Fume dust suppression during pouring of molten metal, and apparatus

Abstract

Fume dust is prevented when molten metal is poured into a vessel, and water or water mist is sprayed into the vessel or onto the molten metal, creating a reduced level of oxygen concentration of about 12% by volume, preferably about 8% by volume, inside the vessel or at the molten metal surface.

What is claimed is:  
     
         1 . A method of limiting or preventing generation of fume dust during handling of molten metal, comprising the steps of generating steam by spraying water or water mist when molten metal is being poured into a vessel, and controlling the amount of steam introduced into said vessel or at a surface of said molten metal that the oxygen concentration inside said vessel or at said surface of said molten metal is reduced so as to essentially prevent creation or oxidation of fine molten metal particles in said vessel or at said molten metal surface.  
     
     
         2 . The method defined in  claim 1 , wherein said oxygen concentration inside said vessel or at said molten metal surface is reduced to about 12% by volume or less.  
     
     
         3 . The method according to  claim 2 , wherein said oxygen concentration is reduced to about 8% by volume or less.  
     
     
         4 . The method according to  claim 1 , wherein said water and a gas are simultaneously supplied to said spray when said water is supplied to said water spray, so as to spray water mist, 
 and wherein the supply of said gas is essentially stopped to convert to use of water spray substantially independently of gas spray.    
     
     
         5 . The method according to  claim 4 , wherein said water mist is sprayed into said vessel before pouring molten iron therein, and wherein water is sprayed after said pouring of molten metal begins.  
     
     
         6 . The method according to  claim 1 , wherein said water spray is provided to spray water or water mist; and wherein gas is supplied to said water spray prior to supplying said water, after which spraying of water or water mist is begun.  
     
     
         7 . The method according to  claim 6 , comprising the further step of detecting said water pressure, and the further step of activating said water spray, when said pressure is at a set level or higher.  
     
     
         8 . The method according to  claim 1 , wherein water and gas are simultaneously supplied to said water spray after spraying water, so as to convert the spraying process from spraying of water to spraying of water mist alone before stop spraying.  
     
     
         9 . The method according to  claim 1 , wherein a water spray is provided to spray water or water mist; and wherein the supply of water to the spray is stopped and gas is supplied to said spray, thus purging the water spray of water.  
     
     
         10 . The method according to  claim 1 , wherein said spraying is conducted under conditions wherein sprayed water particles have a particle size causing them to be practically completely vaporized when water particles are sprayed into contact with molten metal.  
     
     
         11 . The method according to  claim 10 , wherein said spray is formed at a location spaced apart from said molten metal, and wherein said molten metal is located at another location and maintained in an atmosphere at a temperature at said other location, and wherein said sprayed water particles are sprayed in a manner to form a particle size which is based on the distance between the spraying location and the molten metal surface, and is also based on said atmosphere temperature.  
     
     
         12 . The method according to  claim 10 , wherein the particle size of said sprayed water particles is controlled on the basis of the following formula:  
         r≦kL ( T -100)  wherein r designates the particle size of said sprayed water particles; L designates the distance between said spraying location and said molten metal surface; T designates said atmospheric temperature; and k represents a particle size determination constant, and    wherein the value of r is about 500 μm or above.    
     
     
         13 . The method according to  claim 1 , wherein water or water mist is sprayed upon said molten metal flow while said metal is pouring into said vessel.  
     
     
         14 . The method according to  claim 1 , wherein said oxygen concentration in said vessel is reduced before beginning the step of pouring said molten metal into said vessel.  
     
     
         15 . The method according to  claim 14 , wherein said oxygen concentration in said vessel is reduced by spraying water mist into said vessel before beginning the step of pouring said molten metal.  
     
     
         16 . The method according to  claim 1 , comprising the steps of: 
 supplying gas to a water spray device which is provided so as to spray water or water mist to a molten metal flow and/or said vessel, before pouring said molten metal; supplying water to said water spray device to spray water mist into said vessel; stopping the introduction of gas supply after initiation of pouring said molten metal so as to convert to water spray only and spraying water to said molten metal flow and/or said vessel; and supplying gas to said water spray before completion of pouring said molten metal, thereby converting water spray to water mist spray, and then stopping the supply of water after completion of pouring while continuing the flow of said gas so as to purge said water spray device with said gas.    
     
     
         17 . The method according to  claim 1 , wherein said molten metal contains carbon.  
     
     
         18 . The method according to  claim 1 , wherein said molten metal is selected from the group consisting of molten iron and molten steel.  
     
     
         19 . The method according to  claim 1 , including the further steps of measuring the oxygen concentration in said vessel and controlling operational conditions of said spraying based upon oxygen concentration reduction.  
     
     
         20 . An apparatus for limiting or preventing formation of fume dust in pouring molten metal into a vessel; said apparatus comprising a water supply and delivery system, a separate gas supply and delivery system, and a spray device connected for spraying water or water mist and aimed at the surface of said pouring molten metal flow as said molten metal is poured into said vessel, both said water supply and said separate gas supply being connected as feeds into said spray device to create a water mist.