CA1178441A - Process for making fuel slurries of coal in water and product thereof - Google Patents
Process for making fuel slurries of coal in water and product thereofInfo
- Publication number
- CA1178441A CA1178441A CA000387401A CA387401A CA1178441A CA 1178441 A CA1178441 A CA 1178441A CA 000387401 A CA000387401 A CA 000387401A CA 387401 A CA387401 A CA 387401A CA 1178441 A CA1178441 A CA 1178441A
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- Canada
- Prior art keywords
- slurry
- dispersant
- water
- produced
- ultrafine particles
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Classifications
-
- 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
- C10L1/00—Liquid carbonaceous fuels
- C10L1/32—Liquid carbonaceous fuels consisting of coal-oil suspensions or aqueous emulsions or oil emulsions
- C10L1/326—Coal-water suspensions
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- Chemical & Material Sciences (AREA)
- Oil, Petroleum & Natural Gas (AREA)
- Engineering & Computer Science (AREA)
- Chemical Kinetics & Catalysis (AREA)
- General Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Liquid Carbonaceous Fuels (AREA)
- Solid Fuels And Fuel-Associated Substances (AREA)
- Emulsifying, Dispersing, Foam-Producing Or Wetting Agents (AREA)
- Colloid Chemistry (AREA)
Abstract
ABSTRACT
Process for making substantially stable coal-water slurries comprising: (a) admixing: (i) ultrafine coal particles having a maximum size of about 10µm MMD
in an amount comprising about 10 to 50% by weight of the slurry, (ii) larger coal particles within the size range of about 20 to 200µm MMD in an amount sufficient to provide a-desired total coal concentration in the slurry, (iii) water, and, (iv) a minor amount of dispersant consisting essentially of alkaline earth metal salt of organo-sulfonate in which the organic moiety is multi-functional, and (b) subjecting the mixture to high shear at a rate of at least about 100 sec-1. The product of this process can be sufficiently highly loaded to serve as fuel.
Process for making substantially stable coal-water slurries comprising: (a) admixing: (i) ultrafine coal particles having a maximum size of about 10µm MMD
in an amount comprising about 10 to 50% by weight of the slurry, (ii) larger coal particles within the size range of about 20 to 200µm MMD in an amount sufficient to provide a-desired total coal concentration in the slurry, (iii) water, and, (iv) a minor amount of dispersant consisting essentially of alkaline earth metal salt of organo-sulfonate in which the organic moiety is multi-functional, and (b) subjecting the mixture to high shear at a rate of at least about 100 sec-1. The product of this process can be sufficiently highly loaded to serve as fuel.
Description
.11'7~4~1 ~' BACKGROUND
.
A high fuel value coal-water slurry which can be injected directly into a furnace as a combustible fuel, can supplant large quantities of incrRasingly exp~nsive fuel oil pres~ntly being used by utilities, factori~ hips, and other commercial enterprises. Since the inert water vehicle reduces fuel value in terms of BTU/lb, it is desirable to minimize its concentration and maximlze coal concentration for efficient use of the slurry as a fuel.
? High coal content also improves the combustion characteristics -~ 10 of the slurry.
It is important, therefore, that the slurry be loadable with finely-divided coal in amounts as high, for .
example, as about 50% to 70% of the slurry. Desplte such high solids loading, the slurry must be sufficiently fluid to be pumped and sprayed into the furnace. The coal particles ., must also be uniformy dispersed. The fluidity and despersion :, ~
.~ must be stably maintained during storage.
SUMMARY
!/"' Fluid, pourable slurries comprising up to about '~ 20 70% or higher of coal stably dispersed in water are produced ;; by admixing finely-divided coal having a critical distribu-tion of particle sizes, water, and an organic dispersant , in a high shear rate mixer. An inorganic buffer salt may also be added. The term "fluid" as employed in this specification and claims means a slurry which is fluid and pourable both at rest and in motion or a slurry which gels or floculates into a substantially non-pourable , .
composition at rest and becomes pourably fluid with stirring or other appllcation of relatively low shear stress.
. ~.
/t~' Con-trolle~ di~txibu~ion ~E coal par~iel~s sixes is essential for bo~h fluidity and stability. The partial size mixture, necessary for fluidity of the highly loaded slurry, comprises ultrafine (UF) particles having a maximum size of up to about 10~ MMD (mass meclian diameter), preferably about 1~ to 8~ MMD and larger particles (F/C) having a size range of about 20~ to 200~ MMD, pre~erably about 20~ to 150 ; MMD. For stability of the slurry, the UF particles should comprise about 10 to 30~ by wt.of the slurry, preferably about 15 to 25%.
; The actual degree of eoal loading is not critical and will vary wlth the given use and operating equipment.
The concentration of coal successfully incorporated into a ; given slurry varies with such factors as the relative amounts of UF and C/F particles, size of the C/F particles used within the effective range, and the like. In general, percentage v loading increases with increasing C/F size. An organic dispersant is essential to maintain the coal particles in , stable disperson. It has been found that the highly-loaded slurries are very sensitive to the particular type of sur-factant used, especially with respect to fluidity and stor-ageability. The dispersants which have proven to be effective in producing stable fluid mixes are high molecular weight ~- alkaline earth metal (e.g. Ca, Mg) organosulfonates in which the organic moiety is polyfunctional. Molecular weight of the organosulfonate is desirably about 1,000 to about 25,000.
The surfactant is used in minor amount, e.g. about 0.5 to 5 pph of coal, preferably about 1 to 2 pph.
In some cases, particularly at higher coal loadings, `~30 it has been found desirable to add an inorganic, alkali metal ~- (e.g. Na, K) buffer salt to stabilize pH of the slurry in the range of about pH5 to 8, preferably about pH 6 to 7.5.
jr/~ - 2 -.~. .
The salt improv~s a~ing stability, pourabllity an~ hAndllng charact~ristics of -th~ slurry. It may b~ that th~ buffer counteracts potentially adverse effects of acid leachates from the coal. The salt, such as sodium or potassium phosphate or carbonate, including their acid salts is used in minor amounts sufficient to provide the desired pH, e.g.
about 0.1 to 2% based on the water. The inorganic salts also serve to reduce gaseous sulfur pollutants by forming non-gaseous sulfur compounds.
The ultrafine and larger F/C coal particles, water, dispersant, and inorganic salt components are mixed - in a blender or other mixing device which can deliver high shear rates. ~igh shear mixing, e.g. at shear rates of at least about 100 sec 1, preferably at least about 500 sec 1, is essential for producing a stable slurry free from substantial sedimentation. r~ he use of high shear mixing and the dis-persant appears to have a synergistic effect. Dispersant ; with low shear mixing results in an extremely viscous, non-pourable slurry, while high shear mixing without dispersant produces a slurry which is unstable towards settling. With both dispersant and high shear mixing a fluid, pourable, stable slurry can be obtained.
The slurries are viscous, fluid dispersions which can generally be characterized as thi-xotropic or Bingham fluids having a yield point. The terms "thixotropicl' and "Bingham fluids" are employed herein in accordance with their currently precise and accepted definitions as given, for example, in Ronald Darby, Viscoelastic Fluids, Marcel Dekker, Inc. 1976, pp. 61, 6~, and 64. The term "thixotropic" refers to a fluid which exhibits a reversible decrease in viscosity with time at a constant shear rate. The term "Bingham fluid"
refers to a fluid which does not flow under yield stresses :.
jr/
.li~7t~
below a certaln yi~ld value or ylcld polnt. Under shaar strosscs above the yleld polnt, lt exhiblts fluld flow, wlth the shear stress belng a substantially linear funct~on of the shear rate. In some cases, the slurrles may gel or flocculate when at rest into a substantlally non-pourable composition but are easlly rendered fluid by stlrrlng or other appllcatlon of relatively low shear stress. They can be stored for conslderable periods of time without excessive settling or sedimentation.
The slurries can be employed as fuels by injection directly into a furnace previously brought up to ignition temperature of the slurry.
The finely divided state of the coal particles improves combustion efficiency. Since the dispersants are organic compounds, they maybe ,- biodeqraded with time. This can readily be prevented by addition of ,, a small amount of biocides.
DETAILED DESCRIPTION
The ultrafine coal particles can be made in any suitable ` device, such as a ball mill or attritor, which is capable of very fine comminution. Preferably, though not essentially, the coal is milled with water so that the UF particles are in water slurry when introduced i into the mixer. Some of the dispersant can be incl~ded, if desired, in the UF milling operation to improve a flow and dispersion characteristics of the UF slurry.
` The required larger size coal particles (20~ to 200~) can be made from crushed coal in a comminuting device such as a hammermill equipped with a grate having appropriately sized openings. Excessively sized coal residue can be used for making the UF particles.
The coal concentrations as used in the specification and in the following examples is on a dried coal basis which normally equals 98.5 by weight of bonedried coal.
The 3.6u MMD UF particles employed in Examples 3-8 were pre-pared in accordance with Example 1 and the UF particles were introducedln the form of the Example 1 aqueous slurry containing a portion of A dm: ~ C~ - 3a -'7~
the diqpersant. The to~al amount o~ dispers~nt glvcn ln th~ Examplos lncludes the portlon lntroduced ln this way.
