Precious metals adsorption and extraction using functional mesoporous adsorbents

The development and application of high capacity heavy metal ion adsorbents with uniform nanoscale porosity (denoted MP-HMS) to extract precious metals from mine effluent is described. Recent reports have demonstrated the use of mesoporous materials for the extraction of precious metals from ultra-low concentrations. Although current mining processes are able to recuperate the majority of the precious metals from ore bodies, it is speculated that significant amounts of these elements may, in some instances, be discharged as soluble ions into mine effluent streams.; The adsorbents are selective towards precious metals ions such as those of gold, platinum and palladium. The adsorption capacities of these materials are also among the highest reported. MP-HMS has shown the capability to adsorb 330 mg gold per gram from a solution of gold (up to 30% of their weight). The adsorbent was found to be extremely effective in adsorbing gold ions from low level solutions. Experimental studies indicated that MP-HMS maximum adsorption of gold (99.9%) occurred under all solution concentrations. Another promising attribute of these materials is their favourable adsorption kinetics. The contact time required for 80% adsorption of gold was found to be less than 60 seconds. The efficacy of these new materials for the recovery of PMs from mining effluent is thus evaluated and their prospect for application in the mining industry is discussed.