Regularities of high-pressure roll grinding strengthening for high-quality pellets preparation from coarse iron ore powder
Utilizing coarse iron ore powder to replace a portion of concentrate in the preparation of oxidized pellets can reduce raw material costs.However,coarse iron ore powder has a high content of coarse particles,poor balla-bility and roasting property,resulting in low pellet strength and making it challenging for large-scale incorporation.The influence of high-pressure roll grinding(HPRG)pretreatment on the preparation of oxidized pellets using coarse iron ore powder was investigates.The results indicate a significant decrease in particle size larger than 1 mm in the coarse iron ore powder after HPRG pretreatment.Concurrently,the fine particle content increases,and the specific surface area enlarges.Compared to increasing roller pressure intensity,a higher number of grinding passes prove more beneficial for coarse particle fragmentation.Additionally,the appropriate feed moisture for coarse iron ore powder is relatively low.HPRG pretreatment can enhance particle surface properties,improve the hydrophilicity and ballability of coarse iron ore powder,consequently enhancing green pellets quality.Moreover,under mechanical force,iron-bearing minerals undergo crystal activation.When the roller pressure intensity is increased to 12 MPa or more,the mechanical activation effect is strengthened,facilitating solid-phase reactions between particles and thus enhancing pellets strength.Using coarse iron ore powder with the particle size less than 1 mm for pellets experi-ments,compared to untreated coarse iron ore powder,after roller pressure intensity at 14 MPa,with a feed mois-ture of 3.5％,and two open-circuit HPRG pretreatment,the ratio of coarse iron ore powder in pellets can be in-creased from 15％to 30％under the same preparation process,and the roasting pellets compressive strength can in-crease by 589 N/P(Newton per pellet)when maintaining a coarse iron ore powder ratio of 15％.The research find-ings provide theoretical and technical guidance for diversifying pellet raw materials and reducing the pretreatment en-ergy consumption and pellet production costs.
coarse iron ore powderhigh-pressure roll grindingmechanical activationoxidized pelletcompressive strength
NETL
NSTL
万方数据
