An in situ ATR-FTIR study of mixed collectors BHA/DDA adsorption in ilmenite-titanaugite flotation system

This paper researched the enhanced flotation separation performance of ilmenite and titanaugite using the mixed collector benzhydroxamic acid/dodecylamine(BHA/DDA). The interface assembly mechanism was mainly investigated through in situ attenuated total reflectance Fourier transform infrared(ATRFTIR) spectroscopy combined with the two-dimensional correlation spectroscopy(2 D-COS) and X-ray photoelectron spectroscopy(XPS). It has been found that BHA/DDA mixed collectors successfully separate ilmenite from titanaugite at a molar ratio of 8:1. Zeta potential experiments suggested that, in the presence of mixed collector system, the BHA-DDA complex adsorbed on the ilmenite surface via the chemically adsorbed BHA and the electrostatically adsorbed DDA, however, the complex adsorbed on the surface of titanaugite unstably. According to in situ ATR-FTIR combined with 2 D-COS and XPS results,the interface assembly mechanism of BHA/DDA is summarized as: the function group of BHA molecules first binds to the metal sites on minerals to form bidentate ligand, then DDA co-adsorbed with BHA on the surface of minerals through hydrogen bonding. DDA may change the adsorption modes of some BHA on the ilmenite surface from four-membered ring to five-membered ring, while the modes on the titanaugite surface is true opposite. Finally, recommended adsorption configurations of the BHA/DDA complex on the two mineral surfaces are proposed.     

Effect of hydroxamic acid polymers on reverse flotation of bauxite

The effect of hydroxamic acid starch (HAS) and hydroxamic acid polyacrylamide (HPAM) on the flotation of diaspore and kaolinite was investigated by flotation test. It is found that HAS depresses diaspore but activates kaolinite in acidic pulp,while HPAM activates both diaspore and kaolinite in the pH range of 2.0 - 10.5. The measurement of zeta potential shows that both HAS and HPAM can increase zeta potential of negatively charged diaspore, which indicates the existence of chemical bonding or hydrogen bonding between the reagents and diaspore.By covering the collector dodecyl amine(DDA) on diaspore surface, HAS increases the hydrophilicity of minerals and depresses the flotation of diaspore,however HPAM activates the flotation of diaspore by increasing the adsorption of DDA on diaspore surface.     

Daughter minerals in fluid inclusions of garnet and diopside from Tongguanshan Copper Deposit by SEM／EDS and LRM

Tongguanshan copper deposit of Tongling large ore belt is one of the typical skarn copper deposits. Based on careful observation under microscope many daughter minerals including transparent ones and opaque ones have been distinguished in the fluid inclusions of garnet and diopside. The results of SEM/EDS (scanning electron microscope/energy dispersive spectrometer) and LRM (laser Raman microprobe) analysis show that these daughter minerals in garnet are sylvite, halite, sphalerite, chalcopyrite and carbonate. Sylvite daughter mineral is very popular in garnet and diopside. The existence of so much sylvite daughter mineral and other daughter minerals in the fluid inclusions indicates that the ore-forming fluid is of supper-high salinity and high potassium concentration. High potassium concentration in the fluid inclusions agrees with K-rich mesotype-acid rock and K-silicate alteration that occurred widely in this area. The daughter mineral assemblage in garnet and diopside is similar to the mineral assemblage of oreforming stage that followed skarn stage.     

Novel polyhydroxy cationic collector N-(2,3-propanediol)-N-dodecylamine: Synthesis and flotation performance to hematite and quartz

To enhance the performance of traditional cationic collector, a novel polyhydroxy amine collector N-(2,3-Propanediol)-N-dodecylamine(PDDA) was designed by introducing one propylene glycol group into dodecylamine(DDA). It was prepared by a nucleophilic substitution reaction, which showed better solubility and hydrophobicity than DDA and was firstly employed as the collector for the separation of hematite and quartz. Flotation tests showed that PDDA had an excellent flotation performance and signi...     

