Title: Council for Mineral Technology
1Council for Mineral Technology
Developments in the hydrometallurgical processing
of base metals and uranium 24 February 2009 Dr.
Roger Paul General Manager Technology
2Introduction
- Crude forms of hydrometallurgy were practised
hundreds of years ago - Lower grade and more complex ores, e.g. Ni
laterites - Metal recoveries are of increasing importance to
be cost effective - Metal purities more stringent for modern
applications - Technological advances, e.g. pressure leaching
- Major developments in materials of construction
- Environmental and energy issues around smelting
technologies
3Outline
- Cu recovery from sulphides, low grade ores
- Ni recovery from sulphides and laterites
- Co recent developments in Africa
- Uranium higher price initiated numerous projects
- Conclusions
4Escondida Sulphide Leach Chile
- Bioleaching (mesophiles)
- Low-grade, run-of-mine (ROM) ore with SX / EW
- Designed to produce 180 000 tpa copper cathode
- Project cost US 870m (includes desalination
plant at Coloso) - Production at plant began in 2007
5Mintek NICICOs Sarcheshmeh Mine, Iran
- Bioleaching (mesophiles / thermophiles)
- Pilot heaps (6 m height, 20 000 t)
- Ore 100 passing 25 mm, transitional (53 of
Cu(T) as CuFeS2) - Maximum temperatures up to 55C
- Cu dissolution 60 (200 - 300 days)
6Other
- Pacific Ores BioHeapTM process
- Completed a 4 500 t pilot heap facility, inner
Mongolia - Microbial assisted leaching of low-grade, copper
mineral sulphide (whole) ores - Geobioticss GEOLEACHTM process
- Low-grade, copper mineral sulphide (whole) ore
- Mesophiles, moderate and extreme thermophiles
- Planning demonstration heap at Quebrada Blanca
Mine, Chile
7Outotecs HydroCopper
HydroCopper Process Block Diagram
8Outotecs HydroCopper
- Atmospheric Leaching
- Concentrate (CuFeS2) leaching in acidic, chloride
medium use of chlorine / oxygen - Chloride stabilizes Cu(I) which is precipitated
as CuO before melting - Produce high-quality copper powder (LME A Cu
cathode equivalent), which can be melted and cast
in required form - Process produces no sulphuric acid
- Can treat variety of copper concentrates (incl.
lower grades) - Reduced capital and operating costs with process
plant near concentrator (transportation / storage
needs eliminated) - Reagents regenerated (chlor-alkali electrolysis
step) - Gold and silver recovered
- Closed water circulation efficient handling of
process off-gas - Residues (leach) S0, hematite or goethite
9Outotecs HydroCopper
- Presently, engineering a commercial plant for
Mongolian Erdenet Mining Corporation (Mongolia)
to produce 50 000 tpa copper wire rod - Another plant to be build (27 000 tpa) for
Zangezur Copper Molybdenum Combine AGs mine in
Karajan, Armenia
Demonstration Plant in Pori, Finland
10GalvanoxTM
11GalvanoxTM
- Atmospheric Leaching
- Primary copper sulphide (CuFeS2) concentrates
leached in acidic, iron sulphate medium - Enhanced dissolution kinetics achieved by means
of pyrite (FeS2) as catalyst - Copper recoveries of 98 in 4 h residence time
more typically, 20 h, 80C (depending on extent
of FeS2 recycle) - S0 formation
- Compatible with SX / EW
- Used in combination with high-pressure autoclave
for acid, heat and Fe(III) generation - Enhanced enargite (Cu3AsS4) dissolution kinetics
also achieved with FeS2 as catalyst - Arsenic converted into environmentally stable
scorodite
12Sepon Process Flow Diagram
13Sepon
- Atmospheric / Pressure Leaching
- Secondary Cu-sulphide concentrates leached in
acidic, iron sulphate - Used in combination with high-pressure autoclave
for acid, heat and Fe(III) generation - Commercialized successfully Sepon Plant, Laos
- Could be modified for primary copper sulphides
(CuFeS2) - Main difference with respect to GalvanoxTM
process - GalvanoxTM CuFeS2 treated in atmospheric
leach - Equipment size, capital and operating costs
not linked to primary copper sulphide content of
feed - Sepon CuFeS2 treated in high-pressure
autoclave - Equipment size, capital and operating costs
directly linked to primary copper sulphide
content of feed - Arsenic bearing concentrates conversion into
environmentally stable scorodite
14Sepon Copper Project, Laos
15CESL Process Flowsheet
16Teck Comincos CESL Process
- Pressure Leaching
- Can treat nearly all copper concentrates (incl.
