8/13/2019 Total Pressure Oxidation
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Total pressure oxidation
La oxidacin a presin total de concentrados de cobre es una opcin
potencialmente viable para el
tratamiento de concentrados de cobre que se encuentran ya sea de
baja ley o que contengan
impurezas significativas. Ambos tipos de concentrado estn
fuertemente penalizados en los
contratos de fundicin. El proceso de oxidacin a presin total
consiste en aplicar un sistema
autoclave al concentrado de cobre a una temperatura de 200-220 C
bajo cierta presin deoxgeno(3040). La descarga autoclave se puede
separar en un slido (residuo de la oxidacin ) y
un lquido ( solucin de oxidacin ) del producto . La solucin de
oxidacin puede ser tratada para
la recuperacin de cobre mediante SX - EW o directamente por EW.
La recuperacin directa de
cobre por EW requiere la eliminacin previa de selenio y telurio
en la cementacin de chatarra de
cobre. El residuo de la oxidacin se lava a fondo para eliminar
el cido y el cobre disuelto antes de
la recuperacin de metales preciosos por cianuracin convencional
en presencia de cal. Las
recuperaciones de cobre en oxidacin por autoclave y la
recuperacin de oro por cianuracin del
residuo oxidacin superaron el 99%. Opera en la planta Bagdad, en
Arizona (empresa Phelps
Dodge)
Chalcopyrite Oxidation/Iron Hydrolysis:
CuFeS2 + 4.25O2 + H2O = CuSO4 + 0.5Fe2O3 + H2SO4Pyrite
Oxidation:FeS2 + 3.75O2 + 2H2O = 0.5Fe2O3 + 2H2SO4
The total pressure oxidation process uses high temperature and
pressure oxidation conditions to oxidize all
sulfide minerals to sulfates and sulfuric acid. Conveniently,
total pressure oxidation also results in iron
precipitation as hematite. Total pressure oxidation plants
operated in the US in the 1950s for recovery of
copper, cobalt and nickel from complex ores, so this technology
is not regarded asnew. Phelps Dodge has
now revitalized the large-scale application of total pressure
oxidation at the Bagdad plant in Arizona. At this
facility approximately 16,000 tpa of Cu can be recovered from
concentrates that previously were sent to a
smelter facility. Under total oxidation conditions, 140 short
tons of acid are produced per day for application
to the stockpile leach operation at Bagdad. In this way, an acid
credit is derived. A single autoclave is used to
leach the concentrates which then proceed to flashing (to return
the slurry to atmospheric pressure), slurry
cooling, CCD washing and then copper SX/EW. The autoclave stream
is merged with the stockpile leachsolution stream to provide a
combined PLS feed to the SX/ EW facility. The acid from the
autoclave process
is then recycled in the SX raffinate back to the stockpile
leach. The washed autoclave residue is neutralized
with lime in 4 stages. If precious metals were present (very low
precious metals in the Bagdad concentrate),
the neutralized residue could be cyanide leached. The total
pressure oxidation process is very suitable for
application where the acid from pressure leaching can be used
beneficially. The process has been
commercially demonstrated at a large-scale and could easily be
scaled up to larger size if required. Total
pressure oxidation for copper concentrate treatment should now
be regarded as proven technology.
La oxidacin a presin total es muy manejable para la aplicaciones
donde el cido proveniente de
la lixiviacin a presin puede ser usado beneficiosamente. El
proceso ha sido comercialmente
demostrado a gran escala y podra fcilmente escalar en gran
medida si es requerido. La oxidacina presin total para el
tratamiento de concentrados de cobre puede ahora ser calificado
como
tecnologa probada.
