碳酸钙/铜渣复合固硫剂热解性能分析研究

首次分析研究铜渣作为添加剂,加入到碳酸钙中形成的碳酸钙/铜渣复合固硫剂的热解性能。通过XRD、DTA、BET、SEM分析可知,铜渣的加入能够改善碳酸钙/铜渣复合固硫剂的热解性能。热解分析表明:铜渣中的铁橄榄石(Fe2SiO4)、磁铁矿(Fe3O4)、白云石(CaMg(CO3)2)在高温下热解,产生对烟气脱硫有积极作用的Fe2O3、CaO、MgO、SiO2等物质。当铜渣加入量为10%(质量分数)时,碳酸钙/铜渣复合固硫剂的开始失重温度和失重时间比单独分析纯CaCO3的开始失重温度和失重时间分别降低85.9℃和提前13.3min,有利于脱硫反应的提前进行,延长了脱硫反应时间且降低了能耗;在煅烧温度为900℃时,碳酸钙/铜渣复合固硫剂比表面积达到最大值8.799m2/g,与单独分析纯CaCO3的比表面积5.00m2/g相比,其增幅达75.98%。     

煅烧工艺对SnO_2/Al_2O_3纳米纤维结构的影响

以聚乙烯吡咯烷酮(PVP)/氯化铝(AlCl_3)/结晶四氯化锡(SnCl4_·5H_2O)为原料,采用静电纺丝技术成功制备了有机无机复合纳米纤维膜,经过煅烧得到直径为150～800nm的SnO_2/Al_2O_3纳米纤维。XRD分析结果表明:随着煅烧温度的升高,SnO_2、Al_2O_3的晶粒尺寸增加;随着升温速率降低,其结晶越完整,晶粒排列更紧密;保温时间对结晶的影响不大。实验证实杂化纤维膜经900℃煅烧后,氯化锡完全转变成了四方红金石型结构的SnO_2,而氯化铝转变成比表面积最大、活性最高的γ-Al_2O_3。     

用包裹纳米复合粉体制备ZTA陶瓷

用非均匀成核法和液相共沉淀法相结合的方法制得ZrO2(3Y)包裹Al2O3纳米复合粉体,经干压成型,常压烧结制备ZTA复相陶瓷.通过XRD、TEM对粉料的物相组成和显微形貌进行表征,研究了包裹粉体中煅烧温度和ZrO2含量对烧结体的烧结性能和力学性能的影响.结果表明:随着前驱体粉料煅烧温度的升高,包裹后的Al2O3-ZrO2(3Y)复合陶瓷粉体比表面积降低,粒径变大;ZrO2含量为20wt.%的Al2O3-ZrO2(3Y)复合陶瓷粉体,经过1000℃锻烧后,干压成型制备的烧结样品的抗弯强度和断裂韧性分别高达454.9MPa和11.6MPa·m1/2,SEM观察结果表明烧结体结构致密.     

电纺ZnMn_2O_4纳米纤维的制备及其电化学性能研究

以聚乙烯吡咯烷酮(PVP)、Zn(CH3COO)2·2H2O、Mn(CH3COO)2·4H2O和乙醇为原料,采用静电纺丝法制备PVP/C4H6O4Zn/C4H12O8Mn复合纳米纤维,经过不同温度煅烧得到ZnMn_2O_4纳米纤维,将其运用于锂离子电池负极材料,探讨了煅烧温度对材料结构形貌和电化学性能的影响。利用热重、扫描电镜和X射线衍射等对其热解过程、形貌和晶型结构等进行了表征,通过恒流充放电测试研究煅烧温度对ZnMn_2O_4纳米纤维电化学性能的影响。结果表明:经高温煅烧后纤维形貌发生明显变化,出现了ZnMn_2O_4特征衍射峰,不同温度下煅烧处理后样品的首次放电比容量差异不大,但700℃处理后的样品具有较好的循环性能。     

