Title of Invention

A PROCESS FOR REDUCING THE CONTENT OF CHLORIDE POTASSIUM AND OTHER METAL IN A RECOVERY SYSTEM

Abstract An increasing problem with the pulping chemical recovery system, is the presence of chloride and potassium in the recovery boiler. Chloride and potassium increase inter alia the stickiness of carryover deposits and dust particles to the recovery boiler tubes, which accelerate fouling, corrosion and plugging of the recovery boiler. As the environmental legisla¬tion becomes more stringent, the degree of system closure increases. The present invention relates to a process by which the collected precipitator dust is leached, at a temperature exceeding 50°C, for a residence time sufficient to get a chloride and potassium enriched leach solution and to remove at least a part of the content of metal ions in a solid phase. Said leach solution is electrochemically treated, preferably in an electrodialysis cell, in order to remove at least a part of the chloride and potassium therein. By the present process, the problem of sticky deposits in the recovery boiler can be substantially reduced. This means an improved energy effi¬ciency as well as a higher degree of recovery of the pulping and bleaching chemicals. PRICE: THIRTY RUPEES
Full Text



Leaching process
The present invention relates to an environmental-friendly process for reducing the content of chloride and metal ions in a liquid inventory of a chemical pulp mill.
In the production of a chemical pulp, chips of ligno-cellulose-containing material ar<:i conk. in an alkaline or acid aqueous solution. this cooking i i.quid contains inorganic pulping chemicals to improve the dissolution of lignin is normally carried out at a temperature above reduce residence time for pulp produced. therefore pressure vessel known as digester.> In the production of sulphat:- pulp, soda pulp and sulphite pulp with an alkali iivtal .is .1 base, normally sodium, it is possible to recover the inorganic pulping chemicals in the spent liquor leaving the digester. It is vital both to economy and environment to recover these pulping chemicals to the largest possible extent. This is achi.eved in the pulping chemical recovery system, which essent ially transfers the used inorganic pulping chemicals into a chemical state, where they can be re-used for cooking.
An essential part of the reeove y a/stem is the recovery boiler, where the spent liquor is burned. Normally, make-up chemicals are added to the spent: lienor before the recovery boiler to make up for the chemicals iost during cooking and recovery. The spent liquor is sprayei into the lower part of the boiler, previously at a re l.ati .-.'.'.1 y low temperature to remove free water. Modern recovery b'a lers operate at a high temperature to reduce the content, of aulphur in the flow gases leaving the boiler. Higher up in the boiler, gases and vapours of light hydrocarbons and decomposition products are volati¬lized. This is known as pyrolysis. Then, the pyrolysis products are burned after mixing with air or oxygen. The solid carbon-based residue which remains after complete pyrolysis of the organics is then heterogeneously burned. The solid parti¬cles formed are collected as a dust in precipitators at the top of the recovery boiler, to reduce the release of solid material to the surrounding atmosphere.
A substantial and increasing problem with the pulping

enemicai recovery system, is t.he presence of chloride and potassium in the spent liquor entering the recovery boiler. These elements tend to reduce the capacity of the recovery boiler to produce useful chemicals. Thus, chloride and potassium increase the stickiness of carryover deposits and dust particles to the recovery boiler tubes, which accelerate fouling and plugging in the upper part of the recovery boiler. Chloride also tend to increase the corrosion rate of superheater tubes.
Chloride and potassium are concentrated in the dust formed during the combustion of spent: liquor in the recovery boiler. The dust is collected in dry-bottom or wet-bottom electrostatic precipitators. TJU- ciust mainly consists of sodium and potassium salts, where sulphate, carbonate and chloride are the dominant anions. The amount of dust .corre¬sponds to about 5 to about lb:i by weight of the sodium enter¬ing the recovery boiler, which corresponds to about 50 to about 150 kg dust per ton pulp, Lf the dust is calculated as sodium sulphate.
Today, normally all of the precipitator dust collected and withdrawn from the recovery boiler is recycled to the flow of spent liquor to be burned in the boiler. When the concen¬tration of chloride or potassium is too high, a portion of the precipitator dust is withdrawn from the system and discharged or deposited.
The content of chloride in the spent liquor can be very high for coastal mills, if the raw material consists of logs floated in seawater. The content: is moderate in mills using caustic make-up contaminated with sodium chloride or in mills that at least partially recov-t sp-Mii bleach liquids from stages using chlorine-conta i n i n--r, the degree of system closure increases. This means that even a small input of chloride becomes a severe problem, unless the content can be controlled by purging the system In some environmentally acceptable way.
A further problem in the chemical, recovery system, in the treatment of spent liquet:; and recirculation of the

