氯化钠存在下应用氯化亚锡-罗丹明B-水体系浮选分离钯

研究了氯化钠存在下氯化亚锡-罗丹明B-水体系浮选分离钯的方法及条件，在盐酸介质中，钯（Ⅱ）浮选率为100%，并与常见贱金属分离，对方法在分光光度法中的应用进行了研究，并对浮选模型进行了探讨。     

Ion flotation of cations of cerium group

The results of experimental investigation of ion flotation in solution of cerium, samarium, and europium nitrates as well as of sodium dodecyl sulfate, which was used as flotation reagent, were reported. The dependences of the distribution coefficients of rare earth ions in the ion flotation on pH of an equilibrium aqueous phase were obtained. Comparison of an extraction pH with a pH of hydrate formation allows making a conclusion on the flotation form of cerium, samarium, and europium cations.     

泡沫浮选法分离富集三七中的4种人参皂苷

采用泡沫浮选法对三七提取液中的人参皂苷Rg1、Re、Rb1和Rd进行了分离富集,并用高效液相色谱法分别测定了含量.考察了浮选液浓度、浮选时间、浮选液pH值、氮气流速和电解质NaCl浓度对浮选效率的影响.结果表明:泡沫浮选法对4种皂苷均有较好的分离富集效果,尤其是对人参二醇型皂苷(Rb1,Rd)效果更为明显.当浮选液浓度为2.0 mg/mL,pH值为2～3,氮气流速为20 mL/min,浮选时间10 min,电解质氯化钠浓度0.20 mol/L,泡沫浮选效果最佳.     

Zinc Recovery from Wulagen Sulfide Flotation Plant Tail by Applying Ether Amine Organic Collectors

Separating oxidized zinc minerals from flotation tailings is always a challenge. In this study, a flotation tailing from Wulagen zinc mine in China (Zn grade < 1%) was processed using froth flotation with combinations of amines (OPA 10, OPA 1214, OPA 13, DDA) and Na₂S to study the effects of these amines on the zinc recovery as well as their interactions with other reagents, aiming to screen out a proper reagent scheme to improve zinc separation from extremely low-grade zinc flotation tailings. The results show that different amines led to different flotation performance, and the collectors were ranked as OPA 1214, OPA 13, OPA 10 and DDA in a decreasing order based on flotation collectivity and selectivity. An increase in the concentration of each collector increased the zinc recovery but reduced the concentrate zinc grade. Interactions were also observed between different amines and Na₂S and Na₂SiO₃, and OPA 1214 outdid the others in saving the usage of both the Na₂S and Na₂SiO₃. The measured adsorption of collector onto smithsonite was found to correlate well with flotation test results. It was concluded that hydrocarbon chains can be held accountable for the difference in the flotation performance with different amines. The longer the hydrocarbon chain, the stronger the hydrophobic association ability of amine, which is conducive to the selective amine adsorption onto sulfurized smithsonite particles and hence the smithsonite flotation.     

Types of particles recovery—water recovery entrainment plots useful in flotation research

This review paper deals with graphical representation of entrainment experienced by fine particles during passing, either barren or mineralized, bubbles through flotation cells. Entrainment, also called mechanical carryover or mechanical flotation, is harmful because it reduces the quality of flotation concentrates. It was presented in the paper that it is convenient to show the results of entrainment as upgrading separation plots relating recovery of fines vs. water recovery. The shape of the entrainment separation curves significantly depends on the way flotation test is performed, type of flotation machine, kinetics of process, froth collecting time, concentration of frothers, collectors and modifiers, amount of air in flotation, density of pulp, amount of supplied water etc. Five types of entrainment separation plots were distinguished and presented in the paper. They were categorized as linear (type 1), linear shifted down (type 2), reaching plateau (type 3), increasing (type 4) and linear shifted up (type 5). The plots are useful for determination of appropriate entrainment coefficients characterizing the process.     

