赤泥多孔材料负载微生物去除苯酚

以赤泥等工业废弃物为原料制备了一种多孔材料,采用酸改性、碱改性、氧氯化锆改性3种方法进行表面改性,在表面负载假单胞菌,用于去除污水中的苯酚。结果表明:在1200℃下烧结多孔材料,孔隙率可以达到80%,孔隙大小控制在50～100μm;氧氯化锆改性后的多孔材料负载假单胞菌的能力强;去除苯酚的主要影响因素为苯酚初始浓度和pH值,在pH值为5～6、苯酚初始浓度为40mg/L的条件下去除能力最强,可以达到80%。     

Photocatalytic properties of ZnO nanoparticle coating on porous ceramic substrates with varying porosities produced from fly ash and red mud

In order to improve filtering efficacy, nanoparticles are often deposited as photocatalytic degrading agents onto porous ceramics. This study aimed to deposit ZnO nanoparticles on ceramic substrates produced from fly ash and red mud with adjustable porosity and investigate their photocatalytic properties. To achieve this goal, at first porous ceramics were produced and sintered at various temperature/time intervals. It was observed that sintering at 800°C for 120 min provided a proper structure and porosity. In addition, MgO replacement with MgCO₃ lowered the water absorption of the samples from 25.63% to 11.45%. The samples were then coated with ZnO nanoparticles using the sol–gel method and the ZnO structures obtained were micron-sized plates. It was observed that increasing porosity increased the ZnO amount and accordingly the photocatalytic properties of the products. During the adsorption tests conducted in the dark, the coated ceramic samples were stained with MB with a maximum MB adsorption ratio of ∼14%. On the other hand, no visible MB stain was observed on the samples that were exposed to UV irradiation, and the MB removal after the UV irradiation was 93.6%; therefore, it was concluded that the dominant MB removal mechanism was photocatalytic.     

Novel glass ceramic foams materials based on red mud

Glass ceramic foams were prepared using red mud and fly ash with added CaCO₃ as foaming agents. The aim of the present work was to investigate the possibility of adding red mud, an alkaline leaching waste, in the raw material for the preparation of glass ceramic foams. The results of mineralogical analyses as well as the microscopic examination showed that the use of the red mud affect the mineralogical characteristics and structures of the as produced foams. The influence of amount of red mud on the bulk density and compressive strength of samples was further evaluated. The experimental results showed that relatively low bulk density foams (0.33–0.41 g/cm³) could be obtained by using low sintering temperature (760–840 °C) when the red mud/fly ash ratio does not exceed 40:60. The reduction of sintering temperature or, above all, the reduction of the holding time, was found to limit the coalescence and significantly improve the compressive strength of the foams (0.33–2.74 MPa).     

Preparation and characterization of porous anorthite ceramics from red mud and fly ash

The porous anorthite ceramics with high porosity, good mechanical strength and low heat conductivity were prepared using red mud and fly ash as raw materials via the pore forming method. The effects of sintering temperature and fly ash on phase evolution, densification, compressive strength, thermal conductivity and microstructure of the ceramic materials were investigated. The results showed that the compressive strength of the porous ceramics had an obvious improvement with the increase in fly ash, and the densification and heat conductivity decreased firstly and then increased. In particular, specimen S2 containing 30 wt% red mud and 40 wt% fly ash sintered at 1150°C had the better performances. It had the water absorption of 18.18%, open porosity of 38.52%, bulk density of 1.29 g/cm³, compressive strength of 42.46 MPa, and heat conductivity of 1.24 W/m·K. X-ray diffraction analysis indicated that mullite, anorthite, α-quartz, and diopside ferrian were the dominant phases in the specimens. Scanning electron microscopy micrographs illustrated that plenty of open pores with strip shape and closed pores with axiolitic shape existed in the specimens. Furthermore, the existence of mullite could prevent crack propagation to enhance the energy of inter-granular fracture. It endowed the porous anorthite ceramics with high porosity, good compressive strength, and low heat conductivity.     

改性赤泥颗粒吸附剂的性质及机理研究

采用焙烧法对赤泥进行活化处理,将其与粉煤灰、碳酸氢钠和膨润土按照质量比为16∶2∶1∶3制成改性赤泥颗粒,该改性赤泥颗粒破碎率与磨损率之和为0.2%。将其作为吸附剂,采用静态吸附试验方法研究了该改性赤泥颗粒吸附剂对模拟含磷废水除磷的一般规律,在磷的质量浓度为3~100 mg/L条件下,考察了反应时间、初始磷浓度、投加量等因素对改性赤泥颗粒吸附效果的影响,经过计算得出其饱和吸附量。结果表明,改性赤泥颗粒对磷的去除效果在反应8 h后趋于稳定,其最佳投加量为5 g/L,改性赤泥颗粒的饱和吸附量为56.2 mg/g。     