funiiea process liquids, is the content; of metal ions. In the treatment of the spent liquors, especially when using electro¬chemical methods, the metals are harmful. Metal ions such as calcium (Ca) and magnesium (Mg) m;iy precipitate on the mem¬branes and cause damage on the membranes. Ca and Mg may also form sparingly soluble salts which are eLogging the compart¬ments of the cell, thus leading to an interruption in the production due to restoration of: t; he ce.ii.3.
Several methods have been proposed to overcome the problem with chloride and potassium build-up in pulping chemical recovery systems. One - -ixanip J e is evaporation .of cooking liquid to recrystallize sodium chloride and potassium chloride. Also known is leaching of. precipitator dust and discarding the leach liquid rich in chloride.
According to Tran et al, Pulp Paper Canada 91(5) : T185-T190 (1990), the easiest and most effective way to control chloride, as well as potassium, in the chemical recovery cycle today, is by directly discarding the precipitator dust. Therefore, still the most commonly used method is removal of part of the precipitator dust from the system, and subsequent deposition on land or discharge to water. However, this will not only be environmentally unacceptable, but also result in a loss of valuable cooking chemicals.
US-A-5,352,332 discloses a process for recycling bleach plant filtrate. Precipitator dust: i.s ollected and treated by leaching with water or by evaporation crystallization from a water solution. The thus formed .salt; solution is discharged to sewer or recovered for its chlorine value.
WO-A1-9404747 discloses a process, in which the content of chloride in a recovery system for pulping chemicals can be reduced. The process comprises collecting precipitator dust, dissolving the dust in water to produce an aqueous solution of precipitator dust, whereupon said aqueous solution is elec¬trolysed in a cell for production of chlorine or hydrochloric acid in the anolyte.
JP-A-55022051 discloses a process for reduction of chloride where precipitator dust is washed with a Glauber's salt solution, whereafter a part of the washing solution is treated by electrodialysis to remove chloride.

CA 1059271 discloses a process lot reduction of chloride in a {Mil}) mill reenv.-ry ::y: :l . -m . I' 1 i with hot water at a temperature oi: 60-100°C. Chloride is precipitated from the leached solution by cooling crystalliza¬tion. Solid sulphate is recycled to the black liquor'. Acid (sulphuric acid) is added in the; leaching to lower the pH in order to precipitate sulphate.
The present invention nd it.es to ,i process by which the content of chloride, potassium and oilier moi.ii i'wis in ,1 recovery system for pulping chemicala can be reduced. The process comprises bringing spent liquor to a recovery boiler, burning said spent liquor optionally together with make-up chemicals, collecting precipitator dust formed, leaching the precipitator dust with a leaching liquid at a temperature exceeding 50°C, for a residence time sufficient to form a chloride and potassium enriched leach solution and to remove at least, a part of the content u, whereupon said leach solution is electrochemically treited, preferably in an electrodialysis cell in order to remove at least a part of the chloride and potassium therein.
By the present process, the problem of sticky deposits in the recovery boiler can be substantially reduced. This means an improved energy efficiency :.s well as a higher degree of recovery of the pulping chemicals.
Another advantage of the present, process is the possi¬bility to reduce the content of potassium in the liquid inventory and more particular!" in the spent liquor entering the recovery boiler.
A further advantage is the reduction of metal ions in the recirculation liquid, which is important when using electrolysis in the treatment of waste liquids.
The process is energy efficient, has low investment costs and offers a possibility to remove chloride, potassium and metal ions, with a minimum loss of valuable substances like sodium and sulphate. In the electrochemical embodiment, the cells can be operated at very high current densities,

