Pwc Basics of Mining 6 Som a Future of Mining

8/14/2019 Pwc Basics of Mining 6 Som a Future of Mining

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2 0 12 A m er i ca s Sch o o l o fM i n e s

W Scott DunbarUniversity of British Columbia

www.pwc.com

Basics of Mining and Mineral Processing


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A g e n d a

Geological Concepts

Mining Methods

Mineral Processing Methods

Mine Waste Management

Mining and Money

A Future of Mining


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A F u t u r e o f M i n i n g : T h e To p i cs

Drivers of innovation in

mining

Automation, rapid excavation

In situ and underground processing

Some different concepts

A Future of Mining 3


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Su st a i n a b l e M i n i n g a n d M i n er a l P r o cessi n g

Energy use

Social Impact

Waste disposal

Resource depletion

Can all this be done without jeopardizing the ability of future generations to meet their needs?

Or the ability of the industry to continue operating?

Environmental Impact

Mining and Mineral Processing



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T h e ca l l o f t h e r eser v es t r en d t o

u n d e r g r o u n d

0 500 1000 1500 2000 2500 3000 35000.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

1.8

2.0

2.2

2.42.6

2.8

3.0

3.2

GrasbergNorthparkes

Palabora

Andina

El Teniente

Codelco Norte

Highland Valley

Antamina

Minto

BagdadCerro VerdeBingham CanyonMorenci

Resolution

Galore Creek

Oyu Tolgoi

New Afton

Fungurume

Legend Proven + Probable Reserves Measured + Indicated Resources

A v e r a g e

C o p p e r

G r a

d e

( % )

Reserves or Resources (Mt)

All near end

of mine life

No sign of these kinds of deposits (yet)

Most large new copper mines are

underground mines



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N o t es: T h e ca l l o f t h e r eser v es To obtain reserves mining companies must take on some significant unsystematic risks (risks notrelated to market changes) associated with exploration, project feasibility and constructability of newprojects in places where there is little geological knowledge or infrastructure. One way to diversify

these risks and still attract investment is to have a steady flow of cash from existing operations, someof which can be used to provide opportunities for development of new projects. If the unsystematicrisks cause the new projects to fail, the existing operations provide a safety net.

The large grades and/or resources of some copper deposits shown here attract large miningcompanies, but there are significant unsystematic risks:

Freeport McMoran: Fungurume in the Congo. Political risks as well as social and health issuesRio Tinto, Ivanhoe Mines: Oyu Tolgoi in Mongolia. No infrastructure and uncertainty about whatroyalties the Mongolian government will charge

Rio Tinto: Resolution project east of Phoenix. Orebody at a depth of 2 km in rock where thetemperatures are 80 C. Feasibility of any mining method under these conditions is uncertain.

Teck Cominco, Novagold: Galore Creek in northwestern BC. No roads, no power and significant watermanagement issues at the proposed mine.



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M I N E CO s b a l a n ce sh eet


1.85%4.42%

70.5%

7%

9.47%

6.8%

Cash Receivables Inventories

PP & E Investments Other

Property, plant and equipment

This is the average from the annual reports of five mining companies in 2005. Mining companies have a lotof their balance sheet tied up in physical assets. This affects return on equity and return on invested capital.


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Cr ea t i n g v a l u e

Revenues CostsReturn on Equity

Assets

Usual approach to increase RoEis to reduce operating costs



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M i n e A u t o m a t i o n

Why? To reduce costs. Also safer

Possible, in principle, to automate any part of the mine cycle more efficient use of assets and labor

Tele operation:

tele operated LHDs, three drills, one operator above ground some success at Vale (formerly INCO) mines in Sudbury, Ontario

Autonomous trucks and shovels:

BHP and

Rio

Tinto

for application to coal and iron ore mines



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There have been some significant advances in mine automation over the last decade. Forexample, Komatsu has provided autonomous 290 tonne haul trucks (930E 4AT) to bothCodelco in Chile and Rio Tinto in Australia. Caterpillar is also working on developing an

autonomous 700 tonne (!) truck.Deep underground mines have a strong incentive to be involved in mine automationbecause of long travel times of workers to and from work areas and the difficult, possiblyunsafe, work conditions at large depths.

N o t es: M i n e A u t o m a t i o n t o r ed u ce co st s



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T h i s L H D h a s n o d r i v er


Light rope guidance system

www.canadianminingjournal.com


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N o t es: T h i s L H D h a s n o d r i v er

In some cases, tele operation can be slower than directly operated machines. However, it isreliable and that is very important in a mining operation which depends on a regular feed

of material.One Canadian prime minister (Jean Chretien) was shown operating a LHD in a mine inSudbury, Ontario from a conference hall in Toronto. So if a politician can do it, there is noend to the possibilities.



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A u t o n o m o u s t r u ck s ( a n d sh o v el s o n e d a y )

Source: www.komatsu.com/CompanyInfo/press/2008122516111923820.html

Rio Tintos West Angeles

iron mine, Australia



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R a p i d ex ca v a t i o n f o r r a p i d d ev el o p m en t

Roadheader Roadheader cycleNo drilling and blasting



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N o t es: R a p i d ex ca v a t i o n f o r r a p i d d ev el o p m en t

Most of these technologies have been applied to tunnel construction but have not yetbeen applied in mining construction or development.

Other technologies such as water jets and projectiles have been tested as a means of rapidexcavation.



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D o es co st cu t t i n g r ea l l y w o r k ?

1 9 9 0

1 9 9 1

1 9 9 2

1 9 9 3

1 9 9 4

1 9 9 5

1 9 9 6

1 9 9 7

1 9 9 8

1 9 9 9

2 0 0 0

2 0 0 1

2 0 0 2

2 0 0 3

2 0 0 4

2 0 0 5

2 0 0 6

2 0 0 7

0

200

400

600

800

1000

1200

1400

D o w

J o n e s

T o

t a l R e t u r n

I n d e x

Basic Materials (includes mining) Consumer Services Consumer Goods Oil and Gas Financials Health Care Industrials Technology Telecommunications Utilities

Not really, if comparisons made to other industries

Also

Energy and equipment costs are significant

Dow Jones Total Return Indices



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W h a t a b o u t t h e a sset s?

Capital Operating productivityproductivity

Revenues Costs Revenues Costs OutputAssets Output Assets

With existing technology it is possible to find ways of using assetsmore efficiently or to use less of them.

Industry focus



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Pr o cess I n t eg r a t i o n m i n e t o m i l l o r m i l l t o

m i n e

Waste ore separation at face

or at pit wall

metal

Mine Mill

Concentrate to surface

Existing technologies metal

the wall

Current paradigm

The subject of a lot of research



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N o t es: Pr o cess I n t eg r a t i o n

Mine Ore type Separation method % Waste rejectedMcCreedy East, ON Narrow vein copper Optical sorting

Dense media

55.9%

McCreedy West, ON

Massive nickel sulfide Conductivity sortingDense media

21.6%

Fraser Mine, ON Narrow vein copper Dense media 44.3%

Thayer Lindsley, ON Massive/ banded nickel

sulfide

Dense media 14.2%

Some trials of pre concentration (waste ore separation) at underground mines in Ontario

Ore and waste minerals often have different optical properties (i.e., they respond to aparticular kind of light differently), different electrical conductivities, and differentdensities. Thus ore and waste minerals will reflect a particular kind of light differently. In

the presence of an electrical current, one will resist the current (typically the waste) andthe other will pass the current. If a dense medium is mixed with the ore, the lighterminerals (typically the waste minerals) will float to the top. Thus each of these differencesin properties can be used to separate the two types of minerals.



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Develop radically different technologies that can do mining andmineral processing with small (micro) assets

minimize material handlingcheap and disposable machines

W h y n o t r ed u ce a sset s?


Insitu or near situ

processingmetal

New

technologies


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B u t o n e co u l d a l so a sk :


DO WE NEED MACHINES?


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A n t s cl ea n i n g t h ei r n est



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N o t es: A n t s Cl ea n i n g t h ei r N est

1500 dead ants were put into a 10 cm diameter dish located in an artificial ant colony. Afew worker ants from the colony were released. The workers then proceeded to clean thenest by moving the dead ants into separate piles. Within 36 hours three distinct piles were

made. After 72 hours, there was one pile.

There is no foreman ant. An individual worker ant moves ants around based on cues suchas the ease with which a dead ant can be moved; if it is too hard to move, its likely in a pileso leave it alone, if its easily moved then pick it up and put it in a place where it is hard to

move which should be a pile.



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W h y n o t so r t m i n er a l s t h i s w a y ?

Construct a swarm of small machines that can detect or inferparticle size or weight

Each machine has a simple instruction set:

pick up a particle if it is heavy

drop a

particle

near

similar

particles,

or

move around to find a pile of similar particles

It is

actually

very

difficult

to

do

this

a

re

think

is

necessary.Nature might have done some of the work for us (the D of the R&D)



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M i n i n g a n d R em ed i a t i o n w i t h P l a n t s

Plant nickel accumulators

Nickel mine waste rock

Harvest, then plant native species

Phyto mining of gold mine tailings,

South Africa



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N o t es: M i n i n g a n d R em ed i a t i o n w i t h P l a n t sPlants transpire large amounts of water from the soil to facilitate photosynthesis and will accumulateany soluble metals present in soil water during transpiration. The amount of accumulation increaseswith the concentration of metals in the soil, with the ambient temperature, and with an increase inplant biomass. This can be exploited to induce hyperaccumulation of metals in the following way:

wait until the plant is fully grownwhen the ambient temperature is high, induce a high concentration of metals in the soil byapplication of a suitable chemical (thiocyanate in the case of gold or acids in the case of somebase metals)harvest the plants (which are probably dead due to the high metal concentration), burn them andrecover the metals from the ashes.

Phyto remediation is the use of plants which accumulate contaminant metals to clean mine waste.Phyto mining is the use of the plants which accumulate valuable metals to extract these metals intothe tissue mass of the plant. The process can be repeated until the metals are completely extracted.However, the concentrations of metals required to make the process economic have apparently notbeen achieved. It is an area of active research. Plant species could be genetically engineered toenhance their capabilities to absorb metals.

Source: Anderson et al, 1999. Phytomining for nickel, thallium and gold. Journal of Geochemical Exploration , 67 :407 415



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N u g g et s i n t h e d eser t

Bill Southern,

owner

of

retail

outlet in Morristown between Phoenix and Wickenburg on the

way to Bagdad minewww.nuggetshooter.com

For a video of an Aussie finding a nugget see www.youtube.com/watch?v=x5nv1lcbN54



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H o w d i d t h ey g et t h er e?

Detrital loose fragments worn away from the Mother lode But gold is relatively heavy and not that mobile

Wheres the Mother lode?

Chemical accretion crystallization from solution But gold is not that reactive (remember its a noble metal)

Wheres the water? How would it get into solution?

There must be another way.



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A n u g g et u p c l o se ( el ect r o n m i cr o sco p e)

Source: Reith et al, 2006. Biomineralization of gold: Biofilms on bacterioform gold. Scienc e, 313 : 233 236

Looks like gold encrustedbacteria white arrowsshow cell wall structureGenetic analysis of biofilms

on gold showed evidence of bacteria

(Just like they do DNA analysis on CSI)



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A n d t h e m o st p er v a si v e b a ct er i u m i s

something called Ralstonia metallidurans

Incubate R. metallidurans with gold chloride for 5 days at 30 CElectron micrograph of single microbe shows embedded gold particle

Source: Reith et al, 2006. Biomineralization of gold: Biofilms on bacterioform gold. Scienc e, 313 : 233 236


gold particle


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N o t es: A n d t h e m o st p er v a si v e b a c t er i u m i s

The genetic analysis showed that the bacteria in the biofilms on the gold nugget belongedto as many as 30 species, most of which could not be found in the soil surrounding thenugget. The most pervasive species was genetically nearly identical to the bacteriumRalstonia metallidurans , a microbe well known for its ability to precipitate some heavymetals from solution.R. mellidurans was incubated with a gold chloride (HAuCl 4) at 30 C for 5 days. The goldchloride is toxic to bacteria and so initially the bacterial count decreased. However, thebacteria count eventually increased rapidly indicating it developed a resistance to the goldchloride. The backscatter electron micrograph of the bacteria in the culture shows energypeaks corresponding to carbon, oxygen and metallic gold. The gold either accumulated inthe cell walls of the bacterium or appeared to cover the bacterium entirely.



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Su l f a t e-r ed u ci n g b a ct er i a ( SR B )


Metal sulfidesprecipitate

SRBs catalyze the reduction of sulfates

Metal sulfates are present in

contaminated water

Carbon source

SRBs exist naturally but need a carbon source to be active


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N o t es: Su l f a t e-r ed u ci n g b a ct er i a ( SR B )


SRB use carbon source and reduce sulfates in contaminated water:

Sucrose + acid + sulphate + water hydrogen sulphide + carbonic acid

C12H22O11 + 12H+ + 6SO4 2 + H2O 6H2S(aq) + 12H 2CO3(aq)

Metal ion + hydrogen sulphide metal sulphide + hydrogen ion

Me2+

+ H2S(aq) MeS(solid) + 2H+

A carbon source is not usually present SRB are dormant.

A simple carbon source: add sugar


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N o t es: Su l f a t e-r ed u ci n g b a ct er i a ( SR B )

Oxidation is an energy releasing process, and organisms make use of the energy to live. Oxygen is themost common oxidizer; it wants electrons and once it has stripped them off some helpless ion, itcombines with hydrogen to produce water. However, sulfate reducing bacteria (SRB) use sulfate as anoxidizer, reducing the sulfate to sulfide.

SRB metabolism requires an organic carbon source (as food) and some growth substrate forattachment since the bacteria cannot survive in open water. SRB metabolism causes sulfide minerals toprecipitate in marine sediments, wetlands, lake sediments, or wherever there are sources of metalions, sulfate ions and carbon. SRB are used as a method for treating acid mine drainage which containssulfates and metal ions in solution. See www.bioteq.com

The biological names of common SRBs are Desulfovibrio and Desulfotomaculum.If sucrose (sugar) is the carbon source, the chemical reactions are:

Sucrose + sulfate + acid + water sulfur dioxide + carbonic acid

C12H22O11 + 6SO42 + 12H+ + H2O 6H2S(aq) + 12H2CO3(aq)

Metal ion + sulfur dioxide metal sulfide + hydrogen ion

Me 2+ + H2S(aq) MeS(solid) + 2H+

Source: Saunders, J. A. et al. 2005. Geochemical, microbiological, and geophysical assessments of anaerobic immobilization of heavy metals, Bioremediation Journal , 9:3348



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SR B s u n d er t h e el ect r o n m i cr o sco p e


SRB biofilm

ZnS


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R em ed i a t i o n b y SR B s

See www.bioteq.com



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R eso u r ces a n d R eser v es o f M et a l s

Scrap metalScrap circuit boards

already a metal source



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N o t es: R eso u r ces a n d R eser v es o f M et a l s

Some argue that all the metal needed in the world is above ground. (no reference stilllooking for it)

On left:

Densified Scrap Metal No. 3a, Hamilton, Ontario 1997 www.edwardburtynsky.com

On right:

www.dead computers.com

Several mining companies with smelting capacity have invested in the electronics scrapbusiness. As of 1998 recycling accounts for more than half of the U.S. metal supply byweight and roughly 40 percent by value.

Sibley, S. F., 2004. Flow Studies for Recycling Metal Commodities in the United States,Circular 1196 AM US Geological Survey. Available at:

http://pubs.usgs.gov/circ/2004/1196am/



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Ca n t h e i n d u st r y g r o w i t s o w n ?

Microbes

METALS

Hot springs hydrothermal zones

supergene ore zones Electronic and metal scrap

Contaminated

water

Demonstrated at lab scale

Feasible

Not yet tried



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N o t es: Ca n t h e i n d u st r y g r o w i t s o w n ?

Three sources of metals are shown here:

Contaminated water from mines or other industrial sites

Hydrothermal waters with sulfates or supergene ore zones (e.g., Morenci mine) wherebacterial leaching is already occurring naturally

Metal and electronic scrap

The idea of recovering metals from such sources using microbes might seem crazy, but really the onlymajor barrier is our poor understanding of the interaction between metals and microbes. The amountsof valuable metals in these sources vary, but could be significant in the case of metal scrap. Metals arealready being recovered from some contaminated waters. There are obvious practical problems withdealing with a hydrothermal zone, but the temperatures are not too high. Order of magnitudeestimates of bacterial oxidation in one fracture at the Morenci mine in Arizona demonstrated that afew kg of thiobacilli could leach between 0.14 0.87 t of Cu annually. (See Enders et al, 2006. The roleof bacteria in the supergene environment of the Morenci porphyry copper deposit, Greenlee County,Arizona. Economic Geology , 101 :59 70)

Experiments have shown that bacteria and fungi grown in the presence of fine grained electronic scraplead to acid formation and leaching of metals such as copper, tin, aluminum, lead and zinc. (See BrandlH, Bosshard R, Wegmann M, 2001. Computer munching microbes: metal leaching from electronicscrap by bacteria and fungi. Hydrometallurgy , 59 :319 326.)



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I t s f u n t o t h i n k a b o u t t h i s:


22 nd century mining company

biological agents

mini machines

orebodies

metal scrap

tailings and mine waste


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N o t es: I t s f u n t o t h i n k a b o u t t h i s:


A 22nd century mining company will have swarms of small machines or biologicalagents located at orebodies, tailings ponds, waste dumps or metal scrap yardswhere it owns mineral or metal rights. These swarms would be activated to gain

access to mineralized zones or metal and carry out in situ processing to produceminerals or metal products.

The mining company would be a metal supply company that may supply metal

from ore, from waste, or by recycling, depending on demand and costs. A trulyflexible metals production system.


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M i n i n g i n 2 10 0

At a mine site in 2100 there will be

a person and a dog. Persons jobFeed the dog

Dogs jobStop the person fiddling with the

controls, valves, and pipes.

This picture is not to scale


orebody


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T H E E N D


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Pwc Basics of Mining 6 Som a Future of Mining

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