Research And Practice Of Improving Quality And Reducing Consumption Of Vanadium Titanium Magnetite Oxide Pellet

ABSTRACT:Characterized as coarse particle size, small specific surface area and high difficulty of oxidation, vanadium titanium magnetite concentrate requires high bentonite dosage, long preheating time and narrow roasting temperature interval when it is used to produce iron ore pellets using grate-kiln. These operation requirements mainly contribute to the low grade of iron ore pellets, poor pellet strength, high energy consumption and possible ring formation in rotary kiln.The main raw material in this study is from Panzhihua palletizing plant. Based on the systematic analysis on the characteristics of oxidized pellets prepared from vanadium titanium magnetite concentrate, this paper attempts to improve pellet quality by pretreatment of raw material combined with composite binder. Based on oxidation dynamics of vanadium titanium magnetite and field production practice on lifting kiln lining life, this paper looks into the rationale of series of problems mentioned above and develops relative processing technology on improving the pellet quality, reducing production energy and extending kiln lining life.Results of raw materials pretreatment showed that both high-pressure roller milling and wet grinding improves particle size and specific surface area of the concentrate. Comparatively, high-pressure roller milling possesses a larger capacity for throughput and a higher efficiency with less power consumption. The suitable process parameters of high-pressure roller milling were identified as7.5%of raw materials moisture content,8MPa of roller pressure. At these parameters, the specific surface area of the material roll mill has improved by331cm2/g, ball rate increased5.48%, the green ball quality improved obviously.Effect of binder type and binder dosage was studied and results showed that the grade of iron ore pellet has improved by1.05%when0.5%composite binder was added compare with using2%bentenite. And pellet quality meet the production requirements.On the basis of the systematic study on vanadium titanium magnetite oxidation kinetics, series of technical measures have been proposed, which includes the optimizing thermal operation of the grate-rotary kiln, improving equipment capability of successive and stable production, optimizing the green pellet size distribution. These measures were successfully applied in practical production, roasting temperature has decreased from1300℃to1180℃, and energy consumption of roasting process has decreased by10.22kgce/t, meanwhile the ore consumption has been reduced and maintenance cost has been reduced.Main influential factors on kiln lining life were systematically analyzed, rotary kiln lining service life has increased from one year to three years and Production maintenance time in half by adopting series of measures comprising the optimizing the roasting operation, adjusting the primary air flow, improving the kiln lining material, precasting the brick structure and improving the kiln construction.Series of technologies on improving pellet quality and reducing energy consumption in producing iron ore pellets from vanadium titanium magnetite concentrate were integrated and applied in production practice. Good result has been obtained and a single production line of the grate-kiln (1.2million tons per year) has created economic benefit of20.1841million yuan.