Concentration and Recovery of Valuable Heavy Minerals from Dredged Fine Aggregate Waste

Abstract

Inside the finest fractions of aggregates, usually wasted by ready mix concrete companies, valuable heavy minerals content is substantial. The concentration and recovery of valuable heavy minerals contained in dredged fine aggregates waste, located in Pyeongtaek South Korea, were investigated to develop a process that can recover and concentrate most of each heavy mineral. The raw material contains ilmenite, magnetite, monazite, and zircon. A gravity separation, recirculating the middlings recovered ilmenite, magnetite, monazite, and zircon with 44.05%, 36.90%, 53.76%, and 69.7% respectively. Nevertheless, a magnetic separation followed by gravity separation of the non-magnetic fraction further improved the recovery of ilmenite, magnetite, monazite, and zircon to 86.96%, 85.09%, 91.06%, and 90.82% respectively. This concentrate was separated at different magnetic intensities. Magnetite was concentrated at 0.05 T, resulting in a recovery of 23.4% and grade of 95.1 wt%. Ilmenite was at 0.4 T, with a recovery of 55.2% and grade of 84.2 wt%. Monazite was at 0.9 T, with a recovery of 59.3% and rare earth oxide content of 45.2%, the non-magnetic fraction has a high zircon content, the recovery was 70.6% and grade of 91.8 wt%.

Physical beneficiation of heavy minerals – Part 1: A state of the art literature review on gravity concentration techniques

“…It is imperative to note that the different gravity separation methods may be classified into conventional gravity concentrations (CGC) which involves the use of spirals, jigs, shaking tables, dense media separators, and the enhanced gravity concentrations (EGC), such as: Falcon, Knelson, Kelsey jigs, Mozley multi gravity concentrators [ 21 , 55 , [92] , [93] , [94] , [95] ]. The CGC processes have been reported inefficient in the beneficiation of fine/ultra-fine mineral particles, especially in their selectivity and mineral recovery [ 87 , 92 , 95 , 96 ], hence development and adoption of EGC.…”

“…were designed to give a more effective/efficient beneficiation at a high throughput while reducing the limiting particle size factor of the CGC [ 56 , 67 , 77 , 108 , 113 , 114 ]. Recent literature have reported CGC to have high efficiency on coarser HM particles and the EGC to have a limitation/difficulty in concentrating coarser particles, thus less effective on coarse HM particles of higher particle sizes [ 87 , 96 ]. It was also reported [ 115 , 116 ] that the EGC was essentially developed and applicable for the efficiency of the beneficiation and recovery of fine minerals or particulates.…”

Recovery of valuable heavy minerals via gravity and magnetic separation operations from Diit Quaternary stream sediments, southern coast of the Red Sea, Egypt

“…Then followed by the stage of magnetic separation of the obtained HMC, in order to separate ferromagnetic from paramagnetic and from diamagnetic heavy minerals. [18][19][20] It is necessary to evaluate the gravity concentration process in terms of whether it is possible or not, so the concentration criterion (CC) is commonly used for this purpose. A concentration criterion (CC) can be defined as;…”