Pelletized composition for molten metal de-oxidation

Abstract

One aspect of the present invention relates to compositions of a pelletized form which are well suited for use as inoculants in the manufacture or casting of molten metals. A further aspect of the invention relates to a method of making such pelletized compositions from waste materials which bear silicon carbide or both silicon carbide and silicon.

What is claimed is: 
     
         1 . A pelletized composition made according to a method comprising the steps of:
 (a) providing a material containing moisture and at least: (i) silicon carbide or (ii) both silicon carbide and silicon;   (b) heating said material under a vacuum to dry said material to a total moisture content of less than fifteen percent by weight;   (c) mixing said material with a binder to form a mixture;   (d) pelletizing said mixture to agglomerate said particles to form a plurality of discrete pellets of at least one desired size, each of said pellets including a plurality of said particles, and   (e) hardening said binder to strengthen said pellets.   
     
     
         2 . A pelletized composition as claimed in  claim 1  wherein said binder material comprises a thermoset binder present in an amount effective to produce said pellets having a compression strength of at least eight pounds per square inch after said hardening step has been carried out. 
     
     
         3 . A pelletized composition as claimed in  claim 1  wherein said pellets have an axial ratio of less than or equal to one point three to one after said hardening step has been carried out. 
     
     
         4 . A pelletized composition as claimed in  claim 1  wherein said pellets have a said moisture content of less than or equal to two percent by weight after said hardening step has been carried out. 
     
     
         5 . A pelletized composition as claimed in  claim 1  wherein said material comprises, by weight percentage of total solids, any combination or subcombination of the following which totals one hundred percent by weight:
 twenty percent by weight to eighty percent by weight silicon carbide; 
 zero percent by weight to fifty percent by weight silicon; 
 less than five percent by weight carbon; 
 less than ten percent by weight iron, and 
 less than one percent by weight of other impurities. 
 
     
     
         6 . A pelletized composition as claimed in  claim 1  wherein said binder comprises calcium lignosulfonate in an amount effective to yield said pellets having a compression strength of at least eight pounds per square inch after said hardening step has been carried out. 
     
     
         7 . A pelletized composition made according to a method comprising the steps of:
 (a) providing a material containing moisture and which includes at least silicon carbide and moisture, said moisture including at least one organic;   (b) heating said material under a vacuum to dry said material to a total moisture content of less than fifteen percent by weight, said vacuum being sufficient to lower a boiling point of said organic below a decomposition temperature of said organic, said heating being carried out at a temperature which exceeds said boiling point of said organic under said vacuum but does not exceed said decomposition temperature of said organic.   (c) mixing said material with a binder to form a mixture;   (d) pelletizing said mixture to agglomerate said particles to form a plurality of discrete pellets of at least one desired size, each of said pellets including a plurality of said particles, and   (e) hardening said binder to strengthen said pellets.   
     
     
         8 . A pelletized composition as claimed in  claim 7  wherein said hardening step comprises the step of heating said pellets after said pelletizing step to reduce said moisture present in said pellets to less than or equal to two percent by weight. 
     
     
         10 . A pelletized composition as claimed in  claim 7  wherein said binder material comprises a thermoset binder present in an amount effective to produce said pellets having a compression strength of at least eight pounds per square inch after said hardening step has been carried out. 
     
     
         11 . A pelletized composition as claimed in  claim 10  wherein said binder comprises calcium lignosulfonate. 
     
     
         12 . A pelletized composition as claimed in  claim 7  wherein said pellets have an axial ratio of less than or equal to one point three to one after said hardening step has been carried out. 
     
     
         12 . A pelletized composition as claimed in  claim 7  wherein said pellets have a said moisture content of less than or equal to two percent by weight after said hardening step has been carried out.