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Extended DLVO theory applied to coal slime-water suspensions

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Journal of Central South University 2012年第12期19卷 3558-3563页

作者：张明青刘颀刘炯天 School of Environment Science and Spatial Informatics China University of Mining&Technology School of Electric Power Engineering China University of Mining&Technology School of Chemical Engineering and Technology China University of Mining&Technology

Coal slimes are mainly composed of coal and clay *** interaction energies among these particles were calculated using extended DLVO(DERJAGUIN-LANDAU-VERWEY-OVERBEEK)theory and the aggregation mechanisms were analyzed based on the settling experiments for coal-kaolinite and coal-montmorillonite suspensions,respectively,under different conditions of water *** results indicate that for coal-kaolinite suspensions,as the water hardness reaches 10.0mol/L,the coal particles aggregate with each other easily,and then,the coal particles may aggregate with kaolinite ***,no aggregation occurs between kaolinite particles.A clay platelet network is formed in coal-montmorillonite suspensions by montmorillonite particles and coal particles are captured into the *** and montmorillonite particles settle completely.

关键词： coal slimes kaolinite montmorillonite extended DLVO theory aggregation mechanisms

Surfactant Enhanced Electrorenlediation of Phenanthrene

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Chinese Journal of Chemical Engineering 2003年第1期11卷 73-78页

作者：佘鹏刘铮丁富新杨建刚刘翔 Departmentof Chemical Engineering Tsinghua University Departmentof Environmental Science and Engineering Tsinghua University

Removal of hydrophobic organic contaminants (HOCs) from soil of low permeability by electroremedia-tion was investigated by using phenanthrene and kaolinite as a model system. Tween 80 was added into the purging solution in order to enhance the solubility of phenanthrene. The effects of pH on the adsorption of phenanthrene and Tween 80 on kaolinite and the magnitude of -potential of kaolinite were examined, respectively. The effects of electric field strength indicated by electric current on the electroremediation behavior, including the pH of purging solution, the conductivity, phenanthrene concentration and flow rate of effluent, were experimentally investigated, respectively. In case of an electric field of 25 mA applied for 72 hours, over 90% of phenanthrene was removed from 424 g (dry mass) of kaolinite at an energy consumption of 0.148 kW-h. The experimental results described in present study show that the addition of surfactant into purging solution greatly enhances the removal of HOCs by electroremediation.

关键词： electroremediation phenanthrene polycyclic aromatic hydrocarbon kaolinite electroosmosis

Using Kaolinitic Clay for Preparation of a Hydrotalcite-Like Compound

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Materials Sciences and Applications 2011年第6期2卷 684-691页

作者： Khaled Hosni Ezzeddine Srasra 不详

In this study, Mg-Al-CO3 hydrotalcite was synthesized from a kaolinite as natural source aluminium using two simple methods. The first method uses the kaolinite in natural solid state, the second method use the filtrate of the kaolinite after dissolution by acidic solutions. The structure of the materials was characterized by X-ray diffraction, Fourier transform infrared spectroscopy, differential scanning calorimetry (DSC) and Brunauer, Emmett, and Teller (BET) measurements.

关键词： Hydrotalcite kaolinite Layered Compound XRD Memory Effect

The Mineralogical and Engineering Characteristics of Cretaceous and Tertiary Shales in the Lower Benue Trough, Nigeria

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Journal of Earth Science and Engineering 2015年第8期5卷 487-498页

作者： Nnamdi Enyereibe Ekeocha Department of Geology University of Port Harcourt Choba PMB 5323 Rivers State Nigeria

The mineralogical and engineering characteristics of Cretaceous and Tertiary shales in the lower Benue Trough were determined with a view to establishing how they affect civil engineering construction, with emphasis on road pavements in the area. Shale samples from the geologic formations of Imo, Enugu and Awgu shales were subjected to the following laboratory tests： clay mineral content, organic matter content, Cation Exchange Capacity and Plasticity according to methods specified by the British Standard Institute. The shales were classified based on Plasticity Index, liquid limit and Cation Exchange Capacity. The class of shales ranged from non-plastic to extremely plastic and low to high reactivity. The moisture content and plasticity values are related to the degree of weathering. The higher the weathering grade, the higher the moisture content and plasticity values. The organic matter content of the shales is generally low （0.2% to 1 !.2%） and influences the durability of the shales in an inverse manner. The clay mineral composition from x-ray diffraction consists of lllite-montmorillonite mixed layers, illite, and kaolinite. The iUite-montmorillonite mixed layer clays are most prominent in road sections with most severe pavement failures. In contrast, sections with kaolinite as the dominant clay mineral experienced less severe and limited pavement failure. The contrasting engineering behaviour of these clay minerals is due to their structures. The study showed that the presence of clay minerals derived from underlying shales is a major contributory factor to the behaviour and performance of roads built over shale subgrades, that any effective remediation work must take cognizance of the amount and type of clay minerals present.

