Mine Impacted Water: A resource for the circular economy in South - PowerPoint PPT Presentation

Mine Impacted Water: A resource for the circular economy in South African Mining communities Dheepak Maharajh; Tamsyn Grewar; John Neal and Michelle van Rooyen Water-Energy-Food Nexus: towards efficient national planning on 23-24 October at Amanzingwe Lodge & Conference Centre, Broederstroom, Hartbeespoort

INTRODUCTION • SA water scarce • ~ 460mm vs ~850 global avg • Considered water stressed • Mining sector water use ~ 3 to 5% • Agriculture - ~ 50 to 70% • Bad water use behaviour • Use 60% more per person • Mine impacted Water • Negative environmental impact • Ground water contamination 2

MINING SECTOR NOT HELPING!!! 3

HUMAN FACTORS Poor Water use behaviour Water Inefficient Mining waste water sector scarcity treatment pollution Agriculture – 70% clean water 4

CHALLENGES FACING MINING SECTOR • To reduce the utilization of key resources such as energy and water, • To reduce the environmental impacts of the operations and of waste production, 5

SOCIO-ECONOMIC IMPACT

IMPACT OF WEAKENING MINING SECTOR • Estimates 30 years mine lifespan remains • What happens after mining? • Drastic impact on poverty 7

NEED FOR MECHANISATION • Could increase to 100 year lifespan • Job cuts • Spread of poverty • Catch 22 8

CHALLENGES FACING MINING SECTOR • To reduce the utilization of key resources such as energy and water, • To reduce the environmental impacts of the operations and of waste production, • Ensure sustainable mine closure • Create new employment to make way for mechanisation. 9

HOW CAN WE HELP?

HOW CAN WE ADDRESS THESE CHALLENGES? CO2 Community Housing, Offices, Mine Buildings AMD Passive BSR >300ppm S Algal Culture Aquaculture Neutralization FOOD Food Nutrient rich waste Metal recovery MIW Biomass Animal Husbandary Oil Animal Food Waste >300ppm S SAVMIN Extraction Feed Waste Digestate Anaerobic Digestor Sewage Biodiesel Glycerol Production Concentrated Solar BIOMIN Power Nutrient rich waste Heat Storage Electricity Gas turbine Irrigation CO2 Grey Water Energy Crops Food Crops Rain Water Carbon Mineralization Transport Transport Fuels Fuels 11

MINTEK’s AVAILABLE TECHNOLOGY OFFERINGS

AMD TREATMENT: BIOLOGICAL SULPHATE REDUCTION (BSR) • Substrate (initially, at least): – 20 % cow manure – 20 % hay – 20 % wood shavings – 40 % wood chips • Operated in down-flow mode • Daily measurements of pH levels, redox potentials, electrical conductivity and sulphate concentrations • At steady-state condition, samples removed for detailed chemical analysis 13

BSR RESULTS SUMMARY Element/ Feed Column 1 Column 2 Column 3 • Detailed chemical analyses compound (mg/L) (mg/L) (mg/L) (mg/L) SO₄²⁻ 3340 140 130 90 performed on day 486 S²⁻ 9 802 360 200 NH₄⁺ 5 709 858 697 • 140 mg/L SO₄²⁻ in Column 1 Be <0.02 <0.02 <0.02 <0.02 HCO₃⁻ 106 7802 7676 7260 • 90 mg/L SO₄²⁻ in Column 3 Na 258 195 209 241 Mg 537 514 447 399 • Sulphate removal >97 % Al 4.7 3.7 3.0 2.2 Si 5.2 23 27 29 • 200 mg/L S²⁻; 2.5 mg/L Mn PO₄³⁻ <0.01 <0.01 0.1 0.1 Cl <0.01 0.35 0.34 0.34 • S²⁻ and Mn can be removed K 172 456 531 548 Ca 587 475 544 400 in oxidative polishing Cr 0.07 0.09 0.18 0.33 Mn 36 2.0 3.4 2.5 process Fe 0.49 1.16 0.95 1.56 Co 0.06 <0.02 <0.02 <0.02 • NH₄⁺, HCO₃⁻, PO₄³⁻ Ni 0.07 0.09 0.06 0.16 Cu <0.02 0.03 0.04 0.02 • Fitness for use of final Zn <0.02 0.02 0.02 0.02 As, Mo, Ag, Cd <0.02 <0.02 <0.02 <0.02 product is under evaluation Pb <0.02 0.1 <0.02 <0.02 Alkalinity 87 6395 6292 5951 – crop irrigation, algae pH level 6.93 6.97 7.20 7.23 culture 14

BSR PILOT 15

HOW CAN WE ADDRESS THESE CHALLENGES? CO2 Community Housing, Offices, Mine Buildings AMD Passive BSR >300ppm S Algal Culture Aquaculture Neutralization FOOD Food Nutrient rich waste Metal recovery MIW Biomass Animal Husbandary Oil Animal Food Waste >300ppm S SAVMIN Extraction Feed Waste Digestate Anaerobic Digestor Sewage Biodiesel Glycerol Production Concentrated Solar BIOMIN Power Nutrient rich waste Heat Storage Electricity Gas turbine Irrigation CO2 Grey Water Energy Crops Food Crops Rain Water Carbon Mineralization Transport Transport Fuels Fuels 16