基于LSTM的浮选钼精矿品位软测量模型

战略性稀有金属钼矿品位低,组分复杂、嵌布粒度细等特点,其有价金属分离回收难。浮选作为微细粒钼矿分离回收的主要选矿方法之一,其浮选钼精矿品位一直是选厂的关键性产品指标。国内大多数选厂采取轮班制采样,人工化验得到精矿品位结果,但此方式严重滞后于浮选工艺,难以满足对生产过程进行实时监测和操作指导。LSTM是一种特殊的循环神经网络,引入门机制有效的传递或选择性遗忘长时间序列中的信息,解决RNN中的长期依赖、梯度消失和爆炸问题。本文分析整理东坡选厂中各平台源数据,结合选厂浮选工艺及机理,筛选出多个影响浮选钼精矿品位的变量作为模型输入;将输入变量进行异常值判定,缺失值填充和数据降噪等数据预处理,建立高质量浮选钼精矿品位数据库;软测量模型采用PyCharm软件编码,使用BatchNorm批量规范化处理样本数据,加入Dropout正则化防止过拟合,建立基于LSTM的浮选钼精矿品位软测量模型,通过前向传播算法更新神经网络结构参数,并于Linear模型和CNN模型的预测性能指标结果比较。结果表明：基于LSTM的浮选钼精矿品位软测量模型预测准确度高,样本数据误差波动平稳,浮动范围小,模型泛化能力强,模型平均绝对百分比误差MAPE为1.13%,均方根误差RMSE为0.7049%,决定系数R2为0.8763,实现了浮选钼精矿品位的在线预测。     

Surface activity and mercury flotation in solutions of n-dodecanoic acid and n-dodecylamine

The flotation and adsorption properties of two ionic collectors (n-dodecylamine andn-dodecanoic acid) are compared on the bases of results of mercury flotation in the model flotation apparatus and electrochemical measurements of the double layer capacity.The flotation recovery and the adsorption parameters (standard free enthalpyG° _A, the interaction coefficient of Frumkin's isotherm, the surface area per molecule) have been determined within the pH range 2.5–12 in solutions of various collector concentrations containing 0.1 N KCl. The maxima of flotation recovery and surface excess have been found at pHs corresponding to pK values for both substances. The influence of the electrolyte on flotation recovery and the gas bubble size distribution dependent upon the pH of the solution is presented forn-dodecanoic acid. The maxima of flotation recovery are involved through the formation of ion-molecule associates (11) as well as an optimum of the bubble size distribution.Publ.-No. 811 from Research Institute of Mineral Processing, Academy of Sciences of the German Democratic-Republic, Freiberg.     

溶剂浮选法分离富集大黄中的有效成分

采用溶剂浮选法对大黄提取液中的芦荟大黄素、大黄素、大黄酚以及大黄素甲醚进行了分离富集,并用高效液相色谱法分别测定了其含量。考察了料液浓度、浮选溶剂、浮选时间、浮选液pH值、氮气流速和电解质NaCl浓度对浮选效率的影响,并与泡沫浮选法和溶剂萃取法进行了比较。结果表明：溶剂萃取效果最差,泡沫浮选次之,溶剂浮选法分离富集效果最好。当料液浓度为6．4mg／mL,浮选时间为30min,浮选液pH一1～2,氮气流速为20mL／min,电解质NaCl浓度为0．4mol／L时,溶剂浮选效率最佳。     

Beneficiation of borax by reverse flotation in boron saturated brine

Flotation is one of the plausible methods for recovering borax fines discharged as fine waste to the tailings dam in the Kirka borax processing plant. A literature review dealing with the flotation behavior of boron minerals reveals that clay minerals in the boron ores coat boron minerals and thus deteriorate the quality of boron concentrates produced by direct flotation. The main objective of this study is therefore to recover borax fines from the tailings of the concentrator by reverse flotation. A three-level-factor experimental design was used to determine the main and interaction effects of variables selected on the metallurgical performance of reverse flotation. An analysis of variance for experimental results indicates that interaction effects of the variables for concentrate quality and recovery of B2O3 is nonsignificant and the most important variable for grade of concentrate and recovery is the collector dosage. It is shown that a concentrate assaying 11.25% B2O3 with 89.90% B2O3 recovery could be produced by means of single-stage (rougher) reverse flotation. Additionally, in order to produce a sufficient-quality concentrate, a multistage reverse flotation scheme involving rougher, scavenger, and two cleaners was devised. A final concentrate containing 23.47% B2O3 with 81.78% B2O3 recovery was obtained from these tests. The reverse flotation method can be thus considered as an important option for the beneficiation of borax fines.     

