The IsaMill A Great Australian Mining Innovation Past, Present, Future
N. W. Johnson
Principal Consultant Mineralis Consultants Pty Ltd
1 CONTENTS
1. PAST Historical setting for McArthur River deposit* – 1955 to 1980 Development Program that commenced in 1989 *IsaMill technology developed for the McArthur River deposit
2. PRESENT IsaMill – Contributions to the present metallurgical landscape
3. FUTURE IsaMill – Possible directions for the future
Relevant Companies: MIM Holdings Limited (Mount Isa Mines Limited) (McArthur River Mining Pty Ltd) Xstrata, Glencore 2 Location of McArthur River Mine (HYC Deposit) Geological location – Carpentaria Inlier (from brochure of McArthur River Mining Pty. Ltd.)
3 McArthur River stratiform Zn-Pb deposit in Carpentaria Inlier Background to the deposit 1. Discovered by geologists of Mount Isa Mines Limited in 1955.
2. Large stratiform Zn-Pb-Ag deposit by world standards: Open pit 227Mt 9.2% Zn, 4.1% Pb, 41 ppm Ag
3. Exposed only to low level metamorphism, hence minimal grain size increase.
Mean grain size No. 2 O/B (µm): PbS <3, (Zn,Fe)S 36, FeS2 43, NSG 9
4. Contains a portion of its pyrite in the “carbonaceous pyrite” form (naturally hydrophobic), a property it shares with other stratiform Zn-Pb-Ag deposits in the Carpentaria Inlier (e.g. Mt. Isa, George Fisher, Century Zinc, Dugald River)
Development thwarted up to 1980 by: 1. Lack of infrastructure in the isolated region i.e. increased capital costs 2. High capital costs for additional reasons, including O/B being underneath a major river (diversion needed if open pit) 3. Fine grained nature of the mineralisation (a metallurgical problem) 4 Background – McArthur River zinc/lead/silver deposit
• Mid 1960’s “Light on the hill” in difficulty - UQ lecturers in U/G courses
• 1966 - permanent accommodation at the site and access for larger metallurgical samples
• Mount Isa pilot plant trials on McArthur River ore (1961/66/67/68)
• Circuit development also sought in Australian and overseas laboratories
• By late 1970s to 1980, a complete large pilot plant (50 tonnes/day) existed at the McArthur River lease in the N.T. and a major run in 1977/78 (18 months)*
• Impetus to create company Hydrometallurgy Research Lab (Albion, Brisbane)
*K. Miller, 1980. The McArthur River, N.T., zinc-lead prospect of M.I.M. Holdings, in Woodcock JT (ed.), Mining and Metallurgical Practices in Australasia, The Sir Maurice Mawby Memorial Volume, AusIMM, 182-183.
5 Reason for a new McArthur River Development Program commencing August 1989 (after limited activity for a decade)
• Northern Territory Government indicated a strong desire for development of the deposit
• Otherwise, the leases may be stripped from MIM Holdings
6 Concept for Development Phase commencing 1989 supplied by Brisbane Office of MIM Holdings (Given persistent low metal prices, greenfield projects required mid-teens %Zn in feed to be economic then.) • Metallurgical development to be done by Mineral Processing Research Section at Mount Isa
• Open pit 227Mt 9.2% Zn, 4.1% Pb, 41 ppm Ag reclassified to U/G mine 104Mt 14.1% Zn, 6.4% Pb, 63 ppm Ag
• Modest output U/G mine (no river diversion needed as no open cut) • Selective mining of the highest head grade ore-bodies near the bottom of the sequence (2 O/B, part of 3 O/B and 4 O/B) • Emphasis on Zn, not Pb; Imperial Smelting Furnace (ISF) for concentrate treatment and production of Zn within the project scope
• Less ambitious and potentially much lower capital cost as capital for river diversion avoided, plus lower throughput; elevated zinc assay in feed. 7 The initial metallurgical approaches for the Development Phase commencing in 1989 for McArthur River ore
1. “Coarse” feed to rougher (P80 of 45 µm) to minimize initial grinding of high tonnage stream:
- recovery in rougher step(s) of sphalerite/galena bearing composites mainly - rejection of liberated non sulphide gangue (NGS) and liberated pyrite to final tailing
2. Regrinding of rougher concentrate(s) to a size to be determined which provided sufficient liberation for preparation of a commercial concentrate.
