United States Patent [19]
Kindig et ale
[11]
[45]
4,098,584
Jul. 4, 1978
[54] REMOVAL OF IMPURITIES FROM COAL [56]
[75] Inventors: James K. Kindig, Arvada; Ronald L.
Turner, Golden, both of Colo.
[73] Assignee: Hazen Research, Inc., Golden, Colo.
References Cited
U.S. PATENT DOCUMENTS
2,726,148 12/1955 McKinley et al. 44/1 R
3,595,965 7/1971 Franz et aI 201117 X
3,938,966 2/1976 Kindig et aI 44/1 R
Primary Examiner-Carl F. Dees
Attorney. Agent. or Firm-Sheridan, Ross, Fields &
McIntosh
[21] Appl. No.: 767,659 [57] ABSTRACT
[51] Into Cl,2 CI0L 9/10; CIOB 57/00
[52] U.S. Q •........................................ 44/1 R; 201/17
[58] Field of Search 44/1 R; 201/17
[22] Filed: Feb. 10, 1977
The magnetic susceptibility of various impurities contained
within coal is increased by simultaneously cotreating
the coal with a metal containing compound and
a gas selected from the group consisting of hydrogen
and carbon monoxide.
32 Qaims, No Drawings
The process of the present invention entails simultaneously
cotreating raw coal with a metal containing
compound and hydrogen or carbon monoxide gas
under conditions such as to enhance the magnetic susceptibility
of certain impurities contained in raw coal,
thereby permitting removal of the affected impurities
by magnetic means.
4,098,584
1
REMOVAL OF IMPURITIES FROM COAL
BACKGROUND OF THE INVENTION
2
other impurity. Coal particles alone are slightly diamagnetic
while pyrite and many other mineral impurities
are weakly paramagnetic; however, their paramagnetism
has not been sufficient to economically effect a
I. Field ofthe Invention 5 separation from coal. However, effective beneficiation
The process of the present invention relates to the of coals can be made if the magnetic susceptibility of
improvement of the properties of coal, and is classified pyrite or other impurities is increased. For pyrite it has
generally in the class relating to fuels and igniting de- been estimated that a sufficient increase in susceptibility
vi~The Prior Art 10 can be achieved by converting less than 0.1 percent of
With the present world-wide emphasis on the energy pyrite in pyritic coal into ferromagnetic compounds of
crisis and the rapidly diminishing sources of oil, in- iron. ("Magnetic Separation of Pyrite from Coals,"
creased attention by both government and private orga- Burea~ of ~es Report of Investigations 7181, p.I.)
nizations is being given to coal as a source of energy, ~ dlSCUSS~g t.h~ use of~eat to enhance the paramagespecially
for the generation ofelectricity. This country 15 netism ofpynte It 18 stated m the above report (p.l) that
has vast resources of coal for development as other ferromagnetic compounds of iron are not formed in
sources of energy diminish. significant quantities at temperatures below 400° C, and
Depending upon their origin, coals contain varying that such conversion occurs in sufficient quantities to
amounts of iron disulfide (iron disulfide is hereinafter effect beneficiation only at temperatures greater than
referred to as pyrite whether crystallized as pyrite or 20 500° C. As this is above the decomposition temperature
marcasite) from which sulfur dioxide is formed as a of coal, the use ofheat to enhance the magnetic suscepcombustion
product when coal is burned. This is a tre- tibility ofimpurities does not appear feasible. Further,
mendous disadvantage to the use of coal as an energy other methods for enhancing the paramagnetism of
source, particularly in view of the current emphasis on pyrite to permit its separation from coal have not been
pollution controls as illustrated by present federal emis- 25 encouraging.
sion ~ntrol standards fo~ sU;lfur di~xi.de. mustra~g the The same report (p.6) also investigated the effect of
enormity of the sulfur dio.lOde emtSSlon pr~blem 18 the heat treatment with various gases, e.g., hydrogen, carfact
that large transportation expenses are mcurred by bon monoxide carbon dioxide nitrogen concluding
coal ~ in transporting Western and ~uropean coals that none of the treatments couid be con~plated for
of relativ~ly 10": sulfur content .l~ng distan~ to sup- 30 any practical process because the residence time of the
plant available high sulfur-conta1ning coals m order to .,,
1 'th ulfur di'd .. tandards At this treatments was excessive. The only Significant reduccomp
y WI s OlO e emtSSlon s . ti f ulfur hi h bl . Id ed .
