GB2091135A - Method of and apparatus for treating liquors by magnetic filtration - Google Patents
Method of and apparatus for treating liquors by magnetic filtration Download PDFInfo
- Publication number
- GB2091135A GB2091135A GB8132696A GB8132696A GB2091135A GB 2091135 A GB2091135 A GB 2091135A GB 8132696 A GB8132696 A GB 8132696A GB 8132696 A GB8132696 A GB 8132696A GB 2091135 A GB2091135 A GB 2091135A
- Authority
- GB
- United Kingdom
- Prior art keywords
- liquor
- magnetic
- solution potential
- vessel
- reducing agent
- 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.)
- Granted
Links
- 230000005291 magnetic effect Effects 0.000 title claims abstract description 42
- 238000001914 filtration Methods 0.000 title claims abstract description 21
- 238000000034 method Methods 0.000 title claims description 23
- 239000003638 chemical reducing agent Substances 0.000 claims abstract description 15
- CWYNVVGOOAEACU-UHFFFAOYSA-N Fe2+ Chemical compound [Fe+2] CWYNVVGOOAEACU-UHFFFAOYSA-N 0.000 claims abstract description 14
- 239000000523 sample Substances 0.000 claims abstract description 12
- 150000001875 compounds Chemical class 0.000 claims description 9
- GEHJYWRUCIMESM-UHFFFAOYSA-L sodium sulfite Chemical compound [Na+].[Na+].[O-]S([O-])=O GEHJYWRUCIMESM-UHFFFAOYSA-L 0.000 claims description 8
- VTLYFUHAOXGGBS-UHFFFAOYSA-N Fe3+ Chemical compound [Fe+3] VTLYFUHAOXGGBS-UHFFFAOYSA-N 0.000 claims description 6
- 238000012544 monitoring process Methods 0.000 claims description 6
- 239000003153 chemical reaction reagent Substances 0.000 claims description 5
- 229940075397 calomel Drugs 0.000 claims description 4
- ZOMNIUBKTOKEHS-UHFFFAOYSA-L dimercury dichloride Chemical compound Cl[Hg][Hg]Cl ZOMNIUBKTOKEHS-UHFFFAOYSA-L 0.000 claims description 4
- 229910001447 ferric ion Inorganic materials 0.000 claims description 4
- 235000010265 sodium sulphite Nutrition 0.000 claims description 4
- 230000005294 ferromagnetic effect Effects 0.000 claims description 3
- 150000002500 ions Chemical class 0.000 claims description 3
- 239000011159 matrix material Substances 0.000 claims description 3
- 238000005555 metalworking Methods 0.000 claims description 3
- 229910000510 noble metal Inorganic materials 0.000 claims description 3
- 239000003513 alkali Substances 0.000 claims description 2
- 230000001939 inductive effect Effects 0.000 claims description 2
- 229910052751 metal Inorganic materials 0.000 claims description 2
- 239000002184 metal Substances 0.000 claims description 2
- XEEYBQQBJWHFJM-UHFFFAOYSA-N iron Substances [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 abstract description 21
- 229910052742 iron Inorganic materials 0.000 abstract description 11
- SZVJSHCCFOBDDC-UHFFFAOYSA-N iron(II,III) oxide Inorganic materials O=[Fe]O[Fe]O[Fe]=O SZVJSHCCFOBDDC-UHFFFAOYSA-N 0.000 abstract description 8
- 229960004887 ferric hydroxide Drugs 0.000 abstract description 7
- IEECXTSVVFWGSE-UHFFFAOYSA-M iron(3+);oxygen(2-);hydroxide Chemical compound [OH-].[O-2].[Fe+3] IEECXTSVVFWGSE-UHFFFAOYSA-M 0.000 abstract description 7
- 239000000356 contaminant Substances 0.000 abstract description 3
- 230000001376 precipitating effect Effects 0.000 abstract description 2
- 239000003795 chemical substances by application Substances 0.000 abstract 1
- 230000000694 effects Effects 0.000 abstract 1
- -1 iron ions Chemical class 0.000 abstract 1
- 238000005259 measurement Methods 0.000 abstract 1
- 239000000243 solution Substances 0.000 description 19
- WCUXLLCKKVVCTQ-UHFFFAOYSA-M Potassium chloride Chemical compound [Cl-].[K+] WCUXLLCKKVVCTQ-UHFFFAOYSA-M 0.000 description 6
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 4
- 239000001301 oxygen Substances 0.000 description 4
- 229910052760 oxygen Inorganic materials 0.000 description 4
- 239000000463 material Substances 0.000 description 3
- 235000011164 potassium chloride Nutrition 0.000 description 3
- 239000001103 potassium chloride Substances 0.000 description 3
- 230000002285 radioactive effect Effects 0.000 description 3
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 description 2
- OAKJQQAXSVQMHS-UHFFFAOYSA-N Hydrazine Chemical compound NN OAKJQQAXSVQMHS-UHFFFAOYSA-N 0.000 description 2
- 239000011521 glass Substances 0.000 description 2
- JEIPFZHSYJVQDO-UHFFFAOYSA-N iron(III) oxide Inorganic materials O=[Fe]O[Fe]=O JEIPFZHSYJVQDO-UHFFFAOYSA-N 0.000 description 2
- QSHDDOUJBYECFT-UHFFFAOYSA-N mercury Chemical compound [Hg] QSHDDOUJBYECFT-UHFFFAOYSA-N 0.000 description 2
- 229910052753 mercury Inorganic materials 0.000 description 2
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Chemical compound [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 description 2
- 239000007787 solid Substances 0.000 description 2
- 239000002351 wastewater Substances 0.000 description 2
- 239000002253 acid Substances 0.000 description 1
- 229910021529 ammonia Inorganic materials 0.000 description 1
- 238000010923 batch production Methods 0.000 description 1
- 230000005587 bubbling Effects 0.000 description 1
- 238000004140 cleaning Methods 0.000 description 1
- 239000013078 crystal Substances 0.000 description 1
- 238000000605 extraction Methods 0.000 description 1
- 239000000706 filtrate Substances 0.000 description 1
- 239000007789 gas Substances 0.000 description 1
- 229910001385 heavy metal Inorganic materials 0.000 description 1
- 239000003295 industrial effluent Substances 0.000 description 1
- 239000010842 industrial wastewater Substances 0.000 description 1
- 235000000396 iron Nutrition 0.000 description 1
- 229910021506 iron(II) hydroxide Inorganic materials 0.000 description 1
- NCNCGGDMXMBVIA-UHFFFAOYSA-L iron(ii) hydroxide Chemical compound [OH-].[OH-].[Fe+2] NCNCGGDMXMBVIA-UHFFFAOYSA-L 0.000 description 1
- 230000003647 oxidation Effects 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- 230000005298 paramagnetic effect Effects 0.000 description 1
- 239000002244 precipitate Substances 0.000 description 1
- 238000001556 precipitation Methods 0.000 description 1
- 238000011084 recovery Methods 0.000 description 1
- 238000009877 rendering Methods 0.000 description 1
- 239000012047 saturated solution Substances 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
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
- B03C1/00—Magnetic separation
- B03C1/005—Pretreatment specially adapted for magnetic separation
- B03C1/015—Pretreatment specially adapted for magnetic separation by chemical treatment imparting magnetic properties to the material to be separated, e.g. roasting, reduction, oxidation
-
- 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
- B03C1/00—Magnetic separation
- B03C1/002—High gradient magnetic separation
Landscapes
- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- General Chemical & Material Sciences (AREA)
- Water Treatment By Electricity Or Magnetism (AREA)
- Removal Of Specific Substances (AREA)
Abstract
Treatment of liquors by magnetic filtration is made effectively by accurately controlling the ferrous/ferric ratio of iron ions in the liquor by adding a reducing agent. This has the effect that when the iron is precipitated, it is precipitated in the form of magnetite which is susceptible to high efficiency magnetic filtration. In the absence of control of the ratio, between 0.4 and 0.6, ferrous or ferric hydroxide might be precipitated and this is difficult to handle. Other contaminants are coprecipitated with or adsorbed by the iron floc. Measurement of the solution potential, between 0.35 and 0.4 volts, is used to determine the ferrous/ferric ratio. The apparatus includes a treatment vessel 2 with a solution potential probe 5, supply lines 3 for reducing agent and 4 for precipitating agent, and a magnetic filter 7. <IMAGE>
Description
SPECIFICATION
Method of and apparatus for treating liquors by magnetic filtration
This invention relates to a method of and apparatus for treating liquors by magnetic filtration.
