4,098,584 Removal of impurities from coal

Patent Number/Link:

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

REMOVAL OF IMPURITIES FROM COAL

BACKGROUND OF THE INVENTION

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

DESCRIPTION OF THE PREFERRED

EMBODIMENT

6M + 7FeS2 -> Fe,SB + 6MS

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

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-

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

Iron

Compound

Ferrocene

Acetyl ferrocene

Acetyl Ferrocene

Ferrocene carboxylic acid

1,1'·Ferrocene dicarboxylic acid

l,l'-Ferrocene dicarboxylic acid

Dimethyl ferrocenedioate

None

Cotreating

Gas

Iron

Containing

Compound

KglMetric Ton

7.5

15.0

12.3

Maximum

Temp,'C

280

265

280

270

280

255

280

275

280

250

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

EXAMPLE 3

Table 3 presents a series of samples of Pittsburgh

Seam coal, size 14-mesh by 0, each sample having been

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. • • • • •