首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献，搜索用时 46 毫秒
1.
The maximum flotation response for three naturally occurring calcium minerals, apatite, calcite and fluorite with sodium oleate collector correlated directly with the minimum interfacial tension of the air/solution interface. For fluorite and apatite the minimum surface tension occurred about the mid-pH region and was attributed to the formation of pre-micellar associated species in solution. In the case of calcite the minimum was observed at high pH since the presence of high concentrations of calcium ions in solution appeared to reduce the concentration of amphililic species in the low and mid-pH regions.Microelectrophoresis data demonstrated that the three minerals acquired a negative charge in sodium oleate solution, resulting from adsorption of oleate species on the mineral surfaces.The flotation behaviour of the systems were shown to be related to the species distribution diagrams suggesting that the role of the acid soap dimer, soap dimer, molecular and lattice species could make a significant contribution to the character and composition of the interfacial films.High flotation response was explained by strong adhesion between the hydrophobic particle and bubble. It was suggested that the reduction in surface tension may not be the major factor contributing to the flotation efficiency but indicated the presence of associated surfactant species in solution which could also synergistically adsorb at the solid/liquid interface, increasing the hydrophobic character of the mineral surface. This would maximize the magnitude of the contact angle and hence the strength of the adhesion between particle and bubble. This adsorption behaviour is not in general agreement with conventionally non-hydrolyzable collector theory which is usually based on electrostatic models.  相似文献   

2.
A study has been made of the adsorption of sodium silicate by calcite, fluorite and barite and the effect that this adsorption has on the flotation of these minerals with oleic acid. The results show that sodium silicate depresses these minerals by preventing oleate species from reacting with surface sites. This effect is independent of the total silica concentration. Aged sodium silicate solutions do not produce markedly different results to those obtained with fresh solutions.The concentration of the sodium silicate solutions was generally such that the total silica concentration was below that in equilibrium with amorphous silica. Under these conditions the solutions contained no polymeric silica species and the mechanism of silica adsorption can be generally attributed to interactions of monosilicate ion and monosilicic acid with surface sites.  相似文献   

3.
本文以油酸钠作为捕收剂,研究了磷酸氢二钠、柠檬酸和硅酸钠等抑制剂对粉石英与红柱石浮选分离效果的影响.结果表明,磷酸氢二钠是红柱石与粉石英浮选分离的一种优良的抑制剂;在其最佳浓度0.47×10-2 mol /L,浮选液pH值为8.5时,粉石英与红柱石浮选回收率差高达47.86％.红外光谱及Zeta电位分析结果表明,油酸钠对红柱石兼有物理和化学吸附作用,对粉石英仅有物理吸附作用,因而对红柱石有更强的捕收能力;磷酸氢二钠对粉石英表面起解吸作用,能有效抑制粉石英起浮,从而实现粉石英与红柱石的分离.  相似文献   

4.
The interaction of oleic acid with fluorite, calcite and barite has been studied using solubility, oleate abstraction, electrophoretic mobility and Hallimond-tube flotation measurements. Abstraction of oleate from aqueous solution corresponds to the precipitation of the metal oleate. Multilayers of metal oleate inhibits the dissolution of the minerals and prevents true equilibrium from being obtained. Flotation is not only dependent on the amount of oleate abstracted but also on the strength of adhesion of the precipitated metal oleate to the minerals. Selectivity between the flotation of calcite, fluorite and barite is unlikely to be obtained by varying the pH because similar responses are observed.  相似文献   

5.
Separation of Mussorie rock phosphate (P2O5 = 20%) from Uttar Pradesh, India, containing pyrite, calcite and other carbonaceous impurities by flotation has been successfully attempted to upgrade the phosphate values. Based on Hallimond cell flotation results of single and synthetic mineral mixtures of calcite and apatite using oleic acid and potassium phosphate, conditions were obtained for the separation of calcite from apatite which is considered to be the most difficult step in the beneficiation of calcareous phosphates. Further studies using 250 g of the mineral (?60 +150 and ?150 mesh fractions, deslimed) in laboratory size Fagergren subaeration machine employed a stagewise flotation viz. carbonaceous materials using terpineol, pyrite using potassium-ethyl xanthate and calcite using oleic acid respectively. Separation was, however, found to be unsatisfactory in the absence of a depressant.Among starch, hydrofluosilicic acid and dipotassium hydrogen phosphate, which were tried as depressants for apatite in the final flotation stage, dipotassium hydrogen phosphate proved to be superior to others. However, the tests with the above fractions did not yield the required grade. This was possibly due to insufficient liberation of the phosphate mineral from the ore body and different experimental conditions due to scale up operations. Experiments conducted using ?200 mesh deslimed fractions has yielded an acceptable grade of 27.6% P2O5 with a recovery of about 60%. The results have been explained in terms of the specific adsorption characteristics of phosphate ions on apatite and the liberation size of the mineral.  相似文献   

