US3503857A - Method for producing magnesium ferrosilicon - Google Patents

Method for producing magnesium ferrosilicon Download PDF

Info

Publication number
US3503857A
US3503857A US632971A US3503857DA US3503857A US 3503857 A US3503857 A US 3503857A US 632971 A US632971 A US 632971A US 3503857D A US3503857D A US 3503857DA US 3503857 A US3503857 A US 3503857A
Authority
US
United States
Prior art keywords
magnesium
molten
ferrosilicon
cell
fused salt
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 - Lifetime
Application number
US632971A
Inventor
Robert A Hard
James E Wells
Donald J Hansen
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.)
Elkem Metals Co LP
Original Assignee
Union Carbide Corp
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 Union Carbide Corp filed Critical Union Carbide Corp
Application granted granted Critical
Publication of US3503857A publication Critical patent/US3503857A/en
Assigned to ELKEM METALS COMPANY, A NEW YORK GENERAL PARTNERSHIP reassignment ELKEM METALS COMPANY, A NEW YORK GENERAL PARTNERSHIP ASSIGNMENT OF ASSIGNORS INTEREST. Assignors: UNION CARBIDE CORPORATION, A NY CORP.
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Images

Classifications

    • CCHEMISTRY; METALLURGY
    • C25ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25CPROCESSES FOR THE ELECTROLYTIC PRODUCTION, RECOVERY OR REFINING OF METALS; APPARATUS THEREFOR
    • C25C3/00Electrolytic production, recovery or refining of metals by electrolysis of melts

