United States Patent [19]
Kindig et a1.
[11]
[45]
4,175,924
Nov. 27, 1979
[75]
[73]
[21]
[22]
[51]
[52]
[58]
[56]
20 Claims, No Drawings
Raw coal is improved by reacting it with a metal containing
compound selected from the group consisting of
organic iron containing compounds which exert sufficient
vapor pressure, with iron as a component in the
vapor, so as to briiJ.g the iron into contact with the
impurity at the reaction temperature, organic iron containing
compounds in solution at the injection temperature,
solid organic iron containing compounds capable
ofbeing directly mixed in solid form at the mixing temperature
with the coal, and ferrous chloride, ferric chloride,
and alkyl aluminum compounds, in order to enhance
the magnetic susceptibility of certain impurities,
e.g., pyrite and ash-forming minerals contained in the
raw coal, thereby permitting the removal ofthese impurities
by magnetic means.
[54] TREATMENT OF COAL WITH METAL [57] ABSTRACf
CONTAINING COMPOUNDS
Inventors: James K. Kindig. Arvada; Ronald L.
Turner, Gol~en. both of t?IO.
Assignee: Hazen Research, Inc., Go14en, Colo.
Appl. No.: 767,352
Filed: Feb. 10, 1977
Int. CI.2 CI0L 9/10; ClOD 57/00.
U.S. CI 44/15 R; 201/17
Field of Search 44/1 R; 201117
References Cited
U.S. PATENT DOCUMENTS
3,938,966 2/1976 Kindig et aI 44/1 R
Primary Examiner-Carl Dees
Attorney. Agent. or Firm-Sheridan, Ross, FieldS &
McIntosh
SUMMARY OFTHEINVENTION
The magnetic susceptibility of pyrite and other impurities
in coal is selectively enhanced by treating the coal
containing pyrite and/or other impurities with one or
more metal containing compounds selected from the
2
enhancing the magnetic susceptibility of the pyrite or
other impurity. Coal particles alone are slightly diamagnetic
while pyrite and many other mineral impurities
are weakly paramagnetic; however, their paramagne-
5 tism has not been sufficient to economically effect a
separation from coal. However, effective beneficiation
of coals can be made if the magnetic susceptibility of
pyrite or other impurities is increased. For pyrite it has
been estimated that a sufficient increase in susceptibility
10 can be achieved by converting less than 0.1 percent of
pyrite in pyritic coal into ferromagnetic compounds of
iron ("Magnetic Separation of Pyrite from Coals," Bureau
of Mines Report ofInvestigations 7181, p.l).
In discussing the use of heat to enhance the paramag-
IS netism of pyrite it is stated in the above report (p.l) that
ferromagnetic compounds of. iron are not formed in
significant quantities at tempratures below 400' C., and
that such conversion occurs in sufficient quantities to
effect beneficiation only at temperatures greater than
500' C. As this is above the decomposition temperature
of coal, the use of heat to enhance the magnetic susceptibility
.of impurities does not appear feasible. Further,
other methods for enhancing the paramagnetism of
pyrite to permit its separation from coal have not been
encouraging.
U.S. Pat. No. 3,938,966 discloses a process for improving
coal wherein the raw coal is reacted with substantially
undecomposed iron .carbonyl which alters the
magnetic susceptibility of certain impurity components
contained in the raw coal, thereby permitting their
removal by low-intensity magnetic separators. This
process represents a noteworthy advance in the art, as
treating coal in accordance with this process may substantially
remove impurities such as pyrite, a primary
contributor to sulfur dioxide pollution problems. The
process of this patent, however, does not appear to
possess universal applicability with an equal degree of
success in that while many coals are substantially enhanced
by this treatment, certain other coals are not as
receptive.
Iron carbonyls, particularly iron pentacarbonyl, are
representative of an unusual class of compounds in
which the metal is present in the zero valance state. This
"zero valence iron" decomposition allows the iron to
selectively react with various impurities contained
within raw coal, while not affecting the coal itself.
There appear to be several bases for such an unusual
result, including the probability that active sites on the
impurity particles accelerate the decomposition of iron
carbonyl to metallic iron and carbon monoxide. Also it
is likely that iron carbonyl reacts at temperatures near
its decomposition temperature as if it were chemically
free metallic iron vapor, a very reactive reducing agent.
