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WORKSHEET 1

ABORIGINAL USE OF RAW MATERIALS

Aboriginal people used raw materials and resources from their environment in a great many ways. Tools, Clothing, Weapons and decorations were all sourced from their local environment, or in the case of some items, traded or bartered. Ochre, iron oxide, played an important role in Aboriginal Cultures as a pigment used for decoration, artwork and ceremonies. There is evidence that red and yellow ochre were traded over distances of thousands of kilometres. Ochre from Western Australia may have been carried as far as Queensland. Stencil paintings of hands or sometimes feet were made by blowing a spray of the ground up pigment over the object. Red ochre has great significance for desert cultures that believe it is the blood of ancestral beings. It is thought to cure, protect and strengthen. Aboriginal legend tells of the death of a great kangaroo, with red ochre being his blood and yellow ochre his liver. Evidence of ochre extraction has been found in South Australian at Koonalda Cave on the Nullabor plain that dates back to between 14,000 and 24,000 years ago. Ochre mines were generally open-cut, with the mining being done by a small group who had specialized knowledge of how to correctly extract the mineral. ACTIVITY. STENCIL PAINTING Materials Disposable gloves A4 paper or cardboard Trigger action spray bottle Water-soluble red or yellow paint Or a slurry of clay if available

Directions Spread plenty of newspaper over desk or bench tops for this activity or go outside onto a grassed area. After putting on a glove, students can carefully spray a diluted quantity of paint over their outstretched hand, placed on a sheet of paper or cupboard.

From NSW Department Mineral Resources – Minfacts No 84

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WORKSHEET 2

THINKING ABOUT METALS Working in small groups, discuss each of the following questions. Make a summary of the main points of your discussion and share these with the rest of your class.

• Why didn’t all societies and cultures experience a ‘bronze age’ in their development? ……………………………………………………………………………………………………….. ……………………………………………………………………………………………………….. ……………………………………………………………………………………………………….. ………………………………………………………………………………………………………..

• How would ideas for using metals and metal working techniques have spread

from one cultural group or society to another? ……………………………………………………………………………………………………….. ……………………………………………………………………………………………………….. ……………………………………………………………………………………………………….. ………………………………………………………………………………………………………..

• What would have happened to human society if the technology of using metals

had not been developed? ……………………………………………………………………………………………………….. ……………………………………………………………………………………………………….. ……………………………………………………………………………………………………….. ………………………………………………………………………………………………………..

• Why are iron, copper, tin and lead often called ‘base metals’, while gold, silver and platinum are

referred to as precious metals? ……………………………………………………………………………………………………….. ……………………………………………………………………………………………………….. ……………………………………………………………………………………………………….. ………………………………………………………………………………………………………..

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Metal or Mineral Metal or Mineral productproduct

Mineral and chemical terminologyMineral and chemical terminology

Some UsesSome Uses

ALUMINIUM

bauxite (hydrated oxides of aluminium and iron) alumina (pure oxide of aluminium)

Beverage and food cans, buildings, furniture, electrical appliances, ships, motor vehicles, aircraft and other transport equipment, aluminium foil for packaging and kitchen use, cooking utensils, high voltage power transmission lines (with steel core).

COAL

lignite (brown coal) bituminous coal (soft black coal) anthracite (hard black coal)

Coke making for production of iron and steel and electrical power generation, coke by-products and bitumen, plastics, and heating.

COPPER

native copper chalcopyrite, chalcocite, covelite bornite (copper sulphides)

All electrical appliances, televisions, radios, telephone cables, motors for all purposes, electrical systems for vehicles, ornamental items made of brass and bronze, plumbing pipes, roofing.

DIAMONDS

chemical composition: carbon

Drill-bits abrasives, saws used in industry where hardness is needed, jewellery.

GOLD

natural gold sylvanite, calaverite (gold tellurides)

Jewellery, currency, electronic and space technology.

IRON AND STEEL

hematite, magnetite (iron oxides) limonite (hydrated iron oxide)

Household appliances, buildings, bridges, office equipment, beverage and food cans, tools, factory and farm machinery, building materials, transport equipment.

