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Experimental and statistical assessments of the mechanical strength reliability of gamma alumina catalyst supports

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Particuology 2015年第4期13卷 74-81页

作者： Abdolreza Samimi Mozhgan Zakeri Basir Maleki Davod Mohebbi-Kalhori Department of Chemical Engineering University of Sistan and Baluchestan

The mechanical strength of solid catalysts is considered an important factor in terms of ensuring the reliable performance of industrial reactors. In this work, a pelletizing method was used to form gamma alumina support for catalysts. Response surface methodology （RSM） was employed to analyze and model the effects of various manufacturing parameters on the crushing strength of the supports. These parameters were binder concentration, compaction pressure, calcination temperature, and drying mode. The suggested model was verified by applying an analysis of variance to assess its validity with regard to crushing strength. The mechanical reliability of various supports was also determined by calculating their Weibull modulus values through linear regression of the Weibull equation. The material with the highest mechanical strength reliability will have both a high mean crushing strength and a high Weibull modulus, and the best values obtained for a support in this work were 70.7 MPa and 6.63, respectively. The conditions used to form this sample were： 20mass% binder concentration, 861 MPa compaction pressure, 466 ℃ calcination temperature, and gentle drying.

关键词： crushing strength Brittle material Weibull modulus Pelletizing Response surface methodology

New coating formulation for the slow release of urea using a mixture of gypsum and dolomitic limestone

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Particuology 2015年第6期13卷 62-67页

作者： Farahnaz Eghbali Babadi Robiah Yunus Suraya Abdul Rashid Mohamad Amran Mohd Salleh Salmiaton Ali Institute of Advanced Technology Universiti Putra Malaysia Selangor 43400 Malaysia Departments of Chemical and Environmental Engineering Faculty of Engineering Universiti Putra Malaysia Selangor 43400 Malaysia

The use of urea and urea-based fertilizers has increased considerably over the past 15 years. They cur- rently account for approximately 51% of the world＇s agricultural nitrogen consumption. However, about 20-70% of the applied urea fertilizer is lost to the environment, causing serious pollution and increasing costs. These losses come from leaching, decomposition, and ammonium volatilization in the soil during handling and storage. Controlled release by coating can be used to increase urea fertilizer efficiency. We studied the use of gypsum, sulfur, and ground magnesium lime as cost-effective coating materials. All these coating materials contain nutrients required by plants. The effects of the coating composition and proportion of sealant on the rate of urea release and the crushing strength of the coated urea were investigated. We found that coated urea with the same proportion of gypsum-ground magnesium lime （GML） exhibited low urea release and high crushing strength. The performance was enhanced when using polyols as a sealant on the surface of the coated urea. A surface morphology analysis indicated a uniform and smooth surface on the coated film. The efficiency of the coated urea improved by 34.2% when using gypsum-GML （ 1：1 ratio） containing 1.1% oolvols.

关键词： Ground magnesium lime crushing strength Rotary pan SealantPolyol

Comparative performance of different urea coating materials for slow release

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Particuology 2014年第6期12卷 165-172页

作者： Khairul Ridzwan Mohd Ibrahim Farahnaz Eghbali Babadi Robiah Yunus Department of Chemical and Environmental Engineering Faculty of EngineeringUniversiti Putra Malaysia Institute of Advanced Technology Universiti Putra Malaysia

Approximately 70%of the applied urea fertilizer may be lost into the *** loss is due to leaching,decomposition and ammonium volatilization in soil,water and *** coating,the slow release technology can be used to reduce losses and to increase the fertilizer *** has been used as a coating material,but the coating cracks easily because of its friability,sometimes being peeled off from the urea *** this study,four types of materials,namely,gypsum,cement,sulfur and zeolite,were mixed and used as coating materials to search for the most effective and cheap coating *** primary reasons for selecting these materials were improving fruit quality and preventing plant diseases,providing a plant nutrient,increasing soil fertility and water *** materials were also selected based on their availability,processiblity and *** effects of the coating materials,thickness,drying time,sieving and sealant on the crushing strength and dissolution rate of urea were *** urea with the same proportion of gypsum-sulfur exhibited high crushing strength and lower dissolution ***,the performance was further enhanced by applying molten paraffin wax on the hot urea *** images demonstrated that the micro-structure of gypsum-sulfur coated urea after sieving resulted in a smoother coated *** efficiency of the coated urea was improved by26%using gypsum-sulfur（20%total coating）,3%paraffin wax and sieving the coating materials before application.

关键词： Coating Urea Gypsum Sulfur Slow release crushing strength

Fabrication and Properties of Aluminabased Reticulated Porous Ceramics

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China's Refractories 2020年第2期29卷 31-36页

作者： LAO Dong JIA Wenbao WANG Yufan CHEN Ruoyu LI Shujing HEI Daqian WANG Zhonghua DING Yue ZHANG Wenhao LIU Meiqi Institute of Nuclear Analysis Technology Nanjing University of Aeronautics and AstronauticsNanjing 211106China College of Materials and Metallurgy Wuhan University of Science and TechnologyWuhan 430081China Wuxi Chenguang Refractories Co. Ltd.Yixing 214221China

The primary impregnation slurry was prepared using active alumina(56.25 mass%),kaolin(15 mass%),zirconia(3.75 mass%),deionized water(25 mass%),and extra adding FS(0.2 mass%)and CMC(0.4 mass%).The effects of the active alumina particle size(d50=5.043,2.934,and 1.629μm)on the rheology and the thixotropy of the slurry were *** was found that the bimodal activeα-Al2O3(AMA-10)with d50=1.629μm was *** secondary impregnation slurry was prepared using AMA-10,kaolin and zirconia as the main raw *** the alumina-based reticulated porous ceramics were fabricated by the organic foam impregnation method combined with a secondary vacuum impregnation *** influence of the AMA-10 content on the properties of the ceramics was *** residual stress of the specimens was analyzed by finite element *** results show that the smaller alumina particle size and multimodal distribution are beneficial to the thixotropy of the primary impregnation *** secondary vacuum impregnation technique can significantly improve the mechanical properties,the thermal shock resistance and the residual strength of the alumina-based reticulated porous *** the decrease of alumina content in the secondary impregnation slurry,the residual stress of the external layer of ceramic reinforcement gradually changes from tensile stress to compressive stress,which effectively inhibits the expansion of the surface crack,and remarkably improves the crushing strength retention ratio of alumina reticulated porous ceramics.

关键词： alumina reticulated porous ceramics organic foam impregnation method vacuum impregnation technique crushing strength residual stress thermal shock resistance

Effects of Al_(2)O_(3)-SiO_(2) Raw Material Types on Properties of Anorthite Based Insulation Refractories

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China's Refractories 2024年第1期33卷 23-27页

作者： DU Juan GUO Huishi YANG Jialin LI Wenfeng GUI Yanghai ZHAO Zhiqiang LIU Yingfan School of Materials Science and Engineering Henan University of TechnologyZhengzhou 450001China School of Materials and Chemical Engineering Zhengzhou University of Light IndustryZhengzhou 450051China

To optimize their Al_(2)O_(3)-SiO_(2) raw materials,anorthite based insulation refractories were prepared by the in-situ sintering process combined with the foaming method after sintering at 1350℃for 3 h,using green and pollution-free kaolin,kyanite,andalusite and sillimanite as Al_(2)O_(3)-SiO_(2) raw materials,respectively,and industrial CaCO_(3) as the CaO *** of Al_(2)O_(3)-SiO_(2) raw material types on the physical properties,phase composition and microstructure were *** results are as *** samples prepared by different Al_(2)O_(3)-SiO_(2) raw materials have hexagonal flake anorthite and a small amount of mullite and *** bulk density and thermal conductivity decrease in the order of using kaolin,andalusite,kyanite and sillimanite as the Al_(2)O_(3)-SiO_(2) raw material,but their apparent porosity ***,in the sample with kaolin,the bonding between anorthite crystals on the pore walls is closer than that of the other samples,which is conducive to increasing the cold crushing *** bonding between anorthite crystals on pore walls gradually decreases in the order of using kyanite,andalusite and sillimanite as the Al_(2)O_(3)-SiO_(2) raw material,thus their cold crushing strength decreases *** comprehensive consideration,the properties of the sample from kyanite are the *** apparent porosity,thermal conductivity and cold crushing strength are 84.6%,0.141 W·m^(-1)·K^(-1) and 1.89 MPa,respectively.

关键词： anorthite based insulation refractories Al_(2)O_(3)-SiO_(2)raw materials crushing strength thermal conductivity microstructure

The Effect of Bridging Liquid Surface Tension and Specific Surface Area on strength Factor of Coal Agglomerates

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Journal of Mechanics Engineering and Automation 2012年第2期2卷 91-95页

作者： Kingsley Okechukwu Ikebudu Emmanuel Chuka Chinwuko Emmanuel Okechukwu Chukwumuanya Dept. of Mechanical Engineering Faculty of Eng. ＆ EVM Anambra State University Uli Campus Anambra State 431124 Nigeria Department of Industrial/Production Engineering Faculty of Eng. Nnamdi Azikiwe University Awka Anambra State 420001 Nigeria

The aim of this research is to determine the effect of bridging liquid surface tension and specific surface area on strength factor of coal agglomerates. The production of coal agglomerates of the range 15-27.51 mm was achieved. The crushing strength of the agglomerates was determined for good handling of fine （coal-liquid mixture） to improve fugitive dust control, decrease in transportation losses, reduce risk of coal freezing, lower risk of spontaneous combustion, etc. in iron and steel industries, railway corporations and coal corporations. Kerosene （paraffin oil） was used as a binder and the agglomerated coal oil mixture was pelletized using balling technique （disc）. Mechanical and physical tests like compressive strength test, etc. were carried out. The relationship between the bridging liquid surface tension and specific surface area on strength factor of coal agglomerates showed that there is considerable variation in these parameters in the coal powder systems.

关键词： Sub-bituminous coal agglomerates breaking load crushing strength material handling.