VOLUME 31, NO2, APR 2009
123
 
Optimization of Operating Process Parameters of Copper Flotation by Using Statistical Techniques

MUHAMMAD TUFAIL ,MUHAMMAD MANSOOR KHAN ,KHWAJA MUHAMMAD YAHYA ,Sardar Ali ,

Flotation process parameters were studied to concentrate major chalcopyrite (CuFeS2) sulphide copper mineral of North Waziristan. The important flotation reagents i.e. collectors, depressant, dispersant, frother and conditioning time were examined. During stepwise of flotation parameters copper was enriched from 0.9 to 20 % in a single stage cleaning with recoveries over 83 %. In order to have an insight of combined effect of all the parameters on the recovery and grade of the final product, a numbers of experiments are required to be conducted. This approach requires time and resources and still the findings are not reliable. This is due to analysis of experimental data which is based on empirical techniques. Therefore it was suggested that a statistical techniques will be used to analyze the data to project the combined effect of flotation parameters.  Hence with the available data of seven parameters Mathematical Models were developed by applying ordinary least square, OLS method for regression analysis and adopted general to simple modeling procedure. Resulting Equation (3) is statistically significant which includes the process parameters type and dosage of xanthate (Propyl Xanthate), depressant (Sodium Cyanide), Sulphidizer, (Sodium Sulphide) and pulp density. This paper comprises of five parts Introduction, discussion, methodology used for modeling and testing of the model, conceptual model, results and discussions and at end conclusions were drawn. 
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Rheological Studies and Characterization of Different Oils

AHMAD MAHMOOD ,NAVEED AKHTER ,QAZI ADNAN ,KALSOOM FARZANA ,MEHMOOD AHMAD ,

As most of the natural oils are used in cosmetics, especially in emulsions, these oils produce direct effects on the consistency and shelf life of the emulsions. In case of w/o emulsion, higher the viscosity of the oil, higher is the viscosity of emulsion. Other parameters of oil like spreadability, cloud point, pour point, saponification value, acid value, pH and specific gravity of oils also affect properties of emulsions. The purpose of this study was the characterization of different oils and their rheological properties. Eight different natural oils, namely olive, coconut, almond, castor, sesame, cotton seed, sunflower, and paraffin oils were used to study their rheology, viscosity, spreadability, cloud and pour points, saponification and acid values, pH and specific gravity. All the oils investigated were found to possess Newtonian behaviour with little deviation in olive and coconut oils. Castor oil possesses the maximum viscosity of 686.26 mPas.s among the other oils studied. Paraffin oil containing no fatty acids possesses the maximum spreadability. Castor oil has the maximum saponification value (187.02), while the paraffin oil has minimum value of 32.70. Olive oil has the maximum acid value of 1.361 among the oils investigated while paraffin oil has the minimum value of 0.224. The pH of castor oil is maximum (4.92), while that of cotton seed oil is minimum being 3.64. Paraffin oil has the maximum specific gravity value of 0.9999 while coconut oil has the minimum value of 0.9138.
Pages(201)
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Specific Heat of NH4Cl and NH4BrxCl1-x Crystals Close to the Ferro-Ordered Phase

HAMIT YURTSEVEN ,ASKIN YANIK ,

This study gives calculation of the specific heat CVI of NH4Cl and NH4BrxCl1-x under the Ising model for the transition between the disordered (D) and ferro-ordered O(F) phases in these crystalline systems. Our CVI values which we calculated for x = 0 and x = 0.04, agree both below and above Tc with the observed Cp data from the literature. Our value of a 0.1 (T < Tc and T > Tc) is in good agreement with the predicted value of 1/8 (0.125) of a 3D Ising model.
Pages(207)
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MODELLING COMPRESIVE STRENGTH OF STANDARD CEM I 42.5 CEMENT PRODUCED IN TURKEY WITH STEPWISE REGRESSION METHOD

ZEHRA ALTIN ,ABDUL KADIR TEPECIK ,SEYFETTIN ERTURAN ,

A multiple linear regression model was developed for the prediction of the 2, 7, and 28-day compressive strength of CEM I 42.5 produced in Turkey Cement Fabrics. Attention has been given to the right choice of independent variables involved in this model, especially the characteristics of the cement itself. Different combinations of variables were introduced into the model, in order to choose the variables that can properly predict the compressive strength of the cement. Multiple Linear Regression (MLR) analyses with backward stepwise were performed to describe the relationships between the compressive strength values and the chemical or physical properties of the cement. The advantage of using this technique lies in the fact that it deals simultaneously with several variables. The analysis is designed to see which factors are significant in explaining the compressive strength of the cement. The evaluation of the proposed model was performed by various statistical tests, all of which were successful. These statistical tests included: multiple correlation, test of the significance of coefficients (t-test), estimation of confidence intervals for coefficients, conditional sums of squares, R-squared and analysis of variance. Models obtained this way can predict the compressive strength of the cement with very small standard errors and coefficients of correlation of 0.9961 and 0.9955, and 0.9983, for cement strengths at 2, 7 and 28 days respectively. There was very good agreement between the strength predicted by the multiple regression model and the experimental results. These models explained only 99% of the variability in strengths.
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Thermodynamic and Solution Properties of Amphiphilic Anti-Allergic Drug Cetirizine HCl

