本文選題：流化床 + 鐵礦粉��； 參考：《中國科學(xué)院大學(xué)(中國科學(xué)院過程工程研究所)》2017年博士論文

【摘要】：流態(tài)化氣基還原煉鐵直接以粉礦為原料,省去了球團(tuán)、燒結(jié)和煉焦等工序,是一種很有發(fā)展前景的直接還原煉鐵技術(shù)。隨著優(yōu)質(zhì)鐵礦資源的減少,選礦后得到的礦粉中細(xì)粉(粒度在100 μm左右)含量越來越高。這些細(xì)粉具有較高的還原速率,可以充分發(fā)揮流態(tài)化煉鐵技術(shù)的優(yōu)勢(shì),然而其在高溫氣基流化還原過程中,由于顆粒表面粘性增大或者鐵晶須的生成較易發(fā)生粘結(jié)并形成大聚團(tuán),繼而導(dǎo)致整個(gè)床層的失流,會(huì)對(duì)穩(wěn)定生產(chǎn)造成嚴(yán)重影響。針對(duì)這一問題,本文以鐵礦粉在不同多級(jí)流化還原工藝中出現(xiàn)的中間產(chǎn)物(如低金屬化率顆粒、Fe3O4、FeO和富碳顆粒等)為研究對(duì)象,通過模擬工業(yè)上的多級(jí)流化還原系統(tǒng),提出了一系列高效的抑制粘結(jié)失流方法,并對(duì)其作用機(jī)制進(jìn)行了深入研究。本文所取得的主要研究成果如下:揭示了還原條件對(duì)多級(jí)流化還原預(yù)還原段低金屬化率顆粒表面鐵析出形貌及其粘結(jié)行為的影響規(guī)律,提出了調(diào)控鐵析出形貌抑制鐵礦粉多級(jí)流化還原粘結(jié)失流的操控方法。研究表明在CO中混入H2可以加快鐵晶粒的生長速率,同時(shí)增加還原初期礦粉表面的鐵形核數(shù)量,導(dǎo)致礦粉表面新生成的金屬鐵由晶須狀轉(zhuǎn)變?yōu)橹旅軤�。隨著CO-CO2中CO2含量的升高,礦粉表面新生成的金屬鐵會(huì)由"鋒利"的晶須狀轉(zhuǎn)變?yōu)?仙人掌狀",并且表面鐵的分布密度會(huì)變小。隨著還原溫度的降低,礦粉表面鐵晶須的強(qiáng)度會(huì)變?nèi)酢＿@些均可以顯著減少低金屬化率顆粒流化還原過程中形成的聚團(tuán)量。此外,在預(yù)還原段將低金屬化率顆粒表面的鐵析出形貌由晶須狀轉(zhuǎn)變?yōu)橹旅軤?可以有效降低防止深還原段高金屬化率顆粒失流的MgO加入量。揭示了 MgO對(duì)多級(jí)流化還原過程中不同價(jià)態(tài)鐵氧化物礦粉粘結(jié)失流的抑制機(jī)制,提出了添加MgO抑制鐵礦粉多級(jí)流化還原粘結(jié)失流的較優(yōu)加入時(shí)段。MgO與不同價(jià)態(tài)鐵氧化物間的界面反應(yīng)行為表明,在中低溫(700和800 ℃)下MgO對(duì)Fe2O3、Fe3O4和FeO礦粉粘結(jié)失流的抑制作用主要是物理阻隔效應(yīng)。在高溫(900 ℃)下對(duì)于主要成分為Fe2O3的礦粉來說,物理阻隔效應(yīng)依然是主要抑制作用;對(duì)于主要成分為Fe3O4和FeO的礦粉來說,化學(xué)反應(yīng)形成的阻隔層是抑制粘結(jié)失流的主要原因,并且MgO在FeO礦粉表面形成的化學(xué)阻隔層厚度大于其在Fe3O4礦粉表面形成的�；瘜W(xué)阻隔層比物理粘附引起的抑制作用更加有效。因此在Fe3O4和FeO穩(wěn)定存在的多級(jí)流化還原工藝中,加入MgO對(duì)高溫下粘結(jié)失流的抑制效果由強(qiáng)到弱可按如下順序排列:FeOFe3O4Fe2O3。還原實(shí)驗(yàn)結(jié)果表明加入MgO抑制粘結(jié)失流對(duì)鐵礦粉還原速率的影響較小。制備新型添加劑CaO/Fe2O3強(qiáng)化了鈣組分對(duì)鐵礦粉流化還原過程中粘結(jié)失流的抑制效果,并揭示了其抑制機(jī)制。研究表明分析純CaO粉末和Ca(NO3)2·4H20分解產(chǎn)生的CaO對(duì)粘結(jié)失流的抑制作用較弱,而Fe(NO3)3·9H20和Ca(NO3)2·4H20混合物分解產(chǎn)生的CaO/Fe2O3具有較好的抑制效果。CaO/Fe2O3的還原結(jié)果表明Ca組分主要通過物理阻隔效應(yīng)抑制粘結(jié)失流。微觀組織結(jié)構(gòu)觀察表明CaO/Fe2O3不僅可以抑制"鋒利"尖狀鐵的生成,還可以使Ca組分緊密地包覆在粘性鐵表面,從而降低其表面粘性。此外,研究表明引入Fe2O3強(qiáng)化性能較差添加劑對(duì)粘結(jié)失流的抑制效果具有普適性。揭示了鐵礦粉多級(jí)流化還原過程中的碳沉積和演變行為,發(fā)現(xiàn)沉積碳不僅是還原過程中礦粉顆粒粘結(jié)的抑制劑,還是性能優(yōu)越的固相還原劑。高還原勢(shì)、低溫及H2的引入可以加速多級(jí)流化還原預(yù)還原段碳的沉積,尤其是石墨型游離碳的沉積。石墨型游離碳可以抑制鐵晶須生成,降低顆粒表面粘性,從而防止礦粉顆粒在高溫深還原中發(fā)生粘結(jié)。高溫深還原中石墨型游離碳和碳化鐵均會(huì)通過氣化反應(yīng)和固相還原反應(yīng)被消耗,并且石墨型游離碳的反應(yīng)活性高于碳化鐵。為了強(qiáng)化流態(tài)化技術(shù)在直接還原煉鐵中的應(yīng)用,提出了利用高活性沉積碳通過固固反應(yīng)將鐵礦粉還原至較高金屬化率的方法,并且證明了它的可行性。綜上所述,本文圍繞抑制鐵礦粉多級(jí)流化還原粘結(jié)失流展開,基于鐵礦粉在不同工藝中的演變特性,提出了一系列高效的操控方法,如調(diào)控鐵析出形貌抑制多級(jí)流化還原預(yù)還原段低金屬化率顆粒的粘結(jié),同時(shí)減少防止深還原段高金屬化率顆粒失流的MgO加入量;在多級(jí)流化還原的FeO段加入MgO,利用高溫下固固反應(yīng)形成的化學(xué)阻隔層高效地抑制粘結(jié)失流;制備新型抑制粘結(jié)失流添加劑CaO/Fe2O3,強(qiáng)化Ca組分對(duì)粘結(jié)失流的抑制效果。此外,在深入分析鐵礦粉多級(jí)流化還原中碳沉積和演變行為的基礎(chǔ)上,提出了直接利用沉積碳進(jìn)行高溫深還原的方法。與前人研究相比,本文所提出的抑制方法更加貼近實(shí)際工業(yè)過程,更具針對(duì)性和高效性,可操作性強(qiáng)。
[Abstract]:The fluidized gas based reduction ironmaking directly takes powder ore as the raw material, and saves the pelletizing, sintering and coking processes. It is a very promising direct reduction iron smelting technology. With the reduction of high quality iron ore resources, the fine powder in the ore powder (the grain size is about 100 m) is getting higher and higher after the mineral resources. These fine powders have high reduction rate. It can give full play to the advantages of fluidized iron smelting technology. However, in the process of high temperature gas based fluidized reduction, it can cause the loss of the whole bed because of the increase of the