The 34 ~ MMDand 110 ~MMD partlcles used in the Examples were prepared in accordance with Example 2.
Sedi~entation meansurement, whlch i9 based on Stoke's Law glvlng the relationship between particle size and settling veloclty, .
' was used experimentally in all cases to determine sub-sleve partlcle sizes. The particular sedimentation technique employed is one conventionally known as centrifugal sedimentation. The sedimentometer ` 10 used was the MSA Particle Siæe Analyzer (C.F. Casello & Co. Regent ` House, Britania Walk, London NI). In centrifugal sedimentation, the local acceleration due to gravity, g, is multipled by ~2r/g where ; ~ is rotational velocity and r is radius of rotation. The "two layer"
?j method was used in the experimental procedures. All of the coal powder is initially concentrated in a thin layer floating on top of the suspending water fluid in a centrifuge tube. The fluid is centrifuged at incrementally increasing rotational speeds. The amount of sedimenting powder is measured as a function of time at a specified distance from the surface of the fluid. The cumulative size distribution was determined by plotting the fractional weight settled out against the free-falling Stoke's diameter. Thus sub-sieve particle sizes disclosed and claimed herein were obtained by sedimentation measurement.
Example 1 50% by wt. crushed coal, 1% calcium lignosulfonate ; ~Marasperse C-21) and 49% water were ball milled for 2 hours. The size of the resulting UF coal particles was 3.6 ~ MMD. The UF coal-water slurry was fluid and pourable.
Example 2 A. Crushed coal was comminuted in a hammermill at 3,450 RPM
with a 27 HB grate. The particle size of the product was liO ~ MMD.
:' .
B. Crushed coal was comminuted in a hammermill at 13,SOO RPM
.
wlth a 10 ~B grate. The particle size of the resulting product was 34 ~ MMD.
-- dm: ~ ~Y~ ~ 4 ~
P~
;~,' ' ExamPle 3 ;11 7~
A. 65~ by wt. of coal comprlslng 550 110 ~ MMD coal and 45 3.6 ~ MMD caal, 1.3~ Marasperse C-21 ~calclum llgnln sulfonate Ca content a~ CaO 5.2~, Na cont~nt as Na20 6.1~, Mg content as MgO 0.3~) and 33.7~ water were mixed in a blender at 6,000 RPM at a shear rate of 1,000 sec~l. The resultlng slurry was a paint~ e gel that set lnto a soft gel which was easlly stlrred to a liquld. After 23 days, lt exhlbited no sedlmentationan~ was easlly restirrable to a unlform ~, dispersion having relatively low viscosity - 6.7p.
B. A mix was made identical to A except that 34 ~ MMD particles were substituted for the UF particles. The mix, through initially fluid was unstable. Within 3 days it separated, forming a large supernatant and a highly packed subsidence. It could not be remixed into a uniform, , pourable dispersion.
ç Example 4 A. A 6S% coal slurry comprising 15% 3.6~ MMD and 50% 34 ~ MMD
- particles by ~t. of the slurry, 1.3% Marasperse C-21 and 33.7~ water were mixed in a blender at 6000 RPM. The resulting product was an uniformly dispersed gel which after 12 days in storage exhibited no supernatant, subsidence or sedimentation. The gel was non-pourable at rest and became a pourable fluid with stirring.
B. A mix was made identical to A except that the blender ~as run at a low shear rate of 60 RPM (10 sec~l). The resulting slurry was unstable. Within 4 days it had separated into liquid and aggregated sediment.
Example 5 A. A 65% coal slurry comprising 26% 3.6 ~ MMD particles and 39%
110 ~ MMD particles, 1.3% Marasperse C-21 and 33.7% water were mixed in a blender at 6,000 RPM. The resulting product was a uniformly dispersed slurry which was fluid and pourable and after 10 days was still pourable and substantially free from subsidence or sedimentation.
mix was made identical to A except that the blender ~as run at a low shear rate of 10 sec~l. The resulting slurry was unstable.
; Wlthln 3 days, lt had separated lnto supernatant and aggregated sedlment.
~ dm:t~, _ 5 _ 1~ 41 Examp10 6 A 65S coal slurry was mada Idontlc~l to Ex. 3A oxcopt th~i n~ d15porsani was added, Tho r~sultlng product had tho consls-iorlcy o~ ~ 5tiff gr~aso.
Example 7 A. A 70~ eoal slurry eomprlslng 45.5~ îlO~IMM~ partlelos anl 2ti.5~ ~.6~1 MMD partleles, 1.4~ Marasperso C-21, and 2a.6~ watar solutlon lluf10red to p~i7 by 0.15% Na2tlP04 addad In tho blendor was mlxad at 6,000 ~PM Tho resultlng slurry has an EOM vlscoslty of 1.4~ Kp, Is fluld and pourablo.
After 7 days In storage it exhlbltod no supornatant liquid, sottling or aggregaiion.
B. A m1x was made identleal to A except that phosphate salt was not added. The resulting slurry set up Into a stlff non-pourable mass wlthln 3 days.
C. A mix identical to A, except that the buffer salt was added to the balImill producing the UF partieles, was run in a blonder at the low shear rate of 60 RPM tlO sec ). The slurry was unstable and within 5 days separated into supernatent and stiff aggregated sedlment.
Example 8 A mlx was made identical to Example 4A excopt tha-i- Na2HP04 in amount providing buffered pH7 was added in the blender. The resulting slurr/
was fluld and pourable. Its viscosity was E~M-T-bar 0.92 Kp. It retained Its stability and pourability during stora~e antt after 12 days was free from separation.
Example 9 A. 30 w-t~ of hammermilled coal flnos (,O~IMMD), 0.3~ Marasperse C-21 ~I pph coal), and 69.7~ water were milled in an attritor for 30 min. The resulting slurry was very fluid. The UF coal particle size was 3.88tlMMD.
B. A 65 wt~ coal slurry comprislng 50 wt~ 34~MMD coal particles, 15 wt~, 3,88t~D (uslng 50 wt~ of slurry from 9A supra), 2 pph on coal of Marasperse C-21, and the remalnder water, was mlxod in a blender at a shear rate olf 6,000 RPM (1000 soc 1). Tl-e product was a llniformly-disper;ed, pourable slurry. Aftor 56 days the slurry was a stable, soft, non-pourable gel reo from settllng or sodlmolltation. Thoro was a very sl;ght super supornatant. Probably eausod by wator eval)oratlon arld con(lensatlon ol) the surfaco. The thlxotroplc gel became oaslly pour-al)lo wlth 511~h~ stlrrlng.
At rest It returnod to a stable non-pourabl- stuto wlllln a short time.
, 11'71~4~
I\ftor 61 days It ro-alnod 11~ blo cll~r;~cl~rlnllc~ r sovor~ll st I r rl nqs i o pou rablll-y.
C. A slurry slmllar to 9B was preparod uxcopt tlla~ tho mlx was bufforod to pil7 by the addition of Na2HP04. The producl was a unlformly-dTsperscd fluld slurry of relatlvely low vlscoslty. Aflor 5i clays tlle slurry was a weak, non pourable gel froe from sel-llng or so~imelltatlon. A; In 9B
thero was a vory sllght fibor suporna-ani-. Wilh slight stlrrlng, It -,ecam~
very fluid and pourable it was stlll stablo an(l pourablo after 2~i llours and, although somo what more viscous, rctalnod its stabil7ty and pourablllty 5 days after the Initlal stirrlng.
Example 3 demonstraies the need for the UF particles In controlled size distributlon to impart stabili1y. Examples ~ ani 5 51l0W the neod for high shear rate mlxing. Examples 6 shows the Importance of ihe dlspersant.
Example 7 Illustrates the improvemeni made In a highly-loaded 70t slurry by use of an inorganic buffer salt and the ddverse effect of lo~ shaar mlxlng. Example 8 shows that the use of the pH buffer salt maintained the slurry In a stable fluid conditlon. Example 9 shows that the buffor salt Improved aging and its user and handling charact~ristlcs.
The stable, fluid coal-water slurries are eff7cient and considerably lower cost alternatives to fuel oil. Their flame temp~ratures and hoatlng values compare vary favorably with fuel oil, as is shown In the following Tables:
TABLE I
ADIABATIC FLN~E TEMPERATURE AT 20% EXCESS AIR*
6 Fusl Oil 3095F
70% coal-water slurry 3089F
65% coal-water slurry 3028F
* In a typical furnace HEATING ~ALUE IN BTU/lb OF COMBUSTION PIOBUClS
~ 6 fuel oTI 991.0 70t Coal-water slurry 983.3 65~ coal-water slurry 975.5 The cost of the coal~waier slurrles Inclulling procosslng Is aho~ 2 that of # G fuol oll at prosen-i- prlces.
.
`- .11'7~441 T~l~lE I I I
COST PER M I LL I ON BTU
~ 6 fuel oll S 4.~1 70% coal-watcr slurry S 2.2 65% coal-water slurry S 2.3~1 ,~
~UPPL,EMI.N'r~RY PISCI,~URI~
~ . . _ _ _ . _ . ~.. _ .