which result in low investment cost for cells and membranes.
By the present process, chloride may be removed from the precipitator dust by leaching with a saturated,, or near saturated aqueous sulphate solution. Similar result might be possible to reach by leaching with water, but with higher loss of precipitator dust.
Potassium and sodium are alkali metals present in the spent liquors.
The present invention can be used in the production of a chemical pulp and especially for production of a sulphate pulp, soda pulp or sulphite pulp with JII alkali metal as base. A kraft pulp is a special type of sulphate pulp, where the pulp is under-cooked to produce a dark-coloured pulp of exceptional strength. The present: invention can also be used in the production of sulphate, scda or sulphite pulps with an alkali metal as base, where the cooking processes have been modified, combined or extended compared to the normal pulping techniques. Suitably, the p>J A liquid inventory is the total quantity of various liquids in a mill, with varying contents of active or activat-uble cooking liquid component::. Tin • liquid inventory of a sulphate mill, mainly consists ot white liquor, black liquor, green liquor and spent liquor entering the recovery boiler. The spent liquor to be burned in the present process, is a used cooking liquid withdrawn from a digester, optionally with added make-up chemicals.
The amount of precipitator dust: formed depends mainly on the temperature in the boiler, the ratio between sodium and sulphur in the spent liquor and the i iw material and sulphid ity of the cooking process. A high temperature in the lower part of the boiler to reduce the suit net content in the flow gases, increases the amount of dust for-red.
With the present process a l I e:: a portion of the precipitator dust collected and withdrawn from the recovery system is leached with a leaching liquid and treated electro-

chemically. The proportion between t)i amount of dust: electro-chemically treated and recycled iireot ly to the flow of spent liquor, can be chosen with respect to the initial content of chloride and potassium ions in the dust. The composition of precipitator dust formed in recovery boilers vary considerably depending on type and origin of wood, cooking process, purity of make-up chemicals, tempoiature in the boiler, type of precipitator etc. However, i. LM '.ipect 1 ve of these factors the dust mainly consists of sodium and potassium salts, where sulphate, carbonate and chloride ar= the dominant anions. A typical composition of precipitator dust from a kraft recovery system is Na2SO, 80-85% by weight, Na2C03 2-8% by weight, NaCl 2-8% by weight, NaHS04 + Na2S,Ov The leaching should be performed at a temperature exceeding 5 0°C, in order to reach a maximum amount of potas¬sium chloride in the leach solvit ion and a minimum amount in the separated solid phase. Below SO0'-:' the. content of potassium chloride in the leach solution will be poor, and most of the potassium will remain in tlu :.o.l id phase, which is unfavourable. The upper temperature IO" limited, by practical reasons. There is generally no advantages of performing the leaching above 100°C. The leachiug in preferably performed in the range from above 50°C up to about 90°C, suitable from about 60°C up to about 80°C, and moot preferably from about 65°C up to about 75°C.
The residence time of the leaching is preferably at least about 1 minute. The uppei residence time is not criti-cal, but have to be set by process technical reasons. However, any improved leaching results have not been observed exceeding about 1080 minutes. The residence time is preferably in the range from about 5 minutes up to about 1080 minutes, suitably from about 5 minutes up to about 180 minutes.
The chloride and potassium enriched leach solution is separated from the solid phase of the leached precipitator dust, by e.g. filtration, centri Eugaf. ion, sedimentation etc.. The leach solution can be filtered before the electrochemical

treatment to remove undissolve!.!, precipitated or flocculated compounds. By this preferred filtering, especially the content of calcium is reduced, but also the content of phosphate, aluminium and silicon are reduced to a considerable extent. In filtering the solution, mainly flocculated organic compounds and precipitated inorganic compounds are removed. The filter can be of any conventional type, e.g. a drum, belt or table filter with or without vacuum being applied.
According to a preferred embodiment, the separated solid phase can be further treated, e.g. by filtering and addition of water, in order to get a second solid phase comprising mainly of metal compounds, metal i.on:?., organics, sodium sulphate and carbonate. The filtrate, mainly water, separated from the second solid phase may be recirculated to the leaching step. The thus formed second solid phase can be further treated in order to produce acid and alkali, and to separate compounds of silicon, phocph ate, metal ions and other harmful compounds for the pro., ems. The thus separated com¬pounds can be deposited, reey Inorganic. or flocculated organic impurities, are suitably precipitated ami :: The pH in the leaching st::p can be in the range from about 6 up to abcuc 14, suitably fr-in .h >nt 7 up to about 12 and preferably from about 10 up to about 12. The pH can be adjusted by adding sodium hydroxide Be Low a pH about 6, CO-, will be formed, inter alia from the -carbonate.
The added leaching liquid ma/ 'Comprise of water, or

