CA1198704A - Agglomeration type coal recovery processes - Google Patents
Agglomeration type coal recovery processesInfo
- Publication number
- CA1198704A CA1198704A CA000393881A CA393881A CA1198704A CA 1198704 A CA1198704 A CA 1198704A CA 000393881 A CA000393881 A CA 000393881A CA 393881 A CA393881 A CA 393881A CA 1198704 A CA1198704 A CA 1198704A
- Authority
- CA
- Canada
- Prior art keywords
- coal
- particles
- mineral matter
- composite
- agglomerates
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B03—SEPARATION OF SOLID MATERIALS USING LIQUIDS OR USING PNEUMATIC TABLES OR JIGS; MAGNETIC OR ELECTROSTATIC SEPARATION OF SOLID MATERIALS FROM SOLID MATERIALS OR FLUIDS; SEPARATION BY HIGH-VOLTAGE ELECTRIC FIELDS
- B03B—SEPARATING SOLID MATERIALS USING LIQUIDS OR USING PNEUMATIC TABLES OR JIGS
- B03B1/00—Conditioning for facilitating separation by altering physical properties of the matter to be treated
- B03B1/04—Conditioning for facilitating separation by altering physical properties of the matter to be treated by additives
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B03—SEPARATION OF SOLID MATERIALS USING LIQUIDS OR USING PNEUMATIC TABLES OR JIGS; MAGNETIC OR ELECTROSTATIC SEPARATION OF SOLID MATERIALS FROM SOLID MATERIALS OR FLUIDS; SEPARATION BY HIGH-VOLTAGE ELECTRIC FIELDS
- B03B—SEPARATING SOLID MATERIALS USING LIQUIDS OR USING PNEUMATIC TABLES OR JIGS
- B03B9/00—General arrangement of separating plant, e.g. flow sheets
- B03B9/005—General arrangement of separating plant, e.g. flow sheets specially adapted for coal
-
- C—CHEMISTRY; METALLURGY
- C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
- C10L—FUELS NOT OTHERWISE PROVIDED FOR; NATURAL GAS; SYNTHETIC NATURAL GAS OBTAINED BY PROCESSES NOT COVERED BY SUBCLASSES C10G, C10K; LIQUEFIED PETROLEUM GAS; ADDING MATERIALS TO FUELS OR FIRES TO REDUCE SMOKE OR UNDESIRABLE DEPOSITS OR TO FACILITATE SOOT REMOVAL; FIRELIGHTERS
- C10L5/00—Solid fuels
- C10L5/02—Solid fuels such as briquettes consisting mainly of carbonaceous materials of mineral or non-mineral origin
- C10L5/06—Methods of shaping, e.g. pelletizing or briquetting
Abstract
ABSTRACT OF THE DISCLOSURE
Agglomeration type beneficiation processes for separating particulate solids from mixtures in which they are incorporated. The agglomerant is a fluorocarbon.
Agglomeration type beneficiation processes for separating particulate solids from mixtures in which they are incorporated. The agglomerant is a fluorocarbon.
Description
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AGGLO~ERATION TYPE COAI. RECOVERY PROCESSES
The present invention relates to processes for recover-ing coal in a commercially valuable form. It relates, more specifically, to novel, improved processes of that character in which an agglomeration promoting additive lor agglomerant) is employed in conjunction with mechanical action to effect the separation of coal particles from mineral m~tter associated there-with in a slurry and the subsequent coalescence of those particles into flocs or agglomerates which can b~ recovered from the slurry.
Certain terms used herein are defined as follows:
Raw coal -- a composite of coal and mineral matter which constitutes the feedstock ~or a process designed to remove mineral matter therefrom. The raw coal which the process disclosed and claimed herein is designed to beneficiate is the black water from a hydrobeneficiation plant, the culm from a sludge pond, or other material of ~mall particle size~
Product coal -- the carbonaceous coal phase generated in and recovered from a specified cleaning process.
Processes of the character first described above, using
AGGLO~ERATION TYPE COAI. RECOVERY PROCESSES
The present invention relates to processes for recover-ing coal in a commercially valuable form. It relates, more specifically, to novel, improved processes of that character in which an agglomeration promoting additive lor agglomerant) is employed in conjunction with mechanical action to effect the separation of coal particles from mineral m~tter associated there-with in a slurry and the subsequent coalescence of those particles into flocs or agglomerates which can b~ recovered from the slurry.
Certain terms used herein are defined as follows:
Raw coal -- a composite of coal and mineral matter which constitutes the feedstock ~or a process designed to remove mineral matter therefrom. The raw coal which the process disclosed and claimed herein is designed to beneficiate is the black water from a hydrobeneficiation plant, the culm from a sludge pond, or other material of ~mall particle size~
Product coal -- the carbonaceous coal phase generated in and recovered from a specified cleaning process.
Processes of the character first described above, using
2() liquid hydrocarbons as agglomeration promo ing additives, h~ve been available for at least sixty years. Such processes are disclosed in Brisse et al, Convertol Proces~, MINli~G ENGINEERING, February 1958, pp. 258-261; AGGLO~ERATION 77, Vol. 2~ K.V.S. Sastry, Ed., American Institute o Mining, Metallurglcal & Petroleum Engineers, Inc., New York, New York, 1977, chapters 54-56, pp. 910-951; and in U.S. Patents Nos. 2,744,626 i5sued May 8, 1956, to R~erink et al; 2,769,537 issued November 6~ 1956, to .. ..
~`, ., 1.
Reerink et al; 2,769,538 issued November 6, 1956, to Reerink et al; 2,781,904 issued February 19, 1957, to Reerink e-t al;
2,842,319 issued July 8, 1958, to Reerink et al; 3,045,818 issued July 24, 1962, to Muschenborn et al; 3,268,071 issued August 23, 1966,to Puddington et al; 3,637,464 issued January 25, 1972, to Walsh; and 4,033,729 issued July 5, 1977, to Capes et al.
One disadvantage of this prior art process is that the recovery of even a part of the agglomeration promoting additive requires that the product coal agglomerates be heated at a tempera-ture of 250-350C (482-662F). This is economically unattractive.
Furthermore, temperatures of the magnitude in question can cause unwanted changes in the composition of the product coal.
Because of the cost of, and problems involved in, xecover-ing agglomeration promoting additives of the conventional type, they have heretofore apparently, for the most part, simply been left on the product coal and lost to the process. At the current elevated prices of the hydrocarbons employed as agglomerating agents, this can make the above-described coal cleaning process economically unattractive.
