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。     

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。     

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。     

氯化钠对铝硅矿物浮选的影响及其作用机理

采用季铵盐DTAL作捕收剂,研究了氯化钠对一水硬铝石和叶蜡石浮选的影响及其作用机理.随着氯化钠浓度的增加,叶蜡石的浮选回收率显著提高,而一水硬铝石的可浮性受其影响很小.机理研究表明:氯化钠对一水硬铝石的zeta-电位没有影响,而能显著降低叶蜡石的zeta-电位,增强捕收剂与叶腊石的静电作用,促进捕收剂的吸附而活化其浮选;叶蜡石表面电位的降低是因为氯离子对叶蜡石存在选择性吸附作用并对其结构进行插层,使得叶蜡石的层间距从0.93 nm增大至1.40 nm.溶液化学计算表明:氯化钠改变溶液的离子强度,显著降低了季铵盐阳离子表面活性剂的临界胶束浓度,使得吸附了捕收剂的矿物表面更容易疏水上浮.     

温度对油酸钠在一水硬铝石表面的吸附量的影响

通过吸附量的测定、热力学分析及单矿物浮选试验,揭示温度对油酸钠在一水硬铝石表面的吸附量及其浮选的影响。结果表明:在15℃时,油酸钠在一水硬铝石表面的吸附等温线为L-S型吸附曲线;在32℃时,其为L型吸附曲线。初始浓度在2 mmol/L以下时,油酸钠在一水硬铝石表面为单分子层吸附,吸附热约为-89.31k J/mol,属化学吸附,32℃时的吸附量高于15℃时的,ΘΔ15℃GΘ2Δ3℃G,温度的降低导致油酸钠的吸附量减少,主要是油酸钠的溶解度降低所致;低温下,增加矿浆温度比增大捕收剂用量能更有效地提高油酸钠吸附量及浮选回收率。     

新型螯合捕收剂COBA结构与捕收性能的关系

开发合成了一种新型廉价螯合捕收剂COBA,研究了它对一水硬铝石和高岭石的捕收活性、结构－性能关系及作用机理。结果表明：COBA对一水硬铝石的捕收能力强,而对高岭石的捕收能力弱,具有比水杨羟肟酸更好的选择性。其性能差异主要是由极性基结构差异即电负性、拓扑连接指数、断面尺寸和疏水性所引起的。COBA对一水硬铝石的捕收机理为： 其分子中的3个O原子通过化学成键与矿物表面Al原子形成了两环螯合物。     

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。     

金属离子对微细粒一水硬铝石分散性的影响(英文)

通过分散实验研究金属阳离子对一水硬铝石分散性的影响,以Zeta电位测试、溶液化学计算和DLVO理论计算分析金属离子对一水硬铝石分散性影响的作用机理。结果表明:金属离子的价态对一水硬铝石分散性的影响大于金属离子的种类,且多价金属离子对一水硬铝石分散性的影响比一价金属离子大。钙、镁离子存在时,当pH小于10,一水硬铝石的分散性不发生改变,但是当pH大于10后,钙、镁离子促使一水硬铝石发生强烈聚沉。钙、镁离子在一水硬铝石上的吸附使双电层厚度减小,从而降低Zeta电位绝对值并导致一水硬铝石颗粒间排斥力减小。当pH为11时,由于颗粒吸附Mg(OH)2(s),在一水硬铝石表面产生一个新的零电点。     

捕收剂预吸附对硫化矿与硅酸盐分离的影响

通过浮选试验、吸附量试验和红外光谱测试,考察捕收剂戊黄药(PAX)和抑制剂羧甲基纤维素(CMC)的添加顺序对绿泥石与黄铁矿浮选分离的影响,并研究其作用机理。结果表明:先加抑制剂羧甲基纤维素时,羧甲基纤维素是绿泥石的有效抑制剂,但也会抑制黄铁矿的浮选,影响绿泥石与黄铁矿的浮选分离;先加入捕收剂戊黄药时,羧甲基纤维素对黄铁矿的抑制作用减弱,而绿泥石的浮选回收不受影响,黄铁矿与绿泥石的分离选择性提高。抑制剂羧甲基纤维素能同时吸附在黄铁矿与绿泥石表面,而捕收剂戊黄药只能吸附在黄铁矿表面。戊黄药与羧甲基纤维素在黄铁矿表面存在竞争吸附,先加捕收剂时,戊黄药的预先吸附降低了羧甲基纤维素在黄铁矿表面的吸附量,减弱了羧甲基纤维素对黄铁矿的抑制作用,提高了黄铁矿与绿泥石的分离选择性。     

