CA1240966A - Process for the preparation of a suspension of solids at high concentration - Google Patents
Process for the preparation of a suspension of solids at high concentrationInfo
- Publication number
- CA1240966A CA1240966A CA000474439A CA474439A CA1240966A CA 1240966 A CA1240966 A CA 1240966A CA 000474439 A CA000474439 A CA 000474439A CA 474439 A CA474439 A CA 474439A CA 1240966 A CA1240966 A CA 1240966A
- Authority
- CA
- Canada
- Prior art keywords
- solid
- suspension
- milling
- process according
- water
- 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
-
- 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
Landscapes
- 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)
- Disintegrating Or Milling (AREA)
- Crushing And Grinding (AREA)
- Solid Fuels And Fuel-Associated Substances (AREA)
- Carbon And Carbon Compounds (AREA)
Abstract
"PROCESS FOR THE PREPARATION OF A SUSPENSION OF SOLIDS
AT HIGH CONCENTRATION"
Abstract of the Disclosure A suspension of solids at high concentration, in par-ticular of highly concentrated coal in water, is prepar ed by submitting the solid to be suspended in the liquid to two wet milling operations, preceded by a preliminary grinding (crushing).
The solid granulated up to a maximum size of 6 mm is micronized by wet milling in a first mill, into which it is fed together with water and suspension-stabilizing additives, the weight ratio between the solid and water being comprised within the range of from 35/65 to 60/40, it preferably being 51/49.
The additive content is comprised within the range of from 0.3% to 3% by weight relatively to the solid.
The aqueous suspension containing the solid micronized down to a maximum size of about 20 µm is used as diluent medium in a second mill, into which is fed a charge con stituted by crushed solid and by the above mentioned aqueous suspension, the weight ratio between the above mentioned aqueous suspension and the granulated solid being comprised within the range of from 46/54 to 75/25, it preferably being 51/49.
The milling in the second mill allows a suspension 2.
to be obtained, wherein the average size of the micron-ized solid is substantially unchanged and the product obtained does not require further mixing or water sepa-ration stages in order to obtain the suspension at the desired concentration.
AT HIGH CONCENTRATION"
Abstract of the Disclosure A suspension of solids at high concentration, in par-ticular of highly concentrated coal in water, is prepar ed by submitting the solid to be suspended in the liquid to two wet milling operations, preceded by a preliminary grinding (crushing).
The solid granulated up to a maximum size of 6 mm is micronized by wet milling in a first mill, into which it is fed together with water and suspension-stabilizing additives, the weight ratio between the solid and water being comprised within the range of from 35/65 to 60/40, it preferably being 51/49.
The additive content is comprised within the range of from 0.3% to 3% by weight relatively to the solid.
The aqueous suspension containing the solid micronized down to a maximum size of about 20 µm is used as diluent medium in a second mill, into which is fed a charge con stituted by crushed solid and by the above mentioned aqueous suspension, the weight ratio between the above mentioned aqueous suspension and the granulated solid being comprised within the range of from 46/54 to 75/25, it preferably being 51/49.
The milling in the second mill allows a suspension 2.
to be obtained, wherein the average size of the micron-ized solid is substantially unchanged and the product obtained does not require further mixing or water sepa-ration stages in order to obtain the suspension at the desired concentration.
Description
124~6 ! PROCESS FOR THE PREPARATION OF A SUSPENSION OF A SOLID
The present invention relates to a process for the preparation of a suspension of a solid at a high concentration. More particularly, the present invention relates to a process for the preparation of a suspension of coal in water at a high concentration, and to such a suspension we will mainly refer in the following disclosure.
For the preparation of a suspension of a solid, in ; 10 particular of coal, it is generally necessary to reduce the solid to such dimensions as to make it possible to maintain it stably suspended in the liquid; thls is done by milling.
According to the presently known axt, the milling can he effected either in a single stage or in a plurality of stages, depending whether a continuous range of particle size or a plurality of ranges of particle size (granulometric size) is desired.
In the specific case of coal, lt has been demonstrated that particularly useful are suspensions containing coal of two different granulometric sizes.
Among these, those disclosed in our Frenchlaid-open Patent Application No. 2,506,323 are particularly useful.
In order to obtain the partlcles of coal with two different granulometric sizes, three milling systems 3, may be used: a dry system, a wet system, or a mixed dry-wet system.
