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Overview of the Gold Mining Industry and Major Gold Deposits
Chapter 2
Overview of the Gold Mining Industry and Major Gold Deposits M.D. Adams Fugue Pte Ltd, Singapore
More gold has been mined from the thoughts of men than has been taken from the earth. Napoleon Hill, 1883e1970 Gold and silver, like other commodities, have an intrinsic value, which is not arbitrary, but is dependent on their scarcity, the quantity of labour bestowed in procuring them, and the value of the capital employed in the mines which produce them. David Ricardo, 1772e1823 I’m a dirt person. I trust the dirt. I don’t trust diamonds and gold. Eartha Kitt, 1927e2008
1. INTRODUCTION Gold has been a sought-after metal since it was first encountered and crudely worked. As a noble, readily workable metal that does not easily tarnish or corrode, it has enduring inherent value. Since the first edition of this book, the price of gold has increased fourfold, from about $400/oz in 2005 to a high of $1800/oz in late 2011, dropping to a price around publication in early 2016 of around $1200/oz, as illustrated in Figure 2.1. Unlike other metals, for which prices are dictated by commodity-driven supplyedemand factors, the price of gold is influenced by global economic factors such as interest rates and inflation, noting that investor sentiment is fickle and not easy to forecast. The impact of the price of gold on successful gold exploration discovery and production therefore should not be underemphasized. In response to increases in operating costs and fluctuations in the price of gold, many companies are responding with short-term fixes, such as reducing discretionary items including overhead and spending on exploration, and deferring capital expenditure on growth projects. A more drastic yet common response has been to mine fewer but more profitable orebodies, resulting in the postponement of new mine, pit, or shaft development. The net result is that within a few years, the gold industry may experience declining production from the closure of existing mines and a decrease in new mine startups. However, this presents an opportunity for mine owners in conjunction with process technology and engineering providers for brownfield expansions, given the capital sunk in existing mines, to lift production at lower costs and potentially higher recoveries.
2. GOLD DISCOVERY AND DEPOSITS It was reported (Mining Journal, 2012) that a study by the Metals Economics Group, entitled Strategies for Gold Reserves Replacement: The Costs of Finding and Acquiring Gold, revealed a total of 99 new gold discoveries between 1997 and 2011, each of which was at least 2 million oz (Moz) Au. Assuming 75% resource conversion and 90% gold
Gold Ore Processing. Mike D. Adams (Editor), http://dx.doi.org/10.1016/B978-0-444-63658-4.00002-5 Copyright © 2016 Elsevier B.V. All rights reserved.
25
26
PART | I Project Development
2000 1800
Gold Price, US$/oz
1600 1400 1200 1000 800 600 400 200 0
FIGURE 2.1 Historical gold prices 2000e2015.
recovery, these 99 discoveries could potentially replace only 56% of the estimated gold mined during this period, assuming they were economical to mine. Discoveries in the United States made up 18% of the total, with Canada at 10% and Australia at 8%. The data are analyzed and presented on a regional basis in Figure 2.2, showing that the Americas comprised about half the gold contained in discoveries over that period, with some 20% in Africa, 12% in Australasia, and 10% in the Middle East. Contained gold in several gold discoveries is impressive, such as Pebble in Alaska, United States, containing large quantities of Cu, Au, Mo, and Ag, inclusive of some 70 Moz Au in measured and indicated resources (Northern Dynasty Minerals Ltd, 2016). The US Environmental Protection Agency proposed development restrictions at Pebble under Section 404(c) of the Clean Water Act before the owner proposed a development plan or submitted permit applications including an environmental impact statement. The company is assessing potential impacts of the proposed restrictions on its development plan. Sukhoi Log in Siberia, Russia, is estimated to contain more than 60 Moz Au (Ferreira-Marques, 2012). The deposit was discovered over half a century ago, but its development was held up by the collapse of the Soviet Union, which delayed the construction of bridges, roads, and associated infrastructure. Mineralization is a quartzepyriteegold carbonate disseminated in black shale with minor base and platinum group metals (Wood and Popov, 2006). Also worthy of mention is the KSM deposit (Seabridge Gold, 2016), with proven and probable reserves of 38.2 Moz Au as well as large quantities of Cu and Ag. Such major deposits often share similar challenges, including opposition from nongovernmental
Russia
2%
North and Central America
3%
31%
Europe Middle East
Africa
10%
20% South America
16%
Australasia
12%
FIGURE 2.2 Gold in reserves, resources, and past production in major gold discoveries (total, 743 Moz Au) by region, 1997e2011. Adapted from data supplied in Metals Economics Group (2012).
