CA1200074A - Process for production of metal calcines of low sulfur content - Google Patents
Process for production of metal calcines of low sulfur contentInfo
- Publication number
- CA1200074A CA1200074A CA000416832A CA416832A CA1200074A CA 1200074 A CA1200074 A CA 1200074A CA 000416832 A CA000416832 A CA 000416832A CA 416832 A CA416832 A CA 416832A CA 1200074 A CA1200074 A CA 1200074A
- Authority
- CA
- Canada
- Prior art keywords
- concentrate
- mineral
- calcine
- fluid bed
- copper
- 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
Links
Classifications
-
- 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
- C22B1/00—Preliminary treatment of ores or scrap
- C22B1/02—Roasting processes
- C22B1/10—Roasting processes in fluidised form
Landscapes
- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Manufacturing & Machinery (AREA)
- Geochemistry & Mineralogy (AREA)
- Geology (AREA)
- General Life Sciences & Earth Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- Environmental & Geological Engineering (AREA)
- Materials Engineering (AREA)
- Mechanical Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Manufacture And Refinement Of Metals (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
The present invention contemplates fluidizing mineral concentrates with excess oxidizing gas in a fluid bed reactor while providing a reducing environment above the fluid bed, for example, by introducing a carbonaceous reductant above the bed so that the total amount of SO3 present is effectively reduced thereby minimizing recombination of sulfur with the calcine concentrate.
The present invention contemplates fluidizing mineral concentrates with excess oxidizing gas in a fluid bed reactor while providing a reducing environment above the fluid bed, for example, by introducing a carbonaceous reductant above the bed so that the total amount of SO3 present is effectively reduced thereby minimizing recombination of sulfur with the calcine concentrate.
Description
~00074 .
1 This invention is concerned with improvements in
1 This invention is concerned with improvements in
2 sulfide mineral roasting processes. More particularly,
3 the instant invention is concerned with the fluid bed dead
4 roasting of sulfide mineral concentrates, particularly chalcopyrite and sphalerite concentrates.
6 The dead roasting of sulfide mineral concen-7 trates, such as sphalerite or chalcopyrite concentrates in ~ a fluid bed roasting process, offers the potential of g producing a calcine which contains relatively low amounts of sulfur, for example, less than about 1 percent sulfur.
11 Experience has shown, however, that the actual sulfur 12 levels in fluid bed roasted calcines are typically of the 13 order of 2 to 3 percent. The higher levels of sulfur 14 measured in fluid bed roasted calcines are due primarily to the sulfation of the calcine entrained in the hot 16 roaster gases and carried over into the particulate 17 recovery systems, such as the cyclones and/or electro-18 static precipitators. This sulfation occurs at the 19 lower temperatures present in the waste heat boiler or the particulate recovery systems by the reaction of metal 21 oxide in the calcine with sulfur trioxide in the gas such 22 as is shown in equation (1) below in connection with 23 copper oxide.
24 CuO + S03 ~ Cu~04 (1) .
The sulfur trioxide is generated by the reaction 26 of sulfur dioxide generated during the roasting with 27 excess oxygen present in the roaster gas (equation 2).
28 S02 + 1/2 2 ~ so3 (2) 29 Thus, althouyh excess oxygen is desirable during roasting to ensure complete elimination of the sulfur from the 31 mineral concentrate, the presence of excess oxygen in the 2 recovery system is undesirable because it results in the 33 generation of sulfur trioxide, which in turn increases the 34 sulfur content of the calcine.
.1~000~
1 In accordance with the present invention, a 2 process for preparing metal calcines having relatively low 3 sulfur contents, for example, sulfur contents below about 4 1 percent, is provided. Simply stated, the present invention contemplates fluidizing mineral concentrates, 6 especially mineral concentrates containing metals selected 7 from copper, zinc and nickel, in an ascending oxidizing 8 gas, said gas containing sufficient oxygen or other g oxidizing agent to ensure substantially complete oxidation of the mineral concentrate while providing a reducing 11 environment above the fluid bed so that the total amount 12 of SO3 present is effectively reduced thereby preventing 13 recombination of sulfur with the calcined concentrate.