High gradient magnetic filtration is a method of cleaning a wide range of industrial effluents and process liquors, particularly useful where the solids being removed need to be recovered with good efficiency or where recovery of solids in a minimum volume is required, for example in radioactive operations.
United Kingdom patent specification 1457528 relates to improvements in or relating to the extraction of heavy metals from industrial waste waters. The process described relies on knowledge of the amount of acid radicals within the waste water and the bubbling of oxidising gas into the waste water.
Also, examples of solutions within the specification indicate that the method is applicable to amounts of the order of 100 cc and one litre.
An object of the present invention is to provide a simple method of and apparatus for treating liquors by magnetic filtration whereby process quantities of liquor may be handled.
According to one aspect of the present invention, a method of treating liquors by magnetic filtration comprises:
adding reducing agent to the liquor,
monitoring solution potential of the liquor until a desired range of ratio of ferrous to ferric ions is reached whereat the solution potential falls within a desired range, adding alkali to precipitate outferruginous compounds, and
subjecting the liquor to magnetic filtration to remove said ferruginous compounds together with other compounds co-precipitated with or adsorbed by the ferruginous floe.
Preferably, said desired range of ferrous to ferric ions is forty percent to sixty percent. Preferably, reducing agent is added until the solution potential is in the range of between 0.35 and 0.4 volts.
The reducing agent may comprise hydrazene or it may comprise sodium sulphite.
According to another aspect of the present invention, apparatus for treating liquors by magnetic filtration comprises;
a treatment unit comprising a liquor handling vessel through which liquor may be fed, said vessel including means whereby reagent can be added to the vessel and means for monitoring solution potential of the liquor in the vessel, and
a magnetic filter.
Preferably, the means for monitoring solution potential of liquor in the vessel comprises a solution potential probe. The solution potential probe may comprise a calomel reference electrode and a noble metal working electrode, EMF developed between said electrodes being the solution potential, the solution potential being a function ofthe oxidisation state of ferruginous ions in the vessel.
The magnetic filter may comprisea a unit which contains a ferro-magnetic matrix. The magnetic filter may contain an array of metal rods. The magnetic filter may contain an array of grids. Preferably, means is provided adjacent to the magnetic filter for inducing a high magnetic field across it.
An embodiment of the present invention will now be described by way of example only, with referece otthe accompanying drawings, in which:
Figure 1 is a diagrammatic view of plant for treating liquors by magnetic filtration,
Figure 2 is a sectional view of a probe for use in the plant of Figure 1, and
Figure 3 is a graph showing operational parameters occurring in the plant.
Reference is directed firstly to Figure 1, in which an input line for a liquor to be treated by magnetic filtration is generally indicated by 1. The liquor is fed via the input line 1 to a treatment unit 2 comprising a liquor handling vessel. Reagent lines 3 and 4 are also fed to the treatment unit 2. The treatment unit 2 contains a probe 5, which will be described in more detail below. In the treatment unit, the liquor is first treated by the addition of a reducing agent along line 3. Treatment continues, until the probe 5 indicates that the liquor has reached a condition which falls within a desired range as will be explained below.
Following addition of the reducing agent, the liquor is then reacted with alkalis in order to precipitate out ferruginous compounds and co-precipitated compounds together with compounds as adsorbed by the ferruginous floe. Following treatment in the unit 2, the liquor is fed out along line 6 into a magnetic filter 7.
The magnetic filter 7 comprises an assembly which contains a ferro-magnetic matrix 8, for example, a wire mesh arrangement, an array of rods, a grid 10 or an arrangement of packed spheres. The magnetic filter 7 can be subjected to a high magnetic field, said field being generated by means 12 disposed adjacent to the magnetic filter. After filtering, the filtrate leaves the filters along line 14. From time to time, the filter can be backwashed along lines 16 and 17. In order to facilitate this operation, valves 18 are provided in lines 6, 14, 16 and 17.
Reference is now directed to Figure 2 which shows the probe 5 referred to above in connection with
Figure 1 in more detail. The probe 5 comprises a calomel reference electrode 20 and a noble metal working electrode 21. The electrode 20 comprises a glass tube 23 which contains crystals of potassium chloride 24 in a saturated solution of potassium chloride 25. Electrical contact is made with the solution of potassium chloride via porous sintered glass frit plugs 26 and 27. The plug 27 closes a tube which contains a paste of calomel and mercury 28 in contact with a lead of mercury 29 and a platinum wire 30. The electrode 21 is a platinum wire electrode.
Operation of the equipment is now described with reference to Figure 3. All materials which are paramagnetic can be removed from effluent streams or process liquors using a high grade magnetic filtration system provided the magnetic gradient is high enough and the effluent flow rate is slow enough. For materials of low magnetic susceptibility, a capital cost of a satisfactory system can be very high rendering the system unattractive and uneconomic. Ferric hydroxide is a commonly-found major component of suspended material present in many effluent and process liquors and it is difficu It to remove by conventional filters because of its gelatinous nature. Settling is also unattractive because ferric hydroxide retains large amounts of water and requires excessively large handling systems.
However, the precipitation of ferric hydroxide from an effluent can in many cases be helpful in effecting the removal of other contaminant which are adsorbed on the surface of the floc or co-precipitated and carried down with it. This is particularly useful with radioactive contaminants.
Unfortunately, ferric hydroxide is only weakly susceptible to being magnetised in a magnetic field and therefore is not attracted with high efficiency to magnetised components in the filter 7. Therefore, in order that the filtration exercise can become more successful, ferruginous ions are converted to the form of magnetite (usually denoted by Fe3O4), which is more susceptible to the magnetic gradient of the filter and gives higher collecting efficiencies.
Reference is now directed to Figure 3, in which solution potential as determined by the probe 5 in the treatment unit 2 is plotted as ordinate in millivolts. The abscissa of the graph is quantity of reducing agent, in this case sodium sulphite, added to the unit 2 along line 3. The abscissa is plotted in arbitrary units. The graph shows five curves, which curves represent iron concentration in parts per million of 50, 100, 150, 300 and 600, which are indicated by curves A, B, C, D and E, respectively. A hatched part of the graph indicates a range of solution potential between .35 and .4volts. In this range, the ratio of ferrous to ferric irons is between 0.4 and 0.6, for all of the iron concentrations.
In operation of the equipment, part of the dissolved oxygen content of the liquor stream is removed and iron reduced to the critical ferrous ferric ration in the range of .4 to .6 in the unit 2 (the oxygen content being less than 0.05 parts per million). When the oxygen content is removed and the desired part of the iron is reduced in order to give this critical ferrous/ferric ratio, the iron is precipitated out of the liquor in the form of magnetite by the addition of ammonia along line 4. The oxygen can be removed and part of the iron reduced by any one of several reagents such as sodium sulphite and hydrazine, but excess reducing agent is avoided, since if excess reagent were to be used, the iron would be reduced totally to its ferrous state which then precipitates in the form of gelatinous ferrous hydroxide, which is even more difficult to handle than ferric hydroxide.
