A. Serpe, P. Deplano, M. L. Mercuri, E. F Trogu

Transcription

1 University of Cagliari University of Cagliari Spin-Off A. Serpe, P. Deplano, M. L. Mercuri, E. F Trogu

2 Production concentration of critical raw mineral materials From Critical raw materials for the EU, Report of the Ad-hoc Working Group on defining critical raw materials, 30 July 2010

3 The Problem Wide usein Hi-Tech application Critical minerals Volatility of price Corrent recovering methodsare riskyand polluting Requirement of effective and safer recycling methods

4 European Directives on Waste Managment Scope: preserving the environment and the natural sources. EU waste management approach: avoiding waste by improving product design; increasing the recycling and reuse of waste. Principle: the polluter should pay European Directives: 91/156/EC on waste management Italy: Decreto Ronchi, D. L. 97/ /53/EC on end-of-life vehicles 2002/96/CE on Waste of Electric and Electronic Equipments (WEEE) Italy: D.L.July 22, 2005

5 The Solution Vision: Hi-Tech scraps will be secondary source of PM. Mission: chemistry can make innovation in the effective and sustainable PM recycling from scraps. Traditional gold mine: 2-4 g/ton of Au, in Italy WEEE: 16g/Ton of Au Electronic Waste: a gold mine!

6 PM Recovery Currently PM are scarcely recovered and the recovering is performed only in few countries such as United States, Japan and Germany. 20/10/11 Pt 35 /g Pd 14 /g Gold 38 /g Data from Johnson Mattheyand and World Gold Council

7 Methods for PM recovery Two alternative approachs: 1. Energy-intensive thermal treatments(pyrolisis in arch furnace) 2. Traditional chemical methods Further methodologies: 3. Combined thermal-chemical treatments as Pyrometallurgical Clorination: high-temperature treatment (T>400 C) by fluxing pure gasormixtureofcl 2 /CO/COCl 2 /CCl 4 /S 2 Cl 2 /SOCl 2

8 Chemical methods for PM dissolution Common lixiviantsforpm PM: Strong and Oxidising Acids(i.e.boilingaquaregia) Au,Pd,Pt Cianides in alkaline media Au-mine extraction processes and recovering plants. Thiosulfate or Thiourea proposed for Au-mine extraction processes. These methods exploit the presence of a complexing agent(cl -,CN - or S-donor), which lowers PM high oxidation potential and makes them easier tobe oxidised. Unactractive reagents forthe environmentand operators.

9 Proposed chemical approach Selected donors: exa-and and epta-atomic atomic cyclic dithioxamides. R S N n=2,3 S N (C H 2 ) n n=2, R=Me, Et, i-pr, n=3, R=Me, Et R Sulphur chelating donors whichcan can favourthe square-planar geometry preferred byd 8 -Au( Au(III), Pd(II II), Pt(II) - oxidated metals.

10 Synthesis ofthe Reagents R N n(h 2 C) N R IBr S S I 2 1:2 CHCl 3 r.t. n=3: Me 2 dazdt 2I 2 n=3: Me 2 dazdt 2IBr Non-cytotoxicand safe reagents n=2: [(i-pr) 2 pipdth]i 3

11 [Me 2 dazdt 2I 2 ]: ReactionwithPM powder Molar ratio2:1; THF o CH 3 CN o (CH 3 ) 2 O; r.t. Unidentified product * Ag CH 3 Au Pt No reaction N S I I ** Pd N S I I Ni CH 3 Cu [Cu(Me 2 dazdt) ]I 2 3 A. Serpe et al, Coord. Chem. Rev., 2008, 252, 1200.*F. Bigoli et al, Chem. Commun.,1998, 2351;**A. Serpe et al, Chem. Commun., 2005, 1040.

12 [Me 2 pipdth]i 3 : ReactionwithPM powder Molar ratio 2:1; THF or CH 3 CN or (CH 3 ) 2 O; r.t. Cu CH 3 + Pd Pt * Au N S H I 3 - N S CH 3 Ni [Ni(Me 2 pipdt) 2 ]I 6 Ag RefluxingCH 3 CN + other products A.Serpeetal,Coord.Chem.Rev.,2008,252,1200.*F.Bigolietal,J.Am.Chem.Soc.,2001,123,1788;**A.Serpeetal,Cryst.Growth&Des.,2011,11,1278.

13 Applicationfields PM recovery from: A) spent Three Way Catalysts (TWC) B) Waste from Electricand Electronic Equipments(WEEE) Our goals Replacement of more polluting and/or dangerous methods Recovery and/or recycling of high value metals

14 Three Way Catalysts Gas phase diffusion Pd, Pt Rh NO CO Dissociative adsorption Surface diffusion Surface CO 2 reaction Molecular Adsorbed adsorption product Metal Support

15 Palladium Recovery Process from TWC Quantitative yield! yield! Non-cytotoxic Nonreagents!! reagents

16 Palladium Recovery Process from TWC Pd-recovery Catalysts from Pd-complex 1200 H 2 evolution rate / µmoli h H 2 from MeOH photo-reforming da Pd(NO3)2 da (Pd(Me2dazdt)2)(I3) irradiation time / h addotto Pd T [C] TG/% DTA/uV H 2 evolution rate / µmoli h irradiation time / h da Pd(NO3)2 da (Pd(Me2dazdt)2)(I3)2 H 2 from Glicerin photo-reforming In collaboration with Prof. Paolo Fornasiero, Dip. Scienze Chimiche, UniTS.

17 Gold & Copper Recovery Process from WEEE Yield >95% Yield >95% Mg Zn HCl (1:5) + OH- NH3 H2O2

18 Gold & Copper Recovery Process from WEEE Copper reduction by metallic Zn Zn:: ~500nm 500nm particles 85 85% % Cu, 15 15% % Zn Gold reduction by metallic Mg: Mg: 0,5-10 μm particles 95 95% % Au, 5% Mg

19 CONCLUSIONS Synthesis and characterization of the two low pollutingand easy handling classes of reagents [R 2 dazdt 2IX](X=I o Br) and [R 2 pipdth]i 3 capable to dissolve NMs selectively and in mild conditions. Reactivity towards NMspowder: [R 2 dazdt 2IX] are active towards Au, Pd, while are inactive towards Pt; [R 2 pipdth]i 3 are also active towards Pt. APPLICATIONS Quantitative Pd recovery from model aged TWC. Experiments on real catalysts and on Pt recovery arein progress. Quantitative Au and Cu recovery from WEEE. A new improved method has been set-up.

20 ACKNOLEDGEMENTS AND COLLABORATIONS Dip. Chimica Inorganica e Analitica University of Cagliari Prof. Paola Deplano Dip. Scienze Chimiche e Centro di Eccellenza per i Materiali Nanostrutturati University of Trieste Prof. Mauro Graziani Dr. Paolo Fornasiero Prof. M. Laura Mercuri Dip. Ingegneria Elettrica ed Elettronica Prof. Emanuele F. Trogu Dr. Luca Pilia Dr. Flavia Artizzu Dr. Davide Espa Dr. Elisa Sessini University of Cagliari Prof. Massimo Vanzi Dip. Chimica Generale e Inorganica, Chimica Fisica, Chimica Analitica University of Parma Dr. Luciano Marchiò

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