Tin-bismuth solder steel recycling contamination

25 years prior (~early 1990s) push to replace lead-tin solder with bismuth-tin. Steel industry resistance: 10 ppm bismuth makes steel ingot unrollable (grain-boundary embrittlement, no recovery path except re-mining). Used to illustrate that environmental substitution decisions must consider downstream recycling.

I've got a couple of examples. One has to do with steel and recycling of steel. Both of these have to do with lead, actually. A few years ago they wanted to get the lead out of the solder in electrical connectors, because lead's toxic. So they were going to replace lead-tin solders with bismuth-tin solders. The steel companies almost had a fit. Because you start putting bismuth-tin solders in automobiles, which are a major part of the recycling of steel scrap, and you make all of the scrap worthless. If you get 10 parts per million bismuth in a steel ingot, it's just a big paperweight. You cannot roll it — it's just brittle. The bismuth goes to the grain boundaries and there's no way to get it out. You can't oxidize it out. You have to go back to the ore. You can purify it out of the ore, but you can't get it out by just remelting the steel. There is no way to do it.