SAVMIN TM • Patented in 1998 • Evolved over the last 20 years • Latest improvements with Veolia 17

SAVMIN TM DEMONSTRATION – SULPHATE REMOVAL 250 • >92% SO 4 removal • Metals removal Cost ~ R10 – R21/m 3 – potable quality water • 18

SAVMIN TM PILOT SCALE DEMONSTRATIONS • At Stilfontein gold mine, Navigation Colliery and Grootvlei gold mine 19

HOW CAN WE ADDRESS THESE CHALLENGES? CO2 Community Housing, Offices, Mine Buildings AMD Passive BSR >300ppm S Algal Culture Aquaculture Neutralization FOOD Food Nutrient rich waste Metal recovery MIW Biomass Animal Husbandary Oil Animal Food Waste >300ppm S SAVMIN Extraction Feed Waste Digestate Anaerobic Digestor Sewage Biodiesel Glycerol Production Concentrated Solar BIOMIN Power Nutrient rich waste Heat Storage Electricity Gas turbine Irrigation CO2 Grey Water Energy Crops Food Crops Rain Water Carbon Mineralization Transport Transport Fuels Fuels 20

TECHNOLOGIES FOR INTEGRATION

ALGAE CULTURE Nutrition Algal Environment Health care Technologies Energy 22

Algae • Secondary water treatment – clean MIW • Mops up residual SO 4 , PO 4 , NO 3 , metals etc • Biomass • High in protein – animal feed • High carotenoids – high value • Lipids • Contains 20 to 70% lipids • Converted to Biodiesel • Biodiesel - ~ 70m litres/yr/mine 23

Algal culture 24

HOW CAN WE ADDRESS THESE CHALLENGES? CO2 Community Housing, Offices, Mine Buildings AMD Passive BSR >300ppm S Algal Culture Aquaculture Neutralization FOOD Food Nutrient rich waste Metal recovery MIW Biomass Animal Husbandary Oil Animal Food Waste >300ppm S SAVMIN Extraction Feed Waste Digestate Anaerobic Digestor Sewage Biodiesel Glycerol Production Concentrated Solar BIOMIN Power Nutrient rich waste Heat Storage Electricity Gas turbine Irrigation CO2 Grey Water Energy Crops Food Crops Rain Water Carbon Mineralization Transport Transport Fuels Fuels 25

AGRICULTURE • MIW – agricultural irrigation • Produce crops for food, biofuel or even mining use e.g. flotation and thickening agents • Food crops - communities • Biofuels crops – mining vehicles • Mine related products eg. Guar bean • Community job creation 26

HOW CAN WE ADDRESS THESE CHALLENGES? CO2 Community Housing, Offices, Mine Buildings AMD Passive BSR >300ppm S Algal Culture Aquaculture Neutralization FOOD Food Nutrient rich waste Metal recovery MIW Biomass Animal Husbandary Oil Animal Food Waste >300ppm S SAVMIN Extraction Feed Waste Digestate Anaerobic Digestor Sewage Biodiesel Glycerol Production Concentrated Solar BIOMIN Power Nutrient rich waste Heat Storage Electricity Gas turbine Irrigation CO2 Grey Water Energy Crops Food Crops Rain Water Carbon Mineralization Transport Transport Fuels Fuels 27

AQUACULTURE AND ANIMAL HUSBANDARY • Direct AMD use – not possible • After algal culture cleaner water • Algae protein – feed source • Fish – mess up water 28

AQUACULTURE • Ideal fertilizer or algal feed • Recycle back to algae and agriculture in flow sheet • Product sold for profit • Waste to anaerobic digestion 29

Animal husbandry • Livestock farming • Algae protein for feed • Livestock sold for profit • Manure feed for Anaerobic digester 30

HOW CAN WE ADDRESS THESE CHALLENGES? CO2 Community Housing, Offices, Mine Buildings AMD Passive BSR >300ppm S Algal Culture Aquaculture Neutralization FOOD Food Nutrient rich waste Metal recovery MIW Biomass Animal Husbandary Oil Animal Food Waste >300ppm S SAVMIN Extraction Feed Waste Digestate Anaerobic Digestor Sewage Biodiesel Glycerol Production Concentrated Solar BIOMIN Power Nutrient rich waste Heat Storage Electricity Gas turbine Irrigation CO2 Grey Water Energy Crops Food Crops Rain Water Carbon Mineralization Transport Transport Fuels Fuels 31

ANAEROBIC DIGESTION • Animal waste • Food waste • Domestic waste • Produce Biogas • Used for cooking • Electricity – community and mines 32

HOW CAN WE ADDRESS THESE CHALLENGES? CO2 Community Housing, Offices, Mine Buildings AMD Passive BSR >300ppm S Algal Culture Aquaculture Neutralization FOOD Food Nutrient rich waste Metal recovery MIW Biomass Animal Husbandary Oil Animal Food Waste >300ppm S SAVMIN Extraction Feed Waste Digestate Anaerobic Digestor Sewage Biodiesel Glycerol Production Concentrated Solar BIOMIN Power Nutrient rich waste Heat Storage Electricity Gas turbine Irrigation CO2 Grey Water Energy Crops Food Crops Rain Water Carbon Mineralization Transport Transport Fuels Fuels 33

CONCENTRATED SOLAR POWER • Power generation – supply communities • Smelter operations • Desalination of MIW 34