Study on low-grade galena-barite ore beneficiation in Khuzdar, Balochistan, Pakistan

Purpose. Galena and barite are the principal minerals of lead and barium respectively. Both minerals are used extensively in industries because of their distinct properties. In complex poly metallic ores, it is always desirable to produce separate mineral concentrates for subsequent metal extraction. Separation of two or more minerals from complex low-grade multi-metallic ore into commercial grade concentrates requires suitable process. Methods. This research work is centered on development a suitable process for the beneficiation of a low-grade galena-barite ore originating from Khuzdar region (Balochistan Province, Pakistan). Findings. The low-grade ore assaying 39.90% Pb and 24.64% BaSO4 was beneficiated on bench-scale by sequential froth flotation process to recover valuable galena and barite concentrates. The important variables of froth flotation process such as feed size, pulp pH, pulp density, impeller speed, type and quantities of flotation reagents, pulp conditioning time and froth collecting time were optimized to achieve maximum recovery and grade of both concentrates. The rougher galena and barite concentrates were re-ground separately and subjected to one cleaning flotation to obtain better grade final concentrates of respective minerals. Originality. A process flow-sheet was designed in the light of this study. Practical implications. Froth flotation experiments showed that a galena concentrate containing 77.38% Pb with recovery of 90.64% and a barite concentrate assaying 90.23% BaSO4 with recovery of 80.16% could be recovered from this ore. Both the concentrates fall in the category of metallurgical and chemical grades and are suitable for industrial applications.Мета. Підвищення якості низькосортної галеніт-баритової руди, знайденої в Хуздарском районі провінції Белуджистан (Пакистан), до концентрату металургійного якості, що містить більше 70% Pb, із використанням методу пінної флотації. Методика. Масова проба галеніт-баритової руди вагою близько 100 кг була відібрана з шахти Мал-Хор на північному заході від Хуздару та доставлена в лабораторію переробки мінералів MPRC, PCSIR Lahore для проведення досліджень. Зразок підданий первинному подрібненню із використанням щокової дробарки з наступним вторинним подрібненням із використанням валкової дробарки. Зразок до і після флотації піддавався комплексному хімічному і рентгеноструктурному аналізу (XRD). Флотаційні випробування проводилися на лабораторній флотаційній машині D-12. Після визначення оптимального помелу були проведені випробування для оптимізації щільності пульпи, рН пульпи, швидкості перемішування, кількості доданих реагентів, часу флотації й часу кондиціонування. Результати. Встановлено, що вміст свинцю та барію в поліметалічній руді є достатнім для промислового використання. Отримано оптимальну ступінь подрібнення і відновлення при розмірі подачі 80% мінус 200 меш. Виявлено, що збільшення щільності пульпи дещо знижується при збільшенні В/Т з 20 до 35%, але відновлення збільшується, а максимальне відновлення досягнуто при 30%. При використанні для коригування рН пульпи етілксантата калію, а потім бариту з олеатом натрію, виявлено, що при постійних умовах розміру часток і співвідношення твердої речовини та рідини максимально повторне покриття галену досягається при рН 8.5 і бариту при рН 10.0. Було відзначено, що невелика зміна pH значно змінила ступінь і відновлення. Розкрито вплив швидкості перемішування робочого колеса й відзначено, що оптимальною швидкістю на грубій стадії є швидкість 1100 об/хв, а на стадії