EventMetal Separation Technology Beyond 2000: Integrating Novel Chemistry with Processing - Oahu, HI, USA
Duration: Jun 13 1999Jun 18 1999

Conference

ConferenceMetal Separation Technology Beyond 2000: Integrating Novel Chemistry with Processing
CityOahu, HI, USA
Period06/13/9906/18/99

ASJC Scopus subject areas

  • Engineering(all)

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