LEAD

galena (lead sulphide) cerussite (lead carbonate)

Storage batteries, petrol additives, solder for cans and containers, red lead for construction steel, type metal for printing, radiation shielding, sound proofing rooms.

MAGNESIUM

magnesite (magnesium carbonate) magnesia (magnesium oxide)

Special industrial cements, rayon making, glassmaking, fertilizers, paints, papermaking, antacid powder, lightweight car parts, rubber.

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WORKSHEET 3 CREATING NEW PRODUCTS

Many centuries ago humans discovered that alloys could be created by combining minerals. Bronze (made by combining copper and tin) was one of the earliest alloys to be developed. Other common alloys used today include brass (made from copper and zinc), and rose gold (made from gold and copper). The advantage of an alloy is that it generally has quite different, and often superior properties (eg greater strength and flexibility) to the original minerals used to manufacture it. Developments in technology over the last forty years have led to the creation of a range of ‘super’ materials-polymers (formed from chains of carbon and hydrogen molecules) and plastics. These have been made by combining two or more elements with complementary properties. The advantages of the ‘created products’ is that they have superior properties eg greater flexibility, greater strength, higher melting point, lighter weight, 1. What is an alloy? Why do you think alloys were developed?

……………………………………………………………………………………………………….. ……………………………………………………………………………………………………….. ……………………………………………………………………………………………………….. ………………………………………………………………………………………………………..

2. Name three alloys widely used in our society?

……………………………………………………………………………………………………….. ……………………………………………………………………………………………………….. ………………………………………………………………………………………………………..

3. What ‘super materials’ have been created by scientists over the last forty years? What advantages do these materials offer.

……………………………………………………………………………………………………….. ……………………………………………………………………………………………………….. ……………………………………………………………………………………………………….. ………………………………………………………………………………………………………..

4. List ten items, made of alloys or polymers

……………………………………………………………………………………………………….. ……………………………………………………………………………………………………….. ……………………………………………………………………………………………………….. ………………………………………………………………………………………………………..

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WORKSHEEET 4 FINDING THE ORE

When geoscientists are searching for mineral deposits during an exploration survey, they use their sensing devices to take measurements over the whole area they are interested in. Otherwise, they may have to come back later to fill in the gaps. This can be expensive and time wasting because it may take many hours travelling just to get back to a site.

Airborne Regional Search

Once a search area has been chosen, the geoscientists do a fast search over the area using an aircraft carrying a magnetism sensor, called a magnetometer. This senses changes in the Earth’s magnetism caused by magnetic minerals in the rocks. When they are located, these magnetic rocks will be the target areas for more detailed study. The plane flies in parallel lines, in runs 500 metres apart, to cover the whole survey area. Back in the laboratory, a computer colour codes the magnetic measurements according to their strength. This makes a coloured map of the magnetism coming up from the rocks underground. What to Do

• Colour the parts of the aero-magnetic map from the airborne survey of your exploration area, using the colour key below:

R = red (caused by highly magnetic rocks) O = orange Y = yellow G = green B = blue (caused by very weakly magnetic rocks) • Look carefully at the magnetic anomalies and choose what you think will be the best area to

prospect in more detail for useful minerals. Place a black Line around this area. (Hint: useful minerals, called ore minerals, are more likely to be found in the strongly magnetic rocks because they are sometimes injected along cracks called faults from deep inside the earth.)

• Also colour in the map of the gravity survey measurements and mark in the most

prospective gravity anomaly with a black line. (Hint: prospective rocks make gravity stronger where they are because of very heavy metals they may contain like gold, silver or lead.)

• Compare this gravity anomaly with the magnetic anomaly you chose. Are they in different

places or similar? What would you expect? ……………………………………………………………………………………………………….. ………………………………………………………………………………………………………..

