Comparison of energy efficiency between ball mills and stirred mills in coarse grinding

Stirred mills are primarily used for fine and ultra-fine grinding. They dominate these grinding applications because greater stress intensity can be delivered in stirred mills and they can achieve better energy efficiency than ball mills in fine and ultra-fine grinding. Investigations were conducted on whether the greater performance of stirred mills over ball mills in fine grinding can be extended to coarse grinding applications. Four different laboratory ball mills and stirred mills have been tested to grind seven ore samples with feed sizes ranging from 3.35 mm to 150 μm. A case study on full scale operations of a 2.6 MW IsaMill replacing the existing 4 MW regrind ball mill at Kumtor Gold Mine in Kyrgyzstan is also included. This paper summarizes the major findings from these investigations.     

Mineral content of some herbs and herbal teas by infusion and decoction

Sage (Salvia fruticosa L.), anise (Pimpinella anisum L.), Hawthorn (Crataegus orientalis), rosemary (Rosmarinus officinalis L.), mountain tea (Sideritis spp), basil (Ocimum basilicum L.), lime flower (Tilia cordata), nettle (Urtica dioica L.), thyme (Thymbra spicata), coriander (Coriandrum sativum L.), rosehip (Rosa canina L.), mentha (Mentha piperita L.), balm (Melissa officinalis L.), tea (Camelia sinensis L.) (Black and green), sena leaf (Casia angustifolia), camomile (Matricaria chamomilla), tarragon (Artemisia dracunculus L.), cinnamon (Cinnamomum casia) and fennel (Foeniculum vulgare L.) were used as plant material in this study. Decoction was applied to R. canina, A. dracunculus and C. casia, and infusion was applied to other plant materials. Ten, 15 and 20 min were used as a time parameter for both infusion and decection. Inductive coupled plasma atomic emission spectrometry (ICP-AEs) has been used for the determination of the elements in all infusions, decoctions and plant material.     

Impact of impregnation with boron compounds on the surface hardness of varnished wood

This study was performed to determine the impact of impregnation with boron compounds on the surface hardness of varnished wood materials. For this purpose, test specimens prepared from Oriental beech (Fagus orientalis Lipsky) and oak (Quercus petreae Lipsky), which met the requirements of ASTM D 358, were impregnated according to ASTM D 1413 with boric acid and borax by a vacuum technique. After impregnation, the surfaces were coated by cellulosic, synthetic, polyurethane, waterborne, acrylic, and acid hardening varnishes in accordance with ASTM D 3023. The surface hardness of the specimens after the varnishing process was determined in accordance with ASTM D 4366. According to the wood type, impregnation material, and varnish type, the surface hardness was highest for the oak impregnated with borax and acrylic varnish and lowest for the oak impregnated with borax and synthetic varnish. Therefore, impregnation with boron compounds showed an increasing impact on the surface hardness of the varnished wood. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Modeling and Design of Multilevel Bang–Bang CDRs in the Presence of ISI and Noise

Multilevel clock-and-data recovery (CDR) systems are analyzed, modeled, and designed. A stochastic analysis provides probability density functions that are used to estimate the effect of intersymbol interference (ISI) and additive white noise on the characteristics of the phase detector (PD) in the CDR. A slope detector based novel multilevel bang-bang CDR architecture is proposed and modeled using the stochastic analysis and its performance compared with a typical multilevel Alexander PD-based CDR for equal-loop bandwidths. The rms jitter of the CDRs are predicted using a linear jitter model and a Markov chain and verified using behavioral simulations. Jitter tolerance simulations are also employed to compare the two CDRs. Both analytical calculations and behavioral simulations predict that at equal-loop bandwidths, the proposed architecture is superior to the Alexander type CDR at large ISI and low signal-to-noise ratios.     

Effect of axial conduction on the ice crystal growth in laminar falling filmsEffet de la conduction axiale sur la vitesse de formation de cristaux de glace à l'intérieur de films tombants laminaires

A finite volume numerical code has been developed to numerically approximate the rate of ice crystal growth in a laminar falling film flowing down a cooled vertical plate. The governing energy equation contains the phase energy as the source term. Enhancement of heat transfer as a result of suspended ice crystals is accounted for in the use of effective values of thermal conductivity, viscosity, thermal diffusivity, and specific heat as function of volumetric concentration of ice crystals in the falling film. Nusselt number, overall heat transfer coefficients between the fluid and cooled plate, and ice crystal growth rate were calculated for different film thicknesses with and without axial diffusion. Nusselt number and ice crystal growth rates were found to be dependent on film thickness. Axial diffusion effects were found to be negligible for larger film thickness (large flowrate).     

Energy Dispersive X-Ray Microanalysis of Elemental Distribution in Raw and Germinated Brown Rice Varieties

In this study, the mineral composition of germinated brown rice, brown rice, and white rice was evaluated. Brown rice grain was processed through a combination of chemical pretreatment and low oxygen treatment, after which germination was confirmed through imaging under a microscope. Using energy dispersive X-ray analysis, Mg, Al, and Cl were found to be slightly higher in germinated brown rice than in brown rice and white rice. These variations in the mineral content of germinated brown rice were attributed to the joint effect of the germination process and the prior soaking. The inability of energy dispersive X-ray to detect other minerals suggested that it was not sensitive and, hence, it was not suitable for studying elemental distribution in rice grains, or maybe the elements were not present in the rice grains studied.     

Hysteresis in theIc(H) characteristics of high-temperature superconducting ceramics and thin films

The experimental hysteretic behavior of the transport critical current observed in ceramic Y-Ba-Cu-O and (Bi-Pb)-Sr-Ca-Cu-O, as well as thin film Y-Ba-Cu-O, are presented. The data are analyzed semiqualitatively. The results show certain similarities among the ceramic samples and the films.     

Antioxidant effect of essential oils of rosemary,clove and cinnamon on hazelnut and poppy oils

Antioxidant effects of essential oils from rosemary (Rosmarinus officinalis), clove (Syzygium aromaticum) and cinnamon (Cinnamomum zeylanicum) were determined on hazelnut and poppy oils. These essential oils were added to the oils at concentrations of 0.25% and 0.5%. Butylated hydroxyanisole (BHA) at 0.02% level served as standard besides the control groups for comparison. The samples were stored 50 °C in darkness for 14 days. The antioxidant activity of the essential oils was determined by measuring peroxide values (meq O₂/kg oil) at regular intervals. On the basis of peroxide value assay, the essential oils showed stronger antioxidant effect when compared to control groups. BHA was more effective than the essential oils, whilst it exhibited no antioxidative effect on the first few days of storage. Amongst the investigated essential oils, the cinnamon oil was the most effective on retarding lipid oxidation of crude oils, which was followed by clove and rosemary oils.     

Adsorption of humic acid onto chitin and chitosan

The adsorption of humic acid onto chitin and chitosan has been investigated. The uptake of humic acid from aqueous solution was determined from changes in concentration, as measured by ultraviolet-visible spectroscopy. The decrease in humic acid removal was observed with the increase in pH. A significant uptake of humic acid on both chitin and chitosan was observed. The uptake of humid acid on chitosan was greater than that on chitin. Adsorption isothermal data could be interpreted by the Langmuir and Freundlich equation. Langmuir and Freundlich constants have been determined. The experimental data of the adsorption equilibrium from humic acid solutions correlate well with the Langmuir isotherm equation, as compared to the Freundlich isotherm equation. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 69: 2305–2310, 1998