Effect of contact angle,surface tension and zeta potential on oil agglomeration of celestite

The influences of contact angle, surface tension and zeta potential on oil agglomeration recovery of celestite mineral have been investigated in the present work. Therefore, celestite mineral in methanol–water suspension was agglomerated by the use of oil (kerosene) in the presence of sodium oleate as a surfactant. The zeta potential values of celestite surfaces were measured depending on pH and sodium oleate concentration. The zeta potential values of celestite surfaces became negative even more owing to the sodium oleate adsorption. However, this phenomenon did not affect the oil agglomeration recovery at all. It was found that both increasing contact angle and surface tension raised the oil agglomeration recovery of celestite mineral. Eventually, the agglomeration degree of celestite mineral in the suspension was not lower than a particular surface tension value corresponding to the critical solution surface tension for oil agglomeration (γ_c-a). The γ_c-a values were slightly greater than the critical surface tension of wetting (γ_c) values.     

Surface morphologies and floatability of sand-blasted quartz particles

Significance of morphological properties of minerals in flotation has been recognized for several decades but sufficient research efforts have not been devoted to this problem. In this study, a special design laboratory scale blasting equipment was used to produce quartz particles with different shapes and roughness values, and develop a new method by which flotation characteristics of quartz particles could be enhanced. For this purpose, micro-flotation experiments were carried out with un-blasted and blasted quartz particles, and the results were correlated with their shape and roughness values analyzed with SEM, BET, and Image analysis methods. The results indicated that the blasted quartz particles with more angular and rougher surfaces gave better floatability compared to the un-blasted quartz particles.     

石英的矿床工业类型与应用特点

石英的工业应用十分广泛,使用量和工业产值巨大,尤其是在电子信息、新材料和新能源等战略性新兴产业中得到广泛应用,并由于石英是硅产业的物质基础和芯片生产所需关键材料的原料,因此石英是一种战略性非金属矿产。本工作根据石英SiO₂纯度及其工业应用特点,将石英及相关产品划分为w（SiO₂）99%±、w（SiO₂）99%~99.9%、w（SiO₂）>99.9%等三大类。其中,SiO₂纯度≥99.998%（4N8）的高纯石英高端产品是一种矿物功能材料和关键基础材料,目前还需要从国外高价进口;石英在自然界中的分布广泛,成因多种多样,但目前能够作为工业应用的石英矿物资源主要有天然水晶、石英砂岩、石英岩、脉石英、粉石英、天然石英砂和花岗岩石英等7种矿床工业类型;我国石英矿物资源丰富,矿产地遍布全国,但迄今为止尚未发现能够稳定满足工业生产需要的高纯石英优质原料矿产资源;石英的矿床工业类型与工业应用存在密切的关系,如何根据不同矿床工业类型石英的特点有针对性地开发利用,已成为石英原料加工技术及其项目成败的关键点。      

Flocculation and flotation response of Rhodococcus erythropolis to pure minerals in hematite ores

Rhodococcus erythropolis as a flotation collector for hematite was evaluated in the study. The surface morphology and cell wall composition of R. erythropolis was analyzed. Zeta potentials for four pure minerals from hematite ores were measured before and after adsorption by R. erythropolis. Pure mineral flotation tests and mixed mineral separation tests were performed to describe adsorption characteristics and mechanisms. A rod-shaped bacterium was detected with CH₂, CH₃ and COO groups on its cell wall that imparted hydrophobicity and negative charges. The ability of R. erythropolis to collect hematite was stronger than its ability to collect quartz, kaolinite and apatite. For a pulp pH of 6 and a cell concentration of 75 mg/L, recovery rate of hematite was 89.67%. The recovery differences between hematite and quartz, kaolinite and apatite were 66.43%, 60.36% and 54.30%, respectively. These data indicated that electrical properties of hematite surface were more suitable for adsorption of R. erythropolis than other three minerals. The adsorbed hematite particles appeared as large agglomerates after interaction with R. erythropolis. The quartz, kaolinite and apatite particles, however, were in the form of dispersed particles or small agglomerates. The chemical adsorption of hematite on bacterial cell wall resulted in agglomeration. The effects of flocculation and flotation of R. erythropolis on micro-fine hematite particles were characterized for the first time. The results showed that R. erythropolis can act as a flotation collector for hematite from hematite ores.     