Definitions

  • This invention relates to the making of magnesiumcontaining ferrosilicon alloys. More particularly, this invention relates to an electrolytic process for incorporating magnesium in ferrosilicon alloys.
  • Magnesium-ferrosilicon is a material widely used in industry for introducing magnesium into molten iron and usually contains from about 3 to magnesium, about 40 to 50% silicon with the balance mostly iron. Very often the magnesium content ranges between about 5 and 10%.
  • magnesium-bearing ferrosilicon alloys have been manufactured by plunging ingots of magnesium metal into molten ferrosilicon (about 50% Si) until the desired magnesium content was obtained.
  • the low boiling point of magnesium (1107 C.) as compared to that of molten ferrosilicon, a substantial amount of magnesium was invariably lost by volatilization which resulted in a significant economic penalty in view of the relatively high cost of magnesium.
  • considerable care must be taken in order to achieve the desired magnesium level in view of the variable loss of magnesium through volatilization.
  • a process in accordance with the present invention comprises providing a molten bath of fused salt which is suitable for use as an electrolyte in the electrolysis of magnesium oxide and providing molten ferrosilicon beneath the molten salt bath and in contact therewith.
  • An electric potential is applied to the molten ferrosilicon whereby it is cathodically energized and an anodically energized electrode is placed in contact with the molten salt bath.
  • Magnesium oxide, in finely divided form, is suspended in the molten salt bath and electrolyzed whereby magnesium metal is liberated, at the molten ferrosilicon cathode, and dissolved therein.
  • magnesium oxide which is relatively inexpensive in both cost and handling, as compared to magnesium metal, is used as the starting material, and there is negligible loss of magnesium.
  • the alumina brick structure 9 serves as an electrically nonconductive vessel for containing molten ferrosilicon shown at 11, upon which a fused salt bath 13 floats due to its lesser density.
  • the molten ferrosilicon is introduced into the cell which contains molten electrolyte and these material are maintained in this condition by the heating effect of the electric current which passes between electrodes 15 and 17 via graphite cell base 18. Supplementary heat can also be employed through the use of auxiliary alternating current heating.
  • the molten ferrosilicon 1'1 is in contact with electrode 17 via base 18 and is thus cathodically energized. Consequently, when ,sufiicient electric potential is applied to the cell 1, magnesium oxide, introduced at 19, and suspended in the fused salt bath 13, is electrolyzed. That is to say, magnesium metal is liberated at the cathodic molten ferrosilicon and dissolves therein thus producing a magnesium-ferrosilicon product. Oxygen is liberated during the electrolysis 'of magnesium oxide, at the anodes 15, which are made of carbon or graphite, and the oxygen combines therewith to form carbon monoxide which exists above the bath. Thus, the liberated oxygen is essentially prevented from reacting with and reoxidizing the liberated magnesium metal.
  • the rate of magnesium production, and hence the magnesium content of the cathodic ferrosilicon product can be readily calculated.
  • the magnesium content can be determined by periodic sampling and when the desired magnesium content is achieved in the molten ferrosilicon, the product can be withdrawn by reduced pressure siphoning, or by means of an exit port (not shown).
  • the composition of the starting molten ferrosilicon material should be at least about 30% Si and can be up to Si. At silicon contents of less than about 30% the amount of magnesium that can be maintained in -the molten alloy is very low and insignificant as a practical matter.
  • the upper limit for the silicon content is determined by the relative density of the molten metal as compared to the fused salt bath electrolyte since it is essential that the molten metal be more dense so that the electrolyte floats above it.
  • the cell operating temperature i.e., the temperature of the molten cell contents
  • the temperature range of about 1250 C. to about 1350 C. since at temperatures below about 1250 C. the magnesium-ferrosilicon product obtained begins to solidify whereas at temperatures above about 1350 C., the vapor pressure of magnesium tends to cause the formation of an unstable alloy product.
  • Control of the current density is also important in the present invention and the anode current density is preferably less than about 10 amperes per square inch in order to avoid polarization. While higher current densities can be used, cell efliciency decreases considerably.
  • Electrolytes i.e., the fused salt baths, used in the present invention should be (a) molten in the temperature range of about 1250 C. to 1350 C. for the reasons previously noted, (b) have a density less than that of the molten ferrosilicon employed and (c) the cation constituents must be less noble than magnesium to avoid their reduction and deposition on the molten ferrosilicon in preference to magnesium.
  • the preferred fused salt bath i.e., electrolyte, is one containing about 70% MgF and about 30% BaF Salts (III) Results:
  • EXAMPLE 1 Using equipment generally similar to that shown in the drawing molten ferrosilicon containing about 50% Si is introduced into the cell which contains a molten mixture of 70% MgF and 30% BaF The ferrosilicon being more dense than the fused salt mixture settles to the bottom of the cell where it contacts the negatively energized graphite bottom element. The molten fused salt floats on top of and covers the molten ferrosilicon and is contacted by vertically positioned graphite electrodes. The electric potential across the cell is adjusted to provide a cathode current density of 4 to 5 amps/in. which maintains the molten state cell of the constituents.
  • magnesium oxide 200 mesh and finer
  • magnesium metal is liberated and dissolves in the molten ferrosilicon at a rate of about 0.35 to 0.43 pound per hour.
  • the oxygen liberated during the electrolysis at the graphite anodes reacts to form carbon monoxide and exitsthe cell.
  • Molten product, i.e., magnesium ferrosilicon is removed from the cell, for example, by siphoning, when the desired magnesium level is reached.
  • EXAMPLE 2 Using a cell unit generally similar to that shown in the drawing having inner cross-section dimensions of about 18" x 27 and using two anodes magnesium ferrosilicon was prepared under the following conditions and with the noted results:
  • magnesium ferrosilicon product obtained was highly suitable for use in the treatment of iron.
  • a method for producing magnesium-containing ferrosilicon alloys which comprises:
  • molten fused salt is a mixture of two or more of the following:

Landscapes

  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Electrolytic Production Of Metals (AREA)

