EP0165945A1 - Method of improving the purity of alkali-metal hydroxides - Google Patents
Method of improving the purity of alkali-metal hydroxidesInfo
- Publication number
- EP0165945A1 EP0165945A1 EP85900029A EP85900029A EP0165945A1 EP 0165945 A1 EP0165945 A1 EP 0165945A1 EP 85900029 A EP85900029 A EP 85900029A EP 85900029 A EP85900029 A EP 85900029A EP 0165945 A1 EP0165945 A1 EP 0165945A1
- Authority
- EP
- European Patent Office
- Prior art keywords
- alkali
- metal
- alkaline
- compounds
- solution
- 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.)
- Withdrawn
Links
Classifications
-
- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21C—PRODUCTION OF CELLULOSE BY REMOVING NON-CELLULOSE SUBSTANCES FROM CELLULOSE-CONTAINING MATERIALS; REGENERATION OF PULPING LIQUORS; APPARATUS THEREFOR
- D21C11/00—Regeneration of pulp liquors or effluent waste waters
- D21C11/12—Combustion of pulp liquors
- D21C11/122—Treatment, e.g. dissolution, of the smelt
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01D—COMPOUNDS OF ALKALI METALS, i.e. LITHIUM, SODIUM, POTASSIUM, RUBIDIUM, CAESIUM, OR FRANCIUM
- C01D1/00—Oxides or hydroxides of sodium, potassium or alkali metals in general
- C01D1/04—Hydroxides
- C01D1/28—Purification; Separation
- C01D1/32—Purification; Separation by absorption or precipitation
-
- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21C—PRODUCTION OF CELLULOSE BY REMOVING NON-CELLULOSE SUBSTANCES FROM CELLULOSE-CONTAINING MATERIALS; REGENERATION OF PULPING LIQUORS; APPARATUS THEREFOR
- D21C11/00—Regeneration of pulp liquors or effluent waste waters
- D21C11/0064—Aspects concerning the production and the treatment of green and white liquors, e.g. causticizing green liquor
- D21C11/0078—Treatment of green or white liquors with other means or other compounds than gases, e.g. in order to separate solid compounds such as sodium chloride and carbonate from these liquors; Further treatment of these compounds
Definitions
- This invention relates to a method of increasing the purity of alkali-metal hydroxides.
- Sodium hydroxide and other alkali-metal hydroxides produced by known means may contain, as well as some carbonate, inorganic contaminants derived from a variety of sources associated with the manufacture, storage, use or regeneration of those hydroxides. These sources of contaminants include raw materials, chemical reagents, water supplies and materials of construction of industrial plant.
- sources of contaminants include raw materials, chemical reagents, water supplies and materials of construction of industrial plant.
- the alkali-metal hydroxide is manufactured or regenerated by a process in which material comprising or containing alkali-metal carbonate, alkali-metal bicarbonate or alkali-metal organic salt or salts is heated together with an amphoteric oxide of a transition metal to obtain a salt or mixed oxide of general formula (M-0) .
- M an alkali-metal (e.g. Na, K) and R is a transition metal (e.g. Ti, Fe)
- said salt or mixed oxide then being hydrolysed to yield the alkali-metal hydroxide.
- the method of the invention is applicable particularly to Prior Art Category A although not exclusively thereto.
- This present invention is applicable y ⁇ t more particularly although again not exclusively when an embodiment of Prior Art Category A is employed for the regeneration of sodium hydroxide from the spent liquors (e.g. black liquor) resulting from sulphur-free alkaline pulping of wood or of other lignocellulosic material and where the transition-metal amphoteric oxide used in said regeneration is ferric oxide.
- spent liquors e.g. black liquor
- transition-metal amphoteric oxide used in said regeneration is ferric oxide.
- the sodium hydroxide solution usually contains a minor proportion " of unreacted sodium carbonate.
- the combustion during the firing stage is assumed to convert organic salts of sodium into sodium carbonate which , together with the sodium carbonate initially present in the spent pulping liquor then reacts with the ferric oxide to form predominantly ⁇ -sodium ferrite and carbon dioxide gas. This latter reaction is represented by the equation:-
- the transition-metal amphoteric oxide may make a particularly substantial contribution of inorganic contaminants, possibly rendering the product undesirable or unsuitable for use in certain applications.
- the chemical elements present as contaminants in the alkali-metal hydroxide may be at least in part in soluble or colloidally-dispersed forms not readily amenable to purely mechanical me «ns of removal such as filtration and may include the transition-metal whose amphoteric oxide is used and also elements originally present as impurities in that - + -
- transition-metal • amphoteric oxide Impurities in the transition-metal • amphoteric oxide may be particularly abundant when this is in the form of a naturally-occurring ore (e.g. hematite, ilmenite) , even if that ore has undergone a degree of beneficiation.
