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Pre-treatment, Concentration, and Enrichment of Precious Metals from Urban Mine Resources
Published in Sadia Ilyas, Hyunjung Kim, Rajiv Ranjan Srivastava, Sustainable Urban Mining of Precious Metals, 2021
Hyunjung Kim, Sadia Ilyas, Rajiv Ranjan Srivastava
An eddy current separator uses a powerful magnetic field to separate nonferrous metals from waste after all ferrous metals have been removed previously by some arrangement of magnets. The device makes use of eddy currents to effect separation. Eddy current separators are not designed to sort ferrous metals, which become hot inside the eddy current field. This can cause damage to the eddy current separator unit belt. The eddy current separator is applied to a conveyor belt carrying a thin layer of e-waste. Nonferrous metals are thrown forward from the belt into a product bin, while nonmetals simply fall off the belt due to gravity. The eddy current separator uses a rotating drum with a permanent/electro- magnet. It produces high-frequency alternating magnetic fields on a magnetic roller; if conductive NMF goes through the magnetic field, it will produce induced current, and if this induced current produces a magnetic field opposite to the original magnetic field, then the NMF (i.e., Al, Cu, etc.) will fly ahead in the direction in which it is moving by repulsive force of the magnetic field; hence, nonferrous metals are separated from other nonmetallic fractions (plastics).
Post-Consumer Waste Production and Utilization
Published in Sehliselo Ndlovu, Geoffrey S. Simate, Elias Matinde, Waste Production and Utilization in the Metal Extraction Industry, 2017
Sehliselo Ndlovu, Geoffrey S. Simate, Elias Matinde
At the scrap pretreatment plant, different types of metals are separated and then shredded into fist-size pieces (Villanueva et al., 2010). The fist-size pieces of various materials are then sorted out into ferrous and non-ferrous materials by means of magnetic separation (Muchová and Eder, 2010b; Villanueva et al., 2010). After magnetic separation, the non-ferrous metals, stainless steel scrap and non-metal fractions are further separated by using combinations of density and eddy current separators (Muchová and Eder, 2010b). For example, fluids with different densities may be used to separate the light metals from the heavy metals. The heavy metals that usually contain mixtures of copper, zinc, lead and stainless steel may be manually hand-picked or sorted by sensors. On the other hand, eddy current separators exploit the electrical conductivity of non-magnetic metals. This is achieved by passing a magnetic current through the feed stream and using repulsive forces interacting between the magnetic field and the eddy currents in the metals (Javaid and Essadiqi, 2003). The simplest application of the process is the inclined ramp separator. The process uses a series of magnets on a sloped plate covered with a non-magnetic sliding surface such as stainless steel. When a feed of mixed materials is fed down the ramp, non-metallic items slide straight down, while metals are deflected sideways by the interaction of the magnetic field with the induced eddy current. The two streams are then collected separately.
Management of Solid and Hazardous Waste as per Indian Legislation
Published in Ashok K. Rathoure, Zero Waste, 2019
Ashok K. Rathoure, Unnati Patel
Contaminated plastic such laminated or painted plastic are removed by grinding, cryogenic method, abrasion/abrasive technique, solvent stripping method and high temperature aqueous based paint removal method. Magnetic separators are used for ferrous metals separation, while eddy current separators are used for nonferrous metals separation. Air separation system is used to separate light fractions such as paper, labels and films.
Calorific value prediction models of processed refuse derived fuel 3 using ultimate analysis
Published in Biofuels, 2023
Junaid Tahir, Rafiq Ahmad, Zighang Tian
Such MSW composition first passes through a mechanical sorting line comprising of trommel screens to separate bulky waste, non-combustible material, and hazardous waste. The described waste composition is pre-mixed in defined proportions to achieve a homogenous blend and it provides flexibility in keeping the final fluff specification meet client requirements. Afterwards, further mechanical processing includes a shredder, a separator of metals, and a drum screener. The output from a drum screener passes through a wind sifter where heavies fall, and fines pass through the eddy current separator to get rid of electromagnetic materials. Then the processed material is re-shredded to a fraction size in the range of (2–5 cm). The material type retrieved after the final stage is called RDF-3.