There has been a shift in steel production, from iron-ore based toward recycled-based over the last 20 years. Generally speaking, the recycled steel is much cheaper to make (for obvious reasons) and some US firms such as NuCor have popped up, without union labor, to fill the need.
The old-line steelmakers who 'do it from scratch' (USSteel, Bethlehem, Wheeling-Pittsburgh) are generally union shops and have a lot of very expensive equipment, not to mention mines, ships to transport ore, etc., etc.
The Chinese have also discovered recycled steel and are buying scrap like there's no tomorrow. THIS has raised the price of scrap, thus raising the price of recycled steel.
Now even NuCor is hurting for margin, because some buyers of their product have long-term contracts binding NuCor to a fixed price.
...For high end of threat levels, we utilize the only certified armor plate manufacturer in the market today, Clifton's High Hard Ballistic Steel. Clifton's is the only actual armor plate on the market today. Competitors of this manufacturer use steel renamed as "wear plate" as their version of armor plate. Wear plate is used to protect dump truck beds and bucket liners in the mining industry.This material is manufactured from start to finish to meet MIL-A-46100D and MIL-A-46177B Armor Plate as per the rigorous U.S. Military's Armor Specifications. It is tested at Aberdeen Proving Grounds to meet the military standards. Once the product conforms to the MIL standards, it must pass additional ballistic testing to meet the Underwriters Laboratory and National Institute of Justice standards. These standards are met through independent tests at certified laboratories.
The new producers were cheaper because they were more productive labor-wise since they weren't locked into old time labor contracts and were not burdened with costly health and pension payments. Materials for an integrated mill were and are cheaper than scrap, which is why a good integrated mill located close to the sources of its materials will always be more efficient than a scrap fed mill.
There is also the little issue of sourcing scrap if you do not forge new iron. The mini-mills are only able to exist because we either import pig iron or steel slabs, or make it ourselves.
Lastly, mini-mills benefit from lower transportation costs in regions without integrated mills, because many of them have been built in areas of the country devoid of natural resources, but which still have a ready market for product. The integrated mills are mostly tied to the Great Lakes and the Quebec and Minnesota Iron Ranges, and therefore their nearby customer base of midwest auto plants and appliance/office furniture manufacturers.