CA1329149C - Process of purifying the exhaust gases from a sintering plant - Google Patents
Process of purifying the exhaust gases from a sintering plantInfo
- Publication number
- CA1329149C CA1329149C CA 607459 CA607459A CA1329149C CA 1329149 C CA1329149 C CA 1329149C CA 607459 CA607459 CA 607459 CA 607459 A CA607459 A CA 607459A CA 1329149 C CA1329149 C CA 1329149C
- Authority
- CA
- Canada
- Prior art keywords
- spray dryer
- electrostatic precipitator
- chlorides
- sintering plant
- solvent
- 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 - Fee Related
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
- B03C—MAGNETIC OR ELECTROSTATIC SEPARATION OF SOLID MATERIALS FROM SOLID MATERIALS OR FLUIDS; SEPARATION BY HIGH-VOLTAGE ELECTRIC FIELDS
- B03C3/00—Separating dispersed particles from gases or vapour, e.g. air, by electrostatic effect
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
- C22B7/00—Working up raw materials other than ores, e.g. scrap, to produce non-ferrous metals and compounds thereof; Methods of a general interest or applied to the winning of more than two metals
- C22B7/02—Working-up flue dust
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P10/00—Technologies related to metal processing
- Y02P10/20—Recycling
Landscapes
- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Geology (AREA)
- Life Sciences & Earth Sciences (AREA)
- General Life Sciences & Earth Sciences (AREA)
- Manufacturing & Machinery (AREA)
- Environmental & Geological Engineering (AREA)
- Materials Engineering (AREA)
- Mechanical Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Treating Waste Gases (AREA)
- Electrostatic Separation (AREA)
- Manufacture And Refinement Of Metals (AREA)
- Waste-Gas Treatment And Other Accessory Devices For Furnaces (AREA)
Abstract
ABSTRACT
Exhaust gases from a sintering plant are passed through an electrostatic precipitator, in which a dust mixture which contains chlorides is separated. By an addition of a solvent, such as water, to at least part of the dust mixture the chlorides are dissolved. The solids are separated from the solution and the solution which is substantially free of solids is contacted in a spray dryer with hot exhaust gas from the sintering plant. Substantially dried chlorides are removed from the spray dryer. The solvent-containing exhaust gas from the spray dryer is supplied to the electrostatic precipitator.
Exhaust gases from a sintering plant are passed through an electrostatic precipitator, in which a dust mixture which contains chlorides is separated. By an addition of a solvent, such as water, to at least part of the dust mixture the chlorides are dissolved. The solids are separated from the solution and the solution which is substantially free of solids is contacted in a spray dryer with hot exhaust gas from the sintering plant. Substantially dried chlorides are removed from the spray dryer. The solvent-containing exhaust gas from the spray dryer is supplied to the electrostatic precipitator.
Description
: 2 '~
~L32~149 DESCRIPTION
Thls invention relates to a process of purifying the exhaust gases from a sintering plant, ~herein the exhaust gases are passed through an electrostatic precipitator to se-parate a dust mixture which contains chlorides and which is recycled in part to the sintering plant.
A report on sintering plants and on the purifi-cation of their exhaust gases by an electrostatic precipitator is contained in the periodical "~last Furnace, Coke ~ven and Raw Materials, Proceedings" 18 ~1959), on pages 233 to Z49~
~ecause the sol.ids contained in the exhaust gas from sintering plants have a heterogeneous composition1 considerable diffi-culties are involved in the purification of said exhaust gases.
Problems arise mainly owing to the fact that salts, particu-larly alkali chlorides, are contained in the exhaust gas and can be separated only with difficulty in the electrostatic pre-cipitator. If the separated solids are recycled to the sin-tering plant, as i5 usual, the content of the difficultly separable solids in the exhaust ga~ will progressively increase so that an expensive electrostatic precipitator will be re-quired.
It i9 an object of the invention tOI remove from the process tu the highest possihle degree the chlorides which have been separated in the electrostatic precipitator whereas the amount of solids ~o be disaosed of should not disturbingly .
. ~ ' . ~, ,.
~2~1~9 increase. In the proces~ mentioned first hereinbe~ore this i9 accomplished in accordance with the invention in that a sal-vent i~ added to at least part o~ the dust mixture and the chlorides are disqolved, solids are separated from the 901u-tion, the solvent i~ directly contacted in a spray dryer with hot exhauqt gas from the sintering plant, substantially dried chlorides are removed from the spray dryer, and the solvent-containing exhaust gas from the 3pray dryer is supplied to the electrostatic precipitator. ~ecause the dried chlorides are usually rich in potassium chloride, they may be used to pro-duce fertilizers; otherwise they are dumped.
