> Mineral Processing > Engineering Design > Training > Specialist Services > RESOURCE PROJECTS > TECHNOLOGY > INTEGRATED SERVICES > Mineral Processing > Engineering Design > Training > Specialist Services Ph: +61 8 9421 9000 Fax: +61 8 9325 8311 Email: [email protected]Web: www.metsengineering.com PO Box 5778, ST GEORGES TCE, WA 6832 AUSTRALIA Materials Handling Week 2013 High Clay Ores – A Mineral Processing Nightmare John Visser June 2013
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John Visser, Mineral Engineering Technical Services Pty Ltd (METS) - Examining High Clay Ores to Overcome Processing Nightmares
John Visser, Metallurgical Director, Mineral Engineering Technical Services Pty Ltd (METS) delivered this presentation at the 10th Annual Bulk Materials Handling conference 2013. This conference is an expert led forum on the engineering behind the latest expansions and upgrades of bulk materials facilities. It also evaluates the latest engineering feats that are creating record levels of throughput whilst minimising downtime.
For more information on this conference, please vist http://www.informa.com.au/bmh2014
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> M i n e r a l P r o c e s s i n g > E n g i n e e r i n g D e s i g n > T r a i n i n g > S p e c i a l i s t S e r v i c e s > RESOURCE PROJECTS > TECHNOLOGY > INTEGRATED SERVICES > Mineral Processing > Engineering Design > Training > Specialist Services
Ph: +61 8 9421 9000 Fax: +61 8 9325 8311 Email: [email protected] Web: www.metsengineering.com PO Box 5778, ST GEORGES TCE, WA 6832 AUSTRALIA
Materials Handling Week 2013
High Clay Ores – A Mineral Processing Nightmare
John Visser June 2013
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Clay minerals exist in the areas above the water table but can in some instances exist below it
The reaction of feldspars and water to form kaolinite involves the exchange of cations and produces a clay mineral
This makes it difficult to clearly define the zone of oxidation and therefore selectively mine these zones. Even mining fresh ore there are occasional patches of weathered clay ore within the sulphide zone
Must recognise and test zones at the development stage
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Hydrothermal alteration results from the interaction of hot waters with rocks to form clay minerals
This is not uncommon in Epithermal deposits and results in clays persisting at depths which would not be expected
The phenomena of hard quartz rock with interspersed clay (5 to 15% clay) as a result of hydrothermal fluids is quite deceptive with regards to how the rock will process
Source: METS Library (2013)
Casposo Ore
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through the jaw crusher and into a passive stockpile so it can be fed to a ball mill using a front end loader is one solution
Secondary crushing and screening may not be possible particularly if the ore is wet and sticky. Cone crushers bridge and screens become blinded
Putting clay ores into bins or stockpile with reclaim tunnels can be a disaster. They simply don’t work. Feeding direct into SAG mills is a much better option if this suits the process
Scrubbers ahead of crushing
Source: FLSmidth Website (2013)
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At the Kurara gold project the ore was so viscous it would not flow out of the mill even with lower densities
Also cyclone efficiency is negatively affected resulting in a less sharp separation. Clays affect the grinding efficiency necessitating operating the mill with a lower density to flush the clay out of the mill
The use of viscosity modifiers or caustic soda rather than lime will mitigate these effects
Source: METS Library (2013)
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High clay ores require agglomeration with cement in an agglomeration drum and time to cure before stacking
If agglomeration is not used the percolation will be very low and effective recovery from the heap very low. The cement addition rate required is critical and can affect the economics of the process
Source: METS Library (2013)
Source: METS Library (2013)
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The mineral sands industry uses hydrosizers up front to remove clays from the mineral sands feed. Clays negatively impact on the separation process using spirals
Beenup
Source: METS Library (2013)
Source: Allmineral Website
(2013)
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For high clay ores TUNRA type testing to determine rill angles, angles of repose and materials handling characteristics is a must
Only apron feeders are effective feeders with high clay ores. The use of stockpiles is not possible because of rat holing and the difficulties getting the ore to flow in a stockpile or bin is extreme
Conveying is also difficult requiring the use of belt washing stations plus increased tracking issues
Source: METS Library (2013)
Allied Gold - Simberi
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Understanding the geology, mineralogy and correctly selecting representative samples of the ore to be processed is critical in getting the mineral, processing right
Clays have the potential if not recognised to destroy project economics. Testing at an early stage of representative ore samples is critical
The presence of clays in hard rock comes as a surprise if not fully understood. Similarly waste dilution from country rock containing clay can adversely affect the process. There are some solutions which assist in processing ores but don’t negate all of the difficulties
The presence of clays has a major influence on the process selection and equipment used in the final flowsheet. The industry has paid a heavy price on a number of projects where the clay was not recognised or the process plant was based on a hard rock design which later proved to be totally unsuitable
Trying to mitigate the impact of clay on the process if the percentage of clay in the feed cannot be controlled is a mineral processing nightmare
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> ASU. 2007. Healing Clay. [ONLINE] Available at: http://researchmatters.asu.edu/stories/healing-clay-906. [Accessed 13 November 12]
> Ehlers, Ernest G. and Blatt, Harvey (1982). 'Petrology, Igneous, Sedimentary, and Metamorphic' San Francisco: W.H. Freeman and Company. ISBN 0-7167-1279-2
> Guggenheim, Stephen; Martin, R. T. (1995), "Definition of clay and clay mineral: Journal report of the AIPEA nomenclature and CMS nomenclature committees", Clays and Clay Minerals 43 (2): 255–256, doi:10.1346/CCMN.1995.0430213 . Clay mineral nomenclature American Mineralogist
> Hillier S. (2003) Clay Mineralogy. pp 139–142 In: Middleton G.V., Church M.J., Coniglio M., Hardie L.A. and Longstaffe F.J.(Editors) Encyclopedia of sediments and sedimentary rocks. Kluwer Academic Publishers, Dordrecht
> Mining Technology. 2012. Flotation, Agglomeration and Filtering. [ONLINE] Available at: http://www.mining-technology.com/contractors/filtering/flsmidth/flsmidth1.html. [Accessed 13 November 12]
> SKC . 2013. developments in inhalable samples. [ONLINE] Available at: http://www.skcinc.com/headlns/perspective.asp. [Accessed 28 May 13]
> IM Mining. 2011. Canadian acquisition primes Stewart Group for expansion in metals and minerals analysis. [ONLINE] Available at: http://www.im-mining.com/2011/02/02/canadian-acquisition-primes-stewart-group-for-expansion-in-metals-and-minerals-analysis/. [Accessed 28 May 13]
> FEI. 2013. QEMSCAN. [ONLINE] Available at: http://www.fei-natural-resources.com/products/qemscan.aspx. [Accessed 28 May 13].
> AJM Online. 2011. High Clay Ores, A Mineral Processing Nightmare. [ONLINE] Available at: http://www.fei-natural-resources.com/products/qemscan.aspx. [Accessed 28 May 13]
> AllMineral. 2013. allmineral goes Down Under: contracts still rolling in from Australia. [ONLINE] Available at: http://www.allmineral.com/gb/newsbox.php?number=4. [Accessed 28 May 13].
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