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Hydrometallurgical treatment of electronic scrap to recover gold and silver.

Authors
Hilliard-HE; Dunning-BW Jr.; Kramer-DA; Soboroff-DM
Source
USBM 1985 Jan; :1-20
Link
NIOSHTIC No.
10004439
Abstract
The Bureau of Mines investigated hydrometallurgical procedures for concentrating precious metals from a mechanically processed metal fraction of obsolete military electronic scrap. Feed material for the leaching procedures described in this report was the high-tension-separated metal concentrate obtained as a fraction from mechanically processing partially stripped electronic units. Initial pretreatment with a 20-wt-pct-NaOH solution solubilized most of the aluminum. After washing, the resulting residue was incinerated to destroy any organics attached to metal particles. The incinerated residue was leached with 20-vol-pct H2SO4 solution using two methods, countercurrent pressure and ultrasonic-aided leaching, to solubilize the base metals, predominantly copper. Silver was recovered from the base metal leach residue using 50-vol- pct HNO3, and gold contaminated with several percent palladium was recovered from the silver leach residue using aqua regia. The impure silver and gold plus palladium products represent about 1.5 Wt pct of the high-tension-separated metal concentrate. Included is a three-step process evaluation study of mechanical processing of general electronic scrap and two hydrometallurgical procedures for leaching high-tension-separated metallic concentrates obtained from the mechanical processing step. Process evaluation concluded that only mechanical processing is economically viable.
Keywords
Waste-treatment; Electronic-equipment; Electronic-components; Electronic-circuits; Metal-compounds; Metallurgical-processes; Metallurgy
Publication Date
19850101
Document Type
IH; Report of Investigations
Fiscal Year
1985
NTIS Accession No.
PB83-214429
NTIS Price
A03
Identifying No.
RI-8940
NIOSH Division
AVRC
Source Name
U.S. Bureau of Mines
State
MD
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