MUHAMMAD USMAN ,ABBAS KHAN ,MOHAMMAD SIDDIQ ,

This article describes the thermodynamic and solution properties of amphiphlic drug Cetirizine HCl in the temperature range of 20-50 °C in aqueous solution. Densities, conductivities, viscosities and surface tension were measured to calculate critical micelle concentration (cmc) and in this way its surface and bulk properties have been estimated.  Various fundamental parameters such as area per molecule at air/water interface and surface excess concentration have been calculated and thermodynamics of micellization has been monitored. Our results show that Cetirizine HCl micellises through closed association process and micellization is found to be entropy driven.  The solution viscosities have been used to estimate the micellar density, partial specific volume and Intermicellar interaction parameter, KH of micelle over temperature range of 20-50 °C. From cmc we have calculated ?Hmic, ?Gmic and ?Smic
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Forming of Alumina Ceramics

FOZIA SALMAN ,BAKHT BAHADUR RANA ,WAJID ALI SHAH ,AMIR SULTAN ,FADIA SHAHEEN ,

Alumina ceramic products were made by die pressing, slip casting and extrusion. The products were tested for various physical properties such as percentage shrinkage, bulk density, apparent porosity, water absorption, scratch hardness and thermal conductivity. Increase in sintering temperature resulted in increase in percentage shrinkage of extruded rods and pressed discs from 6.6 % to 11.3 %. Scratch hardness of the extruded rod sample is around 8.5 whereas hardness values of slip cast sample is around 8 on Mohs scale. A simple method has been developed to obtain porous ceramic for thermal insulation purpose of furnaces upto 1600 oC. Porous block made has thermal conductivity value of 0.33 Wm-1K-1 and the density of 0.7 gm/cm3
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Adsorption Characteristics of Bentonites for Chromium in Waste water

NASEEM ZAHRA ,

This investigation is based on the removal of chromium (III) from waste water by batch adsorption process using natural bentonites as an adsorbent collected from various locations of Pakistan. Bentonite contains montmorillonite, which has the quality to adsorb inorganic and organic materials. The quantities of chromium (III) ions in water before and after the treatment of its standard solution (8 ppm) with different samples of bentonite were determined by atomic absorption spectroscopic method. The adsorption of chromium (III)  was studied at room temperature i.e. 30 ºC, pH 7 and 200 mesh particle size using 50 mL of metal solutions and 25 gram of  bentonite samples for one hour.  The percentage adsorption for chromium on bentonite samples was also determined. It was found that bentonite is suitable adsorbent for removal of chromium. This method is preferable over other methods as it is simple with no complex apparatus involved.
Pages(233)
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Measurement of Toxic Elements in Fish: An Indicator of Aquatic Environment

SOHAILA RAHMAN ,ISMAT FATIMA ,

Fish is a good source of protein and extensively used as a food item in Pakistan, this entails the evaluation of toxic elements (Hg, Se, As, Pb, Cd and Br) in five different species commonly consumed. Instrumental Neutron Activation Analysis (INAA) and Atomic Absorption Spectrometry (AAS) were utilized for the analysis. Our results were compared with results reported from other countries. The weekly dietary intake of toxic elements through these species has been estimated, which is well below the tolerance limit. The reliability of the techniques has been established by the use of standard reference materials. This data will serve as the baseline values and will be helpful to monitor the degree of future contamination.
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Size-Controlled Synthesis of Chromium Nanospheres and Conversion into Multipods, Rods, Rectangular Blocks, Complex Structures and Superlattice Self-Assemblies

HAFIZ RUB NAWAZ ,YI Rub ZHANG ,

In this paper we report for the first time, size-controlled synthesis of chromium nanospheres from common precursors and manipulated polyol method. These nanospheres have been further converted into multipods, nanorods, rectangular nanoblocks and micron size complex structures by simple and rapid microwave irradiations heat assisted methodology. Moreover, two dimensional (2D) superlattice self-assemblies containing monolayered mesoscopic particles have been fabricated using a solvent combination approach and the aluminum substrate without application of special polymer matrix.
Pages(240)
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Comparison of Heavy and Trace Metals Levels in Soil of Peshawar Basin at Different Time Intervals

ZAFAR IQBAL ,ANWAR AHMAD ,SHAHIDA NASREEN ZAKIR ,IHSAN IHSANULLAH ,MUHAMMAD TAHIR SHAH ,

The chemical characteristics of the soils of Peshawar basin have been evaluated in this study. Selected heavy metals i.e., copper (Cu), zinc (Zn), lead (Pb), nickel (Ni), chromium (Cr), and cobalt (Co) have been determined in the soils of horizons A (to a depth of 20 cm) and B (at a depth of 20-40 cm) from the piedmont, floodplain and lacurstrine of Peshawar basin. These samples were collected during the months of January and June of 2003 and 2004. The concentrations of these elements have been estimated to observe the changes against time. High concentrations of Cu, Pb, Ni and Cr have been found in the majority of the Peshawar floodplain soils while Zn is high in the Peshawar piedmont soil. The level of these metals reached to a high toxicity level in the soils of certain areas, which may cause drastic environmental impact on the ecosystem of the region. In addition to rapid industrialization and unplanned urbanization, the high concentration of these elements in the soils of the basin can be attributed to the weathering and erosion of the sulfides, and mafic and ultramafic rocks in the surrounding mountainous regions with greater input from the rocks of the Kohistan island arc in northern regions of the Peshawar basin. This study further suggests that there is no significant change in the concentration of these metals in the soils of the basin with the increase or decrease of the depth and also with the passage of time.
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