逆流浸取法回收赤泥中的碱

赤泥脱碱现有的方法不足主要表现在：酸法或碱法脱碱会耗费大量的酸或碱,使脱碱成本偏高;简单水洗法脱碱时,副产品中碱浓度较低,不能实现赤泥与碱的综合利用。本文以阴离子型聚丙烯酰胺为絮凝剂,水为浸取剂,采用五级逆流浸取法对赤泥中碱的回收利用进行研究,考察了温度、液固比、浸取速度等因素对碱的浸出率及浓度的影响,得出碱的浸出率与浓度随温度、液固比、浸取速度等因素的变化规律,确定最佳浸取条件为：温度70℃,液固比3∶1,浸取速度15mL/min,在此条件下赤泥中碱的浸出率达89.18%,浓度达到20.38g/L。此方法不仅能将赤泥中的碱有效脱除,同时得到浓度较高的碱溶液,实现赤泥与碱的综合利用。     

赤泥碱回收的初步研究

赤泥是氧化铝冶炼工业生产过程中排放的固体废弃物,它属于强碱废渣,是一种严重的碱性污染源。采用热水及氧化钙水浴法对强碱性赤泥进行脱碱过滤洗涤。实验结果表明,添加氧化钙后赤泥滤液中碱浓度明显高于未添加氧化钙的,且随氧化钙添加量的增加,赤泥滤液中的碱浓度升高。赤泥中氧化钙的添加量为5%（质量分数）时,滤渣水洗3次回收碱的效率最高,回收的碱量接近回收总量的3/4。水洗各组赤泥的洗涤液的pH改变不大,均只降低了约0.5。各组水洗回收碱的回收效率与前期反应处理方式的关系不大,回收率主要受洗涤次数的影响。     

赤泥/木质素共热解制备复合吸附材料及其性能

炼铝工业产生的赤泥废渣以不合理的方式处置,会造成严重的环境污染和资源浪费。赤泥中富含的铁元素以Fe₂O₃的形式存在,不利于铁资源回收,可通过还原方式制取磁性材料用于重金属离子的去除。基于此,本研究采用碳热还原法耦合赤泥与木质素制备一种复合吸附材料。系统探究还原温度、还原时间、还原剂用量对还原效果的影响,并开展铅离子吸附实验。研究表明,通过与烟煤还原赤泥对比得出木质素还原赤泥最佳工艺参数：还原温度625℃、还原时间30min、木质素与赤泥质量比为1∶1;GC对共热解气体产物进行分析得出赤泥的引入能够提高氢气产量;GC-MS对共热解液体产物进行分析得出木质素/赤泥共热解能够提升芳烃类化合物产量;吸附实验得出制备的复合材料能够有效去除水溶液中的铅离子。通过耦合赤泥、木质素残渣两种废弃物制备复合吸附材料,能够响应国家环保政策,具备潜在的经济、能源、环境效益。     

Dissolution kinetics of cerium from red mud

Leaching kinetics of rare earth element (REE) cerium (Ce) from red mud was investigated using different shrinking core models. The effect of various pertinent parameters such as acid concentration, liquid–solid ratio (LS), average particle size (PS), temperature and leaching time on the leaching efficiency was studied. The maximum recovery of 70.32% was obtained for 2 M HCl solution and an LS of 20:1 v/v. It was observed that the leaching process was limited by diffusion within the porous ash layer of the solid, thus making it ash diffusion controlled. The apparent activation energy was 11.38 kJ/mol, and the Arrhenius constant was 3.36 min?1.     

Preparation and performance of ceramic filter material by recovered silicon dioxide as major leached component from red mud

In this study, a new ceramic filter material was prepared by recovering red mud from red mud at atmospheric pressure. The primary objective of this research was to investigate the effects of SiO₂ quantity and sintering temperature (ST) on the porosity, stability, microstructure, and performance of the resulting materials. The results demonstrated that after a two-step leaching process with 3 M HCl and 90% sulfuric acid, the recovery of SiO₂ from red mud exceeded 80%. The SiO₂ extracted from red mud was used as the main material and mixed with other materials including Na-bentonite, limestone and pulverized coal at a ratio of 65:25:8:2, resulting in a ceramic filter material with favorable chemical stability, high strength, and nontoxicity. The enhanced surface activity of the material can be attributed to the abundant Si-OH groups, which enable it suitable for the ammonia nitrogen removal from drinking water. Overall, silicon dioxide extracted from red mud will help solve the stockpile and pollution problems of it in China.     