Description

March 31, 1970 R A. HARD- ETAL 3,503,857
METHOD FOR PRODUCING MAGNESIUM FERROSILICON Filed April 24, 1967 INVENTORS ROBERT A. HARD BY D ALD J. HANSEN A ORNEY United States Patent US. Cl. 204-71 Claims ABSTRACT OF THE DISCLOSURE Method for preparing magnesium-containing ferrosilicon by electrolyzing magnesium oxide which is suspended in a fused electrolyte which floats on cathodically energized molten ferrosilicon. Magnesium liberated during electrolysis is attracted to the cathodic molten ferrosilicon and dissolved therein.
This invention relates to the making of magnesiumcontaining ferrosilicon alloys. More particularly, this invention relates to an electrolytic process for incorporating magnesium in ferrosilicon alloys.
Magnesium-ferrosilicon is a material widely used in industry for introducing magnesium into molten iron and usually contains from about 3 to magnesium, about 40 to 50% silicon with the balance mostly iron. Very often the magnesium content ranges between about 5 and 10%. In the past, magnesium-bearing ferrosilicon alloys have been manufactured by plunging ingots of magnesium metal into molten ferrosilicon (about 50% Si) until the desired magnesium content was obtained. On account of the low boiling point of magnesium (1107 C.) as compared to that of molten ferrosilicon, a substantial amount of magnesium was invariably lost by volatilization which resulted in a significant economic penalty in view of the relatively high cost of magnesium. Moreover, considerable care must be taken in order to achieve the desired magnesium level in view of the variable loss of magnesium through volatilization.
It is therefore an object of the present invention to provide a method of making magnesium-containing ferrosilicon alloys whereby loss of magnesium is essentially eliminated.
It is another object of the present invention to provide a method of making magnesium-containing ferrosilicon which avoids the necessity for using magnesium metal as a starting material.
Other objects will be apparent from the following description and claims taken in conjunction with the drawing which shows, somewhat schematically, an electrolytic cell suitable for the practice of the present invention.
A process in accordance with the present invention comprises providing a molten bath of fused salt which is suitable for use as an electrolyte in the electrolysis of magnesium oxide and providing molten ferrosilicon beneath the molten salt bath and in contact therewith. An electric potential is applied to the molten ferrosilicon whereby it is cathodically energized and an anodically energized electrode is placed in contact with the molten salt bath. Magnesium oxide, in finely divided form, is suspended in the molten salt bath and electrolyzed whereby magnesium metal is liberated, at the molten ferrosilicon cathode, and dissolved therein.
Through the use of the foregoing process, magnesium oxide, which is relatively inexpensive in both cost and handling, as compared to magnesium metal, is used as the starting material, and there is negligible loss of magnesium.
The process of the present invention can be more readily understood by reference to the drawing which shows at 1 an electrolytic cell unit having steel shell 3 mounted on supports 5 and surrounding refractory insulation 7.
The alumina brick structure 9, as shown, serves as an electrically nonconductive vessel for containing molten ferrosilicon shown at 11, upon which a fused salt bath 13 floats due to its lesser density. The molten ferrosilicon is introduced into the cell which contains molten electrolyte and these material are maintained in this condition by the heating effect of the electric current which passes between electrodes 15 and 17 via graphite cell base 18. Supplementary heat can also be employed through the use of auxiliary alternating current heating.