14 In one embodiment of the present invention, the reducing gas is provided over the fluid bed by introduc-16 tion of a carbonaceous reductant, such as pulverized coal, 17 natural gas, methane, propane, oil, hydrogen and the like 18 in the fluid bed reactor above the bed of fluidized 19 mineral concentrate.
Referring now to the Figure which is a schematic 21 diagram illustrating the use of a fluid bed reactor in the 22 practice of the present invention, there is shown a 23 vertical reactor 10 of the type employed in fluidizing 24 and roasting mineral concentrates such as copper, zinc and nickel concentrates. The reactor 10 is provided with a 26 conduit 11 for the introduction of mineral concentrate 27 into the reactor. Also, a conduit 12 is provided for 28 the introduct.ion of an oxidizing gas for fluidizing and 29 roasting the mineral concentrate. The reactor 10 is equipped with a grid 14 that distributes the ascending 31 oxidizing gas used to fluidize the particulate mineral 32 concentrate~ solids above the grid. In the Figure, the 33 fluidized bed of mineral concentrate solids is shown 34 generally as reference numeral 15. As can be seen, the reactor is also provided with a conduit 16 for removal 36 of the roasted calcine and a conduit 17 for providing a 37 reducing gas in reactor 10 above the fluid bed 15.
38 The effluent from reactor 10 is passed by a ~.~
. .
lZOO~
1 conduit 18 to a gas-solid separator, such as a cyclone 2 19 in which entrained solids are separated and removed 3 from the offgases. The solids are removed from the 4 cyclone via line 20, and the offgases exit from the top of the cyclone and are sent via line 21 for SO2 recovery.
6 Optionally, but preferably, the effluent from reactor 10 7 is passed through a waste heat boiler (not shown) prior to 8 being passed to the gas solid separator 19.
g In the practice of the present invention, sulfide containing mineral concentrates are employed 11 containing metals selected from copper, zinc and nickel.
12 Typically, these mineral concentrates are obtained by 13 crushing and grinding sulfide ores which are subsequently 14 processed in a concentration mill to produce a concen-lS trated, finely divided material composed principally of 16 metal sulfides and iron sulfides. Indeed, in the practice 17 of the present invention, copper concentrates such as 1~ chalcopyrite and bornite concentrates are particularly 19 preferred. Although particular reference is made herein-after to processing of copper concentrates, it should be 21 understood that other mineral concentrates such as zinc 22 and nickel concentrates may be employed in the practice of 23 the present invention. For example, the zinc concentrate 24 sphalerite ~nay be employed in the process of the present invention.
26 Returning now to the practice of the present 27 invention in general, copper concentrates, useful herein, 28 will contain from about 20 to about 32 percent copper, 29 and they will have fluidizable particle sizes ranging generally froln about 10 ~m to 250 ~m in diameter.
31 ~s indicated above, the copper concentrate 32 is fed into reactor 10 via line 11 where it is fluidized 33 by the ascending oxidizing gas fed into reactor 10 via 34 line 12. Thus, the mineral concentrate is first roasted under oxidizing conditions to oxidize the sulfur, iron and 36 copper present, the copper preferably to cupric oxide 37 (CuO) and the iron to hematite (Fe2o3). In general, 38 roasting is carried out at temperatures below the melting 12Q()0~7~
1 point of the minerals in order to prevent the sticking and 2 bogging of the fluid bed; however, the temperature must 3 be sufficiently high to promote the conversion of the 4 copper sulfides and iron sulfides present in the ore to their respective copper and iron oxides in a reasonably 6 efficient manner. Thus, it is particularly preferred to 7 conduct the roasting at temperatures generally in the 8 range of about 850C to about 1050C, and preferably 9 in the range of about 900C to about 1000C.
~s can be readily appreciated, the oxidizing gas 11 introduced into the reactor to fluidize the ore can be 12 oxygen or air; however, since air is more economical, it 13 is the preferred material for fluidizing and roasting the 14 ore concentrate.