With reference to pag~ 2, linc 9 of the m~in disclosure, it has now been Eound tllat ~he r~nge of 10 to 30% by wt. of UF particles in th~ slurry c~n in~act bc 10 to 50~ by wt. withou~ aEFeckinq -~he ~abilit~. ~ho 10 to 30% range being preferable and the 15 to 25% range being more preferable.
The following examples illustrate this finding.
Exam~le 10 -The ultrafine 3.6~ MMD coal component was made in accordance with Example 1. ~ 110~ MMD coal component was prepared as in Example 2.
A 65~ coal slurry comprising 32.5% 3.6~ MMD and 32.5% 110~ ~MD coal particles by wt.of the slurry, 0.65%
Marasperse C-21, and 34.35% water, was prepared in a high speed blender at 6000 RPM (shear rate approximately 1000 sec 1). The resulting slurry was a soft thixotropic gel with a yield point of 49 dynes/cm2. With light stirring to overcome the yield point, the slurry was fluid and pourable. It had a Brookfield viscosity of 1,440 cp at 60 RPM. After 14 days the slurry was still substantially uniformly dispersed. It had a slight surpernatant, was free of hard-~acked sediment, and could easily be stirred to uniformity and pourability.
ExamPle 11 .: .
The 3.6~ ~D ultrafine coal component was made ~, in accordance with Examvle 1, except that 1% Lomar UDG, a calcium naphthalene sulfonate containing 11.5% Ca as CaS04, was substituted for the Marasperse C-21. A llOy MMD
coal component was prepared as in Example 2.
A 65% coal slurry, comprising 32~5% 3.6~ ~D
and 32.5~ 110~ ~D coal particles by wt. of the slurry, - ~ - 9 il'7l~4~1 0.65% Lomar Ul~G, and 3~.~5~ wakcr, w~ pr~pnx~d i.n cl high speed blendcr a-~ 6000 RPM. rrhe resulting slurry was a soft thixotropic gel with a yield point of 30 dynes/cm2. With light stirring to overcome the yield point, the slurry was ~luid and pourabl~. It had a Brookfield viscosity of 1,915 cp at 60 RP~. After 14 days, the slurry was still substantially uniformly dispersed.
It had a slight supernatant, was free of hard-packed sediment, and could easily be stirred to uniformity and pourability.
Example 12 The ultrafine 3.6~ ~lD coal com~onent was prepared by mixing 60 wt% coal with 0.6% Marsasperse C-?l, 0.28% Na2HPO4, and 39.12% water and ball milling for 2 hours as in Example 1. The ~hosphate buffer salt was included to facilitate the grinding. A 110~ MMD coal fraction was prepared b~ hammer-milling as in Example 2.
,~ A 65% coal slurry com~rising 50% 3.6~ D and 15% 110~ MMD coal particles by of the slurry, Marasperse C-21 0.65%, 0.23% Na2HP04, and 34.12% water was prepared in a high speed blender at 6000 RPM. The resulting slurry was a uniformly dispersed thixotrovic gel after 5 days which became fluid and pourable with light stirring.
';
'.~
,: -- 10 --ms/ ~!~` J
.
A high fuel value coal-water slurry which can be injected directly into a furnace as a combustible fuel, can supplant large quantities of incrRasingly exp~nsive fuel oil pres~ntly being used by utilities, factori~ hips, and other commercial enterprises. Since the inert water vehicle reduces fuel value in terms of BTU/lb, it is desirable to minimize its concentration and maximlze coal concentration for efficient use of the slurry as a fuel.
? High coal content also improves the combustion characteristics -~ 10 of the slurry.
It is important, therefore, that the slurry be loadable with finely-divided coal in amounts as high, for .
example, as about 50% to 70% of the slurry. Desplte such high solids loading, the slurry must be sufficiently fluid to be pumped and sprayed into the furnace. The coal particles ., must also be uniformy dispersed. The fluidity and despersion :, ~
.~ must be stably maintained during storage.
SUMMARY
!/"' Fluid, pourable slurries comprising up to about '~ 20 70% or higher of coal stably dispersed in water are produced ;; by admixing finely-divided coal having a critical distribu-tion of particle sizes, water, and an organic dispersant , in a high shear rate mixer. An inorganic buffer salt may also be added. The term "fluid" as employed in this specification and claims means a slurry which is fluid and pourable both at rest and in motion or a slurry which gels or floculates into a substantially non-pourable , .
composition at rest and becomes pourably fluid with stirring or other appllcation of relatively low shear stress.
. ~.
/t~' Con-trolle~ di~txibu~ion ~E coal par~iel~s sixes is essential for bo~h fluidity and stability. The partial size mixture, necessary for fluidity of the highly loaded slurry, comprises ultrafine (UF) particles having a maximum size of up to about 10~ MMD (mass meclian diameter), preferably about 1~ to 8~ MMD and larger particles (F/C) having a size range of about 20~ to 200~ MMD, pre~erably about 20~ to 150 ; MMD. For stability of the slurry, the UF particles should comprise about 10 to 30~ by wt.of the slurry, preferably about 15 to 25%.
; The actual degree of eoal loading is not critical and will vary wlth the given use and operating equipment.
The concentration of coal successfully incorporated into a ; given slurry varies with such factors as the relative amounts of UF and C/F particles, size of the C/F particles used within the effective range, and the like. In general, percentage v loading increases with increasing C/F size. An organic dispersant is essential to maintain the coal particles in , stable disperson. It has been found that the highly-loaded slurries are very sensitive to the particular type of sur-factant used, especially with respect to fluidity and stor-ageability. The dispersants which have proven to be effective in producing stable fluid mixes are high molecular weight ~- alkaline earth metal (e.g. Ca, Mg) organosulfonates in which the organic moiety is polyfunctional. Molecular weight of the organosulfonate is desirably about 1,000 to about 25,000.
The surfactant is used in minor amount, e.g. about 0.5 to 5 pph of coal, preferably about 1 to 2 pph.
In some cases, particularly at higher coal loadings, `~30 it has been found desirable to add an inorganic, alkali metal ~- (e.g. Na, K) buffer salt to stabilize pH of the slurry in the range of about pH5 to 8, preferably about pH 6 to 7.5.
jr/~ - 2 -.~. .
The salt improv~s a~ing stability, pourabllity an~ hAndllng charact~ristics of -th~ slurry. It may b~ that th~ buffer counteracts potentially adverse effects of acid leachates from the coal. The salt, such as sodium or potassium phosphate or carbonate, including their acid salts is used in minor amounts sufficient to provide the desired pH, e.g.
about 0.1 to 2% based on the water. The inorganic salts also serve to reduce gaseous sulfur pollutants by forming non-gaseous sulfur compounds.
The ultrafine and larger F/C coal particles, water, dispersant, and inorganic salt components are mixed - in a blender or other mixing device which can deliver high shear rates. ~igh shear mixing, e.g. at shear rates of at least about 100 sec 1, preferably at least about 500 sec 1, is essential for producing a stable slurry free from substantial sedimentation. r~ he use of high shear mixing and the dis-persant appears to have a synergistic effect. Dispersant ; with low shear mixing results in an extremely viscous, non-pourable slurry, while high shear mixing without dispersant produces a slurry which is unstable towards settling. With both dispersant and high shear mixing a fluid, pourable, stable slurry can be obtained.
The slurries are viscous, fluid dispersions which can generally be characterized as thi-xotropic or Bingham fluids having a yield point. The terms "thixotropicl' and "Bingham fluids" are employed herein in accordance with their currently precise and accepted definitions as given, for example, in Ronald Darby, Viscoelastic Fluids, Marcel Dekker, Inc. 1976, pp. 61, 6~, and 64. The term "thixotropic" refers to a fluid which exhibits a reversible decrease in viscosity with time at a constant shear rate. The term "Bingham fluid"
refers to a fluid which does not flow under yield stresses :.
jr/
.li~7t~
below a certaln yi~ld value or ylcld polnt. Under shaar strosscs above the yleld polnt, lt exhiblts fluld flow, wlth the shear stress belng a substantially linear funct~on of the shear rate. In some cases, the slurrles may gel or flocculate when at rest into a substantlally non-pourable composition but are easlly rendered fluid by stlrrlng or other appllcatlon of relatively low shear stress. They can be stored for conslderable periods of time without excessive settling or sedimentation.
The slurries can be employed as fuels by injection directly into a furnace previously brought up to ignition temperature of the slurry.
The finely divided state of the coal particles improves combustion efficiency. Since the dispersants are organic compounds, they maybe ,- biodeqraded with time. This can readily be prevented by addition of ,, a small amount of biocides.
DETAILED DESCRIPTION
The ultrafine coal particles can be made in any suitable ` device, such as a ball mill or attritor, which is capable of very fine comminution. Preferably, though not essentially, the coal is milled with water so that the UF particles are in water slurry when introduced i into the mixer. Some of the dispersant can be incl~ded, if desired, in the UF milling operation to improve a flow and dispersion characteristics of the UF slurry.
