粉石英与红柱石的浮选分离机理研究

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.     

Molar refraction of quartz family minerals

Different polymorphs of silica and the opals exhibit significant variations in densities. The paper discusses and correlates the variations in the molar refraction with density. It emerges that in different polymorphs of silica, the increase in density involves a corresponding increase in the characteristic dispersion frequencies leading to a decrease in the molar refraction. The variation of the molar refraction with density can be represented in terms of an elementary formula. The variation of the molar refraction of opals with the water content in them is also accounted for.     

Selective flotation of scheelite from calcium minerals with sodium oleate as a collector and phosphates as modifiers. I. Selective flotation of scheelite

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.     

Removal of lead minerals from copper industrial flotation concentrates by xanthate flotation in the presence of dextrin

Potato starch and dextrins resulting from thermolysis of potato starch in the absence of reagents and presence of -amino acids are promising depressants for separation of lead and copper minerals present in the Polish industrial copper concentrates. The polysaccharides were used for differential xanthate flotation of the final industrial concentrates produced by flotation with sulfhydryl collectors in the absence of depressants. The polysaccharides depressed galena and provided froth concentrate rich in chalcocite and other copper minerals as well as cell product containing lead minerals. The best results of separation were obtained in the presence of plain dextrin prepared by a thermal degradation of potato starch. The industrial concentrate containing 18.5% Cu and 5.5% Pb was divided into a froth product containing 38.1% Cu with 77% recovery of copper and a cell product assaying 7.3% Pb with 83% recovery of lead. It was accomplished using 2500 g/t of dextrin, 50g/t of potassium ethyl xanthate, and 50 g/t of frother (α-terpineol). The pH of flotation was 8.0–8.2.     

Uranium co-precipitation with iron oxide minerals

In oxidizing environments, the toxic and radioactive element uranium (U) is most soluble and mobile in the hexavalent oxidation state. Sorption of U(VI) on Fe-oxides minerals (such as hematite [α-Fe₂O₃] and goethite [α-FeOOH]) and occlusion of U(VI) by Fe-oxide coatings are processes that can retard U transport in environments. In aged U-contaminated geologic materials, the transport and the biological availability of U toward reduction may be limited by coprecipitation with Fe-oxide minerals. These processes also affect the biological availability of U(VI) species toward reduction and precipitation as the less soluble U(IV) species by metal-reducing bacteria.To examine the dynamics of interactions between U(VI) and Fe oxides during crystallization, Fe-oxide phases (containing 0.5 to 5.4 mol% U/(U + Fe)) were synthesized by means of solutions of U(VI) and Fe(III). Wet chemical (digestions and chemical extractions) and spectroscopic techniques were used to characterize the synthesized Fe oxide coprecipitates after rinsing in deionized water. Leaching the high mol% U solids with concentrated carbonate solution (for sorbed and solid-phase U(VI) species) typically removed most of the U, leaving, on average, about 0.6 mol% U. Oxalate leaching of solids with low mol% U contents (about 1 mol% U or less) indicated that almost all of the Fe in these solids was crystalline and that most of the U was associated with these crystalline Fe oxides. X-ray diffraction and Fourier-transform infrared (FT-IR) spectroscopic studies indicate that hematite formation is preferred over that of goethite when the amount of U in the Fe-oxides exceeds 1 mol% U (∼4 wt% U). FT-IR and room temperature continuous wave luminescence spectroscopic studies with unleached U/Fe solids indicate a relationship between the mol% U in the Fe oxide and the intensity or existence of the spectra features that can be assigned to UO₂²⁺ species (such as the IR asymmetric υ₃ stretch for O = U = O for uranyl). These spectral features were undetectable in carbonate- or oxalate-leached solids, suggesting solid phase and sorbed U(VI)O₂²⁺ species are extracted by the leach solutions. Uranium L₃-edge x-ray absorption spectroscopic (XAFS) analyses of the unleached U-Fe oxide solids with less than 1 mol% U reveal that U(VI) exists with four O atoms at radial distances of 2.19 and 2.36 Å and second shell Fe at a radial distance at 3.19 Å.Because of the large ionic radius of UO₂²⁺ (∼1.8 Å) relative to that of Fe³⁺ (0.65 Å), the UO₂²⁺ ion is unlikely to be incorporated in the place of Fe in Fe(III)-oxide structures. Solid-phase U(VI) can exist as the uranyl [U(VI)O₂²⁺] species with two axial U-O double bonds and four or more equatorial U-O bonds or as the uranate species (such as γ-UO₃) without axial U-O bonds. Our findings indicate U⁶⁺ (with ionic radii of 0.72 to 0.8 Å, depending on the coordination environment) is incorporated in the Fe oxides as uranate (without axial O atoms) until a point of saturation is reached. Beyond this excess in U concentration, precipitating U(VI) forms discrete crystalline uranyl phases that resemble the uranyl oxide hydrate schoepite [UO₂(OH)₂·2H₂O]. Molecular modeling studies reveal that U⁶⁺ species could bond with O atoms from distorted Fe octahedra in the hematite structure with an environment that is consistent with the results of the XAFS. The results provide compelling evidence of U incorporation within the hematite structure.     