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7

WORKSHEET 5 (1)

FINDING THE ORE Up the Creek for Minerals

Geoscientists also collect sediments from creek beds, making sure to mark the sampling places on a map or aerial photo. The samples (teapot-sized scoops) are tested in an assay laboratory to see what type of metals they contain, and the amounts. If there are interesting traces of minerals, then we can use the map to track down the source of the minerals. These source rocks are sometimes called the mother lode , which will have to be upstream from where the samples were taken. Part of this work has been done for your. We have a list of results from the assay lab, showing the amount of metal in creek samples which were taken from the creeks in the same area where the magnetic and gravity surveys were done. For precious metals the amount is given as parts per million, which is the same as grams per tonne – the number of grams you would get if you took all of the metal out of one tonne of rock. One gram of gold is the size of a match head not easy to find in a tonne of rock.! For other more common metals, the assays are given as a percentage, or parts per hundred. A 10% concentration would be 10 grams of metal in every 100 grams of rock.

TABLE OF ASSAY VALUES FOR CREEK SEDIMENTS Sample number

1 2 3 4 5 6 7 8 9

10 11 12 13 14 15

% copper (Cu) 1 2 7 0 2 0 3 1 1 1 3 5 4 0 7

% zinc (Zn) 2 3 7 1 3 0 4 2 1 2 5 5 5 1 8

ppm gold (Au) 2 3 8 0 3 1 4 1 1 1 4 5 5 0 9

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What to do

• First match an assay sample with its location on the map - “Up the creek for minerals”. Using the key on the map, colour in the appropriate number of triangles, squares, rings or circles ***** For example: 3 parts per million will be lllmmm mmmm. Use different colours for copper, zinc and gold.

• When all the data is entered on the map, start from the widest downstream spot and

go upstream for each creek to where the metal assay values are highest. Shade in the area, or areas, of highest metal values (greater than 4)

Is this the same area for all the metals? ……………………………………………………………………………………………………….. ………………………………………………………………………………………………………..

• Compare these areas with the aeromagnetic and gravity surveys. Do they all point to the same areas as the best mineral prospects? Can you give reasons for what you have discovered. ……………………………………………………………………………………………………….. ……………………………………………………………………………………………………….. ………………………………………………………………………………………………………..

• Is there more than one prospective area? If so are they all the same size? Decide

which area you would like to survey in more detail (which is a slow and much more expensive stage of exploration) and give reasons for your choice. ……………………………………………………………………………………………………….. ……………………………………………………………………………………………………….. ………………………………………………………………………………………………………..

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10

WORKSHEET 6

ZEROING IN ON THE ORE BODY Now you have decided on the mineral prospect area, you will need to do some detailed exploration surveys to figure out the exact location, the depth, shape and size of the mineral zone, and the concentration of minerals within it. This requires a magnetic survey using a hand-held magnetometer. This survey is done by walking across the chosen area along closely spaced lines. The purpose is to find targets for drilling so that rock samples can be brought up and tested for metals. This information will help you decide whether or not to mine, and if it should be an open cut or an underground mine. What To Do

• The survey sheet shows a set of lines (called profiles) along a series of survey paths. Wherever the line bends upwards, there is an increase in magnetic strength. These areas are magnetic anomalies. Color in these anomalies, and label each with a name.

• If no part of the mineralised rock was seen at the earth’s surface, which anomaly would you

explore further by drilling? Remember that drilling is very expensive and slow, but is needed to get samples and find out how deep the ore minerals may be. …………..………………………………………………………………………………………… …………………………………………………..…………………………………………………

• Which anomaly will contain an ore body? Explain why.

……………………………………………………………………………………………………… ……………………………………………………………………………………………………… ………………………………………………………………………………………………………

• Go to the Diamond Drill Core Log Sheet and cut out the drill core log strips for each hole. • You will see that, at this stage, only the assay for gold has been completed. It is shown as a line

down the drill core sample log showing the concentration in parts per million. Colour in the area between the drill core and the wavy line showing the gold concentration.

• Tape the drill log strip to a drinking straw. Put a small piece of plasticine or blue tack on the

bottom end of the straw and stand the drill log vertically on the diamond drill hole (DDH) number shown on the Ground Magnetic Survey Sheet.

• Which anomaly has the gold ore body? Explain why you have chosen this one. Is it the same as

the anomaly you chose before you looked at the drill hole information? ……………………………………………………………………………………………………… ………………………………………………………………………………………………………

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• Look at the gold concentration pattern across all drill holes and describe what shape the ore body is. For example, would you describe it as a ball or sheet or a tube or scattered specks?

