基于CO2循环的低碳高效白云石煅烧新工艺

白云石是一种广泛应用的冶金、建材和化工原料。针对白云石煅烧过程中CO₂排放严重等问题，构建了基于CO₂循环载热与资源化回收的白云石低碳煅烧竖窑新工艺。通过白云石（CaCO₃·MgCO₃）煅烧过程的Gibbs自由能变计算，发现提高煅烧温度（50~100 K）可有效克服CO₂对反应的抑制作用；通过纯CO₂环境中CaCO₃分解过程的热重实验分析，验证了CO₂循环煅烧白云石煅烧的可行性；通过化学反应动力学计算，解析了全CO₂组分环境下CO₂压力对CaCO₃·MgCO₃高温分解过程的影响，并发现提高CO₂压力可促进气固传热，从而提升分解速率和改善矿料分解均匀性；对CO₂循环煅烧工艺系统能-质平衡计算表明：该工艺理论能耗仅为140 kg/(t 煅白)，且煅烧过程的CO₂排放降低70%以上，环境效益显著。     

一种钛白粉转窑煅烧尾气余热利用新装置

钛白粉煅烧转窑尾气的高湿、高硫、高酸露点的特性使得转窑尾气余热利用过程中换热器寿命不理想。在总结已有尾气余热利用方式存在问题的基础上,提出了一种长寿命、易维护的套管式热管余热利用装置,该装置由彼此分离的换热套管通过弯头、法兰连接成为整体,尾气垂直横掠双层套管段,与高硫、高湿的尾气通过相变介质的相变完成热量由尾气向取热介质的转移,产生钛白粉生产工艺所急需的蒸汽,双层管的相变换热套管对比单层管的重力热管换热器寿命明显延长;连接换热套管的单层管弯头不与高湿、高硫尾气换热,大大减轻了尾气对单层管的腐蚀。换热器应用在3.6 m×58 m的钛白粉煅烧窑上,每年可以产生0.9 MPa的水蒸气1.12万t,为企业带来可观的经济效益。     

硫酸镍煅烧的实验研究

硫酸镍煅烧可以产生镍氧化物,作为制备氧化镍的原料。以六水硫酸镍为原料,采用热重-差热分析（TG-DTA）、X射线衍射（XRD）分析研究了其煅烧过程并对产物进行了表征。研究结果表明,硫酸镍煅烧过程分为3个阶段：第一阶段（27~250 ℃）及第二阶段（250~600 ℃）为脱水阶段;第三阶段（600~900 ℃）为分解阶段。在煅烧温度为850 ℃、煅烧时间为30 min、粒度为74~147 μm条件下,硫酸镍煅烧产物为氧化镍。     

Preparation and characterization of alumina submicron fibers by plasma assisted calcination

Ceramic alumina nanofibers were prepared by plasma-assisted calcination (PAC) using atmospheric pressure plasma. Electrospun polyvinyl pyrrolidone/aluminium butoxide fibers were pre-treated by plasma generated in ambient air using a special type of coplanar dielectric barrier discharge. The effect of plasma on fibers and structural, chemical and crystalline properties of obtained ceramic nanofibers were characterized using X-Ray Photoelectron Spectroscopy and Scanning Electron Microscopy, Energy-dispersive X-ray Spectroscopy and X-Ray Diffraction. Thermogravimetric and differential thermal analysis were used for the study of thermal behaviour of untreated and plasma-treated samples. The ceramic fibers prepared by PAC exhibit suitable chemical composition, higher porosity, high length of fibers and better crystalline properties with simultaneous simplifying of the sintering process. The plasma pre-treatment of fibers results in a shortening of following thermal treatment, decrease of the required temperature and excludes a slow temperature increase as prevention of fibrous structure degradation typical in preparation of ceramic fibers by polymer-template techniques.     

Influence of processing on stability,microstructure and thermoelectric properties of Ca3Co4 − xO9 + δ

Due to high figure of merit, Ca₃Co_4 ? xO_9 + δ (CCO) has potential as p-type material for high-temperature thermoelectrics. Here, the influence of processing including solid state sintering, spark plasma sintering and post-calcination on stability, microstructure and thermoelectric properties is reported. By a new post-calcination approach, single-phase materials were obtained from precursors to final dense ceramics in one step. The highest zT of 0.11 was recorded at 800 °C for CCO with 98 and 72% relative densities. In situ high-temperature X-ray diffraction in air and oxygen revealed a higher stability of CCO in oxygen (～970 °C) than in air (～930 °C), with formation of Ca₃Co₂O₆ which also showed high stability in oxygen, even at 1125 °C. Since achievement of phase pure high density CCO by post-calcination method in air is challenging, the phase stability of CCO in oxygen is important for understanding and further improvement of the method.     