稻壳灰-电石渣复合吸收剂的脱硫脱硝性能

SO₂和NO_x是水泥窑炉尾气中主要的大气污染物,减少其排放已经成为控制大气污染的主要途径。本工作尝试采用农业废渣稻壳灰和工业废渣电石渣配制复合吸收剂,在水泥熟料形成过程中实现脱硫脱硝。本工作研究了稻壳灰和电石渣掺配比(2∶5~18∶5,质量比)、反应温度(500~900 ℃)、氧气浓度(0%~3%)对复合吸收剂脱硫脱硝效率的影响。结果表明,稻壳灰和电石渣的配比为6∶5,掺入水泥生料中,在900 ℃、1%的氧气浓度条件下,脱硝率达到97%,脱硫率达99%。利用稻壳灰和电石渣这两种废渣配制复合吸收剂可以在水泥分解炉中有效脱除SO₂和NO_x。     

铁铈复合氧化物催化剂的制备及其性能研究

采用改进共沉淀法制备铁铈复合氧化物催化剂,通过L_(16)(4~5)正交实验确定最佳工艺条件。研究了不同煅烧温度对催化剂脱硝效率的影响,同时通过XRD、SEM、粒度和比表面积等方法对催化剂进行表征。结果表明,反应终点pH值是碳酸氢铵-氨水沉淀法制备铁铈催化剂最重要的影响因素,反应温度次之。脱硝实验表明,经400℃焙烧5h所制备的催化剂,其粒径较小,分布较宽,比表面积较大,SCR脱硝活性最高,在250℃脱硝活性为93.8%。     

基于非水解sol-gel法的碳热还原氮化合成氮化铝超细粉体

以无水氯化铝和异丙醚为原料,采用非水解溶胶-凝胶法制备出氧化铝凝胶。其经800℃煅烧才析出少量γ-Al2O3晶体,γ-Al2O3向α-Al2O3晶型转变在1200℃附近,经900℃煅烧后比表面积仍高达145m2/g,具有介孔结构。以该高活性氧化铝凝胶作为铝源,采用碳热还原氮化工艺合成氮化铝粉体。结果表明,氧化铝凝胶经300℃预煅烧,按n(C)/n(Al)=7.8与碳黑混合,在流量80mL/min高纯N2中,于1450℃还原氮化2h便可合成出平均粒径在400nm的高纯六方相AlN粉体。     

纳米Al2O3/ZrO2复合粉体的制备及表征

高性能的复合粉体是制备纳米复相陶瓷材料的关键.采用醇-水溶液加热法结合共沉淀过程制备纳米Al2O3/ZrO2复合粉体,研究了不同沉淀剂对粉体团聚的影响,利用透射电镜、X射线衍射、热重-差热分析、比表面积测定等技术对获得的纳米复合粉体进行了表征.结果表明:采用NH4HCO3作为沉淀剂可以得到几乎无团聚的碱式碳酸盐前驱物,该前驱物在煅烧过程中的物相变化显示四方相氧化锆(t-ZrO2)的形成温度大幅度地提高,同时在较低温度下生成了α-Al2O3,在1 100℃转变为t-ZrO2相和α-Al2O3相;粉体中两相颗粒分散良好、粒径一致、无硬团聚,其平均粒径为15～20 nm,比表面积为69.5 m2·g-1.     

共沉淀法制备Nd3+:Y2O3透明陶瓷

以Y2O3为基质材料,掺杂不同含量的Nd3+添加PEG和(NH4)2SO4为分散剂,采用共沉淀法制备出性能良好的Nd3+:Y2O3纳米粉.对前驱体和不同温度下煅烧后的粉体进行差热热重、X射线衍射、比表面积和透射电镜等分析.结果表明,前驱体产物为Y2(OH)5(NO3)·nH2O时,Nd3+完全固溶于Y2O3的立方晶格中,Nd3+:Y2O3粉体大小均匀,近似球形.随着煅烧温度的升高,颗粒逐渐长大,900℃煅烧2h后颗粒尺寸约为40～60nm;粉体在1700℃和真空度为1×10-3Pa条件下烧结6h得到的Nd3+:Y2O3透明陶瓷的透光率接近78%.     

