What’s so good about coke made from coal

Q: After touring the grounds of the historical Coke Ovens Park in Dunlap, Tenn., I wondered how and why coal was turned into coke. They employed more than 300 people at one time. In Granite City there was an old plant called the coke plant. Is coke used in the making of steel?

A: Hamburgers and pizza aren’t the only things in this world that go better with coke. Although its use has dropped more than 80 percent since the late 1950s, coke was an essential ingredient in turning the U.S. iron and steel industry into a powerhouse more than a century ago, which explains its need in Granite City.

In essence, coke is kind of a purified coal. It’s made by baking your basic bituminous coal in an airless furnace or oven at temperatures as high as 3,600 degrees but usually about 2,000 degrees. From a ton of coal, this baking will burn off about 600 pounds of impurities, including crude coal tar, light oils and ammonia, which can be further refined to obtain various chemical products. What you’re left with, then, is 1,400 pounds of carbonized coal, which is commonly called “coke.”

Not all coal is suitable for coke-making. Called “coking coal” or “metallurgical coal,” it must meet certain criteria for moisture, ash, sulfur, tar and volatile content. But the coal that passes muster produces a coke that began replacing charcoal as the primary fuel at U.S. steel foundries in the 1880s.

Coke, you see, is an ideal fuel for this industry. If you would burn plain coal in blast furnaces, you would produce massive amounts of smoke from all of those impurities that were burned off in the coke-making process. So coke not only generates intense heat, it is also nearly smokeless. Plus as the coke burned in a typical foundry furnace, it would remove the oxygen from the iron ore, converting it to metal. According to the U.S. Department of Energy, it takes about a half ton of coke to produce a ton of crude pig iron.

In addition, coke can be used in the smelting of phosphate rock to produce phosphorus and calcium carbine. It can also be used as a source of heat for producing metal castings and apparently is a favorite fuel for blacksmiths who don’t want to choke on coal smoke all day.

By the end of World War I, 88 percent of the nation’s iron and steel was being produced with coke. As you might imagine, this required the production millions of tons of coke each year in what was likely a miserable job of continually feeding coal into ovens and removing the coke and waste.

But the demand for coke eventually started to slow. Where you visited, for example, the 268 beehive ovens went cold in 1927 when the price of coal collapsed and mining ceased. Since the late 1950s, the amount of coal used for making coke has dropped from 25 percent to 4 percent.

The reasons are many, not the least of which is the decline in iron and steel production. In addition, improved blast-furnace technology has reduced the amount of coke needed to produce a ton of pig iron, and modern steel-making processes can replace pig iron with scrap iron and produce steel from scrap iron, recycled steel and iron pellets.

Still, SunCoke obviously saw a need when it opened its new plant in Granite City seven years ago. To find out more, go to www.suncoke.com or www.wva-usa.com/history/mthope/coke.php.

Q: How do you test the accuracy of a carpenter’s level?

A: After finding the same answer from many sources, I figured it had to be on the level even though I first thought it was just too darn simple. Here’s what you do, according to Johnson Level and Tool Manufacturing Co. in Mequon, Wis.:

To check the horizontal vial, simply put the level on a flat surface as if you were actually going to take a level reading. Make two pencil marks — one at an end of the level and another along the side of the level where the vial is. Take a reading where the bubble is in relation to the lines on the vial. Now, simply rotate the level 180 degrees side to side and align it with your original marks. The bubble should be in the exact same spot you saw it the first time. If it’s not, it’s time to head to the hardware store for a new level.

The same can be done to check your vertical vial. Hold the level against a wall or other vertical flat surface. Make those two marks as described above. Look at the vial and note the bubble’s position. Now, rotate the level 180 degrees side to side, align it with your marks and note the bubble’s position. Again, it should be exactly the same. If not, throw it out before your next construction project turns into the Leaning Tower of Pisa.

If it makes it easier, here’s a slight alternative: If your horizontal surface isn’t level, place thin pieces of wood or cardboard under one end or the other until the bubble is squarely in the middle. Then, when you rotate the level 180 degrees, you’ll again be looking for the bubble to be in the middle.

If my description still has you scratching your head, you can always turn to a video demonstration at YouTube.com. Search for “Checking a Spirit Level.” I recommend the ones from Rob Beckett (from the government of South Australia) or Adrian Sayres. By the way, levels can go bad, so you might want to check it out before buying a used level or even after buying a new one so you can return it. For more information, try the Johnson website at www.johnsonlevel.com.

Today’s trivia

What role did coke (yes, carbonized coal, not the soft drink) play in the U.S. lunar and Martian space missions?

Answer to Sunday’s trivia: On Aug. 27, 1998, Nintendo of America launched the Pokemon video game phenomenon in Topeka, Kan. Thousands of children and adults lined up at the city’s Forbes Field to help launch a $17 million advertising blitz for a craze that had taken over Japan in less than 24 months. There was a parade of 10 bright yellow VW Beetles along with Pokemon dances and cartoons. And in a final surrender to the invading animated critters, Topeka Mayor Joan Wagnon officially declared the new name for the state capital would be — what else? — ToPikachu (for a day, at least) as a flag bearing Pikachu’s image and the words “In Pokemon We Trust” was hoisted up the flagpole.

This story was originally published August 23, 2016 at 9:13 AM with the headline "What’s so good about coke made from coal."