發(fā)布時間：2018-06-09 20:51

  本文選題：海濱鈦磁鐵礦 + 直接還原-磁選　； 參考：《北京科技大學(xué)》2017年博士論文

【摘要】：海濱鈦磁鐵礦儲量豐富,采選成本低廉,但用常規(guī)的選礦方法得到的鐵精礦中鐵品位低、TiO_2含量高,冶煉難度大,并且鈦進入了高爐渣,導(dǎo)致鈦資源的浪費。研究表明,內(nèi)配煤直接還原-磁選工藝可以實現(xiàn)鈦磁鐵礦中鈦、鐵的有效分離,但煤中所含的灰分會進入到非磁性產(chǎn)品(即鈦產(chǎn)品)中,導(dǎo)致鈦產(chǎn)品中的TiO_2品位低,未實現(xiàn)鈦的有效富集。因此,本論文采用包埋法直接還原-磁選工藝,即只將海濱鈦磁鐵礦壓成球,煤不與鈦磁鐵礦混合,而是包埋在球團的周圍進行直接還原焙燒,目的是實現(xiàn)鐵和鈦的同時回收。以鐵品位57.29%、TiO_2品位11.42%的印尼某海濱鈦磁鐵礦弱磁選精礦為試樣,系統(tǒng)研究了包埋法直接還原-磁選鈦鐵分離工藝及機理�？疾炝颂砑觿┓N類及用量、還原劑種類及用量、還原時間和溫度等對包埋法直接還原-磁選鈦鐵分離并分別富集效果的影響。結(jié)果表明,無論加入硫酸鈉或螢石,還原鐵產(chǎn)品鐵回收率和鈦產(chǎn)品TiO_2品位均較低,不能達到目標要求。還原劑影響鈦鐵分離效果,煙煤為還原劑得到的還原鐵產(chǎn)品和鈦產(chǎn)品的各指標較無煙煤和焦炭的好。延長還原時間能夠提高還原鐵產(chǎn)品中的鐵品位和鐵回收率,以及鈦產(chǎn)品中的TiO_2品位。在最佳工藝條件下,得到了鐵品位為90.48%、鐵回收率為90.12%、TiO_2含量為0.93%的還原鐵產(chǎn)品和TiO_2品位為45.58%、TiO_2回收率為95.35%的鈦產(chǎn)品,實現(xiàn)了鈦鐵分離并分別富集。采用X射線粉晶衍射、掃描電鏡、能譜分析和煙氣分析等方法進行了機理研究。研究表明,加入添加劑硫酸鈉或螢石不僅引入雜質(zhì),而且對鈦磁鐵礦的還原不利。包埋法的還原效果取決于還原劑反應(yīng)性,氣化反應(yīng)性好的還原劑還原效果更好。原因是反應(yīng)性好的煙煤,較低溫度下能夠提供更強的還原氣氛,抑制鐵橄欖石的生成;而反應(yīng)性差的無煙煤和焦炭則相反,最終導(dǎo)致鐵橄欖石的生成,不僅降低鐵回收率,還促進液相產(chǎn)生,不利于還原氣體擴散,抑制了還原反應(yīng)的進行。通過對還原時間和溫度的研究,確定了含有Mg類質(zhì)同象的鈦磁鐵礦還原歷程為Fe_2(Mg,Fe)_(0.75)Ti_(0.25)O_4→(Fe,Mg)_2TiO_4→(Fe,Mg)TiO_3→(Fe,Mg)Ti_2O_5→MgTi_2O_5+Ti_3O_5。
[Abstract]:Seaside titanomagnetite is rich in reserves and low in cost of mining and dressing. However, the iron concentrate obtained by conventional dressing method has high iron grade and high content of TiO-2, and it is difficult to smelt, and titanium enters into blast furnace slag, which leads to the waste of titanium resources. The results show that the direct reduction and magnetic separation process can effectively separate titanium and iron from titanomagnetite, but the ash contained in the coal will enter into non-magnetic products (i.e. titanium products), resulting in the low grade of TiO2 in titanium products. The effective enrichment of titanium was not realized. Therefore, in this paper, the direct reduction-magnetic separation process is adopted, that is, only the beachfront titanomagnetite is pressed into a ball, the coal is not mixed with the titanomagnetite, but is buried around the pellet for direct reduction roasting, in order to realize the simultaneous recovery of iron and titanium. The separation process and mechanism of titanium-iron by direct reduction magnetic separation were systematically studied with a weak magnetic concentrate of a seaside titanomagnetite in Indonesia with iron grade 57.29 and TiO-2 grade 11.42%. The effects of additives, amount of additives, reduction time and temperature on the separation and enrichment of iron titanate by direct reduction and magnetic separation were investigated. The results show that the iron recovery rate of iron products and the TiO-2 grade of titanium products are lower than those of titanium products, and can not meet the requirements of the target, regardless of the addition of sodium sulfate or fluorite. Reducing agent affects the separation effect of iron and titanium. Bituminous coal is better than anthracite and coke in each index of reducing iron product and titanium product. Prolonging the reduction time can improve the iron grade and iron recovery rate in the reductive iron product and the tio _ 2 grade in the titanium product. Under the optimum technological conditions, the products with iron grade 90.48, iron recovery 90.12% TiO2 0.93% and TiO2 45.58% TiO2 recovery 95.35% were obtained. The mechanism was studied by means of X-ray powder diffraction, scanning electron microscope, energy spectrum analysis and flue gas analysis. The results show that the addition of sodium sulfate or fluorite is not only impurity, but also disadvantageous to the reduction of titanomagnetite. The reduction effect of the entrapped method depends on the reactivity of the reductant, and the reduction effect of the reductant with good gasification reactivity is better. The reason is that the bituminous coal with good reactivity can provide a stronger atmosphere of reduction and inhibit the formation of iron olivine at lower temperature, whereas the unreactive anthracite and coke, on the contrary, lead to the formation of iron olivine, which not only reduces the recovery rate of iron, but also decreases the rate of iron recovery. It also promotes the production of liquid phase, which is unfavorable to the diffusion of reducing gas and inhibits the process of reduction reaction. Based on the study of reduction time and temperature, the reduction process of magnetite containing mg type magnetite is determined to be: the reduction process of Fe2MgTi2O5 MgTi2O5 Ti3O5 structure is as follows: titio 0.75TiO4 titio 0.25TiO4 tio 0.75TiO4 titio 0.75 tio _ 2tio _ 4 titio _ (0.75) tio _ (2tio) tio _ (5) tio _ (tio _ 2O _ 5).
【學(xué)位授予單位】：北京科技大學(xué)
【學(xué)位級別】：博士
【學(xué)位授予年份】：2017
【分類號】：TD951

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