It i9 recommendable to use water as a solvent.
A considerable part of that ~ater is contained in the exhaust gas from the spray dryer and enters the electrostatic precipi-tator. As a result, the exhaust gas to be treated in the elec-trostatic precipitator is enriched in a simple and inexpensive manner with water vapor~ which will improve the ~eparation rate of the precipitator.
It has been found that the salts which are se-parated in the electrostatic precipitator become available adjacent to the gas outlet of the electrostatic precipitator and become enriched in the associated bins. Forlthis reason that region of the electrostatic precipitator may oe designed as a wet-process electrostatic precipitator so that the ~.
, .
,, ' 132~1~9 separated salts, partlcularly chlar~des, will ~e dissolved already in the bin by the water which has been sprayed into the electrostatic precipitator.
Details of the process will be explained with reference to the dra~ing.
A sintering plant 1, which is known per se, is supplied ~ith ore through line 2. Solids-containing exhaust gases are withdrawn do~nwardly through suction boxes 3 from said plant and are supplied via a collecting line 5 to an elec-trostatic precipitator 6. The solids which have been separated in the electrostatic precipitator 6 are collected in a plu-rality of bins 7, ~, only two of ~hich are shown in the drawing for the sake of simplicity. The dedusted exhaust gas is de-livered by the fan 10 to the chimney 11.
Salts, particularly alkali chlorides, should not become enriched in the exhaust gas and are separated in the electrostatic precipitator preferably adjacent ot the gas out-let and are collected in the bin a. In order to dissolve saio salts, water is fed to the bin vla line 1Z and the resulting mixture is conducted through the drain 13 to a settling tank 14. Undissolued solids, particularly ~ine ore, will collect as a solios-containing phase in the bottom portion!of the tank 14 and together with the solids fro~ the bin 7 are recycled in line 15 to the sintering plant 1.
The substantial1y solids-free salt solutiQn wnicn is form~d in the settling tank 14 is con~ucted in lino 17 and ~. . . .
.
: , ,. :........ ..
preferably initially to a precipita~ing plant 1~, in which heavy metals are separated. In the plant 1~ the heavy metals are converted to insoluble campounds, e.g., by an addition of precipitants, and are separateo. Separated heavy metals are withdrawn in line 2~ and in most cases are dumped. The salt solution from which th2 heavy metals have substantially been removed is supplied in a line 21 to a spray drier 22 and is sprayed therein.
The spray dryer 22 i5 supplied via line 24 with a partial stream of the hot exhaust gas from the sintering plant. That partial stream of exhaust gaq i9 usually at a temperature in the range from Z00 to 400C. That partial stream of exhaust gas i9 preferably withdrawn from the hottest region of the sintering plant ~, the suction boxes 3a of which are disposed in the last one-third of the sintering plant. In the spray dryer 22, the hot exhaust gases from line 24 take up the moisture of the solution ~hich comes from the line 21 and has been sprayed. As a result, substantially dried salts sub-side to the bottom of the spray dryer and are withdrawn through the line Z5. The exhaust gases which contain water vapor l~ave the spray dryer 22 through the line Z6 and are subjected to a coarse dedusting in a cyclone 27 and are subsPquently con-ducted in line 2~ and admixed to the hot gases in line 5. The solids which are withdrawn from the cyclone 27 in line 29 are preferably also recycled to the sintering olant 1. If the de-dusting cyclone 27 may be omitte~, the exhaust gases are , ': ' ' ' , '., ' . ' ~ 1329~
:
directly supplied to the electrostatic precipitator via the by-pass line 28a and the line 28.
That region of the electrostatic precipitator 6 ~hich i~ adjacent to the gas outlet may be designed as a ~et-process electrastatic precipitator. In that case that region of the precipitator is provided with a ~ater inlet 30 for a supply of water which is sprayed in the associated region oF
the precipitator~ The separated solids w~ll cole~t as a sludge in the associated bin B. A supply of additional water in line 1Z may not be requried. The sludge is processed in the settling tank 14 as has been described.
