Reduction crystallization of heavy metals from acid treated phosphogypsum effluent utilizing hydrazine as a reducing reagent

Tebogo Mashifan, Nastassia Sithole

Research output: Contribution to journalConference articlepeer-review

1 Citation (Scopus)


Phosphogypsum is a by-product generated from phosphoric acid production processes. Due to the negative impact posed to the environment by the material, a chemical treatment process was developed to reduce the hazardous constituents in the material and render the final product useful for other applications. The treatment of phosphogypsum produced an effluent laden with contaminants such as copper, iron, manganese and thallium. This study was conducted to investigate the use of hydrazine as a reducing agent to remove and reduce Cu, Fe, Mn and TI from effluent, applying a reduction crystallization process. Nickel powder a base substrate was utilised as a seeding material. A feasibility study was carried out to test the efficiency and find the optimum operating conditions for the process. The predominant detected components in the feedstock were 71% Fe, 14% Tl, 5.1% Mn, 4.12% Cu and 2.4% Zn. The results obtained indicate that hydrazine can effectively remove up to 99.8% of metals from the effluent at the optimum pH of 10.5. Growth of the nickel powder particles was evident indicating a reduction and adsorption of contaminants on the surface of the powder. The treated solution was within South African acceptable limits for effluent discharge, which stipulates a concentration of 20 mg/l of copper, iron, manganese and thulium.

Original languageEnglish
Article number01002
JournalE3S Web of Conferences
Publication statusPublished - 28 May 2019
Event2018 6th International Conference on Environment Pollution and Prevention, ICEPP 2018 - Brisbane, Australia
Duration: 6 Dec 20188 Dec 2018

ASJC Scopus subject areas

  • General Environmental Science
  • General Energy
  • General Earth and Planetary Sciences


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