Development of a new hydrometallurgical process for Indonesian copper sulphide

Imelda Eva Roturena Hutabarat

Research output: ThesisDoctoral Thesis

Abstract

The development of extracting processes through hydrometallurgy for copper sulphide minerals is becoming one of the most promising fields not only for copper production, but also for by-product metal production. The advantage compared to existing pyrometallurgical processes is the selective extraction that allows chosen metals to be extracted. The goal of this study is to develop a process flowsheet for extracting copper and other important metals from the Indonesian copper concentrates by using an alternative new hydrometallurgy process to increase the value of the minerals. These copper concentrates, with the mineralogical composition of chalcopyrite and pyrite, contain various metals in several oxidation states. They are classified as both precious and critical metals due to their scarcity. However, the content of the precious and critical metals are relatively low and hidden in the complex minerals. In order to prepare these concentrates for the leaching process, the characterisation of the metals and the investigation of a suitable temperature for the pre-treatment process are the most important steps. The characterisation methods include chemical analysis by X-ray fluorescence spectroscopy (XRF), inductively coupled plasma mass spectrometry (ICP-MS) and X-ray diffraction (XRD) for the mineralogical phases. The thermal behaviour was investigated by simultaneous thermal analysis consisting of differential scanning calorimetry (DSC) in combination with thermogravimetry (TG) and Fourier transform infrared (FTIR) spectroscopy. Samples were pre-treated by roasting at the several temperature transitions and subsequently characterised by XRD and scanning electron microscopy with energy dispersive spectroscopy (SEM-EDS). Furthermore, chloride leaching experiments using design of experiments by Modde® 9.0 were performed with roasted concentrates as a result of a thermal behaviour study to analyse the optimum parameters and concentrations of the most important metal extractions. Through the analyses the key factors for a consistent condition supporting the thermodynamic conditions are the pH and electrochemical potential (ORP). The concentrations of sodium hypochlorite (NaOCl), acid chloride (HCl) and sodium chloride (NaCl) are important to maintain the key factors to reach the required parameters. As the oxidation agent in the chloride/hypochlorite system, hypochlorous acid should be formed with NaOCl in acidic condition, which is the most effective oxidising agent. The pH and ORP values confirm that gold, palladium and bismuth all depend on the ORP and gold and palladium on the pH, as well. The key factors from the experiment results and process parameters including the concentration of the solution for an optimum extraction process are summarised in a hydrometallurgical process flow chart for Indonesian copper sulphide.
Translated title of the contributionEntwicklung neuer hydrometallurgischer Verfahren für indonesisches Kupfersulfid
Original languageEnglish
QualificationDr.mont.
Supervisors/Advisors
  • Flachberger, Helmut, Assessor B (internal)
  • Antrekowitsch, Helmut, Assessor A (internal)
Publication statusPublished - 2016

Bibliographical note

embargoed until null

Keywords

  • copper
  • thermal behavior
  • leaching
  • chloride/hypochlorite
  • flowsheet process

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