As indicated in the drawing, the molten ferrosilicon 1'1 is in contact with electrode 17 via base 18 and is thus cathodically energized. Consequently, when ,sufiicient electric potential is applied to the cell 1, magnesium oxide, introduced at 19, and suspended in the fused salt bath 13, is electrolyzed. That is to say, magnesium metal is liberated at the cathodic molten ferrosilicon and dissolves therein thus producing a magnesium-ferrosilicon product. Oxygen is liberated during the electrolysis 'of magnesium oxide, at the anodes 15, which are made of carbon or graphite, and the oxygen combines therewith to form carbon monoxide which exists above the bath. Thus, the liberated oxygen is essentially prevented from reacting with and reoxidizing the liberated magnesium metal.
As electrolysis continues and magnesium is dissolved in the molten ferrosilicon, additional finely divided magnesium oxide is added to the fused salt bath to replenish that which was electrolytically decomposed. For a given cell of known current efiiciency, the rate of magnesium production, and hence the magnesium content of the cathodic ferrosilicon product can be readily calculated. Alternately, the magnesium content can be determined by periodic sampling and when the desired magnesium content is achieved in the molten ferrosilicon, the product can be withdrawn by reduced pressure siphoning, or by means of an exit port (not shown).
In the practice of the present invention, the composition of the starting molten ferrosilicon material should be at least about 30% Si and can be up to Si. At silicon contents of less than about 30% the amount of magnesium that can be maintained in -the molten alloy is very low and insignificant as a practical matter. The upper limit for the silicon content is determined by the relative density of the molten metal as compared to the fused salt bath electrolyte since it is essential that the molten metal be more dense so that the electrolyte floats above it.
Also, in the present invention, the cell operating temperature, i.e., the temperature of the molten cell contents, should be in the temperature range of about 1250 C. to about 1350 C. since at temperatures below about 1250 C. the magnesium-ferrosilicon product obtained begins to solidify whereas at temperatures above about 1350 C., the vapor pressure of magnesium tends to cause the formation of an unstable alloy product.
Control of the current density is also important in the present invention and the anode current density is preferably less than about 10 amperes per square inch in order to avoid polarization. While higher current densities can be used, cell efliciency decreases considerably.
Electrolytes, i.e., the fused salt baths, used in the present invention should be (a) molten in the temperature range of about 1250 C. to 1350 C. for the reasons previously noted, (b) have a density less than that of the molten ferrosilicon employed and (c) the cation constituents must be less noble than magnesium to avoid their reduction and deposition on the molten ferrosilicon in preference to magnesium.
The preferred fused salt bath, i.e., electrolyte, is one containing about 70% MgF and about 30% BaF Salts (III) Results:
Elapsed time from Percent mg. in start 01 cell operation I Tap No siphoned product (hr.) WhlCh are suitable, singly or in mixture, provided the fore- 7 8 13 going criteria are met, are shown in Table I. 2 11115 19.6 27 17.9 29.25 16.2 35 15.3 36 TABLE I 14.6 37. 5
Material Melting point, O. Specific gravity 1 3 6 EXAMPLE 3 1 38 2:; Using a cell unit generally similar to that shown in the 1,360 drawing having inner cross-section dimensions of about In the practice of the present invention, it has been found that the magnesium oxide starting material should be of a size that it is essentially suspended in the fused salt bath to avoid significant settling. A sizing of 200 mesh and finer (Tyler series) has been found to be suitable.
The following examples will further illustrate the present invention.