viscosity of the particle surface or the formation of the ferric whisker, which will lead to the severe effect on the stable production. In this paper, the iron ore powder is used in this paper. The intermediate products (such as low metal rate particles, Fe3O4, FeO and carbon rich particles) in different multistage fluidized reduction processes are studied. A series of efficient methods for inhibiting bond loss are proposed by simulating the multistage fluidized reduction system in the industry, and the mechanism of its action is deeply studied. The main research obtained in this paper The results are as follows: the influence of reduction conditions on the iron precipitation morphology and bond behavior of the low metallized particles on the reduction rate of the reduced stage is revealed. The control method of controlling the iron precipitation morphology to restrain the multistage flow reduction of iron ore is proposed. The study shows that the mixing of H2 in CO can accelerate the growth rate of iron grain. At the same time, the number of iron nucleation on the surface of the ore powder at the initial stage of reduction is increased, which leads to the change of the newly formed metal iron on the surface of the mineral powder from the whisker to the dense shape. With the increase of the content of the CO-CO2, the newly formed metal iron on the surface of the mineral powder will change from the sharp whisker to the "fairy palm", and the distribution density of the surface iron will be smaller. With the reduction temperature, the distribution density of the surface iron will be smaller. The strength of the iron whisker on the surface of the mineral powder will be weakened. These can significantly reduce the mass of the particles in the low metallization grain flow reduction process. In addition, the iron precipitation morphology of the low metallized particle surface is changed from the whisker shape to the dense shape in the pre reduction section, which can effectively reduce the high metallizing rate particles in the deep reduction section. The MgO addition of the loss of flow reveals the inhibition mechanism of MgO on the bond loss of the different valence iron oxide ore powders during the multistage reduction process. It is suggested that the interfacial reverse behavior between.MgO and the different valence iron oxides with the addition of MgO to inhibit the multilevel flow reduction of the iron ore is shown to be under the medium and low temperature (700 and 800 degrees C). The inhibition effect of MgO on the loss of Fe2O3, Fe3O4 and FeO is mainly the physical barrier effect. At high temperature (900 C), the physical barrier effect is still the main inhibitory effect for the mineral powder with the main composition of Fe2O3; for the mineral powder with the main composition of Fe3O4 and FeO, the barrier layer formed by the chemical reaction is the main inhibition of the bond loss. For reasons, the thickness of the chemical barrier layer formed by the MgO on the surface of the FeO ore powder is greater than that formed on the surface of the Fe3O4 ore powder. The chemical barrier layer is more effective than the inhibitory effect caused by physical adhesion. Therefore, in the multistage fluidized reduction process of Fe3O4 and FeO, the inhibition effect of adding MgO on the bond loss at high temperature is strong to weak. The results of FeOFe3O4Fe2O3. reduction experiments show that the effect of adding MgO to inhibit the reduction of iron ore is less. The preparation of new additive CaO/Fe2O3 strengthens the inhibition effect of calcium component on the loss of bond in the flow reduction process of iron ore, and reveals its inhibition mechanism. The study shows that pure CaO powder and Ca (NO) are analyzed. 