It has been discovered by the inventors of the present
application, however, that not only vaporized iron carbonyls
are beneficial in effecting removal ofimpurities
from raw coal, but that a wide variety of metal containing
compounds, most of which contain metals existing
in other than the zero valence state, can also be used on
various coals to effect such a removal by magnetic
separation.
4,175,924
1
TREATMENT OF COAL WITH METAL
CONTAINING COMPOUNDS
BACKGROUND OF THE INVENTION
1. Field of the Invention
The process of the present invention relates to the
improvement of the properties of coal, andis.classified
generally in the class relating to fuels and igniting devices.
2. The Prior Art
With the present world-wide emphasis on the energy
crisis and the rapidly diminishing sources of oil, increased
attention by both government and private organizations
is being given to coal as a source of energy,
especially for the generation of electricity. This country
has vast resources of coal for development as other
sources of energy diminish.
Depending upon. their origin, coals contain varying
amounts of iron. disulfide (iron disulfide is. hereinafter 20
referred to as pyrite whether crystallized as pyrite or
marcasite) from which sulfur dioxide is formed as a
combustion product when coal is burned.• This is a tremendous
disadvantage to the use of coal as an energy
source, particularly in view of the current emphasis on 2S
pollution controls as illustrated by present federal emission
control standards for sulfur dioxide. Illustrating the
enormity of the sulfur dioxide emission problem is the
fact that large transportation expenses are incurred by
coal users in transporting Western and European coal of 30
relatively low sulfur content long distances to supplant
available high sulfur-containing coals· in order to comply
with sulfur dioxide emission standards. At this time
there are not effective means available which are commercially
feasible for absorbing the large amounts of 35
sulfur dioxide emitted by the combustion .of. coal to
produce heat and electricity. One solution of the problem
is to separate the sulfur-bearing pyrite from the coal
before it is burned.
.. Coals also contain, depending upon their origin, vari- 40
ous amounts and kinds of minerals which form ash
when the coal is burned. The ash also is a disadvantage
to the use of coal as an energy source, since it contributes
no energy value during combustion. The ash causes
a dilution of the calorific value of the coal, and causes a 4S
waste disposal problem and a potential air pollution
problem.
The problem of separating pyrite and/or other impurities
from raw coal isnot new and a number of methods
have been extensively·tested over the years. Among 50
these are methods which employ the differencein specific
gravity between coal particles and the impurity
particles or differences in their surface, electrostatic,
chemical, or magnetic properties. For various reasons
difficulties are encountered in making an efficient sepa- 5S
ration of pyrite or other impurities from coal which has
been ground finely enough to substantially liberate impurity
particles from coal particles. In water systems
this difficulty is related to the slow settling rate of fme
particles, and in air systems to the large difference in 60
specific gravity between air and the particles. However,
for· magnetic separations the magnetic attraction force
acting on smallmagnetic particles is many times greater
than the oppOsing. force, which is usually. a hydraulic
drag and/or gravity force. 6S
For the separation of pyrite or other impurities from
raw coal the success of a magnetic process is dependent
upon some effective treatment process for selectively
4
more magnetic than pyrite. The following reaction
exemplifies this mechanism:
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 reactiori:
4,175,924
DESCRIPTION OF THE PREFERRED
EMBODIMENT
3
group consisting of organic iron containing compounds
which exert sufficient vapor pressure, with iron as a
component in the vapor, so as to bring the iron into
contact with the impurity at the reaction temperature,
organic iron containing compounds in solution at the 5
injection temperature, solid organic iron containing
compounds capable of being directly mixed in solid
form at the mixing temperature with the coal, and ferrous
chloride, ferric chloride, and alkyl aluminum compounds,
under suitable operating conditions. After the 10
coal is so treated, it is then passed through a magnetic
separator for removal of the affected impurities. Other mechanisms undoubtedly also contribute to the
enhancing of the magnetic susceptibility, and again this
is principally determined by the particular metal con15
taining compound or compounds employed and the
reaction conditions. It is to be understood that in view
The process of the present invention can be applied to of the disclosures herein presented, the selection of a
coals of universal origin, as long as the coal contains one given metal compound, along with the most desirable
or more impurities receptive to the metal treatment. reaction conditions to be employed with the given com-
The process employs a metal treatment in order to en· pound, cannot be itemized for each and every comhance
the magnetic susceptibility of an impurity. By 20 pound due to· the number of variables involved. Howselectively
enhancing this property of the impurity, ever, the proper selection will be apparent to one skilled
while not affecting the coal itself, a magnetic separation in the art with but a minimal amount of experimentamay
be conventionally accomplished to remove the tion, and it is sufficient to note that the improvement of
impurity from the coal. The coal is therefore left in a 25 the invention herein set forth relates to all of these commore
pure state, rendering it more suitable for combus- pounds.
