A Method for Leaching or
Dissolving Gold
from Ores or Precious Metal Scrap
Nicolas Geoffroy and François Cardarelli
Abstract.
- The hydrometallurgical
leaching of native gold from gold-bearing ores or the dissolution of
gold metal during the recycling of electronic and precious metal scrap
is performed every day using hazardous chemicals such as sodium cyanide
or aqua regia. These chemicals represent health and safety risks for
workers and a serious threat for the environment. However, even if
several other reagents are known to dissolve gold at the laboratory
scale, none of these are used industrially. Hot mixtures of
hydrochloric acid with strong oxidizing compounds are known to generate
in-situ nascent chlorine which is capable of dissolving gold
efficiently. In this study, the authors investigated the capability of
a hot mixture of hydrochloric acid and ground manganese (IV) oxide to
dissolve gold metal either under atmospheric or pressurized conditions.
The best result was obtained under a pressure of 639 kPa at
90°C
with a dissolution rate of 0.250 g·cm–2h–1
and it was compared
to that reported in the literature for other industrial reagents.
Journal
of Materials
Volume
57, Number 8, August
2005, Pages 47-50 [Full
text PDF file (280 KB)]
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Keywords: maths,
physics,
mechanics, quantum
mechanics,
relativity, electricity,
electrostatic, electromagnetism,
magnetism, thermodynamics, acoustics,
optics,
chemistry,
general chemistry, inorganic chemistry, organic chemistry, analytical
chemistry, semi-micro qualitative analysis, quantitative analysis,
physical chemistry,
radiochemistry, nuclear chemistry, electrochemistry, spectrochemistry,
surface chemistry,
industrial chemistry,
chemical
engineering, electrochemical
engineering,
mechanical
engineering, electrical engineering, thermal engineering, civil
engineering, nuclear engineering,
materials engineering, materials science, materials data, properties of
materials
properties, aqueous electrolytes, electrolysis, electrodics, electrode
kinetics, corrosion science, electrodeposition, electrowinning,
electrorefining, electrocatalysis,
electrodes,
inert anode, dimensionally stable anodes (DSA®), chlorine
evolution, ruthenium
dioxide (RuO2),
DSA-Cl2,
DSA-RuO2,
oxygen evolution, iridium dioxide (IrO2),
DSA-O2,
DSA-IrO2,
mixed metal oxides (MMO), activated
titanium anodes, oxide coated titanium
anodes, lead anodes,
lead-silver anodes, lead dioxide (PbO2),
spinel electrodes,
ferrites, cobaltites, lithium
metal, lithium batteries, lithium ion batteries, lithium polymer
batteries, fuel cells, molten
salts electrolytes, molten slags, liquid metals, titanium metal,
titania, titania slag, titanium slag,
titanium dioxide (TiO2),
titanates, corrosion resistance, ferrous metals (Fe, Co, Ni, Mn), pig
iron and steel, cobalt and cobalt alloys, nickel and nickel alloys,
manganese, ferroalloys, ferrosilicon, ferrophosphorus, ferrochromium,
silico-ferromanganese, ferrovanadium, ferromolybdenum, ferrotungsten,
ferrotitanium, common nonferrous metals (Al, Cu, Zn, Pb, Sn), aluminium
and aluminum alloys, aluminum and aluminum alloys, copper and copper
alloys, zinc and zinc alloys, lead, tin,
light metals, less common metals, alkali-metals, alkaline-earth metals,
refractory metals (Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Re), titanium and
titanium alloys, zirconium and zirconium alloys, hafnium and hafnium
alloys,
vanadium and
vanadium alloys,
niobium and niobium alloys, columbium and columbium alloys, tantalum
and tantalum alloys, chromium,
molybdenum and molybdenum alloys, tungsten and tungsten alloys,
wolfram, rhenium and rhenium alloys, reactive metals, noble and
precious metals (Ag, Au), silver, gold, platinum group metals (PGMs,
Ru, Rh, Pd, Os, Ir, Pt), ruthenium, rhodium, palladium, osmium,
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La), lanthanides, actinides, uranides (Th, Pa, U, Np, Pu) and
curides, uranium, thorium, plutonium, heavy metals (Zn, Cd, Hg, In, Tl,
Pb, Bi), mercury, cadmium, nonmetals, semimetals, metalloids (Si, Ge,
As, Sb, Se, Te), silicon, germanium, arsenic, antimony, selenium, tellurium,
semiconductors, superconductors,
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and soft
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