The utilization of ironsand for preparing oxidized pellets poses challenges,including slow oxidation and low consolidation strength.The effects and function mechanisms of high-pressure grinding roll(HPGR)pretreatment ...The utilization of ironsand for preparing oxidized pellets poses challenges,including slow oxidation and low consolidation strength.The effects and function mechanisms of high-pressure grinding roll(HPGR)pretreatment on the oxidation and consolidation of ironsand pellets were investigated,and the energy utilization efficiency of HPGR with different roller pressure intensities was evaluated.The results indicate that HPGR pretreatment at 8 MPa improves the ironsand properties,with the specific surface area increasing by 740 cm^(2) g^(-1) and mechanical energy storage increasing by 2.5 kJ mol^(-1),which is conducive to oxidation and crystalline connection of particles.As roller pressure intensity increases to 16 MPa,more mechanical energy of HPGR is applied for crystal activation,with mechanical energy storage further rising by 18.1 kJ mol^(-1).The apparent activation energy for pellet oxidation initially decreases and then increases,reaching a minimum at 12 MPa.Simultaneously,the roasted pellets porosity decreases by 2.8%,while the compressive strength increases by 789 N.At higher roller pressure intensity,the densely connected structure between particles impedes gas diffusion within the pellets,diminishing the beneficial effects of HPGR on pellet oxidation.Moreover,excessive roller pressure intensity decreases the HPGR energy utilization efficiency.The optimal HPGR roller pressure intensity for ironsand is 12 MPa,at which the specific surface area increases by 790 cm^(2) g^(-1),mechanical energy storage increases by 10.6 kJ mol^(-1),the compressive strength of roasted pellets rises to 2816 N,and the appropriate preheating and roasting temperatures decrease by 250 and 125°C,respectively.展开更多
对印度尼西亚海砂矿氧化性球团氢气还原的规律做了较详细的研究.实验采用失重的方法,通过对反应过程的物相变化、热力学以及动力学方面的分析,探究了海砂球团矿氢气还原的机理.结果表明:温度在800℃和850℃,还原反应的最终产物主要是Fe ...对印度尼西亚海砂矿氧化性球团氢气还原的规律做了较详细的研究.实验采用失重的方法,通过对反应过程的物相变化、热力学以及动力学方面的分析,探究了海砂球团矿氢气还原的机理.结果表明:温度在800℃和850℃,还原反应的最终产物主要是Fe Ti O3,整个反应限制环节是由两个不同阶段的过程组成,反应开始阶段由界面化学反应控制,之后由界面化学反应与内扩散共同控制;在900、950和1000℃三个温度下,反应产物中有钛氧化物出现,整个还原反应由三个不同的限制性环节组成,开始由界面化学反应控制,反应中间阶段是由界面化学反应和内扩散共同控制,反应后期则是由内扩散控制为主.展开更多
基金financially supported by the General Program of National Natural Science Foundation of China(No.52174330)Hunan Provincial Innovation Foundation for Postgraduate(No.QL20220069)Postgraduate Innovative Project of Central South University(No.1053320214756).
文摘The utilization of ironsand for preparing oxidized pellets poses challenges,including slow oxidation and low consolidation strength.The effects and function mechanisms of high-pressure grinding roll(HPGR)pretreatment on the oxidation and consolidation of ironsand pellets were investigated,and the energy utilization efficiency of HPGR with different roller pressure intensities was evaluated.The results indicate that HPGR pretreatment at 8 MPa improves the ironsand properties,with the specific surface area increasing by 740 cm^(2) g^(-1) and mechanical energy storage increasing by 2.5 kJ mol^(-1),which is conducive to oxidation and crystalline connection of particles.As roller pressure intensity increases to 16 MPa,more mechanical energy of HPGR is applied for crystal activation,with mechanical energy storage further rising by 18.1 kJ mol^(-1).The apparent activation energy for pellet oxidation initially decreases and then increases,reaching a minimum at 12 MPa.Simultaneously,the roasted pellets porosity decreases by 2.8%,while the compressive strength increases by 789 N.At higher roller pressure intensity,the densely connected structure between particles impedes gas diffusion within the pellets,diminishing the beneficial effects of HPGR on pellet oxidation.Moreover,excessive roller pressure intensity decreases the HPGR energy utilization efficiency.The optimal HPGR roller pressure intensity for ironsand is 12 MPa,at which the specific surface area increases by 790 cm^(2) g^(-1),mechanical energy storage increases by 10.6 kJ mol^(-1),the compressive strength of roasted pellets rises to 2816 N,and the appropriate preheating and roasting temperatures decrease by 250 and 125°C,respectively.
文摘对印度尼西亚海砂矿氧化性球团氢气还原的规律做了较详细的研究.实验采用失重的方法,通过对反应过程的物相变化、热力学以及动力学方面的分析,探究了海砂球团矿氢气还原的机理.结果表明:温度在800℃和850℃,还原反应的最终产物主要是Fe Ti O3,整个反应限制环节是由两个不同阶段的过程组成,反应开始阶段由界面化学反应控制,之后由界面化学反应与内扩散共同控制;在900、950和1000℃三个温度下,反应产物中有钛氧化物出现,整个还原反应由三个不同的限制性环节组成,开始由界面化学反应控制,反应中间阶段是由界面化学反应和内扩散共同控制,反应后期则是由内扩散控制为主.