time there are no effective means available which are on 0 s w c gave a r~na .e yIe ~urr, m
commercially feasible for absorbing the large amounts a hydrogen atmosphere at 300 C WI~ a r~ldence time
of sulfur dioxide emitted by the combustion of coal to 35 of five hours. It was furth~r stated m this repo~ that
product heat and electricity. One solution to the prob- oth~r meth~ ~or enhan~mg the paramagnetiSm of
lem is to separate the sulfur-bearing pyrite from the coal pynte to permit Its separation from coal have not been
before it is burned. encouraging.
Coals also contain, depending upon their origin, vari- U.S. Pat. No. 3,938,966 discloses a process for imous
amounts and kinds of minerals which form ash 40 proving coal wherein the raw coal is reacted with subwhen
the coal is burned. The ash also is a disadvantage stantially undecomposed iron carbonyl which alters the
to the use of coal as an energy source, since it contrib- magnetic susceptibility of certain impurity components
utes no energy value during combustion. The ash causes contained in the raw coal, thereby permitting their
a dilution ofthe calorific value ofthe coal, and causes a removal by low-intensity magnetic separators. This
waste disposal problem and a potential air pollution 45 process represents a noteworthy advance in the art, as
problem. .. . treating coal in accordance with this process may sub-
. !he problem of ~aratingpynte and/or other ImpU- stantially remove impurities such as pyrite, a primary
nt!es from raw co~ 18 not new and a number ofmethods contributor to sulfur dioxide pollution problems. The
have been extenslvel~ tested over th~ years. ~ong process of this patent, however, does not appear to
~ese are ~ethods which emplo~ the differen~m s~- SO possess universal applicability with an equal degree of
cific. graVity ~tween ~al p~cles and the ImPun,ty success in that while many coals are substantially enparti<:
les or differen~ m th~ surface, ~lectrostatic, hanced by this treatment certain other coals are not as
chemIcal, or magnetic properties. For VariOUS reasons . , ' .
difficueltsi' are encounteredm' making an effCi'1ent sepa- receptive. Itlihas .beenhdaiscovered.by the mve.ntors ofthe
ration ofpyrite or other impurities from coal which has 55 preset,tt. app cation t t cotreating coal With a metal
been groundfmely enough to substantially liberate im- ~nta1ning compo~d and h~~rogen or c~bon monoxpurity
particles from coal particles. In water systems Ide gas under .VariOUS conditiOns as he!emafter presthis
difficulty is related to the slow settling rate of fine ented sUbs~tially enhances the effectiveness of the
particles, and in air systems to· the large difference in process of this patent.
specific gravity between air and the particles. However, 60 SUMMARY OF THE INVENTION
for magnetic separations the magnetic attraction force
acting on small magnetic particles is many times greater
than the opposing force, which is usually a hydraulic
drag and/or gravity force.
For the separation of pyrite or other impurities from 65
raw coal the success of a magnetic process is dependent
upon some effective treatment process for selectively
enhancing the magnetic susceptl'bility of the pyrite or
In similar fashion, U.S. Pat. No. 3,938,966 and the
reaction mechanisms illustrated therein with respect to
Similarly ash, such as Fe203, may react with a metal
to form a more strongly magnetic compound, as for
example, in accordance with the following reaction:
4,098,584
3
DESCRIPTION OF THE PREFERRED
EMBODIMENT
6M + 7FeS2 -> Fe,SB + 6MS
4
pyrite and iron pentacarbonyl present viable techniques
for enhancing the magnetic susceptibilities of impurities.
