Utilization of gold-bearing and iron-rich pyrite cinder via a chlorination–volatilization process

Abstract

The chlorination−volatilization process has been adopted to make full use of gold-bearing and iron-rich pyrite cinder. However, problems of low recovery rate, pulverization of pellets, and ring formation have been encountered during the industrialization of this process. The effects of various parameters on the volatilization rates of valuable metals and on the compressive strength of roasted pellets were investigated in this paper. The parameters include the CaCl₂ dosage, heating temperature, and holding time. The results show that heating temperature is the most important parameter for the recovery of target metals. More CaCl₂ was needed for the recovery of zinc than for the recovery of gold, silver, and lead. CaCl₂ started to react with sulfides/SO₂/SiO₂ at temperatures below the melting point of CaCl₂ to generate Cl₂/HCl. Gaseous CaCl₂ was formed at higher temperatures and could react with any of the components. The compressive strength of roasted CaCl₂-bearing pellets first decreased slowly with increasing temperature at temperatures lower than 873 K, which could result in the pulverization of pellets during heating. Their compressive strength increased dramatically with increasing temperature at temperatures greater than 1273 K. Certain quantities of CaCl₂ and Fe(II) could improve the compressive strength of the roasted pellets; however, the addition of excessive CaCl₂ decreased the compressive strength of pellets.

Keywords

pyrite cinder / gold / chlorination / oxidized pellets / compressive strength

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