I have now discovered that the disadvantages of the here-tofore proposed, agglomeration type coal cleaning process discussed above can be overcome by employing as agglomeration promoting addi-tives certain fluorinated derivatives of methane and ethane; i.e~, compositions of the class generally designated by the generic texm "fluorocarbonsO" Useful fluorocarbons include:
l-Chloro-2,2,2-trifluoroethane 1,1-Dichloro-2,2,2-trifluoroethane Dichlorofluoromethane 1,1,2,2-Tetrachloro-1,2-difluoroethane : ~9~37~4 i I l-Chloro-2-fluoroethane i 1,1,2-Trichloro-1~2,2-trifluoroethane Dichloro-1,2,2,2-tetrafluoroethane Trichlorofluoromethane Mixtures of the foregoing compounds can also be employed.
O~ the listed compounds, ~11 but the last three are at the present time prohably too expensive to be practical from an economic viewpoint. And, of the latter, 1,1,2-trichloro- 1 !i ;
1, ,2 trifluoroethane and trichlorofluoromethane are preferred because of their optimum physical properties, lack of chemical ;acti~ity, and relatively low cost.
The boiling points of the fluorocarbons I employ are relatively low. Because of this and their low latent heats of va~orization, they can be separated from the product coal agglomerates at a modest co~t. P~ecovery rates approaching 100 percent are easily attainedO
Also, the fluorocarbons I employ do not form azeotropes with moisture associated with the product coal to ;;any commexcially significant extent. This is important because azeotropes can be xesolved into their components ! only at relatively high cost.
Yet another advantage of my novel process is that it can be carried out at ambien~ temperature and pressure or at temperatures and pressures approaching ambient.
Still another important advantage of my invention, suggested above, is that the ~luorocarbons I employ do not react chemically with coal under the process conditions I use. This i5 important because contaminated coals are undesirable. In the case of steaming coals chemical contaminants can cause boiler corrosion.
Co~taminated coking coals can alter the chemistry of the , -3-: ' ~,,, ,~, I
~31~7~
reactions in which they are employed in unwanted directiorls.
Chemical contamination may also make it necessary to purify the fluorocarbon before it is recycled to the process.
This, potentially, makes the entire process economically unattrac-tiv~.
Furthermore, because the fluorocarbons I employ are chemically inert under p~ocess conditions, my novel process can be carried out without generating the pollutants attributable Ito many coal cleaning processes.
, ~ther coal beneficiation processes which employ fluoro-~car~ons are described in U.S. patent No. 4,173,530 issued November .; 6, 1979, to Smith et al and in a series o~ divisional cascs based on the same disclosure as that patent.
' Speci~ically, Smith e~ al disclose a process of the :' gravity separation or sink-float type in which a fluorocarbcn is used as the parting or gravi$y separation liquid. Gravity ; separation employs Archimedes' principle to resolve raw coàl into product coal and ~ineral solids. Agglomeration-type processes, the type disclosed herein~ on the other hand involve quite different physical phenomena as is evident from, for example, . the introductory portions of the Puddington et al patent identified Il above.
From the foregoing, it will be apparent to the reader that the primary object of the present invention resides in the provis.ion of novel~ improved methods for separating coal I~ .
from mineral matter associated therewith.
, Another important but more specific object of the :invention resides in the provision of a process of ~he character just described in which an additive is introduced into an ,.aqueous sluxry of the raw coal to promote the separation of ..;, 11 .. _ . . . .. . _ . .. . .. . .
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the coal particles from the mineral matter associated therewi~h and the coalescence oE said coal into agglomerates and in which provision i.s made for subseqently recovering the agglomer-ation promoting additive from the product coal agglomerates.
Other important but still more specific objects of my invention reside in the provision of processes in accord with the preceding object in which:
the agglomeration promoting additive can be reco~ered from the product coal agglomerates with only a modest, commercially viable expenditure of energy;
the agglomeration promoting additive can be recovered from the product coal agglomerates without generating ecologically undesirable wastes;
~ he agglomeration ~}o,.loting additive can.be recovered from the product coal agglomerates under condition~ which are, or approach, ambient, thereby eliminating the safety and other problems appurtenant to the use of high temperatures and pressures.
The oh~ects are broadly attained hy the invention which contemplates a process or recovering particles of coal from a particulate composite having a top size of ca 0.6 mm in which the particles of coal are mixed with particles of mineral matter to effect a physical separation of the existent coal particles from the existent particles of mineral matter essen-tially without further liberation of mineral matter from the coal. The process comprises the steps of: agitating the composite, wlthout any significant reduction in size o~ the particles making up the composite 9 in an aqueous carrier contain-ing a fluorocarbon agglomeration promoting additive with 0 respect to whlch the coal is hydrophobic, to effect a coalescence of the coal particles into product coal agglomerates and the -4a-'7~
e~ection of mineral matter particles into dispersion in the aqueous carrier, and recovering the product coal agglomerates from the aqueous carrier. The agglomera-tion promoting addi~ es that can be used in the inventive process are the eight listed as useful above in this disclosure at page 2, line 28 to page 3, line 5.
Other important objects, advantages, and features of the present invention will be apparent from the foregoing and the appended claims and as the ensuing detailed description and discussion proceeds in conjunction with the appended drawings in which:
Figure 1 is a flow diagram of one process for beneficiating coal in accord with the principles of the present invention; and Figure 2 is a graph showing the effect of the important process variables on the ash content of the product coal.
Referring now to Figure 1, the separation of coal from the mineral matter associated therewith, the su~sequent agglomeration of the coal particles, and the ejection of mineral matter and water from the agglomerates is carried out in an agglomerator 10 which may be, for example, a homogenizer as described in U.S. Patent No. 2,744,626 issued May 8, 1956, to Reerink et al or a tumbler as described in U.S. Patent No. 3,471,267 issued October 7, 1965, to Capes et al. Or, as shown in the drawing, the agglomerator may simply be a casing 1~ housing propellor-type agitators 14 rotated by a drive 16 of conventional construction~ This arrangement moves the raw coal along casing 12 as the separation and agglomeration of the product coal and the ejection of water and mineral matter from the agglomerates take place.
Agglomerator 10 provides mechanical forces which jam the coal particles in the raw coal into agglomerates of ~9~3'7~39~
the wanted character and which eject the mineral matter ana water from the agglomerates. In addition, it generates forces which knead or work the agglomerates to expel additional mineral matter and water therefrom.
; The separation may be carried out at ambient temperature and pressure.
Raw coal and the selected agglomeration promoting additive are introduced into agglomerator 10 through transfer devices indicated generally by reference characters 18 and 20.