Selective flotation of scheelite from calcium minerals with sodium oleate as a collector and phosphates as modifiers. II. The mechanism of the interaction between phosphate modifiers and minerals

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.     

Interaction of thionocarbamate and thiourea collectors with sulphide minerals: a flotation and adsorption study

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.     

氧化铁涂层石英砂滤料表面特征研究

采用高温加热法制备氧化铁涂层石英砂(IOCS),研究固化温度、改性剂浓度等因素对滤料表面性能的影响,通过磨损实验分析氧化铁涂层的耐磨稳定性.研究结果表明,IOCS表面氧化铁涂层的厚度大约为30～60 μm,固化温度影响涂层的形态和成分,进而影响IOCS表面电位,涂层处理过程要求改性剂浓度大于1.0 mol/L.在实际滤池反冲洗产生的磨损强度范围内,涂层磨损剥离量随磨损次数增加逐渐减小,涂层质量最终趋于稳定.     

Recycled concrete aggregate coated with quaternary ammonium compounds for water disinfection

Growing demand for point-of-use water treatment including greywater recycling as well as appropriate disinfection without formation of harmful disinfection byproducts (DBPs) calls for new methods of efficient microbial control. In recent years, antimicrobial nanomaterials (NMs) have been widely studied as a potential alternative to traditional chlorine disinfection, yet concerns over their releases to environments and subsequent impacts have limited their use on a large scale. In this work, recycled concrete aggregate (RCA) was proposed as a sustainable and environmentally friendly disinfecting substrate for water disinfection by coating with a composite of silica-quaternary ammonium compound (Fixed-Quat). Two different types (gel and particle) of Fixed-Quat were applied to RCA, and their adherence and antimicrobial activities were compared each other. When using E. Coli as a model bacterial pathogen, the Fixed-Quat gel and particle coated RCA materials showed similar and effective microbial inactivation performance with a rate of 2.0 × 10^?3 (gel) and 1.82 × 10^?3 (particle) log reduction cm^?2 min^?1. By potentially eliminating regulated DBPs formation and minimizing release of NMs into the environment, the antimicrobial coated RCA would be a promising and sustainable alternative to conventional disinfection methods in engineered aquatic systems.     

Mixed valence of iron in minerals with cation clusters

The valence and distribution of iron in vivianite, lazulite, babingtonite, rockbridgeite, acmite, aegirine-augite, hedenbergite, and ilvaite were studied with optical and Mössbauer spectroscopy. Optically activated intervalence charge transfer between Fe²⁺ and Fe³⁺ in neighboring sites through common edges or faces is observed in all these minerals irrespective of the polymerization of the iron-oxygen polyhedra ranging from finite clusters to infinite structural units. However, a distinct decrease occurs in the energy of the corresponding optical absorption band with increasing number of Fe²⁺ and Fe³⁺ ions involved in the charge transfer process. Thermally activated electron delocalization between Fe²⁺ and Fe³⁺ occurs only if Fe²⁺ and Fe³⁺ occupy crystallographically equivalent or geometrically very similar neighboring sites which share common edges to form extended structural units such as the ribbon in ilvaite. If the Fe-O polyhedra form finite clusters of two, three, or four polyhedra (e.g., in vivianite, lazulite, and babingtonite, respectively) no thermally-activated mixed-valence states of iron are observed. In aegirine, extended regions of the M1 chain are statistically occupied by Fe²⁺ and Fe³⁺ giving rise to thermally-activated electron delocalization in addition to the intervalence band in the optical absorption spectrum. The intensity of the optical intervalence absorption has been measured in a number of systems: ? values range from 60 to 210.     

