高铁赤泥中铝的赋存状态及铝铁分离技术研究

Chemical Occurrence State of Aluminum and a Novel Approach for Separation of Aluminum and Iron in High iron Bauxite Residue

针对拜耳法高铁赤泥无害化处置与资源化利用难题,研究了高铁赤泥中铝的赋存状态及其对铝铁分离的影响。借助XRD、铁化学物相分析、SEM-EDS等检测手段,研究了高铁赤泥的化学组成、矿物组成以及铝的赋存状态等工艺矿物学特征。查明赤泥的主要组成矿物为褐铁矿、赤铁矿、铝针铁矿和钛铁矿,其中铁主要以针铁矿、赤铁矿的形式存在;铝主要以类质同象存在于针铁矿中,形成铝针铁矿,部分以三水铝石的形式存在,铁铝共生关系密切。赋存于针铁矿中的铝采用常规物理分选方法无法实现铝铁分离,利用磁化焙烧和悬浮焙烧预还原—电炉熔炼工艺分别尝试对高铁赤泥进行铝铁分离,磁化焙烧能够实现赤铁矿、针铁矿向磁铁矿的定向转化,但不能有效破坏铁矿物中铝的类质同象结构,无法实现铝和铁的分离,导致磁选铁精矿中TFe品位低、Al2O3含量高;悬浮焙烧预还原—电炉熔炼工艺能有效实现高铁赤泥的铁铝分离与综合利用,当原料TFe品位为46.85%、Al2O3含量为13.31%时,可获得TFe 92.86%的炼钢用生铁,同时所得到的矿渣产品可以作为生产铝酸盐水泥熟料的原料。可见,悬浮焙烧预还原—电炉熔炼工艺可以有效破坏矿石内部铝和铁类质同象的晶格结构,实现了铝铁的高效分离,为高铁赤泥的无害化处置与资源化利用提供了新途径。

In order to solve the problem of harmless disposal and resource utilization of high iron bauxite residue(HIBR)from the Bayer process,the chemical occurrence state of aluminum in HIBR and its influence on aluminum-iron separation were studied.X-ray diffraction,chemical phase analysis,and scanning electron microscope were used to assess the characteristics of HIBR.The main focus is on the chemical composition,mineral composition,and occurrence status of aluminum in HIBR.The main constituent minerals of red mud are limonite,hematite,aluminum goethite,and ilmenite.The iron minerals are goethite and hematite,while aluminum mainly exists in goethite with isomorphism,forming aluminum goethite,and partly exists in the form of gibbsite,thus the mineral paragenesis is complex and close.The conventional physical separation methods cannot achieve the separation of aluminum and iron in goethite,and the magnetization roasting and suspension roasting pre reduction electric furnace smelting processes are used to attempt to separate aluminum and iron from the red mud.The hematite and goethite in the red mud were successfully transformed into magnetite during magnetization roasting,but the isomorphic substitution structure of aluminum in iron minerals could not be destroyed,unable to separate aluminum and iron,leading to a low TFe grade and high Al2O3 content in the magnetic concentrate.However,suspension roasting pre-reduction followed by electrical furnace process(SRPEF)can effectively realize the removal of aluminum and comprehensive utilization of HIBR.A pig iron bearing 92.86%TFe and non-hazardous slag can be obtained by processing a HIBR with 46.85%TFe and 13.31%Al2O3.The pig iron can be used as raw material for steel making,and slag can be used as clinker for the production of aluminate cement.It can be seen that the suspension roasting pre reduction electric furnace smelting process can effectively destroy the lattice structure of aluminum and iron like substances in the ore,achieve efficient separation of aluminum and iron,and provide a new way for the harmless disposal and resource utilization of high iron bauxite residue.