以硅铁为还原剂制取金属锂的工艺优化

以硅铁为还原剂,采用真空热还原法制备金属锂. 通过单因素实验及正交实验研究了还原温度、反应时间、制团压力、物料粒度、真空度及还原剂过量率等因素对金属锂还原率的影响. 结果表明,在实验范围内各因素对还原率的影响次序为：还原温度>还原时间>还原剂过量率>制团压力>物料粒度. 硅热真空还原制备金属锂的最佳工艺条件为：还原温度1293 K,还原时间180 min,制团压力30 MPa,物料粒度80 mm,还原剂过量率50%. 在该条件下金属锂的还原率可达97.85%,纯度达99.24%.     

硅铁还原菱镁矿制镁的热力学分析与实验研究

对硅铁还原氧化镁进行了热力学分析,计算出硅铁还原氧化镁的化学反应自由能和临界反应温度,表明造渣反应和真空条件可使临界反应温度由3846 K降到1358 K. 实验得出还原温度1473 K、10.13 Pa真空度、还原时间1 h及CaO/MgO摩尔比1.4时,镁还原率达94.42%,还原金属镁纯度达98.36%,渣团物相主要为Ca2SiO4和SiO2.     

弱氧化性气氛下尘泥含碳球团的还原动力学

在1348~1573 K温度范围内,在弱氧化性气氛下还原尘泥含碳球团,通过动力学实验和还原机理分析,得出影响尘泥含碳球团还原速度的限制性环节为界面反应或局部反应,反应活化能为111.66 kJ/mol,还原速度可由Mckewan方程1-(1-R)1/3=kt表达. 随温度升高,反应速率增大,金属化率和脱锌率提高,金属化率和脱锌率1573 K时最高,分别为79.92%和97.83%, 1348 K时最低,仅为60.17%和75.25%.     

DTRO膜和NF膜处理污酸废水研究

针对某冶炼厂污酸废水的水质特点,提出"预处理+膜处理"的工艺路线.重点研究了废水pH值对CO2除钙的影响、铝盐药剂种类和反应pH值对除砷、氟的影响,最后分别采用DTRO膜和NF膜对预处理后的废水进行分盐浓缩.试验结果表明:当废水pH值为9.0时,废水中ρ(Ca)最低为1.0 mg/L.当铝盐与氟砷摩尔比为1.3:1.0,反应pH值为6.0时,砷和氟的去除率分别为59.3%和88.0%.在7.5 MPa压力下,DTRO膜产水率高达88%,对各种盐分截留率均大于94.5%.而NF膜在4.0 MPa压力下,硫酸根离子和氯离子的分盐率在99%以上.     

两种改性膨润土对废水中F-的吸附研究

选择铝盐和镧盐对膨润土进行改性,制得铝改性膨润土(Al-Bent)和铝镧改性膨润土(Al-La-Bent),并用红外光谱(IR)和X射线衍射(XRD)进行结构表征,通过批量实验比较两种改性膨润土的除氟性能,讨论了不同煅烧温度、pH值和反应时间对除氟效果的影响,采用吸附动力学和等温吸附实验揭示吸附机理.结果表明,Al-La-Bent的除氟能力高于Al-Bent,La的掺入有助于提高吸附效率.当pH值为5.6,投加量为5 g/L、反应温度为25℃,搅拌时间为60 min时,Al-Bent和Al-La-Bent的除氟率分别达到74.65％和78.90％.整个吸附过程符合准二级动力方程,等温曲线用Langmuir方程描述更为准确.     

添加V_2O_5催化制备碳化铁的动力学

研究了923～1073 K的温度范围内,1%V2O5添加剂对70%(ψ)H2 30%(ψ)CH4与铁矿石反应的动力学.运用未反应核模型,求出了不同温度下反应的表观速率常数及反应的表观活化能.结果发现添加V2O5与否铁矿石还原阶段的反应活化能变化不大,表明添加V2O5对铁矿石的还原反应促进作用较弱;添加1%V2O5的试样碳化反应活化能由72 kJ/mol降低到46.5 kJ/mol,减少了35%,说明V2O5对铁碳化反应有较强的促进作用.     

高硫合成气制甲硫醇K2MoO4/SiO2催化剂的研究Ⅰ.镍的促进作用

采用共同浸渍法制备了K2MoO4-NiO/SiO2催化剂,考察了NiO添加量对高硫合成气制甲硫醇K2MoO4/SiO2催化剂性能的影响.活性评价结果表明,添加了NiO的催化剂活性有很大的提高,当Ni/Mo物质的量比为2/9时,CO转化率为72.6%,较未添加NiO的催化剂提高了一倍多.程序升温还原(TPR)表征显示,添加的NiO与Mo有强相互作用,促进了Mo物种的还原.电子自旋共振(ESR)表征显示,反应后的催化剂中可检测到"oxo-Mo(V)"物种和"thio-Mo(V)"物种,K2MoO4-NiO/SiO2催化剂表面主要为"thio-Mo(V)"物种,而K2MoO4/SiO2催化剂表面主要为"oxo-Mo(V)"物种,NiO的添加促进了Mo物种的还原、硫化,可能是造成催化剂活性极大提高的原因.     