Such water as may be necessary to form a slurry with appropriate characteristics is introduced through a separate conduit (not shown) or premixed with the coal, depending upon the character of the agglomerator.
For my process to operate efficiently, the size consist of the coal should not exceed 0.6 mm; i.e., it is e~ficient fox coals with size consists up to 0.6 mm x 0. On the other hand ; coals with si~e consists of 0.02 mm x 0 (and even smaller) can be readily cleaned with my process.
- The minimum amount of additive I employ is that necessary for an efficient agglomeration o~ the particles of product coal to be effected. Three to ten percent by weight of the additive based on the weight of the liquid carrier-raw coal-additive system serves that purpose.
Typically, nothing will be gained by employing more than 500 pounds of agglomerant per ton of coal; but the efficiency of the process will begin to deteriorate, and the amount of ash in the product coal will begin to increase, as ; the amount of agglomerant is decreased below that level.
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~ minimum of 70 percent water based on the weight of the raw coal-additive-liquid system is maintained in agglomerator 10. Lower amounts do not provide a sufficiently large body of liquid to keep the mineral matter suspended in ~the aqueous carrier.
The maximum amount of water and agglomeration promoting additive that can be tolerated in agglomerator 10 depends upon , I
the type of e~uipment that is employed and can range up to ' 98 percent of water and additive combined based upon the weight 10 of the raw coal.
Typically, the solids content of the raw coal-agglomerant-water system will be in the range of five to ten weight percent.
" The time for which agglomeration is carriedout is also important in the successful practice of my invention.
Typically, an agglomeration (or throughput) time of abou~ one minute will be employed. Reductions to shorter perlods result in higher product coal ash contents while ~ longer periods produce increased energy consumption and component wear without producing any significant additional reduction in product coal ash content.
, ' ' !' i 1~98'7~'~
` A strictly optional step in the process as so far described is to subject the coal particles to particle size reduction prior to agglomeration. This technique can be employed to reduce the sulfur content of the product coal and/or its mineral content. The particle size reduction can be carried out in a ball mill such as is shown at 21, for example.
The foregoing technique is readily distinguishable from the process disclosed and claimed in U.S. patent No. 4,186,887 which is assigned to the same assignee as thepresent case. In 10 the previously patented process, milling (or size reduction) is employed in the agglomeration process to reduce the mineral content of the coal being cleaned to an absolute minimum.
Figure 2 illustrates, graphically, the effect that actual tests showed the major process variables to have on the ash content of the product coal. Each of these variables was investigated with the other variables optimized. Generally, as the percentage of solids in the water-agglomerant-raw coal system increased, the ash in the product coal increased. ~gglomerat-ing times shorter than one minute resulted in increased ash.
2~ Agglomerant concentrations of less than 0.3 gms/gm of coal also produced an increase in ash.
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As discussed in copending Canadian application No.
339,011, filed November 2, 1979, now Canadian patent No.
1,130,231, it is deslrable, in many cases, to add calcium oxide in either hydrated or anhydrous form to the slurry during the agglomera-tion process to promote the separation of pyritic sulfur from the product coal.
Pyritic sulfur content~ of only a fraction of one percent have consistently been obtained by employing that technique.
Also, in the course of agglomeration, the calcium oxide is associated with the product coal in a manner which increases the hydrogasification and steam gasification reactivities of the coal, another benefit of decided economic importance~
Furthermore, when coal fortified with calcium oxide in the manner just described is burned, the calcium ions react with sulfur remaining in the coal, ~ormin~ a p1-ecipitate that can be readily removed from the combustion products. Thus, the presence of calcium ions in the coal produced by my novel process actually facilitates the removal of pollutants from the combustion products.
.~
The calcium oxide, i employed, is introduced into agglomerator 10 through transfer device 2~. From 0.15 to 0.53 percent of calcium oxide (calculated as CaO) based on the weight of the water in the agqlomerator is employed. It is preferred that the calcium oxide be dosed or metered ko the ag~lomerator over the period of coal particle separation and agglomeration as this much more effectively promotes the rejection of pyritic sulfur from the pxoduct coal agglomerates than a one-time addition does.
The product coal agglomerates, the aqueous carrier, and the mineral matter are discharaed from agglomerator 10 through a conventional sieve bend or Vor-sieve 24 here the mineral matter and water are separated from the product coal agqlomerates.
The ~ater and mineral matter are optionally directed to a conventional scrubber 26 to recover agglomeration promoting additive carried from ag~lomexator 10 therewith (typically about 200 ppm) and then to a thickener 28. Suitable thickeners are described in Taggart, HA~DBOOK OF MINERAL DRESS IMG, John Wiley o & So~s, Inc., New York, New York, 1927, pp. 15-04 -- 15-26.
The mineral matter consolidated in the thickener may be transferred to a refuse heap or landfill, for example;
and the water can be recycled.
The product coal agglomerates with their accompanying burdens of agglomeration promoting additive and moisture are transferred to an evaporator 30 where at least the additive is stripped from the agglcmexates. Moisture associated there~
with may also be stripped from the coal in evaporator 30.
However, it is not in every case necessary that all, or even 30 any, of this moisture be removed; and it i5 an important feature ~~ ,tJ
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o~ my invention that an essentially quantitative (9g% plus) recovery of additive can be made without removing the water.
I Suitable evaporators are described in patent No.
4,173,530.
Dried agglomerates discharged from evaporator 30 are ready for utilization.
The aqueous phase istreate~ as described above.
It is a feature of the present invention that evaporation ;of the fluorocarbon additive as just described can be effected at a fast enough rate to substantially reduce the vapor pressure over, and, as a consequence, the cost of recovering the moisture - from the coal. This has been demonstrated by evaporating 15% by weight of trichlorofluoromethane from a bed of fine coal containing 6% by weight moisture at a temperature only 6C
above the 24C (75F) boiling point o~ that compound. In less than 10 minutes the moisture content o~ the coal had been reduced by ca. 2%. At the same temperature it would have taken several hours for the coal to have lost that much moisture absent the codistillation effected by the fluorocarbon.
1 Other of the agglomerants I employ, notably 1,1,2-trichloro-1,2,2-trifluoroethane, exhibit this novel codistillation ,1 "' capability to an even greater, and therefore more beneficial, extent.
! Mechanical removal of liquid can be employed in association with evaporator 30 to reduce the load on and the cost of operating the latter. Product coal from sieve bend 2~
will typically have a 40 weight percent water content. Simply by .. ..
