HOW ARE MINERAL SANDS MINED ON NORTH STRADBROKE ISLAND?

1. HOW ARE MINERAL SANDS MINED ON NORTH STRADBROKE ISLAND?

2. INSTRUCTIONS FOR VIEWING THIS PRESENTATION Click through the slides to view this presentation. Follow the links in grey to view more information on the different steps involved in the mining of mineral sands.

3. THE SAND MINING PROCESS Click on each image for information about each stage of the sand mining process

4. FINDING THE MINERAL EXPLORATION DRILLING The aim is to identify where the minerals are in economically viable quantities. Initially the area is drilled on a 100m x 200m grid (probable resource). If sufficient mineral is found a more detailed drilling program is conducted to upgrade to a proven resource status. Sample holes are drilled on a 50 x 100m grid across area. Drill holes are taken down to basement clay/rock (up to 250m). Samples are taken on 3m interval for total heavy mineral volume. Mineral samples taken and delivered to the North Stradbroke Island laboratory

5. THE SAND MINING PROCESS Click on each image for information about each stage of the sand mining process

6. FINDING THE MINERAL LABORATORY ANALYSIS Samples are analysed by the laboratory on North Stradbroke Island. The data is used for ore-body modelling to identify the path of the mine, which maximises mineral production. This initial mine path is then adjusted taking into account the further information gathered. Laboratory analysis is also utilised at the end of the mining process to ensure the quality of the mineral sands before they are transported to Pinkenba. OVERVIEW laboratory analysis

7. FINDING THE MINERAL DETAILS ON LABORATORY ANALYSIS The 300gram sample is split into 100g lots for analyses Sample washing removes fines (clay particles called slimes)

8. FINDING THE MINERAL LABORATORY ANALYSIS Drying to remove water (samples must be in dry weight) Lithium Silico Tungstates (LST) separation. Separates the heavy mineral fraction from the lighter sand using the LST solution.

9. FINDING THE MINERAL LABORATORY ANALYSIS LST continues (fluid and sand mix added to the funnel) Releasing LST mixture with heavy mineral contained

10. FINDING THE MINERAL LABORATORY ANALYSIS Removing LST from sand (LST is reused)

11. FINDING THE MINERAL LABORATORY ANALYSIS Removing LST from sand continuing (LST is reused)

12. FINDING THE MINERAL LABORATORY ANALYSIS Dry material now devoid of LST, ready for analysis.

13. THE SAND MINING PROCESS Click on each image for information about each stage of the sand mining process

14. PRE-MINE STUDIES PREPARING FOR MINING Before mining can commence various surveys are conducted to provide information for planning, monitoring, environmental management and rehabilitation. Pre mine feasibility studies look into the economic parameters of the various proposed operating methods and mine paths to determine which would be the most profitable method of extraction given environmental and socio-economic considerations. This study is usually done in parallel with the environmental studies as they feed into each other. Pre-mine survey undertaken at Yarraman in 1996. MORE INFORMATION environmental and pre-mine studies

15. ENVIRONMENTAL STUDIES PREPARING FOR MINING These studies provide pre-mine baseline studies of key environmental aspects of the operation and assess potential impact on the existing environment. Data collected in an environmental survey include:• Existing topography• Vegetation studies• Fauna studies to determine the character, composition and diversity of terrestrial, vertebrae and invertebrate fauna.• Soil studies to identify depth, type, nutrient status and volume of soils present.• Hydrological data This baseline data is necessary for planning, monitoring, environmental management and rehabilitation requirements to minimise future environmental impacts. Click on the box above to view a video clip on Environmental Studies and Pre-Mine Planning

16. THE SAND MINING PROCESS Click on each image for information about each stage of the sand mining process

17. PLANNING PREPARING FOR MINING Project planning is the detailed planning phase and involves the development of the Life of Mine Plan and inclusion of the new project in the Plan of Operations. This would include setting the final mine path, developing clearing and stripping schedules, infrastructure planning and location, planning for water supply requirements and finalising tailing placement and landform reconstruction plans and rehabilitation schedules. Community consultation is also undertaken with community groups in the mine planning phase. These studies also include a socio-economic component.