The amount of air that is employed is sufficient 16 to provide an excess of oxygen necessary to convert the 17 copper and iron sulfides present in the ore to their 18 respective oxides. Typically, the amount employed is such 19 as to provide about 1.1 times the stoichiometric amount required for the oxidization of the sulfides to their 21 oxides.
22 As is readily appreciated, it is not generally 23 necessary to add heat to carry out the roasting reaction.
24 However, if the heat of combustion of the concentrate is insufficient to sustain an autogenous roasting reaction 26 at the desired temperature, the combustion air may be 27 preheated to temperatures in the range from about 100C
28 to about 500'~C. Thus, the feed material, especially 29 chalcopyrite ore concentrate, is fluidized and roasted in reactor 10 by an excess of ascending oxidizing gas 31 thereby resulting in the presence of sulfur trioxide and 32 oxygen effluent gas stream. In accordance with the 33 present invention, however, a reducing gas such as methane 34 is introduced above the fluid bed 15 in reactor 10 in quantities sufficient to consume all free oxygen 36 present, thereby continuously driving the reaction shown 37 in equation (3) to the right until the system is substan-38 tially free of both oxygen and SO3.
.
6 The dead roasting of sulfide mineral concen-7 trates, such as sphalerite or chalcopyrite concentrates in ~ a fluid bed roasting process, offers the potential of g producing a calcine which contains relatively low amounts of sulfur, for example, less than about 1 percent sulfur.
11 Experience has shown, however, that the actual sulfur 12 levels in fluid bed roasted calcines are typically of the 13 order of 2 to 3 percent. The higher levels of sulfur 14 measured in fluid bed roasted calcines are due primarily to the sulfation of the calcine entrained in the hot 16 roaster gases and carried over into the particulate 17 recovery systems, such as the cyclones and/or electro-18 static precipitators. This sulfation occurs at the 19 lower temperatures present in the waste heat boiler or the particulate recovery systems by the reaction of metal 21 oxide in the calcine with sulfur trioxide in the gas such 22 as is shown in equation (1) below in connection with 23 copper oxide.
24 CuO + S03 ~ Cu~04 (1) .
The sulfur trioxide is generated by the reaction 26 of sulfur dioxide generated during the roasting with 27 excess oxygen present in the roaster gas (equation 2).
28 S02 + 1/2 2 ~ so3 (2) 29 Thus, althouyh excess oxygen is desirable during roasting to ensure complete elimination of the sulfur from the 31 mineral concentrate, the presence of excess oxygen in the 2 recovery system is undesirable because it results in the 33 generation of sulfur trioxide, which in turn increases the 34 sulfur content of the calcine.
.1~000~
1 In accordance with the present invention, a 2 process for preparing metal calcines having relatively low 3 sulfur contents, for example, sulfur contents below about 4 1 percent, is provided. Simply stated, the present invention contemplates fluidizing mineral concentrates, 6 especially mineral concentrates containing metals selected 7 from copper, zinc and nickel, in an ascending oxidizing 8 gas, said gas containing sufficient oxygen or other g oxidizing agent to ensure substantially complete oxidation of the mineral concentrate while providing a reducing 11 environment above the fluid bed so that the total amount 12 of SO3 present is effectively reduced thereby preventing 13 recombination of sulfur with the calcined concentrate.
14 In one embodiment of the present invention, the reducing gas is provided over the fluid bed by introduc-16 tion of a carbonaceous reductant, such as pulverized coal, 17 natural gas, methane, propane, oil, hydrogen and the like 18 in the fluid bed reactor above the bed of fluidized 19 mineral concentrate.
Referring now to the Figure which is a schematic 21 diagram illustrating the use of a fluid bed reactor in the 22 practice of the present invention, there is shown a 23 vertical reactor 10 of the type employed in fluidizing 24 and roasting mineral concentrates such as copper, zinc and nickel concentrates. The reactor 10 is provided with a 26 conduit 11 for the introduction of mineral concentrate 27 into the reactor. Also, a conduit 12 is provided for 28 the introduct.ion of an oxidizing gas for fluidizing and 29 roasting the mineral concentrate. The reactor 10 is equipped with a grid 14 that distributes the ascending 31 oxidizing gas used to fluidize the particulate mineral 32 concentrate~ solids above the grid. In the Figure, the 33 fluidized bed of mineral concentrate solids is shown 34 generally as reference numeral 15. As can be seen, the reactor is also provided with a conduit 16 for removal 36 of the roasted calcine and a conduit 17 for providing a 37 reducing gas in reactor 10 above the fluid bed 15.
