Study On Dry Pre-Concentration Of Fine Ore And Technology Optimization Of Shaft Furnace Roasted Ore Of Specularite

Specularite is one of the important iron ore resources in China,because of its complex and diverse ore composition and fine particle size,at present,magnetizing roasting process of shaft furnace is adopted in JISCO.However,due to the difficulty in controlling the temperature field inside the shaft furnace and the large feed size,the roasting reduction of some iron ores is incomplete and the ore quality is not uniform,which leads to the loss of magnetic separation iron and the high grade of tailings iron.In this study,a spiral tube magnetic separator was introduced to pre-concentrate roasted ores by dry pre-concentration technology.Which can not only achieve better pre-concentration effect of roasted ores,but also reduce the distress of dewatering treatment in wet pre-concentrating.At the same time,it can optimize the separation process.The analysis of raw ore characteristics shows that the iron grade of the Specularite shaft furnace roasted ore is 37.85%,of which the main metallic mineral is magnetite;the main gangue mineral is quartz,and the distribution relationship between the two minerals is close and complex,and the distribution size is fine;the roasting reduction of some iron ore is incomplete,and the magnetic difference of iron ore is large,which makes the overall quality of roasted ore uneven.This is the main reason for the loss of magnetic separation iron in roasted ore and the high grade of tailings.It is necessary to carry out pre-concentration test of roasted ore and select some incomplete reduction iron ore for further treatment,so as to improve the quality of roasted ore.In this study,the helical tube magnetic separator was introduced for the first time to be used in dry pre-concentration of roasted ore,and its effect was compared with that of magnetic pulley dry pre-concentration.The significance of the pre-concentration effect of helical tube magnetic separator was analyzed,and the effect of feed size on the product index of dry separation was also investigated.Dry pre-concentration technology of fine ore was used to classify roasted ore into three products:?1?Dry concentrate with yield of74.41%,iron grade of 45.21%and recovery of 88.88%;?2?Dry middling with yield of18.03%,iron grade of 20.08%and recovery of 9.57%;?3?Dry tailings with yield of 7.56%,iron grade of 7.75%and recovery of 1.56%.Chemical iron phase analysis and grindability analysis show that the iron grade of dry concentrate is high,magnetic and grindable,and the iron grade of dry middling is high,magnetic weakness and hardness are high.Which shows that dry pre-concentration of roasted ore powder has remarkable effect.After dry preconcentration of fine ore of roasted ore,grinding and magnetic separation of dry concentrate and magnetic roasting-magnetic separation of dry middling,the final iron concentrate with total yield 54.75%,iron grade 58.43%and total recovery84.53%can be obtained,of which the SiO₂ content is 7.41%and the iron grade of tailings is 13.30%.Compared with direct grinding and magnetic separation of roasted ore,the iron recovery of concentrate increased by 7.02%,in which the SiO₂ content decreased by0.80%,and the iron grade of tailings decreased by 3.88%.Which shows that the dry pre-concentration process of roasted ore powder is effective and the separation process is optimized.A new idea is put forward for iron ore pre-concentration process.