EXAMPLE
` In a plant which was as shown in the orawing but in which the heavy metal separator 18 and the cyclone 2~ ~ere ~ omitted, a mixture which contains fine iron ore, fluxes and -~ fine coke and has a content of CaO and SiO2 in a ~eight ratio of 1.8 (basicity) i~ supplied in line Z to the sintering plant 1. The slntering plant has a suction area of ZBO mZ and pro-duces an exhaust gas at a total rate of ~oo~ooa sm3fh (sm3 =
standard cubic meter). That ga3 is at a temperature of 134C, and has a water dew point temperature oF 40~C and a dust content o~ 1 g/m3 as it enters the electrostatic precipi~ator 6. ~00 kg ' dust per hour are supplied to the electrostatic precipitator in ;~ the exhaust gas.
; Dust at a rate of 300 kg~h is collected in the , last bin B of the eiectrostatic p~ecipitator and cnntains 62%
.~ .
,. . .
.
- ~. -.. ,~ . . '' ,. ' : . .
.
~.
'~
. r~
2gl4L9 by weight of Roluble ~alts, particularly KCl and NaCl. Water at a rate of 1900 kg/h i9 added to that dust, which i9 then supplied to the settling tank 14. A chlnride-containing 90-lution at a rate of about 2000 kg/h is ~upplied to the spray dryer 22, ~hich is supplied in line Z4 at a rate of about 30,D00 sm3/h wlth an exhaust gas at a temperature af 2709C.
The residual moisture content oF the salt in line Z5 i9 about 3% by weight. The e~hau3t gas in line 28 has a temperature of 140C. ~ecause a ma~or part of the chlorides is separated in the spray dryer 22, the puri~ied exhaust gas in the chimney 11 has a dust content of only 30 mg /sm3 although a major part of the solids which have been separated in the electrostatic precipitator are recycled.
.
!
, , ;
;
, , . .
", .
~L32~149 DESCRIPTION
Thls invention relates to a process of purifying the exhaust gases from a sintering plant, ~herein the exhaust gases are passed through an electrostatic precipitator to se-parate a dust mixture which contains chlorides and which is recycled in part to the sintering plant.
A report on sintering plants and on the purifi-cation of their exhaust gases by an electrostatic precipitator is contained in the periodical "~last Furnace, Coke ~ven and Raw Materials, Proceedings" 18 ~1959), on pages 233 to Z49~
~ecause the sol.ids contained in the exhaust gas from sintering plants have a heterogeneous composition1 considerable diffi-culties are involved in the purification of said exhaust gases.
Problems arise mainly owing to the fact that salts, particu-larly alkali chlorides, are contained in the exhaust gas and can be separated only with difficulty in the electrostatic pre-cipitator. If the separated solids are recycled to the sin-tering plant, as i5 usual, the content of the difficultly separable solids in the exhaust ga~ will progressively increase so that an expensive electrostatic precipitator will be re-quired.
It i9 an object of the invention tOI remove from the process tu the highest possihle degree the chlorides which have been separated in the electrostatic precipitator whereas the amount of solids ~o be disaosed of should not disturbingly .
. ~ ' . ~, ,.
~2~1~9 increase. In the proces~ mentioned first hereinbe~ore this i9 accomplished in accordance with the invention in that a sal-vent i~ added to at least part o~ the dust mixture and the chlorides are disqolved, solids are separated from the 901u-tion, the solvent i~ directly contacted in a spray dryer with hot exhauqt gas from the sintering plant, substantially dried chlorides are removed from the spray dryer, and the solvent-containing exhaust gas from the 3pray dryer is supplied to the electrostatic precipitator. ~ecause the dried chlorides are usually rich in potassium chloride, they may be used to pro-duce fertilizers; otherwise they are dumped.
It i9 recommendable to use water as a solvent.
A considerable part of that ~ater is contained in the exhaust gas from the spray dryer and enters the electrostatic precipi-tator. As a result, the exhaust gas to be treated in the elec-trostatic precipitator is enriched in a simple and inexpensive manner with water vapor~ which will improve the ~eparation rate of the precipitator.
It has been found that the salts which are se-parated in the electrostatic precipitator become available adjacent to the gas outlet of the electrostatic precipitator and become enriched in the associated bins. Forlthis reason that region of the electrostatic precipitator may oe designed as a wet-process electrostatic precipitator so that the ~.
, .
,, ' 132~1~9 separated salts, partlcularly chlar~des, will ~e dissolved already in the bin by the water which has been sprayed into the electrostatic precipitator.
Details of the process will be explained with reference to the dra~ing.
