浮选与沉选条件分析

根据浮选定义,考虑到浮选剂-浮选质集合体的表观密度比连续相的密度大,集合体就会发生向下运动,从而实现分离,提出了“沉选”这一名词;从浮选剂-分散相颗粒集合体的表观密度与连续相颗粒密度的大小来判断浮选剂-分散相颗粒集合体沉浮,根据浮选剂-分散相颗粒集合体的沉浮,分析了浮选条件和沉选条件,得出了各种工况下浮选剂选择的要求,从密度的角度为浮选剂的选用提供了指导。

电厂粉煤灰选沉珠对微孔隔热涂料性能的影响

为了降低微孔隔热涂料的体积密度,提升涂料的隔热性能,并实现电厂废弃物粉煤灰选沉珠的废物利用,采用粒径为0.105~0.38 mm的沉珠和粒径0.125 mm的玻璃微珠为主要原料,钠基膨润土、凹凸棒土和Si O2微粉为增塑剂,以硅溶胶为结合剂,在仅以玻璃微珠为主的隔热涂料基础上,以质量分数分别为20%、40%、60%和80%的沉珠替代玻璃微珠,研究了沉珠加入量对涂料常温力学性能、抗挠性能、导热性能和显微结构的影响。结果表明:沉珠的引入可明显降低涂料的体积密度并提高显气孔率,从而改善涂料的隔热性能,但体积密度降低的同时常温力学性能也有所下降;在0.105~0.38 mm粒径范围内,粒径的改变对抗挠性影响微乎其微。综合考虑,沉珠加入量应在60%(w)左右为宜。

选别分离技术进展

选别分离技术包括色选、磁选、电选、浮选、沉选、筛选和风选,在工业过程和三废处理过程中被广泛应用。简要介绍了几种常用的选别分离方法及其应用。

李楼铁矿重选工艺流程优化改造实践

针对李楼铁矿二段螺旋溜槽分选效果差,指标波动大的问题,开展了螺旋溜槽流程优化研究,在磨矿分级回路中,对检查分级旋流器沉砂进行了重选提精实验室试验及工业分流试验。试验结果表明沉砂重选效果良好,工业改造完成后可获得铁品位63.40%、作业回收率52.96%的铁精矿,精矿产率较改造前提高2个百分点(对原矿)。沉砂重选改造实施有效避免了二段磨矿的过磨现象,降低了后续选别作业负荷,放细了浮给粒度,新流程对矿性变化的适应性更强,使镜铁矿系统整体工艺流程更加合理,工艺技术指标更加稳定。

Separation of macro amounts of tungsten and molybdenum by precipitation with ferrous salt

In order to develop a low-cost approach for separating macro amounts of Mo and W, the effects of parameters on the separation using FeSO4 as precipitation reagent were studied. The results show that the optimum reaction temperature is 10 °C, and the separation factor does not further improve after a reaction time of 7 h. Moreover, slow dropping speed of the precipitation reagent is beneficial for improving the separation efficiency. When the H＋/W molar ratio is below 1/1, the addition of acid to a neutral solution is favorable to the separation. For the solution with an ammonium concentration below 3 mol/L, the separation factor is high due to the high W-precipitation rate. Furthermore, the method is also effective when it is applied to industrial solution containing some other impurities. All these indicate the ferrous salts have great potential for removing W from Mo on a commercial scale.

Recovery of iron from waste ferrous sulphate by co-precipitation and magnetic separation

Magnetite concentrate was recovered from ferrous sulphate by co-precipitation and magnetic separation. In co-precipitation process, the effects of reaction conditions on iron recovery were studied, and the optimal reaction parameters are proposed as follows： n（CaO）/n（Fe2＋） 1.4：1, reaction temperature 80 ℃, ferrous ion concentration 0.4 mol/L, and the final mole ratio of Fe3＋ to FJ＋ in the reaction solution 1.9-2.1. In magnetic separation process, the effects of milling time and magnetic induction intensity on iron recovery were investigated. Wet milling played an important part in breaking the encapsulated magnetic phases. The results showed that the mixed product was wet-milled for 20 min before magnetic separation, the grade and recovery rate of iron in magnetite concentrate were increased from 51.41% and 84.15% to 62.05% and 85.35%, respectively.