wctucx BuiuLions or suipnace or curDcnatt;. Added sulphate may


electrochemical treatment.
The electrochemical treatment is preferably carried out by electrodialysis by transferring the chloride ions over an anion selective membrane by applying an electrical current perpendicular to the membrane surface. Dissolved cations are transferred in the opposite direction over a cation selective membrane. A large number of alternating anion and cation selective membrane can be arranged in a stack between an anode and a cathode to give diluate and concentrate chambers. The treatment in the cell gives a salt: solution with chloride as the dominant anion and a precipitator dust solution which is depleted with respect to chloride. The electrochemical treatment is preferably performed in a stack with anion selective membranes which are more selective for monovalent anions, e.g. chloride, compared, to divalent anions, e.g. sulphate.
The pH is preferably adjusted before the leach solution reaches the electrochemical t v Preferably the desalination is performed by electrodialysis of the resulting salt solution, normally essentially or entirely consisting of: inorganic materials, to form a diluate with reduced salt: concentration and a first electrodialysis concentrate of the salts in solution. The diluate, mainly comprising sodium sulphate, can be at least partly recycled to the leaching ;;tep The diluate may also be recycled to other places in the pulp mill. The first electrodialysis concentrate of teed Leach solution mainly comprising harmless inorganic salts like sodium chloride and potassium chloride, can be sewerel to: the sea. It is, however, oossible to recover the inorganic s::eiv. 3, especially if there are mainly chloride-containing su 1.'.::;, and purify these further, e.g. to produce acid and alkali, or for use in a plant for the production of sodium cluorate aimed for bleach¬ing. In this case the pulp mill in.ay be closed in a very broad sense.

It is possible to obtain a 3 M chloride solution with only about 0,1 to about 0,3 M sulphate, by an electrodialys treatment with a current efficiency for chloride removal between 80-90%. The concentrate may comprise from about 5 up to about 200 g/1 sodium chloride and from about 0,5 g/1 sulphate up to saturation.
Part or all of the chloride depleted solution can also be electrochemically treated in a membrane cell to give acid and caustic which can be used as internal supply for adjust¬ment of pH in the mill.
The electrodes used in the electrochemical treatment, can be of the conventional type. The anode and the cathode may be made of the same material. The material of the cathode may be steel or nickel, suitably nickel, graphite, titanium, coated titanium or activated nickel. Suitable anodes are made of lead, graphite, titanium, coated titanium, lead oxides, tin oxide, tantalum or titanium, or combinations thereof.
The temperature in the cells should preferably not exceed 50°C since the membranes can be damaged at temperatures beyond 50°C. But the membranes in the future may withstand temperatures exceeding 50°C. Thus, the limit is not critical but set of technical reasons.
The current density may be in the range from about 0,2 up to about 10 kA/m2, suitably in the range from 0,5 up to 5 kA/m2 and preferably in the range from 1 up to 3 kA/m2.
The current efficiency for removal of chloride should be maintained above about 50%. The current efficiency is suitably maintained in the range from about 55 up to about 100% and preferably in the range from about 65 up to about i nnsr

Accordingly the present invention provides a process for reducing the content of chloride, potassium and other metal ions in a recovery system for pulping chemicals by bringing spent liquor to a recovery boiler, burning said spent liquor, collecting precipitator dust formed characterized in that the precipitator dust is leached with a leaching liquid at a temperature exceeding 50°C and at a pH above 6 to form a solid phase comprising metals and organic material and a chloride and potassium enriched leach solution and said phase is separated from the chloride and potassium enriched leach solution, whereupon said leach solution is subjected to an electrochemical treatment for removing at least a part of the chloride and potassium therein.
The present invention will now be described in more detail with reference to embodiments given by way of example and shown in the accompanying drawings, in which;
Figure 1 shows a schematic description of an electrochemical plant where chloride and potassium are removed from precipitator dust.
Figure 2 shows an example of a flow-chart of an electrodialysis cell.
Figure 1 shows roughly a process where dust (1), formed in a recovery boiler and collected in a dry-bottom electrostatic precipitator, is brought to a leaching step (2). A