- a naturally-occurring ore e.g. hematite, ilmenite
- An ability to use naturally-occurring ores is desirable because these are cheaper than synthetic or highly purified forms of the transition-metal amphoteric oxides.
- Aluminium, silicon, iron and manganese are among elements "that may be present in sufficiently large amounts as contaminants in alkali-metal hydroxide obtained via Prior Art Category A to be undesirable when the alkali-metal hydroxide is used in applications such as the manufacture of papermaking pulp from lignocellulosic materials, the manufacture of rayon or the manufacture of soap.
- aluminium and silicon can form sludges and scale deposits containing minerals such as cancrinite and analcite in heat-transfer equipment in contact with the spent pulping liquor.
- Iron and manganese may also incorporate in such mineral deposits but in addition may cause discolouration of the pulp, may catalyse oxidative degradation of the pulp fibres on aging or when oxygen is used as a reagent in the pulping or pulp-bleaching operations and may catalyse decomposition of hydrogen peroxide when this is used as a pulp-bleaching agent.
- the present invention concerns a method devised primarily to lessen the aluminium content of contaminated alkali-metal hydroxides, but we have found that application of the method may also effect a lessening of other contaminants including iron.
- This present invention is characterised by the minimisation of contaminants, which may be effected either by preventing contaminants from entering the - 9- - "
- solution of alkali-metal hydroxide as this is produced, or by removing contaminants from a contaminated solution- of alkali-metal hydroxide.
- the invention utilises alkaline earth compounds to render contaminants insoluble, thereby lessening the entry of contaminants into the solution of alkali-metal hydroxide, or promoting removal of contaminants from a contaminated solution of alkali-metal hydroxide.
- at least part of the contaminant content previously in dissolved or other difficultly separable forms in the solution is incorporated into a solid phase removable by filtration, sedimentation, centrifuging or like means of solid-liquid separation.
- Suitable alkaline earth compounds are the carbonates, basic carbonates, oxides, hydroxides or water-soluble organic or inorganic salts .of alkaline earths (e.g. of Mg, Ca, Sr, Ba) . A mixture of two or more of these compounds, or a compound within these categories, but containing more than one alkaline earth, may also be used.
- Magnesium is the alkaline earth in a preferred embodiment of this invention.
- the contaminants removable by the process of the invention include aluminium and iron.
- the form in which aluminium is rendered insoluble by application of this present invention when the alkaline-earth compound used- is one of magnesium is indicated by X-ray diffraction analysis to be predominantly hydrotalcite, whose .formula may be written as MggAl 2 (OH),gCO.-..4H 2 0.
- the compound of an "alkaline-earth and preferably of magnesium to be used according to this present invention may be introduced into or brought into contact with the alkali-metal hydroxide solution after this has been separated from the reformed amphoteric oxide, but in a particularly preferred embodiment of the invention may be introduced at an earlier stage so that it is present during and/or immediately after the hydrolysis operation, and its solid reaction product then accompanies the reformed amphoteric oxide when this is separated from the alkali-metal hydroxide solution.
- hydrotalcite contains carbonate, it is necessary that for aluminium to be removed in the form of this or analogous compounds of other alkaline earths a source of carbonate must be present during the application of the method of the invention. In the case of Prior Art Category A, the residual alkali-metal carbonate normally present is usually sufficient.
- magnesium oxide is the alkaline-earth compound used in a preferred embodiment of this present invention.
- Economical means of obtaining magnesium oxide suitable for use in that embodiment include the calcining of naturally-occurring carbonate minerals such as magnesite and dolomite.
- aluminium is rendered insoluble mainly by reaction of the magnesium oxide component rather than of the calcium oxide component.
- An alkali-metal hydroxide solution may be treated with the alkaline-earth compound at any temperature in the range from the freezing point up to and including the boiling point of said solution.
- a sodium hydroxide solution clarified by centrifuging and containing total sodium at 5.56 mole/kg and of 89.1 per cent causticity was produced from evaporated spent sulphur-free alkaline pulping liquor and hematite ore according to an embodiment of Prior Art Category A. Natural dolomite was calcined for two hours at 1100 C to give a granular product containing 25.2 per cent magnesium by mass and allowed to cool. - S -
- Portions of the sodium hydroxide solution each of approximately 80 g were heated to 80°C, mixed with different amounts of the calcined dolomite, immediately vigorously agitated for 30 minutes while maintaining the temperature at 80°C then filtered without prior cooling.
