Concretion properties of organic-binder oxidate pellets and strengthen measures

The mineral composition and the structure of two kinds of pellets made by bentonite and organic binder respectively were studied and the mechanisms of these two kinds of binders in the palletizing process were compared. The results show that the strength of organic-binder pellets is lower than that of bentonite pellets. One reason is that particles in organic-binder pellets contact looser and the porosity is higher. The other is that the content of low-melting material in organic-binder pellets which plays the role of bonding is less than that in bentonite pellets. The contact of particles in organic-binder pellets can be improved by reducing the size of iron concentrate using ball milling and the damp milling. The strength of preheated pellet increases from 159 N to 488 N, and that of indurated pellets increases from 1 405 N to 2 534 N in the condition of preheating for 10 min at 950 ℃ and indurating for 10 min at 1 250 ℃. Furthermore, the forming of low-melting material in organic-binder pellets can be improved and the strength of preheated pellets increases from 245 N to 426 N, and that of indurated pellets from 1 477 N to 3 051 N by adding 1.25% limestone to pellets in the condition of preheating for 10 min at 1 010 ℃ and indurating for 10 min at 1 250 ℃.