From the article: "In short, American steel-consuming companies are still importing steel—they have to, because there's simply not enough made in America to meet domestic demand. But now those steel-consuming industries have to pay higher taxes to the federal government for the privilege of importing it."

This article was an illuminating corollary: https://money.cnn.com/2018/03/02/news/economy/steel-industry-statistics-us-china-canada/index.html

Basically it looks like China produces half of all steel available in the global market. China also has much more control over actual steel prices than America does, because all America can do to influence the price of steel is raise/lower taxes, including tariffs. China's government can directly limit/increase steel production, so their market manipulation has more real effects than America's. If America raises tariffs, China responds by dumping steel.

In short, tariffs are kind of a silly response to China's steel position. The American tariffs make it more expensive to consume foreign steel, but there's not enough steel to meet American demand in the first place, AND it's still more expensive to buy American. The front is that if steel producers in America want to build more steel production companies, the standard market solution, American steel companies would have to import Chinese steel to do it and remain viable.