The dry systems are highly polluting and require high investment and operating costs and are being more and more frequently superseded by wet systems.
We will therefore mainly deal with the wet milling systems in connection with the preparation of a coal suspension formed by a mixture of coal particles ~i belonging to two different dimensional ranges ~bimodal mixture).
The wet milling system (coal plus water) for the ' .
~, r~
' suspenslons mentloned are aharacteri~ed by a primary mllling of a mixture of about 50% by weight of coal pre-grouna to a maximum slze of 6 mm, and about 50~ by weight of water, whereby a ground fractlon of coarse type ls obtalned; a portlon of this mlxture ls sent to a micronlzer ln order to form a fine fraction (mlcronized coal) and so as to obtain, after the comblning and the mixing of the two streams, a mixture of the bimodal type, but with a maxlmum concentration of coal of 50~ by welght. To increase the concentratlon, it is necessary to pass the mixture through a filter, in order to separate excess water so as to ad~ust the concentration of the coal to the desired value (generally not lower than 70% by weight).
The filterlng operatlon is a difficult and expensive process, and does not always give the desired result.
The wet systems ~ust described suffer above all ~rom the drawback of the filterlng, so the problem to be faced and to be solved is consequently that of forming a bimodal mixture without it being necessary to resort to such filtration.
It has been surprisingly found that it is possible to form a suspension of a bimodal mixture of coal particles at the desirea concentration, the filterlng operatlon thus belng avoided.
According to the present lnvention, there is provided a process for preparlng a suspension of a solld, which comprlses submlttlng the solid to be suspended, after a preliminary crushing down to a maximum size of 6 mm, to two successive wet mlllings, wherein the first milling is a micronization of part of the crushed solid carried out in the presence of addltlve and with a solid:llquid weight ratlo of from 35:65 to 60:40, and wherein the second milllng ls applied to a charge comprlsing ~a) the aqueous .
, - 124~966 suspension of solia partlcles obtalned by the flrst milling and (b) part of the crushed solid, the weight ratio of (a):(b) being from 46:54 to 75:25.
Thus, according to the invention, the solid to be suspended in the liquid, after a preliminary grinding (crushing~ down to a maximum size of the granulated solid of 6 mm, is submltted to two successive wet millings. The flrst milling is a micronization of the ground solid carried out ln the presence of additive, with a solid:liquid weight ratio of from 35:65 to 60:40, preferably 51:49, until there is obtalned an aqueous suspension of solid particles preferably having a maximum size of 20 microns. The second milling is applied to a charge formed by the aqueous suspension of partlcles of solid from the first milling and by granulated solid, the weight ratio between the two components being from 46:54 to 75:25, preferably 51:49 , (aqueous suspension of micronized coal/crushed solid).
The second milling is preferably continued until the maximum size of the granulated solid is 300 microns. In the particular case of coal, the first milling is preferably continued until an average dimension of the particles of from 2 to 8 microns, more preferably of from 3 to 4 microns, is obtained, whilst the second milling is preferably continuea until an average dimenslon is obtained of from 60 to 130 microns (of the coarse solid).
The additive to be used in the first milling is preferably selected from the non-surfactant anionic polyelectrolytes disclosed in the above mentloned French patent, and from the mixtures of sulphonated and salified mixtures containing at least 20~ by weight of aromatic fractions having lnitial boiling points of from 80 to 400C and having at 400C a solid residue at room temperature of from 0 to 80% by welght of lnitial aromatic fractions.
`j ' ~!
. .
124~966 ; 4 Among the addltives of the flrst type we may ; mention as examples DAXAD 15 and D~XAD 19 manufactured I by W.R. Grace, and among those of the second type the ! sulphonated and soda-salified product of the aromatic fraction obtained by pyrolysis at 1100C in the absence of air from a coal from coke.
; The additive is preferably used in an amount of from 0.3 to 3% by weight relative to the solid.
In a preferred embodiment for practically operating the process according to the present invention and for saving energy, the granulated coal is sieved~ so as to subdivide it into two fractions, one I coarse and the other one fine. The fine fraction is micronized in the first milling to the above dimensions and in the speclfied ratio relative to the waterr formlng a suspension which is fed to the second mill as diluent medium, the balance of the charge to the second mill being the coarse fraction.
