6 Copper Ores Bio Leaching
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Transcript of 6 Copper Ores Bio Leaching
Copper extraction technology
• World copper production has increased steadily in the period 1964-2007 from 9 Mt to 16 Mt per year.
• In 2008 the copper production will be close to 18 Mt.
• More than 20-25 % of that copper is produced via biohydrometallurgy
High concentrations of Cu (20-25g/L) are required if iron cementation is used, midrange concentrations (10-12 g/L) are used in solvent extraction.
Copper bioleaching plants
Region /mine Ore processed [t/day] Cu production [t/year] Cerro Colorado, Chile 1993 Chalcocite, covellite [16 103] 100 103
Quebrado Blanc, Chile 1994 Chalcocite, [17.3 103] 75 103
Zaldivar, Chile 1998 Chalcocite [20 103] 150 103 Lomas Bayas, Chile 1998 Oxides/sulfides [36 103] 60 103 Cerro Verde, Peru 1977 Oxides/sulfides [32 103] 54.2 103 Escondida, Chile 1995 Oxides/ sulfides 200 103 Morenci, Arizona 2001 Calcocite, pyrite [75 103] 380 103 S&K Copper, Monywa
Myanmar 1999 Chalcocite [18 103] 40 103
Jinchuan Copper, China 2006 Chalcocite, covellite 10 103
Copper ore bioleaching
• Copper sulfide ore bioleaching processes are currently under full development in Chile.
• Bioleaching processes are realized as:Treatment of secondary sulfide in heapsLow-grade ores in dumpsBioleaching of concentrates in reactors at
high temperature
Copper minerals for bioleaching
• Chalcopyrite CuFeS2 is the most abundant copper mineral in nature. (70% of copper reserves in the world).
• Covellite CuS
• Chalcocite CuS2
• Bornite Cu5FeS2
Chalcopyrite bioleaching
• Chalcopyrite dissolves in the presence of ferric ion (Fe3+) according to the following reaction:
CuFeS2+ 4Fe3+Cu2+ + 5Fe2+ + 2S0
CuFeS2+ 4Fe3+ + 3O2+ 2H2O Cu2+ +5Fe2+ + 2H2SO4
Silver-catalyzed chalcopyrite leaching
• In the presence of silver ions the leaching of chalcopyrite takes place according to the following reactions:
• CuFeS2 + 4Ag+ Cu2+ + Fe2+ + 2Ag2S
• Ag2S + 2Fe3+ 2 Ag+ + Fe2+ + S0
The rate of copper extraction is a faster in the presence of silver ions.
Ag2S layer is porous.
Microorganisms
• Amongst the microorganisms participating in copper bioleaching are:
Iron-oxidising bacteriaSulfur-oxidising bacteriaHeterotrophic bacteria
(Iron–oxidising bacteria are critical for keeping a high oxidising potential in solutions)
BacteriaMesophiles -30-42oC, rod-shaped bacteria with diameter of about 0.5-2.0 m
Moderate thermophiles,
45 – 55oC
similar morphology
Extreme thermophiles 60 – 90oC
Spherical shape, diameter 1-2
Heap bioleaching
• Copper is the metal recovered i the largest quantity by the heap bioleaching.
• The large copper leaching operation are those by Sociedad Contractual Minera El Abra and the Codelco Division Radimiro Tomic both in Chile producing 225 000 and 180 000 tonnes Cu per annum respectively.
• Gold ore is also preatreated by bioleaching in heaps by Newmont Mining in the Carlin Trend region, Nevada.
Heap creation
• Copper ores containing such minerals as chalcocite (Cu2S) or covellite (CuS) are crushed, acidified with sulfuric acid and agglomerated in rotating drums to bind fine material to coarser agglomerates.
• These agglomerates are stacked in the heaps onto lined pads on the aeration pipes are placed.
• The stacked heaps are irrigated with an iron-containing solution through a second system of pipes laid on the heap surface.
• In China, the first commercial plant of bio-heap leaching with a capacity of 10,000 t Cu/a at the Zijinshan Copper Mine started operation by the end of 2005.
• The ore contained the relative high proportion of pyrite (up to 5.8%)
Base metals bioleaching
• Bioleaching may be used as an alternative process for extraction and recovery of other metals like:
NickelZincCobaltMolybdenumThese metals occur in significant quantities
in sulfidic ores (polymetallic ores)
The companies have developed biooxidatio process for use in metal extraction
Newmount
mining
BIOPROTR Process – heap leaching of refractory gold ore
BHP Billiton Ltd.
BioCOPTM Process –agitated tank oxidation and bioleaching of copper sulfide
BioNICTM Process – agitated tank oxidation and leaching of nickel sulfides
BioZINCTM Process – agitated tank oxidation and leaching zinc sulfides
Godl FieldsnLtd.
BIOXTM Process – agitated tank oxidation and leaching of copper sulfides
Bac Tech Environmet
BacTech/Mintek Process – agitated tank oxidation and leaching of copper sulfides
Geo Biotics Inc.
GEOCOATTM Process – heap leaching sulfide mineral concentrates
Nickel
• The nickel mineral most commonly mined is pentlandite (Fe,Ni)9S8. Nickel sulfide –millerite NiS.
• Billiton developed a process named BioNICTM to treat low-grade nickel ores, based on the gold bioleaching.
• Nickel could be recovery from lateritic ores using heterotrophic microorganism such as Aspergillus niger and Penicillium.
Talvivaara dopsit
• The Talvivara deposit is the largest in the world nickel deposit with 340 Mt of ore with an average contents of 0.27% Ni, 0.02% Co and 0.56% Zn.
• Heap bioleaching would make Talvivaara
the most attractive source of Ni in the whole of Europe.
Sphalerite ore bioleachingThe ore contained sphalerite (ZnS) and pyrite FeS2
Variation of the ferrous (Fe2+) and ferric (Fe3+) concentration
Variation of zinc (Zn2+) ion concentration
Cobalt
• Bioleaching of cobalt-containing pyrite from KCC Kasese industrial operation.
• The amount of flotation concentrate was approximately 900 000t and contained approximately 80% pyrite and 1.38 % cobalt.
• The gangue minerals are mostly quartz, silicates and gypsum.
• The predominat organisms:Letospirillum (tow different strains), Acidithiobacillus thiooxidans, Acidithiobacillus caldus, Sulfobacillus thermosulfidooxidans.