马达加斯加某三水铝土矿磨矿浮选脱硅工艺试验研究

铝土矿试验矿样来自马达加斯加Sofia地区,Al₂O₃含量为32.06%,SiO₂含量为34.06%。矿石中含铝矿物主要为三水铝石;含硅矿物主要为石英,其次为高岭石。三水铝石以微晶聚合体形式存在,微细粒的其他矿物以包体形式嵌布在其中,矿样粒级越细聚合体中杂质矿物含量越高。矿样中-0.028 mm粒级产率约占30%,高杂质含量的三水铝石聚合体占比超过95%,反浮选或正浮选几乎没有脱硅效果。石英的嵌布粒度集中于0.1～0.8 mm,原矿矿样常规破碎磨矿产品中SiO₂在0.074 mm以上粗粒级富集,富含石英矿物的矿粒过粗,采用反浮选无法脱除。研究提出了便于工业化实施的脱泥、分级、分别磨矿合并反浮选工艺流程,未破碎原矿矿样用2 mm的筛子筛分,+2 mm粒级矿样单独破碎磨矿,-2 mm粒级矿样脱泥、沉砂单独磨矿,两种磨矿产品合并进入反浮选脱硅,获得铝硅比大于10、Al₂O₃回收率大于40%的精矿。     

高纯石英砂资源及加工技术分析

高纯石英砂是微电子、光纤通信、航空航天等高新技术产业的基础原材料,战略地位非常重要。目前,制备高纯石英砂主要通过化学合成、天然水晶加工及石英矿物深度提纯。其中,通过化学合成和天然水晶加工的制备方法受原料、成本、产量等方面的制约,难以大规模工业应用;因此,通过石英矿物制备高纯石英砂的加工技术将是未来的主要研究方向。然而,我国对以石英矿物为原料制备高纯石英砂的相关研究起步晚、研究少,技术被欧美发达国家长期垄断,市场大量依靠进口。从原料分析出发,对比了用于制备高纯石英砂的石英原矿的矿物特性,得出花岗伟晶岩和脉石英是制备高纯石英砂的最理想原料。系统分析了石英原矿中的伴生脉石矿物类型以及Al、Fe、Ca、K等常见杂质元素的存在形式和附存状态,并着重分析了晶格杂质和包裹体杂质的晶体构型,指出了晶格杂质难以脱除是制约高纯石英砂品质的主要原因。从矿物加工专业角度,并依据不同的加工目的将现行的高纯石英砂加工技术分成4个大类,对各类生产工艺状况进行了详细的分析概括,指出了现行工艺技术的不足以及与国际先进技术水平间的差距。在此基础上提出,目前高纯石英砂生产和研究中存在的问题及未来的研究方向,为今后相关研究提供理论指导。     

New experimental evaluation techniques for selectivity of collecting agents for gold and platinum flotation from fine-impregnated noble metal ores

It is proposed to apply nanosize Au and Pt particles to ground mineral particles for the analysis of flotation and adsorptive properties of new reagents. The authors have obtained specimens of pyrite, arsenopyrite and quartz artificially enriched by nanosize gold particles. Reductive adsorption from Na₂[PtCl₆] and Na[AuCl₄] produced pyrrhotine uniformly applied with microsize platinum particles. The article discusses the application range of the proposed techniques and methods of examination of specimens and interaction between reagents and micro- and nanosize gold and platinum particles depending on the conditions of sulfide treatment by the noble metals and on properties of a host mineral. Advanced integrated analysis of interaction between the nitrogen-bearing reagent MTKh and gold confirmed chemically induced selectivity of MTKh towards gold     

Comparison of different 2D image analysis measurement techniques for the shape of talc particles produced by different media milling

