Attapulgite-Polysulfide Composite for Highly Selective, Scalable Recovery of Precious Metals from Gold Ore Residues and Wastewater

Abstract

Precious metals play a crucial role in a multitude of sectors, owing to their superior physicochemical attributes, yet their limited natural abundance leads to supply shortages. Consequently, it is imperative to devise an affordable adsorbent capable of effectively extracting gold from dilute gold ore tailings and industrial effluents. This study delineates an economical approach to fabricating a composite sorbent, integrating attapulgite with a sulfur-rich polymer. The polymer (named as Poly(S-AM) or IV polymer) was synthesized through inverse vulcanization by utilizing elemental sulfur (S₈) and acrylamide (AM), both cost-effective and readily accessible. This Poly(S-AM) was then merged with acid-modified attapulgite (HATP) via a mechanochemical process, giving the Poly(S-AM)/HATP composite. With Au(III) serving as a representative ion, the composite achieved a peak adsorption capacity of 964.15 mg/g, demonstrating a selectivity greater than 98% for Au(III) and Ag(I) in gold ore tailings and wastewater. Notably, the material maintained over 80.14% of its Au(III) adsorption capability after seven regeneration cycles. A scaled-up continuous adsorption cyclic trial was performed using 1 kg of gold mine wastewater, with the results indicating that after one cycle, the adsorption rates reached as high as 78.12% for Au(III) and 97.69% for Ag(I). The integration of HATP not only curtails the overall cost but also enhances the material's dispersibility, acid resistance and recyclability, without diminishing its adsorption efficacy. These findings highlight the composite's strong economic feasibility and application potential, offering a promising route for efficient precious-metal recovery and valueadded utilization of IV polymers.