不同晶型结构纳米ZrO_2的稳定化制备

采用共沉淀法制备了室温稳定存在的不同晶型纳米ZrO2粉体,用X射线衍射(XRD)、激光拉曼散射(Raman)、N2物理吸附、透射电镜(TEM)和动态光散射技术(DLS)等手段对其晶型结构、晶粒尺寸、比表面积和粒度分布进行了表征,研究了煅烧温度和改性剂掺杂量对晶型结构的影响。结果表明,无掺杂前驱体在850℃煅烧可得到m-ZrO2纳米粉体,比表面积为35.17 m2/g,晶粒尺寸为51.3nm;煅烧温度为600℃,Y2O3掺杂量为4.5%(摩尔分数)时纳米粉体的晶型结构为t-ZrO2,比表面积为39.01 m2/g,晶粒尺寸为19.2nm;煅烧温度为600℃,Y2O3掺杂量为8.5%时可得到比表面积为46.53 m2/g,晶粒尺寸为12.7 nm的c-ZrO2纳米粉体。     

低质高碳粉煤灰制备粉煤灰贝利特水泥及其特性研究

利用含碳量高、火山灰活性较低的堆存粉煤灰为原料,用水热合成-低温煅烧方法制备粉煤灰贝利特水泥,研究了配合料CaO掺量与在97℃±2℃下的蒸养时间、煅烧温度和煅烧时间对前驱物和粉煤灰贝利特水泥的组成及其基本物理力学性能的影响。结果表明:在97℃±2℃蒸养和800℃煅烧,粉煤灰中的莫来石和石英几乎不与CaO发生反应;800℃煅烧的粉煤灰贝利特水泥熟料中主要水硬性矿物为α’L-C_2S和C_(12)A_7,当煅烧温度达900℃或更高时,贝利特以活性较低的β-C2S存在,并且熟料中有水化活性很低的钙铝黄长石形成。CaO掺量为30%的石灰-粉煤灰配合料在97℃蒸养10h后经800℃煅烧1h,制得28d抗压强度达到30.2 MPa的粉煤灰贝利特水泥。粉煤灰贝利特水泥凝结快,可用于快修工程,但其需水量大,硬化浆体结构相对疏松,孔隙率较大。     

污泥-高钙煤系废物制备地聚合物的技术与性能

鉴于地聚合物是一种低碳排放且能源、资源消耗较少的新型胶凝材料,其制备技术倍受关注。采用热活化污泥和高钙煤系废物制备地聚合物,并与采用高钙粉煤灰和矸石制备地聚合物的反应机制与性能进行了对比分析,确定了制备污泥-高钙煤系废物地聚合物的最佳工艺参数。采用XRD、SEM、TG-DTA及FTIR等对制备的地聚合物的原料组成和性能进行了深入分析。研究表明: 经900℃焙烧45 min掺量为40%(＜50 μm)热活化污泥-煤系废物制备的地聚合物具有较好的抗压强度。无定形地聚合物胶凝包裹在球状粉煤灰颗粒周围,有类沸石矿物生成,Al—O/Si—O对称伸缩峰及Si—O—Si/Si—O—Al弯曲振动峰明显。     

Mechanical characteristics of clay structural ceramics containing coal fly ash

In this work, the mechanical characterization of ceramic products processed from red clay with different amounts of added coal fly ash was investigated. Coal fly ash produced by power plants is a waste material that constitutes an alternative source of minerals for the production of traditional building ceramics, as it is a complex mixture of several oxides such as SiO₂, Al₂O₃, CaO, Fe₂O₃, Na₂O, TiO₂, which are usually present in the composition of such ceramics. A powder technology and firing route was followed for the processing of the clay and coal fly ash based ceramics. Different proportions of waste (10, 25 and 50%, by weight) were added to red clay, and then the mixed powders were pressed to form compacts that were fired at a selected temperature in the range 850–1,150°C. The effects of waste content and of heating conditions on the microstructure and mechanical characteristics of the obtained materials were investigated. The density, porosity, water absorption, flexural strength, hardness and fracture toughness of the produced materials were evaluated. A comparison was made between the properties of the produced ceramics with those of traditional ceramic materials used in construction, e.g. floor or wall tiles, and it was observed that the clay based products with coal fly ash additions may be used in similar applications.     

The behaviour of Al in MSW incinerator fly ash during thermal treatment

Fly ash from municipal solid waste (MSW) incinerators contains leachable metals, including potentially hazardous heavy metals. The metal content of the fly ash can be reduced by thermal treatment, which vaporizes the volatile metal compounds. After heat treatment of fly ash at 1000 degrees C for 3 h, less metal was able to be leached from the thermally treated ash than from the ash without thermal treatment. Al and Cr were the exceptions. These metals were more soluble in the ash that had been thermally treated. This paper focuses on the leaching behaviour of Al only. Both simple and sequential extraction leaching tests showed that the leachable Al for the heat-treated fly ash is about twice that of the untreated fly ash. The sequential test further revealed that (i) the majority of the leachable Al is associated with Fe-Mn oxides in the fly ash, and (ii) most of the unleachable Al resides in the silicate matrices of the heat-treated and untreated fly ash. Pure chemicals, Al(2)O(3), CaO and CaCl(2), simulating the relevant ingredients in the fly ash, were used for studying their reactions at 1000 degrees C. The aluminum compounds were identified by X-ray Diffraction (XRD). Two new chemical phases produced by the thermal treatment were identified; Ca(AlO(2))(2) and 12CaO.7Al(2)O(3). Their formation suggests a mechanism whereby thermal treatment of fly ash would produce more soluble Al.     

Utilization of coal fly ash in the glass-ceramic production

Manufacturing the glass-ceramic has been proposed as a useful choice to recycle coal fly ash from power plants. In this work, a glass-ceramic of SiO2-Al2O3-Fe2O3-CaO family was synthesized by mixing 90 wt% of coal fly ash, from a power plant in west of China, with Na2O, and then melted at 1350 degrees C. The ceramization of the obtained glass was carried out at 770 degrees C for 2h. Esseneite and nepheline were found present as major crystal phases. The produced glass-ceramic exhibited good chemical durability as well as good mechanical properties. The toxicity characteristic leaching procedure (TCLP) method found that the glass-ceramic was non-hazardous.     

纳米CexGd1-xO2-δ复合氧化物的制备及表征

采用柠檬酸溶胶-凝胶法(Sol-Gel),以Ce(NO_3)_3·6H_2O、Gd_2O_3、柠檬酸为原料,制备纳米级Ce_xGd_(1-x)O_(2-δ)复合氧化物,对制得的样品进行X射线衍射、比表面、扫描电镜及能谱和透射电镜表征,研究样品的组成、晶粒大小、比表面积和样品形貌特征。结果表明,Ce_xGd_(1-x)O_(2-δ)复合氧化物在600℃和800℃焙烧后均形成均匀的面心立方CeO_2基固溶体和/或体心立方Gd_2O_3基固溶体。单组分Gd_2 O_3样品在800℃焙烧后形成具有体心立方的Gd_2O_3物相,经600℃焙烧后还同时含有43%(质量分数)的六方Gd_2O_2CO_3晶型。对于同一Gd~(3+)掺杂比例样品,焙烧温度越高,晶粒越大,比表面积越小;同一焙烧温度样品的晶粒尺寸随Gd~(3+)掺杂量增大先减小后增大,但均小于单组分CeO_2和Gd_2O_3,且Ce_(0.5)Gd_(0.5)O_(2-δ)样品晶粒最小。表明复合氧化物的形成提高了抗烧结能力,形成更多孔隙结构,使样品晶粒变小,比表面积变大,并且x=0.5为形成最小纳米级样品的最佳比例。     