` passing typical agglomerants through the nip between two conven-tional wringer rolls, as shown diagrammatically in the drawing at 32, the moisture content of the agglomerates can be reduced to on the order of 8 percent by weight.
.. .... .. . . . . ...
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The fluorocarbon agglomeration promoting additive and any moisture recovered from the evaporator -therewith are transferred to a fluorocarbon recovery unit 34 of the type described in patent ~o. 4,173,530, for example, as is the ~luorocarbon vapor recovered in scrubber 26. The water and additive are co-condensed and can then be readily separated due to their vir~ually complete immiscibility.
The fluorocarbon additive is then purged o non-condensible gases and recycled by way of an agglomerant storage tank 35, and the water may also be recycl~d.
The examples which rollow describe representative tests which illustrate various facets of my novel coal cleaning process.
In each run ca. 100 g of the coal in aqueous slurry was agitated with the agglomeration promoting additive in a conventional ~itchen blender for two minutes~
` !
The agglomerates were separated from the aqueous mineral matter phase of the slurry with a 6 in. by 2 in. curved sieve bend and then expressed between two steel rolls, reducing the moisture content of the agglomerates rom ca. 40 to less than 10 weight percent.
The "dryl' agglomerates were then recovered and subjected to proximate analysis.
All data are on a dry bàsis, and all percentages except for ~TU yield are based on weight.
EXA~IPLE I
Sludge from the thickener of an existlng hydro-beneficiation plant containing ca. 10 weight percent solids was subjected to agglomeration type benefi~iation using the process and equipment described above and 1,1,2-trichloro-:1~98'~
1,2,2-trifluoroethane as the ag~lomerant.
The results are tabulated below:
Table l ., !
Coal: Predominantly Upper Freeport Weight Yield % - 81.30 BTU Yield ~ - 94.50 ,;
* M/BTU = 106 BTU
** MAF = moisture and ash free . . .
Slurries (40 weight percent solids) of Upper Freeport coal drawn from the same thlckener circult were similarly beneficiated. "Best run" results follow:
.1 .. . . ..... . .. . . . ..
Table 2 ~, Sa~,E,leSample lA7t.% Total Lbs. Sulfur/ Wt.~ BrU
Number Description Wt.~ Ash Sulfur B~7~1b. 106 BTU Wt.% Yield Yield Raw Slurry 22.65 1.09+0.04 11,9570.91 Coal-5Slurry 6.27 0.76+0.03 14,6400.52 77.1 87.7 Raw Coal-7Slurry 22.03 1.15~0.03 11,9720.96 - -Coal-7Slurry 8.14 1.31~0.03 14,3470.91 89.3 99.5 Coal-8Slurry 24.92 1.52+0.04 11,4641.33 _ _ ProdllctSlurry 4.92 1.02+0.05 14,862* 0.69 62.0 80.4 * Calcu~ated BTU/lb value from the ash-BTU/lb relationship: BTU/lb = -167.6 (Wt.~ Ash) ~ 15,687 1: L98~7~
EX~PLE III
That my novel process is capable of producing agglomer-ates with a high degree of structural integxity as well as efficiently separating the coal from the mineral matter associated therewith was demonstrated by size consist before and after beneficiation analyses of a sludge, again taken from the sarne thickener circuit. The results follow:
Table 3 Raw Coal Product Coal 10 Size Fraction(Wet Screened)(Dry Screened) +9m* - 17.2 9m x 16m - 43.6 16m x 28m 1.5 23.1 28m x 60m 5.5 11.7 60m x 100m 6.6 1.5 100m x 200m 14.1 0.7 200m x 325m 9.4 0.7 325m x 400m 6.0 0.4 400m x 0 57.0, 1.1 20 TOTAL 100.1 100.0 * m = Tyler mesh The larger size consist of the product coal is due to solid particle adhesion. That these agglomerates have consider-able strength is evident as the very act of sieve sizing places severe mechanical stresses on the particles as they are vibrated i~
across the sieve surface and through the respective sieves.
. :
;
;!
, . , . ., . .. , .. ~ ~ , . . .... ... . . . .. .. . . .
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EXAMPLE IV
Seven agglomeration type beneficiations as described in EX~IPLF I were made of an Upper Freeport "grab" sam~le having the following size consist~
Table 4 Particle Weight Si~e Percent ~60m* 0. 3 60;n x lOOm 8 . 9 10 '' lOOm x 200m21. 0 ' 200m x 32Sm12. 4 325m x 400mS. 0 400m x 0 52 ~ 4 , ;~ * m = Tyler mesh : . , The results are tabulated below:
Table 5 Raw Product Coal Coal B C D E F G H
20 Ash 18.17 7.45 4.01~ 6.033.93 5.654.08 5.36 Total Sulfur% 1.24 1.06 0.771.03 0.771.06 - 1.06 Weight Yield96 - 85.60 61.50* 86.60 74.60* 84.40 72020 83.90 * Average~ Yield~;
.~9~'7~3~
E~AMPLE V
That rny novel process can be used ~ith equal effective-ness to clean other coals has been demonstrated hy a large number cf tests conducted on 60m x 0 coals in the same manner as the test reported in EX~MPIE I. The results of representative ones of those tests are tabulated below:
I`able 6 RAW CO~. PRODUCT COAL
Coal Se~m County, S-tate ~sh BTU/~ Ash PTU/lb Pittsburgh* Washington, PA 31.23 9,448 5.54 13,944 er hittal~ing* Washinyton, PA 24.87 11,024 5.74 14,332 Ridge~lountain** Ca~pbell, TN 8.52 13,326 3.59 14,125 Hazal^d** PeL~, .~ 7.48 13,513 3.53 14,103 Illillois No. 6** Fran].lin, IL 7.68 13,388 3.13 14,087 I'e rles5 Iayette, ~14.8812,983 2.60 14,700 Oh-io No. 9 ~lorg~n, OII 23.25 10,700 7.70 13~20 * Slurry Pond SouLce ** Washed Coal Source '~3 r~
The invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The presen-t embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing descri~tion; and all changes which come within the meaning and range of equivalency of -the claims are therefore intended to be embraced therein.
"
. ~
-~8-
~`, ., 1.
Reerink et al; 2,769,538 issued November 6, 1956, to Reerink et al; 2,781,904 issued February 19, 1957, to Reerink e-t al;
2,842,319 issued July 8, 1958, to Reerink et al; 3,045,818 issued July 24, 1962, to Muschenborn et al; 3,268,071 issued August 23, 1966,to Puddington et al; 3,637,464 issued January 25, 1972, to Walsh; and 4,033,729 issued July 5, 1977, to Capes et al.
