 Next, we write down extraction of silver. The ore we use for this process is Argentite ore. You must remember this name also. What ore we are using for extraction of this silver copper and all. Argentite ore we use. The formula of Argentite ore is what? Can you tell me? What is the formula of Argentite ore? AG2S. Correct. The formula is AG2S and we do the extraction of silver by cyanide process. This process we also call it as MacArthur and forest process, which is not important obviously. Write down in this silver compound, write down in this silver compound dissolved in sodium cyanide. In this silver compound dissolved in sodium cyanide, which forms a complex salt, which forms a complex salt. The formula of the complex salt is an A AG CN2. This is the complex salt forms. In this sodium silver compound dissolves in sodium cyanide and forms a complex salt in presence of air. Now by addition of zinc, silver precipitated from this complex. See the flow sheet here. First of all, we will have this Argentite ore AG2S and we will do the concentration of it. Concentration of ore. The method we use here again is flow flotation. Yes, it is. Flow flotation process. In this what happens, you see the reaction here. The powdered ore that we have, we add some water into it plus we will add pine oil and air. Same process again. And again in this what happens the froth carries sulphide particles that will take out and will have that concentrated ore. After this concentrated ore or concentration process, next we have is like I said cyanideation. And for this cyanideation process, we add sodium cyanide into it. AG2S and we add NACN into it. Sodium cyanide. Reversible reaction and we get complex of sodium cyanide N AG CN whole twice plus sodium sulphide Na2S. This molecule, we call it as sodium Argento cyanide. The complex is sodium Argento cyanide. This Na2S, another reaction we have, Na2S sodium sulphide combines with O2 in presence of H2O, converts into Na2SO4 NaOH with sulphur. Now the next method we have precipitation. We will filter it and we will get this compound. And then we have precipitation of silver with zinc with the help of zinc. Reaction in this process is two molecules of Na AG CN2 plus ZN and it gives silver metal plus Na2 ZN CN4. Basically it is a displacement reaction. So zinc is what? Zinc is more electropositive. Zinc is more electropositive. Then AG silver and hence displaces it. The AG that we get here is dissolved in alkali solution, alkali nitrate like KNO3 and we get AG metal on cooling. Last step here is, again like I said, electro-defining. And for this the anode is again impure metal, cathode is pure metal and electrolyte we use here is AG NO3 with HNO3. Pure silver deposited at cathode and in this pure AG, then all of you next one write down extraction of zinc. For extraction of zinc, we can use many metals here, many ores here. Like we can use zinc blend, ZNS, we can also use zinc, zincite, ZNO, we can also use kalamine which is ZNCO3. Kalamine also when you heat this, it converts into ZNO and CO2 and then we use the process as ZNSite that also we can do. So extraction of zinc, it's very simple and very easy this one is. The extraction of zinc involves, first of all again the same thing, the concentration of ore. Suppose I am taking zinc blend ZNS and we'll do the concentration of this ore and concentration here it is done by gravity settling process. Gravity method I'll write down that again we have discussed. Gravity settling, first we'll use gravity settling, after this we'll use flot flotation, both we can use here, gravity settling and then flot flotation. One more thing here you must write it down, if Fe2O3 present as impurity, as impurity present then we use magnetic separation method, if it is present. But generally we use gravity method or flot flotation. So concentration we do by this and then we get concentrated ore, concentrated ore is then we'll use roasting of it. Roasting is heating at high temperature in presence of oxygen. So the reaction here is you write down ZNS plus O2 gives ZNO plus SO2. ZNS some part of it also converts into zinc sulfate, ZNSO4. ZNSO4 then on high heating again converts into zinc oxide ZNO plus SO2 plus O2. Eventually we are getting oxide, sulphur dioxide and all. And generally we heat this at 900-2000 degrees Celsius. Copy down this we'll go to the next page. Then next step will have reduction. The zinc oxide that forms here get reduced with carbon and forms ZN plus CO, carbon monoxide. Or if you take CO it also converts into ZN with CO2, carbon dioxide. So we get this metallic zinc at around 1500 degrees Celsius. So when you get this zinc which is impure, so to get pure zinc here we'll do the electro refining of this. The last step is electro refining. Electro refining anode we use as impure zinc plate cathode we use pure zinc plate. Electro light we use here is ZNSO4 with dilute H2SO4. And the zinc metal obtains at cathode pure zinc. That is the method of extraction of zinc. Done all of you? Okay. One last question for today. You tell me the reason here. Sinabar and Galena on roasting often gives their respective metals. But zinc blend does not. Can you tell me the reason for this? What is the reason? First of all, what is this Sinabar? Sinabar is HGS, Galena is PBS and zinc blend is ZNS. So on roasting what happens when you heat this at high temperature it actually forms oxides. So the reaction we have ZNS, sorry, the reaction we have HGS heated with HGO oxides of it. It gives HG plus SO2. Right, so two molecules of this and three molecules of this we get. When you have PBS plus PBO. So we'll get 3PB plus SO2. ZNS plus ZNO, 3ZN plus SO2. Right, so here the reason is the oxide of HGO and PBO is unstable. This HGO is unstable. PBO is also unstable oxide. But ZNO is stable. Since it is unstable, so it converts into this HG. So this reaction possible, this reaction possible. It is already stable, so this reaction won't take place. And that's why we won't get zinc metal in this reaction. So this reaction is not possible. So reduction of ZNO into this is not possible since ZNO is already stable. Got it? Yeah, right, right. That's the reason. So that is the application of Illingham diagram. Because you should know this a bit. Which one is up, which one is down, that gives you this information. Understood? All of you? Right. Okay, so guys we'll wind up the class here. Right, there are few more metals given in NCRT extraction of that. You can go through on your own. Okay, and that will finish the entire chapter. Okay. If you have any doubt, we can discuss that also next class. Otherwise we'll go with amines or any other chapter like biomolecules. Okay. But you must read NCRT for these kind of chapter. NCRT is more than enough. Okay. Finish NCRT completely for metallurgy. Understood? Okay guys. Thank you. Thanks a lot for joining. See you.