Enhance Cyanide Recovery by UsingAir‐Sparged Hydrocyclone

Human health and environmental concerns dictate that industrial processes be improved or replaced. Recovery or recycling is an important activity that allows cyanide residue from the industrial processes to be re‐used, reducing its production cost and disposal problems. In this regard, the air‐sparged hydrocyclone (ASH) has been used as a reactor for the treatment of cyanide solutions for cyanide recycling by acidification/volatilization using the Mexican modification of the Mills‐Crowe process. Aqueous cyanide‐ion concentration can be reduced from 250 ppm to below 20 ppm in the ASH with recoveries greater than 80 % in a single stage.     

循环流液相等电聚焦方法及应用研究

利用循环流液相等电聚焦技术，对Ｈｂ、Ｃｙｔ．Ｃ和ＢＳＡ混合物进行分离，对ＲＮａｓｅＡ粗制品进行精制。该方法上样量大，活性回收好。对聚焦过程中扩散、对流和电渗的影响进行了讨论。     

Characterization of sintered coal fly ashes

Çan, Çatala?z?, Seyitömer and Af?in-Elbistan thermal power plant fly ashes were used to investigate the sintering behavior of fly ashes. For this purpose, coal fly ash samples were sintered to form ceramic materials without the addition of any inorganic additives or organic binders. In sample preparation, 1.5 g of fly ash was mixed in a mortar with water. Fly ash samples were uniaxially pressed at 40 MPa to achieve a reasonable strength. The powder compacts were sintered in air. X-ray diffraction analysis revealed that quartz (SiO₂), mullite (Al₆Si₂O₁₃), anorthite (CaAl₂Si₂O₈), gehlenite (Ca₂Al₂SiO₇) and wollastonite (CaSiO₃) phases occurred in the sintered samples. Scanning electron microscopy investigations were conducted on the sintered coal fly ash samples to investigate the microstructural evolution of the samples. Different crystalline structures were observed in the sintered samples. The sintered samples were obtained having high density, low water adsorption and porosity values. Higher Al₂O₃ + SiO₂ contents caused to better properties in the sintered materials.     

用废聚苯乙烯泡沫塑料制备胶粘剂的研究

利用废弃聚苯乙烯泡沫塑料(EPC),加入甲苯、丙酮和乙酸乙酯作溶剂,溶质(EPS)与溶剂之比为0.357时,测得胶粘剂的强度较高;用邻苯二甲酸二丁酯作为改性剂,改性剂加入量体积为7%时,胶液强度达到最高,可加入甘油调整胶液的强度和粘度.     

高掺量赤泥-粉煤灰微晶玻璃研究

赤泥是氧化铝生产中排放的碱性废渣,粉煤灰是燃煤电厂排放的高SiO2含量废渣.综合利用两种废渣制备高性能的微晶玻璃材料,控制SiO2含量在31%～44%,CaO含量在25%～31%,两种废渣总吃渣量能够达到90wt%以上,具有显著经济效益和环境效益.     

Neutralizing capacity of bottom ash from municipal solid waste incineration of different particle size

This study measures the neutralizing capacity of bottom ash from municipal solid waste incineration of different particle sizes. We examine the effect of particle size on the weathering process, a method popularly used for stabilization of heavy metals in incineration of bottom ash. The distribution of particle sizes in municipal solid waste incineration bottom ash is rather broad, ranging from fine powder to as large as 40 mm in diameter. Although considered a by-product highly suitable as a road construction material, the high level of heavy metal leaching is an obstacle to its reuse. Weathering, a method used to reduce heavy metal leaching, is a lengthy process taking over thee months to complete. The chief reaction involved in weathering is carbonation occurring between Ca(OH)2 in bottom ash and CO₂(g) in the atmosphere. During this process, CaCO₃ is produced, causing the pH level to drop from over 12 to about 8.2 and reducing heavy metal leaching. In this paper, we attempt to determine the particle size best suited for reducing the period required for weathering bottom ash by identifying characteristics of different particle sizes that affect heavy metal leaching and neutralization.     

Polymer waste recycling over “used” catalysts

Catalytic degradation of high-density polyethylene (HDPE) was carried out under nitrogen using a laboratory fluidised bed reactor operating at 360 °C with catalyst to polymer feed ratio of 2:1 and at 450 °C with catalyst to polymer feed ratio of 6:1 under atmospheric pressure. The catalysts used in this study were ZSM-5, US-Y, ASA, fresh FCC (fluid catalytic cracking) commercial catalyst (Cat-A) and equilibrium FCC catalysts with different levels of metal poisoning were studied. The initial results for polymer degradation at 360 °C (catalyst to polymer ratio of 2:1) in a fluidised bed reactor in terms of the yield of volatile hydrocarbon products were: model catalysts>commercial FCC catalyst>E-Cats. However, when the process conditions more closely resembled to FCC conditions, the fresh commercial FCC catalyst was more favourable in terms of the yield of volatile hydrocarbon products. The degradation of HDPE over E-Cats although reduced was similar to ASA in product selectivity and yield, and the level of metal contamination did not affect the product stream generated. A simple economic evaluation of polymer recycling process is reported showing that a catalytic system based on E-Cats appears comparable in costs to a commercial thermal cracking plant.     

再生镁碳砖的性能、使用和质量控制

对再生镁碳砖和宝钢钢包渣线用新镁碳砖的性能指标、断面结构和使用效果进行了对比和分析,对提高再生镁碳砖质量和质量稳定性的措施进行了概括。结果表明:1)通过对拆炉、分拣、除杂、除渣、堆放和均化等每一环节的科学、细致、严格的管理,可以生产出优质的再生镁碳质原料;2)使用优质再生料,采用合理的生产工艺,可以生产出性能指标和使用效果达到甚至超过新镁碳砖的再生镁碳砖;3)再生镁碳砖使用效果好的原因是其致密度高,抗氧化性好,组织结构合理。     

Sludge Pre-Treatment through Ozone Application: Alternative Sludge Reuse Possibilities for Recirculating Aquaculture System Optimization

Recirculating Aquaculture Systems (RAS) reduce water consumption by efficient filtration to maintain appropriate levels of accumulating compounds and sludge. Sludge is mechanically separated by drum filters and disposed of to the detriment of overall system water budgets. Dissolved nitrogen compounds are reduced via nitrification–denitrification filters, requiring commercial external carbon sources. The reuse of sludge after ozone pre-treatment may represent the next step in RAS optimization. The present study analyzes the content of sludge from RAS and tests ozonation as a pre-treatment for recycling as carbon source. The dissociative effect of ozone and the physicochemical changes due to ozonation lead to a significant increase in soluble carbon availability. Predominantly long-chain fatty acid (FA) (saturated and unsaturated) with 16 and 18 carbon atoms independently of the treatment were found in the profiles. Saturated FA concentrations in solution increased after 20, 40, and 60 min ozonation. The solid content of the sludge was practically unaffected by ozonation in terms of FA profile: only saturated FA slightly increases after 40 min treatment. The implications of these findings for denitrifying bacteria are discussed.

Abbreviations: Recirculating Aquaculture Systems (RAS); Advanced Oxidation Processes (AOPs)     

Effect of ultrasound on thermoset polyurethane: NMR relaxation and diffusion measurements

Recycling of rubber-based materials is of increasing industrial environmental importance. In order to characterize the effect of ultrasound on polymer networks, nuclear magnetic resonance (NMR) relaxation and pulsed-gradient diffusion measurements were made at 70.5 °C in polyurethane rubber (PUR) and foam after subsequent treatment by intense ultrasound. The proton transverse relaxation decay was analyzed in terms of molecular and segmental mobilities of all motional species, a chemical and physical network as well as diffusing sol. The diffusivity spectrum, measurable in foams, reflected the changing molecular weight distribution of low-molecular weight sol and oligomers. It was observed that the effect of ultrasound was less pronounced in PUR than rubbers like SBR, PDMS and BR owing to its low degree of unsaturation. The investigation on the foams is the first of its kind to be reported.