………………………………………………………………………………………………………

• Is the ore body flat or steeply dipping?

………………………………………………………………………………………………………

• At what depth does the ore body start? At what depth does the ore body finish? How thick is the

ore body? ………………………………………………………………………………………………………

• Should it be mined by open cut surface pit, or should it be underground shafts and tunnels?

………………………………………………………………………………………………………

• What else would you need to know before you make the decision whether to mine or not?

……………………………………………………………………………………………………… ……………………………………………………………………………………………………… ………………………………………………………………………………………………………

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WORKSHEET 7 ORE GRADE

The diagrams on the following pages show a few different rocks as a geologist would see them through a microscope. They contain ore minerals which are coded with a letter for colouring, using the key. For each sample, colour the various ores and mineral sands with different colours. Cut out all the pieces of the same ore or mineral and put them on the percentage grid to see what percentage (or parts in one hundred parts) of the rock they make up. You will need to put all the ore mineral pieces closely next to each other. Write your ore percentages in the table below

Percentage Composition % Sample

Malachite Nickel Zircon Ilmenite A

B

C

Answer these questions

1. Why is it useful to know the grade of a mineral ore?

……………………………………………………………………………………………………

…………………………………………………………………………………………………… ……………………………………………………………………………………………………

2. What % of the mineral sands is not useful ore?………………………… Add this to the % which is useful. (Total %……………..…..). Why does this not total100%? (Hint: imagine the sand grains as being as large as basketballs all in a large container. What would find between the balls?)

……………………………………………………………………………………………………

……………………………………………………………………………………………………

Use the sources to find out

3. What zircon and ilmenite are used for?

……………………………………………………………………………………………………

……………………………………………………………………………………………………

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Key Rock forming minerals Ores and mineral sands

Q

Quartz

Ni

Nickel

Py

Pyroxene

Z

Zircon

O

Orthoclase

L

Limenite

Am

Amphibole

Ma

Malachite (copper ore)

Pl

Plagioclase

M

Mica

L

Lime

G

Garnet

Ore Grade / Sheet 1

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WORKSHEET 8a

RAW MATERIALS I IRON ORE * What Makes an Ore Deposit Valuable

* Introduction:

Although minerals may be found in the ground at many locations throughout Australia, a mineral deposit may not be worth mining due to the costs involved being greater than the profit.

Things that determine the profitability of a mineral deposit include: • how concentrated the mineral is. (the grade of the ore) • where the deposit is located. (transport costs are a factor) • how easily the mineral can be extracted from the rock that surrounds it. • the current market value of the mineral

Types of Iron Ores include Haematite, Magnetite, Geothite, Siderite

Table 1: Iron Ore Classification Name Classification Theoretical Maximum

iron content (%) Haematite Fe2O3 72.4 Magnetite Fe3 O4 72.4 Geothite FeO.OH 62.8 Siderite FeCO3 48.3 Taconite Wide variety of iron-bearing rocks, usually

20 to 40% (actual). Jaspilite contains magnetite or haematite.

* Assuming no impurities present in the ore

Australia’s iron ore deposits are mainly Haematite and Geothite, and are some of the richest in the world. Geothite is softer and easier to crush than Haematite. Before they can be added to a blast furnace iron ore must be made into the right size (between 6mm and 35mm). Fine powdery iron ore needs to be made into pellets.

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WORKSHEET 8a

RAW MATERIALS 1 IRON ORE Exercise:- Iron Content of BHP Ores. The table below shows some typical figures for the iron content of ores from different parts of Australia. Use an atlas to locate Mt Newman, Yardi and Whyalla on the Map of Australia. Then, using the information from the table, construct a bar graph, showing the % iron content of each ore, as well as the total % of impurities, ie % of SiO2, Al2O3 , Mn, P, S and H2O all added together. Table 2: Typical analyses of BHP iron ores (%)