6.
The effects of Na2SiO3, Na3PO4, Na4P2O7, (NaPO3)6, quebracho, tannic acid and S 808 (sulphonated product of rough phenantrene) on the floatability of the following five pure minerals: scheelite, calcite, fluorite, garnet and quartz, with sodium oleate as collector were investigated in detail as well as the role of pH on these effects. The results obtained indicate that Na4P2O7 and (NaPO3)6 were effective modifiers for the selective flotation of scheelite. The results of the batch flotation tests on mixtures of these minerals showed that the recovery of scheelite from scheelite-silicate mixtures (31% WO3) with (NaPO3)6 or Na4P2O7 increased by 20% as compared with sodium silicate and the WO3 grade of the concentrate by 5%. At room temperature, the scheelite-calcium mineral mixtures could not be separated with sodium silicate. In the separation of these mixtures with the phosphate modifiers, a concentrate grade of 47–60% WO3 was obtained at 70–90% recovery. This showed that the flowsheet of the selective flotation of scheelite with phosphate modifiers may replace the conventional Petrov's process.  相似文献   

7.
The respective effects of phosphate modifiers on the solubility of calcium minerals in water, on the surface charge of the minerals and on the adsorption of the phosphates and of sodium oleate on the mineral surface were examined. The Auger spectra and the infrared spectra of the minerals treated with these reagents were also investigated. The ability of the phosphates to complex metal ions was determined by nephelometric titration. The structures of the minerals and their effects on their floatability, as well as structures of the phosphates and their effects on the complexation power were discussed. A mechanism of depression of the calcium minerals through the selective complexing dissolution of calcium ions from the mineral surface was derived and explains the higher selectivity obtained in scheelite flotation when (NaPO3)6 or Na4P2O7 are used as modifiers.  相似文献   

8.
Acidification of solutions of oleate salts forms emulsions of oleic acid. It was found that these emulsions produce a different adsorption behaviour on different size fractions of the same mineral. At low oleate concentrations, for the finer fractions, adsorption at acid pH was higher than chemisorption at pH = 7.5; adsorption was lower for the coarser, flotation-size fractions. Therefore, the conclusions obtained in acid solutions for the adsorption of oleate on fine minerals cannot be applied to flotation-size minerals.At low oleate concentrations there is a good correlation between oleate adsorption and hematite flotation. This does not hold for oleate concentrations > 5· 10?5M, where there is poor flotability in the acid region, although the adsorption of oleic acid is very high. This is attributed to the disordered character of the layer of cooperatively adsorbed oleic acid.  相似文献   

9.
Microelectrophoresis technique was used to study the electrokinetic properties of some apatites and calcite. The results indicate that similar to oxide minerals, H+ and OH? ions function as potential-determining ions for apatite and calcite. However, because of their variable compositions, the apatites from different deposits showed different i.e.p. values ranging from pH 3.5 to 6.7, while the i.e.p. of calcite occurred at pH 8.2.Study of the effect of lattice-forming ions on the zeta potential indicates that calcium ions produce specific ionic adsorption effects on apatites, whereas they are potential-determining ions for calcite. On the other hand, as expected, phosphate and carbonate ions function as potential-determining ions for apatite and calcite, respectively.The experimental data suggest that the zeta potential of apatite is a function of mineral—water contact time. The degree of variation in zeta-potential values appears to be influenced by the electrolytic environment of the apatite suspension.  相似文献   

10.
国内矿物治理重金属废水研究进展与展望   总被引：7，自引：4，他引：3  
综述了我国利用天然矿物治理重金属废水方面的研究新成果。天然铁的硫化物、天然铁锰的氧化物、方解石与磷灰石等具有良好的表面吸附与氧化还原化学活性;不同介质中它们能不同程度地表现出对Cr^6 、Pb^2 、Hg^2 、Cd^2 等重金属离子的吸附作用,可广泛用于重金属废水处理。矿物吸附重金属离子机理的研究表明,矿物对重金属的吸附是矿物表面与无机重金属离子之间的表面作用过程,包括矿物表面功能基与重金属离子的配位反应、矿物表面氧化还原反应和沉淀转化作用,以及矿物表面离子交换吸附作用等。  相似文献   