沉淀法净化湿法磷酸反应机理的研究

探讨用湿法磷酸制饲料级磷酸氢钙时，采用沉淀法净化湿法磷酸的反应机理。着重介绍镁对产品质量的影响，脱镁过程的控制和脱镁反应动力学；氟在湿法磷酸中的赋存状态，脱氟反应过程和脱氟反应机理。     

高炉铝酸钙炉渣浸出过程动力学

研究了高炉铝酸钙炉渣的浸出动力学,考察了搅拌强度、浸出反应温度、浸出剂初始浓度及炉渣粒度对浸出速率的影响. 结果表明,浸出过程符合一级反应的收缩未反应核模型,宏观动力学方程为1+2(1-xB)-3(1-xB)2/3= 1.108exp(-1906/T)t,表观活化能为15.84 kJ/mol,过程速率为固膜内扩散速率控制. 通过实验数据验证,表明所得模型能较好地描述炉渣的浸出过程.     

Ø1 500 mm氨合成塔内件的改进及应用

通过对合成塔内件使用过程中存在的合成塔塔壁温度高、催化剂第一层平面温差大、第二层反应量大而使温度偏高等问题进行分析,提出改进措施并实施,同时采用新的氨合成催化剂还原理念对催化剂快速彻底还原.改进后,平面温差小于10℃,合成系统压力由31.0 MPa降至28.5 MPa,吨氨电耗下降55 kWh,氨产量由395.6t/d提高至425.0t/d,系统工艺指标得到优化,达到了稳定操作、提高产量、降低能耗的效果.     

白云石烧结的试验研究

通过对不同产地高纯白云石的煅烧试验，揭示了白云石烧结的机理。由于白云石在煅烧过程中碳酸盐分解后形成多孔疏松结构，使其难以烧结致密。轻烧白云石经加水消化或机械粉碎和高压处理可破坏其团聚结构，促进烧结。添加少量Ｆｅ２Ｏ３或ＺｒＯ２等氧化物可降低白云石的烧结温度。     

CHARACTERISTICS OF THE REVERSIBLE REACTION BETWEEN CO2(g) AND CALCINED DOLOMITE

The noncatalytic gas-solid reaction between calcined dolomite and CO₂(g) has been studied in an electrobalance reactor as a function of temperature, pressure, and reactive gas composition. Multicycle tests consisting of as many as ten complete calcination-carbonation cycles were carried out to obtain information on sorbent durability. Surface area, pore volume, and pore size distribution measurements were made to supplement the reaction studies. This reaction is of interest both as a model for studying (he importance of structural property changes in gas-solid reactions, and as the basis for a possible process for the high temperature separation of CO₂ from gas streams.

Calcined dolomite is a superior sorbent to calcined CaCO₃ in that larger fractional conversions of CaO and improved multicycle durability are possible. With CaO obtained from CaCO₃, the first-cycle fractional recarbonation was limited to about 0.80, a value which decreased by 15 to 20% in each subsequent cycle. In contrast, the first-cycle fractional recarbonation of CaO in calcined dolomite was typically 0.90 to 0.95, and this value decreased by only 1 to 2% in each subsequent cycle. These advantages are atlributed to the “excess” pore volume created by the original decomposition of MgCO₃ in dolomite, and by a reduction in the rate of CaCO₃ sintering in the presence of MgO.     

白云灰乳碳酸化工艺研究

中国白云石蕴藏量巨大,白云灰乳碳酸化是白云石碳化法制备轻质碳酸镁、氧化镁等镁化合物的关键步骤之一,关系到镁的产率、产品中钙的含量及生产成本。通过单因素实验和正交实验,研究了碳酸化过程镁的溶出率及重镁水中的钙含量与碳酸化反应温度、反应终点pH、白云灰乳质量浓度的关系,从而为提高碳酸化过程镁的溶出率,实现钙镁的有效分离提供可靠的依据。研究表明：影响镁的溶出率及重镁水中钙含量的主要因素为pH。白云灰乳碳酸化最佳工艺条件：白云灰乳质量浓度为9.00 g/L（以氧化镁计）,反应温度为30 ℃,反应终点pH为7.50。在此条件下镁的溶出率为74.49%,重镁水中钙的质量浓度为0.10 g/L。     

REACTION MECHANISM OF HALF-CALCINED DOLOMITE DURING SULFIDATION

The kinetics of the sulfidation of half-calcined dolomite have been studied over a wide range of reaction conditions in terms of reaction rate and solid phase structure. The rate of reaction shows a strong dependence on temperature, pellet size, and H₂S partial pressure. Analysis of both rate and solid phase structure data indicates that the sulfidation reaction proceeds topochemically on the pellet level with two interfaces below 780° C and with three interfaces above that temperature.     