It is interesting 1O observe that by operating by means of the process according to the present invention, a suspension is obtained wherein the average size of the micronized solid from the first milling is substantially unchanged, notwithstanding the subsequent second milling.
An Example will now be given for the purpose of better illustrating the invention, it being understood that the invention is not to be construed as being limited to this Example or by this Example.
Example There was used an American coal having the following characteristics (analysls based on solid matter):
* (Trade mark) , r ~Z40966 volatile substances = 34 - 35~ by weight ash = 7 - 8~ by weight sulphur = 0.7 ~ by weight net heat value = 7,300 kcal/kg.
s An amount of 70 kg of this coal was crushed to obtain a product having a maximum size of 6 mm.
The product was fed to a classifier box, which sieved the coal into two fractions, namely a fine fraction of 21 kg having a maximum size of 70 microns, and a coarse fraction of 49 kg having a maximum size of 6mm.
The fine fraction was fed to a micronizer mill together with 3~kg of water to which DAXAD* 15 (0.5 kg) had already been added.
The resulting granulometric composition had an average size of 4 microns. The coarse fraction (49 kg) was fed to a finishing rod mill together with the product from the micronizer mill.
A bimodal suspension was obtained containing 70% by weight of coal. The suspension was perfectly stable over a time of more than 1 month, and was free flowing, with a viscosity of 500 cP.
* (Trade mark) -,~
The present invention relates to a process for the preparation of a suspension of a solid at a high concentration. More particularly, the present invention relates to a process for the preparation of a suspension of coal in water at a high concentration, and to such a suspension we will mainly refer in the following disclosure.
For the preparation of a suspension of a solid, in ; 10 particular of coal, it is generally necessary to reduce the solid to such dimensions as to make it possible to maintain it stably suspended in the liquid; thls is done by milling.
According to the presently known axt, the milling can he effected either in a single stage or in a plurality of stages, depending whether a continuous range of particle size or a plurality of ranges of particle size (granulometric size) is desired.
In the specific case of coal, lt has been demonstrated that particularly useful are suspensions containing coal of two different granulometric sizes.
Among these, those disclosed in our Frenchlaid-open Patent Application No. 2,506,323 are particularly useful.
In order to obtain the partlcles of coal with two different granulometric sizes, three milling systems 3, may be used: a dry system, a wet system, or a mixed dry-wet system.
The dry systems are highly polluting and require high investment and operating costs and are being more and more frequently superseded by wet systems.
We will therefore mainly deal with the wet milling systems in connection with the preparation of a coal suspension formed by a mixture of coal particles ~i belonging to two different dimensional ranges ~bimodal mixture).
The wet milling system (coal plus water) for the ' .
~, r~
' suspenslons mentloned are aharacteri~ed by a primary mllling of a mixture of about 50% by weight of coal pre-grouna to a maximum slze of 6 mm, and about 50~ by weight of water, whereby a ground fractlon of coarse type ls obtalned; a portlon of this mlxture ls sent to a micronlzer ln order to form a fine fraction (mlcronized coal) and so as to obtain, after the comblning and the mixing of the two streams, a mixture of the bimodal type, but with a maxlmum concentration of coal of 50~ by welght. To increase the concentratlon, it is necessary to pass the mixture through a filter, in order to separate excess water so as to ad~ust the concentration of the coal to the desired value (generally not lower than 70% by weight).
The filterlng operatlon is a difficult and expensive process, and does not always give the desired result.
The wet systems ~ust described suffer above all ~rom the drawback of the filterlng, so the problem to be faced and to be solved is consequently that of forming a bimodal mixture without it being necessary to resort to such filtration.
It has been surprisingly found that it is possible to form a suspension of a bimodal mixture of coal particles at the desirea concentration, the filterlng operatlon thus belng avoided.
According to the present lnvention, there is provided a process for preparlng a suspension of a solld, which comprlses submlttlng the solid to be suspended, after a preliminary crushing down to a maximum size of 6 mm, to two successive wet mlllings, wherein the first milling is a micronization of part of the crushed solid carried out in the presence of addltlve and with a solid:llquid weight ratlo of from 35:65 to 60:40, and wherein the second milllng ls applied to a charge comprlsing ~a) the aqueous .
, - 124~966 suspension of solia partlcles obtalned by the flrst milling and (b) part of the crushed solid, the weight ratio of (a):(b) being from 46:54 to 75:25.
