發(fā)布時(shí)間：2018-04-25 08:50

  本文選題：煉鋼爐渣 + 離子與分子共存理論��； 參考：《北京科技大學(xué)》2017年博士論文

【摘要】：隨著鋼渣大量堆積以及磷礦資源的匱乏,如何實(shí)現(xiàn)鋼渣循環(huán)利用和高品位磷資源的回收成為眾多冶金企業(yè)關(guān)注焦點(diǎn)之一。本論文針對(duì)鋼渣中磷的組成及賦存特點(diǎn),提出采用選擇性富集與相分離的方法來(lái)分離鋼渣中磷酸鹽的思路,闡明了鋼渣中磷酸鹽的結(jié)晶行為,揭示了其選擇性富集、選擇性結(jié)晶長(zhǎng)大、及相分離過(guò)程中的影響因素。選擇性富集與分離的學(xué)術(shù)思想,不僅能夠充分利用鋼渣顯熱,而且能夠?qū)崿F(xiàn)鋼渣中磷酸鹽及富鐵相的分離,基本實(shí)現(xiàn)了鋼渣的高效回收利用。木論文采用離子與分子共存理論(IMCT),開(kāi)發(fā)出計(jì)算CaO-SiO_2-FeO-Fe_2O_3-P_2O_5五元渣系中結(jié)構(gòu)單元或離子對(duì)的質(zhì)量作用濃度N_i的熱力學(xué)模型,即IMCT-N_i模型,并且.定義了評(píng)價(jià)鋼渣中磷酸鹽富集行為的富集可能性N_(_(ci-cj))和富集程度R_(ci-cj)兩個(gè)參數(shù),研究了五元渣系中磷酸鹽的富集行為,并且通過(guò)設(shè)計(jì)的實(shí)驗(yàn),驗(yàn)證了不同堿度范圍的鋼渣中磷酸鹽的富集機(jī)理。五元渣系在1773 K時(shí)可生成3CaO·P_2O_5(C_3P),其易與2CaO·SiO_2(C_2S)結(jié)合,在合適的冷卻制度下,生成2CaO·SiO_2-3CaO·P_2O_5 (C_2S-C_3P)固溶體；高堿度(2.0B3.5)條件下定義的N_(C_2S-C_3P)或R_(C_2S-C_3P)與爐渣二元堿度或(%FetO)/(%CaO)呈非對(duì)稱(chēng)拋物線關(guān)系；當(dāng)堿度為2.5,(%Fe_tO)/(%CaO)為0.955時(shí),定義的N_(C_2S-C_3P)或R_(C_2S-C_3P)達(dá)到最大具體數(shù)值,其中RC_2S-C_3P約為85%。低堿度(1.0B2.0)五元渣系中隨著堿度逐步增高,渣中磷酸鹽富集相C_2S-C_3P中P_2O_5的質(zhì)量百分?jǐn)?shù)(%P_2O_5)呈現(xiàn)一種倒“V”型變化。當(dāng)堿度為1.3時(shí),渣中磷酸鹽富集相中(%P_2O_5)達(dá)到最大約為30%。通過(guò)理論計(jì)算和實(shí)驗(yàn)檢測(cè)相結(jié)合的方式, 研究了CaO-SiO_2-FeO-Fe_2O_3-Al_2O_3-P_2O_5六元渣系和CaO-SiO_2-MgO-FeO-Fe_2O_3-MnO-Al_2O_3-P_2O_5元渣系中磷酸鹽富集行為,獲得了多元渣系在冷卻過(guò)程中磷酸鹽達(dá)到最優(yōu)的爐渣成分,闡明了多元煉鋼渣系中決定磷酸鹽富集的關(guān)鍵性因素是渣中游離C_2S (f-C_2S)的生成量。多元煉鋼渣系中Al_2O_3組元和爐渣中C_2S結(jié)合生成鈣鋁黃長(zhǎng)石C_2AS相,可降低煉鋼爐渣中游離C_2S(f-C_2S)相的量,進(jìn)而間接影響煉鋼爐渣中磷酸鹽富集相nC_2S-C_3P內(nèi)(%P_2O_5)含量。因此,六元煉鋼爐渣獲得較好磷酸鹽富集程度,爐渣二元堿度B和Al_2O_3含量需要滿足(%Al_2O_3)=-27.70+21.62B的耦合關(guān)系,此時(shí)磷酸鹽富集相中(%P_2O_5)約達(dá)到30.0%；八元煉鋼爐渣四元堿度Q為1.23時(shí),磷酸鹽富集率較高,磷酸鹽富集相中(%P_2O_5)可達(dá)24.23%。在前期熱力學(xué)研究的基礎(chǔ)上,對(duì)不同渣系中磷酸鹽的結(jié)晶動(dòng)力學(xué)進(jìn)行了研究。采用Image-Pro-Plus(IPP)圖像分析軟件,統(tǒng)計(jì)計(jì)算出了不同溫度制度(取出溫度、保溫時(shí)間、冷卻速率)下,上述五元和八元煉鋼渣系中磷酸鹽富集相的析晶而積,建立了磷酸鹽富集相的平均結(jié)晶分?jǐn)?shù)與溫度之間的關(guān)系：計(jì)算得到了爐渣在冷卻過(guò)程中磷酸鹽析出的結(jié)晶參數(shù);通過(guò)不同速率常數(shù)k(T),獲得了不同模型的表觀活化能E_i。五元渣系中磷酸鹽在結(jié)晶過(guò)程中的Avrami常數(shù)n值平均為0.472,八元渣系的Avrami常數(shù)n值平均為0.442;兩個(gè)渣系的磷酸鹽結(jié)晶機(jī)理基本一致：均為擴(kuò)散反應(yīng)控速,生成棒狀一維結(jié)構(gòu),且形核速率隨時(shí)間下降。五元渣系磷酸鹽富磷相結(jié)晶過(guò)程中,Van't Hoff速率常數(shù)Ink的表達(dá)式Innk=53.80+11163.69/T-7.49InT-0.005T,表觀活化能E=-278.52 KJ/mol八元渣系磷酸鹽富磷相結(jié)晶過(guò)程中,Van't Hoff速率常數(shù)Ink的表達(dá)式：Ink=40.5+7966.67/T-5.67InT-0.004T,表觀活化能E=-189.84K.J/mol。通過(guò)調(diào)整煉鋼爐渣成分及合適冷卻制度,得到了大顆粒尺寸的磷酸鹽富集相,采用磁選技術(shù)對(duì)其進(jìn)行了分離的初步研究。當(dāng)控制磁選條件為：爐渣破碎粒度200目以上,磁選強(qiáng)度為3.0 KOe時(shí),五元煉鋼爐渣中磷組分的磁選率為74%,鐵組分的磁選率為69%；八元煉鋼爐渣中磷組分的磁選率為69.84%,鐵組分的磁選率為67.74%。
[Abstract]:With the accumulation of steel slag and the shortage of phosphate mineral resources, how to recycle steel slag and recycle high grade phosphorus resources has become one of the focus of attention of many metallurgical enterprises. In this paper, the idea of separating phosphate in steel slag by selective enrichment and phase separation is proposed in view of the composition and occurrence characteristics of phosphorus in steel slag. The crystallization behavior of phosphate in steel slag reveals its selective enrichment, selective crystallization and growth, and the influencing factors in the process of phase separation. The academic thought of selective enrichment and separation can not only make full use of the explicit heat of steel slag, but also realize the separation of phosphate and iron rich phase in steel slag, and basically realize the efficient recovery of steel slag. Using the theory of coexistence of ions and molecules (IMCT), the paper developed a thermodynamic model for calculating the mass action concentration N_i of the structural unit or ion pair in the CaO-SiO_2-FeO-Fe_2O_3-P_2O_5 five element slag system, that is, the IMCT-N_i model, and defined the enrichment possibility N_ (ci-cj) and the enrichment degree R_ (ci-) for the evaluation of phosphate enrichment in steel slag. CJ) two parameters, the enrichment behavior of phosphate in the five element slag system was studied, and the enrichment mechanism of phosphate in steel slag with different alkalinity range was verified by the design experiment. The five element slag system can produce 3CaO P_2O_5 (C_3P) at 1773 K, which is easy to combine with 2CaO SiO_2 (C_2S) and generates 2CaO SiO_2-3CaO. P_2O_ under the appropriate cooling system. 5 (C_2S-C_3P) solid solution; the N_ (C_2S-C_3P) or R_ (C_2S-C_3P) defined under the condition of high alkalinity (2.0B3.5) has an asymmetrical parabolic relationship with the two yuan alkalinity or (%FetO) / (%CaO) of the slag; when the alkalinity is 2.5, (%Fe_tO) / (%CaO) 0.955, the definition of N_ (C_2S-C_3P) or the maximum specific value is reached, of which it is about low alkalinity. (1.0B2.0) with the increase of alkalinity in the five element slag system, the mass percentage (%P_2O_5) of P_2O_5 in the phosphate enriched phase C_2S-C_3P in the slag presents an inverted "V" type. When the alkalinity is 1.3, the maximum of the phosphate enriched phase in the slag (%P_2O_5) is approximately 30%. through the combination of theoretical calculation and experimental detection, and CaO-SiO_2- has been studied. The enrichment behavior of phosphate in the FeO-Fe_2O_3-Al_2O_3-P_2O_5 six element slag system and the CaO-SiO_2-MgO-FeO-Fe_2O_3-MnO-Al_2O_3-P_2O_5 element slag system has been obtained, and the optimum slag composition is obtained during the cooling process of the multiple slag system. The key factor for determining the phosphate concentration in the multiple steelmaking slag system is the birth of the free C_2S (f-C_2S) in the slag. The amount of Al_2O_3 component in the slag system of multiple steelmaking slag and C_2S in slag to produce calcium aluminum feldspar C_2AS phase can reduce the amount of