38 The effluent from reactor 10 is passed by a ~.~
. .
lZOO~
1 conduit 18 to a gas-solid separator, such as a cyclone 2 19 in which entrained solids are separated and removed 3 from the offgases. The solids are removed from the 4 cyclone via line 20, and the offgases exit from the top of the cyclone and are sent via line 21 for SO2 recovery.
6 Optionally, but preferably, the effluent from reactor 10 7 is passed through a waste heat boiler (not shown) prior to 8 being passed to the gas solid separator 19.
g In the practice of the present invention, sulfide containing mineral concentrates are employed 11 containing metals selected from copper, zinc and nickel.
12 Typically, these mineral concentrates are obtained by 13 crushing and grinding sulfide ores which are subsequently 14 processed in a concentration mill to produce a concen-lS trated, finely divided material composed principally of 16 metal sulfides and iron sulfides. Indeed, in the practice 17 of the present invention, copper concentrates such as 1~ chalcopyrite and bornite concentrates are particularly 19 preferred. Although particular reference is made herein-after to processing of copper concentrates, it should be 21 understood that other mineral concentrates such as zinc 22 and nickel concentrates may be employed in the practice of 23 the present invention. For example, the zinc concentrate 24 sphalerite ~nay be employed in the process of the present invention.
26 Returning now to the practice of the present 27 invention in general, copper concentrates, useful herein, 28 will contain from about 20 to about 32 percent copper, 29 and they will have fluidizable particle sizes ranging generally froln about 10 ~m to 250 ~m in diameter.
31 ~s indicated above, the copper concentrate 32 is fed into reactor 10 via line 11 where it is fluidized 33 by the ascending oxidizing gas fed into reactor 10 via 34 line 12. Thus, the mineral concentrate is first roasted under oxidizing conditions to oxidize the sulfur, iron and 36 copper present, the copper preferably to cupric oxide 37 (CuO) and the iron to hematite (Fe2o3). In general, 38 roasting is carried out at temperatures below the melting 12Q()0~7~
1 point of the minerals in order to prevent the sticking and 2 bogging of the fluid bed; however, the temperature must 3 be sufficiently high to promote the conversion of the 4 copper sulfides and iron sulfides present in the ore to their respective copper and iron oxides in a reasonably 6 efficient manner. Thus, it is particularly preferred to 7 conduct the roasting at temperatures generally in the 8 range of about 850C to about 1050C, and preferably 9 in the range of about 900C to about 1000C.
~s can be readily appreciated, the oxidizing gas 11 introduced into the reactor to fluidize the ore can be 12 oxygen or air; however, since air is more economical, it 13 is the preferred material for fluidizing and roasting the 14 ore concentrate.
The amount of air that is employed is sufficient 16 to provide an excess of oxygen necessary to convert the 17 copper and iron sulfides present in the ore to their 18 respective oxides. Typically, the amount employed is such 19 as to provide about 1.1 times the stoichiometric amount required for the oxidization of the sulfides to their 21 oxides.
22 As is readily appreciated, it is not generally 23 necessary to add heat to carry out the roasting reaction.
24 However, if the heat of combustion of the concentrate is insufficient to sustain an autogenous roasting reaction 26 at the desired temperature, the combustion air may be 27 preheated to temperatures in the range from about 100C
28 to about 500'~C. Thus, the feed material, especially 29 chalcopyrite ore concentrate, is fluidized and roasted in reactor 10 by an excess of ascending oxidizing gas 31 thereby resulting in the presence of sulfur trioxide and 32 oxygen effluent gas stream. In accordance with the 33 present invention, however, a reducing gas such as methane 34 is introduced above the fluid bed 15 in reactor 10 in quantities sufficient to consume all free oxygen 36 present, thereby continuously driving the reaction shown 37 in equation (3) to the right until the system is substan-38 tially free of both oxygen and SO3.
