EP0085728B1 - Improved grinding of titaniferous ores to enhance recovery of titanium dioxide - Google Patents

Improved grinding of titaniferous ores to enhance recovery of titanium dioxide Download PDF

Info

Publication number
EP0085728B1
EP0085728B1 EP19820100910 EP82100910A EP0085728B1 EP 0085728 B1 EP0085728 B1 EP 0085728B1 EP 19820100910 EP19820100910 EP 19820100910 EP 82100910 A EP82100910 A EP 82100910A EP 0085728 B1 EP0085728 B1 EP 0085728B1
Authority
EP
European Patent Office
Prior art keywords
ore
titanium dioxide
titaniferous
recovery
polyol
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
Application number
EP19820100910
Other languages
German (de)
French (fr)
Other versions
EP0085728A1 (en
Inventor
Gerard Martin Sheehan
Donald Edward Knapp
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Wyeth Holdings LLC
Original Assignee
American Cyanamid Co
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by American Cyanamid Co filed Critical American Cyanamid Co
Priority to EP19820100910 priority Critical patent/EP0085728B1/en
Priority to DE8282100910T priority patent/DE3271092D1/en
Publication of EP0085728A1 publication Critical patent/EP0085728A1/en
Application granted granted Critical
Publication of EP0085728B1 publication Critical patent/EP0085728B1/en
Expired legal-status Critical Current

Links

Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B02—CRUSHING, PULVERISING, OR DISINTEGRATING; PREPARATORY TREATMENT OF GRAIN FOR MILLING
    • B02C—CRUSHING, PULVERISING, OR DISINTEGRATING IN GENERAL; MILLING GRAIN
    • B02C23/00—Auxiliary methods or auxiliary devices or accessories specially adapted for crushing or disintegrating not provided for in preceding groups or not specially adapted to apparatus covered by a single preceding group
    • B02C23/06—Selection or use of additives to aid disintegrating
    • 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
    • C22B34/00—Obtaining refractory metals
    • C22B34/10—Obtaining titanium, zirconium or hafnium
    • C22B34/12—Obtaining titanium or titanium compounds from ores or scrap by metallurgical processing; preparation of titanium compounds from other titanium compounds see C01G23/00 - C01G23/08
    • C22B34/1204—Obtaining titanium or titanium compounds from ores or scrap by metallurgical processing; preparation of titanium compounds from other titanium compounds see C01G23/00 - C01G23/08 preliminary treatment of ores or scrap to eliminate non- titanium constituents, e.g. iron, without attacking the titanium constituent

