| Crushing and grinding operations are the process of reducing ore particle size to provide qualified feed size for subsequent separation operations.The purpose is to dissociate the useful minerals monomer in the ores and avoid over crushing of material.Comminution process is an important part of concentrator.The quality of crushing and grinding products will directly affect the following beneficiation technical indicators.SAB process is adopted in a concentrator in a mining area.Recent industrial practices show that there are some problems in the crushing and grinding system,such as unstable ore-supplying property,mismatch of load between SAG mill and ball mill,over grinding of SAG mill products,which lead to poor production stability.Therefore,it is of great practical significance to study the SAG mill and ball mill system and optimize the comminution process.Aiming at four kinds of ore included the 24#ore body sample,13#ore body sample,SAG mill feed sample and pebble sample,this paper study ore properties,determine the comminution characteristic parameters and study ore comminution characteristics.JKSimMet simulation analysis was carried out using the comminution characteristics parameters obtained from the test and the field process investigation data.The study of ore properties by XRD and XRF shows that the ore is a complex polymetallic sulfide ore mainly composed of zinc,indium and tin.The main metal minerals in the ore are sphalerite,pyrrhotite,pyrite,magnetite,cassiterite,chalcopyrite,etc.The main gangue minerals are pyroxene,quartz,chlorite,calcite,hornblende,etc.The comminution characteristic parameters of ore were determined by Bond index test,JK drop weight impact crushing test and abrasion crushing test.The study of Bond index test shows that the 24#ore body sample Wib=15.25kWh/t,13#ore body sample Wib=14.28kWh/t,SAG mill feed sample Wib=16.81kWh/t,pebble sample Wib=19.69kWh/t.JK drop weight impact crushing test and abrasion crushing test show that the 24#ore body sample drop weight impact crushing test parameter A×b=56.92,abrasion crushing parameter ta=1.01;13#ore body sample A×b=153.51,ta=1.87;SAG mill feed sample A×b=55.76,ta=0.60;pebble sample A×b=29.35,ta=0.09.The analysis results of comminution properties of 4 kinds of ore samples shows that the impact crushing and abrasion crushing resistance of ore in 13#ore body are weaker than that of ore in 24#ore body,and the impact crushing resistance becomes weaker with the decrease of particle size.This ore is easy to crush in SAG mill,which affects the working efficiency of SAG mill and interferes with the grinding operation.The grinding effect of SAG mill can be improved by improving ore blending system or adding pre-screening.Compared with SAG mill feed sample,pebble sample has stronger impact crushing ability and abrasion crushing ability,and the crushing effect of pebble sample is not good at low specific crushing energy.In the abrasion crushing test,the recalcitrant can only break up on the surface,and the ore itself can not be effectively broken,which indicates that the pebble can not be effectively treated with low input energy.The energy and probability of crushing pebble by impact can be increased by increasing filling rate and diameter of steel balls in SAG mill.High energy crushing with crusher or high pressure roller mill is the most effective crushing method of pebble.According to the results of field process investigation,the actual production process of concentrator shows that the feed size is finer,the hydrocyclone overflow-0.074mm content is lower,and the pebble return is fewer,which results in the load mismatch between the SAG mill and the ball mill.The results of JKSimMet simulation test show that the sieving process can balance the load of SAG mill and ball mill.According to the field situation,increasing the sieving screening size can reduce the load of SAG mill and increase the load of ball mill.Without adding equipment,the sieve screening size will be increased from 10mm to 15mm,and the filling rate of steel ball of SAG mill will be adjusted by 9%,and the maximum diameter of steel ball in SAG mill is 140 mm.The simulated productivity can be increased from 350t/h to 415t/h.At this time,the load of SAG mill is 25.2%,and the power is 2464kW.The load fraction of ball mill is increased to 36%.When the grading size of cyclone(d50)is 0.12mm,the simulation index of 70.53%overflow-0.074 mm content can be obtained.The simulation conditions can obviously improve the grinding efficiency of existing grinding equipment on the premise of ensuring the stable production of concentrator.The research results of this paper can provide theoretical basis for the optimization of production in the concentrator,and provide reference for the optimization of comminution process in related concentrators using SAG comminution process.It has innovative and academic value. |
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