An Experimental Investigation Into The Separation Of Ferrous Substance From Converter-steel Slag

An experimental project has been carried out for separating ferrous substance from the converter-steel slag sampled from the steel plant of Shanxi Longmen Steel Group.In the plant, the steel slag was treated by water annealing then inside it numerous furniture developed.In the program,two successive series of experiments were conducted.For the first series, the annealed slag was crushed by means of jaw crusher and double-roll,resulting in granules with size less than 10.0mm.By means of sieving the granules were classified into four size grades:-10.0～+2.0mm,-2.0～+1.0mm,-1.0～+0.15mm,-0.15mm.Amagnetic separator of wet process was employed to separate the ferrous substance from the samples of the four grades described by applying various magnitude of magnetic flux density as shown on the machine panel.After the slag sample passed through the separator,the mass of refined powder and tailing slag were measured respectively.Then the quality(iron content) of the refined powder and tailing slag were determined by titration.Thus the iron recovery ratio was evaluated from the measurements.In order to perform the second series of experiments,the annealed slag was ground by ball mill of laboratory scale.Upon the dependence of the slag fineness and the grinding duration was achieved by experiments,the appropriate time for the slag fineness of 60%,70%, 80%and 90%were determined to be 17.3,22.7,29.2 and 37.8 seconds respectively.Samples with the specified fineness were prepared then were classified under the magnetic flux density of 0.14T(Wb/m~2).From the results it was recognized that the fineness of 60～80%was desirable for magnetic separation.Based on the results obtained the separation experiments by magnetic method had been carried out with four magnetic flux levels of 0.09T,0.115T,0.14T and 0.175T,and five fineness levels of the ground slag of 60%,65%,70%,75%and 80%.The results indicated that:The magnetic method of separation failed to result in the required effect of classification of the slag samples prepared only by crushing,for its insufficient isolation of ferrous particles from non-ferrous compounds.The converter-steel slag fines prepared by further grinding the preliminarily crushed samples were amenable to magnetic separation.With the powder fineness of 65%of mass passing through 200 mesh and the magnetic flux density of 0.175T,the magnetic method of separation resulted in refined powder with iron content up to 50.56%and iron recovery ratio up to 64.19%,available from the facilities used in the project.