` The required larger size coal particles (20~ to 200~) can be made from crushed coal in a comminuting device such as a hammermill equipped with a grate having appropriately sized openings. Excessively sized coal residue can be used for making the UF particles.
The coal concentrations as used in the specification and in the following examples is on a dried coal basis which normally equals 98.5 by weight of bonedried coal.
The 3.6u MMD UF particles employed in Examples 3-8 were pre-pared in accordance with Example 1 and the UF particles were introducedln the form of the Example 1 aqueous slurry containing a portion of A dm: ~ C~ - 3a -'7~
the diqpersant. The to~al amount o~ dispers~nt glvcn ln th~ Examplos lncludes the portlon lntroduced ln this way.
The 34 ~ MMDand 110 ~MMD partlcles used in the Examples were prepared in accordance with Example 2.
Sedi~entation meansurement, whlch i9 based on Stoke's Law glvlng the relationship between particle size and settling veloclty, .
' was used experimentally in all cases to determine sub-sleve partlcle sizes. The particular sedimentation technique employed is one conventionally known as centrifugal sedimentation. The sedimentometer ` 10 used was the MSA Particle Siæe Analyzer (C.F. Casello & Co. Regent ` House, Britania Walk, London NI). In centrifugal sedimentation, the local acceleration due to gravity, g, is multipled by ~2r/g where ; ~ is rotational velocity and r is radius of rotation. The "two layer"
?j method was used in the experimental procedures. All of the coal powder is initially concentrated in a thin layer floating on top of the suspending water fluid in a centrifuge tube. The fluid is centrifuged at incrementally increasing rotational speeds. The amount of sedimenting powder is measured as a function of time at a specified distance from the surface of the fluid. The cumulative size distribution was determined by plotting the fractional weight settled out against the free-falling Stoke's diameter. Thus sub-sieve particle sizes disclosed and claimed herein were obtained by sedimentation measurement.
Example 1 50% by wt. crushed coal, 1% calcium lignosulfonate ; ~Marasperse C-21) and 49% water were ball milled for 2 hours. The size of the resulting UF coal particles was 3.6 ~ MMD. The UF coal-water slurry was fluid and pourable.
Example 2 A. Crushed coal was comminuted in a hammermill at 3,450 RPM
with a 27 HB grate. The particle size of the product was liO ~ MMD.
:' .
B. Crushed coal was comminuted in a hammermill at 13,SOO RPM
.
wlth a 10 ~B grate. The particle size of the resulting product was 34 ~ MMD.
-- dm: ~ ~Y~ ~ 4 ~
P~
;~,' ' ExamPle 3 ;11 7~
A. 65~ by wt. of coal comprlslng 550 110 ~ MMD coal and 45 3.6 ~ MMD caal, 1.3~ Marasperse C-21 ~calclum llgnln sulfonate Ca content a~ CaO 5.2~, Na cont~nt as Na20 6.1~, Mg content as MgO 0.3~) and 33.7~ water were mixed in a blender at 6,000 RPM at a shear rate of 1,000 sec~l. The resultlng slurry was a paint~ e gel that set lnto a soft gel which was easlly stlrred to a liquld. After 23 days, lt exhlbited no sedlmentationan~ was easlly restirrable to a unlform ~, dispersion having relatively low viscosity - 6.7p.
B. A mix was made identical to A except that 34 ~ MMD particles were substituted for the UF particles. The mix, through initially fluid was unstable. Within 3 days it separated, forming a large supernatant and a highly packed subsidence. It could not be remixed into a uniform, , pourable dispersion.
ç Example 4 A. A 6S% coal slurry comprising 15% 3.6~ MMD and 50% 34 ~ MMD
- particles by ~t. of the slurry, 1.3% Marasperse C-21 and 33.7~ water were mixed in a blender at 6000 RPM. The resulting product was an uniformly dispersed gel which after 12 days in storage exhibited no supernatant, subsidence or sedimentation. The gel was non-pourable at rest and became a pourable fluid with stirring.
B. A mix was made identical to A except that the blender ~as run at a low shear rate of 60 RPM (10 sec~l). The resulting slurry was unstable. Within 4 days it had separated into liquid and aggregated sediment.
Example 5 A. A 65% coal slurry comprising 26% 3.6 ~ MMD particles and 39%
110 ~ MMD particles, 1.3% Marasperse C-21 and 33.7% water were mixed in a blender at 6,000 RPM. The resulting product was a uniformly dispersed slurry which was fluid and pourable and after 10 days was still pourable and substantially free from subsidence or sedimentation.
mix was made identical to A except that the blender ~as run at a low shear rate of 10 sec~l. The resulting slurry was unstable.
; Wlthln 3 days, lt had separated lnto supernatant and aggregated sedlment.
~ dm:t~, _ 5 _ 1~ 41 Examp10 6 A 65S coal slurry was mada Idontlc~l to Ex. 3A oxcopt th~i n~ d15porsani was added, Tho r~sultlng product had tho consls-iorlcy o~ ~ 5tiff gr~aso.
Example 7 A. A 70~ eoal slurry eomprlslng 45.5~ îlO~IMM~ partlelos anl 2ti.5~ ~.6~1 MMD partleles, 1.4~ Marasperso C-21, and 2a.6~ watar solutlon lluf10red to p~i7 by 0.15% Na2tlP04 addad In tho blendor was mlxad at 6,000 ~PM Tho resultlng slurry has an EOM vlscoslty of 1.4~ Kp, Is fluld and pourablo.
After 7 days In storage it exhlbltod no supornatant liquid, sottling or aggregaiion.
B. A m1x was made identleal to A except that phosphate salt was not added. The resulting slurry set up Into a stlff non-pourable mass wlthln 3 days.
C. A mix identical to A, except that the buffer salt was added to the balImill producing the UF partieles, was run in a blonder at the low shear rate of 60 RPM tlO sec ). The slurry was unstable and within 5 days separated into supernatent and stiff aggregated sedlment.
Example 8 A mlx was made identical to Example 4A excopt tha-i- Na2HP04 in amount providing buffered pH7 was added in the blender. The resulting slurr/
was fluld and pourable. Its viscosity was E~M-T-bar 0.92 Kp. It retained Its stability and pourability during stora~e antt after 12 days was free from separation.
Example 9 A. 30 w-t~ of hammermilled coal flnos (,O~IMMD), 0.3~ Marasperse C-21 ~I pph coal), and 69.7~ water were milled in an attritor for 30 min. The resulting slurry was very fluid. The UF coal particle size was 3.88tlMMD.
B. A 65 wt~ coal slurry comprislng 50 wt~ 34~MMD coal particles, 15 wt~, 3,88t~D (uslng 50 wt~ of slurry from 9A supra), 2 pph on coal of Marasperse C-21, and the remalnder water, was mlxod in a blender at a shear rate olf 6,000 RPM (1000 soc 1). Tl-e product was a llniformly-disper;ed, pourable slurry. Aftor 56 days the slurry was a stable, soft, non-pourable gel reo from settllng or sodlmolltation. Thoro was a very sl;ght super supornatant. Probably eausod by wator eval)oratlon arld con(lensatlon ol) the surfaco. The thlxotroplc gel became oaslly pour-al)lo wlth 511~h~ stlrrlng.
At rest It returnod to a stable non-pourabl- stuto wlllln a short time.
, 11'71~4~
I\ftor 61 days It ro-alnod 11~ blo cll~r;~cl~rlnllc~ r sovor~ll st I r rl nqs i o pou rablll-y.
C. A slurry slmllar to 9B was preparod uxcopt tlla~ tho mlx was bufforod to pil7 by the addition of Na2HP04. The producl was a unlformly-dTsperscd fluld slurry of relatlvely low vlscoslty. Aflor 5i clays tlle slurry was a weak, non pourable gel froe from sel-llng or so~imelltatlon. A; In 9B
thero was a vory sllght fibor suporna-ani-. Wilh slight stlrrlng, It -,ecam~
very fluid and pourable it was stlll stablo an(l pourablo after 2~i llours and, although somo what more viscous, rctalnod its stabil7ty and pourablllty 5 days after the Initlal stirrlng.
Example 3 demonstraies the need for the UF particles In controlled size distributlon to impart stabili1y. Examples ~ ani 5 51l0W the neod for high shear rate mlxing. Examples 6 shows the Importance of ihe dlspersant.
Example 7 Illustrates the improvemeni made In a highly-loaded 70t slurry by use of an inorganic buffer salt and the ddverse effect of lo~ shaar mlxlng. Example 8 shows that the use of the pH buffer salt maintained the slurry In a stable fluid conditlon. Example 9 shows that the buffor salt Improved aging and its user and handling charact~ristlcs.
The stable, fluid coal-water slurries are eff7cient and considerably lower cost alternatives to fuel oil. Their flame temp~ratures and hoatlng values compare vary favorably with fuel oil, as is shown In the following Tables:
TABLE I
ADIABATIC FLN~E TEMPERATURE AT 20% EXCESS AIR*
6 Fusl Oil 3095F
70% coal-water slurry 3089F
65% coal-water slurry 3028F
* In a typical furnace HEATING ~ALUE IN BTU/lb OF COMBUSTION PIOBUClS
~ 6 fuel oTI 991.0 70t Coal-water slurry 983.3 65~ coal-water slurry 975.5 The cost of the coal~waier slurrles Inclulling procosslng Is aho~ 2 that of # G fuol oll at prosen-i- prlces.