矿山铁的硫化物矿物处理皮革厂含铬废水的研究

为了全面提升内蒙古大型硫铁矿的综合利用价值,尝试将其主要成分磁黄铁矿和黄铁矿分别用于处理含铬废水,找到了天然硫铁矿和改性硫铁矿处理Cr(Ⅵ)的最佳实验条件。与已有的研究相比,本研究所使用的矿样粒径减少到80~100目,用量减少了70%,所处理的含铬废水浓度增大到50 mg/m L。将处理含铬废水后的硫铁矿经XPS扫描分析后发现,天然黄铁矿在pH值分别为1.84、4.15和10.87的反应体系中处理Cr(Ⅵ)后,大部分的Cr(Ⅲ)以Cr2S3的物相出现,分别占总铬物相的77.99%、86.53和100%。天然磁黄铁矿在pH值为6.5,加热500℃改性后的黄铁矿在pH值为4.15时,也有相当量的三价铬以Cr2S3的物相出现。用已经获得的处理含铬Cr(Ⅵ)的最佳条件,直接用于处理某皮革厂高浓度的含Cr(Ⅲ)实际废水,去除率达73%。本研究为综合处理含铬废水提供了思路,成为矿山资源化的途径之一。     

The mechanism of cadmium surface complexation on iron oxyhydroxide minerals

Many sediment and soil systems have become significantly contaminated with cadmium, and earth scientists are now required to make increasingly accurate predictions of the risks that this contamination poses. This necessitates an improved understanding of the processes that control the mobility and bioavailability of cadmium in the environment. With this in mind, we have studied the composition and structure of aqueous cadmium sorption complexes on the iron oxyhydroxide minerals goethite (α-FeOOH), lepidocrocite (γ-FeOOH), akaganeite (β-FeOOH), and schwertmannite (Fe₈O₈(OH)₆SO₄) using extended X-ray adsorption fine structure spectroscopy. The results show that adsorption to all of the studied minerals occurs via inner sphere adsorption over a wide range of pH and cadmium concentrations. The bonding mechanism varies between minerals and appears to be governed by the availability of different types of adsorption site at the mineral surface. The geometry and relative stability of cadmium adsorption complexes on the goethite surface was predicted with ab initio quantum mechanical modelling. The modelling results, used in combination with the extended X-ray adsorption fine structure data, allow an unambiguous determination of the mechanism by which cadmium bonds to goethite.Cadmium adsorbs to goethite by the formation of bidentate surface complexes at corner sharing sites on the predominant (110) crystallographic surface. There is no evidence for significant cadmium adsorption to goethite at the supposedly more reactive edge sharing sites. This is probably because the edge sharing sites are only available on the (021) crystallographic surface, which comprises just ∼2% of the total mineral surface area. Conversely, cadmium adsorption on lepidocrocite occurs predominately by the formation of surface complexes at bi- and/or tridentate edge sharing sites. We explain the difference in extended X-ray adsorption fine structure results for cadmium adsorption on goethite and lepidocrocite by the greater availability of reactive edge sharing sites on lepidocrocite than on goethite. The structures of cadmium adsorption complexes on goethite and lepidocrocite appear to be unaffected by changes in pH and surface loading. There is no support for cadmium sorption to any of the studied minerals via the formation of an ordered precipitate, even at high pH and high cadmium concentration. Cadmium adsorption on akaganeite and schwertmannite also occurs via inner sphere bonding, but the mechanism(s) by which this occurs remains ambiguous.     