solid phase (3) is separated from a chloride, potassium and sulphate enriched leach solution (4). The leach solution is preferably further brought to an electrodialysis cell (5) . The electrodialysis treatment result in a chloride and potassium enriched solution (6) which is separated and preferably brought to further treatment. The chloride and potassium depleted solution (7), enriched on inter alia sodium sulphate, may be recirculated to the leach i.ng step (2). The separated solid phase (3) in the leaching, may be subjected to a treatment (8), e.g. by filtration, in order to form a second solid phase (9) comprising metals, carbonate, sulphate and organics. Additional water (10) may also be added in the treatment step (8) . The liquid (11) , mainly water, can be recirculated to the leaching st>:p (2) . In the leaching step additional carbonate may be add"d ( 1 2) . Carbonate may also be added to the dust (1) or to the recycled solution (7) .
Figure 2 shows, in a preferred embodiment, an electrodialysis cell comprising at least one anion selective (MA) and one cation selective (C) membrane between an anode and a cathode. Normally the cell comprises multiple pairs of alternating anion selective and cation selective membranes between one anode and one cathode. The electrodialysis treatment is preferably per retailed in a stack with anion selective membranes which are more selective for monovalent anions (MA), e.g. chloride, compared to divalent anions, e.g. sulphate. Pairs of membranes form between them compartments with inlets and outlets for feeding liquids to and withdrawing liquids from said compartment:::. Ai the anode, an anode-solution (30) is added and at tin: cathode, a cathode-solution (31) is added. When the leach <.ei.ut.mi is fed into the cell monovalent anions e.g. chloride will migrate through monoanion selective: memorane towards> y
anode and the cations, e.g. pot. :e-;si.. v r. i and sodium ions, will migrate through the cation selective membrane (C) towards the cathode. The water solution will be depleted in salt, i.e. diluate (33) . The chloride enriched concentrate (34) may be prepared in every other compartment.. The diluate can be recycled at least partially to ehe leaching step or to other places in the pulp mill. The diluate can also be subjected to

one or more desalination treatments, preferably to one or more electrodialysis treatments (35) for further reduction of the salt content therein. It is preferred to operate the elec¬trodialysis stacks at a high current density to minimize the size and the investment cost. Electrodialysis can be performed in electrodialysis stacks operat: inq in parallel and/or in series, and with liquid stream I: low in parallel and/or in series.
The obtained diluate can be further desalinated in additional electrodialysis stacks operating at lower current densities to obtain a higher deqree of desalination before a preferred recycle to the leaching step, the evaporator or other liquors in the pulp mill.
The part of the diluate that is not recycled to the leaching can be desalinated in .1 :: •' j ■. 11 .11 The concentrate (34) is suitably formed in every second chamber of the electrodialysis cell and to the chambers are added concentrated solution (32) . The compartments may contain only chloride and harmless inorganic salts in concentrations from about 5 up to about 200 grams per litre and may be sewered, e.g. to the sea. It is, hownvei;, possible to recover the inorganic salts, which may l>e mainly chloride-containing salts, and purify these further for u;je e.g. in a plant for production of sodium chlorate foi: bleaching. In this case the pulp mill may be closed in a very broad sense. In case heavy metals or other metals harmful to t:he pulping process are present in the bleach effluent, t.hes;- may be separated in the electrochemical stage and collected in the concentrate stream, where they may be removed by conveni..Lond.l brine purification processes, many of which are well-know e.g. from patents be¬longing to this applicant and others.
The conversion' in the cells ahould preferably exceed about 50%.
The invention and its advantages are illustrated in more detail by the following examples which, however, are only intended to illustrate the invention and not to limit the

same. The percentages and part used in the description, claims and examples, refer to percentage by weight and parts by weight, unless otherwise specified. Example 1
80 g of a precipitator dust, having a carbonate content of 6% by weight, was dissolved in 120 ml saturated sodium sulphate solution, with a content of .1.7 g/1 sodium chloride solution. The temperature was '15°C during the leaching. The slurry was stirred for 5 minute.a and thereafter the solution was filtered. Tests have been made at pll o, 10 and 12. At each pH-value tests have been made without any addition of extra carbonate, and with an addition of 4% by weight solid phase carbonate.




Example 2
80 g of a precipitator dust: having a carbonate content of 0% by weight, was dissolved Ln 120 ml saturated sodium sulphate solution, with a content ot 17 g/1 sodium chloride solution (pH 10). The temperature was 65°C during the leach-ing. The slurry was stirred for 5 minutes and thereafter the solution was filtered. At each pH-value tests have been made without any addition of extra carbonate, and with an addition of 2, 6 and 10 % by weight, solid sodium carbonate. When carbonate and dust were added, the pH increased as evident from Table III. In test 5 no carbonate was added, but instead the pH was raised to 12 by addition of alkali.
Table III