.
`- .11'7~441 T~l~lE I I I
COST PER M I LL I ON BTU
~ 6 fuel oll S 4.~1 70% coal-watcr slurry S 2.2 65% coal-water slurry S 2.3~1 ,~
~UPPL,EMI.N'r~RY PISCI,~URI~
~ . . _ _ _ . _ . ~.. _ .
With reference to pag~ 2, linc 9 of the m~in disclosure, it has now been Eound tllat ~he r~nge of 10 to 30% by wt. of UF particles in th~ slurry c~n in~act bc 10 to 50~ by wt. withou~ aEFeckinq -~he ~abilit~. ~ho 10 to 30% range being preferable and the 15 to 25% range being more preferable.
The following examples illustrate this finding.
Exam~le 10 -The ultrafine 3.6~ MMD coal component was made in accordance with Example 1. ~ 110~ MMD coal component was prepared as in Example 2.
A 65~ coal slurry comprising 32.5% 3.6~ MMD and 32.5% 110~ ~MD coal particles by wt.of the slurry, 0.65%
Marasperse C-21, and 34.35% water, was prepared in a high speed blender at 6000 RPM (shear rate approximately 1000 sec 1). The resulting slurry was a soft thixotropic gel with a yield point of 49 dynes/cm2. With light stirring to overcome the yield point, the slurry was fluid and pourable. It had a Brookfield viscosity of 1,440 cp at 60 RPM. After 14 days the slurry was still substantially uniformly dispersed. It had a slight surpernatant, was free of hard-~acked sediment, and could easily be stirred to uniformity and pourability.
ExamPle 11 .: .
The 3.6~ ~D ultrafine coal component was made ~, in accordance with Examvle 1, except that 1% Lomar UDG, a calcium naphthalene sulfonate containing 11.5% Ca as CaS04, was substituted for the Marasperse C-21. A llOy MMD
coal component was prepared as in Example 2.
A 65% coal slurry, comprising 32~5% 3.6~ ~D
and 32.5~ 110~ ~D coal particles by wt. of the slurry, - ~ - 9 il'7l~4~1 0.65% Lomar Ul~G, and 3~.~5~ wakcr, w~ pr~pnx~d i.n cl high speed blendcr a-~ 6000 RPM. rrhe resulting slurry was a soft thixotropic gel with a yield point of 30 dynes/cm2. With light stirring to overcome the yield point, the slurry was ~luid and pourabl~. It had a Brookfield viscosity of 1,915 cp at 60 RP~. After 14 days, the slurry was still substantially uniformly dispersed.
It had a slight supernatant, was free of hard-packed sediment, and could easily be stirred to uniformity and pourability.
Example 12 The ultrafine 3.6~ ~lD coal com~onent was prepared by mixing 60 wt% coal with 0.6% Marsasperse C-?l, 0.28% Na2HPO4, and 39.12% water and ball milling for 2 hours as in Example 1. The ~hosphate buffer salt was included to facilitate the grinding. A 110~ MMD coal fraction was prepared b~ hammer-milling as in Example 2.
,~ A 65% coal slurry com~rising 50% 3.6~ D and 15% 110~ MMD coal particles by of the slurry, Marasperse C-21 0.65%, 0.23% Na2HP04, and 34.12% water was prepared in a high speed blender at 6000 RPM. The resulting slurry was a uniformly dispersed thixotrovic gel after 5 days which became fluid and pourable with light stirring.
';
'.~
,: -- 10 --ms/ ~!~` J
Claims
I claim: .
1. Process for making substantially stable coal-water slurries comprising:
a. Admixing:
(i) ultrafine coal particles having a maximum size of about 10µ
MMD in an amount comprising about 10 to 30% by weight of the slurry, (ii) larger coal particles within the size range of about 20 to 200µMMD in an amount sufficient to provide a desired total coal concentration in the slurry, (iii) water, and (iv) a minor amount of dispersant consisting essentially of alkaline earth metal salt of organo-sulfonate in which the organic moiety is multi-functional, and b. subjecting the mixture to high shear at a rate of at least about 100 sec-1.
2. Process of claim 1 in which an inorganic alkali metal buffer salt is added to maintain pH in the range of about 5 to 8.
3. Process of claim 2 in which the buffer salt is an alkali metal phosphate.
4. Process of claim 1 in which:
a. the ultrafine particles are within a size range of about 1 to 8µMMD and comprise about 15 to 25% by wt. of the slurry; and b. the larger coal particles are within a size range of about 20 to 150µMMD.
5. The process of claim 2 in which:
a. the ultrafine particles are within a size range of about I to 8µMMD and comprise about 15 to 25% by wt. of the slurry; and b. the larger coal particles are within d size range of about 20 to 150µMMD.
6. The process of claim 3 in which:
a. the ultrafine particles are within a size range of about 1 to 8µMMD and comprise about 15 to 25% by wt. of the slurry; and b. the larger coal particles are within a size range of about 20 to 150µMMD.
7, The process of claim 1 in which the dispersant is calcium ligno-sulfonate.
8. The process of claim 2 in which the dispersant is calcium ligno-sulfonate.
9. The process of claim 3 in which the dispersant is calcium ligno-sulfonate.
10. The process of claim 4 in which the dispersant is calcium ligno-sulfonate.
11. The process of claim 5 in which the dispersant is calcium ligno-sulfonate.
12. The process of claim 6 in which the dispersant is calcium lignosulfonate.
13. The process of claim 1 in which the minimum shear rate is about 500 sec-1.
14. The process of claim 2 in which the minimum shear rate is about 500 sec-1.
15. The process of claim 3 in which the minimum shear rate is about 500 sec-1.
16. The process of claim 4 in which the minimum shear rate is about 500 sec-1.
17. The process of claim 5 in which the minimum shear rate is about 500 sec-1.
18. The process of claim 6 in which the minimum shear rate is about 500 sec-1.
19. The process of claim 7 in which the minimum shear rate is about 500 sec-1.
20. The process of claim 8 in which the minimum shear rate is about 500 sec-1.
21 The process of claim 9 in which the minimum shear rate is about 500 sec-1.
22. The process of claim 10 in which the minimum shear rate is about 500 sec-1.
23. The process of claim 11 in which the minimum shear rate is about 500 sec-1.
24. The process of claim 12 in which the minimum shear rate is about 500 sec-1.
25. The process of claim 1 in which the ultrafino particles are produced in the presence of water and at least a portion of the dispersant.
26. The process of claim 2 in which the ultrafine particles are produced in the presence of water and at least a portion of the dispersant.
27. The process of claim 3 in which the ultrafine particles are produced in the presence of water and at least a portion of the dispersant.
28. The process of claim 4 in which the ultrafine particles are produced in the presence of water and at least a portion of the dispersant.
29. The process of claim 5 in which the ultrafine particles are produced in the presence of water and at least a portion of the dispersant.
30. The process of claim 6 in which the ultrafine particles are produced in the presence of water and at least a portion of the dispersant.
31. The process of claim 7 in which the ultrafine particles are produced in the presence of water and at least a portion of the dispersant.
32. The process of claim 8 in which the ultrafine particles are produced in the presence of water and at least a portion of the dispersant.
33. The process of claim 9 in which the ultrafine particles are produced in the presence of water and at least a portion of the dispersant.
34. The process of claim 10 in which the ultrafine particles are produced in the presence of water and at least a portion of the dispersant.
35. The process of claim 11 in which the ultrafine particles are produced in the presence of water and at least a portion of the dispersant.
36. The process of claim 12 in which the ultrafine particles are produced in the presence of water and at least a portion of the dispersant.
37. The process of claim 13 in which the ultrafine particles are produced in the presence of water and at least a portion of the dispersant.
38. The process of claim 14 in which the ultrafine particles are produced in the presence of water and at least a portion of the dispersant.
39. The process of claim 15 in which the ultrafine particles are produced in the presence of water and at least a portion of the dispersant.
40. The process of claim 16 in which the ultrafine particles are produced in the presence of water and at least a portion of the dispersant.
41. The process of claim 17 in which the ultrafine particles are produced in the presence of water and at least a portion of the dispersant.
42. The process of claim 18 in which the ultrafine particles are produced in the presence of water and at least a portion of the dispersant.
43. The process of claim 19 in which the ultrafine particles are produced in the presence of water and at least a portion of the dispersant.
44. The process of claim 20 in which the ultrafine particles are produced in the presence of water and at least a portion of the dispersant.
45. The process of claim 21 in which the ultrafine particles are produced in the presence of water and at least a portion of the dispersant.
46. The process of claim 22 in which the ultrafine particles are produced in the presence of water and at least a portion of the dispersant.
47. The process of claim 23 in which the ultrafine particles are produced in the presence of water and at least a portion of the dispersant.
