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.     

X射线光电光谱表征金属氧化物的酸碱性

本文探讨了氧配位的八面体及四面体的金属配合物中氧原子的价态变化及其酸碱性差异之间的关系。首先利用X射线光电光谱（XPS）分别推导出了氧原子在碱及碱土铝酸盐、铬酸盐、高铁酸盐、钼酸盐及钨酸盐中的价态,随后对氧原子的价态及氧化物的酸碱性质进行了比较。研究结果表明,氧原子的价态在这两种配位构型的化合物中没有显著的差别,其酸碱性的不同在于四面体配位的金属化合物中O2p态在非成键和成键的电子密度中高价带的分裂。     

彩色电气石致色离子的化学状态研究

为探究不同颜色电气石中致色元素的化学状态及其化学环境,利用X射线光电子能谱方法对绿色调（墨绿色、蓝绿色、淡绿色）和粉红色调电气石样品进行分析。结果表明,绿色调和粉红色调电气石样品中均含有少量的过渡金属离子,如Fe,Mn,Ti,Cr,且不含Li和Be。不同颜色的电气石晶体中过渡金属阳离子的化学状态相同,且分别为Fe3＋,Mn4＋,Ti4＋,Cr3＋,但其与阴离子配位的环境有所差别。绿色调电气石样品中虽然Fe的质量分数有较大的差别,但均有部分Fe元素与F结合,即占据晶体结构中的Y位;粉红色电气石样品中,Fe离子没有与F形成配位,仅占据结构中的Z位。相反,在粉红色电气石样品中,Mn主要与F结合配位的方式存在,占据结构中的Y位,而绿色调电气石样品中大部分的Mn与O配位成键,只有少部分的Mn与F结合配位。由于Fe3＋,Mn4＋离子对之间电荷转移的可能性不大,故电气石的颜色可能主要由于d—d电子跃迁和氧与金属离子（O2--M）间电荷转移吸收引起,尤其是由于化学环境的差异（包括配位阴离子种类、杂质缺陷、结构畸变等）所引起。     

辉石相变的矿物物理特征及滑石瓷老化机理的探讨

本文采用X射线衍射物相定量分析,透射电子显微镜及X射线电子能谱分析研究了原顽辉石→斜顽辉石的相变特征,提出了滑石瓷老化的实质是当原顽辉石Pbcn相向斜顽辉石P2_1/c相转变时,由于体积缩小和钡玻璃相拉应力的减少,导致滑石瓷表面产生微裂缝,从而加剧老化的过程。     

Effect of surface oxide/hydroxide products on the collectorless flotation of copper-activated sphalerite

The change in collectorless flotation of sphalerite with pH and Cu(II) concentration was correlated with the type and proportion of species present on the sphalerite surface. The solution and surface species were determined using a combination of analytical techniques including zeta potential measurement and X-ray photoelectron spectroscopy. An optimum copper concentration for maximum sphalerite flotation was identified, beyond which flotation decreased. This decrease in flotation coincided with the precipitation of copper hydroxide in neutral to mildly alkaline pH conditions. The hydrophobic polysulfide and hydrophilic copper hydroxide species were the main surface species influencing sphalerite flotation.     

腐植酸改性强化磁铁矿吸附水体中铅镉的实验研究

磁铁矿是一种绿色廉价的矿物材料,对水体中重金属离子具有良好的吸附性,但吸附容量低,选择性差,易团聚,通过改性可以克服该缺点并提高其吸附性能。本文以腐植酸为改性剂,采用常温水相反应制备了腐植酸改性磁铁矿吸附材料。通过傅里叶红外光谱(FTIR)、扫描电镜(SEM)和X射线光电子能谱(XPS)表征研究其表面形貌和微观结构。采用静态平衡实验考察了pH、吸附时间等因素对铅、镉吸附性能的影响,探讨了吸附动力学规律,拟合了吸附等温线。结果表明:腐植酸上的羧基、羟基被成功地接枝到了磁铁矿表面。在室温下,溶液初始pH对Pb~(2+)的吸附率几乎无影响,对Cd~(2+)的影响较大,当pH=7时,Pb~(2+)和Cd~(2+)吸附率均达到了95%。对初始质量浓度为10mg/L的Pb~(2+)、Cd~(2+)最佳吸附平衡时间为360min,吸附过程符合准二级动力学方程。吸附等温线实验得到的竞争吸附顺序为Pb~(2+)Cd~(2+),由Langmuir等温吸附模型得到Pb~(2+)、Cd~(2+)饱和吸附容量分别为39.27mg/g、28.95mg/g,显著大于磁铁矿的饱和吸附容量,表明磁铁矿经腐植酸改性后增强了对水中铅镉的吸附能力。     