关键词： Cation exchange capacity illite kaolinite mineralogy montmorillonite plasticity.

PORCELAIN CRUCIBLE FUSION METHOD OF CERAMIC RAW MATERIALS HIGH IN ALUMINIUM AND ITS DETERMINATION

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Journal of Wuhan University of Technology(Materials Science) 1990年第2期5卷 39-48页

作者：熊得琼马小纪雷运春

This paper introduces the ceramic materials fusion method to use porcelain crucible instead of platinum crucible. By this method, not only the funds can be saved, but also the operation becomes simple and the analysed results are accurate and reliable. On the other hand, the high fusion point materials, such as high aluminum ceramic raw ma- terials, can also be melted and their aluminum contents can be determined by this method. Thus, it can be widely used in the students laboratory and routine analysis of small and middle industrial enterprises.

关键词： Fusion materials Porcelain crucible Platinum bauxite sample kaolinite Determine aluminium with silicon

Conditions for Thermal Activation of Ngwo Clay as an Alternative Resource for Alumina

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Natural Resources 2019年第1期10卷 1-15页

作者： Udochukwu Mark Charles Nwachukwu Anyakwo Okechukwu Onyebuchi Onyemaobi Chijioke Samson Nwobodo Department of Materials and Metallurgical Engineering Federal University of Technology Owerri Nigeria

The thermal activation of Ngwo clay from southeastern Nigeria for optimal leaching of alumina was investigated. The clay assayed 24.63% Al2O3 and 52.15% SiO2, comprising mainly kaolinite mineral and free silica or quartz. The alumina locked up in the clay structure was rendered acid-soluble by thermal activation which transformed the clay from its crystalline nature to an amorphous, porous phase or metakaolinite. The clay samples were heated at calcination temperatures of 500°C, 600°C, 700°C, 800°C, and 900°C at holding times of 30, 60, and 90 minutes. Uncalcined clay samples and samples calcined at 1000°C (holding for 60 minutes) were used in the control experiments. After leaching the resulting clay calcines in 1 M hydrochloric acid solution at room temperature, it was observed that the clay calcines produced at 700°C (holding for 60 minutes) responded most to leaching. Samples calcined for 60 minutes also responded better than those held for 30 or 90 minutes. Based on activation energy studies, it was observed that calcines produced at 700°C (for 60 minutes) had both the highest leaching response (51.84%?after 1 hour at leaching temperature of 100°C) and the lowest activation energy of 25.03 kJ/mol. It is concluded therefore that Ngwo kaolinite clay should?be best calcined for alumina dissolution by heating up to 700°C and holding for 60 minutes at that temperature. The clay deposit has potential for use as alternative resource for alumina production in Nigeria where bauxite is scarce.

关键词： Ngwo Clay Bauxite kaolinite Alumina Calcination Thermal Activation Leaching

Characterization and Iron Removal Treatment of Ion-Adsorption Rare Earth Tailings in Southern China

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Journal of Minerals and Materials Characterization and Engineering 2016年第2期4卷 127-134页

作者： Yongqing Wang Xin Nie Qibing Chang Huayin Liang Xiaozhen Zhang Jian-Er Zhou School of Materials Science and Engineering Jingdezhen Ceramic Institute Jingdezhen China

The ion-adsorption rare earth tailings have become a serious environmental pollution in Southern China, yet the potential of their economical value has not been fully exploited. In this work, the chemical and mineral compositions of the ion-adsorption rare earth tailings were characterized by Mineral Liberation Analyze (MLA) and XRF. The results show that 91.98 wt% of the tailings are composed of kaolinite and quartz, latter of which was removed by the sieving method. The other minor minerals contain feldspar, biotite, muscovite, titanomagnetite and limonite. Amongst these, the iron-bearing minerals are mostly found in the titanomagnetite and limonite which can be mostly removed by using a periodic high-gradient magnetic separator with a magnetic induction of 0.6 Tesla. The Fe2O3 content of the tailings changed from 2.11 wt% to 1.06 wt% after the sorting process, which met the Chinese national standard of TC-3 grade raw materials for ceramic industry applications. The Fe2O3 content in kaolinite was further decreased after Na2S2O4 treatment.