Tween80在一水硬铝石浮选中的作用

采用浮选试验、红外光谱和粒度分析研究Tween80对油酸钠浮选一水硬铝石的影响。结果表明:当Tween80与油酸钠以适宜的比例(质量比为1:9)混合时,有利于一水硬铝石的浮选;随着Tween80的增多,混合表面活性剂不利于一水硬铝石的浮选。加入Tween80强化了细粒级一水硬铝石的捕收,但没有明显改善油酸钠在低温下的捕收能力;油酸钠主要以阴离子形式吸附于一水硬铝石表面,且加入Tween80可能与油酸钠在一水硬铝石表面产生共吸附。     

Effect of modified starches on depression of diaspore

Four modified starches with selected charge characteristics including cationic starch (CAS), carboxymethyl starch (CMS), amphoteric starch (AMS) and soluble starch (SS) were investigated as depressants for diaspore in reverse flotation test using cationic collector (dodecylamine). Adsorption examination, Zeta potential measurement and Fourier transform infrared (FTIR) spectroscopy were used to clarify the role of the surface charge characteristics of starches in determining the adsorption behavior and depression performance as well as the mineral-starch interaction. Results show that the positively charged starches (CAS and AMS) display higher adsorption amounts and also better depression performance compared with the non-ionic (SS) and anionic starch (CMS), benefiting from the favorable electrostatic attraction with diaspore and also electrostatic repulsion with collector. FTIR spectroscopy proves the presence of hydrogen bonds and chemical complexation between mineral and starches in an integrated manner.     

苯二氧基二乙酸的相转移催化合成及其浮选性能

用三丁基乙基硫酸乙酯铵作相转移催化剂，以苯二酚、一氯乙酸和氢氧化钠为原料，用三氯甲烷作溶剂，合成了3种不同结构的苯二氧基二乙酸。分别以油酸钠、十二胺和丁黄药为浮选捕收剂，考察了苯二氧基二乙酸对方解石、一水硬铝石和黄铁矿的抑制性能。结果表明，苯二氧基二乙酸的抑制能力较强，对上述3种矿物的抑制性能大小顺序为：方解石＞一水硬铝石＞黄铁矿，可作为方解石等含钙、镁脉石矿物的有效抑制剂。从基团电负性、浮选剂特性指数和亲憎平衡值等方面，对苯二氧基二乙酸的抑制性能进行了讨论。用MINDO3方法对3种药剂进行了量化计算，量化计算结果表明，它们的抑制能力大小顺序为：对位＞间位＞邻位；它们均以负一价离子的形式与矿物中的金属离子发生作用，未离解的羧基则难以发生离解，从而保证药剂与矿物作用后的亲水性，使矿物得到抑制。     

Synergistic inhibition between dodecylamine and potassium iodide on the corrosion of cold rolled steel in 0.1 M phosphoric acid

The corrosion inhibition of cold rolled steel in 0.1 M aerated phosphoric acid (H₃PO₄) in the presence of dodecylamine (DDA) and potassium iodide (KI) has been investigated by Tafel polarization curve and electrochemical impedence spectroscopy (EIS) at 20 °C. The results obtained from polarization curve show that the inhibition efficiency of DDA with and without KI increases with increase in concentration of DDA but the inhibition efficiency of DDA without KI is not too high. A synergistic effect exists when DDA and KI are combined together to prevent cold rolled steel corrosion in 0.1 M H₃PO₄. All impedance spectra in EIS tests exhibit one capacitive loop which indicates that the corrosion reaction is controlled by charge transfer process. Inhibition efficiencies obtained from Tafel polarization, transfer resistance (R_t) are consistent.     