常见硫化物表面的XPS研究

采用XPS分析方法,研究了黄铁矿、磁黄铁矿、方铅矿、黄铜矿、闪锌矿和毒砂等常见硫化物矿物表面的化学成分及其化学态,从而探讨硫化物表面的氧化和次生变化。研究发现：（1）硫化物矿物表面在氧逸度较高的情况下很容易发生变化,其氧化产物很复杂,主要是其金属元素的高价态氧化物、氢氧化物和硫酸盐等;（2）就一般常见硫化物而言,相对比较稳定的是黄铁矿;（3）常见硫化物经氧化后,其表面的原子比率常常显示硫富余;（4）在含铁的各种常见硫化物中,除黄铁矿表面的铁相对稳定外,毒砂表面的铁也相对较稳定,而闪锌矿表面的类质同像铁却容易被氧化而发生变化。     

X-ray photoelectron study of oxygen bonding in crystalline C–S–H phases

We recorded the photoelectron spectra of various crystalline calcium silicate hydrates (C–S–Hs) and have examined their O 1 s photoelectron spectra. The spectra are asymmetric, with contributions assigned primarily to bridging and non-bridging oxygen species. There is an increased contribution due to the presence of non-bonding oxygen atoms with increasing calcium:silicon ratio. Additionally, there are slight changes in theO 1s-binding energies with changes in calcium:silicon ratio. These changes are explained in terms of bonding and silicate structure.     

邯郸-峰峰矿区不同变质程度煤中有机氮的赋存形态

氮是煤中的常见元素之一,煤中氮的赋存形态多样且随煤阶发生变化。以邯郸-峰峰矿区为例,利用X射线光电子能谱（XPS）实验,研究不同变质程度煤（R_ran=1.08%~3.67%）中有机氮的赋存形态,探讨煤中各形态有机氮相对含量随煤阶的变化规律。结果表明：按N 1s XPS谱图分峰峰值的结合能可将煤中氮的形态归为N-6、N-5、N-Q和N-X四种;研究区煤中N-5的相对含量最高,且随着煤阶的增高而降低;N-Q的相对含量随着煤阶的增高而增高;煤中N-6的相对含量随煤阶呈“增-减-稳”的变化规律;N-X的相对含量为9.1%~35.1%,其与煤阶关系不明显;在煤阶R_ran=1.08%~1.47%的范围内,煤的N 1s XPS谱图中缺失N-Q分峰,表明褐煤中相对含量最高的质子化吡啶氮在此阶段已几乎全部去质子化而转化为吡啶氮。不同变质阶段氮的赋存形态变化特征对燃煤发电及煤化工领域煤化学参数选取提供参考。     

羧基功能化共价膦腈聚合物用于酸性水体中钪的选择性分离

发展高效选择性分离技术实现酸性介质中稀土元素钪（Sc）的高效提取,有利于满足工业生产过程对Sc日益增长的需求。吸附法可以有效地简化Sc的提取流程,降低生产成本。然而,现有吸附材料如硅基材料、生物质材料、金属有机骨架材料等在分离酸性介质中的Sc时仍存在效率低、选择性差等缺点,从而限制了其实际应用。因此,针对处理含Sc尾矿等原料时往往需要进行酸处理的实际情况,制备具备更强结合能力的吸附剂,实现酸性介质中Sc（III）的高效选择性分离至关重要。本文分别以间苯三酚和2,4,6-三羟基苯甲酸为构筑单元,与六氯三聚膦腈共价交联制备了共价膦腈聚合物（covalent phosphonitrile frameworks,CPF-T）和羧基功能化CPF材料（CPF-T-COOH）。采用扫描电镜、红外光谱、热重、氮气吸附-解吸等分析技术对材料的结构进行表征,并探索了它们作为Sc（III）吸附剂的应用潜力。吸附实验结果表明,在溶液pH=2时,CPF-T和CPF—COOH对Sc（III）的吸附平衡时间分别为120min和30min,最大吸附容量分别为22.48mg/g和64.63mg/g,在混合离子溶液中的分配系数分别为5.1×102mL/g和4.0×103mL/g。值得注意的是,在酸性介质（pH=1～3）中,CPF-T-COOH对Sc（III）的吸附率仍维持在95%以上,明显优于CPF-T（低于60%）以及大多数已报道的吸附材料。采用X射线光电子能谱对作用机理进一步分析,结果显示除了CPF-T骨架中N/O原子与Sc（III）的配位作用外,骨架—COOH上的O原子与-OH基团分别提供了额外的配位作用与离子交换作用,有效地增强了CPF—COOH对Sc（III）的吸附亲和力。该研究表明,利用多种功能基团的协同作用是提高吸附剂吸附性能的有效策略之一,所制备的CPF-T-COOH材料性能优异,展现了其作为Sc（III）吸附材料的良好应用前景。     

Surface chemical analysis in coal preparation research: complementary information from XPS and ToF-SIMS

The application of X-ray photoelectron spectroscopy (XPS) to coal surface characterisation for preparation research is described. Progress towards the acquisition of complementary surface chemical information by time-of-flight secondary ion mass spectrometry (ToF-SIMS) is also discussed. Surface-based beneficiation techniques such as flotation are assuming greater importance as the proportion of fines in raw coal increases due to the proliferation of high capacity mining methods. A necessary condition for the floatability of a coal particle is adequate hydrophobicity, and the degree of hydrophobicity of the flotation concentrate is one factor influencing the ease with which its dewatering can be affected. The hydrophobicity of a coal is very difficult to measure directly because of microporosity, and it is often necessary to deduce the degree of hydrophobicity from a knowledge of the surface chemistry. XPS is able to provide sufficient analytical data to allow relative levels of hydrophobicity to be estimated. In principle, ToF-SIMS should be able to supply additional information enabling refinement of such estimates; however, there are insufficient data at present to allow the ionic fragments detected to be related to specific functional groups at the coal surface.     

五颜六色的黄龙玉及致色机理

黄龙玉是微晶质石英集合体。扫描电镜对黄龙玉石英晶间黏土矿物形成分析和能谱组分分析,表明石英晶间主要是胶状褐铁矿和泥质伊利石,黄龙玉石英微晶间充填物的种类、含量决定黄龙玉颜色。褐色胶状褐铁矿使玉石多呈红色调,黄色胶状褐铁矿物与伊利石混合物使黄龙玉呈浅橙色或黄色,黑色泥质伊利石黏土矿物使玉石带青、灰、黑等色调。黄龙玉中常见的"金砂"是玉石中含有自形黄铁矿而成,如果黄铁矿细小并沿层理分布,也会使黄龙玉呈现黑色。沿黄龙玉裂缝面树枝状分布的氧化锰构成了黄龙玉中的"水草"。充填物的含量一方面决定黄龙玉色的深浅,另一方面还影响着黄龙玉的透明度。充填物含量高,黄龙玉色深,透明度差;充填物含量低,黄龙玉色浅,透明度好;不含充填物就形成了透明的白色黄龙玉。     

Evaluation of Experimental Procedures and Discussion of Two Different Modelling Approaches with Respect to Long-term Kinetics of Metal Cation Sorption onto (Hydr)oxide Surfaces

Experimental procedures as well as literature data and modelling of long-term kinetics of metal ion adsorption processes onto thermodynamically stable (hydr)oxide surfaces from aqueous solution are evaluated. It is concluded that when experimental uptake data are obtained by the solution depletion method precise information on experimental procedures is crucial. This is true both for preliminary kinetics studies (which intend to fix an equilibration time used for subsequent thermodynamic studies) and for true kinetic studies. For the usually given adsorption versus time curves the corresponding (possibly changing) values of pH should be added. The use of sorption pH edges measured at different times to obtain kinetics curves at constant pH may not correspond to the actual behaviour of the system but be rather an artificial construct.Concerning the models two basically different mechanisms have been used to account for the slow sorption step, which occurs in long-term studies: intraparticle diffusion of the adsorbing metal cation and slow redistribution of surface species. It is shown that the two mechanisms cannot be distinguished using macroscopic uptake data alone: data, which have been interpreted using one approach, may equally well be interpreted using the other one.     

