Recovery of molybdenum from fly ash by gibbsite

The effectiveness of gibbsite (GB), an amorphous aluminum oxide, for the recovery of Mo(VI) from eluates of fly ash of two coal-fired thermal power stations and of roof tile waste was investigated. Upon the qualitative analysis of an eluate of fly ash, 16 elements were detected. Greater amounts of these elements were eluted under acidic conditions (pH 2) than from the neutral or basic eluate of fly ash. GB was used for the adsorption of Mo(VI). Equilibrium adsorption was reached within 1?min. Optimal solution acidity for the adsorption of Mo(VI) onto GB400 (calcined at 400°C) was pH 2. The main adsorption mechanism was ion exchange with a number of hydroxyl groups of GB400. For repeated ad- and desorption of Mo(VI), GB400 could be used at least four times and the recovery percentage of Mo(VI) with sodium hydroxide solution as eluent surpassed 90%. Our results showed that GB400 was very effective for the recovery of Mo(VI) from fly ash.     

Chemical Behaviour of Calcium in Stabilized Oil Ash Reef Blocks After Five Years in the Ocean

Abstract

Reef blocks made from stabilized oil ash were taken from the sea after five years in the ocean to examine the chemical behaviour of calcium. Experiments included (1) determination of the calcium leaching rate and a comparison with the rate for unexposed blocks to test the validity of a diffusion model for predicting long term (5 years) leaching rates, (2) determination of the effect of biological cover (shell) on the leaching rate, (3) determination of the leaching rate of the core of exposed reef blocks, (4) determination of the calcium content in ‘ring areas’ - regions of discoloration observed in sectioned exposed reef blocks, and (5) determination of the leachable fraction of the total calcium in exposed reef blocks. Results showed the presence of a pronounced calcium discontinuity zone located 3–7 cm from the outside surface of the reef blocks. Cumulated calcium release rates ranged from 2.81–3.14 μmol cm^?2 day^?1 for original unexposed reef blocks and the core of exposed (in the ocean for five years) blocks, respectively, to 0.47–0.50 μmol cm^?2 day^?1 for outside (facing sea water) surfaces of exposed reef blocks. Tank leaching studies also showed that the presence or absence of hard biological cover (shells) had little or no effect on the calcium release rate. the diffusion model normally used in modelling the chemical behaviour of calcium cannot be used to predict the long term (five years) leaching of calcium. the core of the exposed blocks released calcium at a rate similar to new, unexposed reef block material. Overall, it appears that the calcium discontinuity zone is probably responsible for restricting the release of calcium and hence the failure of the diffusion model.     

Leaching Characteristics of Lead and Cadmium From Waste-To-Energy Residues in Sea Water

Laboratory studies were conducted to determine leaching characteristics of waste-to-energy (WTE) residues in sea water to provide initial evaluation on the potential impact of WTE residues on the marine environment. Both loose and stabilized WTE residues were investigated for the leachability of lead (Pb) and cadmium (Cd) in sea water. Results of the study showed that loose WTE fly ash was very reactive in sea water; release of Pb and Cd occurred immediately (<0.5 hr) after the ash came in contact with sea water. Stabilization (treated with Portland cement and other additives), however, significantly reduced leaching of Cd and Pb. While ocean disposal of untreated WTE residues would not be advisable, utilization of stabilized WTE residues for beneficial uses should be investigated.     

内置预分离复合式飞灰过滤器的开发与应用

针对飞灰过滤器除尘压降高、反吹清灰频繁、过滤元件破损、使用寿命短和大型化受到限制等问题,开发了内置旋风预分离复合式飞灰过滤器,并在工业装置上进行了应用,应用结果表明:过滤器压降明显降低、旋风分离器压降满足系统要求、延长了陶瓷滤芯的使用寿命、减少了因飞灰过滤器故障造成整个装置停车,同时,可带来直接经济效益约1 709万元/a、间接经济效益超过5 000万元。     