ESR dating of quaternary tephra from Mt. Osore-zan using Al and Ti centres in quartz

Quaternary tephra of Mt. Osore-zan was dated by electron spin resonance. Quartz grains were separated from the tephra and ESR signals of Al and Ti centres were measured at 77 K. The signals of Al and Ti centres which have a complicated hyperfine structure were simplified by using wider field modulations width (5 gauss) than usually used (0.5–1 gauss). The influence of 5 gauss modulation width on the measurement of the signal intensity of Al and Ti centres was investigated. The intensity of the signal increases linearly with gamma irradiation and total doses obtained were 178 to 273 Gy and ESR ages were 0.19 to 0.32 Ma. These ages agree with the estimated age of about 0.3 Ma from the correlation of volcanic ash and terrace level.     

Formation of iron minerals on zeolite matrix

We present results of a two-year research experiment on the processes involving iron-manganese bacteria at different biogeochemical barriers. Analysis of experimental samples was carried out on a scanning electron microscope (EVO-40HV, Carl Zeiss) and an X-ray diffractometer (Rigaku MiniFlexll). It is shown that goethite can form in vitro in the presence of iron-containing groundwater and iron-manganese bacteria.     

X-ray spectra of iron atoms in minerals

The results of X-ray fluorescence Ka _1,2 and Kβ₁,β′-spectra of iron in 54 samples, including 23 minerals, are presented. Spectrum characteristics are mainly dependent on the environment of iron in the sample, the most susceptible parameter being the chemical shift δβ₁. For the compounds investigated δβ₁ varies between ?1.58 eV and +1.56 eV when referring to metallic iron. Chemical shifts of compounds with predominantly covalent bonds exhibit more negative values, compounds with metallic bonds nearly vanishing values and compounds with predominantly ionic bonds more positive values. The FeKβ₁,β′-group of lines is actually a superposition of three lines: the long-wave line β′ and two overlapping lines β ₁ ⁵ and β ₁ ⁷ of which the superposition is conventionally denoted as β₁. The relative intensity of β ₁ ⁵ increases with ionicity of the bond, while that of β ₁ ⁷ decreases. The effective charge of iron has been determined for a group of iron-bearing minerals.     

Distribution of ammonium in minerals of metamorphic and granitic rocks

Sixty-nine analyses are given for NH₄ in minerals of metamorphic and granitic rocks mostly from the Ryoke belt, Japan. The distribution of NH₄ in coexisting minerals is quite systematic, suggesting that NH₄ is one of the stable geochemical components in high temperature processes.Biotite has the highest content of NH₄, followed by muscovite, K-feldspar and plagioclase. Pure quartz is almost free from NH₄. Calcic plagioclase contains less NH₄ than does sodic plagioclase. The partition coefficients $\text{D}{}^{\mathrm{<mtext>Pl</mtext><mtext>Bi</mtext>}}$, $\text{D}{}^{\mathrm{<mtext>Kf</mtext><mtext>Bi</mtext>}}$ and $\text{D}{}^{\mathrm{<mtext>Kf</mtext><mtext>Bi</mtext>}}$ are, on the average, 0.11, 0.38 and 0.43 respectively. The fractionation of NH₄ in these minerals is quite similar to that of Rb but much smaller than that of Cs.Distribution of NH₄ as well as those of Rb and Cs appears to be explained by its ionic radius and the shortest cation-O distances in alkali positions of minerals.     

Gas-chromatographic investigations on dimethyldioctadecyl ammonium derivatives of different clay minerals

The gas-chromatographic behaviour (selectivity performance for cyclohexanebenzene and m-, p-xylenes pairs separation) of dimethyldioctadecylammonium complexes with kaolinite, fire-clay, halloysite, attapulgite, hectorite and various montmorillonites, nontronites and vermiculites has been investigated. The obtained data indicate the influence of specific surface and charge density on relative retention value (), and of substitution location (tetrahedral versus octahedral sheet) within the clay lattice on selectivity. Hence, derivatives with nontronites and vermiculites, that is the clay minerals where the principal lattice substitutions are predominantly occurring within the tetrahedral sheet and possessing the highest surface charge density, are very effective sorbents for gas-chromatographic use. The application of gas-chromatography as investigation tool of clays surface is suggested.