Talc, which is an extremely versatile industrial mineral, has found increasing number of uses in various industries such as paint, paper, plastic, ceramic and cosmetic. As it is well known, the particle shape is one of the main properties affecting the behavior and properties of mineral particles, especially for the bubble-particle attachment in flotation.In this study, shape characteristics of talc particles produced by laboratory ball and rod mills were determined by automated image analysis using Malvern Morphologi® G3 instrument. The results were compared by previous studies on the same samples that used other shape characterization techniques namely Scanning Electron Microscope (SEM) ( [Yekeler et al., 2004] and [Hi?y?lmaz et al., 2004]) and Clemex image analysis system (Ulusoy, 2008). About 10,058 particles for ball milled product and 7086 particles for rod milled product were measured for the shape analysis by the Malvern Morphologi® G3 instrument. They were expressed in terms of Aspect ratio, HS Circularity and Elongation and compared by applying t-test using the software Statistical Package for Social Science (SPSS) with a 0.05 significance level. t-Test revealed that, the difference between the image data group for different mill products are significant with a 95% confidence level.Although lower sample population was used for the SEM and Clemex analysis techniques than for the new technique Malvern Morphologi® G3, there is a clear difference in the particle shape obtained by different grinding methods for the talc mineral used. The determined shape property depends on the measurement technique applied. However, the results are in good agreement with each other by this study. i.e., more elongated talc particles were obtained by rod mill product.     

石英玻璃矿物原料的特征与制备

综述了石英玻璃天然原料的质量、加工工艺及矿物特征。从加工技术和石英矿物特征两方面分析了降低原料中杂质和气体含量的途径，并提出，包裹体和晶格离子等矿物特征是决定石英原料应用及质量的重要因素。     

A t10-based method for evaluation of ore pre-weakening and energy reduction

Currently the effect of the pre-weakening of ore particles by high voltage pulses is evaluated by the percentage change of A 1 b values between pulse-treated and untreated ore particles. The values of A 1 b, widely used as an ore breakage competence indicator in the mineral industry, are determined from the parameters of the JKMRC breakage models. In this study a t₁₀-based method was developed to predict the degree of size reduction, t₁₀, of pulse-treated particles from that of untreated particles broken at the same size/energy level. This method incorporates one parameter, C_Ab, which is equivalent to the percentage change of A 1 b values.The t₁₀-based method was validated using nine sets of comparative JK Rotary Breakage Tester data on pulse-treated and untreated ore samples over a wide range of impact specific energies and particle sizes. The t₁₀-based method can be used to calculate the energy reduction due to the pre-weakening effect in the downstream comminution process. It indicates that the energy reduction by pre-weakening increases with an increase in the target product fineness and the degree of pre-weakening, and with the decrease in feed particle size.     

高纯石英原料矿物学特征与加工技术进展

以天然石英矿物为原料是获取广泛应用于高科技领域重要非金属矿物材料高纯石英的主要途径。天然石英矿物中杂质元素赋存状态是选择正确高纯石英原料和制定最佳石英提纯方案的重要参考,通过分析不同杂质可选性,得出矿物包裹体、流体包裹体和晶格杂质含量决定了石英矿提纯加工后最终质量。高纯石英加工过程就是尽可能完全分离出天然石英矿物中各种杂质。通过分析石英中共伴生独立矿物分选、包裹体杂质分离和晶格杂质脱除加工高纯石英技术,认为物理分选过程中分离独立矿物杂质、连生体矿物杂质和包裹体杂质,是今后高纯石英加工中必须重视的问题;同时指出流体包裹体爆裂、氯化脱气和晶格杂质脱除技术与机理有待进行更加深入研究。在此基础上提出了关于我国高纯石英的发展建议。      

An acoustic emission study of damage development and stress-memory effects in sandstone

As part of a study of damage development and stress-memory effects, we have carried out a series of laboratory acoustic emission (AE) experiments on dry Darley Dale sandstone under triaxial compressive loads. In particular, we studied the shape of damage surfaces in stress space. Like the yield surface in the theory of plasticity, a damage surface is defined as the locus of points in 3D stress space beyond which additional permanent damage develops. The shape of a damage surface thus provides a means of characterising the state of damage corresponding to the state of stress to which the material has previously been subjected.In our experiments, which were limited to the cross-section of stress space where σ₂ = σ₃ = P_c (P_c being the confining pressure), the points of the damage surface were indicated by the onset of AE. The damage surface in (P_c, σ₁)-space corresponding to an initial stress state (P_cⁱ, σ₁ⁱ) is almost linear in the region where P_c > P_cⁱ. In the region where P_c < P_cⁱ the gradient of the damage surface becomes clearly larger. We compare the experimental results with predictions based on a 2D model of secondary microcrack (wing-crack) formation from frictional surfaces. According to this model, the damage surface is predicted to consist of two linear parts connected by a vertex (or “knee”) located at the point (P_cⁱ, σ₁ⁱ). The comparison shows that the model, although relatively simple, explains many features of the experimentally observed damage surfaces. The results also have implications in terms of a stress-memory effect. If the initially applied stress state (P_cⁱ, σ₁ⁱ) is not known, then it might in principle be derived from the position of the vertex in an experimentally measured damaged surface.     

