An Assessment of Cleaning Amenability of Salt Range Coal Through Physical Cleaning Methods

Representative coal samples from the eastern salt range (Modern Engineering and Kishor coal mines, Pakistan) and the central salt range (Punjmin coal mine, Pakistan) were collected and examined for their chemical composition. The chemical characteristics indicate that the salt range coal belongs to sub-bituminous category. Washability analysis on selected coal samples (6.70 ´ 0.212 mm) using zinc chloride solution with a specific gravity from 1.3 to 1.7 were executed. The results classify the central salt range coal as easily washable while, the Eastern salt range coal as moderately difficult to wash. Jigging, shaking table and spiral techniques were applied to check the cleaning amenability of the salt range coal through these techniques. Among these techniques, shaking table revealed the most promising results for all the three coals. Punjmin coal showed the maximum rejection of ash of 55% and that of total sulphur of 74% with a recovery of 46%.

Pyrolysis Characteristics of Blends from Coal and Polyethylene

Shenfu coal (SFC) was pulverized and modified with planetary ball mill. Maceral separation of the coal was performed by means of density gradient centrifuge in zinc chloride solution. Blends from low density polyethylene (LDPE) and parent coal powder, iron ions loaded coal powder, or floated maceral fractions were prepared in co-rotation twin-screw extruder. Pyrolysis characteristics were investigated based on differential scanning calorimetry (DSC) measurements, apparent activation energies were calculated according to Kissiger and Ozawa methods. It is found that chemical interaction between SFC and LDPE is attributed to their overlapped pyrolysis temperature regions, leading to instant and rapid propagation and termination of macromolecular chains produced in the co-pyrolysis. Iron ions loaded in the coal can facilitate formation of radicals with acceleration in chemical reaction rates. Thermal degradation of LDPE is rate-determining step in co-pyrolysis of the coal and the polyethylene. Maceral fraction floated in 1.25g·cm-3zinc chloride solution is more reactive with polyethylene due to its higher content in aliphatic hydrocarbon and hydrogen, playing a role of excellent hydrogen donor to LDPE in the co-pyrolysis.

Microstructures and Photoluminescence of Electrochemically-Deposited ZnO Films on Porous Silicon and Silicon

ZnO films covered with microrods were grown on silicon and porous silicon through electrochemical deposition with silicon or porous silicon as cathode, a platinum wire as anode, and zinc chloride solution of 0.05mol/L as electrolyte. The morphologies by SEM and the crystal structures by XRD were studied. The photoluminescence spectra were also measured. And the mechanisms of the growth and the photoluminescence of the ZnO thin films were analyzed and compared. Studies showed that the luminous intensity of ZnO thin films is different under different conditions, but its peak is located between 370-385nm, luminous intensity of the ZnO film deposited on porous silicon and then annealed is weaker.