EXAMPLE 1 Using equipment generally similar to that shown in the drawing molten ferrosilicon containing about 50% Si is introduced into the cell which contains a molten mixture of 70% MgF and 30% BaF The ferrosilicon being more dense than the fused salt mixture settles to the bottom of the cell where it contacts the negatively energized graphite bottom element. The molten fused salt floats on top of and covers the molten ferrosilicon and is contacted by vertically positioned graphite electrodes. The electric potential across the cell is adjusted to provide a cathode current density of 4 to 5 amps/in. which maintains the molten state cell of the constituents. For a cathode area of 1 square foot the total cell current is on the order of 575 to 720 amperes and to maintain relatively constant operation, magnesium oxide (200 mesh and finer) is added to the fused salt bath at a rate of about 0.58 to 0.72 pounds per hour. Under the foregoing conditions magnesium metal is liberated and dissolves in the molten ferrosilicon at a rate of about 0.35 to 0.43 pound per hour. The oxygen liberated during the electrolysis at the graphite anodes reacts to form carbon monoxide and exitsthe cell. Molten product, i.e., magnesium ferrosilicon, is removed from the cell, for example, by siphoning, when the desired magnesium level is reached.
EXAMPLE 2 Using a cell unit generally similar to that shown in the drawing having inner cross-section dimensions of about 18" x 27 and using two anodes magnesium ferrosilicon was prepared under the following conditions and with the noted results:
(I) Materials:
Anode5% inch diameter graphite Cathode-50%ferrosilicon (100 pounds) Electrolyte MgF (245 pounds)|BaF (105 pounds) (II) Operating conditions:
Molten material temperature1300 C.
Cell currentl500 amperes Cell ampere hours5 3,400
Cathode current density2.6 amps/in.
MgO addition (200 mesh and finer)1.2 pounds per hour (50% C.E.)
18" x 27 and using two anodes magnesium ferrosilicon was prepared under the following conditions and with the noted results:
(I) Materials:
Anode5% inch diameter graphite Cathode50'% ferrosilicon pounds) ElectrolyteMgF pounds)+BaF (60 pounds) (II) Operating conditions:
Molten material temperaturel300 C. Cell current-2000 Cell ampere hours-42,000 Cathode current density3.4 amps/in. Cathode current eificiency60% MgO addition (200' mesh and finer)2 pounds per hour (60% CE.) (III) Results:
Product-magnesium ferrosilicon containing 9.9%
For all examples, there was no noticeable loss of magnesium metal and the magnesium ferrosilicon product obtained was highly suitable for use in the treatment of iron.
What is claimed is:
1. A method for producing magnesium-containing ferrosilicon alloys which comprises:
(1) providing a molten bath of fused salt suitable for use as an electrolyte in the electrolysis of magnesium oxide,
(2) providing molten ferrosilicon beneath the molten salt bath and in contact therewith,.the density of the molten salt bath being less than that of the molten ferrosilicon,
(3) applying an electric potential to the molten ferrosilicon whereby it is cathodically energized,
(4) contacting the molten salt bath with an anodically energized electrode,
(5) suspending finely divided magnesium oxide in the molten salt bath, and
(6) causing an electric current to flow between the anodically energized electrode and the cathodically energized molten ferrosilicon :sufficient to reduce said magnesium oxide whereby magnesium metal is liberated and deposited on the molten ferrosilicon and dissolved therein.
2. A method in accordance with claim 1 wherein the molten fused salt is a mixture of two or more of the following:
3. A method in accordance with claim 1 wherein the molten fused salt bath is a mixture containing about 70% MgF and about 30% BaF 4. A method in accordance with claim 1 wherein the 1,564,139 112/ 1925 Saklatwalla 20471 temperature of the molten fused salt and molten ferro- 3,022,233 2/1962 Olstowski 204-71 XR silicon is in the range of about 1250 C. to about1350 C. 3,024,177 3/ 1962 Cook 2047-1 XR 5. A method in accordance with claim '1 wherein the 3,093,558 6/1963 Labounsky 204--70 molten ferrosilicon contains between about 30% and 90% i 5 JOHN H. MACK, Primary Examiner References Cited D. R. VALENTINE, Assistant Examiner UNITED STATES PATENTS Us cl XR 880,489 2/1908 Kugelgen et a1. 204 70 204 64 1,310,449 7/1919 Seward 204-71XR 10
US632971A 1967-04-24 1967-04-24 Method for producing magnesium ferrosilicon Expired - Lifetime US3503857A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US63297167A 1967-04-24 1967-04-24