Removal mechanism of phosphate from aqueous solution by fly ash

This work studied the effectiveness of fly ash in removing phosphate from aqueous solution and its related removal mechanism. The adsorption and precipitation of phosphate by fly ash were investigated separately in order to evaluate their role in the removal of phosphate. Results showed that the removal of phosphate by fly ash was rapid. The removal percentage of phosphate in the first 5min reached 68-96% of the maximum removal of phosphate by fly ash. The removal processes of phosphate by fly ash included a fast and large removal representing precipitation, then a slower and longer removal due to adsorption. The adsorption of phosphate on fly ash could be described well by Freundlich isotherm equation. The pH and Ca2+ concentration of fly ash suspension were decreased with the addition of phosphate, which suggests that calcium phosphate precipitation is a major mechanism of the phosphate removal. Comparison of the relative contribution of the adsorption and precipitation to the total removal of phosphate by fly ash showed that the adsorption accounted for 30-34% of the total removal of phosphate, depending on the content of CaO in fly ash. XRD patterns of the fly ash before and after phosphate adsorption revealed that phosphate salt (CaHPO4 x 2H2O) was formed in the adsorption process. Therefore, the removal of phosphate by fly ash can be attributed to the formation of phosphate precipitation as a brushite and the adsorption on hydroxylated oxides. The results suggested that the use of fly ash could be a promising solution to the removal of phosphate in the wastewater treatment and pollution control.     

复合纳米纤维静电纺丝法的制备及其磁性

以聚乙烯吡咯烷酮（PVP）和金属盐为原料,利用静电纺丝法成功制备出了摩尔比为1：1的SrTiO3-SrFe12O19磁电复合纳米纤维。并通过FT-IR,XRD,SEM和VSM等技术对纤维前驱体及其产物的结构、热处理产物的物相、形貌及磁性能进行了表征。结果表明,样品经900℃焙烧2h后,即可得到纯的SrTiO3和SrFe...     

Thermal activation on calcium silicate slag from high-alumina fly ash: a technical report

The fly ash with alumina composition from 45 to 55 % has been found in China in last 10 years, which attracts great attention from Chinese government and related alumina industry. Chinese government and its state-owned enterprises have successfully extracted the Al as alloy product from the high-alumina fly ash. However, to recycle the calcium silicate slag as residue from the Al industry is still undetermined. In this report, an innovative process is introduced to achieve the regional sustainability for the high-alumina fly ash industry, and it is found that the cementitious material composed of calcium silicate slag met with the mechanical requirements of 32.5 cement for road pavement. The chemical and mineral analysis show that the calcium silicate slag has high CaO content, which reaches up to 48.64 %. C₂S and C₃A are the dominant mineral phases by XRD analysis indicating its potential pozzolanic activity during the hydration process. Thermal activation from 200 to 900 °C was applied to enhance its pozzolanic activity for the calcium silicate slag and it proved that 600 °C is the optimal calcination temperature due to the decomposition of calcite and clay minerals. Also the mineral phase amorphization was also observed during the XRD analysis, which might also contribute to the enhanced pozzolanic properties at 600 °C. Although the designed cementitious material contains a large quantity of solid waste, none of the hazardous heavy metals exceed the EPA limits. This short article originally reported a promising direction for managing solid waste for Al industry and enhancing utilization efficiency for the enterprise internal solid wastes.     

Fabrication and Magnetic Property of One-dimensional SrTiO3/SrFe12O19 Composite Nanofibers by Electrospinning

The composite nanofibers of SrTiO3/SrFe12O19 with a molar ratio of 1:1 and diameter about 120 nm were prepared by electrospinning. Effects of calcination temperature on the formation, crystallite size, morphology and magnetic property were studied by infrared spectroscopy, X-ray diffraction, scanning electron microscopy and vibrating sample magnetometer. The binary phase of strontium ferrite and titanate was formed after being calcined at 900℃ for 2 h and the composite nanofibers were fabricated from nanograins of SrTiO3 about 24 nm and SrFe12O19 around 33 nm. The crystallite sizes for the nanofibers increase with increasing calcination temperature and the addition of SrTiO3 has an obvious suppression effect on SrFe12O19 grain growth. The specific saturation magnetization and remanence tend to increase with the crystallite size. With increasing calcination temperature from 900 to 1050℃, the coercivity increases initially, achieving a maximum value of 520.2 kA·m-1 at 950℃, and then shows a reduction tendency.