11.
Sedimentary phosphates contain-besides the phosphate minerals-, various associated gangue minerals such as: clays, silica, calcareous minerals (mainly calcite and dolomite), carbonaceous matter, iron oxides and/or pyrite. The common practiced flow-sheets for concentrating these types of phosphate ores consist of a combination of various mineral processing units such as: crushing and screening, attrition, washing, magnetic separation, and/or flotation. However, none of these combinations was successfully efficient to upgrade the calcareous ores because of the close similarity of the physical properties (density, particle size, particle shape, etc.) as well as the surface physico-chemical properties of the carbonate and phosphate minerals. For the last five decades extensive efforts have been spent to adopt flotation for separating carbonates from phosphate ores. These efforts include thermodynamic analysis, modification of the technique, controlling the pulp environment, and finding new reagents that can specifically differentiate between carbonates and phosphates.This paper reviews some of the published work on the separation of carbonates from phosphate ores by flotation and presents the flotation results of phosphate ore samples different in their physical properties and mineralogical composition. The results obtained reflect the effect of ore nature on the flotation performance and the reagents consumption.  相似文献   

12.
山东蒙阴金伯利岩组成矿物以蚀变矿物为主,X射线粉晶衍射仪鉴定结果显示无矿金伯利岩矿物组分为方解石、白云石、石英、钙锆钛矿,标志性矿物为白云石和钙锆钛矿;贫矿金伯利岩矿物组分为蛇纹石、方解石、钙铝榴石、磁铁矿和金云母,标志性矿物为钙铝榴石;富矿金伯利岩矿物组分为蛇纹石、方解石、绿泥石、磷灰石、磁铁矿和金云母,标志性矿物为绿泥石和磷灰石。采用X射线粉晶衍射仪鉴定金伯利岩蚀变矿物组合,寻找蚀变矿物组分变化与金伯利岩含矿性的关系,利用标志性的蚀变矿物判断金伯利岩无矿、贫矿还是富矿,是非常有意义的。  相似文献   

13.
The influence of an ultrasonic field frequency of 22 kHz and intensity of 0.5 W/cm2 has been examined on the flotation of barite, fluorite and quartz as well as on their ability to adsorb dodecyl- and cetylsulphates. The tests affected the flotation of pure minerals in a Hallimond tube as well as the flotation of a natural barite-fluorite ore. It has been found that ultrasonic pretreatment of minerals causes an increase in the flotation rate of barite and a decrease in the flotation rate of fluorite. Ultrasonic pretreatment of the natural barite-fluorite ore before its flotation is the most advantageous. In this case it is possible to obtain concentrates of barite composed of a low amount of CaF2. This may be explained by the different effects of ultrasonic vibrations on barite and fluorite which cause some improvement of the selectivity of their flotation separation.For a full explanation of these results the effects of ultrasonic pretreatment of the minerals on their adsorption properties and surface topography have been investigated, as well as the direct influence of ultrasound on the adsorption process.  相似文献   

14.
Both froth flotation and centrifugal concentration were used to pre-concentrate the oil sands froth treatment tailings prior to the recovery of heavy minerals (titanium and zirconium minerals). Over 90% of the heavy minerals were recovered into a bulk flotation concentrate that was about 50% of the feed mass at 85 °C without any reagents. The same recoveries were obtained at 50 °C with the addition of NaOH and/or sodium oleate. However, the flotation concentrate also recovered over 90% of the residual bitumen and much of the clays/slimes. Subsequent treatment of the flotation concentrate such as dewatering and bitumen removal would be difficult due to these residual bitumen and clays. On the other hand, a SB40 centrifugal concentrator recovered over 85% of the heavy minerals but less than 30% of the residual bitumen. With improved liberation the recovery of the residual bitumen into the concentrate could be further reduced. The particle sizes of the SB40 concentrates were also larger than the flotation concentrates, making subsequent processing much easier.  相似文献   

15.
Electrokinetic and flotation studies on apatites and calcite show that under certain conditions these minerals are floatable with dodecylamine chloride (DDACl) and the possible mode of DDACl adsorption is due to Coulombic and Van der Waals forces. The results indicate hemi-micelle formation of dodecylamine ions and suggest involvement of neutral molecular amine in the hemi-micelle structure, the critical hemi-micelle concentration being influenced by the nature of charge at the mineral surface.  相似文献   