赤泥水浸脱碱实验及动力学研究

赤泥是一种碱性污染物,强碱性是制约其综合利用的关键因素。进行了拜耳法赤泥水浸脱碱实验及动力学研究,实验结果表明：赤泥在水浸次数为4次、液固体积质量比为9 mL/g、反应温度为90 ℃和反应时间为60 min的条件下,赤泥的脱碱率可达71%。采用未反应收缩核模型对水浸脱碱数据进行线性拟合,动力学分析表明：活化焙烧后赤泥的水浸脱碱过程受扩散步骤控制,线性相关系数大于0.97,表观活化能为11.72 kJ/mol。     

铝厂赤泥中提钪技术的研究

根据赤泥的基本性质和综合处理的现状,研究提高赤泥中稀有金属钪回收率。采用逆流循环浸出赤泥,通过调节浸出过程中各影响因素,最佳工艺条件为：硫酸浓度900～1000g／L,浸出温度90℃以上,液固比5：1,浸出时间4h,钪的综合回收率达到85％以上。     

水洗处理赤泥初步脱碱

赤泥是氧化铝冶炼工业生产过程中排放的固体废弃物,是一种严重的碱性污染源。实验采用不同温度（20、55、75、95 ℃）的水分别对强碱性赤泥进行洗涤。结果表明,首次洗涤所得洗涤液的质量浓度较高,6次洗涤液的平均质量浓度在2.44~2.72 g/L,其中冷水洗涤赤泥所得的溶液质量浓度最高。每次洗涤得到的洗涤液的pH变化不大。不同温度的水洗涤赤泥,回收碱的效率相差不大,前3次洗涤碱的回收量占总量的70%以上。其中,冷水洗涤赤泥回收碱的质量最多。经过6次洗涤后,每克赤泥中最终回收的氢氧化钠的质量最高达8.18 mg。     

Cyclohexanethiol separation from kerosene oil by red mud

The transfer of cyclohexanethiol from kerosene oil to unconventional adsorbent, red mud and the influence of variation in agitation rate, concentration and temperature on separation by adsorption technique has been investigated. The maximum transportation of sulfur compound from oil containing 730.67 mg dm^?3 (0.025% by weight sulfur) of cyclohexanethiol was noted at 45°C. The adsorption follows first order kinetics and is a diffusion controlled process. The applicability of Langmuir isotherm indicates monolayer coverage of sulfur on the outer interface of red mud. Calcination of red mud and thermodynamic parameters suggest the favorable separation of cyclohexanethiol from kerosene oil by adsorption.     

铁泥氧化制备颜料铁红的研究

以工业废渣铁泥为原料,经拌酸氧化制备铁红颜料,探讨了酸的种类、浓度及用量和氧化温度及时间对产品质量的影响。结果表明,较佳的工艺条件为:硫酸浓度60%,硫酸与铁泥质量比1∶1.2,氧化温度800℃,氧化时间2.0 h,得铁红产品,质量符合油漆、涂料等对铁红颜料的要求。     

赤泥中铁的微波还原性及其热力学分析

利用氧化铝厂拜尔法赤泥,通过配入复合添加剂并利用炭黑作吸波剂及还原剂,采用微波碳热直接还原工艺,对赤泥中铁成分的回收效果做了研究,采用XRD、SEM和EDS等手段对分离出的铁相及熔渣的成分加以分析。结果表明,该方法可以实现铁相从熔渣相中的有效分离,还原出的Fe质量分数达到77.37%。还从热力学的角度探讨了实验中复合添加剂的掺入对降低该固相反应温度的作用原理,为赤泥的高效综合利用提供了新的思路。     

高效回收赤泥中铁的研究

采用氯化铵干法对赤泥进行了除铁的实验,探究了不同的工艺条件对铁回收率的影响,在最佳工艺条件下:赤泥与氯化铵配比1∶0.65,焙烧温度400℃,焙烧时间120min,铁的回收率达到了80%.     

天然碱工业伴生废渣的再生循环利用

在以天然碱为原料生产重质纯碱时,伴生大量碱性废渣(俗称“苛化泥”),此废渣堆放或坑埋．碱化土壤,污染环境和空气,若用大型回转窑煅烧处理,成本高不经济。本文介绍了用六段隧道窑技术将该废渣再生循环利用的新方法。     

烧结法赤泥用于废水除磷的研究

采用不同浓度的双氧水活化赤泥,用静态吸附法研究了不同活化赤泥对于废水中磷的吸附性能,考察了处理温度、时间、pH等因素对脱磷的影响。采用热分析、XRD、FT-IR等手段对活化前后的赤泥进行了表征分析。结果表明：经活化处理的赤泥对磷的吸附能力较未活化的赤泥有了明显的提高,经质量分数为15%双氧水处理,再经700 ℃热处理的赤泥对磷的饱和吸附量可达252.40 mg/g。实验证明赤泥对磷的吸附符合Langmuir吸附模型,属于单分子层吸附。将经过活化的赤泥用于废水中磷的脱除,具有较好的应用前景。