Overview of the Gold Mining Industry and Major Gold Deposits Chapter | 2
27
Time from Discovery to Producon, y
30
25
20
15
10
5
0
1985
1990
1995
2000
2005
2010
2015
2020
2025
2030
2035
FIGURE 2.3 Time from discovery to production. Adapted from data supplied in Metals Economics Group (2012).
organizations and their remote and extremely cold locations. Perhaps the largest challenge is finding a suitable joint venture partner to assist with the capital finance needed to advance the project to an operating mine with eventual positive cash flow. In an assessment of gold discoveries, SNL Metals and Mining (2014) has determined that the time it takes to bring a deposit into production is also increasing significantly, slowing the rate at which production is replaced. The time from discovery to production increased from 8 years for 27 new mines between 1985 and 1995 to 11 years for 57 new mines between 1996 and 2005, and further to 18 years for 111 new mines between 2006 and 2013, as depicted in Figure 2.3. If this trend continues, lag time from discovery to production could reach more than 25 years by 2025, with a potentially material effect on overall project net present value.
3. GOLD PRODUCTION Gold is produced at both large operations owned by major companies and small artisanal works, often located alongside the major mine sites. It is informative to assess the world’s 20 largest gold-producing mines in terms of gold production. For the purpose of this exercise, four types of gold deposits have been selected. This segmentation is based on the processing route, which in turn is dictated by the mineralogy and grade of the deposit, as well as the presence of additional value metals: 1. Free-milling (economically amenable to direct cyanidation and recovery by carbon in pulp/carbon in leach (CIP/CIL) or Merrill-Crowe) 2. Heap-leachable (economic by heap leaching but not tank cyanidation) 3. Concentrate sale (co-products are present, rendering a concentrate smeltable, or direct sale of concentrate deemed acceptably economic provided that off-takers are available) 4. Refractory (not amenable to direct cyanidation or concentrate sale; requires preprocessing before leaching and recovery) Gold production from refractory deposits currently contributes a significant component of global gold production, based on 2011 data (Mining Journal, 2012). Of the 2630 tons (84.6 Moz) of total world gold production in that year (U.S. Geological Survey, 2014), it may be estimated that about a quarter was produced from refractory deposits and about half via free-milling cyanidation including mainly CIP/CIL, with about 15% by heap leaching and 10% by flotation. Figure 2.4 shows a breakdown of the top 20 global gold producers ranked by output in 2011 (accounting for about 20% of global gold production), by production and processing route. Gold produced by flotation in 2011 (three of the operations) was mainly as a by-product of copper production. Of the top 20 gold operations in 2011, eight were processing refractory ores, five were large heap-leach operations, and three were free-milling, comprising cyanidation and CIP/CIL.
28
PART | I Project Development
2000
Gold Producon, koz
1800
Concentrate
Cyanidaon
Heap Leach
Refractory
1600 1400
1200 1000 800 600 400 200 0
FIGURE 2.4 Top 20 global gold producers in 2011. Adapted from data supplied in Mining Journal (2012).
FIGURE 2.5 Top 20 global gold producers in 2011. Adapted from data supplied in Mining Journal (2012).
Outcomes of segmentation analysis of the gold ore processing industry in 2011 are summarized in Figure 2.5. Of the top 20 gold-producing mines, most (38%) were from refractory gold ores, followed by heap leaching (30%) and freemilling cyanidation/CIP (CIL) (18%), and with 14% as by-product gold from the smelting of copper concentrates. It is useful to consider the process routes involved in processing these refractory ores. Over half of the refractory gold from the top 20 operations in 2011 was produced by roasting, 10% by pressure oxidation (POX), 5% by ultra-fine grinding (UFG), and 3% by bacterial oxidation. In the intervening 5 years since the 2011 analysis data, some interesting changes have occurred in this sector, and new operations have come on-stream: l
l
l
KCGM (Western Australia) has shut down their fluid-bed roaster and installed additional IsaMill UFG capacity (Lucas, 2014). Goldstrike (Nevada, United States) has commissioned a POXethiosulphate leacheRIP circuit to treat double-refractory ore previously only treatable by roasting (see Chapter 50 for more detail). Some examples for illustration of major startups subsequent to 2011 include Turquoise Hill’s massive CueAu porphyry mine, Oyu Tolgoi, which has since been commissioned, producing about 18 tons (about 579 thousand oz (koz)) of gold in 2014. Barrick Gold’s Pueblo Viejo operation in the Dominican Republic (about 1125 koz Au in 2014), including POX for the treatment of refractory gold concentrate, has commenced operations. Goldcorps’s Penasquito mine has been commissioned (about 579 koz Au in 2014) and treats ZnePbeAgeAu polymetallic ore that is subjected to flotation, to make concentrates for smelting. Kinross Gold’s Kupol operation underwent a major expansion and treats high-silveregold ore by cyanidation and Merrill-Crowe zinc cementation.
Overview of the Gold Mining Industry and Major Gold Deposits Chapter | 2
29
Kupol
Olimpiada Red Lake Kumtor
Newmont Nevada
Muruntau
Goldstrike Cortez Penasquito
Oyu Tolgoi
Zijinshan
Pueblo Viejo Ahofo
Refractory Heap Leach Cyanidation Concentrate Bioleach Roast
Yanacocha
Tarkwa
Lagunas Norte Veladero
Lihir Grasberg Telfer Super Pit
Kloof-Driefontein
Cadia Hill
Boddington
UFG POX
FIGURE 2.6 Global location and processing routes of top 20 global gold producers in 2011; selected major additional producers commissioned between 2012 and 2015 are shown in dotted boxes. Adapted from data in Mining Journal (2013).
The locations of these 2011 top 20 producing gold mines across the globe are depicted in Figure 2.6. Several major plants have been commissioned after 2011 and have come on-stream; key examples of these are included in dotted boxes. Several features are apparent in this widespread global dispersion of gold deposits and mines. The four major ore type segments as allocated in this overview are distributed widely across the globe, as are the different process routes. Three of the refractory operations are located in the Carlin Trend in the United States and are partly made up of doublerefractory ore but are primarily conventional refractory ores. Major deposits of refractory gold are located around the Super Pit in Western Australia, whereas large producing refractory gold deposits occur at Kumtor and Olimpiada in central Asia. Several of the operations and extractive processes mentioned in this chapter are discussed in more detail throughout this book. The segmentation method for dividing ore types via their major processing routes is not a hard and fast rule, but seems a convenient way of differentiating ore mineralogy, grade, and valuable co-elements on the basis of plant practice.
REFERENCES Ferreira-Marques, C., December 20, 2012. Sukhoi Log Gold Development Could Propel Russia to World No.1, Mineweb. http://www.mineweb.com/ archive/sukhoi-log-gold-development-could-propel-russia-to-world-no-1/. Accessed 14.02.16. Lucas, J., February 6, 2014. KCGM to Shut Down Gidji Roaster. The West Australian Regional. https://au.news.yahoo.com/thewest/regional/goldfields/a/ 21297839/kcgm-to-shut-down-gidji-roaster/. Accessed 13.02.16. Mining Journal, August 2012. Gold Exploration, Mining Journal Special Publication, 62 pp. Mining Journal, September 2013. Gold, Mining Journal Special Publication, 46 pp. Metals Economics Group, July 17, 2012. MEG’s Gold Reserves Replacement Strategies, Cited in: Gold Discoveries Not Keeping Pace with Mined Production, Mining.Com. http://www.mining.com/gold-discoveries-not-keeping-pace-with-mined-production/. Accessed 14.02.16. Northern Dynasty Minerals Ltd, 2016. Pebble Overview. http://www.northerndynastyminerals.com/ndm/Pebble.asp. Accessed 14.02.16. SNL Metals & Mining, July 18, 2014. Fewer Discoveries, Slower Development Weigh on Gold Industry, Mining.Com. http://www.mining.com/web/ fewer-discoveries-slower-development-weigh-on-gold-industry/. Accessed 14.02.16. Seabridge Gold, 2016. Factsheet http://seabridgegold.net/factsheet.php. Accessed 14.02.16 U.S. Geological Survey, 2014. Gold statistics. In: Kelly, T.D., Matos, G.R. (Eds.), Historical Statistics for Mineral and Material Commodities in the United States, U.S. Geological Survey Data Series, vol. 140. http://minerals.usgs.gov/minerals/pubs/historical-statistics/. Accessed 13.02.16. Wood, B.L., Popov, N.P., 2006. The giant Sukhoi Log gold deposit, Siberia. Russ. Geol. Geophys. 47 (3), 315e341.
30
PART | I Project Development
Mike D. Adams has over 30 years of diverse experience in the development and assessment of metallurgical projects, including processes for gold, platinum (PGE), uranium, and base and rare metals recovery. He consulted independently for over 10 years with his company, Mutis Liber Pty Ltd., and was also previously director of Rockwell Minerals Ltd. (now merged with ASX-listed Elementos Ltd.), metallurgical manager with SGS Lakefield Oretest, and head of Process and Environmental Chemistry at Mintek. Mike completed BSc(Hons) and MSc degrees in Applied Chemistry at the University of the Witwatersrand, and later a PhD with a dissertation on The Chemistry of the Carbon-in-Pulp Process and a DSc(Eng) Senior Doctorate of Science in Engineering, with a dissertation on Advances in the Processing of Gold Ores. Mike is a Chartered Professional (Metallurgy) and is a Fellow of the Australian and the South African Institutes of Mining and Metallurgy, as well as the Royal Society of Chemistry. He is Associate Editor for Hydrometallurgy journal and an editorial board member of Minerals Engineering journal, and has edited three books, including Advances in Gold Ore Processing (2005, Elsevier), the first edition of the current second edition volume of Gold Ore Processing, 2e (2016, Elsevier). Dr. Adams is widely published in metallurgy and chemistry, including some 50 papers on gold processing. He has made a significant contribution to the chemistry and optimization of the carbon-in-pulp process for gold recovery, for which he received the Raikes Gold Medal from the South African Chemical Institute and two silver medals from the South African Institute of Mining and Metallurgy. Notable contributions have included project management and metallurgy of integrated pilot-plant campaigns for definitive feasibility studies on the processing of nickel laterites and sulfides, PGM concentrates, gold ores, and zirconiumeniobiume rare earth element ores. Currently director of Fugue Pte Ltd., Mike has been assisting from the early stages with the development of the Kell Process, a hydrometallurgical alternative to smelting, which is his current focus.
Overview of the Gold Mining Industry and Major Gold Deposits M.D. Adams Fugue Pte Ltd, Singapore
More gold has been mined from the thoughts of men than has been taken from the earth. Napoleon Hill, 1883e1970 Gold and silver, like other commodities, have an intrinsic value, which is not arbitrary, but is dependent on their scarcity, the quantity of labour bestowed in procuring them, and the value of the capital employed in the mines which produce them. David Ricardo, 1772e1823 I’m a dirt person. I trust the dirt. I don’t trust diamonds and gold. Eartha Kitt, 1927e2008
1. INTRODUCTION Gold has been a sought-after metal since it was first encountered and crudely worked. As a noble, readily workable metal that does not easily tarnish or corrode, it has enduring inherent value. Since the first edition of this book, the price of gold has increased fourfold, from about $400/oz in 2005 to a high of $1800/oz in late 2011, dropping to a price around publication in early 2016 of around $1200/oz, as illustrated in Figure 2.1. Unlike other metals, for which prices are dictated by commodity-driven supplyedemand factors, the price of gold is influenced by global economic factors such as interest rates and inflation, noting that investor sentiment is fickle and not easy to forecast. The impact of the price of gold on successful gold exploration discovery and production therefore should not be underemphasized. In response to increases in operating costs and fluctuations in the price of gold, many companies are responding with short-term fixes, such as reducing discretionary items including overhead and spending on exploration, and deferring capital expenditure on growth projects. A more drastic yet common response has been to mine fewer but more profitable orebodies, resulting in the postponement of new mine, pit, or shaft development. The net result is that within a few years, the gold industry may experience declining production from the closure of existing mines and a decrease in new mine startups. However, this presents an opportunity for mine owners in conjunction with process technology and engineering providers for brownfield expansions, given the capital sunk in existing mines, to lift production at lower costs and potentially higher recoveries.
2. GOLD DISCOVERY AND DEPOSITS It was reported (Mining Journal, 2012) that a study by the Metals Economics Group, entitled Strategies for Gold Reserves Replacement: The Costs of Finding and Acquiring Gold, revealed a total of 99 new gold discoveries between 1997 and 2011, each of which was at least 2 million oz (Moz) Au. Assuming 75% resource conversion and 90% gold
Gold Ore Processing. Mike D. Adams (Editor), http://dx.doi.org/10.1016/B978-0-444-63658-4.00002-5 Copyright © 2016 Elsevier B.V. All rights reserved.
25
26
PART | I Project Development
2000 1800
Gold Price, US$/oz
1600 1400 1200 1000 800 600 400 200 0
FIGURE 2.1 Historical gold prices 2000e2015.
recovery, these 99 discoveries could potentially replace only 56% of the estimated gold mined during this period, assuming they were economical to mine. Discoveries in the United States made up 18% of the total, with Canada at 10% and Australia at 8%. The data are analyzed and presented on a regional basis in Figure 2.2, showing that the Americas comprised about half the gold contained in discoveries over that period, with some 20% in Africa, 12% in Australasia, and 10% in the Middle East. Contained gold in several gold discoveries is impressive, such as Pebble in Alaska, United States, containing large quantities of Cu, Au, Mo, and Ag, inclusive of some 70 Moz Au in measured and indicated resources (Northern Dynasty Minerals Ltd, 2016). The US Environmental Protection Agency proposed development restrictions at Pebble under Section 404(c) of the Clean Water Act before the owner proposed a development plan or submitted permit applications including an environmental impact statement. The company is assessing potential impacts of the proposed restrictions on its development plan. Sukhoi Log in Siberia, Russia, is estimated to contain more than 60 Moz Au (Ferreira-Marques, 2012). The deposit was discovered over half a century ago, but its development was held up by the collapse of the Soviet Union, which delayed the construction of bridges, roads, and associated infrastructure. Mineralization is a quartzepyriteegold carbonate disseminated in black shale with minor base and platinum group metals (Wood and Popov, 2006). Also worthy of mention is the KSM deposit (Seabridge Gold, 2016), with proven and probable reserves of 38.2 Moz Au as well as large quantities of Cu and Ag. Such major deposits often share similar challenges, including opposition from nongovernmental
Russia
2%
North and Central America
3%
31%
Europe Middle East
Africa
10%
20% South America
16%
Australasia
12%
FIGURE 2.2 Gold in reserves, resources, and past production in major gold discoveries (total, 743 Moz Au) by region, 1997e2011. Adapted from data supplied in Metals Economics Group (2012).
Overview of the Gold Mining Industry and Major Gold Deposits Chapter | 2
27
Time from Discovery to Producon, y
30
25
20
15
10
5
0
1985
1990
1995
2000
2005
2010
2015
2020
2025
2030
2035
FIGURE 2.3 Time from discovery to production. Adapted from data supplied in Metals Economics Group (2012).
organizations and their remote and extremely cold locations. Perhaps the largest challenge is finding a suitable joint venture partner to assist with the capital finance needed to advance the project to an operating mine with eventual positive cash flow. In an assessment of gold discoveries, SNL Metals and Mining (2014) has determined that the time it takes to bring a deposit into production is also increasing significantly, slowing the rate at which production is replaced. The time from discovery to production increased from 8 years for 27 new mines between 1985 and 1995 to 11 years for 57 new mines between 1996 and 2005, and further to 18 years for 111 new mines between 2006 and 2013, as depicted in Figure 2.3. If this trend continues, lag time from discovery to production could reach more than 25 years by 2025, with a potentially material effect on overall project net present value.
3. GOLD PRODUCTION Gold is produced at both large operations owned by major companies and small artisanal works, often located alongside the major mine sites. It is informative to assess the world’s 20 largest gold-producing mines in terms of gold production. For the purpose of this exercise, four types of gold deposits have been selected. This segmentation is based on the processing route, which in turn is dictated by the mineralogy and grade of the deposit, as well as the presence of additional value metals: 1. Free-milling (economically amenable to direct cyanidation and recovery by carbon in pulp/carbon in leach (CIP/CIL) or Merrill-Crowe) 2. Heap-leachable (economic by heap leaching but not tank cyanidation) 3. Concentrate sale (co-products are present, rendering a concentrate smeltable, or direct sale of concentrate deemed acceptably economic provided that off-takers are available) 4. Refractory (not amenable to direct cyanidation or concentrate sale; requires preprocessing before leaching and recovery) Gold production from refractory deposits currently contributes a significant component of global gold production, based on 2011 data (Mining Journal, 2012). Of the 2630 tons (84.6 Moz) of total world gold production in that year (U.S. Geological Survey, 2014), it may be estimated that about a quarter was produced from refractory deposits and about half via free-milling cyanidation including mainly CIP/CIL, with about 15% by heap leaching and 10% by flotation. Figure 2.4 shows a breakdown of the top 20 global gold producers ranked by output in 2011 (accounting for about 20% of global gold production), by production and processing route. Gold produced by flotation in 2011 (three of the operations) was mainly as a by-product of copper production. Of the top 20 gold operations in 2011, eight were processing refractory ores, five were large heap-leach operations, and three were free-milling, comprising cyanidation and CIP/CIL.
28
PART | I Project Development
2000
Gold Producon, koz
1800
Concentrate
Cyanidaon
Heap Leach
Refractory
1600 1400
1200 1000 800 600 400 200 0
FIGURE 2.4 Top 20 global gold producers in 2011. Adapted from data supplied in Mining Journal (2012).
FIGURE 2.5 Top 20 global gold producers in 2011. Adapted from data supplied in Mining Journal (2012).
Outcomes of segmentation analysis of the gold ore processing industry in 2011 are summarized in Figure 2.5. Of the top 20 gold-producing mines, most (38%) were from refractory gold ores, followed by heap leaching (30%) and freemilling cyanidation/CIP (CIL) (18%), and with 14% as by-product gold from the smelting of copper concentrates. It is useful to consider the process routes involved in processing these refractory ores. Over half of the refractory gold from the top 20 operations in 2011 was produced by roasting, 10% by pressure oxidation (POX), 5% by ultra-fine grinding (UFG), and 3% by bacterial oxidation. In the intervening 5 years since the 2011 analysis data, some interesting changes have occurred in this sector, and new operations have come on-stream: l
l
l
KCGM (Western Australia) has shut down their fluid-bed roaster and installed additional IsaMill UFG capacity (Lucas, 2014). Goldstrike (Nevada, United States) has commissioned a POXethiosulphate leacheRIP circuit to treat double-refractory ore previously only treatable by roasting (see Chapter 50 for more detail). Some examples for illustration of major startups subsequent to 2011 include Turquoise Hill’s massive CueAu porphyry mine, Oyu Tolgoi, which has since been commissioned, producing about 18 tons (about 579 thousand oz (koz)) of gold in 2014. Barrick Gold’s Pueblo Viejo operation in the Dominican Republic (about 1125 koz Au in 2014), including POX for the treatment of refractory gold concentrate, has commenced operations. Goldcorps’s Penasquito mine has been commissioned (about 579 koz Au in 2014) and treats ZnePbeAgeAu polymetallic ore that is subjected to flotation, to make concentrates for smelting. Kinross Gold’s Kupol operation underwent a major expansion and treats high-silveregold ore by cyanidation and Merrill-Crowe zinc cementation.
Overview of the Gold Mining Industry and Major Gold Deposits Chapter | 2
29
Kupol
Olimpiada Red Lake Kumtor
Newmont Nevada
Muruntau
Goldstrike Cortez Penasquito
Oyu Tolgoi
Zijinshan
Pueblo Viejo Ahofo
Refractory Heap Leach Cyanidation Concentrate Bioleach Roast
Yanacocha
Tarkwa
Lagunas Norte Veladero
Lihir Grasberg Telfer Super Pit
Kloof-Driefontein
Cadia Hill
Boddington
UFG POX
FIGURE 2.6 Global location and processing routes of top 20 global gold producers in 2011; selected major additional producers commissioned between 2012 and 2015 are shown in dotted boxes. Adapted from data in Mining Journal (2013).
The locations of these 2011 top 20 producing gold mines across the globe are depicted in Figure 2.6. Several major plants have been commissioned after 2011 and have come on-stream; key examples of these are included in dotted boxes. Several features are apparent in this widespread global dispersion of gold deposits and mines. The four major ore type segments as allocated in this overview are distributed widely across the globe, as are the different process routes. Three of the refractory operations are located in the Carlin Trend in the United States and are partly made up of doublerefractory ore but are primarily conventional refractory ores. Major deposits of refractory gold are located around the Super Pit in Western Australia, whereas large producing refractory gold deposits occur at Kumtor and Olimpiada in central Asia. Several of the operations and extractive processes mentioned in this chapter are discussed in more detail throughout this book. The segmentation method for dividing ore types via their major processing routes is not a hard and fast rule, but seems a convenient way of differentiating ore mineralogy, grade, and valuable co-elements on the basis of plant practice.
REFERENCES Ferreira-Marques, C., December 20, 2012. Sukhoi Log Gold Development Could Propel Russia to World No.1, Mineweb. http://www.mineweb.com/ archive/sukhoi-log-gold-development-could-propel-russia-to-world-no-1/. Accessed 14.02.16. Lucas, J., February 6, 2014. KCGM to Shut Down Gidji Roaster. The West Australian Regional. https://au.news.yahoo.com/thewest/regional/goldfields/a/ 21297839/kcgm-to-shut-down-gidji-roaster/. Accessed 13.02.16. Mining Journal, August 2012. Gold Exploration, Mining Journal Special Publication, 62 pp. Mining Journal, September 2013. Gold, Mining Journal Special Publication, 46 pp. Metals Economics Group, July 17, 2012. MEG’s Gold Reserves Replacement Strategies, Cited in: Gold Discoveries Not Keeping Pace with Mined Production, Mining.Com. http://www.mining.com/gold-discoveries-not-keeping-pace-with-mined-production/. Accessed 14.02.16. Northern Dynasty Minerals Ltd, 2016. Pebble Overview. http://www.northerndynastyminerals.com/ndm/Pebble.asp. Accessed 14.02.16. SNL Metals & Mining, July 18, 2014. Fewer Discoveries, Slower Development Weigh on Gold Industry, Mining.Com. http://www.mining.com/web/ fewer-discoveries-slower-development-weigh-on-gold-industry/. Accessed 14.02.16. Seabridge Gold, 2016. Factsheet http://seabridgegold.net/factsheet.php. Accessed 14.02.16 U.S. Geological Survey, 2014. Gold statistics. In: Kelly, T.D., Matos, G.R. (Eds.), Historical Statistics for Mineral and Material Commodities in the United States, U.S. Geological Survey Data Series, vol. 140. http://minerals.usgs.gov/minerals/pubs/historical-statistics/. Accessed 13.02.16. Wood, B.L., Popov, N.P., 2006. The giant Sukhoi Log gold deposit, Siberia. Russ. Geol. Geophys. 47 (3), 315e341.
30
PART | I Project Development
Mike D. Adams has over 30 years of diverse experience in the development and assessment of metallurgical projects, including processes for gold, platinum (PGE), uranium, and base and rare metals recovery. He consulted independently for over 10 years with his company, Mutis Liber Pty Ltd., and was also previously director of Rockwell Minerals Ltd. (now merged with ASX-listed Elementos Ltd.), metallurgical manager with SGS Lakefield Oretest, and head of Process and Environmental Chemistry at Mintek. Mike completed BSc(Hons) and MSc degrees in Applied Chemistry at the University of the Witwatersrand, and later a PhD with a dissertation on The Chemistry of the Carbon-in-Pulp Process and a DSc(Eng) Senior Doctorate of Science in Engineering, with a dissertation on Advances in the Processing of Gold Ores. Mike is a Chartered Professional (Metallurgy) and is a Fellow of the Australian and the South African Institutes of Mining and Metallurgy, as well as the Royal Society of Chemistry. He is Associate Editor for Hydrometallurgy journal and an editorial board member of Minerals Engineering journal, and has edited three books, including Advances in Gold Ore Processing (2005, Elsevier), the first edition of the current second edition volume of Gold Ore Processing, 2e (2016, Elsevier). Dr. Adams is widely published in metallurgy and chemistry, including some 50 papers on gold processing. He has made a significant contribution to the chemistry and optimization of the carbon-in-pulp process for gold recovery, for which he received the Raikes Gold Medal from the South African Chemical Institute and two silver medals from the South African Institute of Mining and Metallurgy. Notable contributions have included project management and metallurgy of integrated pilot-plant campaigns for definitive feasibility studies on the processing of nickel laterites and sulfides, PGM concentrates, gold ores, and zirconiumeniobiume rare earth element ores. Currently director of Fugue Pte Ltd., Mike has been assisting from the early stages with the development of the Kell Process, a hydrometallurgical alternative to smelting, which is his current focus.