Process selection in steelmaking — phosphorus in pig iron Evaluate the statement: “The acidic Bessemer (converter) process is suitable for producing steel from pig iron that contains large quantities of phosphorus.” Choose the correct judgment.

Introduction / Context:Phosphorus is a harmful impurity in most steels, promoting cold-shortness and brittleness. Whether a steelmaking route can remove phosphorus depends strongly on slag chemistry and converter lining (acidic versus basic). Understanding this compatibility is central to selecting the right process for a given hot metal composition.

Given Data / Assumptions:

• “Acidic Bessemer” uses silica (acid) refractory; “basic Bessemer” (Thomas) uses basic linings and fluxes.
• High-phosphorus pig iron requires efficient dephosphorisation.
• Slag basicity governs P removal thermodynamics.

Concept / Approach:Phosphorus is removed effectively only in a basic environment where basic oxides (from lime/dolomite) form stable phosphate compounds that partition into slag. Acid-lined converters cannot sustain the lime-rich slags necessary for dephosphorisation, so the acidic Bessemer route is unsuitable for high-P pig iron. The basic (Thomas) process was developed specifically to handle such charges.

Step-by-Step Solution:Identify requirement: remove high P.Check slag chemistry: needs high basicity (lime).Acidic lining is incompatible with high-lime slags → poor P removal.Therefore, the statement is incorrect; use the basic process instead.

Verification / Alternative check:Historical practice in Europe used the Thomas basic converter to treat high-phosphorus minette ores successfully, confirming the principle.

Why Other Options Are Wrong:Options implying “correct” conflict with slag chemistry; adding lime in an acid converter damages the lining; sulfur co-presence does not change the need for basic slag.

Common Pitfalls:Assuming oxidation alone removes P; without basic slag, P removal is inefficient.

Final Answer:Incorrect