очищення – 1000 об/хв. Доведено, що методом пінної флотації з даної руди можна отримати концентрат галеніту із вмістом 77.38% Pb і ступенем відновлення 90.64%, а також концентрат бариту із вмістом 90.23% BaSO4 і ступенем відновлення 80.16%. Наукова новизна. Встановлено характер впливу специфічних речовин, що поліпшують показники про-процесу флотації, які сприяють якісному відділенню цінних компонентів руди від порожніх домішок. Практична значимість. Розроблено принципову схему процесу збагачення галеніт-баритової руди на основі пінної флотації в замкнутому циклі. Отримані концентрати галеніту й бариту відповідають необхідним металургійним і хімічним стандартам та можуть знайти промислове застосування.Цель. Повышение качества низкосортной галенит-баритовой руды, найденной в Хуздарском районе провинции Белуджистан (Пакистан), до концентрата металлургического качества, содержащего более 70% Pb, с использованием метода пенной флотации. Методика. Массовая проба галенит-баритовой руды весом около 100 кг была отобрана из шахты Мал-Хор к северо-западу от Хуздара и доставлена в лабораторию переработки минералов MPRC, PCSIR Lahore для проведения исследований. Образец подвергнут первичному дроблению с использованием щековой дробилки, с последующим вторичным дроблением с использованием валковой дробилки. Образец до и после флотации подвергался комплексному химическому и рентгеноструктурному анализу (XRD). Флотационные испытания проводились на лабораторной флотационной машине D-12. После определения оптимального помола были проведены испытания для оптимизации плотности пульпы, рН пульпы, скорости перемешивания, количества добавленных реагентов, времени флотации и времени кондиционирования. Результаты. Установлено, что содержание свинца и бария в полиметаллической руде является достаточным для промышленного использования. Получена оптимальная степень измельчения и восстановления при размере подачи 80% минус 200 меш. Выявлено, что увеличение плотности пульпы несколько снижается при увеличении В/Т с 20 до 35%, но восстановление увеличилось, а максимальное восстановление достигнуто при 30%. При использовании для корректировки рН пульпы этилксантата калия, а затем барита с олеатом натрия, обнаружено, что при постоянных условиях размера частиц и соотношения твердого вещества и жидкости максимальное повторное покрытие галена достигается при рН 8.5 и барита при рН 10.0. Было отмечено, что небольшое изменение pH значительно изменило степень и восстановление. Раскрыто влияние скорости перемешивания рабочего колеса и отмечено, что оптимальной скоростью на грубой стадии является скорость 1100 об/мин, а на стадии очистки – 1000 об/мин. Доказано, что методом пенной флотации из данной руды можно получить концентрат галенита с содержанием 77.38% Pb и степенью восстановления 90.64%, а также концентрат барита с содержанием 90.23% BaSO4 и степенью восстановления 80.16%. Научная новизна. Установлен характер влияния специфических веществ, улучшающих показатели процесса флотации, что способствовало качественному отделению ценных компонентов руды от пустых примесей. Практическая значимость. Разработана принципиальная схема процесса обогащения галенит-баритовой руды на основе пенной флотации в замкнутом цикле. Полученные концентраты галенита и барита соответствуют металлургическим и химическим стандартам и могут найти промышленное применение.The authors are grateful to Associate Professor, Dr. Zulifqar Ali, Department of Mining Engineering, University of Engineering and Technology (UET), Lahore for his valuable support/ cooperation in X-ray diffraction (XRD) analysis and mineralogical evaluation of ore