3. Production of the following product(s)
- Zn/Pb bulk concentrate* - Zn/Pb bulk concentrate* + zinc concentrate - other possible product combinations
*for Imperial Smelting Furnace (ISF) technology
8 The McArthur River ore texture (discovered 1955)
9 Comparison of some major fine grained Pb/Zn Deposits – Rougher feed liberation level at stated sizing
Reference: Johnson and Brown, 1990. An Assessment of McArthur River No. 2 Orebody, Research and Development Division of Mount Isa Mines Limited and Met Engineers of Canada, June.
10 Steps in the Development Phase (Laboratory Work)
1. 1989-90: Initial stage, regrinding to 15 µm (ball mill, inert media). Evaluation of concentrate quality (marketing study) – must regrind to 7µm.
2. Mid-1990: Purchase of laboratory batch bead mill (i.e. a stirred mill with inert media) with much increased capability.
3. 1990-91: Second stage of laboratory work with regrind to 7 µm. Allowed preparation of a commercial Zn/Pb bulk concentrate.
11 Development Phase Output: Circuit for McArthur River ore
Typical results:
Pb Zn Ag Silica Conc. 13% 40% 130ppm 4% Grade
Conc. 64% 84% 63% - Recovery
12 Steps in the Development Phase (Pilot Plant Scale Testing of circuit followed by Plant Scale Testing of IsaMill in Existing Concentrators)
1. 1992: Pilot Plant Testing of proposed circuit, including regrinding to 7µm: - 100 litre Netzsch high speed horizontal stirred mill - 400 litre Metprotech vertical stirred mill
Decision by the company to proceed with project. Selected Netzsch technology for regrinding; pilot plant operation revealed extensive changes were needed.
2. 1992-93: Development of IsaMill technology by extensive modification/enlargement of Netzsch bead mill to give a mill of 3000 litres (6 times > largest Netzsch mill). New application: “coarse” product sizing, high tph and low value product.
3. 1993-94: Staged testing of modifications/enlargement in 2 Mount Isa plants.
4. 1995: Start-up of McArthur River operation with 4 x 3000 litre IsaMills.
13 McArthur River operation commenced in 1995 with four IsaMills (3000 litres) for regrinding – a key aspect of metallurgical solution (Note: end of mill nearest camera is the discharge end)
14 Operating Principle (Note: 6 times larger than previous Netzsch horizontal stirred mills, patented product separator, different media/lining materials)
GRINDING MECHANISM & MEDIA RETENTION
Shaft rotating at high speeds generating disc tip Multiple stages of grinding speeds ~ 20 m/s Impeller pumps liquid back into chamber to retain media
Displacement Body Grinding Disks
Product exit
Grinding Shaft Chamber
PATENTED PRODUCT SEPARATOR
Recirculating grinding patterns of media Rotor occur between disks due to variation in Media centrifuged to outside of grinding velocity profile across disks chamber by high centrifugal force generated inside mill CLASSIFICATION ZONE
15 Used with permission of Glencore Technology IsaMillTM Technology Growth (y axis - Cum. Installed Power, x axis - Years)
150
GREEN - M1000 & M500 140 Penasquito II (Goldcorp) BLUE - M 3000 Xstrata Cu-Antapaccay Leinster Nickel (BHPBilliton) RED - M 10,000 Climax Xstrata Cu-EHM 130 Penasquito I (Goldcorp) Red Dog Lonmin EP-C Thompson Creek Anglo Platinum BRPM Cosmos Dominicana Gold Somincor 120 Anglo Platinum PPRust North UFG Boynton Eldorado Gold 110 Anglo Platinum PPRust North Somincor Anglo Platinum Waterval Retrofit UFG 100 Anglo Platinum Waterval Retrofit
90 Anglo Platinum Amandelbult UG2 #1 Anglo Platinum Amandelbult Merensky Plant 80 Anglo Platinum Amandebult UG2 #2 Anglo Platinum Amandebult UG2 #2 70 McArthur River