- a further similar-sized portion of the sodium hydroxide solution was treated in identical manner except that no calcined dolomite or other additive was used.
- a filtered sodium hydroxide solution containing total sodium " at 5.42 mole/kg and of 83.8 per cent causticity was produced from hematite ore and laboratory-grade sodium carbonate according to an embodiment of Prior Art Category A.
- a 33.85 g portion of this solution was heated to 80°C, mixed with 50.04 g of laboratory-grade magnesium sulphate heptahydrate, immediately vigorously agitated for 30 minutes while maintaining said temperature then filtered without prior cooling.
- a second similar-sized portion of the sodium hydroxide solution was treated identically except that no magnesium sulphate or other additive was used.
- a granular solid containing ⁇ -sodium ferrite and with an Fe:Na mole ratio of 1.42 was obtained according to an embodiment of Prior Art Category A by firing in air a mixture of evaporated spent sulphur-free alkaline pulping liquor and hematite ore and allowing the product to cool. Natural dolomite was calcined at 1100°C for two hours and allowed to cool, giving a granular solid containing 25.2 per cent magnesium by mass.
- One hundred grammes of the solid containing J-sodium ferrite were mixed with 4.40 g of the calcined dolomite and then with 60 ml of distilled water and continuously agitated for one hour at 80°C to hydrolyse the ferrite and leach out the resultant sodium hydroxide into solution. The sodium hydroxide solution was then filtered without prior cooling. A second and similar-sized portion of the solid containing sodium ferrite was treated identically except . that no calcined dolomite was used.
- Granular calcined dolomite of Example 1 was ground to powder.
- a 200.8-g portion of an impure sodium hydroxide solution of total sodium content 6.12 mol/kg and of causticity 83.6 per cent was heated to 100°C, mixed -with 2.53 g of the powdered calcined dolomite and immediately placed under continuous vigorous agitation while maintaining said temperature.
- samples of that solution were withdrawn from the reaction mixture through filters without prior cooling.
- a second portion of the impure sodium hydroxide solution was heated to 100°C and filtered with no addition of calcined dolomite or other additive.
Landscapes
- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Inorganic Chemistry (AREA)
- Compounds Of Alkaline-Earth Elements, Aluminum Or Rare-Earth Metals (AREA)
Abstract
Dans un procédé pour améliorer la pureté d'hydroxydes de métal alcalin, on utilise des composés de métal alcalino-terreux pour rendre les impuretés insolubles, diminuant ainsi la pénétration d'impuretés dans une solution d'hydroxyde de métal alcalin ou favorisant le retrait d'impuretés d'une solution contaminée d'hydroxydes de métal alcalin. La présente invention peut être appliquée en particulier pour augmenter la pureté d'hydroxydes de métal alcalin régénéré à partir de liqueur épuisée résultant de la pulpation alcaline exempte de soufre du bois ou la pureté d'un autre matériau naturel contenant des fibres cellulosiques.In a process for improving the purity of alkali metal hydroxides, alkaline earth metal compounds are used to make impurities insoluble, thereby decreasing the penetration of impurities into an alkali metal hydroxide solution or promoting the removal of impurities from a contaminated solution of alkali metal hydroxides. The present invention can be applied in particular to increase the purity of hydroxides of alkali metal regenerated from spent liquor resulting from the sulfur-free alkaline pulpation of wood or the purity of another natural material containing cellulose fibers.