One disadvantage of this prior art process is that the recovery of even a part of the agglomeration promoting additive requires that the product coal agglomerates be heated at a tempera-ture of 250-350C (482-662F). This is economically unattractive.
Furthermore, temperatures of the magnitude in question can cause unwanted changes in the composition of the product coal.
Because of the cost of, and problems involved in, xecover-ing agglomeration promoting additives of the conventional type, they have heretofore apparently, for the most part, simply been left on the product coal and lost to the process. At the current elevated prices of the hydrocarbons employed as agglomerating agents, this can make the above-described coal cleaning process economically unattractive.
I have now discovered that the disadvantages of the here-tofore proposed, agglomeration type coal cleaning process discussed above can be overcome by employing as agglomeration promoting addi-tives certain fluorinated derivatives of methane and ethane; i.e~, compositions of the class generally designated by the generic texm "fluorocarbonsO" Useful fluorocarbons include:
l-Chloro-2,2,2-trifluoroethane 1,1-Dichloro-2,2,2-trifluoroethane Dichlorofluoromethane 1,1,2,2-Tetrachloro-1,2-difluoroethane : ~9~37~4 i I l-Chloro-2-fluoroethane i 1,1,2-Trichloro-1~2,2-trifluoroethane Dichloro-1,2,2,2-tetrafluoroethane Trichlorofluoromethane Mixtures of the foregoing compounds can also be employed.
O~ the listed compounds, ~11 but the last three are at the present time prohably too expensive to be practical from an economic viewpoint. And, of the latter, 1,1,2-trichloro- 1 !i ;
1, ,2 trifluoroethane and trichlorofluoromethane are preferred because of their optimum physical properties, lack of chemical ;acti~ity, and relatively low cost.
The boiling points of the fluorocarbons I employ are relatively low. Because of this and their low latent heats of va~orization, they can be separated from the product coal agglomerates at a modest co~t. P~ecovery rates approaching 100 percent are easily attainedO
Also, the fluorocarbons I employ do not form azeotropes with moisture associated with the product coal to ;;any commexcially significant extent. This is important because azeotropes can be xesolved into their components ! only at relatively high cost.
Yet another advantage of my novel process is that it can be carried out at ambien~ temperature and pressure or at temperatures and pressures approaching ambient.
Still another important advantage of my invention, suggested above, is that the ~luorocarbons I employ do not react chemically with coal under the process conditions I use. This i5 important because contaminated coals are undesirable. In the case of steaming coals chemical contaminants can cause boiler corrosion.
Co~taminated coking coals can alter the chemistry of the , -3-: ' ~,,, ,~, I
~31~7~
reactions in which they are employed in unwanted directiorls.
Chemical contamination may also make it necessary to purify the fluorocarbon before it is recycled to the process.
This, potentially, makes the entire process economically unattrac-tiv~.
Furthermore, because the fluorocarbons I employ are chemically inert under p~ocess conditions, my novel process can be carried out without generating the pollutants attributable Ito many coal cleaning processes.
, ~ther coal beneficiation processes which employ fluoro-~car~ons are described in U.S. patent No. 4,173,530 issued November .; 6, 1979, to Smith et al and in a series o~ divisional cascs based on the same disclosure as that patent.
' Speci~ically, Smith e~ al disclose a process of the :' gravity separation or sink-float type in which a fluorocarbcn is used as the parting or gravi$y separation liquid. Gravity ; separation employs Archimedes' principle to resolve raw coàl into product coal and ~ineral solids. Agglomeration-type processes, the type disclosed herein~ on the other hand involve quite different physical phenomena as is evident from, for example, . the introductory portions of the Puddington et al patent identified Il above.
From the foregoing, it will be apparent to the reader that the primary object of the present invention resides in the provis.ion of novel~ improved methods for separating coal I~ .
from mineral matter associated therewith.
, Another important but more specific object of the :invention resides in the provision of a process of ~he character just described in which an additive is introduced into an ,.aqueous sluxry of the raw coal to promote the separation of ..;, 11 .. _ . . . .. . _ . .. . .. . .
7~
the coal particles from the mineral matter associated therewi~h and the coalescence oE said coal into agglomerates and in which provision i.s made for subseqently recovering the agglomer-ation promoting additive from the product coal agglomerates.
Other important but still more specific objects of my invention reside in the provision of processes in accord with the preceding object in which:
the agglomeration promoting additive can be reco~ered from the product coal agglomerates with only a modest, commercially viable expenditure of energy;
the agglomeration promoting additive can be recovered from the product coal agglomerates without generating ecologically undesirable wastes;
~ he agglomeration ~}o,.loting additive can.be recovered from the product coal agglomerates under condition~ which are, or approach, ambient, thereby eliminating the safety and other problems appurtenant to the use of high temperatures and pressures.
The oh~ects are broadly attained hy the invention which contemplates a process or recovering particles of coal from a particulate composite having a top size of ca 0.6 mm in which the particles of coal are mixed with particles of mineral matter to effect a physical separation of the existent coal particles from the existent particles of mineral matter essen-tially without further liberation of mineral matter from the coal. The process comprises the steps of: agitating the composite, wlthout any significant reduction in size o~ the particles making up the composite 9 in an aqueous carrier contain-ing a fluorocarbon agglomeration promoting additive with 0 respect to whlch the coal is hydrophobic, to effect a coalescence of the coal particles into product coal agglomerates and the -4a-'7~
e~ection of mineral matter particles into dispersion in the aqueous carrier, and recovering the product coal agglomerates from the aqueous carrier. The agglomera-tion promoting addi~ es that can be used in the inventive process are the eight listed as useful above in this disclosure at page 2, line 28 to page 3, line 5.
Other important objects, advantages, and features of the present invention will be apparent from the foregoing and the appended claims and as the ensuing detailed description and discussion proceeds in conjunction with the appended drawings in which:
Figure 1 is a flow diagram of one process for beneficiating coal in accord with the principles of the present invention; and Figure 2 is a graph showing the effect of the important process variables on the ash content of the product coal.
Referring now to Figure 1, the separation of coal from the mineral matter associated therewith, the su~sequent agglomeration of the coal particles, and the ejection of mineral matter and water from the agglomerates is carried out in an agglomerator 10 which may be, for example, a homogenizer as described in U.S. Patent No. 2,744,626 issued May 8, 1956, to Reerink et al or a tumbler as described in U.S. Patent No. 3,471,267 issued October 7, 1965, to Capes et al. Or, as shown in the drawing, the agglomerator may simply be a casing 1~ housing propellor-type agitators 14 rotated by a drive 16 of conventional construction~ This arrangement moves the raw coal along casing 12 as the separation and agglomeration of the product coal and the ejection of water and mineral matter from the agglomerates take place.
