CA1101137A - Coal beneficiation - Google Patents
Coal beneficiationInfo
- Publication number
- CA1101137A CA1101137A CA306,219A CA306219A CA1101137A CA 1101137 A CA1101137 A CA 1101137A CA 306219 A CA306219 A CA 306219A CA 1101137 A CA1101137 A CA 1101137A
- Authority
- CA
- Canada
- Prior art keywords
- coal
- slurry
- particles
- suspension
- tailings
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B03—SEPARATION OF SOLID MATERIALS USING LIQUIDS OR USING PNEUMATIC TABLES OR JIGS; MAGNETIC OR ELECTROSTATIC SEPARATION OF SOLID MATERIALS FROM SOLID MATERIALS OR FLUIDS; SEPARATION BY HIGH-VOLTAGE ELECTRIC FIELDS
- B03B—SEPARATING SOLID MATERIALS USING LIQUIDS OR USING PNEUMATIC TABLES OR JIGS
- B03B9/00—General arrangement of separating plant, e.g. flow sheets
- B03B9/04—General arrangement of separating plant, e.g. flow sheets specially adapted for furnace residues, smeltings, or foundry slags
Landscapes
- Separation Of Solids By Using Liquids Or Pneumatic Power (AREA)
- Compounds Of Iron (AREA)
- Solid Fuels And Fuel-Associated Substances (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
Coal fines are mixed with a magnetite suspension to a gravity hydrocyclone. Each of the underflow and the overflow are subjected to a reverse flotation to recover magnetite. The tailings of the reverse flotation are then cleaned by floating the coal fines.
Coal fines are mixed with a magnetite suspension to a gravity hydrocyclone. Each of the underflow and the overflow are subjected to a reverse flotation to recover magnetite. The tailings of the reverse flotation are then cleaned by floating the coal fines.
Description
Field of th _ nventjon, THIS invention relates to coal beneficiation processes in which coal fines are separated into a fraction which is low in ash and a fraction which is high in ash.
Background of the Invention.
.
Coal fines with a high ash content can be upgraded by means of a known dense medium separation method. In this method the coal fines are added to a suspension made up of dense medium particles, e.g. magnetite particles, in water, the density of the slurry being adjusted to be about 1,4. The m;xture of coal and the suspension is then fed to a cyclone separator.
.The light or overflow fraction from the cyclone contains a high proportion of coal fines lo~ in ash together with some dense i` medium particles, while the dense or underflow fraction conta;ns , a high proportion of dense medium particles, high ash coal and ash constitutents.
:
Having obtained these two fractions one then has to recover the ~ ~ dense medium particles so that they may be recirculated for ; use in the process. With coarse coal th;s is readily achieved ~y screening and washing. With ~jne coal particles other :
'~ :
Background of the Invention.
.
Coal fines with a high ash content can be upgraded by means of a known dense medium separation method. In this method the coal fines are added to a suspension made up of dense medium particles, e.g. magnetite particles, in water, the density of the slurry being adjusted to be about 1,4. The m;xture of coal and the suspension is then fed to a cyclone separator.
.The light or overflow fraction from the cyclone contains a high proportion of coal fines lo~ in ash together with some dense i` medium particles, while the dense or underflow fraction conta;ns , a high proportion of dense medium particles, high ash coal and ash constitutents.
:
Having obtained these two fractions one then has to recover the ~ ~ dense medium particles so that they may be recirculated for ; use in the process. With coarse coal th;s is readily achieved ~y screening and washing. With ~jne coal particles other :
'~ :
- 2 -~ , - : . - . . - -. , ~ , ~ . - .: . ~ . -., , . .
\
37 .
` measures have to ~e resQrted to.
.
Since coal particles are easily rendered hydrophobic, an obvious other measure is to float the coal particles from the slurries, leaving heavy medium particles behind - see British patent No. 827 443. However, with fine high density particles, such as magnetite fines, these float with the coal.
-Summary of the Invention.
.
According to the invent;on a method of benefic;at;ng coal fines of a particle s;ze less than 0,5 mm comprising the steps of lo introducing a ~ixture of coal and a suspension of water and particles of a dense medium to a gravity separation in which high ash coal is obtained as an underflow slurry and low ash coal is obtained as an ov~rflow slurry~ and the dense medium . ~
~ particles from both the underflow and the overflow slurries ~ ~ .
~:` 15 are recovered to be reused to make up the suspension; ;s characterised by the step of submitting either or both of the underflow slurry and the overflow slurry to a first froth flDtation process in which a wetting agent adapted to render ~ ` the surfaces of the coal particles hydrophil1ic is added to - ;~ 20 the slurry and the slurry is subjected to froth flotation so that the dense medium particles report in the float fraction of the first flotation process and are then used to make up , ~ .