18. THE SAND MINING PROCESS Click on each image for information about each stage of the sand mining process

19. CLEARING AND TOPSOIL STRIPPING PREPARING FOR MINING Prior to mining bulldozers are used to clear the vegetation ahead of the mine face. The vegetation is stockpiled then used in post-mining rehabilitation or burned. The topsoil is also removed from the mine path and stockpiled for use in the rehabilitation process. Click on the image above to view a video clip on Clearing and Topsoil Stripping

20. THE SAND MINING PROCESS Click on each image for information about each stage of the sand mining process

21. DREDGE MINING MINING Mining is by dredge floating on an artificial freshwater pond. This method allows large volumes of sand in a slurry form to be pumped to the plant in a cost efficient manner. This is necessary because the minerals CRL mines comprise less than 1% of the sand mass. The mines each process around 3 500 tonnes of sand an hour. The dredge constantly extracts material from the front of the pond, while reject material is being placed at the rear. This allows the mining operation to move through the landscape at approximately 1km per year. A dredge and concentrator at Enterprise Mine

22. THE MINING PROCESS MINING Click on the box below to view a video clip that outlines the Dredge Mining Process.

23. DREDGE MINING MINING Click on each step below for detailed information on the dredge mining processes Direction of travel 3. Concentrator 1. Dredge 2. Water Management and Dredge Mining

24. THE DREDGE MINING As the dredge mines, the face is undermined and will slowly collapse into the water to be processed. The dredge is fitted with a water canon, which fires a high-pressure jet of water to break up any material, which remains in chunks in the face. The spud is used to anchor the dredge at a fixed pivot point, allowing the cutter head to make sweeps across the mine face. An auxiliary spud is carried at the back of the dredge in case the working spud should break. Spuds are around 19 metres long and 70cm in diameter. CROSS SECTION the dredge A dredge at Enterprise Mine

25. CROSS SECTION OF THE DREDGE MINING MORE INFORMATION the cutter

26. THE ROTATING CUTTER MINING At the front of the dredge a submerged rotating cutter operates 12-15 metres below the surface of the pond. It loosens the sand and extracts the minerals, which is pumped through pipe lines to the concentrator at a rate of approximately 3 000 tonnes per hour. DREDGE MINING DIAGRAM A diagram of the Rotating Cutter. A picture of the Rotating Cutter.

27. WATER MANAGEMENT AND DREDGE MINING MINING Water management bores and spears are installed alongside the mine path for groundwater management. This allows CRL to prevent negative impacts such as inundation of low lying areas as well as enabling some water passing through the base of the pond to be reused. The water level in the dredge pond is maintained where necessary by pumping water from fresh water swamps on the island. Click on the image above to view a video clip on water management during Dredge Mining. DREDGE MINING DIAGRAM

28. THE CONCENTRATOR MINING The concentrator cleans the sand and seperates the minerals from the bulk of the sand tailings, which is known as quartz. It then begins the separation process of the sand minerals into zircon and an ilmenite and rutile mix. Two main processes are used including spiral separation and Wet High Intensity Magnetic Separators (WHIMS). FLOW CHART the concentrator The Concentrator

29. FLOW CHART OF THE CONCENTRATOR MINING Click on each step below for detailed information on the Concentrator processes. MINERAL CONCENTRATING PLANT (FLOATING) 4 3 1 2

30. THE TROMMEL MINING The dredge feeds directly in to the trommel. The trommel is a large rotating drum, which contains mesh screens to remove debris such as roots and rock-like material from coming from the dredge. Inside the Trommel The Trommel Screen FLOW CHART the concentrator Replacement screens for the Trommel

31. THE SURGE BIN MINING The cleaned slurry from the trommel is pumped to the surge bin before being passed to the rougher mill. The surge bin allows the fluctuations in head feed from dredge to be offset, so that material can be fed to the spirals at a constant rate. The slurry contains about 1% heavy minerals and 99% silica (reject sand). Clean Slurry travelling to the surge bin. FLOW CHART the concentrator

32. THE SPIRAL CIRCUIT MINING The Spiral Circuit is made up of two sections, the Rougher Mill and the Cleaner Mill. Both sections extract heavy minerals from sand slurry. In the concentrator, a gravity separation process using a series of water fed spirals extracts the heavy mineral sands comprising rutile, zircon and ilmenite. MORE INFORMATIONspiral circuit The Spiral Circuit inside the Concentrator

33. MINING As the sand flows down the water-fed fibreglass spirals, heavy mineral collects on the inside and lighter minerals are swept to the outside. The rougher mill contains over 1200 spirals to separate the heavy minerals from the residue sand. The cleaner mill contains a further 172 spirals which process the concentrate to 98% mineral. Cross Section of the Spiral Photograph showing a close-up of the spiral. If you look closely you can see the darker minerals forming on the inside of the spiral. FLOW CHART the concentrator

34. WET HIGH INTENSITY MAGNETIC SEPARATORS (WHIMS) MINING After gravity separation, the heavy mineral concentrate is pumped across wet high intensity magnets (WHIMS). The magnetic separator extracts the Ilmenite, which is magnetic, from the Rutile and Zircon, which are not. The separate mineral concentrates are pumped through pipelines to stockpiles at the edge of the mine site. CROSS SECTIONthe WHIMS Photograph of one of the WHIMS

35. CROSS SECTION OF THE WHIMS MINING

36. MINING As the dredge pond advances, the residue sand containing mostly quartz is pumped behind the concentrator into the previously mined dredge path. Information collected in pre-mine surveys is used to reconstruct landforms similar to the pre-mining landforms. These images show the existing mine path, once the dredge has been through.

