Physical and chemical treatment of end of life panels: An integrated automatic approach viable for different photovoltaic technologies.

Different kinds of panels (Si-based panels and CdTe panels) were treated according to a common process route made up of two main steps: a physical treatment (triple crushing and thermal treatment) and a chemical treatment. After triple crushing three fractions were obtained: an intermediate fraction (0.4-1mm) of directly recoverable glass (17%w/w); a coarse fraction (>1mm) requiring further thermal treatment in order to separate EVA-glued layers in glass fragments; a fine fraction (<0.4mm) requiring chemical treatment to dissolve metals and obtain another recoverable glass fraction. Coarse fractions (62%w/w) were treated thermally giving another recoverable glass fraction (52%w/w). Fine fractions can be further sieved into two sub-fractions: <0.08mm (3%w/w) and 0.08-0.4mm (22%w/w). Chemical characterization showed that 0.08-0.4mm fractions mainly contained Fe, Al and Zn, while precious and dangerous metals (Ag, Ti, Te, Cu and Cd) are mainly present in fractions <0.08mm. Acid leaching of 0.08-0.4mm fractions allowed to obtain a third recoverable glass fraction (22%w/w). The process route allowed to treat by the same scheme of operation both Si based panels and Cd-Te panels with an overall recycling rate of 91%.

Submerged-arc welding slags: characterization and leaching strategies for the removal of aluminum and titanium.

In the present study, submerged-arc welding slags were characterized by applying a variety of methods, including X-ray fluorescence, X-ray diffraction, particle size, Raman spectroscopy, and scanning electron microscope with energy dispersive X-ray analysis. The content of Al proved to be quite similar within neutral and acid slags (10-14%), while that of Ti proved to be much higher in acid slags (approximately 10%) than in neutral slags (<1%). The presence of spinel structures associated with Al species could also be identified in the analyzed samples. This characterization study was accompanied by leaching tests performed under changing operating conditions in an attempt to evaluate to what extent the Al and Ti bearing components could be removed from the slags. The leaching work involved three distinct strategies: (i) NaOH leaching followed by H(2)SO(4) leaching, (ii) acid leaching (HCl and H(2)SO(4)) using oxidizing/reducing agents, and (iii) slag calcination followed by H(2)SO(4) leaching. In the best result, 80% of Al was extracted in one single leaching stage after calcination of the acid slag with NaCl+C at 900 °C. By contrast, the removal of Ti proved to be unsatisfactory.

Acidic leaching both of zinc and iron from basic oxygen furnace sludge.

During the steel production in the basic oxygen furnace (BOF), approximately 7-15 kg of dust per tonne of produced steel is generated. This dust contains approximately 1.4-3.2% Zn and 54-70% Fe. Regarding the zinc content, the BOF dust is considered to be highly problematic, and therefore new technological processes for recycling dusts and sludge from metallurgical production are still searched for. In this study the hydrometallurgical processing of BOF sludge in the sulphuric acid solutions under atmospheric pressure and temperatures up to 100 °C is investigated on laboratory scale. The influence of sulphuric acid concentration, temperature, time and liquid to solid ratio (L:S) on the leaching process was studied. The main aim of this study was to determine optimal conditions when the maximum amount of zinc passes into the solution whilst iron remains in a solid residue.

Hydrometallurgical processing of carbon steel EAF dust.

In this study, the hydrometallurgical processing of electric arc furnace (EAF) steelmaking dust is investigated on a laboratory scale under normal temperature and pressure conditions. The behaviour of zinc and iron under the influence of sulphuric acid as the leaching agent is discussed. The dependence between the temperature and acid concentration is investigated. The main aim is the transfer of zinc into the solution while iron ought to remain as a solid residue. The hydrometallurgical recovery of zinc from EAF dust is feasible with relatively high recovery yield, while iron mostly remains in the solid phase. It results from the use of sulphuric acid in low concentration. This way, it is possible to set up the conditions for the EAF dust leaching, adjusting sulphuric acid concentration in order to achieve an optimum zinc yield to the solution without iron dissolution. However, the problem is that the chemical and mineralogical composition of each steelmaking dust is individual.