Publications (1)

Publication Number Publication Date
US3503857A true US3503857A (en) 1970-03-31

Family

ID=24537750

Family Applications (1)

Application Number Title Priority Date Filing Date
US632971A Expired - Lifetime US3503857A (en) 1967-04-24 1967-04-24 Method for producing magnesium ferrosilicon

Country Status (1)

Country Link
US (1) US3503857A (en)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2362499A1 (en) * 1976-08-18 1978-03-17 Rockwell International Corp NEGATIVE ELECTRODE FOR ELECTRIC ACCUMULATOR AND ITS CONSTRUCTION PROCESS
US4298437A (en) * 1980-01-25 1981-11-03 Occidental Research Corporation Method for producing magnesium metal from molten salt
US5024737A (en) * 1989-06-09 1991-06-18 The Dow Chemical Company Process for producing a reactive metal-magnesium alloy
WO2021090546A1 (en) * 2019-11-07 2021-05-14 三菱重工業株式会社 Electrolytic smelting furnace and electrolytic smelting method

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US880489A (en) * 1905-06-09 1908-02-25 Virginia Lab Company Process of producing magnesium.
US1310449A (en) * 1919-07-22 Electbodeposition of magnesium
US1564139A (en) * 1924-04-08 1925-12-01 Byramji D Saklatwalla Manufacture of alloy steels and irons
US3022233A (en) * 1959-11-18 1962-02-20 Dow Chemical Co Preparation of silicon
US3024177A (en) * 1959-08-04 1962-03-06 Gen Electric Corrosion resistant coating
US3093558A (en) * 1960-08-02 1963-06-11 Univ Lab Inc Production of magnesium from silicates

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1310449A (en) * 1919-07-22 Electbodeposition of magnesium
US880489A (en) * 1905-06-09 1908-02-25 Virginia Lab Company Process of producing magnesium.
US1564139A (en) * 1924-04-08 1925-12-01 Byramji D Saklatwalla Manufacture of alloy steels and irons
US3024177A (en) * 1959-08-04 1962-03-06 Gen Electric Corrosion resistant coating
US3022233A (en) * 1959-11-18 1962-02-20 Dow Chemical Co Preparation of silicon
US3093558A (en) * 1960-08-02 1963-06-11 Univ Lab Inc Production of magnesium from silicates

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2362499A1 (en) * 1976-08-18 1978-03-17 Rockwell International Corp NEGATIVE ELECTRODE FOR ELECTRIC ACCUMULATOR AND ITS CONSTRUCTION PROCESS
US4298437A (en) * 1980-01-25 1981-11-03 Occidental Research Corporation Method for producing magnesium metal from molten salt
US5024737A (en) * 1989-06-09 1991-06-18 The Dow Chemical Company Process for producing a reactive metal-magnesium alloy
WO2021090546A1 (en) * 2019-11-07 2021-05-14 三菱重工業株式会社 Electrolytic smelting furnace and electrolytic smelting method
JP2021075751A (en) * 2019-11-07 2021-05-20 三菱重工業株式会社 Electrolytic refining furnace, and electrolytic refining method

Similar Documents

Publication Publication Date Title
US5024737A (en) Process for producing a reactive metal-magnesium alloy
US5006209A (en) Electrolytic reduction of alumina
US4865701A (en) Electrolytic reduction of alumina
US5254232A (en) Apparatus for the electrolytic production of metals
US3729397A (en) Method for the recovery of rare earth metal alloys
KR101684813B1 (en) Electrolysis tank used for aluminum electrolysis and electrolysis process using the electrolyzer
US3114685A (en) Electrolytic production of titanium metal
US3219561A (en) Dual cell refining of silicon and germanium
US2302604A (en) Fused bath electrolytic production of ferrochromium
US3725222A (en) Production of aluminum
CA1224746A (en) Cell for the refining of aluminum
US2848397A (en) Electrolytic production of metallic titanium
US3335076A (en) Process for purifying and transporting light metal
US2908619A (en) Production of titanium
US4192724A (en) Method for electrolyzing molten metal chlorides
US3503857A (en) Method for producing magnesium ferrosilicon
US3226311A (en) Process of producing calcium by electrolysis
US3464900A (en) Production of aluminum and aluminum alloys from aluminum chloride
US5810993A (en) Electrolytic production of neodymium without perfluorinated carbon compounds on the offgases
US3729398A (en) Process and cell for the electrolytic recovery of aluminum
US4135994A (en) Process for electrolytically producing aluminum
US2939823A (en) Electrorefining metallic titanium
US3508908A (en) Production of aluminum and aluminum alloys
US2431723A (en) Electrolytic method for producing magnesium alloys
NL8002381A (en) ELECTROLYTIC CELL.

Legal Events

Date Code Title Description
AS Assignment

Owner name: ELKEM METALS COMPANY, A NEW YORK GENERAL PARTNERSH

Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:UNION CARBIDE CORPORATION, A NY CORP.;REEL/FRAME:003882/0761

Effective date: 19810626

Owner name: ELKEM METALS COMPANY, 270 PARK AVENUE, NEW YORK, N

Free format text: ASSIGNMENT OF ASSIGNORS INTEREST.;ASSIGNOR:UNION CARBIDE CORPORATION, A NY CORP.;REEL/FRAME:003882/0761

Effective date: 19810626