HPHT合成钻石在首饰中的鉴别特征

国家黄金钻石制品质量监督检验中心收到待检的百余件群镶钻石首饰中发现混有大量HPHT合成黄色钻石.采用宝石显微镜、红外光谱仪、X射线荧光光谱仪、紫外可见光分光光谱仪、紫外荧光灯、DiamondView^TM等对HPHT合成钻石样品做了详细地测试与分析.结果表明,这些HPHT合成钻石样品具有较为统一的黄色,放大检查可见合成钻石内部含有大量棒状、柱状、细小微粒状的铁镍合金包裹体,且几乎都有磁性,有些磁性甚至较强;样品的红外反射光谱非常特征,均具有明显的1 131 cm^-1处的吸收峰,为Ⅰb型钻石,而Ⅰb型钻石在天然钻石中极少见到;X射线荧光光谱测试显示有强烈的铁峰和镍峰,且在短波紫外线下多数具有绿黄色荧光.HPHT合成钻石在DiamondView^TM下具有不同程度的黄绿色荧光,部分具有黑十字现象.     

薄膜吸附制样-波长色散X射线荧光光谱法测定卤水中的溴

溴主要以离子形式分布在地壳水圈的溴化物型卤水、卤化物硫酸盐型卤水中,目前应用波长色散X射线荧光光谱(WDXRF)测定卤水中的溴,主要采用粉末载体压片法前处理待检样品,制样工作量大,制样均匀性和制样过程中的污染都会影响准确度,方法实用性不强。本文借助薄膜吸附前处理卤水样品,通过优化筛选薄膜材料及卤水取样量,确定移取50μL卤水样品滴于Ф=40 mm的3#层析滤纸的圆心位置,自然晾干后高压压平来前处理待检样品,采用人工配制标准样品校正溴的标准曲线,用WDXRF测定溴的含量。钾钠钙镁氯和硫酸根等共存离子的影响可以忽略,方法检出限(3σ)为0.95 mg/L,精密度(RSD,n=11)不大于0.8%,加标回收率为99.4%~101.2%。本方法操作简便,不需要使用化学试剂,解决了现行卤水中溴的分析方法流程复杂、分析成本高的问题。     

The adsorption of polysaccharides onto mineral surfaces: an acid/base interaction

Natural polysaccharides such as starch, dextrin, guar gum, cellulose and their derivatives are promising non-toxic organic depressants. Although generally perceived as non-selective, these polymers have found use in commercial processes or have been tested in laboratories in practically all flotation systems involving every type of minerals. In this communication, the adsorption mechanisms of natural polysaccharides are reviewed, with the objective of promoting the wider applications of the polymers. While it seems generally accepted that natural polysaccharides interact with minerals via surface metal-hydroxylated species, an acid/base interaction model between the natural polysaccharides and mineral surfaces is proposed to explain many observed adsorption and flotation phenomena.     

Intercalation of kaolinite with acetamide

Upon intercalation of both ordered (low defect) and disordered (high defect) kaolinites with acetamide, two types of interaction are observed. Firstly, hydrogen bonding between the NH₂ groups of the acetamide with the siloxane oxygens is formed, as evidenced by the formation of two new bands at 3400 and 3509 cm^–1. Secondly, the appearance of additional bands at ∼3600 cm^–1 in both the infrared and Raman spectra of the acetamide intercalates is attributed to a second type of hydrogen bonding by the interaction of the C=O group and the inner surface hydroxyls. Changes in the intensity of the hydroxyl deformation modes in the 895 to 940 cm^–1 region are attributed to the changes in the hydrogen bonding of the kaolinite surfaces. It is proposed that the hydrogen bonding between the adjacent kaolinite layers is replaced with hydrogen bonding between both kaolinite surfaces and the acetamide molecule. Changes in the molecular structure of acetamide are observed upon intercalation. The amide 1 band is lost and replaced with a well-defined NH₂ deformation vibration. The loss of the amide 1 band is attributed the hydrogen bond formation between the amide hydrogens and the siloxane surface. The bands of the C=O group at 1680 and 1740 cm^–1 become a single band at 1680 cm^–1. The amide 2 band remains unchanged. The lack of intensity of the 1740 cm^–1 band is attributed to the formation of hydrogen bonding between the inner surface hydroxyl groups and the carbonyl group. Received: 4 February 1998/ Revised, accepted: 30 June 1998     

