Extracting metals from ores - PowerPoint Presentation

1. Extracting metals from oresGradeObjective Outcomes7-9To be able to evaluate alternative biological methods of metal extraction, given appropriate information.To be able to identify different methods of metal extraction from metal oresTo be able to conduct an experiment to demonstrate how electrolysis is used to extract copper metal.4-6To be able to explain and evaluate the processes of bioleaching and phytomining.1-3Starter:Describe two methods of desalination, which converts salty water to potable water.What is the difference between pure water and potable water?Name three steps which take place during the treatment of waste water, before it is released into the environment.

2. Predict the discovery dates of calcium, aluminium, silver and goldTask: Describe the relationship between when the metal was discovered and its reactivityMetalDiscovered duringPotassium (K)1807Sodium (Na)1807Calcium (Ca)Magnesium (Mg)1755Aluminium (Al)Zinc (Zn)1746Iron (Fe)5000BCLead (Pb)7000BCCopper (Cu)9000BCSilver (Ag)Gold (Au)Increasing reactivity

3. The more reactive the metal the later it was discovered. This is due to the metals reacting with oxygen and water, so can’t be found in their pure state.What is the relationship between when a metal was discovered and it’s reactivity?

4. More reactive metals occur in rocks as compoundsRocks that are mined for metals are called ores. Copper, zinc & iron ores are examples.RockCopper

5. Extracting copper from copper-rich oresCopper-rich ores are a finite resource, they are being used up very quickly and the methods which we use to extract the copper metal can be energy-intensive, expensive and polluting to the environment.Two methods that are currently used:Smelting – this involves heating the copper ore up to very high temperatures which produces impure copper. This is then used in the process of electrolysis to extract the pure copper metal. Sulfuric acid is used to make copper sulphate solution, which is then used in electrolysis to extract the copper metal.

6. Task: In pairs, read the information about the extraction of metal from copper-rich ores and answer the following questions:What is one negative point of the extraction process?Explain why copper ions are lost from the anodeExplain why pure copper atoms build up at the cathode.

7. Self-assessment:What is one negative point of the extraction process?Explain why copper ions are lost from the anodeExplain why pure copper atoms build up at the cathode.When the copper ore is heated to a very high temperature in the blast furnace, alongside limestone and sand, it produces sulphur dioxide - a pollutant.Electrons are lost from the anode (negative electrode) and move towards the cathode (positive electrode). This forms Cu2+ ions at the anode which then dissolve into the solution.The Cu2+ ions which have formed at the anode and then dissolve into the solution, will now move towards the cathode (negative electrode). When these ions reach the cathode, they will gain electrons to become copper atoms.

8. Investigate: Extracting copper from malachite+-Malachite is a type of copper ore which contains copper carbonate.Follow the method below to extract copper from this ore:Heat copper carbonate in a boiling tubeCopper oxide will be left in the tube, CO2 gas will also be given offAdd dilute sulphuric acid to the copper oxidePlace a stopper in the boiling tube and shake gently – this makes copper sulphate solutionPlace a funnel over a new boiling tube and line this with filter paper, pour the copper sulphate solution through to remove any unwanted copper oxide. Set up the equipment shown in figure 1, turn the power on until you can see copper metal collecting at the electrode. Which electrode does the copper metal form on? Can you explain why this happens?Copper sulphate solutionCarbon electrodes

9. What did you find?CuCuCuCuThe copper sulphate solution contains Cu2+ ions which will be attracted to the negative electrode (cathode). Here they will gain electrons to form copper atoms, so pure copper metal can be extracted from the negative electrode.

10. Task: Watch the video and answer the following questions:What is a low-grade copper ore?What is the problem with extracting copper from low-grade copper ores?Describe the process of phytomining.Describe the process of bioleaching.At the end of phytomining and bioleaching, what methods can scientists use to extract copper from its compound?What are some of the advantages of biological extraction methods such as phytomining and bioleaching?https://www.youtube.com/watch?v=b5RVPauf4oM

11. Self-assessment:A low-grade copper ore is an ore which only contains a small amount of copper.It is harder to extract the ore economically from these ores.Phytomining – plants are grown on land which contains the metal compound that we want. The plants take in the metal compound, which is stored in their tissues. The plants are then harvested and burned; the ash contains a high concentration of the metal compound.Bioleaching – bacteria is mixed with the metal ore, chemical reactions take place which leads to the production of a solution called leachate. The leachate contains the metal compound that we want to extract.The copper metal can be extracted by electrolysis or by a displacement reaction using iron. These methods allow for economical extraction of metals from the metal compounds. Also, they do not involve digging, transporting or disposing of large amounts of rock like traditional mining.

12. Plenary: Key WordsWrite a list of key words from the lesson today!

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16. What is a low-grade copper ore?What is the problem with extracting copper from low-grade copper ores?Describe the process of phytomining.Describe the process of bioleaching.At the end of phytomining and bioleaching, what methods can scientists use to extract copper from its compound?What are some of the advantages of biological extraction methods such as phytomining and bioleaching?What is a low-grade copper ore?What is the problem with extracting copper from low-grade copper ores?Describe the process of phytomining.Describe the process of bioleaching.At the end of phytomining and bioleaching, what methods can scientists use to extract copper from its compound?What are some of the advantages of biological extraction methods such as phytomining and bioleaching?

17. Copper extraction from copper-rich oresSmelting copperCopper ore is heated to a very high temperature within a furnace, with limestone and sand. These reactions produce molten copper and sulphur dioxide.The copper that is produced is impure, it must be purified before it can be used to.Refining impure copperCopper can be purified using electrolysis. The electrolyte used is copper sulphate solution, the two electrodes will be the impure copper (anode – positive electrode) and pure copper (cathode – negative electrode).As electricity is passed through the circuit the copper atoms at the impure anodes will lose electrons, thus forming CU2+ ions which dissolve into the solution. Any impurities will fall to the bottom.Meanwhile, at the pure copper cathodes the copper ions will gain electrons, forming copper atoms, which build up more copper on the cathodes.Very pure copper at the cathodeSolution containing copper ionsSludge containing precious metalsImpure copper anode get smaller as it loses copper ions+-