a b s t r a c t
A slurry nebulisation technique was applied for elemental analysis of bituminous coals SARM 18, SARM
19 and four coals from three different seams in Witbank, South Africa, by inductively coupled plasma
optical emission spectroscopy (ICP-OES). Major elements (Al, Ca, Fe, Mg, S, Si and Ti) and trace elements
(Ba, Cr, Mn, Ni, Sr, V, Zn and Zr) in coal were determined. Various slurry preparations were evaluated
using two dispersants (glycerol and Triton X-100) and by varying the concentration of dispersants,
between 0.1% and 1.0% (v/v). The effect of initially solubilising the ground coal in N,N-dimethylformamide
(DMF) was investigated by varying the volume of DMF added. The effect of wet grinding with DMF was
investigated. Wet grinding with DMF was shown to drastically reduce particle sizes (50.0% < 0.28 lm and
90.0% < 6.17 lm) as compared to dry grinding (50.0% < 5.25 lm and 90.0% < 11.1 lm). The reduced particle
sizes and increased transport efficiency of the coal slurries led to improved analytical recoveries of
elements in the reference coal, SARM 18. The best analytical recoveries for all elements were achieved
using 0.1% Triton X-100 with 10.0% DMF. Results obtained by ICP-OES after wet grinding of the coal with
DMF, using 0.1% Triton X-100, also gave excellent recoveries (Al, 100%; Ca, 103%; Cr, 106%; Fe, 102%; Mg,
100%; Mn, 104%; Ni, 109%; Si, 102%; Ti, 95.0%; and V, 108%). The results obtained with 10.0% DMF and
0.1% Triton X-100 were in agreement with certified values for all selected elements according to paired
t-test at the 95.0% confidence level. Selected elements (Al, Ca, Fe, Mg, Mn, Si, Ti and V) were also analysed
with X-ray fluorescence for comparison with results obtained from ICP-OES. Analysis by ICP-OES of
microwave digested coal was also carried out. It is suggested that the DMF slurry technique could be used
for routine analysis of bituminous coals.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:tut/oai:encore.tut.ac.za:d1001696 |
| Date | 01 January 2009 |
| Creators | Mujuru, M, McCrindle, RI, Botha, BM, Ndibewu, PP |
| Publisher | Elsevier |
| Source Sets | South African National ETD Portal |
| Language | English |
| Detected Language | English |
| Type | Text |
| Format | |
| Rights | c2008 Elsevier Ltd. |
| Relation | Fuel |
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