Leaching of Trace Amounts of Metals from Flotation Tailings in Cupric Chloride Solutions

Abstract

With decreasing ore grades, the tailings of mining operations are becoming of increasing interest as metal-containing secondary raw materials. The objective of the current work was to investigate chloride leaching of gold, copper, cobalt, nickel, and zinc present in the flotation tailings. In the current study, the effect of cupric ion as an oxidant (0-50 g/L) and NaCl (150-250 g/L) on metals extraction was investigated. The other parameters, such as pH (1.8), temperature (95°C), solid/liquid ratio (25%), oxygen feed rate (1200 mL/min), leaching time (24 h), and stirring rate (950 rpm), were kept constant. Gold dissolution rate was shown to increase with increase in cupric ion concentrations up to 50 g/L. Also, increase in NaCl concentration up to 250 g/L increased gold extraction. Majority of the copper present in the flotation tailings could be dissolved with all the all solutions investigated. The other base metals, cobalt, nickel, and zinc extractions were also shown to increase with increase in the cupric ion and sodium chloride concentration. However, even in the absence of cupric ion addition (t = 72 h, 250 g/L NaCl), the final extraction of Cu, Ni, Zn, Co, and Fe increased up to 98, 93, 83, 76, and 80%, respectively. This shows the power of inherently originating oxidants present in the tailings. Furthermore, the solid analysis of the leach residue indicated that leaching the flotation tailings in pure NaCl may result in partial gold dissolution. The results demonstrate that significant amount of metals present in the tailings could be extracted even with only NaCl as added chemical in the presence of oxygen feed, oxidizing agents originating directly from the raw material. This can provide an advantageous cyanide-free method for extraction of metals from very low-grade tailings with low chemical consumption.

Leaching of Cu, Zn, and Pb from Sulfidic Tailings Under the Use of Sulfuric Acid and Chloride Solutions

“…Mining activities generate large amounts of solid wastes that are usually stored long term under dam facilities [5]. These tailings can still contain valuable metals, such as copper, zinc, nickel, and gold, as well as hazardous elements, such as lead and arsenic [6]. Besides all this, there is an environmental risk associated with the liberation of toxic elements to the soil and groundwater, with the generation of acid mine drainage [7], and also the disposal of waste on-site, such as dam failures [8].…”

Mechanism of selective gold extraction from multi-metal chloride solutions by electrodeposition-redox replacement

“…15,16 Chloride-based processes of gold leaching have proven their efficiency and are considered a viable alternative to conventional hydrometallurgical technologies. 17,18 The efficient extraction of gold in aqueous chloride solutions is possible even with minor reagent addition. 19 However, in some regions of the world, water is viewed as a critical resource, and reducing its consumption is one of key requirements for a sustainable development.…”

Performance-Based Selection of the Cathode Material for the Electrodeposition-Redox Replacement Process of Gold Recovery from Chloride Solutions

“…The composition of the solution, as well as its pH and redox potential (Table II), is typical for such a process. [37][38][39] Solution samples were analyzed by inductively coupled plasma-optical emission spectroscopy (ICP-OES; Thermo Scientific iCap 6000), and the gold content was additionally measured by mass-spectrometry (ICP-MS; Thermo Scientific iCap Q).…”