Preconcentration and separation of cadmium by use of cobalt(III) hexamethylenedithiocarbamate as a collector prior to its determination by atomic absorption spectrometry

Co(III) hexamethylenedithiocarbamate has been applied as a collector in colloid flotation preconcentration of Cd from water prior to electrothermal atomic absorption spectrometry (ETAAS). All experimental parameters necessary for successful flotation have been studied and optimized. The ETAAS results were compared with those obtained by inductive coupled plasma-atomic emission spectrometry (ICP-AES). The ETAAS detection limit was found to be 0.003 microg L(-1) Cd.     

Yeast flotation viewed as the result of the interplay of supernatant composition and cell-wall hydrophobicity

Flotation is a process of cell separation based on the affinity of cells to air bubbles. In the present work, flotability and hydrophobicity were determined using cells from different yeasts (Hansenulla polymorpha, Saccharomyces cerevisiae, Candida albicans), which were propagated in different media and at different temperatures. Alterations to the supernatant of the cells were also carried out before the flotation assays. The results described here indicate that supernatants of the yeast cells can play a more important role on flotation than cell-wall hydrophobicity. For example, wall-hydrophobicity of strain FLT-01 of S. cerevisiae was high but flotation did not occur when their washed cells were resuspended in water. Additions of neopeptone to cultures of S. cerevisiae and H. polymorpha repressed flotation and increased the volume of foam. An additional task of the present work was to show that the relationship between cell-wall hydrophobicity and flotation performance was dependent on the method used for the measurement of hydrophobicity. Based on the assay procedure, two types of hydrophobicity were distinguished: (a) the apparent hydrophobicity for cells suspended in the medium and expressed by the degree of cell affinity to the organic solvent in the two-phase system supernatant/hexane; (b) the standard hydrophobicity, which was determined for cells suspended in a standard solution (acetate buffer, in the present work) within the acetate buffer/hexane system. Flotation of cells of S. cerevisiae and C. albicans were best related to the degree of apparent hydrophobicity (varying with the supernatant composition at the cell/medium interface) rather than to the degree of standard hydrophobicity (varying with the alterations in the wall components, since the liquid phase was constant in the assay). However, depending on the yeast unpredictable results can be obtained. For example, cells of H. polymorpha exhibited good flotation associated to a high degree of standard hydrophobicity while having a lower degree of apparent hydrophobicity. Concerning growth temperature, flotation of cells of C. albicans was strongly repressed when the temperature was raised from 30 to 38 °C while a similar effect was not observed in cultures of S. cerevisiae and H. polymorpha. It is difficult to understand and predict flotation of yeast cells but simple modifications made to the supernatant of cultures can activate or repress flotation.     

An HPLC Method for the Determination of Amines in Flotation Pulp Based on Derivatization

Alkyl amines are surfactants used as quartz collectors in the reverse flotation of phosphate ores. It is important in both research and industrial practice to quantify amine concentration in the solution and/or wastewater. A simple and rapid method using high-performance liquid chromatography (HPLC) was developed to quantitatively determine the concentration of amine collectors (including dodecylamine, tetradecylamine, hexadecylamine, and octadecylamine) in a mineral flotation system. The method involved a sample derivatization procedure with 9-fluorenyl methoxycarbonyl chloride (FMOC-Cl) and separation/determination by HPLC coupled with a fluorescence detector. The calibration curves showed good linearity (R²?>?0.9956) in the range of 0.20–5.00 µg/mL, and the recoveries of dodecylamine, tetradecylamine, hexadecylamine, and octadecylamine were in the ranges of 84.93–97.64%, 89.93–101.92%, 85.29–98.37%, and 93.57–103.26%, respectively. The method was successfully used to quantify amines in wastewater from flotation experiments and artificial flotation wastewater (amine solution after activated carbon adsorption). The results from the analysis of four amines in the solution demonstrated that the proposed method is suitable for the simultaneous determination of amines in flotation pulp and wastewater.