3) the suppression of CaO produced by the decomposition of 2. 4H20 is weak, while Fe (NO3) 3. 9H20 and Ca (NO3) 2. 4H20 have a good inhibition effect. The reduction of.CaO/Fe2O3 shows that Ca components mainly inhibit the bond loss by physical barrier effect. Microstructural observation shows that CaO/Fe2O3 is not only possible. The inhibition of the formation of sharp sharp iron can also make the Ca components tightly coated on the surface of the viscous iron and reduce the surface viscosity. In addition, the study shows that the inhibition effect of the additive on the poor performance of Fe2O3 is universally suitable. The carbon deposition and evolution behavior of the iron ore powder in the multistage fluidized reduction process is revealed. The deposition of carbon is not only an inhibitor for the bonding of mineral particles in the reduction process, but also a solid state reducing agent. High reduction potential, low temperature and H2 can accelerate the deposition of carbon in the pre reduction stage, especially the deposition of graphite free carbon. Graphite free carbon can inhibit the formation of iron crystal and reduce the viscosity of the particles. In order to prevent the mineral particles from bonding in high temperature and deep reduction, both graphite free carbon and iron carbide will be consumed by gasification and solid state reduction in high temperature deep reduction, and the reactive activity of graphite free carbon is higher than that of iron carbide. In order to strengthen the application of fluidized technology in direct reduction of iron smelting, the use of high activity is put forward. The feasibility of the reduction of iron ore to higher metallization by the solid solid reaction is demonstrated by the solid solid reaction. In summary, this paper presents a series of efficient manipulation methods based on the evolution characteristics of iron ore in different processes, such as the regulation of iron precipitation. The appearance inhibits the bonding of low metallized particles in the pre reduction section of the multistage fluidized bed, and reduces the amount of MgO added to prevent the loss of the high metallized particles in the deep reduction section. In the FeO section of the multistage fluidized reduction, MgO is added to the chemical barrier layer formed by the solid solid reaction at high temperature. In addition, on the basis of deep analysis of the carbon deposition and evolution behavior in the multistage reduction of iron ore powder, the method of direct use of deposited carbon for high temperature and deep reduction is put forward on the basis of further analysis of the behavior of carbon deposition and evolution in the multistage reduction of iron ore powder. Compared with previous studies, the suppression method proposed in this paper is more close to the actual industrial process and is more useful than the previous research. It is pertinent and efficient, and has strong maneuverability.
【學(xué)位授予單位】：中國科學(xué)院大學(xué)(中國科學(xué)院過程工程研究所)
【學(xué)位級(jí)別】：博士
【學(xué)位授予年份】：2017
【分類號(hào)】：TF552

