某贫磁-赤混合铁矿石预选工艺研究

Study on the Preconcentration Process of a Lean Magnetic Hematite Ore

某贫磁-赤混合铁矿石铁品位低,目前原矿破碎后直接入磨选,采用阶段磨矿-弱磁-强磁-阴离子反浮选工艺流程,生产成本居高不下。为降低磨矿能耗,在实验室进行了破碎产品(-12 mm)筒式中磁-辊式强磁干式预选试验、破碎产品(-12 mm)湿式外磁内筒式磁选机预选试验、超细碎产品(-3 mm)-粗粒湿式中磁-脉动高梯度强磁预选工艺对比试验。结果表明:采用超细碎-粗粒湿式中磁-脉动高梯度强磁预选工艺选别指标最好,在超细碎产品粒度-3 mm、中磁选磁场强度318 kA/m、强磁选磁场强度955 kA/m的条件下,可抛除产率25.19%、铁品位6.46%、铁损失率仅5.42%的合格尾矿,预选精矿铁品位较原矿提高了7.93个百分点,为37.92%,预选抛尾效果十分显著,可为赤铁矿石或混合铁矿石的预选工艺提供有益借鉴。

The iron grade of a lean magnetic-hematite ore is low. At present,the raw ore is directly put into grinding and separation after crushing,and the production cost remains high with the process of stage grinding,low intensity magnetic separation,high intensity magnetic separation and anion reverse flotation. In order to reduce the energy consumption of grinding,in the laboratory,the crushed product(-12 mm)cylindrical magnetic-roller high intensity dry magnetic pre-separation test,crushed product(-12 mm)wet external magnetic inner cylinder magnetic separator pre-separation test,ultra-fine crushed product(-3 mm)-coarse-grained wet-mode magnetic-pulsation high-gradient high intensity magnetic pre-separation process comparison test. The results showed that,the separation index of ultra-fine fragmentation-coarse particle wet medium magnetic-pulsating high gradient high intensity magnetic preseparation process is the best. Under the conditions of ultra-fine product granularity(-3 mm),medium magnetic separation magnetic field intensity 318 kA/m,and high intensity magnetic separation magnetic field intensity 955 kA/m,qualified tailings with productivity of 25.19%,iron grade of 6.46% and loss rate of only5.42% can be removed. Compared with the raw ore,the irong rade of pre-concentrate was increased by 7.93 percentage points to 37.92%,the effect of pre-separation is very obvious,which can provide useful reference for the pre-separation process of hematite or mixed iron ore.