Dephosphorization


Also found in: Dictionary.

Dephosphorization

 

a set of physicochemical processes that facilitate the removal of phosphorus from a metal (cast iron or steel) during smelting. It is usually achieved by oxidizing the phosphorus to its pentoxide, P2O5, which passes into the slag, where it is permanently fixed as tetracalcium phosphate, 4CaOP2O5.

References in periodicals archive ?
In melting of metal in furnaces with basic lining conditions of dephosphorization are the most favorable within the period of the charge melting, which is characterized by low temperature of the metal and its high oxidation.
Dephosphorization of the metal in the process of melting is more efficient if oxidizing atmosphere, high activity of iron oxides in the slag, sufficiently high basicity of the slag, presence of slags with insignificant content of phosphorus, replacement of the slag, and low temperature of the metal are ensured.
It is established that kinetics of dephosphorization is determined by content of oxygen in boundary layers of the metal, degree of oxygen transition to the contact surface, on which phosphorus oxidation reaction takes place, degree of phosphorus transition to the same surface, and reaction proper of phosphorus oxidation with formation of phosphoric anhydride.
Rate of dephosphorization is expressed by the following formula:
where dP/d[tau] is the rate of dephosphorization,%/s; [[O].
Calculations, carried out by the authors, allowed drawing conclusion that the limiting stage of the metal dephosphorization is diffusion arrival of oxygen to the surface, on which the reaction proceeds.
So, certain regularities of the metal dephosphorization in blowing of the molten pool by gas-reactant mixtures may be extended to the process of liquid-phase melting.
Analysis of Table 2 shows that as amount of carbon in the alloy increases, intensive reduction of carbon by iron from the oxide takes place, which retards process of the alloy dephosphorization.
Process of ferronickel dephosphorization in basic converter during its blowing by oxygen under high-basicity slag with high content of (FeO) may be presented in general form by the following summarized reaction [5, 8]: