Refining agent and refining method

Abstract

A refining agent containing Al, MgO and CaO as main components, wherein dolomite is a MgO source and a CaO source. When the refining agent is supplied into molten iron, Mg vapor is produced due to a reaction in the molten iron, and causes a refining reaction by the Mg vapor.

1 . A refining agent containing Al, MgO, and CaO as main components, and including a material as a MgO source and a CaO source, in which MgO and CaO are close to or in contact with each other in a minute state, the refining agent being arranged to produce Mg vapor due to a reaction in molten iron, when the refining agent is supplied into the molten iron.  
   
   
       2 . The refining agent according to  claim 1 , wherein the refining agent is for desulfurization and/or deoxidation of molten iron.  
   
   
       3 . The refining agent according to  claim 1 , wherein the refining agent contains MgO, CaO, and Al summing to 75 mass % or more.  
   
   
       4 . The refining agent according to  claim 1 , wherein the material which is a MgO source and a CaO source is dolomite.  
   
   
       5 . The refining agent according to  claim 4 , wherein the refining agent is for desulfurization and/or deoxidation of the molten iron.  
   
   
       6 . The refining agent according to  claim 4 , which is in a state prepared by mixing or crushing and mixing a raw material including the dolomite and an Al source containing 25 mass % or more metal Al, or a raw material including at least one of another MgO source and another CaO source in addition to them, to obtain a mixture powder with an average particle size of 1 mm or less, or in a state prepared by changing the mixture powder into a pelletized or lumped form with a size of 3 mm to 40 mm.  
   
   
       7 . The refining agent according to  claim 6 , wherein the raw material is in the pelletized or lumped form and includes a forming binder mixed therein.  
   
   
       8 . The refining agent according to  claim 7 , wherein the binder has a viscosity of 2 to 10 poise at 60° C.  
   
   
       9 . The refining agent according to  claim 4 , wherein a mass ratio of Al/MgO is 0.05 or more, and a mass ratio of CaO/MgO is 0.5 to 10.0.  
   
   
       10 . The refining agent according to  claim 9 , wherein the mass ratio of Al/MgO is 0.2 or more.  
   
   
       11 . The refining agent according to  claim 9 , wherein the mass ratio of CaO/MgO is more than 1.5 and up to 10.0.  
   
   
       12 . The refining agent according to  claim 9 , wherein the mass ratio of CaO/MgO falls in a dolomite composition range.  
   
   
       13 . The refining agent according to  claim 9 , wherein the MgO source and CaO source are formed of dolomite and another MgO source or CaO source for compensating for part of the CaO and MgO, which exceeds dolomite composition, so as to obtain a predetermined mass ratio of CaO/MgO.  
   
   
       14 . The refining agent according to  claim 4 , which contains MgO, CaO, and Al summing to 75 mass % or more.  
   
   
       15 . A refining method of performing a desulfurization treatment of molten pig iron comprising adding a refining agent to molten pig iron held in a container, wherein the refining agent is the refining agent according to  claim 1 .  
   
   
       16 . A refining method of performing a desulfurization treatment of molten pig iron comprising adding a refining agent to molten pig iron held in a container, wherein the refining agent is the refining agent according to  claim 4.