Agglomerator 10 provides mechanical forces which jam the coal particles in the raw coal into agglomerates of ~9~3'7~39~
the wanted character and which eject the mineral matter ana water from the agglomerates. In addition, it generates forces which knead or work the agglomerates to expel additional mineral matter and water therefrom.
; The separation may be carried out at ambient temperature and pressure.
Raw coal and the selected agglomeration promoting additive are introduced into agglomerator 10 through transfer devices indicated generally by reference characters 18 and 20.
Such water as may be necessary to form a slurry with appropriate characteristics is introduced through a separate conduit (not shown) or premixed with the coal, depending upon the character of the agglomerator.
For my process to operate efficiently, the size consist of the coal should not exceed 0.6 mm; i.e., it is e~ficient fox coals with size consists up to 0.6 mm x 0. On the other hand ; coals with si~e consists of 0.02 mm x 0 (and even smaller) can be readily cleaned with my process.
- The minimum amount of additive I employ is that necessary for an efficient agglomeration o~ the particles of product coal to be effected. Three to ten percent by weight of the additive based on the weight of the liquid carrier-raw coal-additive system serves that purpose.
Typically, nothing will be gained by employing more than 500 pounds of agglomerant per ton of coal; but the efficiency of the process will begin to deteriorate, and the amount of ash in the product coal will begin to increase, as ; the amount of agglomerant is decreased below that level.
7~'~
~ minimum of 70 percent water based on the weight of the raw coal-additive-liquid system is maintained in agglomerator 10. Lower amounts do not provide a sufficiently large body of liquid to keep the mineral matter suspended in ~the aqueous carrier.
The maximum amount of water and agglomeration promoting additive that can be tolerated in agglomerator 10 depends upon , I
the type of e~uipment that is employed and can range up to ' 98 percent of water and additive combined based upon the weight 10 of the raw coal.
Typically, the solids content of the raw coal-agglomerant-water system will be in the range of five to ten weight percent.
" The time for which agglomeration is carriedout is also important in the successful practice of my invention.
Typically, an agglomeration (or throughput) time of abou~ one minute will be employed. Reductions to shorter perlods result in higher product coal ash contents while ~ longer periods produce increased energy consumption and component wear without producing any significant additional reduction in product coal ash content.
, ' ' !' i 1~98'7~'~
` A strictly optional step in the process as so far described is to subject the coal particles to particle size reduction prior to agglomeration. This technique can be employed to reduce the sulfur content of the product coal and/or its mineral content. The particle size reduction can be carried out in a ball mill such as is shown at 21, for example.
The foregoing technique is readily distinguishable from the process disclosed and claimed in U.S. patent No. 4,186,887 which is assigned to the same assignee as thepresent case. In 10 the previously patented process, milling (or size reduction) is employed in the agglomeration process to reduce the mineral content of the coal being cleaned to an absolute minimum.
Figure 2 illustrates, graphically, the effect that actual tests showed the major process variables to have on the ash content of the product coal. Each of these variables was investigated with the other variables optimized. Generally, as the percentage of solids in the water-agglomerant-raw coal system increased, the ash in the product coal increased. ~gglomerat-ing times shorter than one minute resulted in increased ash.
2~ Agglomerant concentrations of less than 0.3 gms/gm of coal also produced an increase in ash.
i , '7~
As discussed in copending Canadian application No.
339,011, filed November 2, 1979, now Canadian patent No.
1,130,231, it is deslrable, in many cases, to add calcium oxide in either hydrated or anhydrous form to the slurry during the agglomera-tion process to promote the separation of pyritic sulfur from the product coal.
Pyritic sulfur content~ of only a fraction of one percent have consistently been obtained by employing that technique.
Also, in the course of agglomeration, the calcium oxide is associated with the product coal in a manner which increases the hydrogasification and steam gasification reactivities of the coal, another benefit of decided economic importance~
Furthermore, when coal fortified with calcium oxide in the manner just described is burned, the calcium ions react with sulfur remaining in the coal, ~ormin~ a p1-ecipitate that can be readily removed from the combustion products. Thus, the presence of calcium ions in the coal produced by my novel process actually facilitates the removal of pollutants from the combustion products.
.~
The calcium oxide, i employed, is introduced into agglomerator 10 through transfer device 2~. From 0.15 to 0.53 percent of calcium oxide (calculated as CaO) based on the weight of the water in the agqlomerator is employed. It is preferred that the calcium oxide be dosed or metered ko the ag~lomerator over the period of coal particle separation and agglomeration as this much more effectively promotes the rejection of pyritic sulfur from the pxoduct coal agglomerates than a one-time addition does.
The product coal agglomerates, the aqueous carrier, and the mineral matter are discharaed from agglomerator 10 through a conventional sieve bend or Vor-sieve 24 here the mineral matter and water are separated from the product coal agqlomerates.
The ~ater and mineral matter are optionally directed to a conventional scrubber 26 to recover agglomeration promoting additive carried from ag~lomexator 10 therewith (typically about 200 ppm) and then to a thickener 28. Suitable thickeners are described in Taggart, HA~DBOOK OF MINERAL DRESS IMG, John Wiley o & So~s, Inc., New York, New York, 1927, pp. 15-04 -- 15-26.
The mineral matter consolidated in the thickener may be transferred to a refuse heap or landfill, for example;
and the water can be recycled.
The product coal agglomerates with their accompanying burdens of agglomeration promoting additive and moisture are transferred to an evaporator 30 where at least the additive is stripped from the agglcmexates. Moisture associated there~
with may also be stripped from the coal in evaporator 30.
However, it is not in every case necessary that all, or even 30 any, of this moisture be removed; and it i5 an important feature ~~ ,tJ
7~
o~ my invention that an essentially quantitative (9g% plus) recovery of additive can be made without removing the water.
I Suitable evaporators are described in patent No.
4,173,530.
Dried agglomerates discharged from evaporator 30 are ready for utilization.
The aqueous phase istreate~ as described above.
It is a feature of the present invention that evaporation ;of the fluorocarbon additive as just described can be effected at a fast enough rate to substantially reduce the vapor pressure over, and, as a consequence, the cost of recovering the moisture - from the coal. This has been demonstrated by evaporating 15% by weight of trichlorofluoromethane from a bed of fine coal containing 6% by weight moisture at a temperature only 6C
above the 24C (75F) boiling point o~ that compound. In less than 10 minutes the moisture content o~ the coal had been reduced by ca. 2%. At the same temperature it would have taken several hours for the coal to have lost that much moisture absent the codistillation effected by the fluorocarbon.