, ' ., ':
,: ' ' - ', . ~ , .
-, , ~ ~ . '' :
, . ~
~L1~3L1 3 7 the suspension.
The wetting agent may be an e~ulsifjer such as a sulphonic acid type anionic emulsifier. A salt of R SO2 NH2 CH2 COOH, wherein R is alkyl, has proved to be highly effective.
Virtually only dense medium particles report in the float of the first froth flotation process. However, some of the dense medium partic1es remain in the tailings and need to be recovered. This recovery may be done by a second froth~flotation process after rendering the coal particle hydrophobic as by treating the tailings with a petroleum hydrocarbon oil.
- Alternatively the tailings may be treated in a magnetic separation process to recover dense medium particles. Of course, in the latter case the dense medium particles must be magnetic or magnetizable.
; ' - ~ ~ .
;~ lS Description of the Drawing.
,: .
It shows a flow sheet of a process according to the invention for treat;ng coal fines.
~ .
Description of a~Preferred Embodiment~
In the illustrated flow sheet coal fines of particle size minus *!
~, . . , . ' - .
' :' ' : .
1 1C~ 1 1 3 7 0,5 mm is first mixed at lO wlth a suspension of magnetite in water made up to give the correct separation density, $ay, 1,4. The mixture is then ~ed to a cyclone separator ll.
The overflow and the underfiow from the separator ll are treated in an identical manner in two separate circuits.
Dealing first with the overflow it is fed to a conditioner 12 where a cationic emu1sifier is added as well as a suitable frothing agent such as methyl isobutyl carbinol. From the cond;tioner l2 the overflow slurry passes to a rougher flotation section 13. The float from this section, which is ` substantially pure magnetite is returned to the suspension ~, ~ preparation section 14. The tailings go to a further conditioner .' . ~ , .
, In the conditioner l5 a hydrocarbon oil is added to render the ~ coal particles hydrophobic and the conditioned product passes to a cleaner flotation section 16. Here a clean coal product is the float and the tailings is substantially pure magnetite which is also returned to l4.
~ Likewise the underflow from the cyclone ll passes through a ``; 20 conditioner 17, a rougher flotation section 18~ a cond;tioner ~ ~ l9 and a c1eaner flotation section 20; The float from the ~ . .
' . :,. ~, ~ ' :
~ ' - ' - ' : .
.
~1~1137 section 18 and the tailing from the section 20 go to the secti~n 14. The float from the section 20 represents the high ash coal fraction, which is generally discarded. The product of the process is the float from the section 16 from which fine coal is obtained in a conventional manner.
Example:
.
In an example of the invention coal fines less than 0,5 mm in size were treated in a heavy medium suspension made up of magnetite of which 95 % was less that 44 microns. The suspension was prepared in the conventional manner to achieve an apparent density of about 1,4.
The mixture of coal fines and suspension was fed to a standard hydrocyclone separator to produce an overflow slurry containing 63,5 % magnetite and 36,5 % 1GW ash coal fines and an underflow slurry containing 84,6 % magnetite and 15,4 % high ash coal fines all by weight.
;:
The two slurries were conditioned separate1y by adding to them 0,5 kg/t of an ionic emulsifier, Emu~sogen STH obtained from Hoechst as well as methy~ isobutyl carbin~l as a frothing agent.
.
.
~ - 6 -,: .~- ~ , - .
- -:
- - ' . . . ' .
.
~1~1137 The conditioned slurries were separately treated in rougher froth flotation cells, In the case of the ~Yerflow slurry 89,9 % of the magnetite present reported in the float and the case of the underf~ow slurry 84,9 % of the magnetite present reported in the float. These f70ats were returned to the suspension make up section.
The tailings from the rougher flotation sections were then separately conditioned with 0,8 kg/ton of dry feed of kerosene to render the coal fractions hydrophobic. They were then separately subjected to froth flotation in cleaner flotation cells. In the case of the,overflow slurry 7,1 % and in the case of the underflo~ slurry 17,5 % of the magnetite calculated on the original feed, reported in the tailings.
. ~ .
, In the case of the underflow 99,4 % of the magnetite was reco,vered and in the case of the overflow 96,9 % was recovered.
-~ ' The loss of magnetite to the coal fractions is thus negligible.
~ ~.
`, The key to the high magnetite recovery is to float it from the t!~lo coal fractions. Thereafter the remainder can be recovered in the tailings after floating off the coal or by means of a magnetic separation. The low concentration of magnetite in ~ ~ ~ the product being treated makes magnetic separation highly '~
;
,~
.~
:' :
.. ~
' .: ' ,, . - ~- .