.
- 5 1 S03 ~ SO2 + 1/2 2 (3) 2 As indicated, the reducing gas may be, but is 3 not restricted to, methane. Thus, for example, introduc-4 tion of coal or oil into the reactor above the fluid bed 15 via line 17 will achieve similar results. The minimum
6 amount of reducing agent required is the sum of quantities
7 A and B,
8 where ~ is the amount of carbon, as carbon g monoxide, methane or the like, necessary to combine with all free oxygen as typified by the reactions shown in 11 equations (4) and (5); and 12 2 + 2 CO -~2CO2 (4) 13 2 2 + CH4 > C2 + 2 H2O (5) 14 where B is an amount of reducing gas equivalent to that required for the direct reduction of SO3 as 16 shown in equation (~).
17 SO3 + CO ` S02 ~ C2 (6) .
18 The concentration of SO3 in the gas stream 19 prior to reduction will vary with temperature, S02 and 2 concentrations; however, virtually all SO3 will be 21 converted to SO2.
22 Excess reductant such as carbon monoxide or 23 hydrogen preC;ent in the effluent gas will reduce copper 24 oxide yresent in the effluent stream in accordance with equation (7) below.
26 CuO + C0~ Cu + C02 (7) 27 Thus, some copper may report in the particulate materials 28 recovered from the gas particle separator 19 in the form 29 of copper metal.
Solids recovered in separator l9 are removed ::
' ~200(~
1 via line 20 and combined, if so desired, with the calcine 2 removed from reactor 10 via line 16. Thereafter, the 3 calcine can be treated in the standard smelting operations 4 or by hydrometallurgical methods for recovery of copper therefrom.
6 Although the present invention has been de-7 scribed in particular detail in connection with copper 8 concentrates, other mineral concentrates may be employed g such as those containing primarily zinc or nic~el.
Also, from the foregoing, it should be apparent 11 that certain modifications and changes can be made in 12 the present invention without departing from the spirit 13 and scope of the invention, and that such modifications 14 and variations are considered to be within the scope of the appended claims.
,, .
17 SO3 + CO ` S02 ~ C2 (6) .
18 The concentration of SO3 in the gas stream 19 prior to reduction will vary with temperature, S02 and 2 concentrations; however, virtually all SO3 will be 21 converted to SO2.
22 Excess reductant such as carbon monoxide or 23 hydrogen preC;ent in the effluent gas will reduce copper 24 oxide yresent in the effluent stream in accordance with equation (7) below.
26 CuO + C0~ Cu + C02 (7) 27 Thus, some copper may report in the particulate materials 28 recovered from the gas particle separator 19 in the form 29 of copper metal.
Solids recovered in separator l9 are removed ::
' ~200(~
1 via line 20 and combined, if so desired, with the calcine 2 removed from reactor 10 via line 16. Thereafter, the 3 calcine can be treated in the standard smelting operations 4 or by hydrometallurgical methods for recovery of copper therefrom.
6 Although the present invention has been de-7 scribed in particular detail in connection with copper 8 concentrates, other mineral concentrates may be employed g such as those containing primarily zinc or nic~el.
Also, from the foregoing, it should be apparent 11 that certain modifications and changes can be made in 12 the present invention without departing from the spirit 13 and scope of the invention, and that such modifications 14 and variations are considered to be within the scope of the appended claims.
,, .
Claims (8)
OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A process for preparing a mineral calcine having a sulfur content below about 1 percent comprising:
providing a mineral concentrate of fluidizable particle sizes;
fluidizing said mineral concentrate in a fluid bed reactor by ascending oxidizing gas, whereby said mineral concen-trate is roasted to a metal oxide containing calcine and an effluent gas stream containing entrained metal oxide containing calcine is obtained;
providing a reducing environment above the fluidized concentrate in amounts sufficient to at least reduce a part of the SO3 present in said effluent gas to SO2 whereby sulfation of the metal oxide in said calcine entrained in the effluent gas is at least partially prevented; and recovering said entrained calcine from said effluent gas stream whereby a mineral calcine having a sulfur content below about 1 percent is obtained.