16.
This study deals with the effect of mechanical treatment, using vibrating mill, on the mineralogy and structure of apatite and associated gangue minerals (dolomite, calcite, quartz, pyrite and gypsum) in Abu-Tartour phosphate ore, Egypt. The evolution of mineralogy, crystallinity and deformation mechanism were evaluated with different techniques (XRD, DTA, TGA and FT-IR). Data obtained using these techniques give a good picture about the mechanochemical behavior of the different components in the ore. X-ray diffraction (XRD) indicated that the mineralogy has been changed quantitatively at short time grinding (30 min). After 45 min of grinding, the sample contained mainly carbonate apatite, quartz and pyrite. On the other hand, dolomite mineral disappeared, while calcite was partially transformed into aragonite. This transformation increased with increasing grinding time. Both Fourier Transform Infrared (FT-IR) and differential thermal analysis (DTA) analyses revealed that remarkable changes in the structural groups have occurred after 45 min of grinding. After 75 min of grinding, the carbonate in the apatite mineral partially decomposed and tricalcium phosphate formed instead. The formation of that simple form (tricalcium phosphate) may be another reason, besides surface area, for increasing the reactivity of phosphate ore by grinding. Scanning electron micrographs (SEM) revealed some idea about the grinding mechanisms of Abu-Tartour phosphate using vibrating mill. They indicate that the different minerals are ground differently. The apatite minerals are ground mostly by abrasion mechanism, while the carbonate minerals are ground mostly by compression. Also, these minerals are ground with different rates, where dolomite is ground faster than calcite, which are referred to the crystal lattice.  相似文献   

17.
The flotation of chalcopyrite and sphalerite from copper and copper-zinc ores has been achieved without using thiol-type collectors. Typically, a sulfide ore sample is first treated with sodium sulfide either during grinding or during the preflotation conditioning period, and then the chalcopyrite is floated with frother alone. With a copper-zinc ore, sphalerite is subsequently floated from the chalcopyrite tailings by activating it with copper sulphate. Results of the collectorless flotation tests are comparable to those obtained by using thiol collectors. The mechanisms of selective collectorless flotation are discussed on the basis of differences in the solubilities of sulfide minerals.  相似文献   

18.
The mechanism of flotation of calcium tungstate with non-complexing ionic surfactants has been examined. With fatty-acids, precipitation of the calcium soap sets in at very low concentrations. None of the conventional reagents alone provides sufficient selectivity to permit separation of scheelite from calcite.As an example of a possible chelating collector for tungstate minerals, 4-tertiary butyl catechol (4 TBC) was examined. Although such reagents are, indeed, adsorbed and induce floatability, they are useless as collectors, for several reasons. For example, 4TBC was found (unexpectedly) to be more strongly adsorbed by calcite than by scheelite; furthermore, soluble tungsten complexes were also formed.  相似文献   

19.
The effects of oxidation potential (Eh) and zinc sulphate on the separation of chalcopyrite from pyrite were investigated at pH 9.0. The flotation recovery of these minerals is Eh dependent with maximum separation obtained at 275 mV SHE. Zinc sulphate addition improved this mineral separation at an Eh value of 275 mV by selectively depressing pyrite flotation. A different result was obtained at lower Eh values where zinc sulphate addition improved chalcopyrite flotation but had no or little effect on pyrite flotation. These opposite effects of zinc sulphate on mineral flotation were reconciled by examining the surface species of these minerals. The selective depression of pyrite flotation by zinc sulphate was also confirmed in the flotation of two copper ores.  相似文献   

20.
The ability of O-isopropyl-N-ethyl thionocarbamate (IPETC), O-isobutyl-N-ethoxycarbonyl thionocarbamate (IBECTC) and butyl ethoxycarbonyl thiourea (BECTU) collectors to increase the flotation of the sulphide minerals, chalcopyrite, galena and pyrite, has been studied. For each collector, the flotation characteristics of these minerals, flotation rate constant and flotation recovery maximum, have been calculated from the flotation data and compared as a function of pH and collector concentration. Overall, the flotation performance of these collectors is stronger for chalcopyrite than for galena and pyrite. Flotation increases with collector concentration and decreasing pH values. For chalcopyrite, the collector performances of BECTU are slightly better than those of IPETC but far superior to those of IBECTC, especially at high pH values or at low collector concentrations. The flotation performance of these collectors has been shown to be in good agreement with the amount of collector adsorbed at the mineral surface. The affinity of BECTU for the various minerals has been calculated using a multilayer adsorption model.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号