矿化垃圾的改良及其在草坪生产中的应用研究

在草坪生产过程中,以生活垃圾填埋场矿化垃圾作为农田土的替代物,既实现了矿化垃圾的资源化及垃圾填埋场的可持续利用,又避免了常规草坪生产中对农田的破坏。以粉煤灰为改良剂,对矿化垃圾进行改良,利用改良后的矿化垃圾为基质培养高羊茅。通过测试改良矿化垃圾的保水率、透水率以及高羊茅的株高、发芽率、鲜重、叶绿素等指标,分析了改良矿化垃圾作为高羊茅草坪生产用土的可行性。结果表明,在土壤指标方面,改良后的矿化垃圾保水率与透水率均有所下降,接近于普通农田土的水平;其pH值没有显著变化;但是可溶性盐含量明显降低,其中5∶5组可溶性盐含量降低了51.8%,改良最为明显。在植物指标方面,各改良组的株高均明显优于矿化垃圾组,其中4∶6组高羊茅的株高达到了改良前的117%;各改良组高羊茅的发芽率也明显高于改良前,其中4∶6组其发芽率达到了改良前的122%。改良后的矿化垃圾的物理、化学特性有明显改善,接近于农田土,可以替代农田土作为草坪的培养土。     

粉煤灰-煤矸石基胶结充填材料制备与性能研究

为了解决我国煤矿采空区地表沉陷以及"三下"压煤资源浪费的问题,提出以粉煤灰-水泥熟料-脱硫石膏复合胶凝材料为胶结材,原状粉煤灰为细骨料,破碎后的煤矸石为粗骨料制备新型煤矿开采胶结充填材料。依据正交试验结果和各因素影响规律趋势图,确定充填材料的优化配合比。研究结果表明,适当增大水泥熟料掺量可缩短材料初凝时间,减小水胶比能使材料强度显著提高,而材料坍落度可通过选取适宜的浆体中的固体质量分数和灰矸比来有效调节,当胶凝材料中水泥含量为15%,脱硫石膏含量为8%,水胶比为2,灰矸比为2∶3,浆体中的固体质量分数为70%时,充填材料性能可达到最佳。通过试验优选材料各项参数,工业废弃物可以用来制备高质量的胶结充填材料。     

燃煤锅炉房灰水系统阻垢对策探讨

对锅炉房灰水系统结垢问题进行分析,找出结垢的原因,采用以新型高效阻垢剂为主的综合方法进行防垢试验取得成功,并获得较好的经济效益。     

添加剂对垃圾焚烧飞灰熔融过程二噁分解的影响

为了研究添加剂对垃圾飞灰熔融处理过程中二噁(口英)分解特性的影响,选择碱性氧化物CaO和液体陶瓷(LC)2种添加剂,改变温度、气氛和熔融时间研究2种添加剂对二噁(口英)分解率的影响.研究表明CaO对二噁(口英)分解影响随气氛不同而改变,氧化气氛下,加入CaO使二噁(口英)的分解率略微降低,而在还原气氛下则会使二噁(口英)分解率升高.液体陶瓷添加剂对熔融过程二噁(口英)分解有显著影响.1400℃时,随着LC添加比例由0增加到10%,二噁(口英)分解率则从99.997%升高到100%.同时加入10%的LC可以使二噁(口英)的完全分解温度由无添加剂时的1460℃降低至1100℃.     

环保型原油族组分-溶剂分离器的研制

研制的环保型原油族组分-溶剂分离器是一种非常规玻璃蒸馏装置,在玻璃器皿内部加热多个原油族组分的有机溶液,在分离原油族组分和有毒溶剂的同时回收了溶剂,使室内空气质量达到国家标准,减少了空气污染.     

统计学在垃圾焚烧飞灰浸提液重金属检测准确性研究中的应用

为提高复杂基体重金属检测准确性,在使用电感耦合等离子体发射光谱法检测生活垃圾焚烧飞灰浸提液时,进行标准曲线法、标准加入法和内标法3种定量校准方法比对。3种方法报出结果经过加标回收率换算后的样品原值具有明显一致性,使用统计学方差齐性和单因素方差分析验证了该一致性成立,表明内标法的精密度和准确度与标准曲线法、标准加入法无显著性差别。以3种方法样品原值的算数平均值作为样品最佳估计值评价各方法实际报出结果准确性,标准加入法准确性最好;稀释后的样品内标法加标回收率明显优于标准规定,受稀释倍数影响不大,工作效率高,满足HJ 781—2016质控要求,建议可作为该标准的补充;建议批量样品检测时优先采用内标法。3种方法样品原值一致性的验证,有助于执法、科研中对于复杂基体重金属物质含量的准确判断。