60 Oceana Gold Prominent Hill Caribou Anglo Platinum Waterval UG2 50 Phu Kham Anglo Platinum PPL-A/B 40 Anglo Platinum PPL-C
Cumulative Installed Power (MW) Installed Cumulative Centerra Gold Kumtor Lonmin EP-C 30 Phelps Dodge Morenci Anglo Platinum WLTRP KCGM Fimiston 20 McArthur River Expansion KCGM Gidgi George Fisher
10 McArthur River M10,000 Development TM Mt Isa Pb Circuit IsaMill Commercialisation 0 1992 1994 1996 1998 2000 2002 2004 2006 2008 2010 2012
Used with permission of Glencore Technology 16 THE PRESENT
17 Developments in applications – IsaMill
Initial Application – Very fine grinding
Later Additional Applications 1. Normal regrinding
2. MIG – Mainstream Inert Grinding (10000 litre mill development)
3. Last stage of primary grinding (feeds up to 300 micron – 80% passing size)
Note: Examples of 1 and 3 exist now at McArthur River site, in addition to very fine regrinding (see later slide).
18 Developments in volume of grinding chamber - IsaMill
M10,000
M3,000
M500
M100
Used with permission of Glencore Technology 19 McArthur River operation – original and expanded circuits Note: Circuit expansions allowed some increase in cleaner stages. * Chadwick, 2013. Giant breaking strides, International Mining, February 2013, 68-83.
* 2.5Mt/yr feed, 5.5Mt/yr after further expansion
20 McArthur River site – two examples of wider applications (Primary grinding section and normal regrinding, beyond original very fine regrinding)
Duty At Commencement After Expansion* (1995) (2013)
1. Last stage of - 2 x M10000 primary grinding
(150 to 45 µm*, P80)
2. Normal regrinding - 2 x M10000
3. Very fine regrinding 4 x M3000 6 x M3000
* Chadwick, 2013. Giant breaking strides, International Mining, February 2013, 68-83.
21 MIG - Mainstream Inert Grinding (Anglo Platinum, South Africa) (Step increase of 4% to 6% in recovery of platinum group elements)
Used with permission of Glencore Technology 22 IsaMill Technology – Platinum Industry, South Africa
• Scale-up to 10,000 litres and 3.0 MW in 2003 (developed jointly with Anglo Platinum), a suitable size for rougher streams in PGE industry.
• In the decade to 2010, the number of stirred mills in PGE industry in S. Africa increased from 0 to 40 (>80% being IsaMills).
M10,000 IsaMillTM
Used with permission of Glencore Technology 23 IsaMills (M10000) – Anglo Platinum – Waterval – South Africa
Used with permission of Glencore Technology 24 Normal Regrinding Duties – two examples
• Phu Kham (Laos, SE Asia) • Prominent Hill (South Australia) – Copper/Gold – Copper Gold – Rougher Concentrate feed (168 tph) – Rougher Concentrate feed (138 tph) – F80 = 106 μm, P80 = 38 μm – F80 = 125 μm, P80 = 24 μm – 2.6 MW M10,000 – 3 MW M10,000 – Commissioned early 2008 – Commissioned early 2009
Used with permission of Glencore Technology 25 Elongation of Zn-Pb ore processing at Mount Isa site by providing higher recoveries for Mount Isa and George Fisher Zn-Pb ores
Pb Circuit (commenced in 1994, development of 3000 litre mill prior to commencement of operation at McArthur River )
Regrinding of lead cleaner block feed*: 20-25 µm to 12 µm (P80 values)
Zn Circuit (George Fisher circuit installation commenced in 1999)
Regrinding of “difficult to liberate sphalerite stream” in the zinc cleaning section**: - regrinding from 12 to 7 µm, provided last stage of regrinding to 12 µm
*Johnson, Gao, Young and Cronin, 1998. Application of the ISAMILL (a horizontal stirred mill) to the Lead-Zinc Concentrator (Mount Isa Mines Ltd) and the Mining Cycle, AusIMM Annual Conference, Mount Isa. **Young and Gao, 2000. Performance of the IsaMills in the Geroge Fisher flowsheet, Seventh Mill Operators’ Conference, AusIMM.