tion. Many organic metal containing compounds possess
"Enhancing the magnetic susceptibility" of a particle the capability of enhancing the magnetic susceptibility
or an impurity as used herein is intended to be defined in of coal impurities, as long as the compound is adaptable
accordance with the following discussion. Every com- 30 so as to bring the metal in the compound into contact
pound of any type has a specifically defined magnetic with the impurity under conditions such as to cause an
susceptibility, which refers to the overall attraction of alteration of at least a portion of the surface of the imputhe
compound to a magnetic force. An alteration of the rity. Organic metal containing compounds capable of
surface characteristics will alter the magnetic suscepti- exerting sufficient vapor pressure, with the metal as a
bility. The metal treatment of the process alters the 35 component in the vapor, so as to bring the metal into
surface characteristics of an impurity in order to en- contact with the impurity at the reaction temperature
hance the magnetic susceptibility ofthe impurity. It is to are suitable, as well as other organic metal containing
be understood that the magnetic susceptibility of the compounds which can be dissolved and/or "dusted"
impurity is not actually changed, but the particle itself is (directly mixed with the coal) and brought into contact
changed, at least at its surface, resulting in a particle 40 with the impurity.
possessing a greater magnetic susceptibility than the Preferred compounds within the vapor pressure
original impurity. For convenience of discussion, this group are organic iron containing l;ompounds whIch
alteration is termed herein as "enhancing the magnetic exert a vapor pressure as described above. Preferably
susceptibility" of the· particle or impurity itself. these compounds exert a vapor pressure, with iron asa
The impurities with which the process of the present 45 component in the vapor, of at least about 0.5 millimeter~
invention may be utilized include those impurities of mercury, more preferably at least about 25 millime"
which react with one or more of the metal compounds ters of mercury, and most preferably at least about 50
hereinafter described to form a product possessing an millimeters of mercury at the reaction temperature.
enhanced magnetic susceptibility. Examples of such Examples of groupings which fall within this vapor
impurities include pyrite; ash-forming minerals, such as 50 pressure definition include ferrocene and its derivatives
clays and shales; and various sulfates, for example, cal- and ,B-diketone compounds of iron. Specific examples
cium sulfate and iron sulfate. For purposes of illustra- include ferrocene, dimethyl ferrocenedioate, l,l'-fertion
the discussion hereinafter refers to pyrite, but it is rocenedicarboxylic acid, ferric acetylacetonate, ferrous
to be understood that other suitable impurities may be acetylacetonate, acetyl ferrocene, ferrocene aldehyde,
effected in similar fashion. 55 ferrocene carboxylic acid, a-hydroxyethyl ferrocene,
Numerous metal containing compounds are suitable and l,l'-dihydroxymethyl ferrocene.
to impart this magnetic susceptibility. A number of Other organic compounds which may be utilized to
different mechanisms are believed to be involved in enhance the magnetic susceptibility include those
what is termed herein as the "treatment" and/or mag- \Vhich may be dissolved and brought into contact with
netic susceptibility enhancement "reaction" depending 60 the impurities. These compounds must have sufficient
upon the metal containing compound or compounds solubility so as to provide sufficient metal to contact the
and the reaction conditions employed. Some metal con- surface of the impurity. Preferably the solubility is at
taining compounds, with metals more magnetic than the least about I gram per liter, more preferably at least
impurities, principally iron, under certain conditions about 10 grams per liter, and most preferably at least
coat the impurity with the metal, thereby enhancing the 65 about 50 grams per liter at the injection temperature.
magnetic susceptibility of the impurity. Some metal The solvent must, of course, possess the capability of
containing compounds affect the pyrite by combining dissolving the organic compounds within the above set
with some of the pyrite sulfur to yield an iron sulfide forth concentrations, and preferably not create side
4,11§,924
The results of treating Lower Freeport coal, sized
14-mesh by 0, with vatious iron compounds vaporized
externally and then injected as a vapor into the reaction
chamber while the coal was heated to the maximum
temperature indicated are presented in Table 3. Samples
1-4 were. first pretreated with steam for one hour at
200· C. with 192 kilograms of water per metric ton of
coal. Samples 5 through 7 were first dried at a temperature
of 130· C. for 30· minutes prior to the treatment
with' the iron compound.