Enhanced catalytic activities and selectivities in preferential oxidation of CO over ceria-promoted Au/Al_2O_3 catalysts

The preferential oxidation of CO （CO‐PROX） is a hot topic because of its importance in pro‐ton‐exchange membrane fuel cells （PEMFCs）. Au catalysts are highly active in CO oxidation. Howev‐er, their activities still need to be improved at the PEMFC operating temperatures of 80–120 ＆#176;C. In the present study, Au nanoparticles of average size 2.6 nm supported on ceria‐modified Al2O3 were synthesized and characterized using powder X‐ray diffraction, nitrogen physisorption, transmission electron and scanning transmission electron microscopies, temperature‐programmed hydrogen reduction （H2‐TPR）, Raman spectroscopy, and in situ diffuse‐reflectance infrared Fourier‐transform spectroscopy. Highly dispersed Au nanoparticles and strong structures formed by Au–support in‐teractions were the main active species on the ceria surface. The Raman and H2‐TPR results show that the improved catalytic performance of the Au catalysts can be attributed to enhanced strong metal–support interactions and the reducibility caused by ceria doping. The formation of oxygen vacancies on the catalysts increased their activities in CO‐PROX. The synthesized Au catalysts gave excellent catalytic performances with high CO conversions （＆gt;97%） and CO2 selectivities （＆gt;50%） in the temperature range 80–150 ＆#176;C.

TiO2 preparation by improved homogeneous precipitation and application in SCR catalyst

Ultrasonic treatment and hydrothermal method were applied in the traditional homogeneous precipitation for nano-TiO_2 preparation, which was used as carrier material for the production of honeycomb selective catalytic reduction(SCR) catalyst. The influence rules of the two improved methods on characterization of TiO_2 samples, denitration activity and mechanical strength of honeycomb SCR catalyst samples were mainly focused on. The results indicate that the specific surface area, particle size and uniformity of TiO_2 samples are significantly improved by both of the ultrasonic and hydrothermal treatments compared with the traditional homogeneous precipitation. Also, the denitration activities of catalyst samples are enhanced by the two improved methods(the NO_x reduction ratio increases from 88.89% to 95.45% by ultrasonic homogeneous precipitation process, and to 94.12% by hydrothermal homogeneous precipitation process). On the other hand, because of good spherical shape and high particle distribution of TiO_2 sample from hydrothermal homogeneous precipitation process, the corresponding honeycomb catalyst samples get the best mechanical strength, which is even higher than that of the reference sample from commercial nano-TiO_2. So, it is concluded that the hydrothermal homogeneous precipitation can be a feasible and effective preparation method of TiO_2 carrier for the honeycomb SCR catalyst production.

Moving Behavior of an Object in Gas-Solid Fluidized Beds

The settling behavior of coarse particles in a gas-solid fluidized bed was experimentally studied by using magnetic tracer. It is well known that the calculation of terminal velocity is of interest in dense medium separation. However, this problem has not been completely solved up to now. In this work, the terminal velocity of an object mov-ing in a gas-solid fluidized bed was experimentally measured and theoretically calculated. The experimental results in-dicated that the plastic viscosity and yield stress of the bed increase as the size of fluidized particles increases, but it varies little when some coarser particles are mixed with the fluidized particles. The resistance to a rising object was an order magnitude greater than that to a settling object. The efficient buoyancy on a flaky object, which lies flatly on the gas distributor, was much less than that calculated by the Archimedes principle. The object does not always rise or set-tle with minimal projective area owing to radial motion of the fluidized particles. But in the lower part of the bed, the bar-shaped objects were likely with minimal projective area rising or settling.

改善硫精矿过滤的措施与建议

本文介绍了东乡铜矿硫精矿过滤现状,分析了硫精矿过滤,浓缩中存在的问题及原因,兼顾“全尾选硫”技改实施后的硫精矿过滤问题,提出了分级过滤,粗细分别处理的建议及措施.

Effect of the column height on the performance of liquid-solid fluidized bed for the separation of coarse slime

A liquid-solid fluidized bed separator, used for the separation of coarse slime, was developed. Test parti- cles sized in the range from 0.25 to 0.5, 0.5 to 1.0, and 0.25 to 1.0 mm were separated in the liquid-solid fluidized bed. Beds with column heights of 1200, 1500, and 1800 mm were tried. The clean coal and the railings were subsequently analyzed by float-sink testing. The results showed that the ash and yield of clean coal both decreased with increasing column height, for all three size fractions, and that the ash of the clean coal obtained from tests on the broader size fraction was less than that from the narrower sized fractions. The separation density decreased with increasing column height. The lowest E value was seen for a column height of 1500 ram, for which conditions the separation density was 1.45 g/cm3. The E value was 0.084 for the 0.25-0.5 mm fraction but the corresponding separation density was 1.48 g/cm3, and the E value 0.089, for the broader 0.25-1.0 mm fraction.

Separation and recovery of copper in Cu-As-bearing copper electrorefining black slime by oxidation acid leaching and sulfide precipitation

A new hydrometallurgical route for separation and recovery of Cu from Cu-As-bearing copper electrorefining black slime was developed. The proposed process comprised oxidation acid leaching of Cu-As-bearing slime and selective sulfide precipitation of Cu from the leachate. The effects of various process parameters on the leaching and precipitation of Cu and As were investigated. At the first stage, Cu extraction of 95.2% and As extraction of 97.6% were obtained at 80 ℃ after 4 h with initial H2 SO4 concentration of 1.0 mol/L and liquid-to-solid ratio of 10 mL/g. In addition, the leaching kinetics of Cu and As was successfully reproduced by the Avrami model, and the apparent activation energies were found to be 33.6 and 35.1 kJ/mol for the Cu and As leaching reaction, respectively, suggesting a combination of chemical reaction and diffusion control. During the selective sulfide precipitation, about 99.4% Cu was recovered as CuS, while only 0.1% As was precipitated under the optimal conditions using sulfide-to-copper ratio of 2.4:1, time of 1.5 h and temperature of 25 ℃.

Ultrasonic-enhanced selective sulfide precipitation of copper ions from copper smelting dust using monoclinic pyrrhotite

The sulfide passivation film produced on the surface seriously prevents further reaction in the process of using monoclinic pyrrhotite(MPr)to treat heavy metal ions in wastewater.Ultrasonic technology was introduced to assist MPr to recover the copper ions.XPS result proves that CuS products exist on the surface of MPr.XRD and SEM results show that the CuS on the particles’surface is stripped under ultrasonic condition.The kinetics results indicate that the reaction under both conventional and ultrasonic conditions conform to the Avrami model.The reaction process changes from diffusion control to chemical reaction control under the ultrasonic condition as the solid layer is stripped off.The presence of ultrasonic significantly reduces the acidity and temperature required for the reaction and enhances the utilization efficiency of MPr;by controlling the amount of MPr,the removal rates of copper and arsenic in copper smelting dust leachate exceed 99%and 95%,respectively.