48. The process of claim 24 in which the ultrafine particles are produced in the presence of water and at least a portion of the dispersant.
49. A coal-water slurry which comprises:
a. ultrafine coal particles having a maximum size of about 10µMMD, in an amount comprising about 10 to 30% by weight of slurry.
b. larger coal particles within the size range of about 20 to 200 MMD in an amount sufficient to provide a desired total coal concentration in the slurry;
e. water; and d. a minor amount of a despersant consisting es-sentially of an alkaline earth metal organo sulfonate in which the organic moiety is multi-functional.
50. The slurry of claim 49 in which:
a. the ultrafine particles are within a size range of about 1 to 8µMMD, and b. the larger particles are within the size range of about 20 to 150µMMD.
51. The slurry of claim 49 in which the dispersant is calcium lignosulfonate.
52. The slurry of claim 50 in which the dispersant is calcium lignosulfonate.
53. The slurry of claim 49 which is buffered to a pH of about 5 to 8 by means of an inorganic alkali metal buffer salt.
54. The slurry of claim 50 which is buffered to pH of about 5 to 8 by means of an inorganic alkali metal buffer salt.
55. The slurry of claim 51 which is buffered to a pH of about 5 to 8 by means of an inorganic alkali metal buffer salt.
56. The slurry of claim 52 which is buffered to a pH of about 5 to 8 by means of an inorganic alkali metal buffer salt.
57. The slurry of claim 53 in which the buffer salt is a phosphate.
58. The slurry of claim 54 in which the buffer salt is a phosphate.
59. The slurry of claim 55 in which the buffer salt is a phosphate.
60. The slurry of claim 56 in which the buffer salt is a phosphate.
61. The slurry of claim 49 in which the slurry is a substantially thixotropic or Bingham fluid.
62. The slurry of claim 50 in which the slurry is a substantially thixotropic or Bingham fluid.
63. The slurry of claim 51 in which the slurry is a substantially thixotropic or Bingham fluid.
64. The slurry of claim 53 in which the slurry is a substantially thixotropic or Bingham fluid.
65. The slurry of claim 55 in which the slurry is a substantially thixotropic or Bingham fluid.
66. The slurry of claim 57 in which the slurry is a substantially thixotropic or Bingham fluid.
67. The slurry of claim 59 in which the slurry is a substantially thixotropic or Bingham fluid.
68. The process of claim 1 in which sub-sieve particle sizes are defined in terms of those obtainable by sedimentation measurement employing Stoke's Law.
69. The slurry of claim 49 in which sub-sieve particle sizes are defined in terms of those obtainable by sedimentation measurement employing Stoke's Law.
70. The slurry of claim 61 in which sub-sieve particle sizes are defined in terms of those obtainable by sedimentation measurement employing Stoke's Law.
CLAIMS SUPPORTED BY THE SUPPLEMENTARY DISCLOSURE
71. Process for making substantially stable coal-water slurries comprising:
a. Admixing:
(i) ultrafine coal particles having a maximum size of about 10µm MMD
in an amount comprising about 10 to 50% by weight of the slurry, (ii) larger coal particles within the size range of about 20 to 200µm MMD in an amount sufficient to provide a desired total coal concentration in the slurry, (iii) water, and, (iv) a minor amount of dispersant consisting essentially of alkaline earth metal salt of organo-sulfonate in which the organic moiety is multi-functional, and b. subjecting the mixture to high shear at a rate of at least about 100 sec-1.
72. Process of claim 71 in which an inorganic buffer is added to maintain pH in the range of about 5 to 8.
73. Process of claim 72 in which the buffer is an alkali metal phosphate.
74. Process of claim 71 in which:
a. The ultrafine particles are within the size range of about 1 to 8µm MMD; and b. the larger coal particles are within a size range of about 20 to 150µm MMD.
75. The process of claim 71 in which the dispersant is calcium lignosulfonate.
76. The process of claim 72 in which the dispersant is calcium lignosulfonate.
77. The process of claim 74 in which the dispersant is calcium lignosulfonate.
78. The process of claim 71 in which the minimum shear rate is about 500 sec-1.79. The process of claim 72 in which the minimum shear rate is about 500 sec-1.80. The process of claim 74 in which the minimum shear rate is about 500 sec-1.81. The process of claim 75 in which the minimum shear rate is about 500 sec-1.82. The process of claim 76 in which the minimum shear rate is about 500 sec-1.83. The process of claim 77 in which the minimum shear rate is about 500 sec-1.84. The process of claim 71 in which the ultrafine particles are produced in the presence of water and at least a portion of the dispersant.
85. The process of claim 74 in which the ultrafine particles are produced in the presence of water and at least a portion of the dispersant.
86. The process of claim 75 in which the ultrafine particles are produced in the presence of water and at least a portion of the dispersant.
87. The process of claim 77 in which the ultrafine particles are produced in the presence of water and at least a portion of the dispersant.
88. The process of claim 80 in which the ultrafine particles are produced in the presence of water and at least a portion of the dispersant.
89. The process of claim 81 in which the ultrafine particles are produced in the presence of water and at least a portion of the dispersant.
90. The process of claim 83 in which the ultrafine particles are produced in the presence of water and at least a portion of the dispersant.
91. A coal-water slurry which comprises:
a. ultrafine coal particles having a maximum size of about 10µm MMD, in an amount comprising about 10 to 50% by weight of slurry;
b. larger coal particles within the size range of about 20 to 200µm MMD
in an amount sufficient to provide a desired total coal concentration in the slurry;
c. water; and d. a minor amount of a dispersant consisting essentially of an alkaline earth metal organo-sulfonate in which the organic moiety is multi-functional.
92. The slurry of claim 91 in which:
a. the ultrafine particles are within a size range of about 1 to 8µm MMD, and, b. the larger particles are within the size range of about 20 to 150µ MMD.
93. The slurry of claim 91 in which the dispersant is calcium lignosulfonate.
94. The slurry of claim 92 in which the dispersant is calcium lignosulfonate.
95. The slurry of claim 91 which is buffered to a pH of about 5 to 8 by an inorganic buffer.
96. The slurry of claim 95 in which the buffer is an alkali metal phosphate.
97. The slurry of claim 91 in which the slurry is a substantially thixotropic or Bingham fluid.
98. The slurry of claim 92 in which the slurry is a substantially thixotropic or Bingham fluid.
99. The slurry of claim 93 in which the slurry is a substantially thixotropic or Bingham fluid.
100. The process of claim 71 in which sub-sieve particle sizes are defined in terms of those obtainable by sedimentation measurement employing Stoke's Law.
101. The process of claim 74 in which sub-sieve particle sizes are defined in terms of those obtainable by sedimentation measurement employing Stoke's Law.
102. The process of claim 77 in which sub-sieve particle sizes are defined in terms of those obtainable by sedimentation measurement employing Stoke's Law.
103. The process of claim 78 in which sub-sieve particle sizes are defined in terms of those obtainable by sedimentation measurement employing Stoke's Law.
104. The process of claim 80 in which sub-sieve particle sizes are defined In terms of those obtainable by sedimentation measurement employing Stoke's Law 105. The slurry of claim 91 in which sub-sieve particle sizes are defined in terms of those obtainable by sedimentation measurement employing Stoke's Law.
106. The slurry of claim 92 in which sub-sieve particle sizes are defined in terms of those obtainable by sedimentation measurement employing Stoke's Law.
107. The slurry of claim 97 in which sub-sieve particle sizes are defined in terms of those obtainable by sedimentation measurement employing Stoke's Law.
108. The slurry of claim 98 in which sub-sieve particle sizes are defined in terms of those obtainable by sedimentation measurement employing Stoke's Law.
1. Process for making substantially stable coal-water slurries comprising:
a. Admixing:
(i) ultrafine coal particles having a maximum size of about 10µ
MMD in an amount comprising about 10 to 30% by weight of the slurry, (ii) larger coal particles within the size range of about 20 to 200µMMD in an amount sufficient to provide a desired total coal concentration in the slurry, (iii) water, and (iv) a minor amount of dispersant consisting essentially of alkaline earth metal salt of organo-sulfonate in which the organic moiety is multi-functional, and b. subjecting the mixture to high shear at a rate of at least about 100 sec-1.
2. Process of claim 1 in which an inorganic alkali metal buffer salt is added to maintain pH in the range of about 5 to 8.
3. Process of claim 2 in which the buffer salt is an alkali metal phosphate.
4. Process of claim 1 in which:
a. the ultrafine particles are within a size range of about 1 to 8µMMD and comprise about 15 to 25% by wt. of the slurry; and b. the larger coal particles are within a size range of about 20 to 150µMMD.
5. The process of claim 2 in which:
a. the ultrafine particles are within a size range of about I to 8µMMD and comprise about 15 to 25% by wt. of the slurry; and b. the larger coal particles are within d size range of about 20 to 150µMMD.
6. The process of claim 3 in which:
a. the ultrafine particles are within a size range of about 1 to 8µMMD and comprise about 15 to 25% by wt. of the slurry; and b. the larger coal particles are within a size range of about 20 to 150µMMD.
7, The process of claim 1 in which the dispersant is calcium ligno-sulfonate.
