脂肪酸作捕收剂白云石浮选规律及其机理研究

通过单矿物浮选试验,研究了饱和脂肪酸作捕收剂时白云石的浮选规律.以肉豆蔻酸、月桂酸为捕收剂时,酸性条件下药剂用量相对较小,当回收率达到70%时,酸、碱性条件下的药剂用量相差分别为3.72,5.64倍.FTIR,XPS测试结果表明在酸、碱性条件下,捕收剂均可以吸附于矿物表面,SEM测试表明在酸性条件下泡沫产品表面存在大量固体附着物.机理研究表明,碱性条件下,捕收剂与白云石之间以化学吸附为主.在酸性环境中,脂肪酸类捕收剂主要以不溶于水的脂肪酸固体的形式在矿物表面形成固体附着物,进而导致矿物表面疏水,使得在酸性条件下白云石也具有较好的可浮性.     

Electron bandstructure of kaolinite and its mechanism of flotation using dodecylamine as collector

The bulk electronic structure of kaolinite (001) plane was studied with quantum mechanical calculations. The CASTEP parameterization of ultrasoft pseudopotentials without core corrections was used to optimize the structure of kaolinite bulk and slab models. The results show that Fermi energy of kaolinite (001) plane is 3.05 eV, and the band gap is 4.52 eV. The partial density of states (PDOS) of kaolinite (001) plane indicates that Al—O and Si—O bonds on the mineral surface are highly polar. The oxygen atoms of hydroxyl groups in surface layer are capable of forming hydrogen bond with the head group of cationic collectors. The properties of dodecylamine (DDA) cation were also calculated by density function theory (DFT) method at B3LYP/6-31G (d) level for illuminating the flotation processes of kaolinite. Besides the electrostatic attraction, the mechanism between kaolinite and DDA is found to be hydrogen bonds under acidic condition. Foundation item: Project(2005CB623701) supported by the Major State Basic Research and Development Program of China; Project(50874118) supported by the National Nature Science Foundation of China; Project(2007B52) supported by the Foundation for the Author of National Excellent Doctoral Dissertation of China     

Adsorption of sodium oleate at the microfine hematite/aqueous solution interface and its consequences for flotation

The adsorption of sodium oleate(NaOL) at the microfine hematite/aqueous solution interface was investigated in this paper. Experimental research indicated that negative effects stemmed from the dissolution of the microfine hematite(D50=19.21 μm) could be effectively eliminated via the appropriate dosage of NaOL at alkali pH conditions. Solution chemistry calculation and adsorption test results indicated that RCOO^- and(RCOO)₂^2- ions were responsible for microfine ...     

Effect and mechanism of siderite on reverse anionic flotation of quartz from hematite

Reverse flotation technology is one of the most efficient ways to improve the quality and reduce impurity of iron concentrate. Mineral processors dealing with hematite face a challenge that the flotation results of reverse flotation of hematite are poor in presence of siderite using fatty acid as collector, starch as depressant of iron minerals and calcium ion as activator of quartz at strong alkaline pH. In this work, the effect of siderite on reverse anionic flotation of quartz from hematite was investigated. The effect mechanism of siderite on reverse flotation of hematite was studied by solution chemistry, ultraviolet spectrophotometry(UV) and Fourier transform infrared spectroscopy(FTIR). It was observed that siderite had strong depressive effect on quartz in flotation using sodium oleate as collector, corn starch as depressant of iron minerals and calcium chloride as activator of quartz at strong alkaline pH. The starch was adsorbed onto calcium carbonate by chemical reaction which was formed by CO~(2-)_3 from siderite dissolution and Ca~(2+) from calcium chloride as activator of quartz and precipitated on the surface of quartz, which resulted in improving the hydrophilic ability of quartz.     

磷矿捕收剂油酸钠的表面张力研究

通过滴体积法测定了不同温度、pH和盐浓度等条件下油酸钠水溶液的表面张力,测定了油酸钠-吐温80复配体系水溶液的表面张力,初步研究了油酸钠的表面活性以及吐温80对油酸钠的增效作用,为选矿作业提供了理论支持.     

Coal flotation using wash oil as a new type of collector

The use of wash oil as a coal collector is proposed to overcome the disadvantages of regular collectors in coal slime flotation. These disadvantages include high price, limited sources and high consumption. The effect of additives on flotation was studied and an innovative "one rough separation-one cleaning separation" flotation technology was developed. The experimental results show that the clean coal ash content decreases by about 1.36% and the clean coal yield declines by around 10% with the application of the depressant. There is an increase of 3.76% in the yield of clean coal and a decrease of 0.40% in the ash content caused by utilizing a dispersant. An ultimate product having an ash content of 10.78% and yield of 70.12% can be attained using a combination of dispersant and depressant. The use of this new technology decreases the ash content by 1.21%, decreases the yield by 2.80% and an increases the coal flotation perfect index by 2.03%. Compared to common flotation, the utilization of the new technology reduces ash by 0.17%, increases yield by 5.3% and increases perfect index by 4.18%.     

Effect of butanol on flotation separation of quartz from hematite with N-dodecyl ethylenediamine

In order to investigate the effect of butanol on quartz flotation when N-dodecyl ethylenediamine(ND)was used as collector, single mineral flotation and artificial mixed mineral(hematite and quartz were mixed at a mass ratio of 3:2) separation were conducted in the laboratory. Experimental results indicated that addition of butanol could improve the collecting performance of ND on quartz and enhance the floatability of quartz. Best flotation recovery of quartz was obtained when butanol was mixed with ND at a mass ratio of 1:1. Moreover, the molecular structure of alcohols had a significant effect on mineral recovery. Best separation efficiency could be obtained when tert-butanol was added as it had the largest cross-sectional area. Zeta potential measurements indicated that alcohols could strengthen electrostatic adsorption between quartz and collector. Molecular dynamic simulations revealed that co-adsorption of alcohols along with ND had taken place on the quartz surface, and ND/tert-butyl combinations were more easily absorbed on the quartz surface.     

Effect of depressants on flotation separation of magnesite from dolomite and calcite

The flotation separation of magnesite from calcium-containing minerals has always been a difficult subject in minerals processing. This work studied the inhibition effects of carboxymethyl cellulose(CMC),sodium lignosulphonate, polyaspartic acid(PASP) and sodium silicate on flotation behaviors of magnesite, dolomite and calcite, providing guidance for the development of reagents in magnesite flotation.The micro-flotation results showed that among these four depressants, sodium silicate presented...     

Influences of collector DLZ on chalcopyrite and pyrite flotation

The interaction mechanism of collector DLZ in the flotation process of chalcopyrite and pyrite was investigated through flotation experiments, zeta potential measurements and infrared spectrum analysis. Flotation test results indicate that DLZ is the selective collector of chalcopyrite. Especially, the recovery of chalcopyrite is higher than 90% in neutral and weak alkaline systems, while the recovery of pyrite is less than 10%. When using CaO as pH regulator, at pH=7-11, the floatability of pyrite is depressed and the recovery is less than 5%. Zeta potential analysis shows that the zeta potential of chalcopyrite decreases more obviously than that of pyrite after interaction with DLZ, confirming that collector DLZ shows selectivity to chalcopyrite and pyrite. And FT1R results reveal that the flotation selectivity of collector DLZ is due to chemical absorption onto chalcopyrite surface and only physical absorption onto pyrite surface.     

Insights into the influence of temperature on the adsorption behavior of sodium oleate and its response to flotation of quartz

Temperature affects the flotation of quartz in the calcium/sodium oleate(NaOL)system,while there is a lack of understanding of its potential mechanism.Therefore...     

Effect of sodium pyrophosphate on the flotation separation of chalcopyrite from galena

The effect of sodium pyrophosphate (SPH) on the separation of chalcopyrite from galena was examined through flotation, adsorption, electrokinetic studies and infrared spectral analysis. Differential flotation tests indicate that satisfactory separation can be achieved within the pH range from 2.5 to 6 using SPH to depress the galena, but not the chalcopyrite when O-isopropyl-N-ethyl thionocarbamate (IPETC) is used as the collector. The electrophoretic mobilities of both the minerals dramatically become negatively charged following SPH adsorption in the pH range from 2.5 to 12. The infrared spectral analysis suggests that chemical adsorption occurs on galena surface treated by SPH, indicating that a chelate complex has formed. At weakly acidic pH values, the adsorption density of IPETC onto galena is significantly reduced in the presence of SPH. However, the amount of IPETC adsorbed onto chalcopyrite almost remains at the same level. Since the observed adsorption density of IEPTC onto chalcopyrite is quite high compared to galena, the observed flotation results are explained. A possible mechanism for the interaction between the two sulphide minerals and SPH is discussed.     

十二烷基苯磺酸钠对浆液浆膜及浆纱性能的影响

本文着重研究了十二烷基苯磺酸钠对淀粉液的浆液、浆膜及浆纱性能的影响，并讨论了作用机理．     

Effect of some operational variables on bubble size in a pilot-scale mechanical flotation machine简

This work aims to provide a relationship of how the key operational variables of frother type and impeller speed affect the size of bubble （D32）. The study was performed using pilot-scale equipment （0.8 m^3） that is up to two orders of magnitude larger than equipment used for studies performed to date by others, and incorporated the key process variables of frother type and impeller speed. The results show that each frother family exhibits a unique CCC95-HLB relationship dependent on n （number of C-atoms in alkyl group） and m （number of propylene oxide group）. Empirical models were developed to predict CCC95 from HLB associated with other two parameters a and ft. The impeller speed-bubble size tests show that D32 is unaffected by increased impeller tip speed across the range of 4.6 to 9.2 m/s （representing the industrial operating range）, although D32 starts to increase below 4.6 m/s. The finding is valid for both coalescing and non-coalescing conditions. The results suggest that the bubble size and bubble size distribution （BSD） being created do not change with increasing impeller speed in the quiescent zone of the flotation.     

Activation flotation and mechanism of lime-depressed pyrite with oxalic acid

Flotation tests,contact angle measurements,infrared spectrum analyses,X-ray analyses and computer simulation were carried out in order to study the activation mechanism of lime-depressed pyrite with ox...     

Effects of sodium hexmetaphosphate on flotation separation of diaspore and kaolinite

1INTRODUCTION ThebauxiteinChinaismainlyofdiasporite type,withhighcontentofAl2O3butlowmassra tioofAl2O3toSiO2.Themainsiliceousminerals ofbauxitearekaolinite,illiteandpyrophyllite[1].Inordertoutilizethebauxiteeffectively,anewflotationdesilication Bayermethodwasdeveloped toproducealumina.Thepurposeofflotationdesil icationistoremovethesilicafromthebauxiteandtoincreasethemassratioofAl2O3toSiO2.Funda mentalresearchofreverseflotationdesilicationhas beenpaidmoreattentionduetoitsadvantageover…     

颗粒尺寸与药剂性质对胶磷矿浮选过程的影响

通过磷矿颗粒的分级浮选、药剂对比及组合浮选对湖北保康钙质磷矿和大峪口硅钙质磷矿进行了系统研究.结果表明:分级后粒径为-65μm的小颗粒磷矿更有利于反浮选,且保康磷矿反浮选效果优于大峪口磷矿;复合药剂和酸性抑制剂均能改善保康钙质磷矿浮选效果,最终磷精矿品位达到36.14%,磷回收率为96.10%;药剂表面张力降低能增强药剂对磷矿颗粒的湿润.最后,通过测量电动电位和亲水亲油平衡值,对浮选过程效率进行了分析,并对浮选机理进行了讨论.     

NOM组分对O3降解水中微污染有机物的影响

采用一系列不同截留分子量的超滤膜将提取的天然有机物(NOM)滤分为6种组分(NOM10K、NOM5K-10K、NOM3K-5K、NOM1K-3K、NOM500-1K、NOM500)组分,并研究了这6种NOM组分对臭氧(O3)氧化降解水中两种典型微污染有机物(双酚A和硝基苯)的影响.结果表明:对于与O3反应活性较高的有机物双酚A(BPA),NOM各组分的引入使得O3去除BPA效能有所下降;对于与O3反应活性较低的有机物硝基苯(NB),高分子量范围的NOM组分(NOM10K、NOM5K-10K、NOM3K-5K、NOM1K-3K)的存在能强化O3的自由基链式分解反应,从而促进O3对硝基苯的去除.低质量浓度的NOM对O3氧化降解水中有机物的影响与NOM的特性(所含的官能团的类型和数量)以及目标有机物与O3的反应活性有关.     

Flocculation performance and mechanism of hydroxamate flocculants on synthetic hematite or goethite suspension

Suitable amounts of Al(OH)3, Na OH and synthetic hematite or goethite were taken to be digested under the simulated condition of the Bayer process and subsequently diluted with simulative Bayer red mud lotion, then the synthetic hematite or goethite suspension was obtained. The flocculation effect of self-made modified poly(acrylic acids) flocculants containing hydroxamic acid groups(abbreviated as HPAA) on the synthetic hematite or goethite suspension was studied. The experimental results show that with the increase of the dosages of added flocculants, the average settling rate of the synthetic hematite or goethite suspension in the first 1min speeds up, the supernatant solids decrease. It could also be found that there is generally a decrease in the average settling rate of the synthetic hematite or goethite suspension in the first 1 min with increasing solid content of the suspension. When the solid content of hematite or goethite of the suspension is 50 g/L with 240 g/t dosage of HPAA, HPAA has a better flocculation effect on the synthetic goethite suspension than on the synthetic hematite suspension. The adsorption mechanism of HPAA on the surface of hematite or goethite was investigated by Fourier transform infrared spectroscopy(FT-IR) and X-ray photoelectron spectroscopy(XPS).All the results suggest that HPAA is adsorbed on the hematite or goethite surface by a chemisorption, and it has a stronger adsorption on the goethite surface than on the hematite surface.     

Numerical investigation on the caving mechanism with different standard deviations of top coal block size in LTCC

The size distribution of the broken top coal blocks is an important factor, affecting the recovery ratio and the efficiency of drawing top coal in longwall top coal caving(LTCC) mining panel. The standard deviation of top coal block size(dt) is one of the main parameters to reflect the size distribution of top coal. To find the effect of dton the caving mechanism, this study simulates experiments with 9 different dtby using discrete element software PFC. The dtis divided into two stages: uniform distribution stage(UDS) whose dtis less than 0.1(Schemes 1–5), and nonuniform distribution stage(NDS) whose dtis more than 0.1(Schemes 6–9). This research mainly investigates the variation of recovery ratio, drawing body shape,boundary of top coal, and contact force between particles in the two stages, respectively. The results showed that with the increasing dt, the recovery ratio of the panel increases first and then decreases in UDS. It is the largest in Scheme 3, which mainly increases the drawing volume at the side of starting drawing end. However, the recovery ratio decreases first and then increases quickly in NDS, and it is the largest in Scheme 9, where the drawing volume at the side of finishing drawing end are relatively higher. In UDS, the major size of top coal is basically medium, while in NDS, the size varies from medium to small, and then to large, with a distinct difference in shape and volume of the drawing body. When the major size of top coal is medium and small, the cross-section width of the initial boundary of top coal at each height is relatively small. Conversely, when the top coal size is large, the initial boundary of top coal has a larger opening range, the rotating angle of lower boundary is relatively small in the normal drawing stage, which is conducive to the development of drawing body and reduces the residual top coal, and the maximum particle velocity and the particles movement angle are both larger. This study lays a foundation for the prediction of recovery ratio, and suggests that the uniform top coal is more manageable and has a larger recovery ratio.     

Mechanism study on flotation separation of molybdenite from chalcocite using thioglycollic acid as depressant

Effects of collectors(butyl xanthate(BX), O-isopropyl-N-sulfur ethyl carbamate(Z-200) and emulsified kerosene), dereagent(sodium sulfide) and depressant thioglycollic acid(TGA) on the flotation of chalcocite and molybdenite were investigated through flotation. The first principle theory was adopted to understand the difference of their surfaces and reaction between minerals and reagents. Results of flotation tests revealed that selectivity of emulsified kerosene is the best of three collectors in separation of chalcocite and molybdenite, though the others also display excellent collecting properties. Sodium sulfide can effectively remove collectors adsorbed on chalcocite surface, and TGA is an effective depressant of chalcocite at pH 8-9. Through first principle study, molybdenite displays relatively stronger covalence property while bonding interaction between copper atoms in chalcocite enhanced its ionicity. Bonding interaction is weaker in reaction of TGA and molybdenite, so it shows higher hydrophobicity and better flotability. Therefore, TGA is an effective inhibitor in the separation.