26 Albion Process (Core Resources) – Status of industrial applications
Company Location Concentrate Valuable Status or Project Treated Metal
Glencore Spain McArthur River Zn-Pb-Ag 2010 started-up Glencore Germany McArthur River Zn-Pb-Ag 2011 started-up
Las Lagunas Dominican Rep. Sulphide Au/Ag 2012 started-up GPM Gold Armenia Pyrite/Arsenopyrite Au/Ag 2014 started-up
Note: Preliminary evaluation continues on concentrates from other potential installations.
29 Albion Process, Oxidative Leach Circuit – GPM Gold Project, Armenia
Used with permission of Core Resources 30 Albion process – competing technologies for refractory Au/Ag ores by oxidation of pyrite to allow access to precious metal
1. Pressure oxidation (autoclave)
2. Bio-oxidation
3. Roasting
31 Albion Process – Downstream processing of McArthur River concentrate (bulk Zn-Pb-Ag)
Time Downstream Processing Technology
At commencement (1995) Various Imperial Smelting Furnaces
By 2013 1. Majority to Imperial Smelting Furnaces 2. Smaller quantities to electrolytic zinc smelters for blending with standard zinc concentrates 3. Albion Process Plants* - Glencore smelter in Spain - Glencore smelter in Germany
*www.albion process.com
32 Other effects of the development of the IsaMill on the present metallurgical landscape
1. At the commencement of operation at McArthur River, suppliers did not have cheap manufactured inert media suitable for the IsaMILL in the mineral industry in their range.
The increasing sales of IsaMILLS was a primary cause for reversal of this.
There have also been technology improvements in the media.
2. Experiences in pumping of the finely reground and stable froths* in the early stages of operation of the plant at McArthur River resulted in major improvements in commercial pumping technology (Peter Woodall).
33 THE FUTURE
1. Development of larger IsaMills (Glencore Technology, Brisbane)
2. Establishment of the upper limit for the feed size to the last stage of primary grinding
3. Application of existing finer regrinding capability e.g. 1 to 5 µm
4. Increased application of regrinding to 15 - 20 µm region
5. Further applications of the Albion Process (hydrometallurgy) by Core Resources (Albion, Brisbane)
34 Acknowledgements Glencore Technology and Core Resources for support of this presentation. (Slides from Glencore Technology and Core Resources are acknowledged gratefully.)
The important input and effort of many staff at Mount Isa Mines Limited and at NETZSCH Feinmahltechnik GmbH in the initial phases of this work is acknowledged fully.
Special mention is made of J. Andreatidis and P. Woodall from Mount Isa Mines Ltd. The very important contributions of M. Young, M. Duffy, R. Alford, B. Cronin, B. Mullan, R. Espinosa, M. Gao, M. Larsen and W. Onton are also acknowledged.
References Logan, Leung and Karelse, 1993. The McArthur River Project, Proc. Int. Symp. on Zinc (World Zinc 1993), AusIMM and CIMM, Hobart. Enderle, Woodall, Duffy and Johnson, 1997. Stirred mill technology for regrinding McArthur River and Mount Isa zinc/lead ores, XX IMPC, Aachen, Germany. Johnson, Gao, Young and Cronin, 1998. Application of the ISAMILL (a horizontal stirred mill) to the Lead-Zinc Concentrator (Mount Isa Mines Ltd) and the Mining Cycle, AusIMM Annual Conference, Mount Isa. Andreatidis, 1995. Breakage mechanisms and resulting mineral liberation in a bead mill, M. Eng. Sc. Thesis, Dept. of Min. and Metall. Eng., Univ. of Q’ld. 35 IMPROVING OPERATIONAL EFFECTIVENESS TECHNICAL EXPERTISE • ONGOING SUPPORT COMMERCIAL SERVICES PROFESSIONAL DEVELOPMENT
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