How did the basic Bessemer process make Luxembourg’s iron ore useful for steelmaking?

The iron ore deposits found in the southwestern region of Luxembourg were historically difficult to use for steelmaking because they contained high levels of phosphorus.3

The original Bessemer process utilized a converter lined with acidic, siliceous material. This lining was incompatible with the basic flux (such as lime) required to remove phosphorus, as the resulting slag would have degraded the furnace walls.1

In 1879, the introduction of the basic Bessemer process—developed by Sidney Gilchrist Thomas and Percy Gilchrist—solved this issue by using a basic refractory lining made of calcined dolomite. This modification allowed for the use of a lime-rich slag that could effectively hold phosphorus and sulfur in solution, thereby enabling the successful refinement of Luxembourg’s phosphoric iron ores into steel. This technological advancement was the catalyst that allowed Luxembourg’s metallurgical industries to flourish.123