Available online
Description
The programme uses Ellingham diagrams to show how one can predict the conditions under which various compounds tan be reduced to metal.
The programme uses Ellingham diagrams to show how one can predict the conditions under which various compounds tan be reduced to metal.
| Module code and title: | T352, Materials processing |
|---|---|
| Item code: | T352; 04 |
| First transmission date: | 10-04-1979 |
| Published: | 1979 |
| Rights Statement: | |
| Restrictions on use: | |
| Duration: | 00:24:00 |
| + Show more... | |
| Producer: | Nat Taylor |
| Contributors: | Peter Lewis; Frank Sale |
| Publisher: | BBC Open University |
| Keyword(s): | Ellingham diagrams; Free energy scale; Kinetics; London Scandinavian Mettallurgical Company (Rotherham); Metal extraction; Reduction process; Thermodynamics |
| Footage description: | Film shots of an iron blast furnace. Sale introduces the programme. Frank Sale examines the relative stabilities of magnesium and gold oxides by applying heat to magnesium turnings and a gold ring. He then ignites two separate trails of magnesium turnings. Finally he heats a sample of mercuric oxide in a test tube. In order to get a quantitative measure of thermal stability, Peter Lewis points to an Ellingham diagram (Free energy diagram) for mercuric oxide. The diagram becomes animated with commentary by Lewis. Frank Sale applies heat to a sample of litharge (lead oxide) and notes the effect. Peter Lewis then examines an Ellingham diagram for litharge to explain the effect produced. Sale next heats litharge in the presence of carbon and molten lead is produced. Peter Lewis, with Ellingham diagrams (still and animated) explains the effect of carbon on the above experiment. He then goes on to explain how zinc oxide is reduced to metal. Commentary and Ellingham diagrams are interspersed with film of a lead blast furnace and a zinc separation. Frank Sale explains that some metals cannot be reduced by using carbon as a reducing agent. These metals form very stable carbides instead. He suggests that hydrogen may be an effective reducing agent in such cases. Sale demonstrates showing a test tube containing tungsten trioxide which has had hydrogen bubbled through it. The tube contains all the intermediate oxides on the way to obtaining metallic tungsten. An animated Ellingham diagram with commentary by Peter Lewis shows the tungsten reduction process. Still shots of a rotating tube furnace, a machine used for the industrial reduction of the tungsten trioxide. Commentary by Frank Sale explains the process. He goes on to explain why reducing agents such as aluminium and silicone are used when hydrogen will not work. He demonstrates by igniting pellets of iron oxide and aluminium powder. The reduction of Cr2 O3 with aluminium powder is shown on an Ellingham diagram. Lewis sums up the programme. |
| Master spool number: | 6HT/72757 |
| Production number: | 00525_5328 |
| Videofinder number: | 1431 |
| Available to public: | no |