8. The process of claim 2 in which the dispersant is calcium ligno-sulfonate.
9. The process of claim 3 in which the dispersant is calcium ligno-sulfonate.
10. The process of claim 4 in which the dispersant is calcium ligno-sulfonate.
11. The process of claim 5 in which the dispersant is calcium ligno-sulfonate.
12. The process of claim 6 in which the dispersant is calcium lignosulfonate.
13. The process of claim 1 in which the minimum shear rate is about 500 sec-1.
14. The process of claim 2 in which the minimum shear rate is about 500 sec-1.
15. The process of claim 3 in which the minimum shear rate is about 500 sec-1.
16. The process of claim 4 in which the minimum shear rate is about 500 sec-1.
17. The process of claim 5 in which the minimum shear rate is about 500 sec-1.
18. The process of claim 6 in which the minimum shear rate is about 500 sec-1.
19. The process of claim 7 in which the minimum shear rate is about 500 sec-1.
20. The process of claim 8 in which the minimum shear rate is about 500 sec-1.
21 The process of claim 9 in which the minimum shear rate is about 500 sec-1.
22. The process of claim 10 in which the minimum shear rate is about 500 sec-1.
23. The process of claim 11 in which the minimum shear rate is about 500 sec-1.
24. The process of claim 12 in which the minimum shear rate is about 500 sec-1.
25. The process of claim 1 in which the ultrafino particles are produced in the presence of water and at least a portion of the dispersant.
26. The process of claim 2 in which the ultrafine particles are produced in the presence of water and at least a portion of the dispersant.
27. The process of claim 3 in which the ultrafine particles are produced in the presence of water and at least a portion of the dispersant.
28. The process of claim 4 in which the ultrafine particles are produced in the presence of water and at least a portion of the dispersant.
29. The process of claim 5 in which the ultrafine particles are produced in the presence of water and at least a portion of the dispersant.
30. The process of claim 6 in which the ultrafine particles are produced in the presence of water and at least a portion of the dispersant.
31. The process of claim 7 in which the ultrafine particles are produced in the presence of water and at least a portion of the dispersant.
32. The process of claim 8 in which the ultrafine particles are produced in the presence of water and at least a portion of the dispersant.
33. The process of claim 9 in which the ultrafine particles are produced in the presence of water and at least a portion of the dispersant.
34. The process of claim 10 in which the ultrafine particles are produced in the presence of water and at least a portion of the dispersant.
35. The process of claim 11 in which the ultrafine particles are produced in the presence of water and at least a portion of the dispersant.
36. The process of claim 12 in which the ultrafine particles are produced in the presence of water and at least a portion of the dispersant.
37. The process of claim 13 in which the ultrafine particles are produced in the presence of water and at least a portion of the dispersant.
38. The process of claim 14 in which the ultrafine particles are produced in the presence of water and at least a portion of the dispersant.
39. The process of claim 15 in which the ultrafine particles are produced in the presence of water and at least a portion of the dispersant.
40. The process of claim 16 in which the ultrafine particles are produced in the presence of water and at least a portion of the dispersant.
41. The process of claim 17 in which the ultrafine particles are produced in the presence of water and at least a portion of the dispersant.
42. The process of claim 18 in which the ultrafine particles are produced in the presence of water and at least a portion of the dispersant.
43. The process of claim 19 in which the ultrafine particles are produced in the presence of water and at least a portion of the dispersant.
44. The process of claim 20 in which the ultrafine particles are produced in the presence of water and at least a portion of the dispersant.
45. The process of claim 21 in which the ultrafine particles are produced in the presence of water and at least a portion of the dispersant.
46. The process of claim 22 in which the ultrafine particles are produced in the presence of water and at least a portion of the dispersant.
47. The process of claim 23 in which the ultrafine particles are produced in the presence of water and at least a portion of the dispersant.
48. The process of claim 24 in which the ultrafine particles are produced in the presence of water and at least a portion of the dispersant.
49. A coal-water slurry which comprises:
a. ultrafine coal particles having a maximum size of about 10µMMD, in an amount comprising about 10 to 30% by weight of slurry.
b. larger coal particles within the size range of about 20 to 200 MMD in an amount sufficient to provide a desired total coal concentration in the slurry;
e. water; and d. a minor amount of a despersant consisting es-sentially of an alkaline earth metal organo sulfonate in which the organic moiety is multi-functional.
50. The slurry of claim 49 in which:
a. the ultrafine particles are within a size range of about 1 to 8µMMD, and b. the larger particles are within the size range of about 20 to 150µMMD.
51. The slurry of claim 49 in which the dispersant is calcium lignosulfonate.
52. The slurry of claim 50 in which the dispersant is calcium lignosulfonate.
53. The slurry of claim 49 which is buffered to a pH of about 5 to 8 by means of an inorganic alkali metal buffer salt.
54. The slurry of claim 50 which is buffered to pH of about 5 to 8 by means of an inorganic alkali metal buffer salt.
55. The slurry of claim 51 which is buffered to a pH of about 5 to 8 by means of an inorganic alkali metal buffer salt.
56. The slurry of claim 52 which is buffered to a pH of about 5 to 8 by means of an inorganic alkali metal buffer salt.
57. The slurry of claim 53 in which the buffer salt is a phosphate.
58. The slurry of claim 54 in which the buffer salt is a phosphate.
59. The slurry of claim 55 in which the buffer salt is a phosphate.
60. The slurry of claim 56 in which the buffer salt is a phosphate.
61. The slurry of claim 49 in which the slurry is a substantially thixotropic or Bingham fluid.
62. The slurry of claim 50 in which the slurry is a substantially thixotropic or Bingham fluid.
63. The slurry of claim 51 in which the slurry is a substantially thixotropic or Bingham fluid.
64. The slurry of claim 53 in which the slurry is a substantially thixotropic or Bingham fluid.
65. The slurry of claim 55 in which the slurry is a substantially thixotropic or Bingham fluid.
66. The slurry of claim 57 in which the slurry is a substantially thixotropic or Bingham fluid.
67. The slurry of claim 59 in which the slurry is a substantially thixotropic or Bingham fluid.
68. The process of claim 1 in which sub-sieve particle sizes are defined in terms of those obtainable by sedimentation measurement employing Stoke's Law.
69. The slurry of claim 49 in which sub-sieve particle sizes are defined in terms of those obtainable by sedimentation measurement employing Stoke's Law.
70. The slurry of claim 61 in which sub-sieve particle sizes are defined in terms of those obtainable by sedimentation measurement employing Stoke's Law.
CLAIMS SUPPORTED BY THE SUPPLEMENTARY DISCLOSURE
71. Process for making substantially stable coal-water slurries comprising:
a. Admixing:
(i) ultrafine coal particles having a maximum size of about 10µm MMD
in an amount comprising about 10 to 50% by weight of the slurry, (ii) larger coal particles within the size range of about 20 to 200µm MMD in an amount sufficient to provide a desired total coal concentration in the slurry, (iii) water, and, (iv) a minor amount of dispersant consisting essentially of alkaline earth metal salt of organo-sulfonate in which the organic moiety is multi-functional, and b. subjecting the mixture to high shear at a rate of at least about 100 sec-1.
72. Process of claim 71 in which an inorganic buffer is added to maintain pH in the range of about 5 to 8.
73. Process of claim 72 in which the buffer is an alkali metal phosphate.
74. Process of claim 71 in which:
a. The ultrafine particles are within the size range of about 1 to 8µm MMD; and b. the larger coal particles are within a size range of about 20 to 150µm MMD.
75. The process of claim 71 in which the dispersant is calcium lignosulfonate.
76. The process of claim 72 in which the dispersant is calcium lignosulfonate.
77. The process of claim 74 in which the dispersant is calcium lignosulfonate.
78. The process of claim 71 in which the minimum shear rate is about 500 sec-1.79. The process of claim 72 in which the minimum shear rate is about 500 sec-1.80. The process of claim 74 in which the minimum shear rate is about 500 sec-1.81. The process of claim 75 in which the minimum shear rate is about 500 sec-1.82. The process of claim 76 in which the minimum shear rate is about 500 sec-1.83. The process of claim 77 in which the minimum shear rate is about 500 sec-1.84. The process of claim 71 in which the ultrafine particles are produced in the presence of water and at least a portion of the dispersant.
85. The process of claim 74 in which the ultrafine particles are produced in the presence of water and at least a portion of the dispersant.
86. The process of claim 75 in which the ultrafine particles are produced in the presence of water and at least a portion of the dispersant.
87. The process of claim 77 in which the ultrafine particles are produced in the presence of water and at least a portion of the dispersant.
88. The process of claim 80 in which the ultrafine particles are produced in the presence of water and at least a portion of the dispersant.
89. The process of claim 81 in which the ultrafine particles are produced in the presence of water and at least a portion of the dispersant.
90. The process of claim 83 in which the ultrafine particles are produced in the presence of water and at least a portion of the dispersant.
