en.wikipedia.org/wiki/Bessemer_process

Two independent histories contradict the claim that Bessemer's Sheffield partnership in 1858 was the first commercial production.

• Thomas J. Misa's A Nation of Steel says Bessemer's Sheffield works did not initially make finished Bessemer steel directly from the converter. In its first year, the works produced pellets that were then remelted in crucibles. Misa adds that "Only after a visit in 1859 from the Swede Göran Göransson, the first licensee to make commercial quantities of the new steel, did Bessemer begin producing steel directly from the converter".
• Sweden's National Museum of Science and Technology (Tekniska museet) likewise states that Göransson "became the first ironmaster in the world to successfully make steel using the Bessemer method."

So the Sheffield partnership may have begun operations in 1858, but calling it the first commercial production is incorrect: the earliest successful commercial Bessemer production is credited to Göransson in Sweden, not to Bessemer's Sheffield works in 1858.

The sentence gets the key distinction wrong.

Authoritative steel-industry explanations describe the Bessemer process as removing carbon by blowing air through molten pig iron. Modern basic oxygen steelmaking is the same basic converter idea refined by using pure oxygen instead of air.

• worldsteel says the Bessemer process is "blowing air through molten pig iron to oxidise the material and separate impurities."
• The same organization says basic oxygen steelmaking is a refined Bessemer-type converter that "uses oxygen rather than air to drive off excess carbon."
• Material World likewise summarizes the historical sequence as: "Bessemer's converter of 1856 established the principle - air blown through molten iron burns the carbon out" and later "Substituting pure oxygen for air" created the modern process.

So the improvement was oxygen instead of air, not a change from blowing gas to adding "oxygen-carrying substances."