The process ofthe present invention can be applied to Other mechanisms undoubtedly also contribute to the
coals ofuniversal origin, as long as the coal contains one 5 enhancing of the magnetic susceptibility, and again this
or more impurities receptive to the described treatment. is principally determined by the particular metal con-
The process employs a metal containing compound and taining compound or compounds employed and the
a gas cotreatment in order to enhance the magnetic reaction conditions. It is to be understood that in view
susceptibility of an impurity. By selectively enhancing of the disclosures herein presented, the selection of a
this property of the impurity, while not affecting the 10 given metal compound and gas along with the most
coal itself, a magnetic separation may be conventionally desirable reaction conditions to be employed with the
accomplished to remove the impurity from the coal. given metal compound and gas cannot be itemized for
The coal is therefore left in a more pure state, rendering each and every combination due to the number of variit
more suitable for combustion. abIes involved. However, the proper selection will be
"Enhancing the magnetic susceptibility" of a particle 15 apparent to one skilled in the art with but a minimal
or an impurity as used herein is intended to be dermed in amount of experimentation, and it is sufficient to note
accordance with the following discussion. Every com- that the improvement of the invention herein set forth
pound ?~ ~y typ~ has a specifically defined ma~etic relates to all of these compounds.
susceptibilIty, which refers to the overall attraction of M . . +n:_:_ d the
h d . ti A al . f h any orgamc Iron COnL<U.llll1g compoun s possess
t e compoun to a magnetIC orce. n teratlon 0 t e 20 bilit f nh . th f fbilit f
surface characteristics will alter the magnetic suscepti- capa. Y? e ancmg e magne lC s~cep 1 y 0
bility. The metal and gas cotreatment of the basic pro- coallm~unties,.as lo~g as the compo~d 18 adaptable.so
cess alters the surface characteristics of an impurity in as t<;> brm~ the Iron m t~e. compound mto contact WIth
order to enhance the magnetic susceptibility of the th~ lmpunty under CO~dltl0ns such as to cause. an al~erimpurity.
It is to be understood that the magnetic sus- 25 ation ~f ~t least a P?~lOn of the surface ofthe lmp~ty.
ceptibility of the impurity is not actually changed, but Orgm;nc Iron containing co~po~ds capable of exert~g
the particle itself is changed, at least at its surface, re- suffiCIent vapor press~e, wl~h Ir~n as a compo~ent m
suIting in a particle possessing a greater magnetic sus- !he vapor, so as to b~g the Iron mto contact. WIth the
ceptibility than the original impurity. For convenience lmpunty at the re~C!10n temp~r~ture are swtable,. as
of discussion, this alteration is termed herein as "en- 30 well as other orgamc Iron containing compounds which
hancing the magnetic susceptibility" of the particle or can be dissolved and/or "dusted" and brought into
impurity itself. contact with the impurity.
The impurities with which the process of the present Preferred compounds within the vapor pressure
invention may be utilized include those impurities group are those which exert a vapor pressure, with iron
which react with one or more of the metal containing 35 as a component in the vapor, of at least about 10 millicompounds
and gases hereinafter described to form a meters of mercury, more preferably at least about 25
product possessing an enhanced magnetic susceptibility. millimeters of mercury, and most preferably at least
Examples of such impurities include pyrite; ash-forming about 50 millimeters of mercury at the reaction temperminerals,
such as clays and shales; and various sulfates, ature. Examples of groupings which fall within this
for example, calcium sulfate and iron sulfate. For pur- 40 vapor pressure defInition include ferrocene and its deposes
of illustration the discussion hereinafter often rivatives and ,B-diketone compounds of iron. Specific
refers to pyrite, but it is to be understood that all suit- examples include ferrocene, dimethyl ferrocenedioate,
able impurities are affected in similar fashion. 1,I'-ferrocenedicarboxylic acid, ferric acetylacetonate,
Numerous metal containing compounds are suitable and ferrous acetylacetonate.
t<? impart this ~agnetic susc.eptibility. A. number ?f 45 Other organic compounds which may be utilized to
dIfferent mechamsms are beheved to be mvolved m enhance the magnetic susceptibility include those
what is termed herein as the "treatment" and/or mag- which may be dissolved and brought into contact with
netic susceptibility e~~cement "reaction" depending the impurities. These compounds must have sufficient
upon the m~tal con~g compound or compounds solubility so as to provide sufficient metal to contact the
~d.the reactIon conW:tl0ns employed. Some ~etal con- 50 surface of the impurity. Preferably the solubility is at
~~~omp0.un~s,WIt~ metals more ma~etic th~ the least about 1 gram per liter, more preferably at least
lmpunti~, P~CIP~y Iron, under certain con~ltl0ns about 10 grams per liter, and most preferably at least
coat th,,: lmpunty ~t~ the metal,. there?y enhancmg the about 50 grams per liter at injection temperature. The
magn~t!c susceptibility of the lmPw:'-ty. Some ~~tal solvent must, of course, possess the capability of disc~
ntaining compound~ affect the p~te by. combmmg 55 solving organic compounds within the above set forth
WIth some of.the pynte s~fur to YIeld an. Iron su1f!.de concentrations, and preferably not create side reaction
more ~agnet~c than pynte. The followmg reaction problems tending to detract from the effectiveness of
exemplif1es this mechamsm: the process. Suitable solvents include, for example,
acetone, petroleum ether, naphtha, hexane, and ben60
zene; but this is, of course, dependent upon the particular
metal compound being employed.