【參考文獻(xiàn)】

相關(guān)期刊論文 前10條

1 郭磊;高晗;張宗良;郭占成;;包覆磷酸鈣法與混合礦法抑制鐵礦粉黏結(jié)失流[J];鋼鐵;2015年06期

2 朱慶山;李洪鐘;;難選鐵礦流態(tài)化磁化焙燒研究進(jìn)展與發(fā)展前景[J];化工學(xué)報(bào);2014年07期

3 任中山;胡曉軍;薛向欣;周國治;;氬氣下Fe_2O_3-TiO_2體系的固相反應(yīng)[J];北京科技大學(xué)學(xué)報(bào);2014年05期

4 Jean Paul Nepper;Stuart Sneyd;Tobias Stefan;Jan Weckes;李晟;;奧圖泰公司可持續(xù)的鋼鐵冶金技術(shù)[J];世界鋼鐵;2013年05期

5 Qingshan Zhu;Rongfang Wua;Hongzhong Li;;Direct reduction of hematite powders in a fluidized bed reactor[J];Particuology;2013年03期

6 邵劍華;郭占成;唐惠慶;;還原氣氛對(duì)流態(tài)化還原鐵礦粉黏結(jié)失流的影響[J];北京科技大學(xué)學(xué)報(bào);2013年03期

7 Zhong-shan Ren;Xiao-jun Hu;Shen-yang Li;Xiang-xin Xue;Kuo-chih Chou;;Interdiffusion in the Fe_2O_3-TiO_2 system[J];International Journal of Minerals Metallurgy and Materials;2013年03期

8 周勇;張濤;唐海龍;;鐵礦粉流化床直接還原防止粘結(jié)的試驗(yàn)研究[J];鋼鐵釩鈦;2012年04期

9 宋乙峰;朱慶山;;攪拌流化床中超細(xì)氧化鐵粉流態(tài)化及還原實(shí)驗(yàn)研究[J];過程工程學(xué)報(bào);2011年03期

10 邵劍華;郭占成;唐惠慶;;流態(tài)化還原鐵精粉粘結(jié)過程試驗(yàn)研究[J];鋼鐵;2011年02期

相關(guān)博士學(xué)位論文 前1條

1 雷超;碳包覆抑制鐵礦粉流態(tài)化還原粘結(jié)失流研究[D];中國科學(xué)院研究生院(過程工程研究所);2015年

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