.
11~1137 .
economjcal 4ver the tre~at~ent of the whole Qf the underflo~
or the overflow, as the case may be, in a magnetic separation process. It is well kno~m that magnetic separation from a suspension in which the magnetic fractions is highly diluted is more ef~icient and economical than the recovery from a suspension in which it is highly concentrated.
(' In an experiment the tailings from a rougher flotation cell was subjected to a double stage magnetic separation. The result was that between the magnetic separator and the cleaner flotation 100 / of the magnetite was recovered.
' .~; .
.~ .
.' ~ ,:
' , .
, ~
;~ ' , .
.
, , .
~, .
.~ .
, : .
`: : :
.. . ..
,. ~
.
- - .
- . . . : - . . ~
.
.
\
37 .
` measures have to ~e resQrted to.
.
Since coal particles are easily rendered hydrophobic, an obvious other measure is to float the coal particles from the slurries, leaving heavy medium particles behind - see British patent No. 827 443. However, with fine high density particles, such as magnetite fines, these float with the coal.
-Summary of the Invention.
.
According to the invent;on a method of benefic;at;ng coal fines of a particle s;ze less than 0,5 mm comprising the steps of lo introducing a ~ixture of coal and a suspension of water and particles of a dense medium to a gravity separation in which high ash coal is obtained as an underflow slurry and low ash coal is obtained as an ov~rflow slurry~ and the dense medium . ~
~ particles from both the underflow and the overflow slurries ~ ~ .
~:` 15 are recovered to be reused to make up the suspension; ;s characterised by the step of submitting either or both of the underflow slurry and the overflow slurry to a first froth flDtation process in which a wetting agent adapted to render ~ ` the surfaces of the coal particles hydrophil1ic is added to - ;~ 20 the slurry and the slurry is subjected to froth flotation so that the dense medium particles report in the float fraction of the first flotation process and are then used to make up , ~ .
, ' ., ':
,: ' ' - ', . ~ , .
-, , ~ ~ . '' :
, . ~
~L1~3L1 3 7 the suspension.
The wetting agent may be an e~ulsifjer such as a sulphonic acid type anionic emulsifier. A salt of R SO2 NH2 CH2 COOH, wherein R is alkyl, has proved to be highly effective.
Virtually only dense medium particles report in the float of the first froth flotation process. However, some of the dense medium partic1es remain in the tailings and need to be recovered. This recovery may be done by a second froth~flotation process after rendering the coal particle hydrophobic as by treating the tailings with a petroleum hydrocarbon oil.
- Alternatively the tailings may be treated in a magnetic separation process to recover dense medium particles. Of course, in the latter case the dense medium particles must be magnetic or magnetizable.
; ' - ~ ~ .
;~ lS Description of the Drawing.
,: .
It shows a flow sheet of a process according to the invention for treat;ng coal fines.
~ .
Description of a~Preferred Embodiment~
In the illustrated flow sheet coal fines of particle size minus *!
~, . . , . ' - .
' :' ' : .
1 1C~ 1 1 3 7 0,5 mm is first mixed at lO wlth a suspension of magnetite in water made up to give the correct separation density, $ay, 1,4. The mixture is then ~ed to a cyclone separator ll.
The overflow and the underfiow from the separator ll are treated in an identical manner in two separate circuits.
Dealing first with the overflow it is fed to a conditioner 12 where a cationic emu1sifier is added as well as a suitable frothing agent such as methyl isobutyl carbinol. From the cond;tioner l2 the overflow slurry passes to a rougher flotation section 13. The float from this section, which is ` substantially pure magnetite is returned to the suspension ~, ~ preparation section 14. The tailings go to a further conditioner .' . ~ , .
, In the conditioner l5 a hydrocarbon oil is added to render the ~ coal particles hydrophobic and the conditioned product passes to a cleaner flotation section 16. Here a clean coal product is the float and the tailings is substantially pure magnetite which is also returned to l4.
~ Likewise the underflow from the cyclone ll passes through a ``; 20 conditioner 17, a rougher flotation section 18~ a cond;tioner ~ ~ l9 and a c1eaner flotation section 20; The float from the ~ . .
' . :,. ~, ~ ' :
~ ' - ' - ' : .
.
~1~1137 section 18 and the tailing from the section 20 go to the secti~n 14. The float from the section 20 represents the high ash coal fraction, which is generally discarded. The product of the process is the float from the section 16 from which fine coal is obtained in a conventional manner.
Example:
.
