System and method for recovery of valuable constituents from steel-making slag fines

Abstract

A system and method directed to the economical recovery of valuable iron constituents from iron blast furnace and steel-making slag fines wherein the slag is obtained and subjected to a series of classification steps which progressively sort the slag fines by various physical characteristics, including magnetism, size, and density, into relatively iron-rich and relatively iron-poor classifications, resulting in the isolation of iron-rich commercial byproduct at one or more of the classification steps.

What is claimed is: 
     
         1 . A method for recovering iron-rich material from iron blast furnace and steel-making slag fines comprising:
 a) classifying a selected input batch of material based upon its magnetic properties into a magnetic material group and a non-magnetic material group;   b) classifying a selected input batch of material based upon its size into a relatively larger particle-size group and relatively smaller particle-size group; and   c) classifying a selected input batch of material based upon its density by introducing the material as a slurry into a hydraulic fluidized bed separator.   
     
     
         2 . The method of  claim 1  wherein the magnetic material obtained in step a) is supplied as the selected input batch for classifying step b). 
     
     
         3 . The method of  claim 2  wherein the relatively larger particle size group is greater than about 10 mm. 
     
     
         4 . The method of  claim 2  wherein the relatively smaller particle-size material obtained in step b) is provided as an input batch to be crushed in a grinding or milling operation. 
     
     
         5 . The method of  claim 4  wherein the crushed material is provided as an input batch for classifying step b), and wherein the resulting relatively smaller particle size group is provided as an input batch for classifying step c). 
     
     
         6 . The method of  claim 5  wherein the relatively larger particle size group resulting from classifying step b) is greater than about 1 mm. 
     
     
         7 . The method of  claim 6  wherein the relatively larger particle size group is provided as an input batch for classifying step a). 
     
     
         8 . The method of  claim 1  wherein the classifying steps are performed in the sequence a), then b), then c), and wherein the input batch for classifying step b) is the magnetic material group obtained from classifying step a), and the input batch for classifying step c) is the relatively smaller particle-size group obtained from classifying step b). 
     
     
         9 . A method for recovering iron-rich material from iron-making and steel-making slag fines comprising subjecting the slag fines to a series of classification steps which progressively sort the slag fines by various physical properties of the material, including magnetism, size, and density, into relatively iron-rich and relatively iron-poor classifications, wherein at least one of the classification steps includes introducing the slag fines as a slurry into a non-compressible fluid fluidized bed separator to separate relatively lower density and relatively higher density constituents of the slag fine particles suspended within the fluidized bed. 
     
     
         10 . A system for recovering relatively iron-rich material from slag fines, the system including:
 a magnetic classifying station for receiving a first batch of material and separating the particles in the first batch into magnetic and non-magnetic groups;   a first size classifying station for receiving a second batch including the nonmagnetic group, and separating the particles in the second batch into a group of particles of size greater than or equal to about 10 mm and a group of particles of size less than about 10 mm;   a milling station for receiving a third batch including the group of particles of size less than about 10 mm and milling the particles in the third batch;   a second size classifying station for receiving the third batch and separating the particles in the third batch into a group of particles of size greater than or equal to about 1 mm and a group of particles of size less than about 1 mm; and   a hydraulic fluidized bed density separator for receiving a fourth batch including the group of particles of size less than about 1 mm and separating the particles in the fourth batch into a group of particles having a density in the range of about 5.0-6.0 g/cm3 and a group of particles having a density in the range of about 2.3-2.7 g/cm3.