滤纸模板法制备Ag-SnO_2电接触材料

首先以纳米SnO_2粉体和Ag NO3为原料,滤纸为模板,通过浸渍、煅烧制备了Ag-SnO_2复合粉体,然后利用Ag-SnO_2粉体为原料,采用压制、烧结工艺制备了Ag-SnO_2电接触合金。进一步通过XRD和SEM等分析手段对所制备的复合粉体和合金样品进行表征,并借助TG-DSC对滤纸前躯体的分解过程进行分析,同时研究了不同纳米SnO_2含量对Ag-SnO_2电接触合金组织和性能的影响。结果表明,所制备的Ag-SnO_2复合粉体由四方相金红石型结构的SnO_2和立方相的银组成,模板去除干净,无杂质引入。由于滤纸模板的引入使得SnO_2颗粒弥散分布于银基体中。随着SnO_2含量的增加,Ag-SnO_2电接触合金的硬度有上升趋势,但高氧化物含量也导致模板的分散效果变差,使得合金的电导率和致密度逐渐降低。     

Effect of dissolved metal sulphates on gas-liquid oxygen transfer in agitated quartz and pyrite slurries

A previous study on mass transfer in agitated three phase systems showed that for quartz slurries the volumetric oxygen transfer coefficient k_La [s⁻¹] decreases with increasing solids fraction, whereas pyrite particles increase the k_La value. The present study was conducted in continuation of these results and attempts to explain why the addition of pyrite particles resulted in an increase in k_La. For this purpose, the effect of ionic strength, mineral density and oxygen consumption due to homogeneous reactions was examined. Neither the high density of pyrite nor the oxygen consumption could offer an explanation for the increased k_La values obtained for pyrite slurries. The variable mineral density did not affect k_La at all, while the consumption of oxygen was not large enough to cause an enhancement of k_La. However, by reducing bubble coalescence frequency and thus bubble size, the ionic strengths found for pyrite slurries could partially explain the increase in k_La. For 15 vol.% pyrite slurries, the ionic strengths proved to account for at least 60% of the enhancement. The variable(s) and/or mechanism(s) causing the remaining 40% of the enhancement could not be identified (yet). To demonstrate the effect of ionic strength as such, various electrolytes (viz. CuSO₄, FeSO₄, ZnSO₄ and Al₂(SO₄)₃) were added to a 15 vol.% quartz slurry. For all metal sulphates, increasing the ionic strength up to about 0.25 mol/l resulted in an increase of k_La by up to a factor 2.5.     

Evaluation method of coal rank based on X-ray diffraction analysis—an example from SE Qinshui Basin

Based on analysis on X-ray diffraction, the metamorphic grade of coal in southeast Qinshui Basin was discussed, and a precise evaluation of coal rank through XRD analysis was made, in addition, the correlation of coal rank and vitrinite reflectance (R _o) was compared. XRD spectra of coal shows (002)-band and γ-band, and based on fitting calculation and multi-peak separation methods, the values of 2θ ₀₀₂ and 2θ _γ can be obtained, as well as corresponding intensities I ₀₀₂ and I _γ , consequently the coal rank can be quantized as the ratio of I ₀₀₂ and I _γ , that is coal rank=I ₀₀₂/I _γ . The research shows that the values of θ ₀₀₂ and θ _γ increase with the metamorphic grade, and a very good linear positive correlation exists between calculated Coal Rank and R _o.     