91. A coal-water slurry which comprises:
a. ultrafine coal particles having a maximum size of about 10µm MMD, in an amount comprising about 10 to 50% by weight of slurry;
b. larger coal particles within the size range of about 20 to 200µm MMD
in an amount sufficient to provide a desired total coal concentration in the slurry;
c. water; and d. a minor amount of a dispersant consisting essentially of an alkaline earth metal organo-sulfonate in which the organic moiety is multi-functional.
92. The slurry of claim 91 in which:
a. the ultrafine particles are within a size range of about 1 to 8µm MMD, and, b. the larger particles are within the size range of about 20 to 150µ MMD.
93. The slurry of claim 91 in which the dispersant is calcium lignosulfonate.
94. The slurry of claim 92 in which the dispersant is calcium lignosulfonate.
95. The slurry of claim 91 which is buffered to a pH of about 5 to 8 by an inorganic buffer.
96. The slurry of claim 95 in which the buffer is an alkali metal phosphate.
97. The slurry of claim 91 in which the slurry is a substantially thixotropic or Bingham fluid.
98. The slurry of claim 92 in which the slurry is a substantially thixotropic or Bingham fluid.
99. The slurry of claim 93 in which the slurry is a substantially thixotropic or Bingham fluid.
100. The process of claim 71 in which sub-sieve particle sizes are defined in terms of those obtainable by sedimentation measurement employing Stoke's Law.
101. The process of claim 74 in which sub-sieve particle sizes are defined in terms of those obtainable by sedimentation measurement employing Stoke's Law.
102. The process of claim 77 in which sub-sieve particle sizes are defined in terms of those obtainable by sedimentation measurement employing Stoke's Law.
103. The process of claim 78 in which sub-sieve particle sizes are defined in terms of those obtainable by sedimentation measurement employing Stoke's Law.
104. The process of claim 80 in which sub-sieve particle sizes are defined In terms of those obtainable by sedimentation measurement employing Stoke's Law 105. The slurry of claim 91 in which sub-sieve particle sizes are defined in terms of those obtainable by sedimentation measurement employing Stoke's Law.
106. The slurry of claim 92 in which sub-sieve particle sizes are defined in terms of those obtainable by sedimentation measurement employing Stoke's Law.
107. The slurry of claim 97 in which sub-sieve particle sizes are defined in terms of those obtainable by sedimentation measurement employing Stoke's Law.
108. The slurry of claim 98 in which sub-sieve particle sizes are defined in terms of those obtainable by sedimentation measurement employing Stoke's Law.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US19785380A | 1980-10-17 | 1980-10-17 | |
| US197,853 | 1980-10-17 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1178441A true CA1178441A (en) | 1984-11-27 |
Family
ID=22731003
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000387401A Expired CA1178441A (en) | 1980-10-17 | 1981-10-06 | Process for making fuel slurries of coal in water and product thereof |
Country Status (8)
| Country | Link |
|---|---|
| EP (1) | EP0050412B1 (en) |
| JP (1) | JPS5796090A (en) |
| AT (1) | ATE11927T1 (en) |
| AU (1) | AU554293B2 (en) |
| CA (1) | CA1178441A (en) |
| DE (1) | DE3169061D1 (en) |
| IL (1) | IL63866A (en) |
| ZA (1) | ZA816150B (en) |
Families Citing this family (26)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4551179A (en) * | 1981-01-29 | 1985-11-05 | The Standard Oil Company | Coal-aqueous mixtures |
| US4441889A (en) * | 1981-01-29 | 1984-04-10 | Gulf & Western Industries, Inc. | Coal-aqueous mixtures |
| IT1211049B (en) * | 1981-05-21 | 1989-09-29 | Snam Progetti | COAL WATER SUSPENSION. |
| GR76426B (en) * | 1981-05-21 | 1984-08-10 | Snam Progetti | |
| JPS5896690A (en) * | 1981-12-03 | 1983-06-08 | Electric Power Dev Co Ltd | Preparation of concentrated coal slurry |
| US4498906A (en) * | 1982-03-22 | 1985-02-12 | Atlantic Research Corporation | Coal-water fuel slurries and process for making |
| NZ202639A (en) * | 1982-03-22 | 1986-03-14 | Atlantic Res Corp | Stable coal-water slurries and a method for their preparation |
| US4504277A (en) * | 1982-04-16 | 1985-03-12 | Atlantic Research Corporation | Coal-water fuel slurries and process for making same |
| SE8202879L (en) * | 1982-05-07 | 1983-11-08 | Carbogel Ab | WATER SLUSHING OF A SOLID FUEL AND KITCHEN AND MEANS OF PREPARING THEREOF |
| EP0094786B1 (en) * | 1982-05-19 | 1987-11-04 | The British Petroleum Company p.l.c. | Mineral slurries |
| GB2121819B (en) * | 1982-06-14 | 1985-03-27 | Smidth & Co As F L | Method of manufacturing a pumpable coal/liquid mixture |
| US4511365A (en) * | 1982-09-10 | 1985-04-16 | Sohio Alternate Energy Development Company | Coal-aqueous mixtures |
| US4722740A (en) * | 1982-09-30 | 1988-02-02 | Oxce Fuel Company | Dispersions of coal in water useful as a fuel |
| FR2538407A1 (en) * | 1982-12-27 | 1984-06-29 | Raffinage Cie Francaise | LIQUID FUEL BASED ON PULVERIZED SOLID FUEL, PETROLEUM RESIDUES AND WATER, ITS PREPARATION PROCESS AND APPLICATION IN BOILERS OR INDUSTRIAL FURNACES |
| AU568660B2 (en) * | 1983-07-05 | 1988-01-07 | Babcock-Hitachi Kabushiki Kaisha | Coal-water slurry |
| GB8319033D0 (en) * | 1983-07-14 | 1983-08-17 | Carbogel Ab | Sulphur capture |
| JPS6058491A (en) * | 1983-09-09 | 1985-04-04 | Electric Power Dev Co Ltd | Stabilizing treatment of aqueous slully of carbon- containing composition |
| JPS6071693A (en) * | 1983-09-29 | 1985-04-23 | Babcock Hitachi Kk | Production of coal-water mixture |
| JPS6136398A (en) * | 1984-07-30 | 1986-02-21 | Babcock Hitachi Kk | Production of highly concentrated coal-water slurry |
| US4810259A (en) * | 1985-09-19 | 1989-03-07 | Oxce Fuel Company | Method to minimize viscosity and improve stability of coal-water fuels |
| DE3707941A1 (en) * | 1987-03-12 | 1988-09-22 | Henkel Kgaa | DISPERSING AGENTS AND THEIR USE IN AQUEOUS CARBON SUSPENSIONS |
| JPH02232296A (en) * | 1989-03-06 | 1990-09-14 | Central Res Inst Of Electric Power Ind | Preparation of coal-water slurry |
| JP2595465B2 (en) * | 1994-04-13 | 1997-04-02 | 英司 池田 | Water / coal blended fuel |
| US20130074396A1 (en) | 2008-06-30 | 2013-03-28 | Gustavo A. Núñez | Nano-dispersions of carbonaceous material in water as the basis of fuel related technologies and methods of making same |
| WO2010039315A2 (en) * | 2008-06-30 | 2010-04-08 | Nano Dispersions Technology, Inc. | Nano-dispersions of coal in water as the basis of fuel related tecfinologies and methods of making same |
| SG10201602735VA (en) * | 2011-04-07 | 2016-05-30 | Nano Dispersions Technology Inc | Nano-dispersions of carbonaceous material in water as the basis of fuel related technologies and methods of making same |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB1522575A (en) * | 1976-06-24 | 1978-08-23 | Texaco Development Corp | Production of solid fuel-water slurries |
| US4261701A (en) * | 1980-01-09 | 1981-04-14 | Gulf Research & Development Company | Uniform coal suspensions and process for preparing same |
-
1981
- 1981-09-04 ZA ZA816150A patent/ZA816150B/en unknown
- 1981-09-14 EP EP81304187A patent/EP0050412B1/en not_active Expired
- 1981-09-14 AT AT81304187T patent/ATE11927T1/en not_active IP Right Cessation
- 1981-09-14 DE DE8181304187T patent/DE3169061D1/en not_active Expired
- 1981-09-17 AU AU75439/81A patent/AU554293B2/en not_active Ceased
- 1981-09-17 IL IL63866A patent/IL63866A/en unknown
- 1981-10-06 CA CA000387401A patent/CA1178441A/en not_active Expired
- 1981-10-17 JP JP56164956A patent/JPS5796090A/en active Pending
Also Published As
| Publication number | Publication date |
|---|---|
| ZA816150B (en) | 1982-09-29 |
| AU554293B2 (en) | 1986-08-14 |
| EP0050412A3 (en) | 1982-08-04 |
| EP0050412B1 (en) | 1985-02-20 |
| DE3169061D1 (en) | 1985-03-28 |
| ATE11927T1 (en) | 1985-03-15 |
| EP0050412A2 (en) | 1982-04-28 |
| IL63866A (en) | 1984-07-31 |
| IL63866A0 (en) | 1981-12-31 |
| JPS5796090A (en) | 1982-06-15 |
| AU7543981A (en) | 1982-04-22 |
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Legal Events
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