The Carrie Furnaces Tour

Last night when I was planning what to do today and tomorrow, I took into consideration which days the places I want to see are open.  The Carnegie Science Center is open during the day every day, and the city Inclines are open every day and night, but the Andy Warhol Museum is closed on Tuesdays and the Carrie Furnaces Tours aren't available on Tuesdays or Wednesdays.

So my plan for today was to take the Carrie Furnaces Tour, then visit the Andy Warhol Museum, and then ride the two inclines up the mountain. I also read that Pittsburgh has the steepest street in the continental United States, so if I'm in that area today, my plan is to stop and see that street.

I'll cover the Carrie Furnaces in this post, and will do a separate post for today's other activities.

-- Carrie Furnaces Industrial Tour --

The Carrie blast furnaces have been declared a National Historic Landmark. They were part of the U.S. Steel Homestead Steel Works. The furnaces at this site were built in the early 1880s and operated until 1982. Southwestern Pennsylvania was the steel making capital of the world from 1875 to 1980. At its peak, the Carrie furnaces produced over 1,000 tons of steel per day.

Our tour guide's name is George. His father worked at the furnaces as a supervisor, and got him a job to earn money  for college -- so he  had first hand experience. George taught school for awhile after graduation, but at some point went back to the blast furnaces because it paid better. 

The furnaces made iron from iron ore, coke, and limestone. The iron ore came by ship across the great lakes from Minnesota, and then by railcar to the blast furnaces. Coke, sometimes referred to as metallurgical coal, is made by heating low-sulphur bituminous coal to get pure carbon. The coal came by rail from Pennsylvania coal fields, and was burned in "beehive ovens" to produce coke. The limestone came by rail from quarries in the Penn State are of Pennsylvania. Limestone is used as a flux to bind the iron and carbon, and to pull out impurities. Below is a basket of coke they use for demonstrations.

At first, the plant made "merchant iron", which means it sold bars of "pig iron" to the highest bidder. There was a famous Homestead steel strike in 1892 across the river. Andrew Carnegie bought the site in 1898 and made it a part of Homestead steel. He built a "hot metal bridge" to carry the molten iron in rail cars across the river to his steel works.

The Carrie site had 7 furnaces that operated 24/7, but only furnaces #6 and #7 are still standing and are part of the tour. Below are some diagrams of the site, and the steel making process. The structures still remaining are highlighted in yellow.

Here is my summary of the iron making operation...

The long buildings in front generated power and powered fans that provided air that circulated in the furnaces.

Three stoves were staged to feed the air to each furnace. The stoves and furnaces were all lined with waffle-shaped refractory brick. While one stove was heating up its brick with gas, hot air was circulating from the second (already heated) stove into bottom of the furnace, and the third stove was cooling down. A worker opened and closed the gas valves and air ducts so the stoves took turns at each role, allowing the furnace to operate 24/7.

Meanwhile, the iron ore, coke, and limestone were dumped from the rail cars, and loaded onto a conveyor in percentages based on the steel recipe, and dropped into the top of the furnace. 

The hot air was pumped into circular tubes at the bottom of the furnace, and circulated upwards.

When the iron was ready, workers opened holes in the bottom of the furnace, and the molten iron and slag flowed through channels, where the lighter slag was directed away and the iron flowed into the top of refractory-brick-lined rail cars. The rail car in the photo below is rotated to its side so you can see the opening. The rail cars were sent across the hot metal bridge to the steel works, where alloys are added to make steel. 

The furnaces operated at 1800 degrees, and the hot air was circulated between 50,000 and 79,000 cubic feet per minute! The refractory brick had to be replaced from time to time.

Four tons of input material produced 1 ton of iron, 1/2 ton of slag for impurities, and the rest went up in smoke. Pittsburgh was a smoky city! (Snow wasn't white... it was grey or red.) It took 5 million gallons of water a day to keep things cool, and the water was dumped into the river.

The workers were mostly immigrants that left their home countries due to famine or to find a better life. The first immigrants came from Germany and Ireland. Famines in Ireland and Eastern Europe brought many others. The workers lived in houses by the river, below the tracks, where the water was toxic. Disease was common, and the child mortality rate was high. The workers weren't unionized until 1932.

Carnegie eventually sold U.S. Steel to J. P. Morgan, and used much of his money for charitable purposes. He built 1700 libraries in the United States, built libraries in other countries, built museums, etc.

As you can tell from my above description, I found the furnaces and iron making process fascinating!

Along the outer wall, near where the trains used to carry the ore, there is an artistic wall. Out guide told us that very year they whitewash the wall and have a festival where local artists can add new art. The site adopted the "Carrie furnaces Steel Worker" artwork, painted by one of the artists, as one of their site logos.

As an aside, a friend of mine sent me a link to a podcast where a professor wanted to make a toaster from its elemental components. He started by making iron for the steel heating elements. He got iron ore from a mine, etc. He didn't have much success. He got as far as making iron, but it was not malleable. The iron shattered when he tried to shape it!