1 Fundamental Experiments for the Development of an Aero-suspension Dense Media Separator for Aluminium-Copper Scrap Recycling József FAITLI 1 , Sándor NAGY 2 , Ádám RÁCZ 3 , Márton VITÁNYI 4 1,2,3 Associate Professor, 4 CEO, University of Miskolc, Institute of Raw Materials Preparation and Environmental Processing 123 Inter-metal Kft., Hungary, Budapest 4 Hungary, 3515 Miskolc - Egyetemváros, ejtfaitj@uni-miskolc.hu ABSTRACT The EU’s circular economy concept necessitates the recycling of one or more times used material streams into the production – consumption cycle again and again. The commonly known problem of limited numbers of recycling cycles of plastics drives economy into metals usage again, because for these materials the number of recycling cycles is not limited. Therefore, the efficient and economic separation of mixed aluminium and copper scraps is an important issue for our society. There are existing wet (dense media separation, etc.) and dry (eddy current separator, but its applicability is limited for this task, air separator, etc.) technologies for the upgrading of the 30-100 mm particle size range scraps. Wet separation has to be faced to the handling of contaminated water, therefore authors has started the development work of a dry aero-suspension dense media separator. Fundamental research has been done. Laboratory scale test equipment had been made by with a given powder could be fluidised, the necessary air pressure could be set and the air flow rate could be measured. Systematic test series had been made with the lab-scale test equipment to find suitable particulate materials, to figure out their optimal particle size range, to find suitable technical parameters to establish stable fluidised bed and to find a suitable construction to distribute air below the powder charged bed. Design and construction of continuous operation pilot-scale and industrial size machines had also been done. Keywords: Fluidised bed, aero-suspension, dense media separator, aluminium and copper scrap, Bingham-plastics rheology. 1. INTRODUCTION AND LITERATURE SURVEY The fluidised bed aero-suspension dense media separator is well-known equipment (Anjaneyulu and Khakbar 1995, Basu 2006, Beeckmans and Minh 1977, Gibilaro 2001, Sahu et al. 2009). According to its operating principle there is a solid-gas fluidised bed made by blown in air from the bottom into the bulk granular working media. The mixture density of the fluidised solid-liquid dense media can be controlled by the quantity of the blown in air and then the heavier particles of the raw material will settle and lighter particles will float. Comparing to the wet dense media separation, there is no need for any liquid for the dry process, therefore no need for the clarification for the separated products and no need for a water handling system. Therefore dry dense media separators are widely applied in the industry. The first application of fluidisation was invented by Brötz in 1900. Brötz applied a counter- current water flow to loosen a sand water filtration bed. First patent of fluidisation was applied for a catalyst by Phillips and Bulteel in 1910. The catalyst was transported into a fluidised gas chamber where the reaction was more efficient in the diluted solid – gas system. The first industrial application was the Winkler gas generator developed by BASF in Germany in 1921. Brown coal was gassed in the cylindrical shape fluidised bed reactor (Leva, 1967). This process was first applied in the pharmaceutical industry by Wurster for the coating of tablets in 1960. Afterward, it had been applied widely in pharmaceutics (Dévay, 2013). Aero-suspension dense media separation is also widely used in waste management. A gas-solid fluidized bed separator was applied in laboratory scale for shredded municipal bulky solid waste separation (Sekito et al. 2006). Separation of harmful impurities from refuse derived fuels (RDF) was carried out in a solid-gas fluidized bed (Krüger et al. 2014). There are several scientific and practical challenges to be solved for the development of a separation machine. The most important might be the one of how to establish homogeneous solid-gas distribution in the fluidised bed. There are several unwanted phenomena that might occurs at insufficient bed operation such as, bubbling, slugging,