Application Technology Of Stirred Mill In Iron Ore Regrinding System

As a fine and superfine grinding equipment,stirred mill possesses the characters of large capacity,small particle size,low power consumption,etc.After decades of research,it has been developed as Metso,Eirich and other large stirred mill.Especially in the last 20 years,the heat of studying stirred mill increases at home and abroad.Stirred mill is applied in non-ferrous metal ore more frequently and iron ore concentrator begins to apply it as fine grinding equipment.Dagushan pellet plant is the first large-scale iron ore concentrator of China which has been constructed completely.Currently,the pellet plant process is longer and the stability is poor.With the depth of the decline in mining,mineral composition is changing.Regrinding system with less new monomer dissociation ore and large sand back exists problems of low mill utilization factor,high regrinding cost and so on.This article based on the particle size character of regrinding ore at Dagushan pellet plant,conducts systematic grinding test of stirred mill and compared with ball mill to explore the feasibility of stirred mill substitute ball mill in regrinding system at Dagushan pellet plant.In this paper,process mineralogy character of regrinding ore at Dagushan pellet plant was researched.It shows that the total iron grade is 55.56%,mainly existing in the form of magnetite,in which the content of iron is as high as 54.40%.Disseminated particle sizes of the ore is fine,of which 34.12 percent of magnetite distributes in-0.038mm grain size.The monomer dissociation degree of iron is low.Intergrowth content is 30.50%and magnetite in the form of poverty intergrowth is mainly packaged in gangue minerals.In order to investigate the influence law of the effect of stirred mill grinding,this paper studies the grinding medium,ball percentage,medium charge ratio,mill speed,grinding concentration stematically.Determine the appropriate process conditions such as grinding media is 8 mm steel ball,ball percentage is 0.8,medium charge ratio is 75%,mill speed is 300 r/min,grinding concentration is 68.5%.Similarly,it determine the ball mill grinding parameters such as ball diameter ratio is 5:3:2,medium charge ratio is 33.22%,ball percentage is 1.0,grinding concentration is 68.5%.Compared the grinding efficiency of stirred mill and ball mill,the content of-0.038mm is higher 25.37 points than ball mill when the same energy is consumed.In this case,magnetic concentrate grade is higher 7.15 percentage points than ball mill's and the grinding efficiency of stirred mill is significantly higher than ball mill's.In this paper,the effects of two kinds of grinding mill are analyzed.Determine the quantitative relation between specific production rate and grinding fineness as follows:Stirred mill's is q = 10.37-0.107? and ball mill's is q = 13.96/1.08?.The specific production of stirred mill is linear decline with the finer of granularity into the mill but the ball mill's is exponential decline.It can be seen clearly that the particle size of ore is finer,the grinding effect of stirred mill is better than ball mill's.The relationship between energy consumption of mills and grinding fineness are dE =-cdx/x2.2 and dE =-cdx/x3.91.The finer the particle size of ore,the better the effect of energy saving of stirred mill is.Analyse the main mode of action of the force and illustrate the main reason of stirred mill save energy than ball mill on the angle of the medium stress.It provides the basis for the optimization of the structure of stirred mill.