EXAMPLE 2
Several samples ofPittsburgh Seam coal sized 14mesh
by 0 were treated with various iron compounds
applied either by wetting the coal with a solution and
evaporating the solvent (S/E) prior to heating the coal,
or by directly mixing the iron compound as a powder
with the coal at room temperature (OM) prior to heating.
The results are presented below in Table 2.
EXAMPLE 3
EXAMPLES
EXAMPLE I
Samples of Pittsburgh Seam coal size~ 14-mesh by 0
were treated with different iron compounds in a nitrogen
atmosphere. The iron compounds were vaporized
externally and then injected asa vapor into the reaction
chamber as the coal was heated stepwise to the maximum
temperature. The. results along with the type and
amount of iron compound are given in Table 1.
6
temperature of major decomposition of the metal containing
compound under the reaction conditions such
that there is opportunity for the metal of the compound
to react with the impurity particles. Ifthe temperature
5 is above the decomposition temperature, the selectivity
of the process of enhancing the magnetic susceptibility
of one or more impurities without affecting the coal is
impaired. The alkyl aluminum compounds are not
bound by the requirement.
For efficient separations of pyrite from coal, the coal
should be crushed to such fineness that pyrite particles
are free, or nearly free, from the coal particles. The
required fineness depends upon. the size distribution of
the pyrite in the coal. A thorough treatment of the
subject for power plant coals is given in the article
entitled "Pyrite Size Distribution and Coal-Pyrite Particle
Association in Steam Coals," Bureau of Mines Report
of Investigation 7231. The requirement for pyrite
liberation applies to all types ofphysical separations and
so is not a disadvantage of this invention. Additionally,
present technology for coal-fired power plants generally
required pulverizing the coal to 60-90 percent
minus 200 mesh before burning.
Prior to treating the raw coal with a metal containing
compound, the coal can be. pretreated with heat or
steam or pretreated to remove elemental sulfur in order
to render the coal and impurities more receptive to the
magnetic enhancement reaction.. Methods of heat and
steam pretreatment can be found in copending application
Ser. No. 761,307, filed Jan. 21, 1977, and methods
for the removal of elemental sulfur can. be found in
copending application Ser. No. 764,390, filed Jan. 31,
1977.
5
reaction problems tending to detract from the effectiveness
of the process. Suitable solvents include; for example,
acetone, petroleum ether, naphtha, hexane, kerosene,
and benzene. This is!, of course, dependent upon
the particular metal compound being employed.
Groupings which fall within this solution definition
include the carboxylic acid salts of iron and ,8-diketone
compounds of iron. Specific examples include iron octoate,
iron naphthenate, iron stearate, ferric acetylacetonate,
and ferrous acetylacetonate. '., 10
Additionally, solid organic iron containing compounds
capable of being directly mixed with the coal in
solid form possess the capability of enhancing the magnetic
susceptibility of coal impurities. The compound
must be in solid fonn at the mixing temperature and be 15
of sufficiently fine particle size in order to be able to be
well dispersed throughout the coal. The particle size is
preferably smaller than about 20 mesh, more preferably
smaller than about 100 mesh, and most preferably 20
smaller than about 400 mesh. Compounds within this
grouping include ferrocene and its derivatives, iron salts
of organic acids, and ,8-diketone compounds of iron.
Specific examples include ferrousformate,l,l'-diacetyl
ferrocene, and 1,1'-dihydroxymethyl ferrocene. 25
Several other compounds are also suitable for enhancing
the magnetic susceptibility of various coal impurities
to the exclusion of coal. These compounds
include ferrous chloride, ferric chloride and. alkyl aluminum
compounds, such as triisobutyl aluminum. Fer- 30
ric chloride and ferrous chloride may be injected by the
direct mixing andlor solvent techniques as described
hereinabove. The alkyl aluminum compounds ate injected
either by vaporizing external to the reaction
vessel and allowing the vapor to pass over the heated 35
coal, or by spraying the alkyl compound .directly onto
the heated coal. A carrier gas may be used as a convenience
to help transfer the alkyl aluminum into the
reaction chamber, but is not inherently required.