In an example of the invention coal fines less than 0,5 mm in size were treated in a heavy medium suspension made up of magnetite of which 95 % was less that 44 microns. The suspension was prepared in the conventional manner to achieve an apparent density of about 1,4.
The mixture of coal fines and suspension was fed to a standard hydrocyclone separator to produce an overflow slurry containing 63,5 % magnetite and 36,5 % 1GW ash coal fines and an underflow slurry containing 84,6 % magnetite and 15,4 % high ash coal fines all by weight.
;:
The two slurries were conditioned separate1y by adding to them 0,5 kg/t of an ionic emulsifier, Emu~sogen STH obtained from Hoechst as well as methy~ isobutyl carbin~l as a frothing agent.
.
.
~ - 6 -,: .~- ~ , - .
- -:
- - ' . . . ' .
.
~1~1137 The conditioned slurries were separately treated in rougher froth flotation cells, In the case of the ~Yerflow slurry 89,9 % of the magnetite present reported in the float and the case of the underf~ow slurry 84,9 % of the magnetite present reported in the float. These f70ats were returned to the suspension make up section.
The tailings from the rougher flotation sections were then separately conditioned with 0,8 kg/ton of dry feed of kerosene to render the coal fractions hydrophobic. They were then separately subjected to froth flotation in cleaner flotation cells. In the case of the,overflow slurry 7,1 % and in the case of the underflo~ slurry 17,5 % of the magnetite calculated on the original feed, reported in the tailings.
. ~ .
, In the case of the underflow 99,4 % of the magnetite was reco,vered and in the case of the overflow 96,9 % was recovered.
-~ ' The loss of magnetite to the coal fractions is thus negligible.
~ ~.
`, The key to the high magnetite recovery is to float it from the t!~lo coal fractions. Thereafter the remainder can be recovered in the tailings after floating off the coal or by means of a magnetic separation. The low concentration of magnetite in ~ ~ ~ the product being treated makes magnetic separation highly '~
;
,~
.~
:' :
.. ~
' .: ' ,, . - ~- .
.
11~1137 .
economjcal 4ver the tre~at~ent of the whole Qf the underflo~
or the overflow, as the case may be, in a magnetic separation process. It is well kno~m that magnetic separation from a suspension in which the magnetic fractions is highly diluted is more ef~icient and economical than the recovery from a suspension in which it is highly concentrated.
(' In an experiment the tailings from a rougher flotation cell was subjected to a double stage magnetic separation. The result was that between the magnetic separator and the cleaner flotation 100 / of the magnetite was recovered.
' .~; .
.~ .
.' ~ ,:
' , .
, ~
;~ ' , .
.
, , .
~, .
.~ .
, : .
`: : :
.. . ..
,. ~
.
- - .
- . . . : - . . ~
.
.
Claims
THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1.
A method of beneficiating coal fines of a particle size less than 0,5 mm comprising the steps of introducing a mixture of coal and a suspension of water and particles of a dense medium to a gravity separation in which high ash coal is obtained as an underflow slurry and low ash coal is obtained as an overflow slurry and the dense medium particles from both the underflow and the overflow slurries are recovered to be reused to make up the suspension characterized by the step of submitting either or both of the underflow slurry and the overflow slurry to a first froth flotation process in which a wetting agent adapted to render the surfaces of the coal particles hydrophillic is added to the slurry and the slurry is subjected to froth flotation so that the dense medium particles report in the float fraction of the first flotation process and are then used to make up the suspension.
2.
The method claimed in claim 1 in which the wetting agent is an anionic emulsifier.
3.
The method claimed in claim 2 in which the emulsifier is a sulphonic acid type emulsifier.
4.
The method claimed in claim 3 in which the emulsifier is a salt of R SO2 NH2 CH2 COOH wherein R is alkyl.
5.
The method claimed in claim 1 in which the tailings from the first froth flotation process are treated with a substance to render the coal particles hydrophobic and these tailings are subjected to a second froth flotation, the coal fines reporting in the float and the tailings being used to make up the suspension.
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1.
A method of beneficiating coal fines of a particle size less than 0,5 mm comprising the steps of introducing a mixture of coal and a suspension of water and particles of a dense medium to a gravity separation in which high ash coal is obtained as an underflow slurry and low ash coal is obtained as an overflow slurry and the dense medium particles from both the underflow and the overflow slurries are recovered to be reused to make up the suspension characterized by the step of submitting either or both of the underflow slurry and the overflow slurry to a first froth flotation process in which a wetting agent adapted to render the surfaces of the coal particles hydrophillic is added to the slurry and the slurry is subjected to froth flotation so that the dense medium particles report in the float fraction of the first flotation process and are then used to make up the suspension.
