ESCUELA POLITÉCNICA NACIONAL Quito - Ecuador Faculty of Chemical Engineering and Agroindustry Department of Extractive Metallurgy

Pb Co Ni Cd Cr

Au, Ag, Pd, Nb, Rh Epoxy Resins Glass fiber Cu, Pb, Co, Ni, Fe, Cd, Cr Flame Retardant PVC/PC/ABS ceramics

Low cost and effectiveness to dissolve noble metals. 4Au + 8(CN) - → 4Au(CN) 2 - Au > Ag > Pd > Rh [CN] -, d p, t Cyanicide (Cu) Cyanidation

The elements from the group of Platinum (Pd, Rh) are soluble in mineral acids Pd + 2HNO 3 → Pd(NO 3 ) 2 + 2H - Pd + H 2 SO 4 → Pd(SO 4 ) + 2H - With HNO 3 and H 2 SO 4 the dissolution is slow. Nd y Rh are dissolved with difficulty Presence of Cl - ion benefits the dissolution ofPd Acid Leaching

1000 ºC 1h 0,5 g 30 ml Aqua Regia T a – 850ºC 3 h 0,72 atm 21% O ºC 1h Samples Characterization

Electronic Microscope MEB-EDX

MetalConcentrationAverage Au g/t421 g/t Ag g/t1355 g/t Pd g/t74 g/t Rh g/t49 g/t Nb5 – 40 g/t15 g/t Cu %29% Chemical Characterization

muestra 72 Fecha:7/27/2010 6:21:10 PM Tamaño de imagen:384 x 384 Aum:500x HV:20.0kV

Cyanidation Preliminary Treatments Parameter Definition ([NaCN], t)Parameter Definition ([NaCN], t) Size reduction Size reduction Roasting Leaching NH 3 / HNO 3 Leaching NH 3 / HNO 3 Acid Leaching Preliminary Treatments Parameter Definition (Concentration, t)Parameter Definition (Concentration, t) Size reduction Size reduction Roasting

[NaCN]2 g/L Time24 h pH10,5 % Solids2,5-5% Stirring500 rpm 4x4 cm 1x1 cm 7x7 mm 5x5 mm 1000  m 136  m Size reduction, roasting and cyanidation

Influence of roasting and size reduction in the gold and silver cyanidation [NaCN] 2 g/L; solids 2,5-5%, time24 hours

Influence of the concentration of cyanide in gold and silver recovery Roasted sample; d  m; solids 2,5-5%, time 24 hours

Influence of cyanidation time in the gold and silver recovery Roasted sample; d  m; solids 2,5-5%, [NaCN] 4 g/L

NH 3 (v/v)HNO 3 (v/v) 9,7 %19,5 % 16,7 %33,3 % 14 % Solids 2 h 500 rpm Preliminary treantments: Leaching NH 3 / HNO 3

Influence of pretreatments with NH 3 and HNO 3 Roasted sample d  m; Pretreatment time 2h

Concentration HNO 3 35 g/L Concentration H 2 SO 4 35 g/L Time1 a 6 h % Solids2,5 - 5 Stirring speed.500 rpm Acid Leaching Concentration NaCl 0,1 M Concentration H 2 SO 4 60% w/w Time1 a 6 h % Solids8 Stirring speed500 rpm

Kinetics of paladium leaching Roasted sample; d  m; solids 2,5-5%, [acid] 50 g/L

Effects of chloride ions in the leaching of paladium with sulfuric acid Roasted sample; d  m

Leaching HNO 3 Filtering Electrowinning Elution Scrubber Dismantling Roasting Milling Leachinf NH 3 Filtering Cyanidation CIP Filering Discarded Cellphones Printed circuit board Solid Waste Gases to atmosphere Ammonia liquor Cyanide liquor Cases, keyboards, Screens Charged Carbon Au, Ag Ag, Pd Acid liquor Gases

It is factible to recover 85% Au, 80% Ag, 80% Pd y 80% Cu by installing a treatment plant of 195 kg/month for the printed circuit boards of discarted cellphones Nb y Rh couldn`t be recovered Conclusions

Economic criteria Capacity195 kg/month InvestmentUSD VANUSD TIR18% Investment recovery 5 years C/B1.5

ESCUELA POLITÉCNICA NACIONAL Quito - Ecuador Faculty of Chemical Engineering and Agroindustry Department of Extractive Metallurgy