Screening of marine fungus from Nanji Island and activity of their metabolites against pathogenic Vibrio from Pseudosciaena crocea

Seventy-eight marine fungal strains were isolated from sediment samples collected off the coast of Nanji Island, Wenzhou, Zhejiang Province, China. Antibacterial screening using the agar disc method showed that 19 of the isolated strains could inhibit at least one pathogenic Vibrio from Pseudosciaena crocea. Subsequent screening confirmed that nine strains produced antibacterial metabolites that had activity against one or several types of pathogenic Vibrio. Strain NJ0104 had the widest antimicrobial spectrum and strong activity, particularly against Fibrio parahaemolyticus-MM0810072. A preliminary study of N J0104 antibacterial metabolites demonstrated that they had thermal stability up to 80℃, ultraviolet stability up to 40 min and pH stability between 4.0-7.0. In addition, the antibacterial metabolites were readily soluble in butanol. To identify the specific strain, the ITS-5.8S rDNA regions of NJ0104 were PCR amplified and sequenced. Based on the combination of phenotypic and genotypic data, the strain was identified as Arthrinium sp.

Flotation tree analysis for recovery of sillimanite from red sediments

In this paper an attempt is made to recover sillimanite by flotation tree analysis process and conventional flotation process from non magnetic fraction of red sediments.The experimental results of both the processes are presented.The data reveal that the deslimed sample contains 33.2%(by weight) total heavy minerals and out of which the sillimanite mineral content is 3.6%(by weight).It is observed that flotation tree analysis needs 10 cells to get five output products and where as conventional flotation process needs 15 cells to recover similar grade of five output products.Thus,flotation tree analysis is not only economic process but also efficient process(to say efficient process,the tree analysis product should be higher grade).

Application of reflux classifier with closely spaced inclined channels in pre-concentrate process of fine antimony oxide particles

In this work,the reflux classifier with closely spaced inclined channels is used as the pre-concentration facility to improve the separation efficiency before the shaking table separation.Three operating parameters of reflux classifier(RC)to pre-concentrate fine(0.023−0.15 mm)tailings of antimony oxide were optimized by response surface methodology(RSM)using a three-level Box-Behnken design(BBD).The parameters studied for the optimization were feeding speed,underflow,and ascending water speed.Second-order response functions were produced for the Sb grade and recovery rate of the concentrate.Taking advantage of the quadratic programming,when the factors of feeding,underflow and ascending water are respectively 225,30 and 133 cm^3/min,a better result can be achieved for the concentrate grade of 2.31% and recovery rate of 83.17%.At the same time,70.48% of the tailings with the grade of 0.20% were discarded out of the feeding.The results indicated that the reflux classifier has a good performance in dealing with fine tailings of antimony oxide.Moreover,second-order polynomial equations,ANOVA,and three-dimensional surface plots were developed to evaluate the effects of each parameter on Sb grade and recovery rate of the concentrate.

New Method for Desalination of Seawater

The present study explores the possibility of appealing to the laws of inorganic chemistry, i.e., the rules of precipitation to desalinate seawater. Historically, the industry has been using these techniques for the preparation of some compounds. Based on these rules, using suitable salts will react with each other. The results are evident all unwanted salts including sodium chloride are removed. In fact, it is a selective precipitation as other salts which are not harmful are kept such as potassium. The other aim of the study is to reduce the current ratio desalination/power which is very high 60,000 to 80,000 cal/L for distillation （A. Payant. P. Chiliotti L. Sainte-Marie Physic Arm and Colin, Paris, France） or 4.5 kWh/m3 for RO （desalination and water reuse, California, USA） a cause of greenhouse gas except desalination using solar energy. Another aspect of this study, authors noticed rather than consume energy, regeneration or recycling of products provides energy. And in addition, the operation does not cause any pollution.

Study on the sedimentation capability of bauxite flotation concentrate

The sedimentation behaviors of bauxite flotation concentrates were investigated at different pH values and floceulant dosages. The effects of three types of flocculants （ cationic, anionic and non-ionic polyacrylamide floceulants） as well as the molecular weight of anionic flocculants on the sedimentation of concentrate were studied. It is shown from the experimental results that at the pH 7.0, best sedimentation capability is reached when anionic polyacrylamide flocculant （molecular weight 14 million） is added and the optimal dosage is 30 g/t.