鋼渣中二價氧化物活化及其膠凝活性研究
發(fā)布時間：2018-09-01 08:05
【摘要】：鋼渣是將煉鋼過程中高溫熔渣冷卻得到的一種固態(tài)廢渣。因含鐵量高且存在約20%的無活性二價氧化物固溶體(簡稱RO相),導(dǎo)致鋼渣質(zhì)硬難磨、膠凝活性低,無法實現(xiàn)大規(guī)模的高附加值利用。本文依托國家自然科學(xué)基金課題“轉(zhuǎn)爐鋼渣原位氧化及其熟料燒成化學(xué)基礎(chǔ)研究”(編號:21566008),以廣西柳鋼的熱悶轉(zhuǎn)爐鋼渣為研究對象,基于RO相置換型固溶體特性,提出將外摻CaO、Al_2O_3與RO相分離所得組分等進行高溫化合,再形成具有膠凝性的硅酸鹽礦物,從而從本質(zhì)上提升鋼渣活性的技術(shù)思路。開展了RO相分離及硅酸鹽礦物再化合工藝研究,探討了組分、溫度、礦化劑等因素對改性鋼渣膠凝活性的影響。圍繞上述研究,主要具體研究工作及取得成果如下:首先,借鑒TG-DSC和XRD等表征方法探索熱處理工藝對鋼渣中RO相演變趨勢及存在形態(tài)的影響:隨著熱處理溫度的升高和保溫時間的延長,熔渣中RO相和鐵酸鹽相含量逐漸減少直至消失,MgO和Fe_2O_3固溶加劇,此時Fe_2O_3和MgO活度較高。在風(fēng)冷有條件下RO相演變成鐵鎂尖晶石MgFe_2O_4。進而在熔渣中Fe_2O_3活度較高的狀態(tài)下,即在物相反應(yīng)中Fe_2O_3參與反應(yīng)的有效濃度較高時,探究調(diào)節(jié)組份CaO和Al_2O_3對鋼渣中RO相活化、硅酸鹽礦物再化合的影響。XRD和SEM-BEI分析表明:在Al_2O_3摻量為3%的條件下,CaO摻量在10%~25%時,隨著CaO摻量增加RO相消失,演變?yōu)檫^渡相MgFe_2O_4;隨后MgFe_2O_4逐漸減少,C_2S和C_2F逐漸增加;當(dāng)CaO摻量達到15%時,MgFe_2O_4消失,逐漸出現(xiàn)游離氧化鎂(f-MgO),摻入CaO先后分別與SiO2、MgFe_2O_4反應(yīng)。當(dāng)鈣摻量達到25%時為極限摻量值,轉(zhuǎn)爐鋼渣中出現(xiàn)了游離氧化鈣。在高溫狀態(tài)下,CaO按酸性氧化物的強弱依次與SiO2及RO相分離出的Fe_2O_3再化合形成硅酸鹽礦物和鐵酸鹽礦物。最后,向重構(gòu)鋼渣中加入礦化劑穩(wěn)定RO相分離出的MgO。實驗結(jié)果表明:礦化劑可促進膠凝礦物相包裹f-MgO,但無法消化所有f-MgO,對MgO固溶量微弱。石膏促進效果優(yōu)于五氧化二磷。CaSO4不僅有助于鋼渣中的RO相活化及固溶MgO,還有效提高了鋼渣的膠凝活性。在CaO和CaSO4摻量分別為15%、3%時,鋼渣水化熱提高了2.78倍,3d和28d強度分別提高的28%和4.6%�？傮w研究表明,調(diào)節(jié)劑和礦化劑可有效活化RO相,提高了鋼渣的水化放熱總量和力學(xué)性能,保證了鋼渣摻合料的安定性。為實現(xiàn)鋼渣高附加值的廣泛應(yīng)用奠定了基礎(chǔ)。
[Abstract]:Steel slag is a kind of solid waste slag which is obtained by cooling the high temperature slag in the steelmaking process. Because of the high iron content and the existence of 20% inactive divalent oxide solid solution (RO phase), the steel slag is hard and hard to grind, and the cementitious activity is low, which can not realize the large-scale utilization of high added value. In this paper, based on the National Natural Science Foundation of China, "basic Research on the Chemistry of Converter Slag In-situ Oxidation and clinker Sintering" (No.: 21566008), the hot stuffing converter slag of Guangxi Liugang is taken as the research object, based on the characteristics of RO phase replacement solid solution. The technical idea of improving the activity of steel slag is put forward by combining the components separated by CaO,Al_2O_3 and RO phase at high temperature and then forming the silicate mineral with cementitious property. RO phase separation and silicate mineral recombination were studied. The effects of composition, temperature and mineralizer on the cementitious activity of modified steel slag were discussed. Around the above research, the main research work and achievements are as follows: first, The influence of heat treatment process on the evolution trend and morphology of RO phase in steel slag was explored by using TG-DSC and XRD characterization methods: with the increase of heat treatment temperature and the prolongation of heat preservation time, The content of RO phase and ferrate phase in slag decreased gradually until the disappearing MgO and Fe_2O_3 solution increased, and the activities of Fe_2O_3 and MgO were higher. Evolution of RO phase into ferrite spinel MgFe_2O_4. under air-cooled condition Furthermore, when the activity of Fe_2O_3 in slag is high, that is, when the effective concentration of Fe_2O_3 to participate in the reaction is higher, the activation of RO phase in steel slag by adjusting the components of CaO and Al_2O_3 is explored. The effect of silicate mineral recombination. XRD and SEM-BEI analysis show that when the content of Al_2O_3 is 3%, the RO phase disappears with the increase of CaO content, and then the MgFe_2O_4 decreases gradually, C2S and C2F increase gradually with the increase of CaO content. When the CaO content reached 15%, the MgFe _ 2O _ 4 disappeared and the free magnesium oxide (f-MgO) appeared gradually, and then the CaO reacted with SiO2,MgFe_2O_4 respectively. When the content of calcium is up to 25, the free calcium oxide appears in converter slag. At high temperature, the Fe_2O_3 recombined with SiO2 and RO to form silicate minerals and ferrate minerals according to the strength of acidic oxides. Finally, MgO. was separated by adding mineralizer to the reconstructed steel slag to stabilize the RO phase. The experimental results show that the mineralizer can promote the encapsulation of f-MgO in the cementitious mineral phase, but it can not digest all f-MgO, and the solution to MgO is weak. The effect of gypsum is better than that of phosphorus pentoxide. CaSO4 not only contributes to the activation of RO phase and solution of MgO, in steel slag, but also improves the cementitious activity of steel slag. When the content of CaO and CaSO4 is 15 and 3 respectively, the hydration heat of steel slag increases by 2.78 times and 28 days and the strength increases by 28% and 4.6%, respectively. The overall study shows that the modifier and mineralizer can effectively activate the RO phase, improve the total hydration heat release and mechanical properties of steel slag, and ensure the stability of steel slag admixture. It lays a foundation for the wide application of steel slag with high added value.