关键词： Tailings Resource Rare Earth Iron Removal kaolinite Magnetic Separation

Determination of the Calcination Procedure Required to Activate Edda Clay for Optimal Leaching of Alumina

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Journal of Minerals and Materials Characterization and Engineering 2019年第2期7卷 49-63页

Nigeria is the highest consumer of aluminium in Africa but lacks bauxite deposits. The replacement of bauxite alumina with other alumina bearing resources (clays in particular) has been proposed. The present study investigated the thermal treatment required to activate Edda clay from southeastern Nigeria for optimal leaching of alumina. The clay is composed mainly of kaolinite and quartz, assaying 24.65% Al2O3 and 52.81% SiO2. Thermal activation of the clay prior to leaching transformed the crystalline kaolinite mineral to an amorphous phase (metakaolinite) in which the alumina became soluble. Clay samples passing 300 μm sieve were calcined at temperatures of 500°C, 600°C, 700°C, 800°C, and 900°C at holding times of 30, 60, and 90 minutes in each case. The uncalcined clay and sample heated at 1000°C (for 60 minutes) were used in the control experiments. Leaching of alumina from the resulting clay calcines was done in 1 M hydrochloric acid solution at room temperature using a solid/liquid ratio of 0.02 g/ml and shaking speed of 100 rpm. The solubility data based on the percentage of Al ions taken into leach solution showed that the sample calcined at 700°C (for 60 minutes) responded to leaching better than other samples. Samples calcined for 60 minutes at all temperatures studied were found to respond more than those held for 30 or 90 minutes. Studies on the activation energy of leaching revealed that calcines produced at 700°C (for 60 minutes) had both the highest leaching response (49.96% after 1 hour at leaching temperature of 100°C) and the lowest activation energy of 24.47 kJ/mol. It is concluded therefore that Edda kaolinite clay should be thermally activated for alumina yield by heating up to 700°C and holding for 60 minutes. The clay deposit is therefore a potential alternative resource for alumina production.

关键词： Edda Clay Bauxite kaolinite Alumina Calcination Thermal Activation Leaching

Synthesis of Electroconducting Hydroxy-Sodalite/Graphite Composite: Preparation and Characterization

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Advances in Materials Physics and Chemistry 2019年第3期9卷 25-36页

作者： Rima Alomari Muayed Esaifan Mohammed Khair Hourani Hiba Al Amayreh Mohammed Amayreh Hani Khoury Department of Chemistry The University of Jordan Amman Jordan Department of Chemistry Faculty of Arts and Sciences University of Petra Amman Jordan Department of Physics and Basic Science Faculty of Engineering Technology Al-Balqa Applied University Amman Jordan Department of Geology The University of Jordan Amman Jordan

Electroconductive hydroxy-sodalite/graphite composites were synthesized by alkali-activation of kaolinite in the presence of sodium hydroxide as the alkali activator and graphite as a conductive filler. Thermal, morphological and microstructural properties in addition to direct current (D.C.) conductivity of the prepared composites were investigated. Thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy in the attenuated total reflection mode (FTIR/ATR), X-ray diffraction (XRD), scanning electron microscope/energy dispersive using X-ray analysis (SEM/EDX) and DC conductivity measurements were used to characterize the prepared composites. The effect of the hydroxyl-sodalite-to-graphite and NaOH-to-kaolinite ratios on the electrical conductivity was investigated and evaluated on the generated composite specimens made of Jordanian kaolinite or pure kaolinite. It was demonstrated that increasing the mass ratio of graphite-to-kaolinite in the clay-based composites increased the electrical conductivity of the resultant composites. It was also observed that using 1:1 graphite-to-pure kaolinite mass ratio showed the best electrical conductivity value of 3 × 10-3 s/cm, among the other mass ratios used for pure kaolinite specimens, while using 1:1 mass ratio of graphite-to-Jordanian kaolinite showed a conductivity of 1.6 s/cm.

关键词： kaolinite Graphite Composite Inorganic Polymers Electroconductive Composites