Definitions

  • This invention relates to a method for improving the grinding of titaniferous ores and increasing the amount of recovery of titanium dioxide from said ores.
  • the first step in the sulfuric acid process for recovery of titanium dioxide from titaniferous ores is to grind the ore to a desired particle size.
  • the ore is digested with sulfuric acid to yield a digestion cake which consists essentially of water-soluble sulfates of titanium and iron, as well as minor impurities.
  • the recovery of titanium can be determined by comparing (a) the titanium assay and weight of the ore to (b) the titanium assay and volume of the resulting solution.
  • the sulfuric acid process for preparing titanium dioxide from titaniferous ores is conducted on a large scale and thus, even a small increase in the recovery of titanium dioxide can be commercially important. For example, for a 25 ton batch of titaniferous ore containing 64.6% titanium dioxide, a change in the titanium dioxide recovery from 84.5% to 89% represents a 29% decrease in unrecovered, or wasted titanium dioxide, and 1400 pounds extra titanium dioxide actually recovered. So, any increase in the efficiency of comminution of a titaniferous ore will result in a worth-while saving even though the unit saving may appear small.
  • Canadian Patent No. 962,003 discloses the application of propane diol to pigmentary titanium dioxide, following its preparation by either of the well known sulfuric acid or chloride processes, to improve the dispersibility characteristics of the pigment, particularly in paints; and U.S. Patent No. 3,076,719 describes a treatment of similarly produced titanium dioxide pigment with a polyol of from 4 to 10 carbon atoms which prevents clumping during storage.
  • U.S. Patent No. 2,822,241 discloses the addition of a glyceride, particularly a monoglyceride, to a titaniferous ore containing organic flotation agents to improve the digestion of the ore in sulfuric acid.
  • the present invention provides as a major object a method whereby the comminution of titaniferous ores may be conducted more efficiently, with the use of certain polyols, so that the recovery of titanium dioxide from said ores upon digestion may be enhanced. Further objects and advantages of the invention will become apparent from the description of the invention which ensues.
  • the polyols used in the method of the present invention have the formula: wherein R is alkyl (C,-C 4 ), or hydroxyalkyl (C,-C 4 ) containing up to 3 hydroxy groups, and wherein R' is alkylene (C,-C 3 ).
  • R is alkyl (C,-C 3 ) and R' is methylene.
  • R is ethyl and R' is methylene.
  • the polyols are preferably stable and wettable in concentrated sulfuric acid at ambient temperatures (25°C, to 35°C.), but tend to be less stable at the digestion reaction temperature.
  • Suitable such compounds include trimethylolpropane, 1-hydroxy-2,2-dimethylolpropane; 1-hydroxy-2,2-dimethylol- pentane; 1-hydroxy-3,3-diethylolpentane; 1,3-dihydroxy-2,2-dimethylolbutane, and pentaerythritol.
  • the polyol is added to the titaniferous ore in an amount effective to improve the comminution thereof. Generally this amount will be from about 0.005% to about 2% by weight of the ore, desirably from about 0.05% to about 1 %, and preferably from about 0.07% to about 0.5%. However, more of the polyol may be added if so desired.
  • the comminution is rendered more efficient and the ultimate recovery of titanium dioxide from the ore, upon digestion thereof in sulfuric acid, is enhanced.
  • the polyol appears to act as an anti-caking agent for the ore during comminution, resulting in a more rapid reduction of ore particle size.
  • the smaller particles are believed to be better wetted by the sulfuric acid, thereby yielding a higher recovery of titanium dioxide.
  • the continued presence of the polyol in the sulfuric acid digestion medium apparently further augments the recovery of titanium dioxide from the ore.
  • TMP trimethylolpropane
  • a typical chemical assay of this Florida ore which is weathered beach sand, reveals hat the titanium dioxide content thereof is 64.6%.
  • a 1500 g. sample of the ore was first dried at 110°C. to less than 0.2% water and then placed in a gallon ball jar containing 7500 g. of 2.54cm (1 inch) steel balls.
  • the ball jar was rotated at 53 rpm for the lengths of time shown in Table I below.
  • the ball jar was emptied and the ore particle size determined on a 100 g. sample by sifting in a.Tyier Ro-Tap through a bank of sieves ranging from 100 to 325 mesh (0.147 to 0.043 mm) (Tyler-U.S. Standard) for 30 minutes.
  • Table 1 demonstrates that for grind times of 30 minutes and 360 minutes, more -325 mesh (0.043 mm) particles were produced when TMP in an amount of 0.1 % was added to the ore. For this procedure, regular commercially used steel balls, which were not polished, were employed..
  • This example shows the improvement in titanium dioxide recovery when a titaniferous ore which was ground using a polyol as a grinding aid is digested with sulfuric acid.
  • the method used in this example closely approximates the industrial digestion process, so the results received here are representative of results which would be expected on an industrial scale.
  • Example 2 four separate 1000 g. samples of the titaniferous ore comminuted for equal times as in Example 1, two samples with, and two samples without, the addition of 0.1 % TMP, were wetted with 98% sulfuric acid for 30 minutes. Each mixture of ore and sulfuric acid was then heated to 115°C. over periods ranging from 19 to 31 minutes, while 60 ml. of water was added to simulate the dilution which occurs in the industrial process when high pressure steam (2.76 bar) (40 psig) is introduced into the mixture. End liquor, i.e., the mother liquor which remains after the titaniferous liquor is hydrolyzed to yield titanium dioxide, was then added to achieve the desired ratio of sulfuric acid to basic oxides in the ore.
  • End liquor i.e., the mother liquor which remains after the titaniferous liquor is hydrolyzed to yield titanium dioxide
  • the end liquor contained about 20% sulfuric acid, and a sufficient quantity was added so that after the valences of all other recoverable sulfatable ore components had been satisfied, there remained enough sulfuric acid to satisfy between 65 and 80% of the titanium valences with sulfate ions.
  • the samples were digested in the acid solution at temperatures of about 180 ⁇ 190°C. for about 2 1/2 hours. Thereupon, the resulting digestion cakes were dissolved in water to form a titaniferous liquor which was analyzed for titanium dioxide content, and the results compared with the analysis of the original ore, to determine the titanium dioxide recovery.
  • the determination of recovery can be made using any well known method, e.g., reduction of the titanium (IV) to titanium (III) with zinc amalgam and titration of the reduced titanium with ferric ammonium sulfate to a thiocyanate end-point.
  • Example 1 The procedure of Example 1 is repeated, except that the trimethylolpropane is replaced by an equal weight amount of 1-hydroxy-2,2-dimethylolpropane; 1-hydroxy-2,2-dimethylolpentane; 1-hydroxy-3,3-di- ethylolpentane; 1,3-dihydroxy-2,2-dimethylolbutane, and pentaerythritol.
  • Example 1 The procedure of Example 1 is repeated, except that trimethylolpropane in amounts equal to 0.005%, 0.05%, 0.5%, 1% and 2% is added to the ore.