Semi-automated iron ore characterisation based on optical microscope analysis: Quartz/resin classification

The present study focused on overcoming the primary problem faced by any quantitative mineralogical study involving iron ore characterisation using a reflected light optical microscope; distinguishing the quartz mineral from the epoxy resin in digital images taken from mounted polished sections. Difficulties arise in this case because both phases reflect in the same colour intensity range. To overcome this problem, a digital image analysis system denominated Opt_-Lib was developed. In order to evaluate the system responsivity, a characterisation study and modal and liberation analyses were performed using typical Brazilian iron ore containing quartz and the main iron oxide/hydroxide minerals: magnetite, hematite, and goethite. For the system performance evaluation, these results were compared with those generated by the scanning electron microscopy (SEM)-based Mineral Liberation Analyzer for the same sample. The results show that the main advantage of the Opt_-Lib system over the SEM-based system is that it facilitates differentiation, classification, and quantification of not only the quartz mineral, but also the iron oxide/hydroxide minerals within the sample, thus providing a more precise qualitative response.     

不同密度级原煤的泥化特性

对淮南矿区不同密度级原煤进行泥化研究，并分别用激光粒度仪和 X-射线衍射仪对不同密度级原煤泥化产物的粒度组成、矿物组成进行分析。结果表明：1.5~1.6 g/cm 3原煤的泥化率较大，为10.23%；>1.7 g/cm 3原煤的泥化率最大，高达13.79%；泥化煤泥中含有大量<0.045 mm粒级的细颗粒，其中>1.7 g/cm 3原煤泥化<0.045 mm粒级煤泥中<0.025 mm的微细颗粒占99%；随原煤密度增加，泥化煤泥中石英含量逐渐增大，中间密度级原煤泥化煤泥中高岭土含量最高；泥化煤泥中主要矿物为石英和高岭土，其严重影响了煤泥水的澄清处理。     

Occurrence of iron in industrial granitic pegmatite

Granitic pegmatite is used as raw material for industrial minerals in the production of feldspar and quartz for glass, ceramic and porcelain. One of the most important quality parameters in the feldspar is the content of iron (Fe). At the Lillesand plant, Norway, pegmatite is floated to produce quartz, albite and microcline products. Fe is mostly removed through flotation and magnetic separation, but some Fe is still present in the final products, the amount depending on the raw material source. Rietveld X-ray Diffraction (XRD), Point counting by optical microscopy, and Electron Microprobe Analysis (EPMA) combined with image analysis of Back-Scatter Electron (BSE) images was used to quantify the mineralogy and to map the distribution Fe in the pegmatites. The study showed that Fe is present as mineral inclusions in feldspar, in addition to its occurrence in minor mineral components such as mica and chlorite. The frequency of Fe-mineral inclusions was higher in albite than in microcline, and they were often associated with micro-fractures and areas of alteration. These findings reveal a potential for reducing total Fe₂O₃ in the microcline products.     

细粒石英的相对润湿性及其浮选行为研究

目前测定粉体接触角的方法主要有压片法和渗透法,但由于难以制得表面光滑的样品,因此压片法应用有很大的局限性。根据Washburn原理,通过测定液体在粉体柱内产生的压差随时间的变化计算不同药剂条件下石英的相对接触角。并结合单矿物浮选试验结果来判断相对接触角是否可以准确表征矿物表面润湿性。结果表明:不同药剂条件下石英回收率与测得的接触角呈正相关,相对接触角越大,回收率越高;在pH值为12、Ca2+浓度为3.75 mmol/L、油酸钠用量为2.81 mmol/L条件下,浮选效果最好。在此基础上,使用JK99C型全自动表面张力仪测定了不同条件下溶液的表面张力,计算了气泡与颗粒黏着单位面积前后自由能的变化,从热力学角度分析了与药剂作用后石英表面润湿性变化及其浮选行为发生变化的原因。      

高纯石英全球资源现状与我国发展建议

高纯石英因其产品具有耐高温、耐腐蚀、低热膨胀性、高度绝缘性和透光性等优异的物理化学性质,广泛应用于光伏、电子信息、光通讯和电光源等高新技术产业,在战略性新兴产业中具有重要地位和作用。由于生产原料的特殊性和技术保密等原因,高纯石英的生产和出口高度集中在世界少数国家和企业。我国高纯石英对外依存度高,进口量远大于出口量,目前国内能够生产高纯石英的矿床极少。为确保战略新兴产业发展,保障高纯石英资源安全,建议将高纯石英列入关键矿产目录清单,对现有地质资料进行有针对性的梳理,加强与花岗伟晶岩型矿床对比研究,尽快建立高纯石英分级分类标准评价体系。