高硫铝土矿溶出过程中脱硫研究

研究了高硫型高品位铝土矿溶出过程的脱硫效果,考察了石灰添加量、溶出温度、苛性碱浓度和溶出时间对铝土矿中脱硫效果的影响。结果表明,在溶出高硫铝土矿时,脱硫效果最佳条件是:石灰添加量10%,温度245℃,脱硫时间70 min,碱液浓度240 g/L。此时,硫的溶出率仅为31.3%,同时又能保证氧化铝溶出率不低于81%。     

铝土矿高温溶出过程的性能研究

评述在高压溶出铝土矿过程中,加入石灰等添加剂可以改善氧化铝溶出的工艺过程,同时论述石灰添加量、溶出时间、溶出温度对氧化铝溶出率的影响,并对其作用机理进行了分析.     

拜耳法中石灰添加量对氧化铝溶出率的影响

在拜耳法高压溶出过程中，添加石灰可以改善氧化铝溶出的工艺过程，石灰添加量对氧化铝溶出率影响极大；最佳的石灰添加量可以获得较好的溶出效果。     

酸浸法提取粉煤灰中氧化铝溶出规律的研究

酸浸法是粉煤灰提铝的主要方法之一。介绍了一种提取粉煤灰中氧化铝的方法,用不同浓度的硫酸作溶剂,用氟化钠作助溶剂,通过一定配比加入粉煤灰中反应。实验结果表明,当温度为沸腾温度、氟化钠添加量为0、硫酸浓度为12 mol/L、溶出时间为150 min时,氧化铝的溶出率可达80.19%。该工艺反应在低温常压下进行,避免了高温烧结工艺,节约了能源,降低了成本,具有较高的实用价值。     

常压酸溶法制备聚合氯化铝的工艺研究

本实验以氢氧化铝、铝酸钙等为原料,采用常压酸解聚合二步法试验出优质的聚合氯化铝,并大大提高了氧化铝的溶出率。本实验着重考察不同酸溶试剂对氧化铝溶出率的影响,研究初始盐酸浓度、投加硫酸或投加混合酸对反应的影响。结果表明,初始盐酸浓度为30%左右为佳;在聚合反应时中添加混合酸显著提高了溶出率(100.7%)。制成的PAC产品的净水效果优于市售某知名品牌产品。     

二次铝灰中氧化铝碱溶研究

通过碱溶法从二次铝灰中提取氧化铝,探讨了固液比、碱液浓度、反应温度和反应时间等因素对氧化铝溶出率的影响。结果显示,在固液质量体积比为0.08 g/mL、碱液质量浓度为248 g/L、反应温度为250℃、反应时间为3 h和反应搅拌转速为400 r/min的实验条件下,氧化铝溶出率为98.6%;通过对二次铝灰中氧化铝溶出率、溶液苛性比和标准氧化铝-氧化钠-水系平衡图等指标进行分析,表明二次铝灰具有良好的碱溶性能。     

高硫铝土矿的焙烧预处理

采用回转窑对我国高硫铝土矿进行焙烧预处理,考察了焙烧温度、焙烧时间对矿物中硫含量及氧化铝溶出性能的影响,利用SEM和XRD技术对焙烧矿的微观形貌、晶型结构变化进行了分析,并对高硫矿脱硫机理和焙烧机理作了探讨. 结果表明,焙烧脱硫处理高硫型铝土矿是可行的,焙烧温度为750℃、焙烧时间为60 min时,焙烧矿中硫含量低于0.7%,达到我国 氧化铝生产的工业要求;焙烧矿在溶出温度220℃、溶出时间60 min的条件下,氧化铝溶出率达到97%以上.     

高硫高硅铝土矿焙烧–溶出性能研究

采用悬浮焙烧对高硫高硅铝土矿进行处理,考察了不同焙烧温度对矿石中硫含量的影响,通过X射线衍射和扫描电子显微镜分析了不同温度条件下焙烧对铝土矿中物相变化及微观形貌的影响,研究了焙烧温度对矿石中氧化铝溶出性能的影响。结果表明,悬浮焙烧温度600℃及以上时,能够使铝土矿硫化型硫含量降至0.2wt%以下。焙烧使铝土矿中高岭石相发生分解生成非晶态的偏高岭石,同时破坏矿颗粒致密结构,出现晶粒细化,但温度过高(650℃)会出现局部烧结现象。焙烧使一水硬铝石晶体破坏而活化,600℃时晶体破坏最完全,使600℃焙烧矿在相同溶出条件下溶出效果较原矿及其他焙烧矿优势明显,在溶出温度270℃、苛碱浓度245 g/L、石灰添加量14wt%的条件下,相对溶出率能达96%以上。     