Description
Claims
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
AU3009/83 | 1983-12-23 | ||
AUPG300983 | 1983-12-23 |
Publications (2)
Publication Number | Publication Date |
---|---|
EP0165945A1 true EP0165945A1 (en) | 1986-01-02 |
EP0165945A4 EP0165945A4 (en) | 1986-07-17 |
Family
ID=3770460
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP19850900029 Withdrawn EP0165945A4 (en) | 1983-12-23 | 1984-12-24 | Method of improving the purity of alkali-metal hydroxides. |
Country Status (8)
Country | Link |
---|---|
EP (1) | EP0165945A4 (en) |
JP (1) | JPS61500783A (en) |
AU (1) | AU3785285A (en) |
BR (1) | BR8407243A (en) |
FI (1) | FI853215A0 (en) |
IT (1) | IT1177487B (en) |
WO (1) | WO1985002834A1 (en) |
ZA (1) | ZA849901B (en) |
Families Citing this family (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPH0784716B2 (en) * | 1985-10-29 | 1995-09-13 | 三菱重工業株式会社 | Method for recovering caustic soda from alkaline pulp waste liquor |
CN115667622A (en) * | 2020-05-22 | 2023-01-31 | 苏扎诺公司 | Method of treating kraft process recovery cycle to reduce metal levels in kraft process |
Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
GB381697A (en) * | 1931-09-19 | 1932-10-13 | Erik Ludvig Rinman | Method of relieving alkaline waste liquors from the soda or sulphate pulp manufacture, of silica |
US2628155A (en) * | 1948-12-20 | 1953-02-10 | Gruen Bengt Herman Emanuel | Method for the recovery of spent liquors from the cooking of cellulose from raw material containing silica |
DE1076485B (en) * | 1958-01-29 | 1960-02-25 | Inst Zellstoff | Process for the removal of silica from alkaline cellulose waste liquors rich in silicate, especially in continuous operation |
Family Cites Families (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
GB335371A (en) * | 1929-07-15 | 1930-09-25 | Erik Ludvig Rinman | Method of alkalizing the waste liquors from the soda or sulphate pulp manufacture for the purpose of dry distilling the same |
AU450309B2 (en) * | 1972-11-13 | 1974-07-04 | Oji Paper Co. Ltd. | Method for directly converting sodium carbonate into caustic soda and application of said method to pulp and paper industry |
US4224289A (en) * | 1978-04-20 | 1980-09-23 | Australian Paper Manufacturers Limited | Alkali regeneration process |
CA1188485A (en) * | 1982-03-25 | 1985-06-11 | Kien L. Nguyen | Alkali regeneration process |
-
1984
- 1984-12-19 ZA ZA849901A patent/ZA849901B/en unknown
- 1984-12-21 IT IT24161/84A patent/IT1177487B/en active
- 1984-12-24 BR BR8407243A patent/BR8407243A/en unknown
- 1984-12-24 JP JP60500269A patent/JPS61500783A/en active Pending
- 1984-12-24 EP EP19850900029 patent/EP0165945A4/en not_active Withdrawn
- 1984-12-24 WO PCT/AU1984/000270 patent/WO1985002834A1/en not_active Application Discontinuation
- 1984-12-24 AU AU37852/85A patent/AU3785285A/en not_active Abandoned
-
1985
- 1985-08-21 FI FI853215A patent/FI853215A0/en not_active Application Discontinuation
Patent Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
GB381697A (en) * | 1931-09-19 | 1932-10-13 | Erik Ludvig Rinman | Method of relieving alkaline waste liquors from the soda or sulphate pulp manufacture, of silica |
US2628155A (en) * | 1948-12-20 | 1953-02-10 | Gruen Bengt Herman Emanuel | Method for the recovery of spent liquors from the cooking of cellulose from raw material containing silica |
DE1076485B (en) * | 1958-01-29 | 1960-02-25 | Inst Zellstoff | Process for the removal of silica from alkaline cellulose waste liquors rich in silicate, especially in continuous operation |
Non-Patent Citations (2)
Title |
---|
See also references of WO8502834A1 * |
TAPPI, vol. 68, no. 4, April 1985, pages 33,35, Easton, Penn., US; "The removal of aluminum from the recovery system of a closed kraft pulp mill" * |
Also Published As
Publication number | Publication date |
---|---|
WO1985002834A1 (en) | 1985-07-04 |
FI853215L (en) | 1985-08-21 |
BR8407243A (en) | 1985-11-26 |
JPS61500783A (en) | 1986-04-24 |
IT8424161A0 (en) | 1984-12-21 |
ZA849901B (en) | 1985-08-28 |
EP0165945A4 (en) | 1986-07-17 |
AU3785285A (en) | 1985-07-12 |
FI853215A0 (en) | 1985-08-21 |
IT1177487B (en) | 1987-08-26 |
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Legal Events
Date | Code | Title | Description |
---|---|---|---|
PUAI | Public reference made under article 153(3) epc to a published international application that has entered the european phase |
Free format text: ORIGINAL CODE: 0009012 |
|
AK | Designated contracting states |
Designated state(s): DE FR SE |
|
17P | Request for examination filed |
Effective date: 19851230 |
|
A4 | Supplementary search report drawn up and despatched |
Effective date: 19860717 |
|
17Q | First examination report despatched |
Effective date: 19870909 |
|
STAA | Information on the status of an ep patent application or granted ep patent |
Free format text: STATUS: THE APPLICATION IS DEEMED TO BE WITHDRAWN |
|
18D | Application deemed to be withdrawn |
Effective date: 19880120 |
|
RIN1 | Information on inventor provided before grant (corrected) |
Inventor name: GILLETT, JOHN, DAVID Inventor name: WUNDER, HEIKO Inventor name: SCUKOVIC, JACK Inventor name: BENNETT, ALLAN, JOHN |