Iron Ore Fe SiO2 Al2O3 Mn P S H2O

Mt Newman High Grade Lump WA (H) 64.7 4.15 1.60 0.06 0.054 0.007 2.5

Mt Newman High Grade Fines WA (H) 62.0 5.55 2.60 0.04 0.069 0.009 2.2

Yandi Fines WA (G) 58.5 4.9 1.3 0.03 0.043 0.005 9.6

Whyalla Pelletising Fines SA (H) 62.8 3.76 1.85 0.27 0.050 0.033 3.12

Ore Type: H = Haematite, G = Geothite

Purity of Australian Iron Ores

Mt Newman High Grade

Lump

10 20 30 40 50 60 70 80 90 100 % composition

Mt Newman High Grade

Fines

10 20 30 40 50 60 70 80 90 100 % composition

Yandi Fines

10 20 30 40 50 60 70 80 90 100 % composition

Wyalla Pelletising

Fines

10 20 30 40 50 60 70 80 90 100 % composition

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WORKSHEET 8b

RAW MATERIALS II COKE Coke is made from coal. BHP uses coal from both Queensland and NSW. Once mined the coal is crushed and washed then baked in coke ovens for about 18 hours at temp of 12000ºc. This removes by-products, leaving black, granular coke. This coke is needed in the blast furnace to provide carbon for the chemical reactions that convert iron ore into metallic iron.

This can be expressed in the simplified word equation Iron Ore + Carbon Monoxide Iron + Carbon dioxide

FeO + CO Fe + CO2

About one tonne of coal makes about 0.8 tonnes of coke. Coking coal is used in steelmaking, and steaming coal is used to boil water to produce steam to make electricity. Coal is a non-renewable resource formed from the highly compressed remains of plant materials. Where you find coal seams in Australia, there were once widespread swampy forests growing. (250 - 300 m.y.a.) The widespread use of coal in NSW for both steelmaking and especially electricity generation has led many people to believe that this is a contributing to the greenhouse effect

Using the information above, design and construct a flow chart showing the steps whereby coal is converted to coke.

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WORKSHEET 9

METALS FROM MINERALS

When they are mined, most metals are bonded to chemical partners. In this experiment you will discover how metals can be freed from these chemical partners. You will need:

• safety glasses • a gas flame • matches • a heat proof mat • a beaker ½ filled with water • a paper clip • metal oxide powder

Method

Dip the end of a burnt match in water and then in the mineral oxide powder, so that the powder sticks to the moisture. Now put on safety glasses and put the end of the match in a gas flame. Repeat this a number of times. Look for any changes, and when you see a colour or shape change, the reaction is complete. Take the charcoal out of the flame, dip it in water and pick off the shiny bits with a paper clip. What to you think the shiny bits are? ………………………………………………………………………………………… ………………………………………………………………………………………… This is how metals are chemically separated from the chemical partners they have as minerals. Complete the sentence by unscrambling the words. The metal [edoxi] is burnt on [archloac] making [baconr] dioxide gas and pure [emtla]. This is called [temlings]. …………………………………………………………………………………………. ………………………………………………………………………………………… Why was the mineral crushed to a powder? ………………………………………………………………………………………… …………………………………………………………………………………………

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WORKSHEET 10 By-products - Internet Exercise:

Reduce Reuse Recycle Use http://www.aiw.org.au/kidszone to complete the following table.

By-Product From Use / Treatment Methane

Coalmining

Electricity

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The By-products of the Steel Industry BHP’s steel operations have created a significant by-products industry, in line with the company’s commitment to reuse materials rather than add them to the waste stream. Around 360 kilograms of by-products are produced per tonne of crude steel. These by-products are produced in the different stages of the production process including: the coal face, coke-making, iron –making, water treatment, sinter plant, steelmaking and in rolling mills. During each of these phases there is a conscious effort made to minimize waste, and where by-products are produced, to use them efficiently.

Process Primary Products By-Product Coal Mining Coal Washery Coke Ovens Sinter plant Blast Furnace Basic oxygen Steelmaking Slab caster Rolling mills Tin Mill

Coal Clean Coal Coke Sinter Molten iron Molten steel Steel slabs Rolled steel Tinplate Strapping

Methane Coal Wash Middlings Coke Ovens Gas BTX Naphthalene Tar Ammonium Sulphate Sinter fines Blast furnace slag Blast furnace gas Blast furnace dust Thickener slurry Steel furnace slag BOS dust Flue gas Slag rake/kish Tundish skulls Crop ends Caster scales Steel offcuts Mill scale Scrap offucts Recycle tin cans Oil Pickle liquor

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Coal Face to Coke Ovens Coal and coke production are not processes common to all integrated steelmakers. BHP’s Australian integrated steelworks have their own coke-making facilities. The modern integrated steelworks depends on coal as a source of carbon for chemical reduction of iron ore, and as a primary source of energy. Various marketable by-products become available as the coal is processed into coke. Using the fuel by-products of coal in the major steelmaking processes contributes significantly to limiting the cost of steel. Methane – Appin Colliery, located on the South Coast of NSW, produces high quality coking coal. A naturally-occurring by-product of the mining process is methane gas. At Appin, methane is now being converted to electricity. Ninety-four one-megawatt gas turbine engines have been installed and the electricity generated is sold into the NSW electricity grid to create power. The methane is drained from the coal seams before, during and after mining, with additional methane taken from exhaust ventilation air. This power is sufficient to service homes Coal Middlings – In order to minimize the level of ash that reaches the blast furnaces, coal is washed, and then blended with coal from different coal seams. The small size, high ash coal content is separated from the main coal stream fed to the coke ovens and is instead burnt in the coilers to generate steam and electricity, or exported as part of an energy coal blend. Coke ovens gas – During the coking process, coke ovens are heated by gases recovered from operations further down the line. But the gas produced by the coke ovens is itself also captured, cooled cleaned and recycled back into the system as energy for heating and electricity generation, replacing the need to purchase natural gas. Of the energy required to run the steelworks, up to 40 per cent may be provided by coke ovens gas (and up to an additional 40 per cent may be provided by blast furnace gas) When the coke ovens gas is cleaned, the process results in some valuable by-products which provide raw materials necessary for other industries:

• Ammonium sulphate us well known fertilizer used in both farming and in nurseries. BHP exports the ammonium sulphate produced at Port Kembla.

• BTX (a liquid consisting of benzene toluene and xylene) goes to the Chemplex plant in

Melbourne where it is turned into styrene monomer. This is used for plastic products like telephone handsets and is a vital ingredient of styrene cups and beads.

• Tar and naphthalene go to Koppers Australia in Newcastle. These products are used to

manufacture pencil pitch, which in turn is used to manufacture electrodes for the aluminium refining industry, plastics, paints and wood preservatives.

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Water Treatment A biological effluent plant, designed to treat waste water from the coke ovens, was constructed at Port Kembla in 1991 Using bacteria which thrive on a diet of cyanide, ammonia and hydrocarbons, the ‘bug plant’ removes 99 per cent of cyanide, 90 per cent of ammonia, 99 per cent of phenols and 99 per cent of thiocyanate found in the waste water. The bacteria are contained in tanks into which the water is pumped. Oxygen, phosphorus, lime and sulphuric acid are added. When the wastes are broken down by the bacteria, they are removed as a sludge which is squeezed dry and recycled to the coke ovens. The remaining water is filtered before being recycled or discharged safely. Sinter Plant Iron ore contains a high percentage of very fine material which is unsuitable for feeding directly into the blast furnace. In order to make use of this product, it is first agglomerated by mixing with fine lime and coke. It is then passed through a flame chamber where it ‘sinters’ (or fuses) together. The sinter plant is also used to recycle other iron or lime dusts generated by other process. Recycling by-product through the sinter plant is one way of recovering some of the fines produced in other parts of the steel making process.

IRON MAKING Slag – Slag is the bases for a multi-million dollar industry in Australia, and is a major by-products success story. BHP’s steelworks produce slag from two sources – blast furnace slag and steelmaking slag, Slag flows from the iron and steel furnaces as a molten mixture of limestone and the earthy components of iron ore coke, which have separated from the molten iron and steel in the furnace. It is then processed in tow forms. Rock slag is produced by allowing the molten material to cool slowly and solidify. It is then crushed, making it suitable for road bases and aggregates, Granulated slag is produced by the instant quenching of molten slag. The result is a sand-like product, which can be ground and used as a cement replacement in the concrete industry. In this application, it is favoured for its durability-particularly in marine environments. It can also be used as a sand substitute.