双相钢HC420/780DP动态力学性能及其本构模型研究

在应变率分别为0.001、0.100、1.000、10.000、100.000 s^－1和200.000 s^－1的条件下,测试了双相钢HC420/780DP的高速拉伸性能,研究了其在不同应变率下的动态力学行为,得到了不同应变率下的真应力?真应变曲线,分析了其屈服强度、抗拉强度、流变应力以及断裂延伸率随应变率的变化规律。结果表明,随着应变率的升高,双相钢HC420/780DP的屈服强度、抗拉强度和流变应力均有所升高,断裂延伸率呈现先升高后降低的趋势。另外,基于Johnson?Cook本构模型,建立并修正了双相钢HC420/780DP与动态应变率相关的塑性本构模型,并验证了修正后的模型。结果表明,通过修正得到的本构模型与试验曲线拟合效果较好。     

单宁酸在冷却水中的缓蚀性能研究

采用失重法对单宁酸在冷却水中的缓蚀性能进行了试验研究,考察了温度、不同材质挂片等影响因素,并对单宁酸与HEDP、ATMP进行了复配.结果表明,单宁酸有一定的缓蚀性能,且随着水温的升高缓蚀率有所下降;45℃,投加量为40mg/L时,对A3碳钢、H62黄铜、1Cr18Ni9Ti铝合金的缓蚀率分别为46.7%、41.3%、39.4%;单宁酸与HEDP、ATMP分别复配后的缓蚀性能明显增强.     

Rock creep modeling based on discontinuous deformation analysis

Creep is one of the major problems of deep underground mining that must be studied theoretically, experimentally, and numerically over a long period. Experiments and field tests are methods which can directly and more accurately describe the engineering practices as compared with others. However, these approaches are also time-consuming because creep problem of rock engineering, such as the roadway/tunnel squeezing phenomenon, usually lasts from several months to a few years. A numerical method can be employed to overcome this time-consuming problem. The discontinuous deformation analysis (DDA) method was originated in 1984 and received considerable attention from geo-engineers and researchers. The current paper discusses the creep calculation methods using the continuous and the discontinuous methods, and proposes a creep analysis method based on DDA. The method proposed in this paper can directly change the stiffness matrix while inheriting the advantages of the original DDA. Applying this method does not require any changes in the contact part of DDA. Thus, this method does not have any effect on the open–close iteration and convergence and can solve the creep problem, while maintaining the advantages of the original DDA. We theorized that creep problems are static problems, and based on this, the work using DDA in this study was divided into two parts: (1) addition of a new loop for the original DDA to “discredited” the total creep time into several time elements, thereby changing the material properties in each time element; and (2) division of each of the time elements by the time steps, similar to the original DDA. In this manner, one creep problem can be solved via assembling of static problems. Afterwards, the method mentioned above is employed to modeling a tunnel case. The evolution of the displacement filed and stress field during creep are analyzed and discussed.     

STUDY ON SOLUTION CHEMISTRY BETWEEN TANNIC ACID AND THE FLOTATION PULP OF WOLLASTONITE AND DIOPSIDE

The mechanisms of interaction betweentannic acid and calcium ions either addedexternally to or inherently present in the volution(dissociated from mineral surface),arestudied by the use of Inductively Coupled PlasmaAtomic Emission Spectroscopy(ICP-AES),Ultraviolet Spectroscopy(UV).It is found thatwollastonite has a high solubility in theconcentration of calcium ions,calcium ions areable to interact with tannic acid.     

多酚与玉米淀粉相互作用研究

多酚能够与淀粉发生相互作用,从而对淀粉特性产生影响。研究了7种常见食源多酚(原花青素单聚体、儿茶素、咖啡酸、单宁酸、没食子酸、绿原酸和阿魏酸)与高直链和蜡质玉米淀粉的相互作用。粒径分析结果表明,7种多酚主要与直链淀粉发生显著相互作用,能使高直链玉米淀粉的粒径增大,但对蜡质玉米淀粉粒径则有不同影响,其中,咖啡酸和绿原酸能减小它的平均粒径;淀粉-碘结合力分析结果表明,7种多酚均减小了两种淀粉溶液的淀粉-碘结合力,其中咖啡酸和阿魏酸对高直链玉米淀粉影响最为显著,咖啡酸和绿原酸对蜡质玉米淀粉影响较显著;红外分析结果表明,7种多酚能与两种玉米淀粉通过非共价键发生相互作用,其中阿魏酸、咖啡酸和绿原酸与直链淀粉作用最强;X-射线衍射结果表明,除原花青素和单宁酸外,其他多酚均能与高直链玉米淀粉形成V型复合物,但能与蜡质玉米淀粉形成V型复合物的只有阿魏酸。总体来说,多酚可通过非共价作用与淀粉分子结合,形成分子间或者分子内复合物。     

Flotation performance of a novel Gemini collector for kaolinite at low temperature

