| Iron ore pellet has many advantages as one kind of burden for iron making, such as better metallurgical properties and obviously improving the permeability of the burden bed in the blast furnace. It is regrarded as an essential and excellent charge for optimizing the furnace structure, and widely used in iron and steel industry. In recent years, most of steel companies in China are developing pellet production at a higher rate, specially grate-kiln pellet production technology. At present, bentonite as one kind of binder is used in many pellet plants. However, many residues are obviously left in the pellets after they are fired, which decreased TFe of the roasted pellet decreased. Therefore, developing new binders to substitute bentonite or decrease the bentonite dosage is an effective way to improve TFe of the roasted pellets.In this research, it was tried to derease bentonite dosage and increase TFe of pellets by using organic binder'D(carboxyl methlated amylum after modified) and F partially or completely to substitute bentonite, which is done on the base of maintaining green ball properties at the required level. The experiments result of making pellets by adding single binder showed that the effect of that bentonite was substituted by 2.0% F or 0.25%～0.3% D was equivalent to that of 1.0% bentonite on green ball strength, heat stability et al. The experiment result of making pellets by adding mixture of binders showed the the composite binder with 0.5% bentonite and 0.1% D was a better choice relatively, by using which it could obtain a good result, drop strength was 3.3 per 0.5m and burst temperature was over 600℃, which decreased the dosage of bentonite and increased green ball drop strength and burst temperature, comparing with the experiments result of green ball making by adding 1.0% bentonite.The results of preheating-roasting experiments of the pellets added organic binder D and composite bentonite and D showed that strength of roasted pellet by adding 0.3% D was 2946N/p, however, the compression strength of preheated pellet was very low, only 150N/p, which couldn't meet the requirements for grate-kiln pellet production technology. For the pellets with the mixture 0.1% of D and 0.5% bentonite, the preheated pellet strength of over 400N/p and roasted pellet strength of 2600N/p～2900N/p were obtained. The TFe of pellet was significantly increased by using .organic binder D either fully or partially as a substitute for bentonite. The TFe reached 64.07% when 0.3% binder D only was added in the pellet, and 63.74% when 0.1% organic binder D and 0.5% bentonite. The two TFe contents were 0.76% and 0.43% which were higher than that with 0.1% bentonite, respectively.The magnetic concentrate pellets have good characteristic of absorbing microwave. Microwave heating processing was used to solve the problem of low preheated pellets strength with single organic binder D. It was shown that the preheated pellet strength was 129N/p when the pellet was preheated at 750℃for 10min under traditional conditions, and it was only 170N/p at 900℃. While the preheated pellets strength was improved widely by microwave heating, the preheated pellet strength was 448N/p when the microwave input power was 2500W and the microwave heating terminal temperature was 750℃, the preheated pellet strength was l155N/p at 900℃.Microwave heating has the characteristic of intemal heating, so it could have effect on the whole materials and the materials were heated evenly. By the application of optical microscope, XRD and SEM, the oxidized mechanism of preheated pellets with organic binder D was performed, the result showed that magetites of intemal pellet after traditional heating were partly oxidized into hematites, and its microcrystallite were connected a little, the whole structure of pellet was unconsolidated, so the strength of preheated pellet was bad. After microwave heating, majority magnetites were oxidized into hematites which were connected with each other, and the intemal mineral structure of pellet was compact and homogeneous, So the preheated pellets have high strength.
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