37. ON-SITE STOCKPILE MINING ON-SITE CONCENTRATE STOCKPILE AREA The separate mineral concentrates are pumped through pipelines to stockpiles at the edge of the mine site. Click on the diagram above for more information about On-Site Stockpiles

38. ON-SITE STOCKPILE MINING Stockpiles of the separated minerals are formed from the pipes. Illmenite and Rutile Loaders are used to fill trucks (25 tonne capacity) with concentrate from stockpiles,for transport to a loading facility in Dunwich. Zircon

39. THE SAND MINING PROCESS Click on each image for information about each stage of the sand mining process

40. REHABILITATE MINE SITE AFTER MINING CRL restores, on average, 75 hectares of their leases on North Stradbroke Island each year and have progressively rehabilitated more than 4 000 hectares of land since 1966. There are 3 main stages in the Rehabilitation Process.

41. THE SAND MINING PROCESS Click on each image for information about each stage of the sand mining process

42. TRANSPORT MINERAL PROCESSING THE LOADING FACILITY AT DUNWICH ON NORTH STRADBROKE ISLAND Every week CRL transports, on average, five 1,800-tonne loads of mineral concentrates by barge from North Stradbroke Island to the dry mill located at Pinkenba, near the mouth of the Brisbane River, for final separation. Travelling from NSI across Moreton Bay to Brisbane takes four hours. DUNWICH CONCENTRATED LOADING FACILITY

43. THE SAND MINING PROCESS Click on each image for information about each stage of the sand mining process

44. MINERAL PROCESSING PROCESSING CRL has a dry mill at Pinkenba near the Gateway Bridge to further separate the heavy minerals. A crane and bucket is used to pick up the mineral and to feed the dry mill. Minerals are unloaded for further processing at CRL’s Pinkenba Plant OVERVIEW final mineral separation process at Pinkenba Click on the map above for a better view of Google maps

45. FINAL MINERAL SEPARATION PROCESS AT PINKENBA PROCESSING Click on each of the processes to find out more about the Mineral Separation at Pinkenba

46. SPIRAL CONCENTRATOR AND WET TABLES PROCESSING In the Dry Mill the mineral concentrates are again passed over spirals to remove residual sand and then over 'wet tables' to discard quartz and light heavy minerals. Fine particles are removed in the wet concentration steps and pumped to a small dam. Water from this dam is recycled when the fines have settled. In the Dry Mill, concentrates are dried in a kiln and electrostatically separated into conductors (rutile and some residue ilmenite) and non-conductors (zircon). FLOW CHART mineral separation process

47. ZIRCON WET PLANT PROCESSING Non-conductors from the rutile separation plant are sent down a bank of ten spirals and eight wet tables to separate more middlings material. Wet tables provide another means of using gravity to discard quartz and light heavy minerals(middlings). Fine particles are removed in the wet concentration steps and pumped to a small dam. FLOW CHART mineral separation process

48. ZIRCON SEPARATION PLANT PROCESSING The kiln dried zircon wet plant product is separated using electrostatic separation, followed by magnetic separation. The final traces of conductors are cleaned from the zircon using high tension roll separators and induced roll magnets. FLOW CHART mineral separation process

49. HIGH TENSION ROLL SEPARATORS PROCESSING High-tension roll separators are used to perform electrostatic separation of conductors and non-conductors. Mineral sands are fed at predetermined rates near the top of an earthed rotating roll and carried into the field of influence of a charged ionising electrode. All particles acquire a charge from the field. As the mineral grains move out of the field of influence, the conductor grains lose their charge to the earthed roll and are thrown from the roll surface by centrifugal force. The non-conducting grains adhere to the rotating roll and pass an AC wiping electrode, which negates their charge and the grains begin to drop off the roll. This discharge is completed by a tensioned brush. FLOW CHART mineral separation process

50. RUTILE SEPARATION PLANT PROCESSING Mineral concentrates are dried in a kiln and electrostatically separated into conductors (rutile and ilmenite) and non-conductors (zircon). The rutile is cleaned electrostatically, then passed over magnets to remove ilmenite and other magnetic minerals. Non-conductors are fed to the zircon wet plant. FLOW CHART mineral separation process