high temperature cavity receiver integrated with a short term storage system for solar mgts heat transfer enhancement

Abstract Dish-Micro Gas Turbines (MGTs) can be promising systems for power production at small-scale by concentrated solar radiation. Several high-temperature solar receivers have been already designed for such plants, however, nowadays, none of them can assure the proper thermal inertia to level the effects of solar radiation fluctuations on engine performance and safety. In this paper, a solar receiver integrated with a short-term storage system based on high-temperature Phase-Change Materials (PCMs), is proposed. On the basis of a previous preliminary component design and analysis, the receiver geometry has been modified to improve storage capability and heat transfer to the working fluid, reducing temperatures on the irradiated surface making them compatible with material properties and reducing also temperature gradients inside the PCM. Six different geometries, varying length, opening and shape of a front cavity have been analyzed by means of CFD methods. All the configurations have shown a satisfactory behavior in terms of working fluid outlet temperature, storage capabilities and maximum temperatures reached on the surface and inside the receiver. In particular, among them, three geometries can be considered the most promising ones

Haematological Indices and Carcass Composition of African Catfish Clarias gariepinus (Burchell, 1822) Fingerlings Fed with Fluted Pumpkin Leaf (Telfairia Occidentalis) as Feed Additives

A feeding trial was carried out for 56 days to ascertain the effects of Telfairia occidentalis (fluted pumpkin) as a feed additive on the haematological profile and nutrients value of Clarias gariepinus carcass. C. gariepinus fingerlings (mean body weight 9.6g) were randomly distributed in plastic bowls at nine fish per bowl in triplicates. Five diets designated as D1 to D5 with 40% crude protein containing 0, 50, 100, 150, and 200g/kg of T. occidentalis leaf powder were fed to C. gariepinus fingerlings at 5% body weight per day. The results showed that T. occidentalis additive significantly (P≤0.05) improved the haematological parameters of the fish. The mean value of white blood cells (WBC) count (μL) in the diets fed with T. occidentalis were significantly higher (D2-D5 : 870.20, 864.80, 840.30, 876.40, respectively) than the diet without T. occidentalis (D1 783.15). A similar trend was observed in PCV, MCV, MCHC, MCH, and platelets. However, HB D1 (control) had higher values than the diet containing T. occidentalis. Meanwhile, in carcass quality, there was an increase in the crude protein of all the fish but the group that consumed T. occidentalis had a higher carcass crude protein and lower lipid, while the control had a higher lipid value. Meanwhile, the initial values obtained before the feeding trials had lower crude protein and higher lipid value when compared with the fish that was fed with the experimental diet. In conclusion, T. occidentalis leaf meal can be utilized to improve the haematological  parameters of the fish, with an increase in the WBC there is a high possibility of the fish to withstand pathogenic attacks because Blood is a major parameter that determines the physiological, immune , and nutritional status of an organism, also WBC are important blood  constituents for defense against diseases, pathogens and unwanted foreign bodies in an organism

Forecasting rainfed sorghum yield using satellite-derived vegetation indices with limited ground-based information in Gadarif region, eastern Sudan

A practical crop growth and yield monitoring system based on satellite data is required and fundamental not only for precision farming, but also very useful for global food security enhancement. This study was performed to determine the optimal vegetation index and also to identify the best time for making a reliable crop yield forecast in one of the major sorghum-growing region (Gedarif State, Sudan). The study was also aimed to develop a simple yield prediction model which was later validated using an official yield data acquired during 2013 and 2014 cropping seasons from the Department of Information System and Statistical Analysis of the State Ministry of Agriculture, Gedarif State. The study used NASA’s multi-temporal MODerate resolution Imaging Spectroradiometer (MODIS) land products with limited ground information. Relationship between sorghum yield and crop reflectance indicated that normalized difference vegetation index (NDVI) at the third dekad of September (Sep.III) is the most appropriate to develop sorghum yield prediction model with higher R2 value of 0.77 (p<0.05) compared to other vegetation indices (normalized ratio vegetation index, NRVI and soil-adjusted vegetation index, SAVI). The plotting of estimated yield against actual yield during 2013 and 2014 cropping seasons revealed strong positive and linear correlations (R2 = 0.64 (p=0.06) and 0.74 (p<0.05), respectively with average R2 = 0.71 (p<0.001) for both seasons. This study concluded that a good prediction of rainfed sorghum yield could be achieved more than 30 days before harvesting with quick, accurate and cost-effective method compared to traditional field surveys

Mortality pattern among tuberculosis patients on treatment in Nigeria: A systematic review and meta-analysis

Background: Tuberculosis (TB) has continued to be associated with a substantial number of deaths, even in the era of effective antimicrobials. Nigeria is one of the countries with a high tuberculosis burden and has sub-optimal documentation of TB related deaths. Vital statistics/registration is not robust, and mortality surveys are rarely undertaken. In this study, we aimed to determine a precise estimate of TB related deaths on treatment and the trends in death rate while on TB treatment in Nigeria. Methods: We searched electronic databases for eligible studies from 1st January 2000 to 31st December 2017. We generated pooled death rate estimates using random-effects models and determined trends using meta-regression. Results: We identified 546 studies, of which 28 fulfilled the criteria for quantitative analysis. Overall, studies reported on 64,999 individuals. The pooled TB death rate during treatment was 6.6% (95% CI; 5.2-8.1%). There was a non-significant rise in TB related deaths on treatment of 0.2% per year (p-value = 0.454). Conclusion: We found a low TB related deaths on treatment, death rate and slight temporal rise over the study years. There is a need for continuous vital registration, including TB related death, and mortality survey among TB patients

Valence-quark distributions in the pion

We calculate the pion's valence-quark momentum-fraction probability distribution using a Dyson-Schwinger equation model. Valence-quarks with an active mass of 0.30 GeV carry 71% of the pion's momentum at a resolving scale q_0=0.54 GeV = 1/(0.37 fm). The shape of the calculated distribution is characteristic of a strongly bound system and, evolved from q_0 to q=2 GeV, it yields first, second and third moments in agreement with lattice and phenomenological estimates, and valence-quarks carrying 49% of the pion's momentum. However, pointwise there is a discrepancy between our calculated distribution and that hitherto inferred from parametrisations of extant pion-nucleon Drell-Yan data.Comment: 8 pages, 3 figures, REVTEX, aps.sty, epsfig.sty, minor corrections, version to appear in PR

