Evaluation of flocculation characteristics of kaolinite dispersion system using guar gum:A green flocculant

This paper reports the systematic investigation on the flocculation,sedimentation and consolidation characteristics of kaolinite using guar gum as a green flocculant.In-situ flocculation behavior of kaolinite at various pH,guar gum dosages,and ionic strength were studied using a light scattering technique.The effect of these parameters on the settling rate,solid consolidation,and supernatant liquid clarity was recorded.The morphology of kaolinite and flocculated kaolinite aggregates were analyzed using FESEM.The morphology studies suggest that it is poorly crystalline with multiple steps on edge,broken edge;laminar with high aspect ratio and have rough basal surface.The complex irregularity on the basal surface and the presence of multiple steps in the edges,broken edges(hydroxyl groups)have facilitated the guar gum adsorption.The isoelectric point of kaolinite is pH 3.96.The pH,ionic strength and flocculant dosage have a significant effect on the kaolinite settling rate.The guar gum has exhibited excellent turbidity removal efficiency at pH 5.The turbidity removal is inefficient at pH 10.However,guar gum has shown high turbidity removal with 80%transmission at pH 10 in the presence of a KNO3 electrolyte.

Magnetic and flotation studies of banded hematite quartzite (BHQ) ore for the production of pellet grade concentrate

To identify and establish beneficiation techniques for banded hematite quartzite （BHQ） iron ore, a comprehensive research on BHQ ore treatment was carried out. The BHQ ore was assayed as 38.9wt% Fe, 42.5wt% SiO2, and 1.0wt% Al2O3. In this ore, hematite and quartz are present as the major mineral phases where goethite, martite, and magnetite are present in small amounts. The liberation of hematite particles can be enhanced to about 82% by reducing the particle size to below 63 μm. The rejection of silica particles can be obtained by magnetic and flotation separation techniques. Overall, the BHQ ore can be enriched to 65.3wt% Fe at 61.9% iron recovery. A flowsheet has been suggested for the commercial exploitation of the BHQ ore.

Microstructure and Mechanical Properties of Mg–7.4% Al Alloy Matrix Composites Reinforced by Nanocrystalline Al–Ca Intermetallic Particles

Mg-7.6% Al （in mass fraction） alloy matrix composites reinforced with different volume fractions of nano- crystalline Al3Cas particles were synthesized by powder metallurgy, and the effect of the volume fraction of reinforcement on the mechanical properties was studied. Room temperature compression test reveals considerable improvement on mechanical properties as compared to unreinforced matrix. The compressive strength increases from 683 MPa for unre- inforced alloy matrix to about 767 and 823 MPa for the samples having 20 and 40 vol% of reinforcement, respectively, while retaining appreciable plastic deformation ranging between 12 and 24%. The specific strength of the composites increased significantly, demonstrating the effectiveness of the low-density AlaCas reinforcement.

Improved Fracture Toughness of Cryorolled and Room Temperature Rolled 6082 Al Alloys

In the present work, 6082 Al alloy has been rolled to 40% and 70% thickness reductions at the cryogenic and room temperatures for the improvement in mechanical and fracture toughness properties. All cryorolled samples are subjected to aging at different temperatures, i.e., 140, 160, and 190 ℃ to improve the strength, ductility, and fracture toughness. The microstructures of the cryorolled （CR） and room temperature rolled （RTR） alloy after 40% and 70% thickness reductions are characterized by FE-SEM to reveal the modes of failure. The results show that the starting bulk Al alloy specimen is fractured in total ductile manner, consisting of well-developed dimples over the entire surface. The mechanical properties and fracture toughness of the 70% CR alloy are found better than 70% RTR alloy due to higher dislocations density and formation of sub-grain structures in the CR alloy.

Influence of in-flight particle state diagnostics on properties of plasma sprayed YSZ-CeO_(2) nanocomposite coatings

This article describes the influence of controlling in-flight hot particle characteristics on properties of plasma sprayed nanostructured yttria stabilized zirconia(YSZ)coatings.This article depicts dependence of adhesion strength of as-sprayed nanostructured YSZ coatings on particle temperature,velocity and size of the splat prior to impact on the metallic substrate.Particle temperature measurement is based on two-color pyrometry and particle velocities are measured from the length of the particle traces during known exposure times.The microstructure and adhesion strength of as-sprayed nano-YSZ coatings were studied.Field emission scanning electron microscopy results revealed that morphology of coating exhibits bimodal microstructure consisting of nano-zones reinforced in the matrix of fully melted particles.The coating adhesion strength is noticed to be greatly affected by the melting state of agglomerates.Maximum adhesion strength of 42.39 MPa has been experimentally found out by selecting optimum levels of particle temperature and velocity.The enhanced bond strength of nano-YSZ coating may be attributed to higher interfacial toughness due to cracks being interrupted by adherent nano-zones.

PARAMETER AND INTERACTION STUDY OF EDGE CRACK PROBLEM USING MESHFREE METHOD

In this work,element free Galerkin method(EFGM)has been used to obtain the solution of edge crack problem under mechanical loads as it provides a versatile technique to model static as well as moving crack problems without any requirement of remeshing.At first,some techniques are presented for enriching the EFG approximations near the crack tip such as extrinsic and intrinsic enrichment.Extrinsic enrichment involves the addition of solution form to the trial function,whereas the EFG basis is expanded to include few terms from crack tip solution in intrinsic enrichment.Apart from enrichment techniques,four basic techniques of smoothing meshless approximations near nonconvex boundaries are also presented such as diffraction,transparency,see through and wedge model.These techniques are then used for the parameteric analysis of an edge crack problem under mode-1 loading and results obtained using different approaches are compared with each other as well as with exact solution.Among these techniques,the extrinsic PU enrichment technique was found to be more accurate as compared to other approaches.Extrinsic PU enrichment technique has also been used for the analysis of a shear edge crack problem.In all these techniques,the value of mode-1 stress intensity factor and mode-2 stress intensity factor has been evaluated by interaction integral approach.Effect of crack orientation is also studied for different cases.

A model for expansion ratio in liquid-solid fluidized beds

Liquid-solid fluidized beds are used in mineral processing industries to separate particles based on parti- cle size, density, and shape. Understanding the expanded fluidized bed is vital for accurately assessing its performance. Expansion characteristics of the fluidized bed were studied by performing several experi- ments with iron ore, chromite, quartz, and coal samples. Using water as liquid medium, experiments were conducted to study the effects of particle size, particle density, and superficial velocity on fluidized bed expansion. The experimental data were utilized to develop an empirical mathematical model based on dimensional analysis to estimate the expansion ratio of the fluidized bed in terms of particle character- istics, operating and design parameters. The predicted expansion ratio obtained from the mathematical model is in good agreement with the experimental data.