A grouping which falls within this solution defInition
includes the carboxylic acid salts of iron; and specific
examples include iron octoate, iron naphthenate and
65 iron stearate.
Additionally, solid organic iron containing compounds
capable of being directly mixed with the coal in
solid form possess the capability of enhancing the magEXAMPLES
4,098,584
5 6
netic susceptibility of coal impurities. The compound most preferably at least about 10 liters per kilogram of
must be in solid form at the treatment temperature and coal.
be of sufficiently fine particle size in order to be able to The preferred parameters are dependent upon the
be well dispersed throughout the coal. The particle size specific impurities being treated, the specific comis
preferably smaller than about 2Q-mesh, more prefera- 5 pounds employed as the treating agent, and other facbly
smaller than about l00-mesh, and most preferably tors. Hence, some experimentation to determine the
smaller than about 400-mesh. Compounds within this optimum conditions for each specific system is pregrouping
include ferrocene and its derivatives, iron salts ferred. Generally, the cotreatment will be carried out
of organic acids, and l3-diketone compounds of iron. within a temperature range of from about 100· to about
Specific examples include ferrous formate, I, I'-diacetyl 10 400· C, more preferably from about 200· to about 350·
ferrocene, and 1,1'-dihydroxymethyl ferrocene. C, and most preferably from about 240· to about 300· C;
Various inorganic compounds are also capable of for a time ofpreferably at least about 0.1, more preferaproducing
an enhanced magnetic susceptiQility. Pre- bly at least about 0.25, and most preferably at least
ferred inorganic compounds include metal carbonyls, about 0.5 hours; with from about 1 to about 80, more
including, for example, iron, nickel, cobalt, molybde- 15 preferably from about 2 to about 50, and most preferanum,
tungsten, and chromium carbonyls and derivatives bly from about 5 to about 30 kilograms ofmetal containof
these compounds. Iron carbonyl is a preferred car- ing compound per metric ton of coal.
bonyl for imparting this magnetic susceptibility, partic- For efficient separations of pyrite from coal, the coal
ularly iron pentacarbonyl, iron dodecacarbonyl, and should be crushed to such fineness that pyrite particles
iron nonacarbonyl. 20 are free, or nearly free, from the coal particles. The
The most preferred metal containing compound ca- required fineness depends upon the size distribution of
pable of enhancing the magnetic susceptibility is iron the pyrite in the coal. A thorough treatment of the
pentacarbonyl.The process is applied by contacting the subject for power plant coals is given in the article
raw coal which is liberated from pyrite or other impuri- entitled "Pyrite Size Distribution and Coal-Pyrite Partities
with iron carbonyl under conditions such that there 25 cle Association in Steam Coals," Bureau of Mines Reis
an insufficient dissociation of carbonyl into metal and port of Investigation 7231. The requirement for pyrite
carbon monoxide to cause substantial deposition of liberation applies to all types ofphysical separations and
metal on the coal particles. These conditions are deter- so is not a disadvantage of this invention. Additionally,
mined by the temperature, the type of carbonyl, pres- present technology for coal-fired power plants genersure,
gas composition, etc. Ordinarily, the carbonyl gas 30 ally requires pulverizing the coal to 60-90 percent
is heated to a temperature just below its decomposition minus 200 mesh before burning.
temperature under the reaction conditions. Various Prior to subjecting the coal to this cotreatment with a
types of available equipment can be used for contacting metal containing compound and gas to enhance the
the iron carbonyl and coal, such as a rotating kiln used magnetic susceptibility ofthe coal, the coal can undergo
as the reaction vessel with iron carbonyl vapors carried 35 pretreatment by heat or steam or pretreatment to reinto
contact with the tumbling contents of the kiln by a move at least a portion ofthe elemental sulfur contained
gas such as nitrogen, which is inert to the reaction pro- within the raw coal or any other pretreatment which
cess. will enhance the magnetic susceptibility of the impuri-
When carbonyl is used as the magnetic susceptibility ties contained within the coal. Such pretreatments are
enhancement reactant, the process must be carried out 40 discussed in copending applications Ser. No. 761,307,
at a temperature below the temperature of major de- med Jan. 21, 1977, and Ser. No. 764,390, med Jan. 31,
composition of the carbonyl under the reaction condi- 1977.
tions so that there is opportunity for the iron of the
carbonyl to react with the pyrite particles. If the temperature
is allowed to rise above the decomposition 45 In each of the examples, the coal sample was sepatemperature,
the selectivity of the process of enhancing rated in a magnetic separator following the described
the magnetic susceptibility of one or more impurities treatment to give a non-magnetic clean coal fraction
without affecting the coal is impaired. and a magnetic refuse fraction.
Most preferably the iron pentacarbonyl treatment is The methods ofapplication as given in the Tables are
performed by contacting the coal with the carbonyl for 50 defined as follows:
a time of from about one-half to about four hours at a DM: The compound was directly mixed with coal,
temperature of from about 150· to about 200· C and a which was then heated stepwise to operating temperacarbonyl
concentration of from about 2 to about 16 ture;
kilograms per metric ton of coal. SIB: The compound was dissolved in suitable sol-
The improvement of the process of the invention 55 vent, mixed· with coal, and then dried in a stream of
concerns treating the coal with a metal containing com- nitrogen. The coal was then heated stepwise to operatpound
as hereinabove discussed, while simultaneously ing temperature.
treating the coal with a gas selected from the group Inj: The coal was heated stepwise to the maximum
consisting of hydrogen and carbon monoxide. These temperature, while the compound was vaporized extergases
in and of themselves have no appreciable effect 60 nally and injected as vapor into the reaction chamber.
upon the magnetic susceptibility of the coal impurities; EXAMPLE 1 .
however, they significantly improve the results obtained
over the metal containing compound treatments A seriesaf 75 gram samples of Pittsburgh Seam Coal,
in the absence of the gases. sized to 14-mesh by 0 and having no pretreatments, was
The type and amount of gas will depend to some 65 treated with various iron compounds as indicated in
extent upon the metal containing compound being used. Table 1. As Table 1 further indicates, each iron com-
Generally, the gas will be employed at a rate ofprefera- pound was employed alternately with hydrogen (200
bly at least about 1, more preferably at least about 5, and milliliters per minute) and nitrogen, the nitrogen simply
4,098,584
7
serving as an inert carrier. The nitrogen samples therefore
indicate the effect ofthe iron containing compound
alone on the impurities analyzed and reported.
EXAMPLE 2
A series of comparative samples were made on Pitts-
8
cotreated with the indicated iron compound and gas in
one test and the respective iron compound alone in
another test. The coal in Sample I was steam pretreated
with 192 kilograms of water per metric ton of coal for
5 one hour at 200· C. The coal of Samples 2-6 received
no pretreatment.