Landscapes

  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Environmental & Geological Engineering (AREA)
  • General Life Sciences & Earth Sciences (AREA)
  • Geology (AREA)
  • Manufacturing & Machinery (AREA)
  • Food Science & Technology (AREA)
  • Materials Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Manufacture And Refinement Of Metals (AREA)
  • Inorganic Compounds Of Heavy Metals (AREA)

Description

  • This invention relates to a method for improving the grinding of titaniferous ores and increasing the amount of recovery of titanium dioxide from said ores.
  • The first step in the sulfuric acid process for recovery of titanium dioxide from titaniferous ores, is to grind the ore to a desired particle size. Next the ore is digested with sulfuric acid to yield a digestion cake which consists essentially of water-soluble sulfates of titanium and iron, as well as minor impurities. After dissolution of the digestion cake in either water or dilute sulfuric acid, the recovery of titanium can be determined by comparing (a) the titanium assay and weight of the ore to (b) the titanium assay and volume of the resulting solution.
  • The sulfuric acid process for preparing titanium dioxide from titaniferous ores is conducted on a large scale and thus, even a small increase in the recovery of titanium dioxide can be commercially important. For example, for a 25 ton batch of titaniferous ore containing 64.6% titanium dioxide, a change in the titanium dioxide recovery from 84.5% to 89% represents a 29% decrease in unrecovered, or wasted titanium dioxide, and 1400 pounds extra titanium dioxide actually recovered. So, any increase in the efficiency of comminution of a titaniferous ore will result in a worth-while saving even though the unit saving may appear small.
  • Canadian Patent No. 962,003 discloses the application of propane diol to pigmentary titanium dioxide, following its preparation by either of the well known sulfuric acid or chloride processes, to improve the dispersibility characteristics of the pigment, particularly in paints; and U.S. Patent No. 3,076,719 describes a treatment of similarly produced titanium dioxide pigment with a polyol of from 4 to 10 carbon atoms which prevents clumping during storage.
  • U.S. Patent No. 2,822,241 discloses the addition of a glyceride, particularly a monoglyceride, to a titaniferous ore containing organic flotation agents to improve the digestion of the ore in sulfuric acid.
  • While the prior art discloses use of polyols to improve the qualities of recovered titanium dioxide and the digestion of titaniferous ores, as hereinabove described, the present invention provides as a major object a method whereby the comminution of titaniferous ores may be conducted more efficiently, with the use of certain polyols, so that the recovery of titanium dioxide from said ores upon digestion may be enhanced. Further objects and advantages of the invention will become apparent from the description of the invention which ensues.
  • In accordance with the objects of the present invention, it has been found that certain polyols, when added to an unground titaniferous ore, can increase the efficiency of comminution of the ore.
  • The polyols used in the method of the present invention have the formula:
    Figure imgb0001
    wherein R is alkyl (C,-C4), or hydroxyalkyl (C,-C4) containing up to 3 hydroxy groups, and wherein R' is alkylene (C,-C3). Preferably, R is alkyl (C,-C3) and R' is methylene. Most preferably, R is ethyl and R' is methylene. The polyols are preferably stable and wettable in concentrated sulfuric acid at ambient temperatures (25°C, to 35°C.), but tend to be less stable at the digestion reaction temperature. Suitable such compounds include trimethylolpropane, 1-hydroxy-2,2-dimethylolpropane; 1-hydroxy-2,2-dimethylol- pentane; 1-hydroxy-3,3-diethylolpentane; 1,3-dihydroxy-2,2-dimethylolbutane, and pentaerythritol.
  • The polyol is added to the titaniferous ore in an amount effective to improve the comminution thereof. Generally this amount will be from about 0.005% to about 2% by weight of the ore, desirably from about 0.05% to about 1 %, and preferably from about 0.07% to about 0.5%. However, more of the polyol may be added if so desired.
  • By the introduction of the polyol to the ore either prior to or during comminution, the comminution is rendered more efficient and the ultimate recovery of titanium dioxide from the ore, upon digestion thereof in sulfuric acid, is enhanced. The polyol appears to act as an anti-caking agent for the ore during comminution, resulting in a more rapid reduction of ore particle size. The smaller particles, in turn, are believed to be better wetted by the sulfuric acid, thereby yielding a higher recovery of titanium dioxide.