As evident from the Table, a substantial reduction of calcium can be made by adding carbonate. The reduction of calcium is dependent on the carbonate addition, not on the pH. Example 3
A test with electrodialysJ.S ol precipitator dust have been made in a lab cell equipped with monoanion and cation selective membranes. The initial coi : eutrations of chloride, potassium and the current density in i he diluate solution have been varied according to Table IV, Tl>. cell, with an electrode area of 1,72 dm3, was equipped wi.th i en. membrane pairs. The anion selective membranes were nemo, u e..<: selective membranes of type neosepta asv and the eaiion i .active were cmv platinum v i. e. one on each side>
the ten membrane pairs, were used to measure the membrane voltage. Samples of the brine and diluate were taken every half hour and an analyses of chloride, sulphate sodium and potassium ion concentrations were don-- . The initial concentra¬tion of sodium chloride in the bi me .solution was about 0,5 M. The electrode rinse solution was SO i/j sodium sulphate. The results are evident from Table IV.
Table LV
Test Current CI" [%] K' [%.] Current Current
density eff.%Cl" eff. %K*
[kA/m2] +/-10% +/-5%
10 1 1,5 8,7 4,0 90 2 0
2 0,3 2,9 .,!,8 93 2 0
3 2,5 9,7 2,2 100 ,10
As evident from Table IV chloride and potassium can be sufficiently removed over a wide range and with relatively 15 high current efficiency.


WE CLAIM:
1. A process for reducing the content of chloride, potassium and other metal ions in a recovery system for pulping chemicals by bringing spent liquor to a recovery boiler, burning said spent liquor, collecting precipitator dust formed characterized in that the precipitator dust (1) is leached (2) with a leaching liquid at a temperature exceeding 50°C and at a pH above 6 to form a solid phase (3) comprising metals and organic material and a chloride and potassium enriched leach solution and said phase (3) is separated from the chloride and potassium enriched leach solution (4), whereupon said leach solution is subjected to an electrochemical treatment (5) for removing at least a part of the chloride and potassium therein.
2. The process according to claim 1, wherein the pulping chemicals comprises sulphur.
3. The process according to claim 1, wherein the pH at leaching is in the range of from about 7 up to 12.
4. The process according to claim 1, wherein the temp at leaching is in the range of from 60°C to 80°C.
5. The process according to claim 1, wherein the leaching liquid (7) comprises sodium sulphate, depleted of chloride, recycled from the electro chemical step (5).

6. The process according to claim 1, the cell is an electrodialysis
cell (5).
7. The process according to claim 6, wherein the electrodialysis
cell (5) comprises cation (C) and monoanion (MA) selective membranes.
8. The process according to claims 1, 6 or 7, wherein the sodium
chloride and potassium chloride is produced in the electrochemical cell (5).
9. The process according to claim 1, wherein carbonate is added
(12) in the leaching step, to the precipitator dust or to the recycled leaching
liquid.
10. The process according to claim 1, wherein the solid phase is
subjected to a further treatment by adding water and filtering for producing a
second solid phase.
11. A process for reducing the content of chloride, potassium and
other metal ions in a recovery system for pulping chemicals substantially as
herein described with reference to the accompanying drawing.


Documents:

1204-mas-1996 abstract.pdf

1204-mas-1996 claims.pdf

1204-mas-1996 correspondence -others.pdf

1204-mas-1996 correspondence -po.pdf

1204-mas-1996 description (complete).pdf

1204-mas-1996 drawings.pdf

1204-mas-1996 form-2.pdf

1204-mas-1996 form-26.pdf

1204-mas-1996 form-4.pdf

1204-mas-1996 form-6.pdf

1204-mas-1996 petition.pdf


Patent Number 194877
Indian Patent Application Number 1204/MAS/1996
PG Journal Number 08/2007
Publication Date 23-Feb-2007
Grant Date 19-Dec-2005
Date of Filing 09-Jul-1996
Name of Patentee M/S. EKA CHEMICALS AB
Applicant Address S-445 80, BOHUS
Inventors:
# Inventor's Name Inventor's Address
1 JOHN LANDFORS NORRA JARNVAGSGATAN 10, S- 840 10 LJUNGAVERK,
2 KIMONA HAGGSTROM GNEJSVAGEN 28, S-853- 57 SUNDSVALL
3 ROY HAMMER- OLSEN SATURNUSVAGEN 4, S-854 68 SUNDSVALL,
PCT International Classification Number N/A
PCT International Application Number N/A
PCT International Filing date
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 9502583.9 1995-07-12 Sweden