硅矿物在拜耳法溶出中的行为

研究了高岭石、伊利石、叶蜡石等几种单体硅矿物在铝酸钠溶液中的溶出行为.结果表明,高岭石、伊利石、叶蜡石等单体硅矿物在铝酸钠溶液中的溶出速率受温度等反应条件的影响.采用量子化学理论计算,用CASTEP程序模块,在GGA-PW91基组水平,对高岭石、伊利石、叶蜡石及其常见完全解理面(001)slab模型进行几何优化,揭示了高岭石、伊利石、叶蜡石在铝酸钠溶液中反应活性差异的微观本质.高岭石、伊利石和叶蜡石的反应活性存在较明显的不同,其中叶蜡石的反应活性最大.伊利石的Si-O键结合力最强,Al-O键结合力相对最弱,相对最难反应脱Si;叶蜡石Si-O键结合力相对最弱,相对较容易反应脱除Si.OH-的存在对高岭石、伊利石、叶蜡石完全解理面的微观电子结构、Si-O键的结合力等均影响显著,其中OH-对高岭石表面性质及 Si-O键结合力的降低产生的影响最大,因此高岭石在相对较低温度下较易在碱性溶液中反应脱硅.     

脱硅产物对铝酸钠溶液水解性能影响的研究

随着氧化铝企业竞争的激烈和对节能降耗的要求,拜耳法生产过程中铝酸钠溶液的水解问题备受关注,其中处理三水铝石矿时水解程度更为严重。本文模拟三水铝石矿溶出条件研究了145℃下不同时间形成的脱硅产物及其含量对铝酸钠溶液稳定性的影响规律及其机理。结果表明,145℃脱硅条件下形成的水合铝硅酸钠由无定形沸石、方钠石和沸石组成,随着脱硅时间的延长,脱硅产物的结晶度逐渐增加,沸石的含量逐渐增加,方钠石的含量逐渐降低。提高脱硅产物的结晶度和沸石的含量有利于提高铝酸钠溶液的稳定性。随着脱硅反应时间的延长,铝酸钠溶液添加脱硅产物后的水解反应平衡常数逐渐降低。同时,脱硅产物的生成量越大,拜耳法过程铝酸钠溶液的水解程度越大。     

改变拜耳法预脱硅工艺降低赤泥化学结合碱的研究

研究了拜耳法预脱硅工艺,目的在于降低赤泥化学结合碱。在预脱硅段使用低碱、高ak溶液(沉铝液)对铝土矿进行脱硅,然后补进浓缩的循环母液溶出铝土矿,使铝土矿中的含硅矿物更多地转化为水化石榴石形态,达到降低赤泥化学结合碱的目的。实验研究发现,当预脱硅温度为160℃,反应时间为120min,沉铝液碱含量为15%,ak为30.8,配矿C/S比为1.3,溶出温度为260℃,反应时间为60min时,采用本方法溶出河南某地铝土矿产生的赤泥N/S从常规溶出赤泥N/S的0.42降为0.23。     

三水铝石矿中硅,铝矿物的溶解动力学

三水铝石矿在低压溶出时，活性硅矿物溶解进入溶液，随后发生脱硅反应，同时三水铝石溶解进入溶液。但是溶解的速率，不同的三水铝石矿有显著的差别，主要是铝土矿和矿物的微观结构不同。这种溶解速率的差别，对于某些矿石可在工程中应用，改变现有拜耳法或联合法的常规工艺。在拜耳法中改变了赤泥的化学、矿物成分，有望综合利用赤泥、降低拜耳法的碱耗；在联合法中拜耳法赤泥将不进入烧结法系统，而仅是处理脱硅生咸的硅渣。依据硅和铝矿物溶解速率不同而形成的新的处理方法，有显著的技术经济效果。     

论中国高硅低铁——水硬铝型铝土矿的几种处理方法

本文分析了中国目前氧化铝生产工艺的概况，指出我国氧化铝工业面临的困境。并且，论述了近些年来针对我国矿石特点提出的几种解决方法：选矿－拜耳法，焙烧强化溶出拜耳法，焙烧预脱硅－拜耳法，拜耳法两段溶出。     

论中国高硅低铁一水硬铝型铝土矿的几种处理方法

木文分析了中国目前氧化铝生产工艺的概况，指出我国氧化铝工业面临的困境。并且，论述了近些年来针对我国矿石特点提出的几种解决方法：选矿──拜耳法，焙烧强化溶出拜耳法，焙烧预脱硅──拜耳法，拜耳法两段溶出。     

中低品位铝土矿焙烧预脱硅的研究

研究了焙烧温度、浸出液固比和时间等因素对预脱硅的影响，并对出液和预脱硅业矿进行了苛化和拜耳法溶出性能试验。结果表明：经１０００℃焙烧的铝土矿，预脱硅后精矿的Ａ／Ｓ可由原矿的４．７３提高到１３．３，Ａｌ２Ｏ３回收率达９８％左右，铝精矿的拜耳法溶出性能与原矿相比略有降低。     

不同温度下Na_2O-Al_2O_3-CaO-SiO_2-CO_2-H_2O系中水化石(木畄)石(禾文)定区的确定

研究Na_2O-Al_2O_3-CaO-SiO_2-CO_2-H_2O系中水化石梢石的(禾文)定性,对进一步改进铝土矿和熟料的溶出、拜耳法赤泥洗涤、铝酸钠溶液的脱硅等过程,都具有重要的(乙心)义。     

一水硬铝石矿溶出新工艺的研究

在对一硬铝石矿硅钛矿物的反应行为及溶出动力学深入研究的基础上，对目前现有的拜耳法高温强化溶出工艺及装置的特点进行了剖析和比较，认为现有的拜耳法高温化溶出工艺对较难溶出且矿物组成十分复杂的一水硬铝石矿都存在某些不足，提出了一种更适合于含有复杂矿物的一水硬铝石溶出的新工艺，即“管道预热－脱硅脱钛－停留罐溶出”。该工艺综合了现有溶出的优点，对组成复杂的一水硬铝石矿具有良好的适用性，既保证了良好的溶出效果     

改变补碱途径对混联法氧化铝生产工艺和技术指标的影响

通过改变混联法氧化铝生产工艺流程的补碱途径,即由原流程的烧结法粗液加种分母液,经脱硅叶滤精制后部分进入种分槽给拜耳法补碱,改为部分烧结法粗液不加种分母液经脱硅后,进入拜耳法稀释槽,同拜耳法溶出浆液混合给拜耳法补碱。这样既解决了烧结法粗液经脱硅后的溶液不稳定问题,又降低了种分原液的苛性比值,使技术指标得到了很大的提高,经济效益尤为可观。     

直链烷基胺浮选铝硅矿物机理

研究了一水硬铝石和高岭石、叶蜡石及伊利石等几种含铝硅酸盐矿物在不同pH条件下的动电行为与浮选行为。一水硬铝石、高岭石、叶蜡石及伊利石的等电点（IEP）分别为pH6．2,4．3,2．0,3．4。在pH＞IEP时,烷基胺类阳离子捕收剂主要以静电作用吸附在一水硬铝石矿物表面,其浮选高岭石等3种铝硅酸盐矿物的可浮性大小顺序是叶蜡石＞高岭石＞伊利石。高岭石、叶蜡石和伊利石均是层状硅酸盐矿物,其破碎磨细时,将沿层间断裂,由于晶体结构的原因其层面荷负电荷。烷基胺类阳离子捕收剂以静电作用力吸附于铝硅酸盐矿物表面的层面使矿物疏水上浮。     

Removal of enrofloxacin from aqueous solutions using illite and synthetic zeolite X

Enrofloxacin uptake and removal from aqueous solutions using illite and synthetic zeolite X prepared from illite, were studied in batch experiments under varying pH, contact time, and initial enrofloxacin concentrations. The X-ray diffraction and Fourier transform infrared spectroscopy caracterization were used to analyse the enrofloxacin adsorption in order to elucidate the adsorption mechanisms. It was found that enrofloxacin could be efficiently removed at pH 7 and pH 8 for clay and zeolite X, respectively. In addition, the second order model of kinetics is more adopted for the two samples. The isotherms of adsorption of enrofloxacin by illite and zeolite X show that the latter has the twice higher adsorption capacity of the clay. Equilibrium data fit well with the Langmuir and Freundlich isotherms. Moreover, the cation exchange, the electrostatic interaction, the cation bridging and the formation of bidentate ligands were the possible mechanisms of the enrofloxacin retention.     

Surface properties and modeling potentiometric titration of aqueous illite suspensions

The potentiometric titration behavior of complex illitic clay minerals provided from different origins (two Tunisian illite samples and an American illite sample) was investigated and interpreted according to the surface complexation theory. In the present investigation, the focus is on the surface charge characteristics. The proton surface charge can be calculated by subtracting the supernatant titration curves from those of the illite suspension at ambient temperature with an aerated medium. The points of zero charge (PZC), which were determined using the Gran plot method and the fast titration technique, were in the range of ～8.5–9.2. Our potentiometric titration curves were modeled using derived parameters of the Gran method. The surface ionization constants were determined by implementing the theory of surface complexation models (SCMs): the NEM, the constant capacitance model (CCM), and the triple layer model (TLM). The pKas values determined from derived parameters of the Gran plot data were in the range of pKa₁ = 4.5–5.52 and pKa₂ = 9.78–10.4 and are compared to those obtained by SCMs.     

N-(3-氨丙基)-月桂酰胺对铝硅酸盐矿物的浮选

研究了N-(3-氨丙基)-月桂酰胺对高岭石、伊利石和叶蜡石的浮选性能。结果表明：N-(3-氨丙基)-月桂酰胺对这些铝硅酸盐都有较好的捕收性能，对高岭石、伊利石和叶蜡石的回收率分别在91％，90％和96％以上。矿浆pH值对3种矿物的可浮性影响较小，在一个较宽的pH范围内，3种矿浆的Zeta电位均为负值，矿粒表面荷负电。红外光谱证明，3种矿物中均含有-OH基。酸性介质中，捕收剂分子通过静电引力吸附在矿粒表面；碱性介质中，捕收剂分子通过氢键吸附在矿粒表面。矿粒的扫描电镜照片表明：叶蜡石颗粒主要呈薄片状；伊利石和高岭石颗粒晕不规则形状。     

Electrical conductivity of 1 : 1 and 2 : 1 clay minerals

The A.C. impedance plots were used as tools to analyze the electrical response of two varieties of Tunisian halloysite 1: 1 and illitic samples 2: 1 as a function of frequency at different temperatures (80–800°C). The real and imaginary parts of the complex impedance trace semicircles in the complex plane. Except for the illite, It-1, the second sample analyzed in this study, these plots give evidence for the presence of both bulk and grain boundary effect, above 600°C onwards. The bulk resistance of the materials decreases with the rise in temperature. Impedance Spectroscopy data reveal a non-Debye type of dielectric relaxation. The Nyquist plots show the negative temperature coefficient of resistance of both pure Tunisian illite and halloysite samples. The results of bulk electrical conductivity and its activation energy are presented for the two mineral clay samples. For illite It-1, the activation energy values estimated from the AC conductivity pattern and modulus pattern are very similar and suggest a possibility of a long-range mobility of charge carriers (ions) via hopping mechanism of electrical transport processes at higher temperature. On the other hand, for the halloysite sample provided from kasserine, (Ha-Kass), the modulus analysis admit that the electrical transport processes of the material are very likely of electronic nature. Relaxation frequencies follow an Arrhenius behavior with the activation energy values not comparable to those found for the electrical conductivity.     

Physicochemical and ceramic properties of clays from jebel kebar (Central Tunisia)

The mineralogical and chemical compositions and the physical properties are determined for three representative clay samples from the Sidi Bouzid area in Tunisia in order to evaluate their industrial aptitude for ceramic applications. The semi-quantitative mineralogical analysis shows that illite and kaolinite are the major clay phases associated with crystalline phases as quartz, K-feldspar and calcite. In addition, some quantities of smectite, interstratified illite–smectite, dolomite and gypsum are also detected. The chemical analysis reveals that the silica phase is relatively high. The CaO rate is approved by the mineralogical analysis. The classification of the selected clays by the Holtz and Kovacs diagram suggests their possible use in the manufacturing of the red bricks in ceramic industry. For the Geotechnical test, ceramic products were prepared by mixing the three clays with different weight proportions (40, 40, and 20% respectively for green clay, red clay and red silty clay samples).     

Comparative studies on flotation of illite, pyrophyllite and kaolinite with Gemini and conventional cationic surfactants

To search a novel class of effective silicate mineral collectors, the Gemini quaternary ammonium salt surfactant (butane-α, ω-bis(dimethyl dodeculammonium bromide), 12-4-12) and its corresponding conventional monomeric surfactant (dedecyl trimethyl ammonium bromide, DTAB) were adopted to comparatively study the flotation behaviors of illite, pyrophyllite and kaolinite. Three silicate minerals with the Gemini surfactant as collector reveal floatability far better than with the corresponding traditional one. At pH 6, the best recoveries of illite, pyrophyllite and kaolinite with 3.5×10-4 mol/L 12-4-12 are 99.2%, 91.7% and 99.6%, respectively. The fluorescence and contact angle measurement were also conducted for the further investigation of surfactants aggregation behavior and silicate mineral surface hydrophobic properties. FTIR spectra analysis and electrokinetic analysis show that the mechanism of adsorption of collector molecules on mineral surfaces is almost identical for the electronic attraction and hydrogen bonds effect. The superior collecting power of dimeric collector may be attributed primarily to its special structure and its essential properties.     

含钒石煤的悬浮焙烧过程：特性表征、热力学、动力学（英文）

系统地研究含钒石煤在悬浮焙烧过程中的热力学、动力学、物相转化和微观结构演变。热力学计算表明,在焙烧过程中,石煤中的碳在氧气充足的情况下燃烧并生成CO₂,石煤的主要质量损失区间为600～840℃,热分解反应速率在700℃左右达到峰值。通过Flynn-Wall-Ozawa(FWO)和Kissinger-Akahira-Sunose(KAS)方法验证,石煤的热分解反应由Ginstling-Brounshtein方程描述,表观活化能和指数前因子分别为136.09 k J/mol和12.40 s^-1。石煤中的伊利石在650℃时失去羟基,产生脱水伊利石,绢云母结构被逐渐破坏。随着温度的升高,石煤表面变得粗糙且不规则,焙烧温度为850℃时烧结严重。     

Flotation techniques for separation of diaspore from bauxite using Gemini collector and starch depressant

The floatability of diaspore and three kinds of silicate minerals,including kaolinite,illite and pyrophyllite,by a cationic Gemini surfactant as collector and starch as depressant was investigated as function of reagents concentration and pulp pH.Further studies of artificially mixed minerals and bauxite ore were also detailedly conducted.At last,the pre-desliming reverse flotation separation process was adopted.It can be concluded that the combinational use of a Gemini cationic collector and the starch dep...     

Preparation,qualities and defects of ceramic materials from Tunisian clay minerals

Mineralogy, chemistry, and plasticity of the raw clay materials from different Tunisian regions were studied. These clays, exploitable at eight quarries, are the only mineral resources for the ceramic industry in Tunisia. Powder X-ray diffraction revealed that illite and kaolinite are the major mineral phases. However, other clay minerals, such as illite/smectite mixed-layer, and chlorite are also present. The associated minerals detected in powdered materials are: quartz, calcite, feldspar and, dolomite. These raw materials are marly clays with 6–14% CaO, represented mostly by calcite; they show the greatest relative amount of Na₂O+ K₂O (~3.5%) and iron–oxide (~6%). The plasticity index and the liquid limit of the crude samples do not exceed 22 and 42%, respectively. This indicates that these clays belong to illitic clays, classified in the low to moderate plastic domains. The mineralogical, chemical, physical and technical results of the studied clays encourage the use of these materials for traditional ceramic. In addition, this paper shows that the ceramic defects observed in the pieces manufactured from these Tunisian clays are lamination, cracks, and lower mechanical and bending strength. Some solutions are offered to avoid these ceramic defects.