字幕列表 影片播放 列印英文字幕 It's quite difficult to get into places like this. You have to remove everything metallic. I'm not even wearing a belt. I'm a bit worried that my trousers might fall down, that would be a first for Periodic Videos I'm really excited. I've got here more than one and a half million pounds' worth of platinum group metals. never had so many in front of me all at once and we're here at Johnson Matthey Noble Metals and they've allowed us to see all sorts of parts of the factory but just to warm up as a sort of side show we have here five kilos of gold and another five kilos in a packet. These are each worth £150,000, so reasonable house just to get started. We're here at a place where they're processing these metals here: Rhodium, Iridium, Palladium and Platinum. And the reason that they're called noble metals is that they don't react with oxygen easily In fact platinum is one that really even at high temperatures doesn't form oxides the other ones can form oxides Gold doesn't form oxides, gold is over here and is close to these but is not normally considered a platinum group metal Noble is an old-fashioned word meaning it doesn't react a posh way of saying, "chemically boring." The noble gases--they didn't think reacted with anything. Now they know some of them do, but noble is dismissing them as being worthy but boring The important thing about the noble metals, the platinum group metals is they're fantastic catalysts they can be used for all sorts of applications, making nitric acid, cleaning up car exhaust and many other applications So of course, in all this processing, they generate dust. And most of it is caught, but some of it you can't avoid going into the air and falling to the floors . So some of it collects on our shoes So when you go in and out, they have special brushes to clean the bottom of your shoes, and they recover really quite a large amount of metal each year, worth more than a decent sized car What they're doing in this factory is taking this material, which is called sponge which is what comes from the mines. This is platinum sponge here and in this bottle here is rhodium sponge and it's much finer because rhodium is the last element to come out of the process in the mines. So they take this sponge and turn it into grains, rather like this. Here are grains of platinum this is probably the only time in my life that I will be able to play with platinum in such a casual way and over here--I'll use the other hand so I don't mix them up-- are similar sorts of grains of iridium. but they're very much heavier. They turn this sponge into those grains by heating it up to high temperature melting it, and then pouring the molten liquid out and it's fantastic, you see this liquid that's so hot, it's bright red and then it's cooled down rapidly to form the grains and then the grains can be taken and melted and cast into ingots a large lump and here we have an ingot of platinum This weights 13 kilos and you can see I can't lift it up with one hand with two hands I can just about start lifting it The difference between this and gold is that you can use platinum as a catalyst for all sorts of chemical processes so ingots like this are then turned into bars like so first of all by hammering the ingot very hard with a heavy hammer when it's really hot And the fantastic thing is at it hammers it, the metal gets hotter the energy of the hammer is turned into heat it starts glowing redder and redder and then they take the hammered bar and draw it down through a series of dies so it first of all gets into a coil like this and as the coil comes out of the die it coils itself up. It's almost like magic, you see this coming out and going round and round and round I was mesmerized. And then they take this heavier bar and put it through a series of dies 'til in some processes it gets narrower than my hair. I didn't actually take out a hair to measure, but I believe them. And I couldn't see it, easily. The braider is much better with his lens and saw it. Once they've got these fibers, these wires, they can then start making all sorts of materials. They can knit the fibers together or weave them, just like you do with cloth to make fine meshes, which are used in the chemical industry for catalyzing reactions. Particularly, for example, turning ammonia into nitric acid This process that we've all read about in books ammonia going into nitric acid, but actually to see these huge pieces of fiber woven together, and what's so interesting is that they're so thin You imagine, when you see a huge chemical plant, that it's full of catalysts, whereas in fact the operating catalyst is really quite thin, and the reaction takes place very fast and you need the rest to warm it up and cool it down afterwards It's important to stress that in the mines for the platinum group metals, and the main mines are in South Africa in Russia, some are in Zimbabwe, and some are in Canada in all these places, the amount of platinum group metals in the rock is very very small to make an ounce of this sponge you require somewhere between 10 and 40 tons of rock. A huge amount. And the other thing, the processing is not instantaneous, once you've got the rocks out, to get the platinum material, takes about six weeks of processing, letting things settle, processing some more and rhodium takes another fourteen weeks, so twenty weeks, nearly half a year to get the rhodium once you've dug the rocks to this stage but once it gets here, they can process things really quite quickly. Some of the samples we saw when we arrived are already being processed. Had to get us another ingot of platinum, the one we saw has already gone into the factory. 94% platinum, 6% rhodium, and part of the reason for this is that rhodium is a much rarer element and also that people have found platinum, with a bit of rhodium gives particularly good...
B1 中級 超級昂貴的金屬 - 視頻週期表 (Super Expensive Metals - Periodic Table of Videos) 1 0 林宜悉 發佈於 2021 年 01 月 14 日 更多分享 分享 收藏 回報 影片單字