高铁三水铝石型铝土矿在铝酸钠溶液中的溶出过程

在对某高铁三水铝石型铝土矿物相分析基础上,研究了其在不加钙的铝酸钠溶液中的溶出行为,考察了溶出液碱浓度、溶出温度和溶出时间对氧化铝溶出率的影响.结果表明,矿中Gibbsite形态的铝约占总铝量的70%,且嵌布于赤铁矿中;优化的溶出条件为,分子比3.0的铝酸钠溶液Na2O浓度为150 g/L、温度100℃、时间15 min,此时原矿中Al2O3溶出率达72%.该矿在低温低碱条件下的溶出过程受内扩散控制,计算的表观活化能为61.78 kJ/mol,溶出速率控制模式与表观活化能理论值不同可能与扩散形式相关.     

硫铝酸钙的氧化铝溶出性能

使用分析纯CaCO_3、Al_2O_3与CaSO_4·2H_2O配料,在1375℃、保温2 h的条件下合成了纯物相硫铝酸钙3CaO·3Al_2O_3·CaSO_4(C_4A_3S),对其物相组成和微观形貌进行了表征。并探究了碳碱浓度、苛碱浓度、溶出温度、溶出时间、粒度等因素对C_4A_3S氧化铝溶出性能的影响。结果表明:C_4A_3S的氧化铝溶出性能随着碳碱与苛碱浓度的增加先提高,之后趋于稳定。粒度越小,溶出率越高。与七铝酸十二钙12CaO·7Al_2O_3(C_(12)A_7)相比,C_4A_3S的孔洞状结构使其氧化铝更易溶出,在10 min时氧化铝溶出率即达到98%以上,且溶出所需的碳碱浓度与溶出温度均低于C_(12)A_7。在最佳条件:碳碱80 g·L~(-1)、苛碱10 g·L~(-1)、溶出温度80℃、溶出时间10 min下,C_4A_3S的氧化铝溶出率为98.76%。     

高铝煤矸石铝硅分级提取实验研究

分级研究了热活化条件下高铝煤矸石在盐酸和氢氧化钠溶液中的铝硅溶出行为。采用X射线衍射仪（XRD）、扫描电镜（SEM）和比表面积测定仪（BET）对煤矸石试样做了表征分析。通过正交实验分析了反应温度、反应时间、初始酸碱浓度和固液比对热活化处理后高铝煤矸石中Al2O3和酸浸渣SiO2溶出率的影响。结果表明：酸浸溶出Al2O3反应过程中,固液质量比和酸浸时间对溶出率的影响最为显著,酸浸过程的最优工艺条件：初始盐酸质量分数为20%、酸浸温度为90 ℃、酸浸时间为2.5 h、固液质量比为1∶6,在此条件下,Al2O3的浸取率达82.95%;强碱溶解酸浸渣溶出SiO2反应过程最优工艺条件：碱溶温度为95 ℃、碱溶时间为2.0 h、NaOH质量分数为20%、固液质量比为1∶10,在此条件下SiO2溶出率为69.74%,碱溶温度和碱液浓度对溶出率的影响最为显著。     

Hydration and properties of novel blended cements based on cement kiln dust and blast furnace slag

The aim of the present paper is to address the key technical issues pertaining to the utilization of cement kiln dust (CKD) as an activator for ground granulated blast furnace slag (GGBFS) to create nonconventional cementitious binders for concrete. The relatively high alkaline content of CKD is the predominant factor preventing its recycling in cement manufacture. However, it was observed that depending on the water-soluble alkali and sulfate compounds, CKD could provide the environment necessary to activate latent hydraulic materials such as GGBFS. Binary blends containing slag and CKDs from different sources were characterized and compared in terms of the rates of heat evolution and strength development, hydration products, and time of initial setting. A study of the effects of the influencing factors in terms of soluble alkali content, particle size, and free lime content was undertaken. The results confirm the dependence of the dissolution rate of slag on the alkalinity of the reacting system, and the importance of the optimum lime content on the rate of strength gain.     

