变性淀粉在铝硅矿物浮选分离中的作用机理

通过浮选实验、动电位和红外光谱测定,详细考察了变性淀粉在铝硅矿物浮选分离中的作用效果和机理。浮选实验显示：非离子淀粉和阴离子淀粉在pH＜6时,抑制一水硬铝石的浮选,但当pH＞6时,却对一水硬铝石浮选有活化作用;阳离子淀粉在较宽pH值范围内对一水硬铝石均有抑制作用;3种淀粉化合物在pH＜6时均活化高岭石的浮选,当pH＞6时活化作用较微。结果表明：变性淀粉是一水硬铝石型铝土矿反浮选中实现一水硬铝石和高岭石分离的有效调整剂,阴离子淀粉使矿物表面ζ电位更负,阳离子淀粉使矿物质表面ζ电位更正,非离子淀粉使矿物表面电位绝对值减小。由实验结果结合药剂与矿物作用前后的红外光谱分析,得出结论：非离子淀粉主要通过氢键作用吸附于矿物表面,而静电力和化学键合力在阴离子淀粉和阳离子淀粉吸附中发挥着重要作用。     

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。     

阴离子-非离子组合药剂对一水硬铝石浮选和泡沫稳定性的影响

采用单矿物浮选实验,接触角实验,两相、三相泡沫动态稳定性实验,研究组合药剂油酸钠(NaOL)-辛醇(OCT)对一水硬铝石浮选行为的影响规律及其作用机理。通过测定组合药剂与一水硬铝石作用前后溶液的TOC含量,分析组合药剂作用下一水硬铝石三相泡沫稳定性的原因。结果表明:在矿浆p H=7.0条件下,组合药剂与单一NaOL浮选一水硬铝石结果相比,NaOL物质的量在组合药剂总物质的量中所占的摩尔分数x(NaOL)≥40%时有利于提高一水硬铝石的浮选回收率。其中,x(NaOL)=40%和x(NaOL)=60%的组合药剂因通过形成更稳定的三相泡沫而提高一水硬铝石的浮选回收率;x(NaOL)=80%的组合药剂不仅能增强浮选泡沫稳定性,还能增大矿物表面疏水性从而提高一水硬铝石浮选回收率。     

磷酸盐对一水硬铝石和高岭石浮选的选择性作用

研究了磷酸盐对一水硬铝石和高岭石的浮选性能。六偏磷酸钠(SHMP)在低用量条件下，对高岭石的抑制作用大于对一水硬铝石的，可以实现铝土矿的正浮选脱硅；而在高用量的条件下，六偏磷酸盐对一水硬铝石的抑制作用很强，对高岭石的抑制作用与低用量条件相比没有明显变化，因而可以实现铝土矿的反浮选脱硅。通过磷酸盐的溶液化学、六偏磷酸钠对一水硬铝石和高岭石矿物的ξ-电位影响及其在矿物表面上的吸附量测定，同时通过显微镜对溶液中的矿物颗粒成像，探讨了(NaPO3)6在一水硬铝石和高岭石的胺阳离子反浮选体系中的作用机理。     

胺类捕收剂的结构与性能研究

研究了脂肪伯胺、叔胺、多胺和醚胺四种药剂对高岭石、叶腊石、伊利石的浮选行为，结果表明捕收能力顺序为多胺＞叔胺＞醚胺＞脂肪＞伯胺。量化计算结果说明这两种胺类化合物易阳离子化，N数越多，N上烃基越多，药剂的阳离子化趋势越强。动电行为表明胺类化合物在铝硅酸盐矿物表面发生了静电吸附，当药剂极性基团电负性越大，改变矿物表面电性也越大。基团电负性、浮选剂特性指数、水油平衡度和疏水链长的计算表明捕收剂对铝硅酸盐类矿物捕收的决定因素是极性基的特性。     

有机硅阳离子捕收剂和淀粉抑制剂分选铝土矿（英文）

以有机硅阳离子表面活性剂TAS101为捕收剂,淀粉为抑制剂,研究一水硬铝石和3种硅酸盐矿物高岭石、叶腊石和伊利石的浮选行为。结果表明,在pH值范围为4-10时,TAS101对一水硬铝石和3种硅酸盐矿物均有较强的捕收能力。在碱性pH条件下,淀粉对一水硬铝石有较强的抑制效果但不会影响硅酸盐矿物的浮选。使用淀粉作为抑制剂,TAS101作为捕收剂能够实现一水硬铝石和3种硅酸盐脉石的浮选分离。对铝土矿浮选闭路试验进行进一步研究,采用反浮选流程,使用淀粉作为抑制剂,TAS101作为捕收剂,在pH=11条件下进行浮选,当原矿Al_2O_3与SiO_2的质量比为6.1时,可以获得Al_2O_3与SiO_2的质量比为9.58,Al_2O_3回收率为83.34%的精矿。     

铝土矿反浮选体系分散与凝聚理论

在铝土矿反浮选脱硅过程中,矿浆悬浮液的分散和凝聚状态对微细粒－水硬铝石的回收和精矿铝硅比有显著影响。要使各种硅酸盐矿物混合物达到有效的选择性分离,首先必需使矿浆悬浮液处于最佳分散状态,避免各种矿物细粒间的相互混杂和矿泥罩盖。针对高硅铝土矿反浮选脱硅过程,根据经典DLVO理论,从颗粒间的相互作用分析了微细粒－水硬铝石在各种含硅脉石矿物表面的粘附情况。结果表明：一水硬铝石与含硅脉石矿物颗粒间的范德化相互作用总是吸引;而它们间的静电相互作用在弱碱性条件下时为排斥,在弱酸性条件下时为吸引,一水硬铝石的夹带上浮较为严重,不利于铝土矿的反浮选。     

季铵型阳离子捕收剂在一水硬铝石和高岭石表面的吸附机理

研究十二烷基三甲基氯化铵（DTAC）和十六烷基三甲基氯化铵（CTAC）对一水硬铝石和高岭石的浮选行为。通过残余浓度法测定吸附等温线,荧光探针法和Zeta电位测试方法研究季铵型阳离子捕收剂在矿物表面的吸附机理。浮选结果表明：将DTAC和CTAC作为捕收剂,一水硬铝石的浮选回收率随着pH的增大而增加,而高岭石的浮选回收率随着pH的增大反而下降。当捕收剂的碳链增长时,矿物浮选回收率提高,但高岭石的增加幅度小于一水硬铝石的。在低浓度范围内,阳离子表面活性剂通过静电作用吸附在一水硬铝石表面,而对于高岭石,还存在离子交换作用。当浓度增大时,阳离子表面活性剂通过碳链间疏水缔合作用在两种矿物表面进一步吸附。矿物表面微极性研究表明：CTAC的疏水性比DTAC强,相同溶液浓度下CTAC在一水硬铝石表面能形成比在高岭石表面更大的胶团,这也说明阳离子表面活性剂碳链的增长对一水硬铝石吸附的影响要大,与浮选结果相吻合。     

油酸钠对一水硬铝石和高岭石的捕收机理

用油酸钠为捕收剂,研究了一水硬铝石和高岭石的可浮性,并对捕收剂与矿物的作用机理进行了探讨,结果表明：油酸钠对一水硬铝石和高岭石的捕收主要由两方面因素控制,在pH4-7范围内,为化学反应起主要作用,在pH7-10以形成离子-分子缔合物为主要因素,在以油酸钠为琢收剂时,矿物表面活性Al^3 数量的不同导致了高岭石和一水硬铝石的可浮性差异,这为铝土矿正浮选脱硅提供了理论依据。     

一水硬铝石型铝土矿铝硅浮选分离的溶液化学

分析了我国铝土矿中一水硬铝石和铝硅酸盐脉石矿物的晶体结构与表面性质,一水硬铝石与铝硅酸盐脉石矿物晶体结构的差异、表面断裂的Al-O和Si-O健及表面离子活性区的差别,可影响矿物表面的润滑性与可浮性,类质同象及各种晶格杂质离子也将影响浮选剂与矿物表面的相互作用和矿物可磨性,提出了正浮选、反浮吕硅分离的技术原型,用溶液化学与计算研究了其基本原理。结果表明,通过溶液化学计算可确定阴离子捕收剂正浮选脱硅时捕收剂,分散剂和PH三者之间的匹配关系,矿物的PZC与捕收剂的pKa值是阳离子捕收剂反浮选的主要控制参数,阴离子捕收剂反浮选时,铅盐和钙盐是浮选铝硅酸盐较理想的活化剂。     

Molecular structures and activity of organic depressants for marmatite, jamesonite and pyrite flotation

