A Vidyadhar

Stratification and segregation features of pulverized electronic waste in flowing film concentration

Gravity separation of metals from plastics in pulverized e-waste using flowing film concentration in a shaking table was investigated. Over 51% rejection of plastics in a single stage operation was achieved under optimum conditions. The shaking table was shown to be suitable for processing ground PCBs. Pulverized e-waste containing 22% metals was enriched to around 40% metals in a single pass. Statistical models for the mass yield of metal-rich stream and its grade were developed by design of experiments. Optimization was carried out to maximize the mass yield at a target product grade and preferred operating regimes were established. Experiments were designed to prevent metal loss and over 95% recovery values were obtained under all conditions. Settling distances of metals and plastics were computed and shown to be good indicators of separation performance. Particle morphology and stratification in the troughs in between the riffles were shown to influence the separation significantly. Water flow-assisted motion of the plastics was captured and its role in determining the effectiveness of separation was described. The efficacy of tabling was well established for treating ground PCBs. The wet process was shown to be environment friendly and sustainable. It is also relatively cheap and has good potential for industrial application. However, rigorous cost estimates will be required before commercial application.

A Novel Beneficiation Scheme for A Medium Coking Coal Fines from India

Beneficiation strategy for a medium coking coal fines from India has been studied. These coal fines have good washability characteristics indicating about 60% yield at 14% ash in clean coal. But the release analysis results indicate poor flotability of these fines. Only about 30% yield was achievable at 14% ash in the clean coal. Various schemes for flotation including two-stage flotation, split flotation, spiral, and a combination of spiral and flotation were studied using a 15-cm diameter Jameson Cell. Combination of spiral and Jameson Cell flotation achieved approximately 69% yield at 17.5% ash.

Study of cut point density and process performance of Floatex density separator in fine coal cleaning

ABSTRACT Advanced gravity separation of a high-ash (36%) semi-coking coal in a Floatex density separator (FDS) is investigated. The influence of the operating variables on the separation features has been identified. It is established that a higher bed pressure and a higher teeter water flow rate enhance the mass yield of the clean coal albeit with a poorer grade. A higher bed pressure reduces the bed voidage leading to a higher cut point density. Although bed voidage is reduced due to higher teeter water rate, the hydraulic transport increases significantly. A higher pulp density and a higher feed rate introduce severe hindered settling conditions leading to an increase in the cut point density. This results in a poorer product grade with a higher yield. The optimum condition for 23% product ash in a single-stage operation is identified. The yield at the optimum condition is found to be 64.3% which is close to the theoretical maximum for this coal. The dependence of the cut point density as well as Ecart probable (Ep) value on the operating variables is quantified. A specific gravity of separation of below 1.8 and an Ep value of around 0.15 is achievable under controlled operation of the FDS.