The process, as it relates to the vaporizable compo- 40
nents described hereinabove, is applied by contacting
the raw coal which is liberated from pyrite or other
impurities with the metal containing compound under
conditions such that there is an insufficient dissociation
of the metal containing compound to cause substantial 45
deposition of metal on the coal particles. Th¢se conditions
are determined by the temperature,. the type of
metal containing compound, pressure, gas cOIriposition,
etc. Ordinarily, a gas ofthe metal containing compound
is heated to a temperature just below its decomposition 50
temperature under the reaction conditions. Various
types of available equipment can be used for contacting
the metal containing compound and coal, such as a
rotating kiln used as the reaction vessel with the metal 55
containing compound vapors carried into contact with
the tumbling contents of the kiln by a gas such as nitrogen.
The treatment is performed by contacting the coal
with the metal containing compound for a time of preferably
from about one tenth to about four hours, and 60
more preferably from about one half to about two
hours; at a temperature of preferably from about ISO· C.
to about 325· C. and more preferably from about 175·
C. to about 300· c., and at a concentration of preferably
from about 2 to about 75 kilograms per metric ton of 65
coal.
With respect to iron containing cOl11pounds, the process
must be carried out at a temperature below the
7
4,175,924
8
Table 1
Vapor Clean Coal Analysis
Sample Kg/Metric Maximum Time, Pressure Yield, Ash, Inorganic
Number Compound Ton Temp,'C. Hours mmHg Wt.% % Sulfur, %
I Ferrocene 16 265 I >760 97.6 20.7 1.76
2 Acetyl ferrocene 12 270 I >50 96.2 21.1 1.59
3 Ferrocene carboxylic acid 7 255 I >50 95.9 20.9 1.62
4 Ferrocene aldehyde 10.1 265 I >100 97.2 20.4 1.74
5 Dimethyl ferrocenedioate 12.3 250 I >10 95.7 20.2 1.54
6 Ferrous acetylacetonate 10.5 275 I >50 93.6 19.1 1.73
7 aHydroxyethyl ferrocene 15.1 300 I >50 89.1 18.7 1.62
8 Ferric acetylacetonate 11 275 2 >50 92.2 19.0 1.42
9 Ferric cyclohexane butyrate 11.2 300 2 >10 90.6 18.7 1.55
10 I,I'-Ferrocene dicarboxylic acid 12.4 300 I >1 70.8 18.7 1.24
11 Dimethyl ferrocenedioate 12.3 250 2 >10 95.7 20.2 1.54
12 Dimethyl ferrocenedioate 12.5 275 I >10 79.4 18.2 1.71
13 Ferrous acetylacetonate 10.5 175 I >.5 91.0 19.3 1.78
14 Ferric acetylacetonate 13.5 170 I >.5 90.9 18.4 1.76
Feed (No Treatment) 100.0 21.1 1.93
Table 2
Clean Coal Analysis
Sample Kg/Metric Method of Maximum Time, Yield, Ash, Inorganic
Number Compound Ton Application Temp, 'c. Hours Wt.% % Sulfur
I Ferric Chloride 68 OM 250 95.8 21.9 1.85
2 Ferrous Chloride 55 S/E 300 55.4 18.5 1.35
3 I,I'-Diacetyl ferrocene 16 OM 255 82.5 15.3 1.93
4 Ferrous acetylacetonate 16.5 S/E 300 90.0 17.7 1.90
5 Ferric acetylacetonate 16 SIB 295 70.1 13.9 1.48
Feed (Untreated) 100.1 21.1 1.93
Table 3
Vapor Clean Coal Analysis
Sample KglMetric Maximum Pressure Yield, Ash, Inorganic
Number Compound Ton Temp, ·C. mmHg Wt.% % Sulfur,
I Ferrocene 16 275 >760 74.1 23.8 1.41
2 Ferrocene carboxylic acid 7.9 275 >50 81.0 25.3 1.47
3 Acetylferrocene 13.0 275 >50 77.2 22.7 1.41
4 Dimethyl ferrocenedioate 15.0 275 >10 79.1 24.0 1.46
5 Ferrocene carboxylic acid 9.7 275 50 74.0 23.6 1.56
6 Dimethyl ferrocenedioate 15.6 275 >10 67.8 24.2 1.49
Feed (Untreated) 100.0 28.1 1.76
EXAMPLE 4
hour. The conditions and results are presented in Table
5.