Ten kinds of organic depressants were used to investigate the depressing performance on marmatite and pyrite.Flotation results show that the organic compounds only with single group of hydroxyl(-OH),carboxyl(-COOH) or amino(-NH2) in molecule are ineffective in depressing marmatite,jamesonite and pyrite.The combinations of these functional groups still cannot enhance the depressing ability of organic depressant.The thioglycollic acid containing reductive functional group(-SH) has a good depressing performance for marmatite and pyrite.The presence of benzene ring in molecule can enhance the depressing performance.The functional group electronegativity,hydrophilic-hydrophobic indexes and frontier orbital of organic depressants were calculated,and the criterion for the depressing effect of organic depressants to sulphide minerals was proposed.     

羧甲基淀粉的取代度对其在反浮选中抑制一水硬铝石的影响(英文)

研究取代度不同的两种羧甲基淀粉(CMSL和CMSH分别表示取代度低和取代度高的羧甲基淀粉)在以十二胺(DDA)为捕收剂的阳离子反浮选中对一水硬铝石的抑制性能。考察了CMS的取代度对其抑制性能及作用方式的影响。单矿物浮选实验表明,在广泛pH值范围内,CMSL对一水硬铝石的抑制能力要好于CMSH。借助吸附量测试、动电位测量和原子力显微镜对CMS在一水硬铝石表面的吸附进行研究。结果表明:相对于CMSL,CMSH分子中具有更多的吸附点,因而在一水硬铝石表面具有较小的吸附量和较薄的吸附层厚度,并使一水硬铝石表面具有较强的电负性。溶液表面张力的测定和捕收剂DDA的吸附实验进一步揭示,CMSL分子的环式吸附构象可以罩盖更多的DDA从而显示优良的抑制性能,而CMSH/DDA体系则表现得更像一种表面活性剂。     

Pyrite oxidation in the presence of calcite and dolomite: Alkaline leaching,chemical modeling and surface characterization

The effect of calcite and dolomite on the oxidation of pyrite was studied using batch-leaching experiments complemented with chemical modeling, solution analysis and solid characterization techniques. Leaching tests conducted at 80 °C and p(O₂)=1.013×10⁵ Pa and pH>13 showed that pyrite alkaline oxidation rate decreased in the presence of both calcite and dolomite, while more detrimental effect was observed in the case of calcite. FE–SEM/EDS analysis exhibited a surface layer containing Ca (in the case of calcite) and Mg (in the case of dolomite) on the pyrite surface, which justified the slowdown in pyrite leaching rate. This surface layer was formed due to partial dissolution of carbonate minerals, which was affected dominantly by the pH and temperature of the leaching solution based on the chemical modeling data. The surface layer was characterized as Ca or Mg hydroxide using XRD and FTIR analysis. It was also found that this layer was thin and continuous in the case of calcite while it was thick and discontinuous in the presence of dolomite.     

Effect of hydroxamic acid starch on reverse flotation desilicate from diasporic bauxite

It is important to depress diaspore effectively in order to remove silicates from diasporic bauxite.A new water soluble polymer hydroxamic acid starch(HA-starch)was prepared.The effects of the product on the diaspore and kaolinite flotation were investigated and its reactive mechanism was studied by zeta potential measurement and FTIR.The results show that HA-starch can depress diaspore while make positive effect on kaolinite flotation at low pH value(pH below 6)The flotation recovery of diaspore was sharply decreased with the increase of concentration of HA-starch.The chemical adsorption of HA-starch on the surface of diaspore was revealed.     

A novel method to form hollow spheres of poly(3,4-ethylenedioxythiophene): Growth from a self-assemble membrane synthesized by aqueous chemical polymerization

Flexible self-assembled membrane and hollow spheres (1.7–4.6 μm in diameter) accompanied with self-assembled membrane of poly(3,4-ethylenedioxythiophene) doped with acetic acid were synthesized in aqueous solution using ammonium persulfate as oxidant. Scanning electronic microscope imagines approved the flexible membrane and sphere-like morphologies and indicated a “grow from membrane” process. The mechanism of self-assemble phenomenon was discussed by Fourier transform infrared and differential scanning calorimeter. It was found that self-assembly was driven by the hydrogen bond between 3,4-ethylenedioxythiophene monomers and acetic acid. The concentration of acetic acid plays an essential role in the self-assemble process. Moreover, the electrochemical properties of them with different morphologies were also characterized by cyclic voltammetry.     