On the steady addition of reducing agent to the process liquor, which is well stirred, the solution potential begins to fall smoothly from its usual value for the fuily oxidised state of between 0.5 to 0.55 volts. At a solution potential of 0.25 volts fall in EMF (electro motive force) begins to increase indicating that the majority of the ferric iron has been reduced to the ferrous state. Thus, the solution potential is a function of the oxidation state of the iron in solution.
Therefore, by adding reducing agent until the solution potential is between 0.4 and 0.35 volts, the ferrous/ferric ratio is made to fall between .4 and .6.
Operation is optimised when the ratio is .5.
In view of the operation of the apparatus, the liquor which is fed to the magnetic filter 7 contains magnetite and does not have significant quantities of either ferrous or ferric hydroxide, so that the filter 7 operates effectively to filter the magnetite which is attracted to the collecting means so that the liquor is efficiently filtered.
It is to be understood, that the probe 5 described above is able to generate a voltage because of the different electro chemical potential of solution 24 to the process liquor.
Also, the process is applicable to streams where ferric iron in absent, but wherein it is added by deliberate addition so that it can be precipitated in the form of magnetite and other components can be co-precipitated and thereby more readily removed.
This can be advantageous in dealing with radioactive effluents.
It is further to be understood that the process described above is able to handle of the order of one cubic metre per minute of liquor. The unit 2 operates in a batch process, in some embodiments, it may be internally divided to split the reducing and precipitating stages.
From the foregoing, it will be appreciated that the present invention provides and improved method of and apparatus for treating liquors by magnetic filtration.
Claims (14)
1. A method of treating liquors by magnetic filtration comprising:
adding reducing agent to the liquor,
monitoring solution potential of the liquor until a desired range of ratio of ferrous to ferric ions is reached whereat the solution falls within a desired range,
adding alkali to precipitate outferruginous compounds, and
subjecting the liquor to magnetic filtration to remove said ferruginous compounds together with other compounds co-precipitated with or absorbed by the ferruginous floc.
2. A method as claimed in claim 1, in which said desired range of ferrous to ferric ions is forty percent to sixty percent.
3. A method as claimed in claim 1, in which reducing agent is added until the solution potential is in a range of between 0.35 and 0.4 volts.
4. A method as claimed in claim 1, in which the reducing agent comprises hydrazene.
5. A method as claimed in claim 1, in which the reducing agent comprises sodium sulphite.
6. Apparatus for treating liquors by magnetic filtration comprising:
a treatment unit comprising a liquor handling vessel through which liquor may be fed, said vessel including means whereby reagent can be added to the vessel and means for monitoring solution potential of the liquor in the vessel, and a magnetic filter.
7. Apparatus as claimed in claim 6, in which the means for monitoring solution potential of liquor in the vessel comprises a solution potential probe.
8. Apparatus as claimed in claim 7, in which the solution potential probe comprises a calomel reference electrode and a noble metal working electrode,
EMF developed between said electrodes being the solution potential, the solution potential being a function of the oxidisation state of ferruginous ions in the vessel.
9. Apparatus as claimed in claim 6, in which the magnetic filter comprises a unit which contains a ferromagnetic matrix.
10. Apparatus as claimed in claim 9, in which the magnetic filter contains an array of metal rods.
11. Apparatus as claimed in claim 9, in which the magnetic filter contains an array of grids.
12. Apparatus as claimed in claim 6, in which means is provided adjacent to the magnetic filter for inducing a high magnetic field across it.
13. A method of treating liquor for magnetic filtration substantially as hereinbefore described and as shown in the accompanying drawings.
