Actually, modern steel mills arent very labor intensive at all.
Read the excellent book about Nucor, The Legend of Nucor, and you would be amazed how few guys it takes to run a modern, computerised mill.
Needless to say, all of the new mills being built in the USA are highly automated.
While the chinese and other third world countries were buying used steel mills 20 years ago, virtually everybody, worldwide, who is building new mills today is building very high tech, low labor mills.
The biggest cost is energy, and a modern mill uses a lot less energy than a used USS mill that was built in the fifties.
The reason the foreign companies and american companies like Nucor keep building mills here in the USA is because shipping costs on steel are a much bigger component than the labor cost differential for most types of steel.
Krupp is sending up billets from Brazil for their new mill because they have a newish, state of the art primary mill in Brazil with government subsidised cheap energy. If they could get really cheap power here, many companies would probably build new primary mills here- we have, after all, lots of taconite ore here.
One thing to remember though, is that our days as the number one consumer of steel are long gone, never to return. China now consumes about the same amount of steel as the USA, and produces more. In the old days, we consumed more steel than anybody else, by far- so we were the dominant market, and it made sense to make the steel here.
Nowadays, China, India, the middle east, and other developing countries are consuming far more steel, combined, than we do- so it is only natural that steel producers will build mills near the markets.
With today's energy prices, its unrealistic to expect we would export much steel, even if we had the capacity to make it. Which we dont- we make less than we use.
Companies will continue to build mills here to supply domestic demand, but not much for export- some high end, specialty stuff, but ordinary steel will be made in the countries that use it, more and more. Steel is a source of national pride to produce, and every major country, like India or China or even Brazil, wants to make it at home.
In general, we are still thinking like we are top dog, but sheer numbers mean we are less and less important in the overall scheme of things- the total population of the USA is about equal to the plus or minus error in calculating China's population.