providing a mineral concentrate of fluidizable particle sizes;
fluidizing said mineral concentrate in a fluid bed reactor by ascending oxidizing gas, whereby said mineral concen-trate is roasted to a metal oxide containing calcine and an effluent gas stream containing entrained metal oxide containing calcine is obtained;
providing a reducing environment above the fluidized concentrate in amounts sufficient to at least reduce a part of the SO3 present in said effluent gas to SO2 whereby sulfation of the metal oxide in said calcine entrained in the effluent gas is at least partially prevented; and recovering said entrained calcine from said effluent gas stream whereby a mineral calcine having a sulfur content below about 1 percent is obtained.
2. The process of claim 1 wherein said mineral concentrate is fluidized by oxidizing gas and roasted at temperatures ranging between about 850°C to about 1050°C.
3. The process of claim 2 wherein said temperatures range between about 900°C and about 1000°C.
4. The process of claim 1 wherein said reducing environment is provided by adding a carbonaceous reductant in the fluid bed reactor above the fluid bed.
5. The process of claim 4 wherein said carbonaceous reductant is selected from pulverized coal, natural gas, methane, propane, oil and hydrogen.
6. The process of claim 5 wherein said oxidizing gas is air in amounts ranging from about 1.1 to 1.6 times the stoichio-metric amount required for oxidation of the sulfides in said concentrate to their oxides and wherein said carbonaceous reductant is methane.
7. The process of any one of claims 1, 2 or 3 wherein said mineral concentrate is selected from the group consisting of copper, zinc and nickel concentrates.
8. The process of claim 6 wherein said concentrate is a copper concentrate selected from chalcopyrite and bornite concentrates.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US34209382A | 1982-01-25 | 1982-01-25 | |
| US342,093 | 1982-01-25 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1200074A true CA1200074A (en) | 1986-02-04 |
Family
ID=23340299
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000416832A Expired CA1200074A (en) | 1982-01-25 | 1982-12-02 | Process for production of metal calcines of low sulfur content |
Country Status (6)
| Country | Link |
|---|---|
| JP (1) | JPS58133327A (en) |
| AU (1) | AU553653B2 (en) |
| BE (1) | BE895684A (en) |
| CA (1) | CA1200074A (en) |
| DE (1) | DE3300609A1 (en) |
| FI (1) | FI71952C (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE102015110772A1 (en) | 2015-07-03 | 2017-01-05 | Outotec (Finland) Oy | Method and plant for roasting dry ore particles in a fluidized bed |
| CN109364734B (en) * | 2018-11-07 | 2021-05-11 | 江西理工大学 | Method for reducing output of waste acid in non-ferrous metal smelting flue gas treatment process |
| CN109364735B (en) * | 2018-11-07 | 2021-05-18 | 江西理工大学 | Method for reducing sulfur trioxide in nonferrous smelting flue gas by using metal sulfide |
-
1982
- 1982-12-02 CA CA000416832A patent/CA1200074A/en not_active Expired
-
1983
- 1983-01-11 DE DE19833300609 patent/DE3300609A1/en not_active Withdrawn
- 1983-01-21 FI FI830216A patent/FI71952C/en not_active IP Right Cessation
- 1983-01-24 AU AU10722/83A patent/AU553653B2/en not_active Ceased
- 1983-01-24 BE BE0/209952A patent/BE895684A/en not_active IP Right Cessation
- 1983-01-25 JP JP1046483A patent/JPS58133327A/en active Pending
Also Published As
| Publication number | Publication date |
|---|---|
| AU553653B2 (en) | 1986-07-24 |
| AU1072283A (en) | 1983-08-04 |
| JPS58133327A (en) | 1983-08-09 |
| FI71952C (en) | 1987-03-09 |
| FI830216A0 (en) | 1983-01-21 |
| DE3300609A1 (en) | 1983-08-04 |
| BE895684A (en) | 1983-07-25 |
| FI830216L (en) | 1983-07-26 |
| FI71952B (en) | 1986-11-28 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |