DELPRAT LECTURE AusIMM

Transcription

1 DELPRAT LECTURE AusIMM 2017 WATER-FACTS, PERCEPTIONS AND CONFLICTS Robert Dunne

2 WORLD WATER DEMAND DRIVERS Population Growth Economic Growth Considerable demand in the next decades Water supplies will remain relatively constant Many countries will be severely short of water by

3 MAJOR EARTH SURFACE WATER RESEVOIRS (based on Gleick, 1996) Oceans/Seas 96.5% Icebergs/Glaciers 1.74% Groundwater 1.69% Ground Ice/Permafrost.022% Lakes.013% Atmospheric.001% Swamp.0008% Rivers.0002% 3

4 WATER CYCLE

5 World Water Usage Agriculture ~ 66% Industry + ~ 23% Households ~ 7% + Mining ~ 3% 00/00/00 Place title of presentation here 5

6 AUSTRALIA WATER USAGE Sector % Agriculture, forestry and fishing support services 61.0 Total mining 4.4 Total manufacturing 3.4 Electricity and gas supply 1.8 Water supply, sewerage and drainage services 12.5 Waste collection, treatment and disposal services 0.0 Other industries 6.3 Final consumption by households 10.7 Total 100

7 WATER CONSUMPTION BY STATE Sector NSW Vic. Qld SA WA Tas. NT ACT Aust. GL GL GL GL GL GL GL GL GL Agriculture 4,120 2,738 2, ,410 Aquaculture, forestry and fishing Mining Manufacturing Electricity and gas supply Water supply, sewerage and drainage services ,166 Other industries ,089 Intermediate consumption by all industries ,848 3, , ,522 Final consumption by households ,852 Total water consumption 6,329 4,215 3,748 1,031 1, ,375

8 Water Availability Rainfall and Water Storage Ground Water Lakes 00/00/00 Place title of presentation here 8

9 Water Availability Waste Water Aquifer Storage 00/00/00 Place title of presentation here 9

10 Water Availability- Surface Water Surface water can fluctuate markedly 80% of rainfall water used for agriculture 00/00/00 Place title of presentation here 10

11 Water Availability Surface Water Storage Water Resource Management over last century relied on reservoirs/dams and canals to distribute water Large evaporation losses and very expensive to build new facilities Changing weather patterns problems for current storage facilities 00/00/00 Place title of presentation here 11

12 Water Availability- Surface Water Two Thirds of Cities Rely On Surface Water Supply 00/00/00 Place title of presentation here 12

13 Water Availability- Surface Water Transporting Fresh Water Transporting fresh water over long distances is on the increase Australia: Perth- Kalgoorlie pipeline 560 km, longest in the world till around the late 1980 s Libya: 1227 km long pipeline from large aquifer to Tripoli capable of transporting 20 million cubic metres of water per day (1990) China- combination of pipelines and aqueducts completed in 2014 transports water over 1500 km from the Yangtze river to Beijing. Some 40 BM3 per year. 00/00/00 Place title of presentation here 13

14 Water Availability-Groundwater Most readily available freshwater resources are from large aquifers Slow rates of natural depletion 00/00/00 Place title of presentation here 14

15 Water Availability-Groundwater External withdrawal has increased such that in many instances they exceed natural replenishment Can create unintended impacts on surface water Rural communities mostly use groundwater 00/00/00 Place title of presentation here 15

16 Water Availability-Lakes Also large source or freshwater Quality water for industrial use Problem of 217 lakes survey world wide» 54% in Asia are eutrophic (oxygen depleted by nutrients)» 51% in South America are eutrophic» 28% in Africa are eutrophic Greatest problem where there is a large population and scarce financial resources 00/00/00 Place title of presentation here 16

17 Water Availability Waste Water Treatment and Recycling Large cities treating waste water and recycling Examples Orange County Water District-California Large quantity treated by RO and other process (ph modification, precipitation etc) Treated water recharged into local aquifers 00/00/00 17

18 Aquifer Storage and Recovery (ASR) Edwards Aquifer Water in sand aquifers tends to stay in place or move slowly Store water in sand and return years later and extracted No evaporation compared to reservoir Injected water needs to meet drinking water standard 00/00/00 Place title of presentation here 18

19 FRESH WATER FROM SEA WATER OPTIONS Thermal Distillation Water is heated; creating a vapor that is condensed to form fresh water. Thermal processes are traditionally high-energy Reverse Osmosis The RO membrane separation process separates freshwater from saltwater under high pressure. RO is relatively new as compared to the first commercial unit was installed in the Florida Keys in 1971.

20 Desalination Plants Worldwide Estimates vary widely between 15,000 20,000 desalination plants worldwide. Micro desalination plants operate near almost every natural gas or fracking facility in the United States

21 LARGEST DESALINATION PLANT At Ras Alkhair in Saudi Arabia. Built 2014, supplies1 million cubic meters of drinking water per day Uses 2400 MW of power for the desalination processes. Consists of 8 evaporators and 17 reverse osmosis units. Estimated average water consumption for those connected to the network is about 235 liters per capita per day.

22 LARGEST DESALINATION PLANT

23 AUSTRALIAN CITY DESALINATION PLANTS Location Built Capacity % Water Supply ML/day Perth % of Perth % 0f Perth Gold Coast % SE Queensland Melbourne % 0f Melbourne Sydney % of Sydney Adelaide % of Adelaide

24 DESALINATION Water production costs are in general between $0.7 and $1.40 per m3, for desalination plants Combinations with heat only plants result in considerably higher ($ per m3) water production costs. When water storage, transport and distribution costs are added and losses included, the final cost of water (to the consumer) is significantly higher.

25 WATER REQUIREMENTS FOR COAL POWERED To generate 1 MW/hr of energy require L of water 2600 L of water consumed, or 62,000 L per day (62 cubic metres) water requirement for 270 people

26 WATER QUALITY Deterioration can be due to: 1. Natural (Geogenic) Conditions Water rock gas interactions Soil gases and organic decay CO 2 and acid generation Problems are arsenic and fluoride in water 2. Man Made (Anthropogenic) Rainwater adsorbs sulfate, ammonia, nitrate and carbon dioxide Industrial chemicals, oils and greases from roads and city parking areas Chemical plants, landfills, agriculture and mining 26

27 WATER QUALITY CHANGES TO SEA WATER Man Made (Anthropogenic): Rivers Carry Phosphorus, Nitrogen, Calcium, and Suspended Solids Some 7600B tons/year into the ocean

28 WATER IN THE MINING INDUSTRY 00/00/00 Place title of presentation here 28

29 WATER IN THE MINING INDUSTRY Many mines located in remote areas with limited access to high quality water The source and quality varies from mine site to mine site Mining impacts on water quality and quantity most contentious of mining development issues Competition with rural freshwater and agricultural supply 00/00/00 Place title of presentation here 29

30 TRUST IN THE INDUSRTY SECTORS

31 CONFLICT BY COMMODITY

32 CONFLICT CAUSES IN MINING

33 MINING WATER USAGE Dust Control Separation processes and leaching Smelting and refining Power Station Drinking /Domestic Water 33

34 WATER RESOURCES FOR MINING (based on Kaufmann and Nadler 1969) 00/00/00 Place title of presentation here 34

35 WATER MANAGEMENT Many gold mines are situated in remote and arid areas where water is scarce and water available for mine use tends to be saline Focus therefore is to reduce water consumption wherever possible

36 ALTERNATIVE WATER SOURCE HYPER SALINE AND SEA WATER Hyper-saline ground water (+100,000ppm tds) Western Australia Gold and nickel flotation Gold leaching Sea Water application Texada Mill, Canada (1970 s) Iron ore and Cu flotation Black Angel Pb-Zn Mine, Greenland ( ) Batu Hijau Copper Mine, Indonesia Cu flotation (1990s) Michilla Copper Mine, Chile 1990 s (Cu heap leach) Esperanza Copper, Chile 2010 Cu-Mo flotation

37 METALLURGICAL IMPACTS OF USING SALINE WATER Advantages No competition with other users Large water resource Possible flotation benefits Disadvantages Corrosion of equipment Magnesium content (ph buffering- large amounts of lime required) Less flotation selectivity (copper/pyrite) Lower Mo recovery (Cu/Mo separation)

38 MINING DESALINATION AND METAL REMOVAL USING RO Potable water used on many mine sites Large Process Water Application Examples Date Capacity Yanacocha ML/day Candelaria ML/day CITIC Iron Ore ML/day Escondida ML/day

39 MINING RO PROCESSING STREAMS

40 SEWAGE WATER ALTERNATIVE PGM Mines, South Africa Cerro Verde Copper Mine 2013 Cadia Gold Mine Australia Queensland Alumina-Australia Fosterville Gold Mine 40

41 CERRO VERDE COPPER MINE The Cerro Verde copper mine is in a desert environment approximately 30 km southwest of Arequipa. Rainfall averages 3.7 cm per year Expansion project, to triple throughput from 120,000 tpd to 360,000 tpd Water source was local river contaminated by sewage from the city of Arequipa, close to one million inhabitants Cerro Verde build a US$550 million waste water treatment plant in exchange for 1m3/second (87ML/day) of treated water for copper concentrator

42 ARAKIPA SEWAGE TREATMENT PLANT

43 RIVER BEFORE AND AFTER INSTALLATION OF SEWAGE TREATMENT PLANT

44 MINE SITE WATER BALANCE Mine Sites With Positive Water Balance High rainfall situation, discharge requirements provided by in-country EPA Mine Sites With Negative Water Balance Arid regions, issue is source of make up water (rain, river, ground water), focus is water storage, water recovery and minimizing water usage

45 WATER CONSUMPTION AUSTRALIAN MINING SECTOR Mining ML % Coal mining 128, Oil and gas extraction 45, Metal ore mining 480, Non-metallic mineral mining and quarrying 52, Exploration and other mining support service 60, Total mining 768,

46 MINE SITE WATER BALANCE DEWATERING AND RECYCLING Thickening Tailing Facility Evaporation Losses Seepage Losses Filtration/ Dry Stacking 46

47 REASONS FOR MINIMISING WATER CONSUMPTION Lower demand for external water Environmentally desirable practice Positive social implications Lower operating costs Residual reagents recycled 47

48 WATER REQUIREMENTS FOR PROCESSING Process % solids W/S ratio t water/ t ore Grind/Classification Flotation Leaching Thickening

49 DEWATERING SYSTEMS AND WATER CONSUMPTIONS % Solids t water / t ore Hi Rate Thickening Paste Thickening Filtration Heap Leach 0.10

50 WATER LOSSES IN TAILING STORAGE FACILITY % Evaporation Losses 5-60 Water entrainment (pore space) Water Seepage 5 Heap Leach Evaporation 5-10

51 EVAPORATION Methods to reduce: Structurally- such as wind breaks, covers and dam design Floating balls Floating covers Chemical mono layers Shade structures

52 WATER RECYCLING ON PROCESS PLANTS Copper Cliff Mines (1941) 50-70% Arizona (1970 s) 69-73% Large mines (2008) 55 to 70% Cadia Mine (NSW ) 80 %

53 DRY STACKING- FILTERED TAILINGS Arid regions Water conservation is crucial Metal recovery from solution is enhanced High seismic area precludes conventional impoundments Cold regions-water handling difficult in winter Topography excludes conventional construction Materials of construction scarce or extremely expensive

54 DRY STACKED TAILINGS Eliminates problems and risk with conventional TSF design Over 60 operations using dry stacked tailing Additional advantages for gold and silver Increase gold/silver recovery from solution Reduced cyanide consumption due to recycle No cyanide destruction

55 FILTRATION AND DRY STACKED TAILINGS La Coipa Gold Mine Chile

56 DITCHES FOR DRY STACKED TAILINGS Normal tailings storage/management facilities only require a 100 year interception ditch A dry stack facility is similar to a waste dump but not simply rock. The dry stack material has the possibility of being suspended in a flood situation. There are no spillway or embankment wall so the particles could be carried downstream and impact the surrounding environment. As such, some countries such as Chile have imposed that the cut-off (or interception) ditches be sized for the 1:10,000 year storm or PMF, which ever is greater.

57 Water Recycle-Impacts QUANTITY AND QUALITY MAGNITUDE OF CHANGE

58 WATER RECYCLE IMPACTS Decomposition of reagents may impact differential flotation (complex ore treatment) Dissolved and suspended solids that will impact on gland water, sprays and service water Mixing streams with different phs and Ehs can lead to precipitates that could impact flotation recovery and grade

59 WATER RECYCLE IMPACTS Microbial activity have surface active properties that impact flotation and froth phase Seasonal temperature changes will lead to oxidation of sulfides, ph and Eh changes Seasonal rainfall result in changes in salinity (flotation, leaching)

60 WATER CATEGORY STANDARD WATER INPUT AND OUTPUT Based on the Minerals Council of Australia Water Accounting Framework Provide information on all sources of water used at a mine site (quantity and quality) Provide information on the quantity and quality of water released or sold to a third party from a mine site Water quality divided into three category Category 1: Close to drinking standard (disinfection) Category 2: For agriculture and recreation Category 3: Saline water that cannot be used for agriculture

61 WATER CATEGORY REPORTING FOR LARGE MININING COMPANIES Mining Company Withdrawl Recycle Surface Sea Ground Rain ML % ML ML ML ML/% Glencore Alcoa AngloAmerican 240 saved % 9% Barrick Gold BHP 11% 34% 46% Freeport % 6% 4% Fortescue 177 Goldfields Codelco 170 lower Rio Tinto South Teck

62 WATER TREATMENT TECHNOLOGIES (WATER DISPOSAL, AMD AND OTHER)

63 MEMBRANE SYSTEMS

64 MEMBRANE SYSTEMS

65 NANOFILTRATION Nanofiltration was developed primarily for drinking water applications. Becoming quite popular for irrigation use. Emerging as an environmentally friendly alternative to traditional water softener systems for removing hardness from water.

66 COMPARISON NANOFILTRATION AND REVERSE OSMOSIS Pressure (Bar) Cost /M3 Reverse Osmosis $0.70-$1.40 Nanofiltration $0.30-$0.70

67 COMPARISON OF WATER RESOURCES WATER SOURCE HUMAN NEEDS MINES RAINWATER/STORAGE Major Minor GROUNDWATER Major Major LAKES Minor? SEWAGE Minor Virtually none RO WATER Reasonable Small SEAWATER None Minor, increasing

68 CONCLUSIONS Tensions will continue to increase between agriculture, urban development and industry (mining) for fresh water. Politically mining will be forced to use alternative water resources Ever increasing requirements to improve discharge water quality and dispose of heavy metals from water treatment Increasing focus to reduce water losses and so increase water recycle

69 THANK YOU 00/00/00 Place title of presentation here 69