Bi3.25La0.75Ti3O12纳米管的制备工艺研究

研究了一种Bi3.25La0.75Ti3O12 (BLT)铁电存储材料纳米管的简单有效合成方法。通过阳极氧化铝模板(AAO)辅助溶胶凝胶法,合成了BLT纳米管。其基本过程是以次硝酸铋、硝酸镧和钛酸四丁酯为原料,以冰醋酸和乙二醇甲醚为溶剂配制BLT溶胶,然后将BLT溶胶滴在AAO模板表面,浸润后烘干并反复多次,而后将材料在500 ℃下保温1 h,除去有机物,最后在750 ℃下保温30 min晶化,用KOH腐蚀去除氧化铝模板,即得到BLT纳米管。结果表明,BLT纳米管具有[117]择优取向;BLT纳米管管壁光滑,直径与模板孔径相当,约300 nm,且分布均匀,管壁厚度约25 nm,纳米管是多晶体,由粒径为8~12 nm晶粒组成     

A novel green depressant for flotation separation of scheelite from calcite

Polyaspartic acid (PASP) was used as a novel environmental-friendly depressant, and its inhibition effect on flotation performance of scheelite and calcite using sodium oleate (NaOL) as a collector was investigated by ways of flotation experiments, zeta potential measurement, contact angle measurement and infrared spectroscopic analysis (IR). The results show that PASP exhibits stronger inhibition capability and selectivity than acidified water glass, and the flotation separation of scheelite from calcite can be realized in the presence of 6 mg/L PASP and 20 mg/L NaOL at pH>6. In the presence of PASP, the zeta potential of calcite surface almost keeps unchanged after adding NaOL, and the contact angle decreases sharply. Therefore, it is indicated that PASP significantly decreases the adsorption of NaOL on calcite surface. By contrast, it has no distinct effect on the adsorption of NaOL on the scheelite surface, which is further confirmed by IR results.     

Adsorption of octanohydroxamic acid at fluorite surface in presence of calcite species

The surface properties of fluorite are often affected by dissolved gangue species (e.g., calcite) during the flotation process. Microflotation testing with and without the addition of calcite supernatant was conducted using octanohydroxamic acid (OHA) as the collector. The results revealed that dissolved calcite species significantly affected the flotation behavior of fluorite. Fourier transform infrared spectra confirmed that the decrease in flotation recovery was linked to lower OHA adsorption. Solution chemistry analysis indicated that CaCO₃ and Ca²⁺ from the calcite supernatant were the most favorably adsorbed species, and X-ray photoelectron spectroscopy analysis confirmed the surface adsorption of calcite species. Density functional theory simulations provided a detailed analysis of the multidentate adsorption configuration of OHA, which was the most favorable for adsorption on the fluorite surface. The adsorption energy calculation showed that the calcite dissolved species were more stably adsorbed on the fluorite surface than OHA. The pre-adsorption of calcite dissolved species hindered the adsorption of OHA due to electrostatic repulsion.     

Corrosion and corrosion control of mild steel in concentrated H2SO4 solutions by a newly synthesized glycine derivative

A newly synthesized glycine derivative (GlyD1), 2-(4-(dimethylamino)benzylamino)acetic acid hydrochloride, was used to control mild steel corrosion in 4.0 M H₂SO₄ solutions at different temperatures (278–338 K). Tafel extrapolation, linear polarization resistance (LPR) and impedance methods were used to test corrosion inhibitor efficiency. An independent method of chemical analysis, namely ICP-AES (inductively coupled plasma atomic emission spectrometry) was also used to test validity of corrosion rate measured by Tafel extrapolation method. Results obtained were compared with an available glycine derivative (GlyD2) and glycine (Gly). Tafel polarization measurements revealed that the three tested inhibitors function as mixed-type compounds. The inhibition efficiency increased with increase in inhibitor concentration and decreased with temperature, suggesting the occurrence of physical adsorption. The adsorptive behaviour of the three inhibitors followed Temkin-type isotherm and the standard free energy changes of adsorption () were evaluated for the three tested inhibitors as a function of temperature. The inhibition performance of GlyD1 was much better than those of GlyD2 and Gly itself. Results obtained from the different corrosion evaluation techniques were in good agreement.