CuFeS2) (both high and low grades) - High metal recoveries of 96 to 97 to LME Grade
A Copper - Reagents recycled
- Elemental sulphur (85 to 95) and hematite
- Low Capex and Opex
- Efficient / economic recovery of precious metals
- Handles common impurities well
- Net user of water (no effluent)
- Moderate energy consumption (3200 kWh / t Cu
incl. oxygen plant) - Construction of Usina Hidrometalúrgica Carajás
(UHC) prototype plant recently completed (10 000
tpa Cu cathode). Near Carajás, Brazil where Vale
operates Sossego copper mine
17UHC Project, Brazil
18Morenci Flowsheet
19Freeport - McMorans Morenci
- Pressure Leaching
- Bagdad (Phelps Dodge) demonstration plant medium
temperature pressure leaching of copper
concentrate with direct electrowinning (DEW)
(commercial demonstration, 2005) - Morenci Western Copper concentrate mixed
chalcopyrite, covellite, chalcocite, pyrite - 215 000 tpa of concentrate (grade 34 Cu)
- 147 million pounds Cu produced per annum
- 97 Cu recovery
- Capital cost US 250m (incl. concentrator
refurbishment , concentrate leach facilities) - Commissioning / start-up 2007
- Pressure leach vessel systems, L/S, DEW, silica
removal, construction materials working well to
date
20World Nickel Resources
Bacon, 2004
21Tati Nickel Flow Diagram
- Treating lower grade Ni-sulphide concentrate
22Tati Nickel Approaches
- Ultra-fine milling lower temp leach
- S reports to leach residue
- Ni SX using versatic Mintek synergist
- The V10/Nicksyn system was more robust, and the
circuit operation was simpler risk associated
with gypsum minimised - Higher recoveries of gt99.8 were achieved with
minimal or no calcium co-extraction. - The V10/Nicksyn system was operated with one
less extraction stage, yielding higher
recoveries. Potentially, two less extraction
stages could be used. - Ammonia for neutralisation
- Lime boil employing vibrating mill to limit
impact of gypsum scaling
23Laterite Minerals
- Limonite, asbolite (1-1.7 Ni, 0.1-0.2 Co)
suitable for PAL and Caron process - Nontronite (1-5 Ni, 0.05 Co) suitable for
PAL and smelting - Serpentine (1.5-10 Ni, 0.05-1 Co) typical
1-2 Ni suitable for pyromet processes
(ferronickel and matte smelting) - Garnierite (10-20 Ni, 0.05-1 Co) typical 2-3
Ni suitable for pyromet processes (ferronickel
and matte smelting, especially high C ferronickel)
Bacon, 2004
24Laterite Simple Process Routes
Malachite Consulting
25Laterite Simple Process Routes
Bacon, 2004
26Laterite Cost Comparison (Rusina)
Cost Comparison as presented by Rusina
27Goro Process Selection
- Pyromet route drying (ore 50 mositure)
selective reduction/smelting high CAPEX and
energy poorer Ni and Co recoveries - Relatively low saprolitelimonite ratio and
relatively low Mg-content of saprolite hydromet
HPAL route selected - HPAL lower CAPEX and OPEX (energy consumption
lower no drying required) - Higher Ni and Co recoveries
- Ni and Co products sulphide ppt considered
direct SX more cost-effective - Fe3 and Cu2 to be removed efficiently prior to
SX cause oxidation of reagent (regeneration of
reagent part of flowsheet)
Bacon, 2004
28Goro Process Flowsheet
29CYANEX 301
Extraction curves for 15 vol. Cyanex 301
- No Ca, Mg and Mn extraction
- No neutralisation required for Ni, Co extraction
- Sensitive to Cu and Fe in PLS
- Stripping with HCl
30Goro innovative approaches
- Cu removal by IX to ensure very low level
- Cyanex 301 no extraction of Mn, Mg, Ca
- No neutralisation required for Ni, Co extraction
(for limited concentration of Ni) - Regeneration of oxidised Cyanex 301 on site
(oxidation limited with use of BPCs) - Switching of sulphate to chloride medium
- IX for Zn removal to low levels
- Should currently be commissioning
31Ravensthorpe Atmospheric and HPAL
Shipped to Yabulu for refining
32Laterites Heap Leach Developments
- Existing operations Murrin Murrin (Minara
Resources) - Committed projects Caldag (European Nickel)
- Projects in development
- Vale Inco
- Metallica (Queensland)
- GME Resources (WA)
- Rusina (Phillipines)
- Nickelore (WA)
- RMS (PNG)
- Concerns stability of heap and associated
percolation efficiency
33Costs Various Process Options
- Why considering heap leaching when it is expected
that it might be a challenge?
34Caldag European Nickel
- Heap leaching Caldag laterite contains low clay
content - 3 leach phases neutralisation (Mg leaching) (35
kg/t H2SO4), primary (116 kg/t H2SO4) and
secondary leaching (377 kg/t H2SO4) - Primary leach intermediate product 33 Ni, 1.5
Co - Secondary leach intermediate product 25 Ni, lt1
Co, 7 Mn
35Caldag European Nickel
36Co production Projects in DRC, Zambia
- Co market increased from 35 to 60 ktpa due to
demand - Price increased from US20 to US50
- Mintek evaluated many different flowsheets for
numerous clients - Various products targetted metal, hydroxides
(low and high grade), carbonates, oxide - Process options
- Classical precipitation using lime/limestone,
MgO, Na2CO3 - Solvent extraction
- Price sensitive to the type of product and the
Coimpurity levels - Transport costs of reagents and products high
products aimed at as high as possible Co content
37Oxidative Precipitation using Air/SO2
- Oxidative precipitation of Fe and Mn using
air/SO2 received much attention from various
institutes - Very attractive process option, as SO2 generally
available on site from either roaster or S-burner - Fe can be oxidised quantitatively at relatively
low pH values (2-2.8) within a reasonably short
period (2 g/L within 1 hour) - Mn oxidation done at somewhat higher pH values
(3-3.5) - Co losses to be minimised
- No commercial plant yet, Ruashi being
commissioned - Test work indicated that gas mixing, sparging and
agitation critical - Energy demand for agitation to be optimised
38Solvent Extraction
- Purification of Co stream DEHPA for Zn, Mn, Ca
- Ca extraction will result in gypsum precipitation
in strip circuit when using H2SO4 as strip
liquor, unless flowrate similar to PLS flowrate
so that gypsum maintained below solubility level - Strong extraction of Fe3 ? requires stripping
with HCl - Co SX using Cyanex 272 for Zn removal, and for Co
recovery and separation from Ni - More than one type of SX reagent in one circuit a
major concern this can be designed to prevent
contamination, but there is a risk - Neutralisation required during purification and
recovery of Co - Contamination of effluent streams with dilute
Na2SO4 is an environmental issue - Future of SX for Co
- need to be able to produce a concentrated stream
that will make crystallization viable, or - neutralization by means of ammonia that could be
recycled (lime boil an problematic operation)
39Classical Precipitation
- Precipitation with lime/limestone
- Readily available, relatively cheap
- Low grade Co (15-17 Co in dried solids)
- Mass/volume of cake cause complications when in
loop with EW - Transport costs/ton Co very high
- Precipitation with Na2CO3
- Environmental issue produce dilute Na2SO4
- Produce 40-50 Co product
- Can be calcined for further upgrading of product
- Precipitation with MgO
- Produced high grade Co product (40)
- Mg can be precipitated from barren stream prior
to dumping - Very expensive reagent
- Efficient use requires careful design
considerations - Impact on EW bleed can be large if reagent
addition un-optimal
40Ion Exchange Co purification
- Purification of Co stream Zn, Cu, Ni, and more
recently Cd - Zn and Cu can be removed from the Co PLS stream,
or advance electrolytes to the required levels
(30 mg/kg in Grade A metal) - Ni removal Dowex M4195 resin most effective
option, but very costly - Cd removal by IBCs Molecular Recognition product
(10 mg/kg in Grade A metal) - Ionex or Septor CCIX systems considered where
resin cost high - Ion exchange systems efficient to consistently
achieve the required levels
41Uranium
- Revival after decades of inactivity!
- Previous technologies still valid for today
- Some new developments could make projects
economically more viable, eg. direct SX using
BPCs and RIP
42Bateman Pulsed Columns (BPC)
Mixer/Settlers BPC
Extraction Staged Continuous
Efficiency Lower for cost-effective of stages High
Entrainment Poorer Improved
Moving parts High Low
Maintenance High Low
Footprint Large Small
Solvent vapour loss Higher Lower
Safety Higher fire hazard Much lower
43BPC vs MS Stage Performance
Improved efficiency with marginal increase of
capital cost
Operating Line O A lt1
NTU 2
NTU 4
Org g/l
Operating line O A 1
Aqueous g/l
Raff Concentration
Bateman
44Olympic Dam recovery of Uranium by BPcs
45Uranium One BPCs Klerksdorp
46RIP - Metrix
- Mintek developed RIP for Au, base metals and
uranium - Currently testing 3 resins for their
metallurgical performance in laboratory as well
as durability in 2m3 Metrix plant - Suitable for recovery and upgrading of uranium
from pulps, especially where solid/liquid
separation costly - Kayelekera, Paladin Resources, Malawi currently
commissioning RIP application
47Metrix Demonstration Plant
48Hydromet Challenges
- Cu chalcopyrite, especially ambient conditions,
remains difficult especially for low grade ores - Ni laterites a number of laterite projects to
date have failed or performed poorly, so it
remains a challenge to get it right - Water availability and quality (now desalination
plants part of CAPEX/OPEX of new plants) - S and acid balance in world often not used where
produced, transport costs high storage
facilities limited - All S used as H2SO4 needs to be neutralized and
dumped
49Thank you
www.mintek.co.za