A sintering plant 1, which is known per se, is supplied ~ith ore through line 2. Solids-containing exhaust gases are withdrawn do~nwardly through suction boxes 3 from said plant and are supplied via a collecting line 5 to an elec-trostatic precipitator 6. The solids which have been separated in the electrostatic precipitator 6 are collected in a plu-rality of bins 7, ~, only two of ~hich are shown in the drawing for the sake of simplicity. The dedusted exhaust gas is de-livered by the fan 10 to the chimney 11.
Salts, particularly alkali chlorides, should not become enriched in the exhaust gas and are separated in the electrostatic precipitator preferably adjacent ot the gas out-let and are collected in the bin a. In order to dissolve saio salts, water is fed to the bin vla line 1Z and the resulting mixture is conducted through the drain 13 to a settling tank 14. Undissolued solids, particularly ~ine ore, will collect as a solios-containing phase in the bottom portion!of the tank 14 and together with the solids fro~ the bin 7 are recycled in line 15 to the sintering plant 1.
The substantial1y solids-free salt solutiQn wnicn is form~d in the settling tank 14 is con~ucted in lino 17 and ~. . . .
.
: , ,. :........ ..
preferably initially to a precipita~ing plant 1~, in which heavy metals are separated. In the plant 1~ the heavy metals are converted to insoluble campounds, e.g., by an addition of precipitants, and are separateo. Separated heavy metals are withdrawn in line 2~ and in most cases are dumped. The salt solution from which th2 heavy metals have substantially been removed is supplied in a line 21 to a spray drier 22 and is sprayed therein.
The spray dryer 22 i5 supplied via line 24 with a partial stream of the hot exhaust gas from the sintering plant. That partial stream of exhaust gaq i9 usually at a temperature in the range from Z00 to 400C. That partial stream of exhaust gas i9 preferably withdrawn from the hottest region of the sintering plant ~, the suction boxes 3a of which are disposed in the last one-third of the sintering plant. In the spray dryer 22, the hot exhaust gases from line 24 take up the moisture of the solution ~hich comes from the line 21 and has been sprayed. As a result, substantially dried salts sub-side to the bottom of the spray dryer and are withdrawn through the line Z5. The exhaust gases which contain water vapor l~ave the spray dryer 22 through the line Z6 and are subjected to a coarse dedusting in a cyclone 27 and are subsPquently con-ducted in line 2~ and admixed to the hot gases in line 5. The solids which are withdrawn from the cyclone 27 in line 29 are preferably also recycled to the sintering olant 1. If the de-dusting cyclone 27 may be omitte~, the exhaust gases are , ': ' ' ' , '., ' . ' ~ 1329~
:
directly supplied to the electrostatic precipitator via the by-pass line 28a and the line 28.
That region of the electrostatic precipitator 6 ~hich i~ adjacent to the gas outlet may be designed as a ~et-process electrastatic precipitator. In that case that region of the precipitator is provided with a ~ater inlet 30 for a supply of water which is sprayed in the associated region oF
the precipitator~ The separated solids w~ll cole~t as a sludge in the associated bin B. A supply of additional water in line 1Z may not be requried. The sludge is processed in the settling tank 14 as has been described.
EXAMPLE
` In a plant which was as shown in the orawing but in which the heavy metal separator 18 and the cyclone 2~ ~ere ~ omitted, a mixture which contains fine iron ore, fluxes and -~ fine coke and has a content of CaO and SiO2 in a ~eight ratio of 1.8 (basicity) i~ supplied in line Z to the sintering plant 1. The slntering plant has a suction area of ZBO mZ and pro-duces an exhaust gas at a total rate of ~oo~ooa sm3fh (sm3 =
standard cubic meter). That ga3 is at a temperature of 134C, and has a water dew point temperature oF 40~C and a dust content o~ 1 g/m3 as it enters the electrostatic precipi~ator 6. ~00 kg ' dust per hour are supplied to the electrostatic precipitator in ;~ the exhaust gas.
; Dust at a rate of 300 kg~h is collected in the , last bin B of the eiectrostatic p~ecipitator and cnntains 62%
.~ .
,. . .
.
- ~. -.. ,~ . . '' ,. ' : . .
.
~.
'~
. r~
2gl4L9 by weight of Roluble ~alts, particularly KCl and NaCl. Water at a rate of 1900 kg/h i9 added to that dust, which i9 then supplied to the settling tank 14. A chlnride-containing 90-lution at a rate of about 2000 kg/h is ~upplied to the spray dryer 22, ~hich is supplied in line Z4 at a rate of about 30,D00 sm3/h wlth an exhaust gas at a temperature af 2709C.
The residual moisture content oF the salt in line Z5 i9 about 3% by weight. The e~hau3t gas in line 28 has a temperature of 140C. ~ecause a ma~or part of the chlorides is separated in the spray dryer 22, the puri~ied exhaust gas in the chimney 11 has a dust content of only 30 mg /sm3 although a major part of the solids which have been separated in the electrostatic precipitator are recycled.
.
!
, , ;
;
, , . .
", .
Claims (4)
1. A process of purifying the exhaust gases from a sintering plant, wherein the exhaust gases are passed through an electrostatic precipitator to separate a dust mixture which contains chlorides and which is recycled in part to the sintering plant, characterized in that a solvent is added to at least part of the dust mixture and the chlorides are dissolved, solids are separated from the solution, the solvent is directly contacted in a spray dryer with hot exhaust gas from the sintering plant, substantially dried chlorides are removed from the spray dryer, and the solvent-containing exhaust gas from the spray dryer, is supplied to the electrostatic precipitator.
2. A process according to claim 1, characterized in that water is used as a solvent.
3. A process according to claim 1, characterized in that heavy metals are separated from the chloride-containing solution before it enters the spray dryer.
4. A process according to claim 2 or 3, characterized in that water is sprayed into the electrostatic precipitator adjacent to the gas outlet.
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
DEP3826500.1 | 1988-08-04 | ||
DE19883826500 DE3826500A1 (en) | 1988-08-04 | 1988-08-04 | METHOD FOR PURIFYING THE EXHAUST GAS FROM A SINTERING PLANT |
Publications (1)
Publication Number | Publication Date |
---|---|
CA1329149C true CA1329149C (en) | 1994-05-03 |
Family
ID=6360228
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
CA 607459 Expired - Fee Related CA1329149C (en) | 1988-08-04 | 1989-08-03 | Process of purifying the exhaust gases from a sintering plant |
Country Status (5)
Country | Link |
---|---|
EP (1) | EP0354613B1 (en) |
JP (1) | JPH0283045A (en) |
KR (1) | KR900002828A (en) |
CA (1) | CA1329149C (en) |
DE (2) | DE3826500A1 (en) |
Families Citing this family (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
IT1243120B (en) * | 1990-06-21 | 1994-05-24 | Servizi Costieri Srl | PROCEDURE FOR THE TREATMENT OF THE FINE PARTICULATE FROM ELECTRIC FILTERS OF POWER PLANTS SUPPLIED BY MINERAL OIL. |
DE19911168A1 (en) * | 1999-03-12 | 2000-09-14 | Abb Patent Gmbh | Process and arrangement for the treatment of chloride-containing dust |
KR100469589B1 (en) * | 2001-05-30 | 2005-02-02 | 유정근 | Method for removing Cl components from slag and/or dust |
CN112403255A (en) * | 2020-10-26 | 2021-02-26 | 攀枝花市蓝鼎环保科技有限公司 | Sintering flue gas treatment method |
Family Cites Families (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
GB1035667A (en) * | 1963-04-11 | 1966-07-13 | Metallgesellschaft Ag | The removal of dust from the waste gases of sintering installations |
US3444668A (en) * | 1964-03-06 | 1969-05-20 | Onoda Cement Co Ltd | Apparatus for electrostatic precipitation of dust |
-
1988
- 1988-08-04 DE DE19883826500 patent/DE3826500A1/en not_active Withdrawn
-
1989
- 1989-07-29 DE DE8989202002T patent/DE58900984D1/en not_active Expired - Lifetime
- 1989-07-29 EP EP19890202002 patent/EP0354613B1/en not_active Expired - Lifetime
- 1989-08-03 KR KR1019890011124A patent/KR900002828A/en active IP Right Grant
- 1989-08-03 CA CA 607459 patent/CA1329149C/en not_active Expired - Fee Related
- 1989-08-04 JP JP1202717A patent/JPH0283045A/en active Pending
Also Published As
Publication number | Publication date |
---|---|
JPH0283045A (en) | 1990-03-23 |
KR900002828A (en) | 1990-03-23 |
EP0354613B1 (en) | 1992-03-18 |
DE58900984D1 (en) | 1992-04-23 |
EP0354613A1 (en) | 1990-02-14 |
DE3826500A1 (en) | 1990-02-08 |
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