14. Apparatus for treating liquor for magnetic filtration substantially as hereinbefore described and as shown in the accompanying drawings.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB8038256 | 1980-11-28 | ||
| GB8100985 | 1981-01-13 |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| GB2091135A true GB2091135A (en) | 1982-07-28 |
| GB2091135B GB2091135B (en) | 1984-10-17 |
Family
ID=26277659
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB8132696A Expired GB2091135B (en) | 1980-11-28 | 1981-10-29 | Method of and apparatus for treating liquors by magnetic filtration |
Country Status (5)
| Country | Link |
|---|---|
| AU (1) | AU555909B2 (en) |
| DE (1) | DE3146953A1 (en) |
| FR (1) | FR2495019B1 (en) |
| GB (1) | GB2091135B (en) |
| IT (1) | IT1145127B (en) |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2151511A (en) * | 1983-12-22 | 1985-07-24 | Dr James Henry Peter Watson | Method of magnetically filtering radioactive particles from air or other fluids |
| GB2175916A (en) * | 1985-06-01 | 1986-12-10 | British Petroleum Co Plc | Removing mineral matter from solid carbonaceous fuels |
| US4735707A (en) * | 1985-06-01 | 1988-04-05 | The British Petroleum Company P.L.C. | Removing mineral matter from solid carbonaceous fuels |
| CN115286126A (en) * | 2021-04-15 | 2022-11-04 | 国家能源投资集团有限责任公司 | Sewage treatment method |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE19545660C1 (en) * | 1995-12-07 | 1997-04-10 | Karlsruhe Forschzent | Removing heavy metals from waste water using ferri- or ferromagnetic particles |
Family Cites Families (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5111038B2 (en) * | 1973-02-10 | 1976-04-08 | ||
| JPS5714919B2 (en) * | 1973-07-06 | 1982-03-27 | ||
| DE2551030C3 (en) * | 1974-11-15 | 1979-11-15 | Miura Engineering International Co. Ltd., Osaka (Japan) | Wastewater treatment device with a device with magnets rotating around a shaft |
| ES444739A1 (en) * | 1975-10-01 | 1977-08-16 | Anglo American Clays Corp | Magnetic beneficiation of clays utilizing magnetic particulates |
-
1981
- 1981-10-29 GB GB8132696A patent/GB2091135B/en not_active Expired
- 1981-11-09 AU AU77197/81A patent/AU555909B2/en not_active Ceased
- 1981-11-19 IT IT68503/81A patent/IT1145127B/en active
- 1981-11-26 DE DE19813146953 patent/DE3146953A1/en not_active Withdrawn
- 1981-11-27 FR FR8122306A patent/FR2495019B1/en not_active Expired
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2151511A (en) * | 1983-12-22 | 1985-07-24 | Dr James Henry Peter Watson | Method of magnetically filtering radioactive particles from air or other fluids |
| GB2175916A (en) * | 1985-06-01 | 1986-12-10 | British Petroleum Co Plc | Removing mineral matter from solid carbonaceous fuels |
| US4735707A (en) * | 1985-06-01 | 1988-04-05 | The British Petroleum Company P.L.C. | Removing mineral matter from solid carbonaceous fuels |
| CN115286126A (en) * | 2021-04-15 | 2022-11-04 | 国家能源投资集团有限责任公司 | Sewage treatment method |
Also Published As
| Publication number | Publication date |
|---|---|
| AU555909B2 (en) | 1986-10-16 |
| IT8168503A0 (en) | 1981-11-19 |
| IT1145127B (en) | 1986-11-05 |
| AU7719781A (en) | 1982-06-03 |
| DE3146953A1 (en) | 1982-06-03 |
| FR2495019B1 (en) | 1985-09-13 |
| FR2495019A1 (en) | 1982-06-04 |
| GB2091135B (en) | 1984-10-17 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PCNP | Patent ceased through non-payment of renewal fee |