2.
The method claimed in claim 1 in which the wetting agent is an anionic emulsifier.
3.
The method claimed in claim 2 in which the emulsifier is a sulphonic acid type emulsifier.
4.
The method claimed in claim 3 in which the emulsifier is a salt of R SO2 NH2 CH2 COOH wherein R is alkyl.
5.
The method claimed in claim 1 in which the tailings from the first froth flotation process are treated with a substance to render the coal particles hydrophobic and these tailings are subjected to a second froth flotation, the coal fines reporting in the float and the tailings being used to make up the suspension.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| ZA00773838A ZA773838B (en) | 1977-06-27 | 1977-06-27 | Coal benefication |
| ZA77/3838 | 1977-06-27 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1101137A true CA1101137A (en) | 1981-05-12 |
Family
ID=25571732
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA306,219A Expired CA1101137A (en) | 1977-06-27 | 1978-06-26 | Coal beneficiation |
Country Status (12)
| Country | Link |
|---|---|
| AU (1) | AU3742078A (en) |
| BE (1) | BE868432A (en) |
| CA (1) | CA1101137A (en) |
| DE (1) | DE2827929A1 (en) |
| FR (1) | FR2395782A1 (en) |
| GB (1) | GB2000052A (en) |
| IN (1) | IN148359B (en) |
| LU (1) | LU79870A1 (en) |
| NL (1) | NL7806711A (en) |
| PL (1) | PL207923A1 (en) |
| ZA (1) | ZA773838B (en) |
| ZM (1) | ZM5478A1 (en) |
Families Citing this family (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4484928A (en) * | 1982-05-27 | 1984-11-27 | Otisca Industries, Inc. | Methods for processing coal |
| EP0365537A4 (en) * | 1987-06-10 | 1990-06-28 | Conoco Specialty Prod | Liquid separator. |
| US5298167A (en) * | 1992-12-10 | 1994-03-29 | Arnold Kenneth E | Method for separating immiscible liquid |
| CN102500466B (en) * | 2011-12-28 | 2013-04-17 | 高华 | Technique for recycling cleaned coal from low-value gangue or tail coal of coal washery |
| CN103071583B (en) * | 2013-01-28 | 2016-01-13 | 中国煤炭进出口公司 | The control method of density of heavy medium and system in a kind of dense-medium separation |
| PT2999772T (en) | 2013-05-21 | 2018-02-15 | Univ Nelson Mandela Metropolitan | Upgrading coal fines using microalgae |
| CN104258978A (en) * | 2014-08-27 | 2015-01-07 | 杨晋新 | Method for improving recovery rate of washed coal by decreasing additional ash content |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB827443A (en) * | 1958-03-12 | 1960-02-03 | Stamicarbon | Process of regenerating separating suspensions in coal and ore washeries, and apparatus therefor |
-
1977
- 1977-06-27 ZA ZA00773838A patent/ZA773838B/en unknown
-
1978
- 1978-06-14 ZM ZM54/78A patent/ZM5478A1/en unknown
- 1978-06-15 IN IN446/DEL/78A patent/IN148359B/en unknown
- 1978-06-16 GB GB7827148A patent/GB2000052A/en not_active Withdrawn
- 1978-06-21 NL NL7806711A patent/NL7806711A/en not_active Application Discontinuation
- 1978-06-23 AU AU37420/78A patent/AU3742078A/en active Pending
- 1978-06-26 CA CA306,219A patent/CA1101137A/en not_active Expired
- 1978-06-26 BE BE2057091A patent/BE868432A/en not_active IP Right Cessation
- 1978-06-26 DE DE19782827929 patent/DE2827929A1/en not_active Withdrawn
- 1978-06-26 FR FR7819042A patent/FR2395782A1/en not_active Withdrawn
- 1978-06-26 LU LU79870A patent/LU79870A1/xx unknown
- 1978-06-26 PL PL20792378A patent/PL207923A1/en unknown
Also Published As
| Publication number | Publication date |
|---|---|
| DE2827929A1 (en) | 1979-01-11 |
| NL7806711A (en) | 1978-12-29 |
| ZA773838B (en) | 1978-09-27 |
| LU79870A1 (en) | 1978-12-07 |
| BE868432A (en) | 1978-10-16 |
| FR2395782A1 (en) | 1979-01-26 |
| ZM5478A1 (en) | 1979-06-21 |
| IN148359B (en) | 1981-01-24 |
| GB2000052A (en) | 1979-01-04 |
| PL207923A1 (en) | 1979-04-23 |
| AU3742078A (en) | 1980-01-03 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |