本文選題：塊狀菱鎂礦 + 煅燒　； 參考：《遼寧科技大學(xué)》2015年碩士論文

【摘要】：重?zé)V砂是鎂質(zhì)耐火原料的重要組成部分,研究塊狀菱鎂礦在大型豎窯煅燒過(guò)程中,隨溫度、壓力變化所發(fā)生的動(dòng)力學(xué)行為,為設(shè)計(jì)大型重?zé)V砂豎窯及制定生產(chǎn)工藝參數(shù)奠定重要基礎(chǔ)。1.采用TG法分別對(duì)邊長(zhǎng)為20mm、30mm、40mm和50mm的立方體塊狀菱鎂礦的熱分解進(jìn)行研究,結(jié)果表明:塊度(L=20~50mm)與活化能的關(guān)系為:E=4.795×L+34.070(kJ·mol-1)。分解前期,Anti-ander方程控制的n=2的3D模型為最概然機(jī)理函數(shù),動(dòng)力學(xué)方程為:dα/dT=6.111×1010×β-1exp[(4.098-0.577×L)×T-1](1+α)2/3[(1+α)1/3-1]-1;分解中期,Avrami-Erofeev方程控制的n=3(Code:AE3)的隨機(jī)成核和隨后長(zhǎng)大模型為最概然機(jī)理函數(shù),動(dòng)力學(xué)方程為:dα/dT=1.422×109×β-1exp[(4.098-0.577×L)×T-1](1-α)[-ln(1-α)]-2;分解后期,Avrami-Erofeev方程控制的n=3/2的隨機(jī)成核和隨后長(zhǎng)大模型為最概然機(jī)理函數(shù),動(dòng)力學(xué)方程為:dα/dT=2.477×109×β-1exp[(4.098-0.577L)×T-1](1-α)[-ln(1-α)]-2。2.采用高溫電爐對(duì)塊狀菱鎂礦進(jìn)行煅燒,研究了塊狀菱鎂礦燒的燒結(jié)特性,結(jié)果表明:燒結(jié)初期母鹽假相顆粒對(duì)燒結(jié)致密化行為有重要影響,溫度在1150~1200℃時(shí),假相顆粒的體積收縮,致其比表面積和顆粒配位數(shù)降低,致密化受到阻礙,出現(xiàn)緩滯現(xiàn)象。1000~1110℃時(shí),Q=412.368 kJ·mol-1;1110~1230℃時(shí),Q=473.990 kJ·mol-1;1230~1300℃時(shí),Q=385.266 kJ·mol-1;燒結(jié)中期致密化系數(shù)由23.51%增加到71.24%,在液相的作用下燒結(jié)傳質(zhì)方式分別為流動(dòng)傳質(zhì)和“溶解一沉淀”;燒結(jié)末期晶界快速移動(dòng),氣孔“匯聚—排除”的速率和晶界向曲率中心的移動(dòng)速率增加,方鎂石晶粒長(zhǎng)大。1600~1700℃時(shí),晶界擴(kuò)散是控制燒結(jié)致密化的主導(dǎo)機(jī)制,晶粒生長(zhǎng)活化能為1.655×103kJ·mol-1,晶粒以結(jié)晶長(zhǎng)大方式為主。1700~1800℃時(shí),體積擴(kuò)散是控制燒結(jié)致密化的主導(dǎo)機(jī)制,晶粒生長(zhǎng)活化能為1.291×103kJ·mol-1,晶粒以聚晶長(zhǎng)大方式為主。3.采用熱壓燒結(jié)法,模擬塊狀菱鎂礦在壓力作用下的燒結(jié)過(guò)程,結(jié)果表明:在勻速升溫階段,壓力的增加,縮短了致密化時(shí)間,降低了試樣致密化溫度;在保溫階段,試樣以塑性流動(dòng)和擴(kuò)散的方式致密化;在勻速降溫階段,壓力越大,試樣彈性模量越高,應(yīng)力釋放產(chǎn)生的彈性形變?cè)酱?相對(duì)密度降低速率越快。通過(guò)對(duì)試樣的燒結(jié)過(guò)程和顯微結(jié)構(gòu)分析,自重壓力為5MPa時(shí)的試樣致密化程度和方鎂石結(jié)晶度最高。
[Abstract]:Refired magnesite is an important part of magnesia refractory raw material. The dynamic behavior of block magnesite during calcination of large vertical kiln with temperature and pressure is studied.It lays an important foundation for designing large-scale heavy-fired magnesite shaft kiln and making production process parameters. 1.The thermal decomposition of cubic block magnesite with side length of 20 mm ~ 30 mm ~ 40 mm and 50mm is studied by TG method. The results show that the relation between the activation energy and the block size is 4.795 脳 L 34.070(kJ mol ~ (-1).The 3D model controlled by Anti-ander 's equation is the most probable mechanism function, and the kinetic equation is: 1 偽 2 / 3 [1 偽 1 / 1 / 3 1] -1 / 1, the random nucleation and subsequent growth model of Avrami-Erofeev equation controlled by the Avrami-Erofeev equation are the most probable mechanism functions, and the kinetic equation is:: d 偽 -dT 6.111 脳 1010 脳 尾 -1exp [4.098-0.577 脳 L) 脳 T ~ (-1) 脳 T ~ (-1)] -1.The random nucleation and subsequent growth model of Avrami-Erofeev equation control are the most probable mechanism functions.The kinetic equation is: 1. 422 脳 10 ~ 9 脳 10 ~ 9 脳 尾 -1exp [4.098-0.577 脳 T ~ (-1) 脳 T ~ (-1)] (-lnn ~ (1- 偽))] -2; the random nucleation and subsequent growth model controlled by the Avrami-Erofeev equation is the most probable mechanism function, and the kinetic equation is:: d 偽 / D _ (DT) 2.477 脳 109 脳 尾 -1exp [4.098-0.577L) 脳 T-1] 1- 偽) [-ln1- 偽] -2.2.The sintering characteristics of bulk magnesite were studied by means of high temperature electric furnace. The results showed that the initial sintering densification was affected by the pseudo phase particles of mother salt, and the sintering temperature was 1 150 ~ 1 200 鈩，

本文編號(hào)：1767268