How to sustainably produce bauxite by effective reverse froth flotation of kaolinite at low temperature is an urgent problem to be solved in the field of mineral processing. In this work, a novel amino-based Gemini surfactant butadiyl-1, 4-bis (dimethyl dodecylammonium bromide) (BBDB) was prepared and first utilized as a novel collector for kaolinite flotation. Its flotation performance for kaolinite was compared with that of the common monomolecular surfactant 1-dodecylamine (DDA) by micro-flotation tests. The tests results indicated that 95% kaolinite recovery was obtained using 2.0 × 10⁻⁴ mol/L BBDB at 25 ℃, which was half of the dosage when DDA obtained the maximum kaolinite recovery of 81%. At extremely low temperature (0 ℃), 3.0 × 10⁻⁴ mol/L BBDB could still collect 91% kaolinite, while DDA showed a frustrating ability. The contact angle tests indicated that BBDB could still significantly improve the hydrophobicity of the kaolinite surface (contact angle 71.7°) than DDA (contact angle only 25.8°) at 0 ℃. The Krafft point comparison tests indicated that BBDB had a much lower Krafft point (below 0 ℃) than DDA. Fourier transform infrared spectroscopy (FTIR)-spectrum analysis and zeta potential measurements showed that BBDB was physically adsorbed on the surface of kaolinite through electrostatic interaction.     

Selective depression action of taurine in flotation separation of specularite and chloriteOA

Chlorite, as the most representative gangue mineral associated with specularite, of which the separation of these two minerals is difficult. This paper investigated the depression effect of taurine on specularite/chlorite separation via flotation experiments, adsorption tests, contact angle measurements, Zeta potential detection, FT-IR measurements, and XPS analyses. The results of single mineral flotation indicated that chlorite could be depressed selectively by taurine with the recovery of les...     

苯并噁嗪树脂插层蛭石纳米复合材料的制备与表征

分析了蛭石精矿和膨胀蛭石的组成和结构，用十六烷基三甲基溴化铵（CTAB）进行了有机化处理，再通过熔融或溶液混合插层苯并恶嗪树脂制备了苯并恶嗪树脂插层蛭石纳米复合材料，并采用蒙脱土进行了对照实验。结果表明：蛭石业矿是由蛭石、水金云母及金云母所组成。有机化处理使蛭石晶层的d001由1．46nm增加到2．67nm，并出现二级衍射峰d002=1.34nm。苯并恶嗪树脂插层后，蛭石层间距进一步增大，插层效果优于蒙脱土，而水金云母层间距没有变化；复合物固化后，有机化蛭石和水金云母的特征峰都消失了，表明形成了苯并恶嗪／蛭石纳米复合材料。     

沉淀法去除糖化酶中转苷酶的研究

研究了磷钨酸，十二烷磺酸钠，单宁酸三种试剂去除液体曲糖化酶中转苷酶的方法，利用正交试验了每种方法的最优工艺条件，在最优工艺条件下，磷钨酸法转苷去除率为７５．９％，糖化酶活力损失９．６％，十二烷基磺酸钠法转苷酶去除率为６９．１％，糖化酶活力基本不变；单宁酸法转苷酶去除率为７０．３％，糖化酶活力提高９．８％。     

Comparisons between centrifuge and numerical modeling results for slope toppling failure

This paper presents series studies on the toppling mechanism by centrifuge tests and numerical simulations. Two different discrete element methods, i.e., the continuum-based discrete element method(CDEM) and the discontinuous deformation analysis(DDA), are adopted. The modeling results show that both the methods can accurately capture the failure modes of the centrifuge tests, including three distinct zones and two failure surfaces. Comparisons are made between the physical test and numerical simulation results. The critical inclination angle of the tilting table where the slope models are fixed on can be moderately predicted by the two methods, with different degrees of precision. The error between the test results and the simulated results is within 1% for the slope models without rock-bridges by both CDEM and DDA. However, it is amplified for the staggered-joint models that simulate the rock-bridges. With DDA, the average error is about 5%, and the maximum error is up to 17%. While with CDEM, the errors for the aligned-joint models are ranged from 1% to 6%, and it is from 10% to 29% for the staggered-joint models. The two numerical methods show the capability in simulating toppling failure of blocky rock mass with and without rock-bridges. The model with rock-bridges which provides a certain bending resistance is more stable than the one without any rock-bridge. In addition, the two failure surfaces were observed, which is different from the common understanding that only one failure surface appears.     