【學(xué)位授予單位】：桂林理工大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：X757;TQ132.2
本文編號：2216598
[Abstract]:Steel slag is a kind of solid waste slag which is obtained by cooling the high temperature slag in the steelmaking process. Because of the high iron content and the existence of 20% inactive divalent oxide solid solution (RO phase), the steel slag is hard and hard to grind, and the cementitious activity is low, which can not realize the large-scale utilization of high added value. In this paper, based on the National Natural Science Foundation of China, "basic Research on the Chemistry of Converter Slag In-situ Oxidation and clinker Sintering" (No.: 21566008), the hot stuffing converter slag of Guangxi Liugang is taken as the research object, based on the characteristics of RO phase replacement solid solution. The technical idea of improving the activity of steel slag is put forward by combining the components separated by CaO,Al_2O_3 and RO phase at high temperature and then forming the silicate mineral with cementitious property. RO phase separation and silicate mineral recombination were studied. The effects of composition, temperature and mineralizer on the cementitious activity of modified steel slag were discussed. Around the above research, the main research work and achievements are as follows: first, The influence of heat treatment process on the evolution trend and morphology of RO phase in steel slag was explored by using TG-DSC and XRD characterization methods: with the increase of heat treatment temperature and the prolongation of heat preservation time, The content of RO phase and ferrate phase in slag decreased gradually until the disappearing MgO and Fe_2O_3 solution increased, and the activities of Fe_2O_3 and MgO were higher. Evolution of RO phase into ferrite spinel MgFe_2O_4. under air-cooled condition Furthermore, when the activity of Fe_2O_3 in slag is high, that is, when the effective concentration of Fe_2O_3 to participate in the reaction is higher, the activation of RO phase in steel slag by adjusting the components of CaO and Al_2O_3 is explored. The effect of silicate mineral recombination. XRD and SEM-BEI analysis show that when the content of Al_2O_3 is 3%, the RO phase disappears with the increase of CaO content, and then the MgFe_2O_4 decreases gradually, C2S and C2F increase gradually with the increase of CaO content. When the CaO content reached 15%, the MgFe _ 2O _ 4 disappeared and the free magnesium oxide (f-MgO) appeared gradually, and then the CaO reacted with SiO2,MgFe_2O_4 respectively. When the content of calcium is up to 25, the free calcium oxide appears in converter slag. At high temperature, the Fe_2O_3 recombined with SiO2 and RO to form silicate minerals and ferrate minerals according to the strength of acidic oxides. Finally, MgO. was separated by adding mineralizer to the reconstructed steel slag to stabilize the RO phase. The experimental results show that the mineralizer can promote the encapsulation of f-MgO in the cementitious mineral phase, but it can not digest all f-MgO, and the solution to MgO is weak. The effect of gypsum is better than that of phosphorus pentoxide. CaSO4 not only contributes to the activation of RO phase and solution of MgO, in steel slag, but also improves the cementitious activity of steel slag. When the content of CaO and CaSO4 is 15 and 3 respectively, the hydration heat of steel slag increases by 2.78 times and 28 days and the strength increases by 28% and 4.6%, respectively. The overall study shows that the modifier and mineralizer can effectively activate the RO phase, improve the total hydration heat release and mechanical properties of steel slag, and ensure the stability of steel slag admixture. It lays a foundation for the wide application of steel slag with high added value.
【學(xué)位授予單位】：桂林理工大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：X757;TQ132.2
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