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Slag in this form has been used in projects such as the Sydney Harbour Tunnel, the third runway at Sydney Airport, the North West Shelf project, in the sea wall Slag in this form has been used in projects such as the Sydney Harbour Tunnel, the third runway at Sydney Airport, the North West Shelf project, in the sea wall of the Sydney Opera House forecourt, and as road paving for sections of the F4 Freeway (because of its anti-skid attributes) More recently, it has been used in the construction of the concrete walls, floors, columns and beams in the Wollongong Entertainment Centre (where it was favoured because of its reduced drying shrinkage properties and the proximity of the Centre to the waterfront), and in many of the Sydney 2000 Olympic Games venues, including the Equestrian Centre and Velodrome. Blast furnace gas and dust - Gas from the blast furnaces is sent into a gas cleaning plant where dust and fumes are removed. The cleaned gas is reused as fuel and the dry dust fed back to the sinter plant. In addition to coke ovens gas, a major part of the steelworks energy requirement is fueled by the cleaned blast furnace gas. The remaining slurry, which contains a zinc content too high to directly recycle, is put into a setting tank. Water is pressed out of the slurry, cleaned and put back into the harbour. The remaining fraction is stockpiled. BHP is looking at a process to economically retrieve the zinc and iron units.

STEEL MAKING Steel furnace slag - Slag from the basic oxygen steel (BOS) furnace has the metals removed and recycled back into the steelmaking process. This slag is used in road pavement, bottom ballast and aggregate in asphaltic concrete, and as landfill. BOS dust - This is removed from the exhaust gas of the BOS process in a slurry (or wet) form. It is mixed with the blast furnace slurry and treated the same way. Flue gas - It is not economically viable to recycle gas from the BOS furnace, so the gas is cleaned and then flared. Slag rake/kish - Fine graphite flakes are freed in small amounts from the slag-raking of ladles at the BOS. This material is not currently recycled. Caster scale - The continuous slab casting process produced caster scale, a fine iron oxide which flakes off the surface of steel. This is recycled back into the process by routes such as the sinter plant as a source of iron units. It is also useful in exothermic powders.

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ROLLING AND TIN MILLS Mill Scale - Mill scale is a by-product of the rolling process which is recycled in a similar fashion to caster scale. Pickle liquor - Pickle liquor is a hydrochloric or sulphuric acid solution used to clean strip steel after it has been rolled. These solutions are used by BHP Wire Products to clean the surface of rod and wire prior to wiredrawing or metal coating operations. In some wills, spent pickle liquor is passed through a recovery unit, returning the clean acid to the work baths, and generating a marketable ferrous sulphate product. In 1992, BHP joined with Orica and the NSW Water Board to convert some of this spent pickle liquor into a chemical that would greatly improve the quality of effluent from sewe4rage plants. It is used in sewerage treatment to break down detergents, washing powders and fertilizers that can cause excessive blue-green algae growth in the water system. The waste liquor (ferrous chloride) is converted to iron salts (ferric chloride) by Orica and is then used by the Water Board to bind and more easily remove solids from sewerage. As part of the arrangement, BHP used hydrochloric acid at the tin mill pickle line in Port Kembla. Using hydrochloric acid will also provide the by-product of caustic soda. Spent pickle liquor is also used at the Royal Australian Mint in Canberra, where it reduces the chromium (used to manufacture and clean coins) in waste water. BHP’s Western Port Works in Victoria converts most of its pickle liquor to hydrochloric acid at a regeneration plant. Here ferric oxide and hydrogen chloride gas are chemically produced and separated. The latter is absorbed in the rinse water from the pickle line and the hydrochloric acid returned to the pickle line. Ferric oxide powder is sold for use in a variety of industries, including the manufacture of audio and visual tapes, and electric motor cores.

THE FUTURE A number of other used for by-products are in planning, or still in their infancy. These include: Soil substitute - BHP has developed a special soil substitute, which is a combination of coal washery refuse, granulated blast furnace slag and sewerage sludge. It has been used in reforestation projects at the steelworks involving hundreds of thousands of Australian native trees and shrubs.

