17/05/2016 cgrahamphysics.com Extracting Metals

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1 Extracting Metals

2 Which country is the leading producer? Copper Philippines Chile Gold China Nickel Mexico Platinum Titanium Silver South Africa Australia Diamond Australia, Chile, China, Mexico, Philippines, Russia, South Africa Russia

3 Aim Describe the extraction of Iron. Describe smelting of copper through the use of carbon. Key words Exothermic Ore Native metal Reducing agent Smelting

4 Have you ever wondered Are all metals found in the Earth s crust? The bigger picture Only gold, silver, copper and the platinum metals occur in nature in larger amounts.

5 Remember: Properties of Metals Most transition metals have these general physical properties They also react slowly or not at all with oxygen, water and 17/05/2016 acids cgrahamphysics.com 2016

6 Different properties Maybe we don't want these properties. Maybe we want something that isn't so hard and isn t so heavy. What can we do? We could make an alloy. Define an 'alloy'? An alloy is a mixture of metals. Can you remember some examples of alloys? Brass (copper & zinc), Bronze (copper & tin), Stainless steel (iron, chromium & nickel), and Amalgam (mercury, silver, copper & tin)

7 Iron is not a native metal. It can be found in ores, that is in mixture with other materials To get the pure iron, it needs to be extracted from the ore Extracting Iron You need very high temperature to extract the iron Iron oxide + carbon iron +CO 2

8 The Blast Furnace The ore with coke and lime stone are fed in at the top Hot air is blasted from the bottom Oxygen from the air reacts with coke to form carbon dioxide This is an exothermic reaction heat is released The heat is used to drive the reaction Carbon dioxide reacts with more coke and forms carbon monoxide

9 continued Carbon monoxide is the reducing agent: it causes iron to lose the oxygen Pure iron is left, which runs to the bottom of the furnace Limestone removes the impurities, which are collected as molten slag and will run off as it is lighter than the pure iron

10 Example of metal extraction The ore is lead oxide (Massicot) PbO. Carbon is more reactive than lead. What will happen? Lead oxide + carbon carbon dioxide + lead What type of reaction is this? Can you write the balanced symbol equation? 2PbO + C CO 2 + 2Pb

11 In theory Iron Oxide + carbon Iron + carbon dioxide Very high temperature is needed Cannot be replicated in the laboratory Practical: copper oxide + carbon Copper + carbon dioxide

12 Practical Copper oxide can be reduced just like the blast furnace by heated Carbon powder.(smelting) Reduces to form Copper and carbon dioxide in an exothermic reaction. Make approximately 1 spatula of each and MIX VERY WELL. 2 Extra spatulas of Carbon should provide a layer to stop any oxygen getting to the reaction. Hold the boiling tube at an angle and heat vigorously ALONG THE WHOLE TUBE until it ALL GLOWS RED.(5 min at least) Warning: Don t just heat the bottom as it can superheat and expand quickly Tip contents immediately into a beaker of cold water + decant black carbon off carefully and look for copper metal. Carefully place Reddy brown copper on tissue paper for inspection.


14 Plenary: MWB Draw a blast furnace and explain how iron is extracted from its ore How can you extract lead from lead oxide?

15 Key words Exothermic a reaction accompanied by the release of heat Ore - a naturally occurring solid material from which a metal or valuable mineral can be profitably extracted Native metal - any metal that is found in its metallic form, either pure or as an alloy, in nature Reducing agent - a substance that tends to bring about reduction by losing oxygen Smelting - extract (metal) from its ore by a process involving heating and melting