Resin-in-pulp (RIP) technology was developed for the recovery of valuable metals from high volumes of low grade pulps, as is the case with gold processing. More recently, the application of this technology has been evaluated for the recovery of soluble losses of valuable metals from solid residues in base metal plants. For this type of application, the RIP process will improve overall plant recoveries, especially where solid- liquid separation proves difficult as a result of poor filterability or settling characteristics of the solids. An added benefit of the RIP process is a reduction in the environmental impact of the solid residues contaminated with entrained base metals from the plant. Mintek investigated the metallurgical and economic feasibility of using RIP technology for the recovery of soluble cobalt, nickel and copper from thickener underflows on behalf of Anglovaal Mining. Laboratory and mini- plant investigations included the recovery of copper with RIP, followed by simultaneous nickel and cobalt recovery using a second RIP circuit. Recovery of copper, nickel and cobalt in a single RIP circuit was also investigated.