  • In addition to enhancing the comminution of the titaniferous ore, the continued presence of the polyol in the sulfuric acid digestion medium apparently further augments the recovery of titanium dioxide from the ore.
  • The following examples are provided for illustrative purposes and may include particular features of the invention. However, the examples should not be construed as limiting the invention, many variations of which are possible without departing from the spirit or scope thereof. All parts and percentages are by weight unless otherwise noted.
    • Example 1
  • In this example, the effectiveness of trimethylolpropane (TMP), corresponding to the above polyol formula wherein R is ethyl and R' is methylene, as a grinding aid in the size reduction of a Florida ore from a deposit in Green Cove Springs is shown.
  • A typical chemical assay of this Florida ore, which is weathered beach sand, reveals hat the titanium dioxide content thereof is 64.6%.
  • A 1500 g. sample of the ore was first dried at 110°C. to less than 0.2% water and then placed in a gallon ball jar containing 7500 g. of 2.54cm (1 inch) steel balls. The ball jar was rotated at 53 rpm for the lengths of time shown in Table I below. At the conclusion of the selected grind times, the ball jar was emptied and the ore particle size determined on a 100 g. sample by sifting in a.Tyier Ro-Tap through a bank of sieves ranging from 100 to 325 mesh (0.147 to 0.043 mm) (Tyler-U.S. Standard) for 30 minutes.
  • Table 1 demonstrates that for grind times of 30 minutes and 360 minutes, more -325 mesh (0.043 mm) particles were produced when TMP in an amount of 0.1 % was added to the ore. For this procedure, regular commercially used steel balls, which were not polished, were employed..
    Figure imgb0002
    • Example 2
  • This example shows the improvement in titanium dioxide recovery when a titaniferous ore which was ground using a polyol as a grinding aid is digested with sulfuric acid.
  • The method used in this example closely approximates the industrial digestion process, so the results received here are representative of results which would be expected on an industrial scale.
  • Specifically, four separate 1000 g. samples of the titaniferous ore comminuted for equal times as in Example 1, two samples with, and two samples without, the addition of 0.1 % TMP, were wetted with 98% sulfuric acid for 30 minutes. Each mixture of ore and sulfuric acid was then heated to 115°C. over periods ranging from 19 to 31 minutes, while 60 ml. of water was added to simulate the dilution which occurs in the industrial process when high pressure steam (2.76 bar) (40 psig) is introduced into the mixture. End liquor, i.e., the mother liquor which remains after the titaniferous liquor is hydrolyzed to yield titanium dioxide, was then added to achieve the desired ratio of sulfuric acid to basic oxides in the ore. The end liquor contained about 20% sulfuric acid, and a sufficient quantity was added so that after the valences of all other recoverable sulfatable ore components had been satisfied, there remained enough sulfuric acid to satisfy between 65 and 80% of the titanium valences with sulfate ions. The samples were digested in the acid solution at temperatures of about 180―190°C. for about 2 1/2 hours. Thereupon, the resulting digestion cakes were dissolved in water to form a titaniferous liquor which was analyzed for titanium dioxide content, and the results compared with the analysis of the original ore, to determine the titanium dioxide recovery. The determination of recovery can be made using any well known method, e.g., reduction of the titanium (IV) to titanium (III) with zinc amalgam and titration of the reduced titanium with ferric ammonium sulfate to a thiocyanate end-point.
  • It was found upon analysis that the average recovery of titanium dioxide from the two samples which had been comminuted with trimethylolpropane was 86.5%. For the two samples comminuted without the use of trimethylolpropane, the average recovery was only 80%.
    • Example 3
  • The procedure of Example 1 is repeated, except that the trimethylolpropane is replaced by an equal weight amount of 1-hydroxy-2,2-dimethylolpropane; 1-hydroxy-2,2-dimethylolpentane; 1-hydroxy-3,3-di- ethylolpentane; 1,3-dihydroxy-2,2-dimethylolbutane, and pentaerythritol.
  • Similar improved comminution of the ore is observed.
    • Example 4
  • The procedure of Example 1 is repeated, except that trimethylolpropane in amounts equal to 0.005%, 0.05%, 0.5%, 1% and 2% is added to the ore.
  • Similar improved comminution of the ore is observed.