Table 1
Iron
Containing Method Clean Coal Analysis
Sam~ Iron Cotreating Compound of Appli. Maximum Yield, Ash, Pyritic
Num r Compound Gas KglMetric Ton cation Temp,'C Wt.% % Sulfur, %
I Iron gl) Formate ~ 32 DM 250 92.2 20.8 1.42
2 Iron I) Formate 32 DM 250 97.9 20.5 1.96
3 Iron II) Octoate HZ 36.3 SIB 275 46.0 9.2 0.69
4 Iron (III) Octoate ~ 32 SIB 275 85.9 19.3 1.99
5 Iron (III) Chloride ~ 68.8 DM 275 86.7 21.3 1.30
6 Iron (III) Chloride 68.1 DM 250 95.8 21.9 1.85
7 Iron (II) Chloride HZ 46.2 DM 275 92.8 20.8 1.10
8 Iron &B Chloride ~ 49.3 DM 260 98.9
9 Iron Acetylacetonate ~ 16 SIB 275 88.9 18.7 1.43
10 Iron (II) Acetylacetonate 16.7 SIB 300 90.0 17.7 1.90
11 Iron (Iill Acetylacetonate HZ 16 SIB 300 45.7 13.1 1.23
12 Iron (I Acetylacetonate ~ 16 SIB 295 70.1 13.9 1.48
13 Iron (III) Benzoylacetonate ~ 32 SIB 275 87.7 17.6 1.25
14 Iron (III) Benzoylacetonate 32 SIB 275 92.0 2Q.4 2.12
15 None ~ 300 98.7
16 None Z 300 99.2
Table 2
Sample
Number
1
2
3
4
5
67
8
9
10
11
12
Iron
Compound
Ferrocene
Ferrocene
Acetyl ferrocene
Acetyl Ferrocene
Ferrocene carboxylic acid
Ferrocene carboxylic acid
1,1'·Ferrocene dicarboxylic acid
l,l'-Ferrocene dicarboxylic acid
Dimethyl ferrocenedioate
Dimethyl ferrocenedioate
None
None
Cotreating
Gas
Iron
Containing
Compound
KglMetric Ton
16
16
16
12
87
7.5
6
15.0
12.3
Maximum
Temp,'C
280
265
280
270
280
255
280
275
280
250
300
300
Clean Coal Analysis
Yield, Ash, Pyritic
Wt. % % Sulfur, %
85.6 19.3 1.62
97.6 20.7 1.76
89.8 19.2 1.55
96.2 21.1 1.59
86.6 19.4 1.76
95.9 20.9 1.62
87.5 19.4 1.55
94.9 21.3 2.00
88.4 19.3 1.58
95.7 20.2 1.54
99.3
99.2
Table 3
Iron
Containing Maximum
Sample Gas Cotreatment Compound Method of Temp. Time, Yield. Ash, Inorganic
Number Compound Gas KglMetric Ton Application 'c Hours Wt.% % S,%
1 Iron carbonyl Hz-15 mlImin 16 Inj. 170 1 77.3 12.5 0.58
None 16 Inj. 170 1 86.8 12.4 0.65
2 a-Hydroxyethyl ferrocene None 15.3' Inj. 250 1 97.8 21.1 2.14
Hr 200 mlImin 17.2 Inj. 300 2 88.1 18.7 1.01
3 Dimethyl ferrocenedioate None 12.3 Inj. 250 1 95.7 20.2 1.S4
Hz-200 mlImin 19.7 Inj. 300 2 87.9 18.7 1.22
4 None None 300 1 99.2
None Hr 200 mlImin 300 2 98.7
5 Iron (III) Octoate None 32 SIB 275 1 85.9 19.3 1.99
Iron (III) Octoate 00-25 mlImin 16.3 SIB 300 1 83.3 17.9 1.59
6 None None 300 1 99.2
None CQ-25 mlImin 300 1 99.3
Feed 100.0 21.1 1.93
burgh Seam Coal, sized 14-mesh by 0, having no pre- 55
treatment, the tests comprising alternately treating the
coal samples with various volatile ferrocene compounds
in a carbon monoxide atmosphere and a nitrogen
atmosphere. In each sample, the ferrocene compound
was vaporized and then injected as a vapor into 60
the reaction chamber as the coal was heated stepwise to
the maximum temperature indicated in Table 2. The
operating conditions and results are presented in Table
2.
EXAMPLE 3
Table 3 presents a series of samples of Pittsburgh
Seam coal, size 14-mesh by 0, each sample having been
65
What is claimed is:
1. In a process for improving coal wherein the coal is
treated with a metal containing compound in order to
enhance the magnetic susceptibility of certain impurity
components contained in the raw coal permitting their
removal by magnetic separation, the improvement comprising:
treating the coal with a gas selected from the group
consisting of hydrogen and carbon monoxide during
the metal containing compound treatment.
2. The process of claim 1 wherein the gas is hydrogen.
4,098,584
9 ro
3. The process of claim 1 wherein the gas is carbon 20. The process of claim 12 wherein the iron commonoxide.
pound is. a simple iron salt of a monobasic or dibasic
4. The process of claim 1 wherein the metal contain- organic acid.
ing compound and gas treatment is conducted at a tern- 21. The process of claim 20 wherein the iron salt of a
perature of at least about 100· C for at least 0.1 hours. 5 monobasic organic acid is iron formate.
5. The process of claim 1 wherein the metal contain- 22. The process of claim 12 wherein the iron coming
compound is employed in an amount of from about pound is a p-diketone.
1 to about 80 kilograms per metric ton of coal. 23. The process of claim 22 wherein the p-diketone
6. The process ofclaim 1 wherein the gas is employed iron compound is selected from the group consisting of
at a rate of at least about 1 liter per kilogram of coal. 10 ferric benzoylacetonate, ferric acetylacetonate and fer-
7. The process of claim 1 wherein the impurities en- rous acetylacetonate.
.hanced comprise pyrite. 24. The process of claim 12 wherein the iron com-
8. The process of claim 1 wherein the impurities en- pound is an iron salt of a carboxylic acid.
haneed comprise ash-forming minerals. 25. The process of claim 24 wherein the iron salt of a
9. The process of claim 1 wherein the metal contain- IS carboxylic acid is a ferric octoate.
ing compound comprises a substantially undecomposed 26. The process of claim 12 wherein the iron comcarbonyl
selected from the group consisting of iron pound is a hydroxyalkyl derivative of ferrocene.
carbonyl, nickel carbonyl, cobalt carbonyl, molybde- 27. The process of claim 12 wherein the iron containnum
carbonyl, tungsten carbonyl, chromium carbonyl, .ing compound comprises ferrous chloride.
and derivatives of these carbonyls. 20 28. The process of claim 12 wherein the iron contain-
10. The process of claim 9 wherein the carbonyl is ing compound comprises ferric chloride.
iron carbonyl. 29. The process ofclaim 26 wherein the hydroxyalkyl
11. The process of claim 9 wherein the iron carbonyl derivative of ferrocene is an a-hydroxyethyl ferrocene.
comprises iron pentacarbonyl. 30. A process for beneficiating coal, including reduc-
12. The process ofclaim 1 wherein the metal contain- 25 ing sulfur and ash, increasing calorific value, and iming
compound is an iron containing compound. proving other properties, which comprises contacting a
13. The process of claim 12 wherein the iron com- coal which contains impurities, such as pyrite or marcapound
is an organic iron containing compound. site or other ash-forming minerals, which are substan-
14. The process of claim 13 wherein the organic iron tially liberated from the coal particles, with an iron
containing compound is capable of exerting sufficient 30 carbonyl and a member selected from the group consistvapor
pressure, with iron as a component in the vapor, ing of hydrogen and carbon monoxide under reaction
so as to bring the iron into contact with the impurity at conditions which substantially preclude the general
the reaction temperature. thermal dissociation of the carbonyl into iron and carlS.
The process of claim 14 wherein the vapor pres- bon monoxide, in order to increase the apparent magsure
of the organic iron containing compound is at least 35 netic susceptibility of the impurities so that a magnetic
about 10 millimeters of mercury at the reaction temper- separation between the coal and impurities may be efature.
fected.
16. The process ofclaim 13 wherein said organic iron 31. The process of claim 30 wherein the cotreatment
containing compound is selected from the group con- gas comprises hydrogen.
sisting of ferrocene, ferrocene derivatives, and p-dike- 40 32. A process for beneficiating coal, including reductone
compounds of iron. ing sulfur and ash, increasing calorific value, and im-
17. The process of claim 12 wherein the iron com- proving other properties, which comprises contacting a
pound is selected from the group consisting of ferro- coal which contains impurities, such as pyrite or marcacene,
dimethyl ferrocenedioate, l,l'-ferrocenedicar- site or other ash-forming minerals, which are substanboxylic
acid, ferric benzoylacetonate, ferric acetylac- 45 tially liberated from the coal particles, with iron octoate
etonate, ferrous acetylacetonate, ferric octoate, a- and a member selected from the group consisting of
hydroxyethyl ferrocene, and ferrous formate. hydrogen and a carbon monoxide under reaction condi-
18. The process of claim 12 wherein the iron com- tions which substantially preclude the general thermal
pound is an ester of a ferrocene carboxylic acid deriva- dissociation of the carbonyl into iron and carbon montive.
50 oxide, in order· to increase the apparent magnetic sus-
19. The process of claim 18 wherein the ester of a ceptibility of the impurities so that a magnetic separaferrocene
carboxylic acid derivative is dimethyl ferro- tion between the coal and impurities may be effected.
cenedioate. • • • • •
55
60
65