Pelletization is one of the methods of converting iron concentrate particles into a dense mass. The quality of raw pellets is very important because pellets are the final product of the pelletizing process and the raw material for the raw iron production process. In this research, using linear and multivariate regression methods and correlation test with the help of SPSS data analysis application software and experiment design with the help of Design Expert software, the effective parameters on the quality of raw pellets were examined. The required data, the production parameters were eva‎luated during 15 months of the production of disks in the pelletizing unit of Isfahan Mobarakeh Steel Company. In this way, four parameters affecting the quality of raw pellets and four quality indicators of raw pellets were used in the pelletizing disc. The parameters affecting the quality include the granulation distribution of the iron ore concentrate, the specific surface area of the concentrate, moisture and the bentonite used as an adhesive, and the qualitative indicators that include dry compressive strength, more compressive strength, the number of drops and the return rate of pellets from discs. In this period of time, the data that have had unusual changes due to emergency and planned stops have been removed. Also, the parameter values that are more than one data per day are considered average. The impact of each input parameter on the output parameters is checked separately to determine the optimal value of the test design method. In general, data analysis was obtained by multivariate regression method and the correlation coefficient of a linear model for a parameter with greater intensity in each disc. The results showed that increasing the percentage of bentonite due to the excessive adhesion of micro pellets and primary sprouts has an effect on increasing the return rate of raw pellets. Moisture and dry compressive strength have a significant relationship so that the uniform distribution of moisture in the presence of bentonite glue prevents cracking and increases the dry compressive strength when the raw pellet dries. Also, by increasing the ratio of milled materials to soft materials, in fact, the particles become finer, the capillary tubes are more, the surface tension is higher and finally the compressive strength is increased. In the significant relationship between the specific surface area and the falling number, the specific surface area increases with the increase in viscous forces caused by the presence of liquid glue, which increases the connection points between the particles and the falling number increases. The connection of liquid glue and the result of increasing the number of falls. In raw pellets, the increase in humidity to about 9% will increase the plasticity of the raw pellets and lead to an increase in the number of drops in the pelletizing discs.

مهدي علي زاده

مريم كرباسي , مهدي احمديان