An empirical investigation of tourism-led growth hypothesis in the European countries: evidence from augmented mean group estimator

Due to urbanization and the need for people to go from one country to another either for commercial purpose or tourism, it is therefore important to determine the extent to which tourism contributes to growth. This article aims to investigate the tourism-led growth hypothesis in a sample of 34 European countries utilizing the yearly data from 1995 to 2015. The research work makes use of 8 tourism indicators, which cover different dimensions of tourism sector development such as foreign visitors' spending, and international tourist arrival. For empirical analysis, the study accounts key determinants of growth such as capital, labor and energy (renewable and non-renewable) consumption. The results from common correlated effects (CCE) augmented mean group (AMG) and groped-mean estimators confirms that there is a positive relationship between tourism, labour, capital and GDP insinuating the presence of tourism-led growth hypothesis in the European countries. Also, findings from the FMOLS show that changes in the variables leads to a proportional change in GDP. Specifically, the evidence shows that the tourism indicators play an indispensable role in promoting economic development, along with energy consumption, capital, and labor. Sustainable Combating environmental issues associated with foreign arrivals, renewable energy consumption should be encouraged to reduce environmental externalities to ensure sustainable environments for businesses and tourists’ arrivals

Electromagnetic form factors of light vector mesons

The electromagnetic form factors G_E(q^2), G_M(q^2), and G_Q(q^2), charge radii, magnetic and quadrupole moments, and decay widths of the light vector mesons rho^+, K^{*+} and K^{*0} are calculated in a Lorentz-covariant, Dyson-Schwinger equation based model using algebraic quark propagators that incorporate confinement, asymptotic freedom, and dynamical chiral symmetry breaking, and vector meson Bethe-Salpeter amplitudes closely related to the pseudoscalar amplitudes obtained from phenomenological studies of pi and K mesons. Calculated static properties of vector mesons include the charge radii and magnetic moments: r_{rho+} = 0.61 fm, r_{K*+} = 0.54 fm, and r^2_{K*0} = -0.048 fm^2; mu_{rho+} = 2.69, mu_{K*+} = 2.37, and mu_{K*0} = -0.40. The calculated static limits of the rho-meson form factors are similar to those obtained from light-front quantum mechanical calculations, but begin to differ above q^2 = 1 GeV^2 due to the dynamical evolution of the quark propagators in our approach.Comment: 8 pages of RevTeX, 5 eps figure

Effect of Long-Term Climbing Training on Cerebellar Ataxia: A Case Series

Background. Efficient therapy for both limb and gait ataxia is required. Climbing, a complex task for the whole motor system involving balance, body stabilization, and the simultaneous coordination of all 4 limbs, may have therapeutic potential. Objective. To investigate whether long-term climbing training improves motor function in patients with cerebellar ataxia. Methods. Four patients suffering from limb and gait ataxia underwent a 6-week climbing training. Its effect on ataxia was evaluated with validated clinical balance and manual dexterity tests and with a kinematic analysis of multijoint arm and leg pointing movements. Results. The patients increased their movement velocity and achieved a more symmetric movement speed profile in both arm and leg pointing movements. Furthermore, the 2 patients who suffered the most from gait ataxia improved their balance and 2 of the 4 patients improved manual dexterity. Conclusion. Climbing training has the potential to serve as a new rehabilitation method for patients with upper and lower limb ataxia

An integrated map of structural variation in 2,504 human genomes

Structural variants are implicated in numerous diseases and make up the majority of varying nucleotides among human genomes. Here we describe an integrated set of eight structural variant classes comprising both balanced and unbalanced variants, which we constructed using short-read DNA sequencing data and statistically phased onto haplotype blocks in 26 human populations. Analysing this set, we identify numerous gene-intersecting structural variants exhibiting population stratification and describe naturally occurring homozygous gene knockouts that suggest the dispensability of a variety of human genes. We demonstrate that structural variants are enriched on haplotypes identified by genome-wide association studies and exhibit enrichment for expression quantitative trait loci. Additionally, we uncover appreciable levels of structural variant complexity at different scales, including genic loci subject to clusters of repeated rearrangement and complex structural variants with multiple breakpoints likely to have formed through individual mutational events. Our catalogue will enhance future studies into structural variant demography, functional impact and disease association. © 2015 Macmillan Publishers Limited. All rights reserved