Reduction consumption of binder by modified bentonite in high proportion sulfuric acid slag pellets
To solve the problem of high binder dosage and poor quality of pellets with a high proportion of sulfuric acid slag pellets,research on the quality improvement and modification of low-quality calcium-based bentonite was carried out to reduce the binder dosage and increase the proportion of sulfuric acid slag.After adding 1.5％organic binder OA based on calcium-based bentonite,the modified bentonite was obtained by a high-pressure extrusion of organic interlayer modification.The results show that with the binder dosage of 1.2％as the basis,the proportion of mixed ore sulfate slag is 50％,the properties of pellets prepared with modified bentonite are significantly im-proved compared with those prepared with unmodified calcium bentonite,including the raw ball drop strength in-creases from 1.2 times(0.5 m)to 4.8 times(0.5 m),and the baked ball strength increases from 1 095 N/P to 2 721 N/P.The crystal layer spacing of the modified bentonite is reduced from d1(001)=1.529 7 nm to d4(001)=1.190 6 nm for calcium-based bentonite,indicating that the organic modification effect is sufficient.The characteris-tic peaks of Si—O—Si,MgAl—OH,H—O—H,COO—,and NH4+are enhanced,which improves the water-hold-ing capacity of raw material and the plastic deformation performance of the pellet,and the maximum capillary water increases from 23.8％to 27.0％.In addition,the organic components in the modified bentonite are volatilized by heat,forming pores between the bentonite crystal layers,which is conducive to diffusing of oxygen to the interior of pellet and the surface of mineral grains and fully oxidizing and solidifying,so that the internal structure of the pellet is more compact,which improves the strength of the pellet.The result can provide theoretical guidance and practical basis for the upgrading and modifying of low-quality bentonite and the industrial application of high-ratio sulfuric acid slag pellets.
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