Claims (5)

1. A method for improving the comminution of a titaniferous ore which comprises adding to said ore a polyol having the formula:
Figure imgb0003
wherein R is alkyl (C1―C4) or hydroxyalkyl (C1―C4) containing up to three hydroxy groups and wherein R' is alkylene (C1―C3), in an amount effective to reduce the particle size of the ore as a result of the comminution.
2. The method of Claim 1 wherein R of the formula R―C(̵R'OH)3 is alkyl (C1―C4) and R' of said formula is. methylene.
3. The method of Claim 1 wherein the polyol is trimethylolpropane.
4. The method of Claim 1 wherein the polyol is present in an amount equal to from about 0.005% to about 2% by weight of the ore.
5. The method of Claim 1 wherein the polyol is present in an amount equal to from about 0.05% to about 1% by weight of the ore.
EP19820100910 1982-02-09 1982-02-09 Improved grinding of titaniferous ores to enhance recovery of titanium dioxide Expired EP0085728B1 (en)

Priority Applications (2)

Application Number Priority Date Filing Date Title
EP19820100910 EP0085728B1 (en) 1982-02-09 1982-02-09 Improved grinding of titaniferous ores to enhance recovery of titanium dioxide
DE8282100910T DE3271092D1 (en) 1982-02-09 1982-02-09 Improved grinding of titaniferous ores to enhance recovery of titanium dioxide

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
EP19820100910 EP0085728B1 (en) 1982-02-09 1982-02-09 Improved grinding of titaniferous ores to enhance recovery of titanium dioxide

Publications (2)

Publication Number Publication Date
EP0085728A1 EP0085728A1 (en) 1983-08-17
EP0085728B1 true EP0085728B1 (en) 1986-05-14

Family

ID=8188863

Family Applications (1)

Application Number Title Priority Date Filing Date
EP19820100910 Expired EP0085728B1 (en) 1982-02-09 1982-02-09 Improved grinding of titaniferous ores to enhance recovery of titanium dioxide

Country Status (2)

Country Link
EP (1) EP0085728B1 (en)
DE (1) DE3271092D1 (en)

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CA1243646A (en) * 1984-12-04 1988-10-25 William K. Kodatsky Method for treating carbide-based desulfurizing reagents for injection into molten iron
EP0840105A1 (en) * 1996-11-05 1998-05-06 Orbisphere Laboratories Neuchatel Sa Spectroscopic method and apparatus

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2822241A (en) * 1953-08-17 1958-02-04 Nat Lead Co Digestion in sulphuric acid of titaniferous ore concentrates containing organic flotation agent
NL259274A (en) * 1960-09-15
US3549091A (en) * 1968-03-14 1970-12-22 Nat Lead Co Fluid energy milling tio2 pigment
US3758322A (en) * 1971-07-21 1973-09-11 American Cyanamid Co Rutile tio2 slurries

Also Published As

Publication number Publication date
EP0085728A1 (en) 1983-08-17
DE3271092D1 (en) 1986-06-19

Similar Documents

Publication Publication Date Title
CN1064086C (en) Method for recovering valuable elements from rare-earth and ferrous alloy
US3784670A (en) Titanium dixide concentrate and its manufacturing process
CN109402415A (en) A kind of preparation of low grade natural rutile can chlorination rich-titanium material method
US4489043A (en) Manufacture of manganous sulfate solutions
US5023059A (en) Recovery of metal values and hydrofluoric acid from tantalum and columbium waste sludge
JPH07509279A (en) Treatment of titanium-containing substances
CN108118166A (en) A kind of technique for being separated from Rare Earth Mine and extracting fluorine carbon cerium mischmetal
US4976939A (en) Processing of rare earth ores
EP0085728B1 (en) Improved grinding of titaniferous ores to enhance recovery of titanium dioxide
US4321152A (en) Grinding of titaniferous ores to enhance recovery of titanium dioxide
US6451273B2 (en) Method of producing an active mineral liquid from granite
JPS6236970B2 (en)
CA1061571A (en) Cuprion process start-up control
EP0420525A2 (en) Recycling metal containing compositions
US4910000A (en) Method of extracting tungsten values from tungsten containing ores
US3939249A (en) Purification of talc
US2812237A (en) Preparation of alkali metal fluotitanates
US4361542A (en) Zircon retrieval
CA1168204A (en) Grinding of titaniferous ores to enhance recovery of titanium dioxide
US3003867A (en) Process for recovery of niobium
JPS6260833A (en) Treatment of rare earth metal ore
JPS5924731B2 (en) Method for removing and recovering uranium or/and thorium from a liquid containing uranium or/and thorium
RU2168556C1 (en) Method of processing loparit concentrate
US4562049A (en) Recovery of titanium from perovskite by acid sulfation
CA2025151A1 (en) Processing of ores containing rare-earth elements

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): BE DE FR GB IT NL

17P Request for examination filed

Effective date: 19831020

GRAA (expected) grant

Free format text: ORIGINAL CODE: 0009210

AK Designated contracting states

Kind code of ref document: B1

Designated state(s): BE DE FR GB IT NL

REF Corresponds to:

Ref document number: 3271092

Country of ref document: DE

Date of ref document: 19860619

ET Fr: translation filed
ITF It: translation for a ep patent filed

Owner name: MODIANO & ASSOCIATI S.R.L.

PLBE No opposition filed within time limit

Free format text: ORIGINAL CODE: 0009261

STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: NO OPPOSITION FILED WITHIN TIME LIMIT

26N No opposition filed
PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: FR

Payment date: 19890106

Year of fee payment: 8

PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: DE

Payment date: 19890110

Year of fee payment: 8

PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: BE

Payment date: 19890116

Year of fee payment: 8

PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: NL

Payment date: 19890228

Year of fee payment: 8

PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: GB

Payment date: 19890531

Year of fee payment: 8

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: GB

Effective date: 19900209

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: BE

Effective date: 19900228

BERE Be: lapsed

Owner name: AMERICAN CYANAMID CY

Effective date: 19900228

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: NL

Effective date: 19900901

GBPC Gb: european patent ceased through non-payment of renewal fee
NLV4 Nl: lapsed or anulled due to non-payment of the annual fee
PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: FR

Effective date: 19901031

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: DE

Effective date: 19901101

REG Reference to a national code

Ref country code: FR

Ref legal event code: ST