Thus, according to the invention, the solid to be suspended in the liquid, after a preliminary grinding (crushing~ down to a maximum size of the granulated solid of 6 mm, is submltted to two successive wet millings. The flrst milling is a micronization of the ground solid carried out ln the presence of additive, with a solid:liquid weight ratio of from 35:65 to 60:40, preferably 51:49, until there is obtalned an aqueous suspension of solid particles preferably having a maximum size of 20 microns. The second milling is applied to a charge formed by the aqueous suspension of partlcles of solid from the first milling and by granulated solid, the weight ratio between the two components being from 46:54 to 75:25, preferably 51:49 , (aqueous suspension of micronized coal/crushed solid).
The second milling is preferably continued until the maximum size of the granulated solid is 300 microns. In the particular case of coal, the first milling is preferably continued until an average dimension of the particles of from 2 to 8 microns, more preferably of from 3 to 4 microns, is obtained, whilst the second milling is preferably continuea until an average dimenslon is obtained of from 60 to 130 microns (of the coarse solid).
The additive to be used in the first milling is preferably selected from the non-surfactant anionic polyelectrolytes disclosed in the above mentloned French patent, and from the mixtures of sulphonated and salified mixtures containing at least 20~ by weight of aromatic fractions having lnitial boiling points of from 80 to 400C and having at 400C a solid residue at room temperature of from 0 to 80% by welght of lnitial aromatic fractions.
`j ' ~!
. .
124~966 ; 4 Among the addltives of the flrst type we may ; mention as examples DAXAD 15 and D~XAD 19 manufactured I by W.R. Grace, and among those of the second type the ! sulphonated and soda-salified product of the aromatic fraction obtained by pyrolysis at 1100C in the absence of air from a coal from coke.
; The additive is preferably used in an amount of from 0.3 to 3% by weight relative to the solid.
In a preferred embodiment for practically operating the process according to the present invention and for saving energy, the granulated coal is sieved~ so as to subdivide it into two fractions, one I coarse and the other one fine. The fine fraction is micronized in the first milling to the above dimensions and in the speclfied ratio relative to the waterr formlng a suspension which is fed to the second mill as diluent medium, the balance of the charge to the second mill being the coarse fraction.
It is interesting 1O observe that by operating by means of the process according to the present invention, a suspension is obtained wherein the average size of the micronized solid from the first milling is substantially unchanged, notwithstanding the subsequent second milling.
An Example will now be given for the purpose of better illustrating the invention, it being understood that the invention is not to be construed as being limited to this Example or by this Example.
Example There was used an American coal having the following characteristics (analysls based on solid matter):
* (Trade mark) , r ~Z40966 volatile substances = 34 - 35~ by weight ash = 7 - 8~ by weight sulphur = 0.7 ~ by weight net heat value = 7,300 kcal/kg.
s An amount of 70 kg of this coal was crushed to obtain a product having a maximum size of 6 mm.
The product was fed to a classifier box, which sieved the coal into two fractions, namely a fine fraction of 21 kg having a maximum size of 70 microns, and a coarse fraction of 49 kg having a maximum size of 6mm.
The fine fraction was fed to a micronizer mill together with 3~kg of water to which DAXAD* 15 (0.5 kg) had already been added.
The resulting granulometric composition had an average size of 4 microns. The coarse fraction (49 kg) was fed to a finishing rod mill together with the product from the micronizer mill.
A bimodal suspension was obtained containing 70% by weight of coal. The suspension was perfectly stable over a time of more than 1 month, and was free flowing, with a viscosity of 500 cP.
* (Trade mark) -,~
Claims (10)
1. A process for preparing a suspension of a solid, which comprises submitting the solid to be sus-pended, after a preliminary crushing down to a maximum size of 6 mm, to two successive wet millings, wherein the first milling is a micronization of part of the crushed solid carried out in the presence of additive and with a solid:liquid weight ratio of from 35:65 to 60:40, and wherein the second milling is applied to a charge comprising (a) the aqueous suspension of solid particles obtained by the first milling and (b) part of the crushed solid, the weight ratio of (a):(b) being from 46:54 to 75:25.
2. A process according to claim 1, wherein the second milling is continued until a maximum size of the solid of 300 microns is obtained.
3. A process according to claim 1 or 2, wherein the first milling is continued until a maximum size of 20 microns is obtained.