free C_2S (f-C_2S) phase in the slag of steelmaking, and then indirectly affect the content of nC_2S-C_3P (%P_2O_5) in the phosphate enrichment phase of the steelmaking slag. Therefore, the slag of six yuan smelting steel furnace slag is enriched with good phosphate, and the slag is two yuan base. The content of B and Al_2O_3 needs to meet the coupling relationship of (%Al_2O_3) =-27.70+21.62B, at this time, the phosphate enrichment phase (%P_2O_5) is about 30%, and when the four yuan alkalinity Q of the eight element steelmaking slag is 1.23, the phosphate enrichment rate is higher, and the phosphate enriched phase (%P_2O_5) can reach 24.23%. on the basis of the previous thermodynamic study, and phosphate in different slag systems Image-Pro-Plus (IPP) image analysis software was used to calculate the crystallization of the phosphate enriched phase in the five and eight yuan steelmaking slag system, and the correlation between the average crystalline fraction of the phosphate enriched phase and the temperature was established. The crystallization parameters of the phosphoric acid salting out of the slag during the cooling process are calculated. Through the different rate constants K (T), the n value of the Avrami constant n in the crystallization process of the apparent activation energy E_i. of different models is 0.472, the average Avrami constant of the slag system is eight, and the average of the n value of the slag system is 0.442, and the two phosphates in the slag system. The crystal mechanism is basically the same as the diffusion reaction control speed, forming a rod like one-dimensional structure and decreasing the nucleation rate with time. The expression Innk=53.80+11163.69/T-7.49InT-0.005T of Van't Hoff rate constant Ink during the crystallization of phosphate rich phase of the five element slag system, the crystallization process of the apparent activation energy E= -278.52 KJ/mol in phosphate rich phosphorous phase The expression of Van't Hoff rate constant Ink: Ink=40.5+7966.67/T-5.67InT-0.004T, apparent activation energy E=-189.84K.J/mol. by adjusting the composition of steelmaking slag and suitable cooling system, a large particle size phosphate enriched phase was obtained, and a preliminary study of separation was carried out by magnetic separation technology. When the grain size is more than 200 mesh and the magnetic separation strength is 3 KOe, the magnetic separation rate of the phosphorus component in the slag of five yuan steelmaking is 74%, the magnetic separation rate of the iron component is 69%, the magnetic separation rate of the phosphorus component in the eight yuan steelmaking slag is 69.84%, and the magnetic separation rate of the iron component is 67.74%..

【學(xué)位授予單位】：北京科技大學(xué)
【學(xué)位級(jí)別】：博士
【學(xué)位授予年份】：2017
【分類(lèi)號(hào)】：X757;O652.6

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