Observation of the oxidation of galena using Raman spectroscopy

Oxidation of galena (PbS) to oxysulfates, (PbO·PbSO₄, 3PbO·PbSO₄ and 4PbO·PbSO₄)_, has been observed using Raman spectroscopy. Peaks associated with the oxidation products have been assigned. The reaction appears to be a high temperature oxidation induced by the high laser (25 mW at 514.5 nm) power density at freshly cleaved galena surfaces. Damage to the galena surface was observed visually under the microscope. Moderate laser powers (5 mW at 514.5 nm) did not result in any damage. No Raman bands were observed or expected for freshly cleaved galena because it has the rock salt structure. Laser-induced production of these oxysulfates is dramatically different from high temperature methods previously employed. This procedure will permit easy identification of galena in complex mineral ore samples. Spontaneous air oxidation of freshly cleaved galena to oxides or polysulfides was not detected.     

锐钛矿光电子强化黑曲霉吸附铅离子实验研究

铅元素在自然界分布广泛,其可溶性盐对动植物及人体有巨大毒性,借助真菌等生物修复技术手段清除环境中铅污染逐渐成为研究热点之一。本文使用溶胶凝胶法合成了锐钛矿电极,通过X射线衍射(XRD)、拉曼测试、环境扫描电镜和电化学测试等对其进行了系统表征,进而联合实验室分离筛选出的一株黑曲霉Aspergillus niger Bpb1成功构建了光-半导体矿物-微生物系统。研究了光电子对黑曲霉吸附铅离子的影响,实验结果表明锐钛矿光电子与黑曲霉协同作用下,实验组较对照组铅离子吸附速率平均增加33.6%,最高增加42%。进一步使用环境扫描电镜观察黑曲霉外部形态,发现光电子不影响铅矿物的形态。结合能谱测试和前人文献得知铅离子与有机酸结合形成以有机铅盐为主的矿物,缠绕在菌丝中。本研究实现了利用光能加速真菌代谢的过程,表明锐钛矿光电子与黑曲霉协同作用只对真菌吸附铅离子速率产生一定的加强,并未影响其成矿形态。     

Adsorption of NO, SO2 and light hydrocarbons on activated Greek brown coals

Twenty-eight samples of peat, peaty lignites and lignites (of both matrix and xylite-rich lithotypes) and subbituminous coals have been physically activated by pyrolysis. The results show that the surface area of the activated coal samples increases substantially and the higher the carbon content of the samples the higher the surface area.The adsorption capacity of the activated coals for NO, SO₂, C₃H₆ and a mixture of light hydrocarbons (CH₄, C₂H₆, C₃H₈ and C₄H₁₀) at various temperatures was measured on selected samples. The result shows a positive correlation between the surface area and the gas adsorption. In contrast, the gas adsorption is inversely correlated with the temperature. The maximum recorded adsorption values are: NO = 8.22 × 10^− 5 mol/g at 35 °C; SO₂ = 38.65 × 10^− 5 mol/g at 60 °C; C₃H₆ = 38.9 × 10^− 5 mol/g at 35 °C; and light hydrocarbons = 19.24 × 10^− 5 mol/g at 35 °C. Adsorption of C₃H₆ cannot be correlated with either NO or SO₂. However, there is a significant positive correlation between NO and SO₂ adsorptions. The long chain hydrocarbons are preferentially adsorbed on activated lignites as compared to the short chain hydrocarbons.The results also suggest a positive correlation between surface area and the content of telohuminite maceral sub-group above the level of 45%.