Magnetic desulfurization is an attractive physical method of coal cleaning which has been studied for a quarter century. High‐frequency selective heating of coal to convert nonmagnetic pyrite to moderately magnetic pyrrhotite has been suggested to enhance separation. Despite predicted feasibility, some successes have only recently been attained. We report on the use of Mössbauer spectroscopy and magnetization to follow indirectly the amounts of inorganic sulfur in coal. We observe significant conversion (≳10%) to pyrrhotite by microwave treatment of coarse coal granules at 915 MHz and 2.45 GHz at power levels of a few kW for about 1 min. Analysis of phase distribution allows independent calculation of the inorganic desulfurization resulting from microwave treatment and magnetic separation.

Topics
Minerals, Chemical elements, Gemstones, Mossbauer spectroscopy
1.
“Coal Desulfurization‐Chemical and Physical Methods,” ACS Symposium Ser., Vol. 64, T. D. Wheelock, ed., (Am. Chem. Soc., Washington, 1977).
2.
I. S.
Jacobs
,
L. M.
Levinson
,
H. R.
Hart
, Jr.,
J. Appl. Phys.
49
,
1775
(
1978
).
Google Scholar
Crossref
Search ADS
 
3.
P. A.
Montano
,
Fuel
56
,
397
(
1977
);
Google Scholar
Crossref
Search ADS
 
L. M.
Levinson
 and
I. S.
Jacobs
,
Fuel
56
,
453
(
1977
); ,
Fuel
Google Scholar
Crossref
Search ADS
 
G. P.
Huffman
 and
F. E.
Hoggins
,
Fuel
5J7
,
592
(
1978
); ,
Fuel
Google Scholar
 
also one early paper,
J. F.
Lefelhocz
,
R. A.
Friedel
 and
T. P.
Kohman
,
Geochim. Cosmochim. Acta
31
,
2261
(
1967
).
Google Scholar
Crossref
Search ADS
 
4.
L. M. Levinson, Electric Power Res. Inst., Palo Alto, CA, Report EPRI FP‐1228, Oct. 1979.
5.
S. Siddiqui, German Patent No. 1,005,012, March 28, 1957.
6.
S. C. Trindade, PhD Thesis, Chem. Eng., MIT, 1973;
S. C.
Trindade
,
J. B.
Howard
,
H. H.
Kolm
 and
G. J.
Powers
,
Fuel
53
,
178
(
1974
).
Google Scholar
Crossref
Search ADS
 
7.
Proceedings of the Symposium on Magnetic Desulfurization of Coal, Auburn, Ala., March 23–25, 1976, IEEE Trans. Magnetics MAG‐12, 423–551 (1976).
8.
Coal Preparation Using Magnetic Separation, Electric Power Res. Inst., Palo Alto, CA, Report EPRI CS‐1517, vols. 1–5, July 1980.
9.
H.
Kolm
,
J.
Oberteuffer
 and
D.
Kelland
,
Sci. Am.
223
, No.
5
(Nov.)
46
(
1975
).
Google Scholar
Crossref
Search ADS
 
10.
S. Ergun and E. H. Bean, US Bureau of Mines, Reports of Investigation 7181 (1968).
11.
M. D. Hassialis, in “Handbook of Mineral Dressing: Ores and Industrial Minerals,” A. F. Taggert, ed., (John Wiley, N.Y., 1945) Sec. 13, Article 6, p. 13–33.
12.
H. A.
Fine
,
M.
Lowry
,
L. F.
Power
, and
G. H.
Geiger
,
IEEE Trans. Magnetics
,
MAG‐12
,
523
(
1976
).
Google Scholar
 
13.
M. D. Bluhm, G. E. Fanslow, S. R. Beck‐Montgomery, “Selective Magnetic Enhancement of Pyrite in Coal by Dielectric Heating,” Final Report, Oct. 1, 1978–Dec. 31, 1980, IS‐4766, UC90b, July 1981 (available from NTIS).
See also
G. E.
Fanslow
 et al.,
J. Microwave Power
15.
, (
3
)
187
(
1980
);
Google Scholar
Crossref
Search ADS
 
S. O.
Nelson
 et al.,
J. Microwave Power
15
(
4
),
277
(
1980
); ,
J. Microwave Power
Google Scholar
Crossref
Search ADS
 
D. D. Bluhm et al., AIP Conf. Proc., No. 70, p. 417 (1980).
14.
P. D. Zavitsanos, J. A. Golden, K. W. Bleiler and W. K. Kinkead, “Coal Desulfurization Using Microwave Energy” EPA Report 600/7‐78‐089 (June 1978).
15.
P. D. Zavitsanos, J. A. Golden, K. W. Bleiler, I. S. Jacobs and H. Thai, Report to EPA, Feb. 1981.
16.
I. S.
Jacobs
 and
P. D.
Zavitsanos
,
Bull. Am. Phys. Soc.
26
,
469
(
1981
).
Google Scholar
 
17.
See also Coal Age, Feb. 1981, p. 93.
18.
L. M.
Levinson
 and
D.
Treves
,
J. Phys. Chem. Solids
29
,
2227
(
1968
).
Google Scholar
Crossref
Search ADS
 
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© 1982 American Institute of Physics.
1982
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