An approach to modelling industrial unit processes: application to a spiral concentrator for minerals

A suite of computer models which simulate process operations in common use in the minerals processing industry is being developed. Application of the models is described with reference to a particular process device, the spiral concentrator. The paper sets out to explain the basic strategy behind the unit process modelling approach and discusses in detail the overall model structure adopted. The model aims to provide a set of equations, with sufficient physical significance to give a reasonable fit to any specific data set, and which can be systematically adjusted (through auxiliary models, user judgement and experience) to provide meaningful performance predictions over a broad range of operating conditions. The approach is thought to be applicable to a wide variety of processes. The model has been tested using a variety of ores, separated on plant-scale equipment and practical examples are given. The scope and limitations of the method are reported, drawing on the results of parallel experimental work. The extent to which this kind of approach can be used as a predictive tool in process design applications and in the day-to-day running of mineral processing plant is discussed.     

Identification and microanalysis of mineral fibers by LAMMA

Summary Analysis of asbestos and glass fibers obtained by either environmental sampling or after longer periods of deposition in human and animal tissue revealed that the latter undergo changes of their chemical composition. Electron microscopy and LAMMA were used in these investigations. The extent of fiber dissolution could be assessed. Some fibers remained chemically unchanged. In certain fibers only some elements were partially leached out whereas in other fibers the majority of metallic elements were eluted.

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Identifizierung und Mikroanalyse von mineralischen Fasern mit Hilfe von LAMMA

     

基于矿物质定量热分析的灰熔融反应动力学

利用矿物质定量热分析理论对三种典型煤样灰熔融过程进行了详细分析,借助化学反应动力学相关概念,计算了灰样熔融反应动力学参数,结果表明:灰样熔融过程呈明显的三阶段反应过程,即初始熔融阶段、矿物共熔阶段以及熔融末期;熔融初始阶段反应活化能均大于后面两个阶段,矿物共熔过程活化能较初始阶段明显下降;在理论上证明了灰熔融逐渐加剧的过程。     

关于“评测指标权重确定的结构熵权法”的注记

本文基于文献[1]所提出的观点,根据熵理论和德尔斐专家调查法,对文献[1]所提出的方法进行了改进,得到了改进的结构熵权法,并运用此方法对环保项目指标进行权重确定,同时与经典的德尔斐专家调查法确定的权重进行比较,并对二者的差异作出了合理解释。     

Typical Frobenius coverings

A covering p from a Cayley graph Cay（G, X） onto another Cay（H, Y） is called typical Frobenius if G is a Frobenius group with H as a Frobenius complement and the map p ： G →H is a group epimorphism. In this paper, we emphasize on the typical Frobenius coverings of Cay（H, Y）. We show that any typical Frobenius covering Cay（G, X） of Cay（H, Y） can be derived from an epimorphism /from G to H which is determined by an automorphism f of H. If Cay（G, X1） and Cay（G, X2） are two isomorphic typical Frobenius coverings under a graph isomorphism Ф, some properties satisfied by Фare given.     

Preface - Contributions to the 8th International Conference on Applications of Stable Isotope Techniques to Ecological Studies (ISOECOL), Brest,France, 20–24 August 2012

Abstract

The study is focused on the dolomite-limestone drinking water aquifers in the Bo? massif, as well as on the andesite-aquifer containing mineral water in the vicinity of Roga?ka Slatina. The catchment area is limited and both drinking and mineral waters are discharged from the same source. The increasing use of deeper aquifers means that natural springs and shallow wells have become sporadic. Consequently new techniques of investigating recharge and aquifer capacity are required which can augment classical hydrogeological methods.

Current research into the mineral and drinking water aquifers in the area of Roga?ka Slatina is based on measuring the isotopic composition of light elements, (H, C and O) as natural tracers. It can be concluded that all the groundwaters investigated are typically infiltrated meteoric water. The drinking waters are generally young and were infiltrated up to about ten years ago. The isotopic composition of oxygen is similar to recent precipitation (δ¹⁸O = -9.3 ± 1‰) and the drinking waters contain tritium. It was found that exploited mineral waters recharged aquifers during colder periods; they are only partly mixed with younger water as can be seen from the isotopic composition of oxygen and corrected ¹⁴C dating, which puts the mean ages at between around 100 and 8,000 years. With regard to the “nuclear period” (1960-64) with abnormally high tritium activities of precipitation, all the waters examined can be divided into at least three main infiltration groups depending on their measured tritium content: around 35 years old (> 80 T.U.), older (> 10 T.U.) and younger (10 to 60 T.U.). Detailed dating is possible following the above classification. Isotope exchange between rocks and water is negligible and therefore very deep circulation at the temperature conditions above 80°C does not occur. Dissolved inorganic carbon (DIC) in the drinking waters is the result of equilibrium reactions between carbonates and organically produced CO₂ (δ¹³C = - 14.5 ± ‰), while the high concentrations of DIC (δ¹³C = + 3 ±‰) and CO₂ observed in the mineral waters are generated by low-temperature decarbonatization processes and indicate the deep origin of CO₂, from where gas migrates into mineral water aquifers.

Correlation analyses between the parameters studied are performed. Useful conclusions concerning water circulation and the capacities of aquifer reservoirs are described which support the future optimal pumping of mineral and drinking water at the limited catchment area of Roga?ka Slatina and Bo?.     

Atomistics of helium diffusion in copper and tungsten

Using previously determined interatomic potentials, the activation energy for migration of a single substitutional helium atom in copper and tungsten has been determined. The mechanism of migration involves the jump of the helium atom out of the vacancy concurrent with the jump of a host atom into that vacancy. The helium then occupies the vacant site created by the jumping host atom, resulting in a substitutional helium at a distance of √2 r ₀ (√3r ₀) from its original site in copper (tungsten). The rate-limiting step in the process is found to be the jump of the helium out of the vacancy, the activation energy for which is 2.15 eV in copper and 4.69 eV in tungsten.     

蛭石对高钠高钙准东煤结渣特性影响研究

采用一维沉降炉,辅以灰熔点仪的实验方法,将蛭石与高钠高钙准东煤掺混燃烧,研究其对高钠高钙准东煤结渣特性的影响。结果表明,随着蛭石掺烧量的提高,灰熔点温度呈现先降低后升高的趋势,当掺烧量为6%时灰熔点温度最低;蛭石掺烧量越高,高钠高钙准东煤结渣情况改善越明显,当掺烧量达到4%时,渣样变得疏松多孔,质地变脆,渣样与沉积探针之间的黏附性较弱,极易通过吹灰除去,建议蛭石掺烧量为4%;煤灰中原始矿物质以石英、钙铝黄长石或钙黄长石以及辉石类的低熔点矿物质为主,掺烧蛭石后,含钠的绿辉石矿物质被转化为韭闪石,含铁的斜辉石、赤铁矿等矿物质被转化为铁橄榄石,渣样中的矿物质均以高熔点的镁橄榄石为主;蛭石具有固钠的作用,取样温度越低,蛭石掺混量越高,其固钠效果越明显。     

Raman spectroscopy of hydrogen arsenate group (AsO3OH)2− in solid‐state compounds: cobalt‐containing zinc arsenate mineral,koritnigite (Zn,Co)(AsO3OH)·H2O

Raman spectra of two well‐defined types of koritnigite crystals from the Jáchymov ore district, Czech Republic, were recorded and interpreted. No substantial differences were observed between both crystal types. The observed Raman bands were attributed to the (AsO₃OH)²⁻ stretching and bending vibrations as well as stretching and bending vibrations of water molecules and hydroxyl ions. The non‐interpreted Raman spectra of koritnigite from the RRUFF database and the published infrared spectra of cobaltkoritnigite were used for comparison. The O H···O hydrogen bond lengths in the crystal structure of koritnigite were inferred from the Raman spectra and compared with those derived from the X‐ray single‐crystal refinement. The presence of (AsO₃OH)²⁻ units in the crystal structure of koritnigite was proved from the Raman spectra, which supports the conclusions of the X‐ray structure analysis. Copyright © 2010 John Wiley & Sons, Ltd.