4. A process according to claim 1, wherein the average size of the particles obtained from the first milling is from 2 to 8 microns.
5. A process according to claim 4, wherein the average size of the particles obtained from the first milling is from 3 to 4 microns.
6. A process according to claim 1, 4 or 5, wherein the average size of the particles obtained from the second milling is from 60 to 130 microns.
7. A process according to claim l, 2 or 3, wherein the first milling is carried out on the fine fraction obtained by sieving the crushed solid, whilst the balance of the charge to the second milling is the coarse fraction obtained by said sieving.
8. A process according to claim 1, 2 or 3, wherein the solid:liquid weight ratio in the first milling is about 51:49.
9. A process according to claim 1, 2 or 3, wherein the weight ratio of (a):(b) in the second milling is about 51:49.
10. A process according to claim 1, 2 or 3, being a process for preparing a suspension of coal in water.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| IT19679A/84 | 1984-02-17 | ||
| IT19679/84A IT1175943B (en) | 1984-02-17 | 1984-02-17 | PROCEDURE FOR THE PREPARATION OF A SUSPENSION OF HIGH CONCENTRATION SOLIDS |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1240966A true CA1240966A (en) | 1988-08-23 |
Family
ID=11160328
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000474439A Expired CA1240966A (en) | 1984-02-17 | 1985-02-15 | Process for the preparation of a suspension of solids at high concentration |
Country Status (10)
| Country | Link |
|---|---|
| AU (1) | AU567791B2 (en) |
| CA (1) | CA1240966A (en) |
| DE (1) | DE3505278A1 (en) |
| GB (1) | GB2154471B (en) |
| IN (1) | IN164129B (en) |
| IT (1) | IT1175943B (en) |
| PL (1) | PL142256B1 (en) |
| SE (1) | SE460828B (en) |
| SU (1) | SU1530099A3 (en) |
| ZA (1) | ZA851054B (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS61123699A (en) * | 1984-11-20 | 1986-06-11 | Electric Power Dev Co Ltd | Production of deashed slurry with high concentration |
| IT1220242B (en) * | 1988-01-25 | 1990-06-06 | Angela Modugno | PROCESS PERFECTED FOR THE PRODUCTION OF MIXTURES, SOLIDS IN LIQUIDS WITH HIGH CONCENTRATION OF SOLIDS |
| RU2743929C1 (en) * | 2020-08-19 | 2021-03-01 | Игорь Нисонович Швецов | Method of producing coal-water fuel |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| 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 |
-
1984
- 1984-02-17 IT IT19679/84A patent/IT1175943B/en active
-
1985
- 1985-02-12 ZA ZA851054A patent/ZA851054B/en unknown
- 1985-02-12 AU AU38650/85A patent/AU567791B2/en not_active Ceased
- 1985-02-12 SE SE8500640A patent/SE460828B/en not_active IP Right Cessation
- 1985-02-13 GB GB08503655A patent/GB2154471B/en not_active Expired
- 1985-02-15 DE DE19853505278 patent/DE3505278A1/en active Granted
- 1985-02-15 PL PL1985251965A patent/PL142256B1/en unknown
- 1985-02-15 IN IN130/MAS/85A patent/IN164129B/en unknown
- 1985-02-15 SU SU853863654A patent/SU1530099A3/en active
- 1985-02-15 CA CA000474439A patent/CA1240966A/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| AU567791B2 (en) | 1987-12-03 |
| IT8419679A0 (en) | 1984-02-17 |
| AU3865085A (en) | 1985-08-22 |
| DE3505278A1 (en) | 1985-08-22 |
| IT1175943B (en) | 1987-08-12 |
| IN164129B (en) | 1989-01-14 |
| PL142256B1 (en) | 1987-10-31 |
| SE460828B (en) | 1989-11-27 |
| ZA851054B (en) | 1985-09-25 |
| GB2154471B (en) | 1987-07-01 |
| DE3505278C2 (en) | 1987-06-25 |
| SE8500640D0 (en) | 1985-02-12 |
| GB8503655D0 (en) | 1985-03-13 |
| SU1530099A3 (en) | 1989-12-15 |
| PL251965A1 (en) | 1985-11-19 |
| SE8500640L (en) | 1985-08-18 |
| GB2154471A (en) | 1985-09-11 |
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