EXAMPLE 6
A 75-gram sample of Pittsburgh Seam coal, sized
14-mesh by 0, was pretreated with steam for one hour at
200° C. with 192 kilograms of water per metric ton of
coal. Thereafter, it was treated with 5 milliliters of triisobutyl
aluminum which was slowly vaporized and
carried by 275 milliliters per minute of nitrogen into the
reaction chamber as the coal was heated to 250° C. and
maintained at this temperature for one hour. A blank
55 run was conducted on an identical sample of coal, with
the treatment gas consisting of nitrogen alone. A product
analysis of this blank run is not provided as essentially
none of this sample was enhanced in magnetic
susceptibility.
Table 4
EXAMPLE 5
Pittsburgh Seam coal, size 14-mesh by 0, was treated
with different iron compounds and either hydrogen at
200 milliliters per minute or carbon monoxide at 24
milliliters per minute for periods of time of about one
Samples of Lower Freeport coal, size 14-mesh by 0, 45
were treated with ferric chloride and ferric acetylacetonate
by dissolving these compounds in a volatile
solvent which was mixed with the coal and allowed to
evaporate prior to heating. Samples I and 2 were first
pretreated with steam at 200° C. for one hour with 192 50
kilograms of water per metric ton of coal. Sample 3 was
first dried at 130° C. for 30 minutes prior to being
treated with the iron compound.
15 min. @ Clean Coal Analysis
Sample Kg/Metric Maximum Yield, Ash, Inorganic
Number Compound Ton Temp, ·C. Wt.% % Sulfur, %
I Ferric Chloride 26.5 300 55.7 22.7 1.55
2 Ferric Acetylacetonate 16 285 75.1 22.4 1.31
3 Ferric Acetylacetonate 16.1 285 75.3 22.7 1.64
Feed (Untreated) 100.0 28.1 1.76
9
4,175,924
10
Table 5
Method Vapor
Kg.! of Pres- Mall. Clean Coal Analysis
Sample Metric Cotreatment Appli- sure, Temp., Yield, Ash, Inorganic
Number Compound TOil Gas cation mmHg 'Co Wt.% % Sulfur, %
I Hydroxyethyl ferrocene 17.2 H2 Inj. >50 300 88.1 18.7 1.01
2 Dimethyl ferrocenedioate 17.9 H2 Inj. >50 300 87.9 18.7 1.22
3 Dimethyl ferrocenedioate 15.0 CO Inj. >10 280 88.4 19.3 1.58
4 Ferric acetylacetonate 16 CO S/E >100 300 81.8 17.2 1.78
5 Ferric octoate 16.3 CO S/E >1 300 83.3 17.9 1.59
6 Ferric octoate 36.3 H2 SIE >1 275 46.0 9.2 0.69
7 Ferrous formate 32 H2 DM >1 250 92.2 20.8 1.42
8 Ferric chloride 68.9 H2 DM >50 275 86.7 21.3 1.30
9 Ferrous chloride 46.2 H2 DM >50 275 92.8 20.8 1.10
10 Ferrous acetylacetonate 16 H2 S/E >7.5 175 88.9 18.6 1.43
11 Ferric acety1acetonate 16 H2 SIE >100 300 45.7 13.1 1.23
12 Ferric benzoylacetonate 32 H2 S/E >5 275 87.7 17.6 1.25
13 Ferrocene 16 CO Inj. >760 280 85.6 19.3 1.62
14 Acetyl ferrocene 16 CO Inj. >50 280 89.8 19.2 1.55
15 Ferrocene carboxylic acid 8 CO Inj. >50 280 86.6 19.4 1.76
16 Ferrocene dicarboxylic acid 7.5 CO Inj. >1 280 87.5 19.4 1.55
Feed (Untreated) 100.0 21.1 1.93
Table 6
Yield Ash, Inorganic
Description Product Wt.% % Sulfur, % 25
Triisobutyl aluminum Clean coal 90.8 20.4 1.56
Blank Clean coal 99.2
Feed 20.3 1.93
ylic acid, a-hydroxyethyl ferrocene, and 1,1'-dihydroxymethyl
ferrocene.