Inhibition mechanism of sodium laurate to underdeposit corrosion of carbon steels in NaCl solutions

Abstract

In a self-designed occluded corrosion cavity (OCC) simulated cell, the inhibition mechanism of sodium laurate (C₁₂H₂₃O₂Na) to the underdeposit corrosion of the N80 steel in a neutral 0·2 mol L^–1 NaCl solution was studied by electrochemical methods, including measurements of polarisation curves, coupling currents, polarisation resistances, electrochemical impedance spectra (EIS) and ion selectivity of the scale film. The results show that C₁₂H₂₃O₂^– could form a monomolecular adsorption film on the N80 steel surface in the studied solution, whose adsorption behaviour would follow Flory–Huggins isotherm model, and inhibit both anodic and cathodic processes. C₁₂H₂₃O₂^– displays good inhibition performance to the underdeposit corrosion of the N80 steel in the studied system, which could be mainly attributed to the inhibition to the electrode processes of the bulk cathode and occluded anode, the increase in the resistance of the corrosion deposit layer and the prevention to the autocatalysing acidification effect in OCC. The last two factors might be related to the conversion of the deposit layer from anion selectivity to cation selectivity and the formation of a hydrophobic layer on the wall of the micropores in the deposit layer by adsorption of C₁₂H₂₃O₂^–.     

Mechanism and application on sulphidizing flotation of copper oxide with combined collectors

The effect of sodium butyl xanthate (NaBX) and dodecylamine (DDA) as combined collector on the sulphidizing flotation of copper oxide was investigated by flotation test, fluorescent pyrene probe, zeta potential, and infrared spectroscopy analyses. The micro-flotation results show that combined use of NaBX+DDA yields better effect than using NaBX at pH 7-11 only, and the optimal molar ratio of NaBX to DDA is 2: 1. The actual ores flotation shows that when the dosage of NaBX+DDA is (100+54) g/t, the copper concentrate grade and recovery are 15.93% and 76.73%, respectively. The fluorescent pyrene probe test demonstrates that the NaBX+DDA can reduce the micelle concentration in the pulp. The zeta potential and the infrared spectroscopy analyses indicate that chemical adsorption, hydrogen-bonding and electrostatic interaction can help to adsorb NaBX+DDA on the surface of malachite. Meantime, copper xanthate and copper-amine complexes may be generated during the adsorption process.     

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.     

焙烧气氛对Pt/Al2O3 催化氧化CO和C3H6 性能的影响

使用Pt(NH₃)₂(NO₂)₂作为前驱体,通过过量浸渍法制备Pt/Al₂O₃催化剂,并将其在4种不同的气氛（H₂、O₂、NO或NH₃）中进行焙烧。利用N₂吸脱附、X射线衍射、程序升温还原（H₂-TPR）、CO脉冲吸附、CO原位漫反射傅里叶变换红外光谱（CO in situ DRIFTS）等手段对催化剂的物化性质进行了表征。结果表明：由于还原性焙烧气氛导致了众多小尺寸和高分散的Pt纳米颗粒的生成,经1%（体积分数）H₂/N₂焙烧的Pt/Al₂O₃表现出最佳的CO和C₃H₆催化氧化性能。     

Reverse flotation separation on diaspore and kaolinite in the presence of cationic polyacrylamide polymers

1　INTRODUCTIONChinaisrichindiasporebauxiteresources[1,2 ]whichpossessspecialpropertiessuchashighgradeofbothAl2 O3andSiO2 andlowFecontent,buttheAl/Si(massratioofAl2 O3toSiO2 )valueislow .Inordertotreatthediasporebauxite ,unitedmethodsandsin teringmethods[3] arestillappliedalthoughsufferingfromdisadvantagesincludingcomplextechnologyflowchart,highenergyconsumption ,highproduc tioncost ,andrestrainingfurtherdevelopmentofalu minaindustry .However ,byimprovingbauxiteAl/Si>10 ,wecanchoosem…