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Coal Wash - Coal wash is the dirt and shale washed out of coal before it is sent to the coke ovens. It is currently used as landfill and as an ingredient in the BHP soil substitute. Other potential uses are being investigated, including application as a construction material. Oils - Increasingly stringent requirements on the disposal of wasted to landfill has prompted a search for suitable treatment options. In the past, BHP has used a process in which waste oily sludges removed from steel rolling mill coolants are treated biologically to produce a product that can be successfully incorporated in soil mixes, and also enable the coolant to be recycled. The solids in the coolant are removed by centrifuge and magnetic separations. The resulting waste sludge contains high levels of tallow and mineral oils, solids and water. By mixing the sludge with granulated slag in a bioreactor, the oil and grease content can be reduced to the extent that the resulting material has a soil-like consistency. It can then be used as a component of the substitute soil mix. The tallow oil purchased by BHP for use as a rolling lubricant is itself a recycled product of the fast food industry – cooking oil. Recycled oil is also returned to the plant through the coal preparation area, where it is added in the coal grinding process at the hammer mill as a means of increasing the built density of coal charged into coke ovens.

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WORKSHEET 11

ENERGY

Energy Use in Australia

1. Use the following information to construct a pie graph of energy use in Australia.

Energy source % use renewable 6.0 crude oil 36.4 black coal 28.4 brown coal 11.1 natural gas 18.2

Sources: Australia Bureau of Agriculture and Resource Economics & Australian Bureau of Statistics

(a) What are the two main sources of energy in Australia?

…………………………………………………………………………………

(b) What percentage of Australia’s energy come from fossil fuels?

…………………………………………………………………………………

(c) What percentage of Australia’s energy come from renewable sources?

What renewable sources do you think are being used in Australia? ………………………………………………………………………………… …………………………………………………………………………………

2. Use the following information to construct a pie graph to show what energy is used for in

Australia.

Energy use % agriculture 3 mining 4 production of metals 16 commercial 4 residential 13 other industry 21 transport 39

(1) What are the two main areas of energy use is Australia?

…………………………………………………………………………………

…………………………………………………………………………………

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WORKSHEET 12

ENERGY SOURCES

Think about the features of the renewable energy sources that you have identified in class. Decide which features are advantages and which are disadvantages. List the features under the following two headings.

Source Advantages Disadvantages Solar Wind Waves Tidal Geothermal Hydro-electricity

……………………………….. ……………………………….. ……………………………….. ……………………………….. ……………………………….. ……………………………….. ……………………………….. ……………………………….. ……………………………….. ……………………………….. ……………………………….. ………………………………..

……………………………….. ……………………………….. ……………………………….. ……………………………….. ……………………………….. ……………………………….. ……………………………….. ……………………………….. ……………………………….. ……………………………….. ……………………………….. ………………………………..

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ENERGY

• Some features are advantages and some are disadvantages. Have students complete the worksheet: Features of Renewable Sources.

Some suggested answers are as follows.

Source Advantages Disadvantages Solar Wind Waves Tidal Geothermal Hydro-electricity

renewable, pollution-free good for small scale technology renewable, quite, comparably low cost, pollution-free, land beneath windmills can be used for other things, good for small scale ‘windfarms’ renewable, low cost renewable, pollution free reliable, constant source, renewable in the long term, cost effective renewable, pollution free, reliable and continuous source

occupies large expanses of land, there is a need to store the energy because of limited heating hours, needs lots of sunny days with no clouds, not cost effective at present need a lot of windmills to get a useful amount of energy, can be expensive to build tall towers, need wind mainly blowing from one direction so limited areas are suitable, wind speeds must be more than 21 kph, back up provisions are needed, can be visibly disturbing on a large scale, can interfere with TV and microwave transmission need strong waves, need constant waves all year round only available on certain coastlines, need very fast tide in and out, building of barrages across an estuary can be ugly, not cost effective at present local use only, has an unpleasant odour, contains harmful gases such as NH3, suitable hot spots in the Earth’s crust don’t occur everywhere, there is a need to dig deep into the Earth’s crust need a constant water supply, need hilly terrain, can be costly to pump water up to top of hill, not suitable in day, flat continents, large scale accident risk, large scale environmental damage, high initial building costs

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