Kinetics of the dissolution behaviour of anodic oxide films on niobium in NaOH solutions

The dissolution behaviour of the anodized niobium electrode in NaOH solutions was investigated as a function of alkali concentration, formation voltage, formation current density and temperature using potential and impedance measurements. The rate of dissolution is dependent on the alkali concentration. In dilute NaOH solutions (1 N) the anodic oxide film formed in 0.5 M H₂SO₄ is reasonably stable. On the other hand, at higher concentrations of NaOH (2 M), the anodized electrode is subject to continuous dissolution depending on the alkali concentration. Also, the dissolution process is considerably affected by temperature; at temperatures greater than 320 K the oxide film is destroyed in less than 30 min. The results show that the current density used during the formation of the oxide film has no effect on its dissolution rate.     

常压石灰法处理烧结法赤泥脱碱及其机理研究

采用石灰（CaO）作为脱碱剂处理烧结法赤泥,研究了反应温度、反应时间、脱碱剂添加量、液固比等因素对赤泥中钾、钠溶出率等碱脱除效果的影响,分析了石灰处理赤泥的脱碱机理。结果表明：温度升高、反应时间延长、石灰掺量增加以及液固比增大均能提高赤泥的脱碱效果,其中尤以反应时间和石灰掺量的影响效果更显著。添加石灰处理烧结法赤泥的脱碱机理是部分方钠石（Na₈Al₆Si₆O₂₄CO₃）中的2个Na⁺被1个Ca²⁺置换出,生成了更难溶的钙霞石［Na₆CaAl₆Si₆（CO₃）O₂₄·2H₂O］。     

Tentative modelling of spray-dry scrubbing of SO2

A 0.5 MW spray-dry scrubbing FGD pilot plant was used in the study of spray dryer performance over a wide range of operating conditions. Experimental findings were compared with a spray dryer model. During operation with large excesses of lime, the SO₂ absorption was limited by gas phase diffusion. At operation with a shortage of lime, the rate limiting step was the dissolution rate of lime. In addition, the flow regime in a spray dryer can be best described as well mixed. The SO₂ level in the flue gas was found to exert no direct effect on the efficiency of SO₂ removal. The observed effects are attributed solely to the changes in the drying process, due to the inter-dependence of slurry composition and SO₂ concentration.     

水-甲醇混合溶剂中煤的电化学脱硫研究

对贵州六枝高硫煤在水 -甲醇混合溶剂中的碱性电解脱硫规律进行了研究。考察了温度、煤浆浓度、碱浓度及混合溶剂组成等因素对脱硫率的影响。     

水溶性聚酯合成及其溶解特性研究

研究了SIPM用量和聚合反应条件对酯交换反应速度、产物分子质量的影响,考察了合成产物的结构和碱溶解特性。结果表明:SIPM用量增加,酯交换反应速度下降,当SIPM质量分数由8%增加到12%时,反应速度明显下降,产物分子质量随聚合反应体系余压减小和SIPM用量降低而增大,得到的水溶性聚酯有很好的碱可溶性,减量率随NaOH浓度增加,碱解时间延长,温度提高而增大。     

Influence of viscosity and composition of alkali borosilicate lead-free frit on its reaction with hematite,and the color control of red overglaze enamels

Inspired by the ion diffusion at the interface between the red glaze and glaze layers, which was confirmed by the study of overglaze painting on porcelain test pieces, we developed frits with compositions in which a lime glaze was systematically added to a lead-free multicomponent alkali borosilicate glass frit. When the mixed powder of the frit and hematite was heat-treated, the excessive reaction with hematite was suppressed as the lime glaze content increased, due to the increase of the frit viscosity. The dissolution of hematite was suppressed in the sample with the same viscosity at a higher heat treatment temperature, i.e., with a higher lime glaze content, confirming that the composition of the frit strongly affects the dissolution of hematite. We attempted to improve the chroma of lime-glaze-added samples, and the highest chroma in this system was achieved by adjusting the amount of initial hematite and heat treatment temperature.     

碳酸钙渣悬浮态煅烧试验及工业应用研究

碳酸钙渣是利用磷石膏制备硫酸铵时排放出的废渣,其主要矿物成分是碳酸钙,通过煅烧可以得到高活性石灰进行再利用。利用高固气比悬浮态煅烧技术,对碳酸钙渣快速煅烧工艺进行了中试试验,得到表观分解率为95%以上的煅烧产品,且表现出较高的活性;在此基础上,与贵州瓮福磷肥厂合作采用高固气比悬浮煅烧-快速冷却技术建成一条碳酸钙渣制备活性石灰的工业试验线,产品中氧化钙的质量分数最高可达到59%,碳酸钙分解率在97.7%以上,产品的活性高,多数集中在160~180 s。系统烧成热耗为4 402 kJ/kg,能耗及产品质量均优于传统工艺。