     

硫酸铵-碘化钾-氯化十六烷基吡啶-水体系浮选分离镉的研究

研究了硫酸铵-碘化钾-氯化十六烷基吡啶-水体系浮选分离镉的行为及其与常见离子分离的条件。结果表明，控制pH5．0，在1．0g(NH4)2SO4存在下，Cd^2 可被碘化钾-氯化十六烷基吡啶-水体系浮选，而Zn^2 、Mn^2 、Fe^2 、Co^2 、Ni^2 、A1^3 等离子在该体系中不被浮选，可实现Cd^2 与这些离子的定量分离。对合成水样进行了浮选分离测定，结果满意。     

Preconcentration and separation of cadmium by use of cobalt(III) hexamethylenedithiocarbamate as a collector prior to its determination by atomic absorption spectrometry

Co(III) hexamethylenedithiocarbamate has been applied as a collector in colloid flotation preconcentration of Cd from water prior to electrothermal atomic absorption spectrometry (ETAAS). All experimental parameters necessary for successful flotation have been studied and optimized. The ETAAS results were compared with those obtained by inductive coupled plasma-atomic emission spectrometry (ICP–AES). The ETAAS detection limit was found to be 0.003 μg L^–1 Cd.     

Studies on the liquid-liquid extraction and ion and precipitate flotation of Co(II) with decanoic acid

The liquid-liquid extraction, ion and precipitate flotation of Co(II) from chloride media of 1·10^–4M initial Co(II) concentration and =0.1 have been investigated using decanoic acid and the results are compared. Organic solvents used were chloroform in the case of liquid-liquid extraction and ethanol (used as a solvent for the collector and a frother) in the case of flotation. From the results it appears that liquid-liquid extraction takes place through the formation of the complex: (CoR₂)₂(HR)₂ but flotation occurs through the formation of a surface active product which has the empirical formula CoR₂. The effects of pH and of decanoic acid concentration on the three separation processes were also investigated and the results discussed. Good agreement was observed between the experimental precipitate flotation curves and the theoretical curve calculated from the data published for Co(II) hydrolysis.     

Effects of organic and inorganic additives on flotation recovery of washed cells of Saccharomyces cerevisiae resuspended in water

Separation of microbial cells by flotation recovery is usually carried out in industrial reactors or wastewater treatment systems, which contain a complex mixture of microbial nutrients and excretion products. In the present study, the separation of yeast cells by flotation recovery was carried out using a simple flotation recovery systems containing washed yeast cells resuspended in water in order to elucidate the effects of additives (defined amounts of organic and inorganic acids, ethanol, surfactants and sodium chloride) on the cellular interactions at interfaces (cell/aqueous phase and cell/air bubble). When sodium chloride, organic acids (notably propionic, succinic and acetic acids) and organic surfactants (sodium dodecyl sulphate (SDS), cetyltrimethylammonium bromide (CTAB) and Nonidet P40) were added to the flotation recovery system, significant increases in the cell recovery of yeast hydrophobic cells (Saccharomyces cerevisiae, strain FLT-01) were observed. The association of ethanol to acetic acid solution (a minor by-product of alcoholic fermentation) in the flotation recovery system, containing washed cells of strain FLT-01 resuspended in water, leading to an increased flotation recovery at pH 5.5. Thus, the association among products of the cellular metabolism (e.g., ethanol and acetic acid) can improve yeast cell recovery by flotation recovery.     

