Study On The Behavior And Experiment Of Gelatinized Starch In Iron Oxide Pellets

High quality adhesive is an important prerequisite for the production of high quality pellets.Bentonite is used to make the pellet,and the high melting point of the refractory oxide will directly reduce the iron content of pellets.However,the organic binder can ensure the premise of pellet strength decrease of pellets and containing iron grade.The functional groups contained in the binder can not only improve the contact angle between the iron concentrate particles,but also improve the wetting properties.Increasing the number of polar groups can not only improve the ballability of iron materials,but also improve the pellet strength.The gelatinized starch had more exposed organic functional groups,and after the gelatinization of starch,the structure is looser and easier to water swelling,viscosity becomes stronger and it also have a strong adsorption capacity on the surface of iron ore particles.The gelatinized starch as the research object,the effect of extruded starch on the strength,bursting temperature,the strength of the finished ball as well as the effect of extruded starch on the pellet was studied,the theoretica basis is provided for the application of gelatinized starch in pellets.In the study of gelatinized starch,it was found that the number of carboxyl and hydroxyl groups of gelatinized starch was much more than that of common starch.Under high temperature conditions,the gelatinized starch reacts with oxygen in the air to form CO₂ and H2 O,and the residue is only 2% of the initial weight.Making the pellet with gelatinized starch can made the ball's surface smoother,puffing of starch in the ball inside will produce a gelatinous substance and promote the bond between the iron ore concentrate pellets and water,pellet density and intensity are also improved.CO₂ and water from the pellet can increase the porosity of the gelatinized starch pellet in the process of pellet roasting,which leads to the decrease of the strength of the finished pellet,but the reduction ability of pellets is enhanced.When the ratio of binders is 2%,falling strength and compressive strength of bentonite pellet respectively 4.8 times/p and 14.1N/p,and the gelatinized starch pellet can reach 11.3 times/p and 17.6N/p.The 0.3% gelatinized starch and 0.7% bentonie as the compensate binder were used for pelletizing tests.the drop strength of pellet is 6.7 times/p,the compression strength of 13.1 N/p and the bursting temperature is 546?,the compressive strength of the pellet product is 2466 N/p.Meet the pellet quality requirements of blast furnace.The pellets made by bentonite or the mass fraction of 0.7% bentonite and 0.3% gelatinized starch were tested for metallurgical properties,the metallurgical properties of the composite binder pellets are better than that of bentonite pellets.The RI in composite binder pellets was 60.1%,which was higher than 57.2% of bentonite pellets in the same strength.The reduction coefficient of expansion is also low with bentonite pellets of 16.64%.The softening range is decreased from 160? to 92?,which is helpful to improve the permeability and permeability of the soft melt zone,it also has a positive effect on reducing the internal pressure of the blast furnace and increasing the yield.