DDA方法在波动问题计算中的初步研究

采用DDA方法验证了一维应力波在不同边界的响应情况;在此基础上,实现了位移和应力两种地震波输入方式,并对两种方法进行了比较。基于DDA的一维计算模型,研究了在计算波动问题时块体单元尺寸和节理刚度的取值问题。研究结果表明：DDA模型网格在波传播方向的尺寸取最短波长的1/15～1/20;随着法向刚度的降低,节理对弹性纵波的衰减作用增大;当节理标准强度大于0.5时,DDA计算的节理面透射系数与理论透射系数的误差在5%以内。此外,基于DDA方法中波动问题的初步研究成果,对某地下厂房在正弦波作用下的动力响应情况进行了简单地分析,分析成果与有限元计算结果基本一致,这为DDA方法用于工程实例的动力响应分析奠定了基础。     

由五倍子制取鞣花酸

以五倍子为原料浸取单宁酸 ,由单宁酸氧化制备鞣花酸。选用 Na2 CO3 作添加剂 ,降低单宁酸的浓度 ,增长反应时间 ,鞣花酸的产率可高达 54 %。采用红外光谱 ( IR)法和高效液相色谱法 ( HPLC)对制备的鞣花酸进行了分析     

二阶数据近似算法对DDA圆弧插补的改进

通过二阶数据近似算法对DDA圆弧插补优化改进分析，推导DDA圆弧插补及其改进算法的数学表示，证明了二阶数据近似算法对DDA圆弧插补的改进具有简单性和高速性，分析减少DDA圆弧插补径向误差与消除累积误差的有关参数，以进一步提高DDA圆弧插补精度。     

Stability classification model of mine-lane surrounding rock based on distance discriminant analysis method

Based on the principle of Mahalanobis distance discriminant analysis （DDA） theory, a stability classification model for mine-lane surrounding rock was established, including six indexes of discriminant factors that reflect the engineering quality of surrounding rock： lane depth below surface, span of lane, ratio of directly top layer thickness to coal thickness, uniaxial comprehensive strength of surrounding rock, development degree coefficient of surrounding rock joint and range of broken surrounding rock zone. A DDA model was obtained through training 15 practical measuring samples. The re-substitution method was introduced to verify the stability of DDA model and the ratio of mis-discrimination is zero. The DDA model was used to discriminate 3 new samples and the results are identical with actual rock kind. Compared with the artificial neural network method and support vector mechanic method, the results show that this model has high prediction accuracy and can be used in practical engineering.     

用吡嗪鎓氯铬酸盐进行的醇类氧化反应及其动力学研究

在6MHCl溶剂中,用吡嗪和三氧化铬合成出吡嗪翰氯铬酸盐(PyzCc),并用IR、EA、ICP 证实其结构。在酸催化的N．N-二甲基甲酰胺溶剂中,用PyzCc有效地氧化苄醇及其衍生物(P-CH3、 H、m-Br、m-NO2)。本实验中,吸电子基使反应速度减小,而供电子基使反应速度增加。Hammett反 应常数P值为-0．68(308K时)。由此可知,利用PyzCc的醇氧化反应经历先生成铬酸酯的过程后在定速 步骤发生质子转移的反应历程。     

Experimental and MD simulation of 3-dodecyloxypropanamine and 3-tetradecyloxypropylamine adsorbed onto quartz (1 0 1) surface

In this paper, two surfactants, 3-dodecyloxypropanamine (DOPA) and 3-tetradecyloxypropylamine (TOPA), were synthesized and used as collectors in the quartz micro-flotation in the laboratory. Micro-flotation tests, FT-IR, XPS measurements, and ab initio Molecular Dynamics (MD) simulations were conducted to research DOPA, TOPA, and dodecylamine (DDA)'s adsorption mechanisms onto quartz (1 0 1) surfaces. The results of micro-flotation show that the adsorption of DOPA and TOPA onto quartz surface is more robust than that of DDA. The zeta-potential result shows that the DOPA/TOPA was adsorbed on quartz through electrostatic attraction. Then, MD simulation adsorption models were built to compare the computational properties of the three surfactants, such as the radial distribution function, and the interaction energies between the collectors and the quartz cleavage surface. The interaction energies of surfactants (RNH₃⁺ or RNH₂) on the quartz surface explained why the pH range of DOPA/TOPA is wider than that of DDA. XPS analyses and MD simulations confirmed that DOPA bonded with the (1 0 1) surface of quartz through three types of hydrogen bonds between the NH₂ of DOPA and the O atom of quartz. The hydrogen bonds of type A and type C were the most likely type and more potent than those of type B.