Effects of Increasing Chitosan Nanofibre Volume Fraction on the Mechanical Property of Hydroxyapatite

This work attempted to synthesize chitosan (CH) nanofibre from crab shell and hydroxyapatite, HA, from limestone with the objective of studying the effects of increasing volume fraction of chitosan nanofibre on the mechanical properties of HA. Mechanical characterization of different fraction composite was carried out to study the effects of increasing volume fraction of chitosan nano fibre on the mechanical properties of HA. In addition, surface characterization of the composite was carried out using Fourier Transform Infrared Spectrometry, FT-IR. Results obtained indicated that the optimum mechanical properties were obtained at a volume fractions of 30: 70, CH: HA respectively; average compressive strength of 10.12 MPa; average tensile strength of 173.9 MPa; average hardness value of 420.80 HV; average fracture toughness of 14.72 MPa.m1/2; average elastic modulus of 0.1583 GPa and average bending strength of 157.96 MPa were obtained for this optimum volume fractions. Increasing volume fractions of chitosan nanofibre was therefore found to result in decrease in compressive strength, hardness and elastic modulus of HA while its tensile strength, bending strength and fracture toughness increased. The FTIR revealed that possible interaction between the NH2 group and the primary and secondary –OH group of CH with Ca2+ (metal coordination interaction) of HA might be responsible for the higher mechanical property of HA. In conclusion, it was found that increasing chitosan volume fraction in chitosan/HA composite results in increasing strength of hydroxyapatite, consequently enhancing its load bearing ability

Extraction of a low grade zinc ore using gravity and froth flotation methods

Extraction of low grade zinc ore found in Gumau- Toro town was carried out using gravity and froth flotation methods. Analysis of the chemical composition reveals that the crude ore contains 20.20% Zinc and other related minerals such as  66.72% SiO2, 2.36%.Pb, 16.62%Fe, 0.001%Ag, these are impurities that  hindered the grade of zinc in this ore from appreciating. Fractional and grain sieve size results revealed that the liberation size of the ore is at -355+250μm assaying 32.41%Zn. At this liberation sieve size, the low grade zinc ore was subjected to four different beneficiation methods using five kilograms (5kg) each as charge into  Wilfley shaking Table, Humphrey spiral concentrator, Air floating Machine and one kilogram (1kg) for froth flotation. Resulting products (concentrate and tailing) from these processes were analyzed using instrumentation method. Percentage recovery of each applied process was calculated. This was used to ascertain that the use of froth flotation that gives 74.32%Zn at a recovery of 84.62% stands out the best method for zinc extraction towards value addition to the low grade crude zinc ore. ©JASEMKey words: Extraction, Upgrading, Gravity, Froth flotation, Mineral, Fractional  analysis.