In the midst of working on the second in the Mesabi Project historical novel series, I turned another year older. To celebrate, my family and I rented a small tear-drop trailer and drove to the Michaux State Forest in Pennsylvania. There we parked the Little Guy in the campground of the Pine Grove Furnace State Park and discovered how pleasant it was to have an enclosed bed and heat. That first night the temperatures dropped into the low teens. The condensation from our combined breaths froze to the inside of the windows.
When the sun finally crept over the tall, straight pine trees that surrounded the campground the air temperature warmed a bit and we hiked to the Pine Grove Furnace, an old iron furnace where the raw iron ore that was excavated from the ground in the surrounding mountains was cooked at high temperatures and formed into chunks of solid pig iron that could be used in manufacturing. This was the way iron was process before the days of iron ore mining in northern Michigan and Minnesota. The iron furnaces, before the proliferation of railroads which could carry the ore across long distances, were located near the source of iron itself, near the mines.
The furnace itself is a huge mason oven, wide at the bottom and narrow at the top. The raw materials were dumped in layers of ore and coal from a platform built over the top of the furnace itself. The coal was made locally, from wood also harvested from the same forest as the iron ore itself. Vents pumped air into the base of the oven so that temperatures inside could reach up to 3,000 degrees Fahrenheit. The ore melted as the temperatures rose, and the liquid, mixed with impurities—called slag—like dirt and non-ferrous rock, dripped out into long stone furrows. Workers scraped the slag off the top of the liquid and then channeled the pure iron into casts.
Sometimes the furnace could clog if the temperature dropped, or if too many impurities found their way into the molten metal. If this happened, a huge chunk of iron and rock weighing upwards of five thousand pounds—called a salamander—could solidify in the base of the furnace. Getting the salamander out often required the partial dismantling of the inner oven.
This system for making iron from raw ore was all but eliminated by the 1880s as railroads offered a cheap method of transporting ore to centralizing processing facilities. Dozens of furnaces could be set up to process thousands of tons of ore per day. And caches of iron ore were discovered in places like Tower, south of Lake Vermillion, and Mountain Iron, and Virginia. For the iron from the Mesabi Range, the process of turning ore into usable iron had to change dramatically. The wet, loose iron ore from the pits on the Mesabi clogged traditional iron furnaces. For a time, manufacturers like Carnegie and a steel man named Henry Oliver were reluctant to buy the new Mesabi iron ore. But when it became apparent that the ore from the Mesabi was so abundant, businessmen saw profit and changed their manufacturing process.