Understanding the correlation between calcination temperature and performance in low-temperature methanation over Ni-Zr/Al2O3 catalysts

Low-temperature methanation of CO in the continuous stirred tank reactor (CSTR) over Zr doped Ni/Al₂O₃ catalyst calcined at different temperatures (673, 723, and 823 K) was investigated. XRD, TPR, XPS, ICP, SEM, and S-TPR techniques were employed to characterize the fresh and spent catalysts. Based on the characterization results, it was found that low-temperature (673 K) calcination could effectively prohibit the formation of NiAl₂O₄ spinel, thereby resulting in more reducible NiO particles, which were the essential precursor of methanation active sites over the catalyst surface. Thus, the highest CO conversion of 93.6% was achieved over the 25N3ZA-673 catalyst. In addition, the deactivation rate of 25N3ZA-673 was relatively slow in comparison to 25N3ZA-823 due to the presence of more reducible NiO. The formed nickel carbonyl species (Ni[CO]_x), which quickly decomposed at a higher reaction temperature, was closely related to the catalyst deactivation. Therefore, 25N3ZA-673 possessed much better stability at 593 K than that at 553 K.     

A comparative study on citrate sol-gel and combustion synthesis methods of CoAl2O4 spinel

CoAl₂O₄ spinel was successfully synthesized by combustion synthesis method using glycine and urea by 1:1 molar ratio as fuels and sol-gel process using citric acid as a chelating agent. The as-synthesized powders were calcined at desired temperatures to obtain CoAl₂O₄ spinel as a single phase. X-ray diffraction, thermogravimetric, and differential thermal analysis results revealed that the formation of CoAl₂O₄ spinel in combustion method needs 300°C higher temperatures than those of sol-gel. Scanning electron microscopy and transmission electron microscopy analysis results revealed that “sol-gel spinel” had nanometric particle size which was smaller than those of “combustion spinel.” Temperature programed reduction with hydrogen and Fourier transform infrared spectroscopy results declared that there was a little residual cobalt oxide in combustion spinel while there is no oxide resided in “sol-gel spinel.” Consequently, the sol-gel method has more benefit in synthesizing spinel with sulfate precursors than combustion.     

Characteristics of reaction and product microstructure during light calcination of magnesite in transport bed

A gas-heating laboratory transport bed was adopted to simulate the industrial transportbed reactor for flash calcination of magnesite, and a method based on TG analysis of a reacted sample was further developed to calculate the decomposition rate or conversion of its containing MgCO₃. The study investigated how the conversion and product reactivity as well as microstructure vary with reaction conditions including temperature, particle size and times of re-calcination for powder magnesite. Magnesite powder (<150 μm) calcination is a quick reaction that reaches 98% decomposition of its containing MgCO₃ in 1—2 s,corroborating the feasibility of magnesite flash-calcination in transport bed reactors. The coloration time given by the citric acid chromogenic method was 17—55 s and 294 s for the obtained products from transport and fixed beds, respectively. This proves the obviously higher activity and thus improved microstructure of the product from transport bed. During the calcination process, the MgO grain size of the product gradually increases, and the surface structure changes from loose and porous to dense and smooth. This structural change can be completed within a few seconds.     

锌阳极泥制取碳酸锰的研究

以电解锌产生的阳极泥为原料，用≤０．２４６ｍｍ褐煤粉作还原剂，过量５０％，焙烧温度７５０℃，时间８ｈ，此时９０％以上的四价锰还原为二价锰，还原后的焙烧粉经２．０４ｍｏｌ／Ｌ硫酸浸出，浸出液用硫化钠除重金属后用碳酸氢铵进行复分解反应，制得优质的工业碳酸锰，浸锰后的铅、银渣、配入硫化铅精矿后进行火法熔炼，制成粗铅（含银）。     

氯氧镁水泥喷射混凝土研究

对白云石控温煅烧、氯氧镁水泥反应机理、微观结构、抗水性等方面进行了分析研究，并进行了该水泥喷射混凝土的现场试验。试验表明，氯氧镁水泥喷射混凝土强度高、回弹率低（５．２８％）、粉尘小（１７ｍｇ／ｍ３）。经初步核算，氯氧镁水泥成本只相当于普通水泥成本的８０％。因此，将氯氧镁水泥用于喷射混凝土有着广阔的应用前景和显著的经济效益。