Adsorption of N-tallow 1,3-propanediamine-dioleate collector on albite and quartz minerals, and selective flotation of albite from greek stefania feldspar ore

The adsorption behavior of tallow 1,3-propanediamine-dioleate (Duomeen TDO) collector on albite and quartz minerals is assessed through Hallimond flotation, zeta potential, and diffuse reflectance FTIR investigations, together with the species distribution of the collector. The collector performance on albite separation from a natural feldspar material is evaluated in bench scale flotation tests. The Hallimond flotation responses of the minerals as a function of pH and collector concentration indicate that albite can be selectively floated from quartz at pH 2 where the doubly positively charged collector species adsorb on albite but not on quartz. However, the zeta potential and infrared spectra reveal that the adsorption behavior of the collector is similar on both minerals. The discrepancy in the flotation and adsorption results is attributed to the coarse and fine particle size fractions, and the shorter and longer equilibration periods employed in these studies respectively. The comparable adsorption on fine particles of albite and quartz at pH 2 is explained by the interaction of ammonium ions on silanol groups by hydrogen bonding as well as electrostatic interactions. The changes in zeta potentials are in good agreement with the formation of ionic species and free molecular forms of the collector. The IR spectra show the coexistence of neutral oleic acid together with charged amine species at low pH values in accordance with the species distribution diagram. Selective flotation of albite is accomplished from a natural feldspar material with tallow diamine-dioleate collector at pH 2 using sulfuric acid, only when the feed is deslimed prior to the bench scale flotation tests. An albite recovery exceeding 85% is achieved from a feed material containing about 50% albite.     

Cationic flotation of quartz from an artificial mixture with hematite using hexylamine

The cationic flotation of quartz was carried out from an artificial mixture (1:1 by weight) of fine grained ( − 10 μm) quartz and hematite, using hexylamine acetate (HAA) and dodecylamine acetate (DAA) as collectors. Selective flotation of quartz was possible in the pH range 9–10 using HAA. The adsorption densities of DAA and HAA on quartz and hematite were measured at pH 9.8 and the relationship between the flotation behavior of both minerals and the surface coverage of collectors was established. Complete flotation of quartz and hematite required a surface coverage (θ) of DAA of about 100% at pH 9.8, while complete flotation of quartz took place at θ ⋍ 10% with HAA. The flotation behavior with DAA was explained by considering the adsorption of undissociated free amine. Zeta potential measurements were incorporated to interpret the difference in the adsorption behavior of both collectors on quartz and hematite.     

Al(III) and Cu(II) simultaneous foam separation: Physicochemical problems

In the paper, simultaneous removal of Al(III) and Cu(II) from dilute aqueous solutions by ion and precipitate flotation methods is investigated. Influence of the pH of the initial solution, the surface active collector concentration and the gas flow rate on the final removal ratio and the course of ion and precipitate flotations is presented. The results show that simultaneous flotations of Al(OH)₃ and Cu(OH)₂ insoluble species occur allowing to achieve their almost complete removal in the pH range between 7 and 9. An increase of the surface active agent concentration causes a decrease of the final removal ratio as well as of the flotation rate constant. An increase of the gas flow rate results in an increase of ion and precipitate flotation rates.     

Molecular Dynamics Simulation: Influence of External Electric Field on Bubble Interface in Air Flotation Process

Molecular dynamics(MD) simulation was performed to investigate the influence of external electric field on the vapour-liquid interface of the bubble during the process of toluene separation by air flotation. The physicochemical properties of vapour-liquid interface, surface tension, probability of a hydrogen bonding near the vapour-liquid interface and the viscosity of liquid phase caused by external electric field were analyzed. The results show that the angle between the water molecule dipole moment and the normal z axis in the vapour phase changes smaller when the external electric field is applied. The surface tension and the probability of hydrogen bonding near the vapour-liquid interface increase with the increase of electric field strength. And the viscosity also increases under an external electric field. The results confirm that the external electric field has a positive effect on the performance of bubbles in air flotation, which may provide useful guidance for the combination of electric field and air flotation technology.