1 Other of the agglomerants I employ, notably 1,1,2-trichloro-1,2,2-trifluoroethane, exhibit this novel codistillation ,1 "' capability to an even greater, and therefore more beneficial, extent.
! Mechanical removal of liquid can be employed in association with evaporator 30 to reduce the load on and the cost of operating the latter. Product coal from sieve bend 2~
will typically have a 40 weight percent water content. Simply by .. ..
` passing typical agglomerants through the nip between two conven-tional wringer rolls, as shown diagrammatically in the drawing at 32, the moisture content of the agglomerates can be reduced to on the order of 8 percent by weight.
.. .... .. . . . . ...
7~
The fluorocarbon agglomeration promoting additive and any moisture recovered from the evaporator -therewith are transferred to a fluorocarbon recovery unit 34 of the type described in patent ~o. 4,173,530, for example, as is the ~luorocarbon vapor recovered in scrubber 26. The water and additive are co-condensed and can then be readily separated due to their vir~ually complete immiscibility.
The fluorocarbon additive is then purged o non-condensible gases and recycled by way of an agglomerant storage tank 35, and the water may also be recycl~d.
The examples which rollow describe representative tests which illustrate various facets of my novel coal cleaning process.
In each run ca. 100 g of the coal in aqueous slurry was agitated with the agglomeration promoting additive in a conventional ~itchen blender for two minutes~
` !
The agglomerates were separated from the aqueous mineral matter phase of the slurry with a 6 in. by 2 in. curved sieve bend and then expressed between two steel rolls, reducing the moisture content of the agglomerates rom ca. 40 to less than 10 weight percent.
The "dryl' agglomerates were then recovered and subjected to proximate analysis.
All data are on a dry bàsis, and all percentages except for ~TU yield are based on weight.
EXA~IPLE I
Sludge from the thickener of an existlng hydro-beneficiation plant containing ca. 10 weight percent solids was subjected to agglomeration type benefi~iation using the process and equipment described above and 1,1,2-trichloro-:1~98'~
1,2,2-trifluoroethane as the ag~lomerant.
The results are tabulated below:
Table l ., !
Coal: Predominantly Upper Freeport Weight Yield % - 81.30 BTU Yield ~ - 94.50 ,;
* M/BTU = 106 BTU
** MAF = moisture and ash free . . .
Slurries (40 weight percent solids) of Upper Freeport coal drawn from the same thlckener circult were similarly beneficiated. "Best run" results follow:
.1 .. . . ..... . .. . . . ..
Table 2 ~, Sa~,E,leSample lA7t.% Total Lbs. Sulfur/ Wt.~ BrU
Number Description Wt.~ Ash Sulfur B~7~1b. 106 BTU Wt.% Yield Yield Raw Slurry 22.65 1.09+0.04 11,9570.91 Coal-5Slurry 6.27 0.76+0.03 14,6400.52 77.1 87.7 Raw Coal-7Slurry 22.03 1.15~0.03 11,9720.96 - -Coal-7Slurry 8.14 1.31~0.03 14,3470.91 89.3 99.5 Coal-8Slurry 24.92 1.52+0.04 11,4641.33 _ _ ProdllctSlurry 4.92 1.02+0.05 14,862* 0.69 62.0 80.4 * Calcu~ated BTU/lb value from the ash-BTU/lb relationship: BTU/lb = -167.6 (Wt.~ Ash) ~ 15,687 1: L98~7~
EX~PLE III
That my novel process is capable of producing agglomer-ates with a high degree of structural integxity as well as efficiently separating the coal from the mineral matter associated therewith was demonstrated by size consist before and after beneficiation analyses of a sludge, again taken from the sarne thickener circuit. The results follow:
Table 3 Raw Coal Product Coal 10 Size Fraction(Wet Screened)(Dry Screened) +9m* - 17.2 9m x 16m - 43.6 16m x 28m 1.5 23.1 28m x 60m 5.5 11.7 60m x 100m 6.6 1.5 100m x 200m 14.1 0.7 200m x 325m 9.4 0.7 325m x 400m 6.0 0.4 400m x 0 57.0, 1.1 20 TOTAL 100.1 100.0 * m = Tyler mesh The larger size consist of the product coal is due to solid particle adhesion. That these agglomerates have consider-able strength is evident as the very act of sieve sizing places severe mechanical stresses on the particles as they are vibrated i~
across the sieve surface and through the respective sieves.
. :
;
;!
, . , . ., . .. , .. ~ ~ , . . .... ... . . . .. .. . . .
'7~3~
EXAMPLE IV
Seven agglomeration type beneficiations as described in EX~IPLF I were made of an Upper Freeport "grab" sam~le having the following size consist~
Table 4 Particle Weight Si~e Percent ~60m* 0. 3 60;n x lOOm 8 . 9 10 '' lOOm x 200m21. 0 ' 200m x 32Sm12. 4 325m x 400mS. 0 400m x 0 52 ~ 4 , ;~ * m = Tyler mesh : . , The results are tabulated below:
Table 5 Raw Product Coal Coal B C D E F G H
20 Ash 18.17 7.45 4.01~ 6.033.93 5.654.08 5.36 Total Sulfur% 1.24 1.06 0.771.03 0.771.06 - 1.06 Weight Yield96 - 85.60 61.50* 86.60 74.60* 84.40 72020 83.90 * Average~ Yield~;
.~9~'7~3~
E~AMPLE V
That rny novel process can be used ~ith equal effective-ness to clean other coals has been demonstrated hy a large number cf tests conducted on 60m x 0 coals in the same manner as the test reported in EX~MPIE I. The results of representative ones of those tests are tabulated below:
I`able 6 RAW CO~. PRODUCT COAL
Coal Se~m County, S-tate ~sh BTU/~ Ash PTU/lb Pittsburgh* Washington, PA 31.23 9,448 5.54 13,944 er hittal~ing* Washinyton, PA 24.87 11,024 5.74 14,332 Ridge~lountain** Ca~pbell, TN 8.52 13,326 3.59 14,125 Hazal^d** PeL~, .~ 7.48 13,513 3.53 14,103 Illillois No. 6** Fran].lin, IL 7.68 13,388 3.13 14,087 I'e rles5 Iayette, ~14.8812,983 2.60 14,700 Oh-io No. 9 ~lorg~n, OII 23.25 10,700 7.70 13~20 * Slurry Pond SouLce ** Washed Coal Source '~3 r~
The invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The presen-t embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing descri~tion; and all changes which come within the meaning and range of equivalency of -the claims are therefore intended to be embraced therein.
"
. ~
-~8-
Claims (2)
1. A process for recovering particles of coal from a particulate composite having a top size of ca 0.6 mm in which said particles of coal are mixed with particles of mineral matter to effect a physical separation of the existent coal particles from the existent particles of mineral matter essen-tially without further liberation of mineral matter from the coal, said process comprising the steps of: agitating said composite without any significant reduction in size of the particles making up the composite in an aqueous carrier contain-ing a fluorocarbon agglomeration promoting additive with respect to which the coal is hydrophobic to effect a coalescence of the coal particles into product coal agglomerates and the ejection of mineral matter particles into dispersion in said aqueous carrier and recovering said product coal agglomerates from said aqueous carrier, the fluorocarbon agglomeration pro-moting additive being selected from the group consisting of:
dichlorofluoromethane trichlorofluoromethane 1,1,2,2-tetrachloro-1,2-difluoroethane 1,1,2-trichloro-1,2,2,-trifluoroethane 1,1-dichloro-1,2,2,2-tetrafluoroethane 1-chloro-2,2,2-trifluoroethane 1,1-dichloro-2,2,2-trifluoroethane 1-chloro-2-fluoroethane and mixtures of the foregoing.
dichlorofluoromethane trichlorofluoromethane 1,1,2,2-tetrachloro-1,2-difluoroethane 1,1,2-trichloro-1,2,2,-trifluoroethane 1,1-dichloro-1,2,2,2-tetrafluoroethane 1-chloro-2,2,2-trifluoroethane 1,1-dichloro-2,2,2-trifluoroethane 1-chloro-2-fluoroethane and mixtures of the foregoing.
2. A process as defined in claim 1 in which the composite is comminuted prior to those steps in which the coal is recovered from the composite to ensure that the top size of the particles in said composite has a maximum top size of 0.6 mm as aforesaid and/or to effect a resolution of larger particles in said composite into particles which are primarily coal and particles which are primarily mineral matter and thereby potentiate a reduction in the amount of sulfur and/or other mineral matter associated with the coal in the product coal agglomerates.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US24706581A | 1981-03-24 | 1981-03-24 | |
| US247,065 | 1981-03-24 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1198704A true CA1198704A (en) | 1985-12-31 |
Family
ID=22933411
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000393881A Expired CA1198704A (en) | 1981-03-24 | 1982-01-11 | Agglomeration type coal recovery processes |
Country Status (4)
| Country | Link |
|---|---|
| AU (1) | AU533050B2 (en) |
| CA (1) | CA1198704A (en) |
| DE (1) | DE3206562C2 (en) |
| GB (1) | GB2095284B (en) |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2013188419A1 (en) | 2012-06-11 | 2013-12-19 | Virginia Tech Intellectual Properties, Inc. | Methods for separating and dewatering fine particles |
| US9518241B2 (en) | 2010-02-01 | 2016-12-13 | Virginia Tech Intellectual Properties, Inc. | Method of separating and de-watering fine particles |
| US9789492B2 (en) | 2010-02-01 | 2017-10-17 | Virginia Tech Intellectual Properties, Inc. | Cleaning and dewatering fine coal |
| US11331676B2 (en) | 2010-02-01 | 2022-05-17 | Virginia Tech Intellectual Properties, Inc. | Cleaning and dewatering fine coal |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE3244898C2 (en) * | 1982-12-04 | 1985-04-11 | Chemische Fabrik Stockhausen GmbH, 4150 Krefeld | Process for the separation of mineral ultrafine grains from washing water of coal processing or from coal sludge |
| GB2136015A (en) * | 1983-03-11 | 1984-09-12 | Sentrachem Ltd | Collector for flotation of coal and other carbonaceous material |
| US5238629A (en) * | 1991-08-09 | 1993-08-24 | Adtech, Inc. Of Illinois | Process of coal agglomeration |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CA1051827A (en) * | 1975-03-24 | 1979-04-03 | Clay D. Smith | Sink float apparatus for cleaning coal and methods usable therein which employ halogenated hydrocarbon parting liquids |
| US4089776A (en) * | 1976-01-21 | 1978-05-16 | Mcmurray Russell L | Process for the separation of agglomerated carbonaceous particles from associated inorganic materials |
| DE2647554C3 (en) * | 1976-10-21 | 1980-06-19 | Bergwerksverband Gmbh, 4300 Essen | Process for the treatment of coal sludge |
-
1982
- 1982-01-11 CA CA000393881A patent/CA1198704A/en not_active Expired
- 1982-01-12 AU AU79440/82A patent/AU533050B2/en not_active Ceased
- 1982-01-22 GB GB8201922A patent/GB2095284B/en not_active Expired
- 1982-02-24 DE DE19823206562 patent/DE3206562C2/en not_active Expired
Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US9518241B2 (en) | 2010-02-01 | 2016-12-13 | Virginia Tech Intellectual Properties, Inc. | Method of separating and de-watering fine particles |
| US9789492B2 (en) | 2010-02-01 | 2017-10-17 | Virginia Tech Intellectual Properties, Inc. | Cleaning and dewatering fine coal |
| US10457883B2 (en) | 2010-02-01 | 2019-10-29 | Virginia Tech Intellectual Properties, Inc. | Method of separating and de-watering fine particles |
| US10562038B2 (en) | 2010-02-01 | 2020-02-18 | Virginia Tech Intellectual Properties, Inc. | Cleaning and dewatering fine coal |
| US10913912B2 (en) | 2010-02-01 | 2021-02-09 | Virginia Tech Intellectual Properties, Inc. | Methods for separating and dewatering fine particles |
| US11331676B2 (en) | 2010-02-01 | 2022-05-17 | Virginia Tech Intellectual Properties, Inc. | Cleaning and dewatering fine coal |
| WO2013188419A1 (en) | 2012-06-11 | 2013-12-19 | Virginia Tech Intellectual Properties, Inc. | Methods for separating and dewatering fine particles |
Also Published As
| Publication number | Publication date |
|---|---|
| GB2095284B (en) | 1985-01-23 |
| DE3206562A1 (en) | 1982-11-04 |
| GB2095284A (en) | 1982-09-29 |
| DE3206562C2 (en) | 1986-04-30 |
| AU533050B2 (en) | 1983-10-27 |
| AU7944082A (en) | 1982-09-30 |
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