Processing of steel making slag

Abstract

A system for processing slag material from a steelmaking process includes reducing the average particle size of slag from a steelmaking process into finer particle size material by directing the slag against a surface at a velocity sufficient to cause the slag to break into smaller pieces, and separating the finer particle size material into at least an iron rich product and a silicate rich product based on the differences between these products in at least one or more properties including magnetic susceptibility, particle size, weight or specific gravity. Directing the slag against a surface to reduce the average slag particle size can better separate the dissimilar materials in the slag from each other, and result in less dust generation and less energy consumption compared to grinding the slag material.

1 . A process, comprising:
 reducing the average particle size of slag from a steelmaking process into finer particle size material;   separating the finer particle size material into at least two different product groups based on the differences between the materials in the product groups in at least one or more properties including magnetic susceptibility, particle size or specific gravity; and   moving at least a portion of the finer particle size material in enclosed tubes among a plurality of workstations wherein it is separated into different product groups.   
     
     
         2 . The process of  claim 1  wherein a negative pressure source is communicated with the product groups to remove the smaller particles and dust from the product groups. 
     
     
         3 . The process of  claim 2  wherein the negative pressure source includes one or more cyclones. 
     
     
         4 . The process of  claim 2  wherein after the smaller particles and dust are removed from one of the product groups, the material in that product group is transferred to a subsequent workstation by a conveyor. 
     
     
         5 . The process of  claim 4  wherein the subsequent workstation includes a magnetic separator wherein the material is exposed to a magnetic field to separate the more magnetically susceptible materials from less magnetically susceptible materials. 
     
     
         6 . The process of  claim 5  wherein the magnetic separator includes a supply of forced air directed on the material to assist the separation of the materials based on magnetic susceptibility. 
     
     
         7 . The process of  claim 1  wherein a forced air flow is communicated with the product groups to remove the smaller particles and dust from the product groups. 
     
     
         8 . The process of  claim 7  wherein the forced air flow is generated by an air heater to provide a heated air flow to the slag material. 
     
     
         9 . A process, comprising:
 reducing the average particle size of slag from a steelmaking process into finer particle size material;   separating the finer particle size material into at least two different groups using a first aspirator that applies forced air flow to the material so that a first group may be separated from a second group by the air flow;   moving the first group to a separation device that further separates the first group into at least two separate groups; and   moving at least a portion of the second group to a magnetic separator.   
     
     
         10 . The process of  claim 9  wherein the separation device is a cyclone that separates certain particles from other particles. 
     
     
         11 . The process of  claim 10  wherein at least some of the particles in the first group are moved to a forced air flow device to separate that material into two groups based on the flow rate of the forced air flow, and the two groups so separated are separately moved to subsequent stations for storage or further processing. 
     
     
         12 . The process of  claim 9  wherein the second group is moved to a size reducing device which reduces the average particle size of the material before at least a portion of the material in the second product group is sent to the magnetic separator. 
     
     
         13 . The process of  claim 12  wherein after being reduced in size, the material of the second product group is separated into a group having a smaller average size and a group having a larger average size. 
     
     
         14 . The process of  claim 9  wherein at least some of the slag material is routed to multiple size reduction workstations which each further reduce the average particle size of the slag material and after slag material passes through each size reduction workstation the material is routed to a device that separates the material it receives into one group of larger and heavier particles and another group of smaller and lighter particles. 
     
     
         15 . The process of  claim 14  wherein the smaller and lighter particles are routed to one or more filters. 
     
     
         16 . The process of  claim 13  wherein the group having a smaller average size is routed to one magnetic separator and the group having a larger average size is routed to a different magnetic separator. 
     
     
         17 . The process of  claim 16  wherein said one magnetic separator uses a lower magnetic field strength than said different magnetic separator. 
     
     
         18 . The process of  claim 9  wherein the separation device utilizes a magnetic field to cause the separation of the first group into two separate groups.