6. The process. of claim 1 wherein the organic iron
containing compound is in solution at the injection temperature.
7. The process of claim 6 wherein the organic iron
containing compound has a solubility of at least about 1
30 gram per liter of solvent at the injection temperature.
8. The process of claim 6 wherein the organic iron
containing compound has a solubility of at least about
50 grams per liter of solvent at the injection temperature.
9. The process of claim 6 wherein the solvent is selected
from the group consisting of acetone, petroleum
ether, naphtha, kerosene, hexane, and benzene.
10. The process of claim 6 wherein the organic iron
containing compound is one or more members selected
from the group consisting of carboxylic acid salts of
iron and ,B-diketone compounds of iron.
11. The process of claim 10 wherein said organic iron
containing compound is a member selected from the
group consisting of iron octoate, iron naphthenate, iron
stearate, ferric acetylacetonate, and ferrous acetylacetonate.
12. The process of claim 1 wherein the metal containing
compound comprises one or more solid organic iron
containing compounds capable of being directly mixed
in solid form at the mixing temperature with the coal.
13. The process of claim 12 wherein the particle size
of said solid organic iron containing compound is less
than about 20 mesh.
14. The process of claim 12 wherein said organic iron
containing is one or more members selected from the
group consisting of ferrocene and its derivatives, iron
salts of organic acids, and ,B-diketone compounds of
iron.
15. The process of claim 12 wherein said organic iron
containing compound is selected from the group consisting
of. ferrous fonnate, 1, I'-diacetyl. ferrocene, and
I, I'-dihydroxymethyI ferrocene.
16. The process ofclaim 1 wherein the metal containing
compound is a member selected from the group
consisting of ferrous chloride, ferric chloride and alkyl
aluminum compounds.
17. The process of claim 16 wherein said alkyl aluminum
compound is triisobutyl aluminum.
What is claimed is:
1. A process for improving coal comprising treating
raw coal with a metal containing compound selected
from the group consisting of:
organic iron containing compounds which exert sufficient
vapor pressure, with iron as a component in 35
the vapor, so as to bring the iron into contact with
the impurity at the reaction temperature;
organic iron containing compounds in solution at the
injection temperature;
solid organic iron containing compounds capable of 40
being directly mixed in solid form at the mixing
temperature with the coal; and
ferrous chloride, ferric chloride, and alkyl aluminum
compounds; under conditions so as to enhance the
magnetic susceptibility of various impurity compo- 45
nents contained in the raw coal, thereby permitting
their removal by magnetic separation.
2. The process of claim 1 wherein the metal containing
compound comprises one or more organic iron
containing compounds which exert a vapor pressure, 50
with iron as a component in the vapor, of at least about
0.5 millimeters oflJlercury at the treatment temperature.
3. The process of claim 1 wherein the metal containing
compound comprises one or more organic iron 55
containing compounds which exert a vapor pressure,
with iron as a component in the vapor, of at least about
25 millimeters of mercury at the treatment temperature.
4. The process of claim 2 wherein the organic iron
containing compound is a member selected from the 60
group consisting of ferrocene, ferrocene derivatives,
and,B-diketone compounds of iron.
5. The process of claim 4 wherein said organic iron
containing compound comprises one or more members
selected from the group consisting of ferrocene, di- 65
methyl ferrocenedioate, 1,1'-ferrocenedicarboxylic
acid, ferric acetylacetonate, ferrous acetylacetonate,
acetyl ferrocene, ferrocene aldehyde, ferrocene carbox'"
'" '" '" '"
12
taining compound at a temperature of from about 150·
C. to about 3250 C.
20. The process of claim 1 wherein the treatment is
performed by contacting the coal with the metal conS
taining compound at a concentration of from about 2 to
about 75 kilograms of metal containing compound per
metric ton of coal.
4,175,924
11
18. The process of claim 1 wherein the treatment is
performed by contacting the coal with the metal con~
taining compound for a time of from about one-half to
about four hours.
19. The process of claim 1 wherein the treatment is
performed by contacting the coal with the metal con-
10
15
20
25
30
35
45
50
55
60
65