REACTION MECHANISM OF HALF-CALCINED DOLOMITE DURING SULFIDATION

The kinetics of the sulfidation of half-calcined dolomite have been studied over a wide range of reaction conditions in terms of reaction rate and solid phase structure. The rate of reaction shows a strong dependence on temperature, pellet size, and H₂S partial pressure. Analysis of both rate and solid phase structure data indicates that the sulfidation reaction proceeds topochemically on the pellet level with two interfaces below 780° C and with three interfaces above that temperature.     

Steam gasification of apricot stones with olivine and dolomite as downstream catalysts

Apricot stone steam gasification with olivine and dolomite as downstream catalysts had been carried out for the production of hydrogen-rich gas at atmospheric pressure in a fixed-bed reactor. Reaction temperature, S/B (steam/biomass) ratio, particle size of the catalysts, and calcination of the catalyst, etc., have been studied. The results show that the catalytic activities of calcined olivine and dolomite are higher than the natural ones. With calcined dolomite, a H₂ potential yield of 130.9 gH₂/kg biomass (daf.), which is 86.1% of the stoichiometric yield (152 g H₂/kg biomass (daf.)), is obtained at 850 °C and S/B ratio 0.8, and that with calcined olivine at 800 °C and S/B ratio 0.8 is 67.7 g H₂/kg biomass (daf.), 44.5% of the stoichiometric yield. Calcination of catalysts causes the disappearance of (Mg,Fe)SiO₃ phase and the formation of Fe₂O₃ for olivine and eliminates CO₂ and forms CaO–MgO for dolomite, which may be the reason for the difference in the activity. The calcined dolomite becomes very friable and the calcined olivine keeps its good mechanical intensity after calcination and reaction.     

煅烧工艺制度对轻烧白云石活性度的影响

通过煅烧实验和显微结构观察,研究了煅烧工艺对三种自云石轻烧后活性度的影响,得出如下结论：（1）保温时间为90min,随煅烧温度提高轻烧白云石的活性呈现先升高、后降低的趋势,在1050℃活性度达到最高点。（2）对应某煅烧温度存在一个煅烧时间使轻烧白云石活性最高。（3）白云石的煅烧颗粒尺寸影响煅烧产物活性度。（4）白云石原矿的显微结构对煅烧产物活性度有很大影响,一般晶粒粗大的原矿易得到活性较高的煅烧产物。     

Effective Diffusivities and Convective Coefficients for CaO‐CaSO4 and CaO‐CaCl2 Pellets

Diffusion and convective flow in the pores of pellets formed by compressing mixtures of calcined limestone and CaSO₄/CaCl₂ powders have been studied experimentally by using the single pellet moment technique. The experiments were conducted in a diffusion cell by flowing nitrogen gas (carrier) through both faces of the pellet. Limestone powder was calcined in an atmosphere of N₂ at 800 °C and mixed with CaSO₄/CaCl₂ for diffusion experiments. Effective diffusivity of helium has been estimated by exposing the upper face of the pellet to a pulse of and matching the response peak on the lower face of the pellet with theoretical expressions. The values of the effective diffusivities increased with temperature, but decreased with increasing CaSO₄/CaCl₂ content in the pellet. The convective flow contribution to the diffusion flux was found to increase with increasing pressure drop across the pellet.     

Cyclic calcination/carbonation looping of dolomite modified with acetic acid for CO2 capture

The dolomite modified with acetic acid solution was proposed as a CO₂ sorbent for calcination/carbonation cycles. The carbonation conversions for modified and original dolomites in a twin fixed-bed reactor system with increasing the numbers of cycles were investigated. The carbonation temperature in the range of 630 °C–700 °C is beneficial to the carbonation reaction of modified dolomite. The carbonation conversion for modified dolomite is significantly higher than that for original sorbent at the same reaction conditions with increasing numbers of reaction cycles. The modified dolomite exhibits a carbonation conversion of 0.6 after 20 cycles, while the unmodified sorbent shows a conversion of 0.26 at the same reaction conditions, which is calcined at 920 °C and carbonated at 650 °C. At the high calcination temperature over 920 °C modified dolomite can maintain much higher conversion than unmodified sorbent. The mean grain size of CaO derived from modified dolomite is smaller than that from original sorbent with increasing numbers of reaction cycles. The calcined modified dolomite possesses greater surface area and pore volume than calcined original sorbent during the multiple cycles. The pore volume and pore area distributions for calcined modified dolomite are also superior to those for calcined unmodified sorbent during the looping cycle. The modified dolomite is proved as a new and promising type of regenerable CO₂ sorbent for industrial applications.     

利用白云石开发膨胀水泥的初步研究

研究了白云石的煅烧温度、保温时间以及掺量等对水泥物理性能和膨胀行为的影响规律。研究发现，合理控制白云石的煅烧温度、保温时间、选择合适的掺量，可以使水泥浆体产生适度的膨胀，起到补偿收缩、防止开裂、增加强度、提高抗渗性能等作用。