EP0075836A2 - Verfahren zur Gewinnung von Magnesium - Google Patents

Verfahren zur Gewinnung von Magnesium Download PDF

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Publication number
EP0075836A2
EP0075836A2 EP82108713A EP82108713A EP0075836A2 EP 0075836 A2 EP0075836 A2 EP 0075836A2 EP 82108713 A EP82108713 A EP 82108713A EP 82108713 A EP82108713 A EP 82108713A EP 0075836 A2 EP0075836 A2 EP 0075836A2
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EP
European Patent Office
Prior art keywords
magnesium
composition
temperature
vaporous
carbon monoxide
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.)
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Application number
EP82108713A
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English (en)
French (fr)
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EP0075836A3 (de
Inventor
Julian M. Avery
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Individual
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Individual
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Publication date
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Publication of EP0075836A2 publication Critical patent/EP0075836A2/de
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    • 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
    • C22B26/00—Obtaining alkali, alkaline earth metals or magnesium
    • C22B26/20—Obtaining alkaline earth metals or magnesium
    • C22B26/22—Obtaining magnesium

Definitions

  • This invention relates to a carbothermic process for producing magnesium from magnesium oxide. More particularly, the present invention provides means for greatly decreasing the back- oxidation of magnesium vapor by carbon monoxide as the furnace gases are cooled, which has heretofore prevented successful commercial development of a carbothermic magnesium process.
  • magnesium from magnesium oxide by reduction with carbon in an arc furnace is theoretically the most efficient and cheapest method for the commercial production of magnesium.
  • a reducing agent such as silicon or aluminum requires an expensive preliminary operation requiring electric energy.
  • the magnesia-containing raw material is subjected to high temperature reduction by carbon in an arc furnace.
  • the product initially produced comprises a vaporous composition which is theoretically approximately a 50-50 mixture of magnesium vapor and carbon monoxide gas.
  • thermodynamic calculations for the reaction show that the theoretical reaction equilibrium temperature at atmospheric pressure is about 1875 0 C and in order to carry out the reaction at a reasonable rate, it has been found necessary to operate at temperatures on the order of 2000°C. This thermodynamic constraint is undesirable since it causes extreme difficulty in cooling the furnace gases down to the equilibrium temperature of almost 1875°C, rapidly enough to prevent excessive back oxidation of magnesium by reaction with carbon monoxide to form magnesium oxide.
  • the reaction in question which is reversible as shown, reaches equilibrium at about 1875 0 C at atmospheric pressure of the C0, proceeds violently toward oxidation of magnesium if the gaseous mixture of Mg and CO is cooled below that temperature and above 1875 0 C to the operating temperature of about 2000°C, the reaction proceeds rapidly to the right to effect substantially complete reduction of the magnesium oxide to form magnesium vapor and carbon monoxide.
  • the present invention provides a process for cooling a vaporous product containing carbon monoxide and vaporous magnesium down to a temperature where there is little or no reaction of the magnesium with carbon monoxide.
  • the present invention provides a means for cooling vaporous magnesium sufficiently rapidly as to allow the use of carbothermic process wherein the magnesium vapor is produced from a magnesia-containing feed and a carbonaceous reducing agent in the presence of an electric arc generated by electrodes.
  • the means for cooling the vaporous magnesium comprises liquid magnesium having a temperature close to the vaporization temperature of magnesium in sufficient amounts as to cool the vaporous magnesium down to the magnesium vaporization temperature of about 1100°C substantially instantaneously.
  • This means of cooling can be supplemented by introducing inert gas in admixture with the vapor containing vaporous magnesium chloride or magnesium chloride flux compositions free of oxides. Furthermore, this method can be supplemented by a second cooling step following cooling with liquid magnesium whereby a flux for magnesium is sprayed into the vaporous magnesium for intimate contact therewith.
  • the process of this invention utilizes a furnace 10 having electrodes 12 which extends into the reaction bed 14 which is comprised mainly of magnesium oxide and a carbonaceous reducing material such as coke.
  • the magnesium oxide and coke are introduced into the furnace 10 by means of conduit 16 which also is provided with means for closing the conduit to the atmosphere during reaction.
  • the reaction bed 14 rests on hearth 18.
  • electric arcs are generated between the electrodes 12 in order to effect reaction between magnesium oxide and the carbon to form magnesium vapor and carbon monoxide.
  • the vaporous composition comprising magnesium and carbon monoxide rises towards the top of the furnace and exits therefrom through opening 20.
  • the vaporous composition At the entrance 20, the vaporous composition is a temperature between about 2200°C and about 1900°C. Thus, the temperature of the vaporous composition is within a sufficiently elevated range such that there is little or no back reaction between the vaporous magnesium and the carbon monoxide.
  • the magnesium-carbon monoxide vaporous composition Before the magnesium-carbon monoxide vaporous composition is cooled to a temperature below about 1900°C, it is contacted with molten-magnesium chloride which is heated to a temperature between about 1100°C and 1400°C, preferably between about 1200 0 C and about 1400°C in heater 22 and thereafter is introduced into opening 20 for intimate contact therein with the vaporous composition.
  • contact of the vaporous magnesium can be made with a liquid magnesium chloride flux composition containing an alkali metal chloride but free of oxides haven a temperature near its boiling point, i.e., within about 200°C of its boiling point.
  • the use of the magnesium chloride flux has the advantage of lowering the temperature of the vaporous magnesium further than with pure magnesium chloride in the shock cooling step, but has the disadvantage of requiring additional separation steps to recover pure magnesium.
  • Typical flux compositions comprise KCL (60 wt %), MgCl 2 (40 wt %) or MgCl 2 (50 wt %), KC1 (30 wt %) and NaCl (20 wt %).
  • the liquid magnesium is introduced as a spray.Furthermore, the liquid magnesium chloride or flux composition is introduced under conditions such that substantially all of the liquid magnesium chloride or flux composition is vaporized while minimizing the temperature to which the vaporized magnesium chloride or flux composition is subsequently heated by the vaporous composition of magnesium and carbon monoxide.
  • cooling was effected with liquid magnesium chloride or magnesium in a relatively cooled condition, e.g., 650°C to 670°C.
  • the amount of heat extracted from the vaporous composition of magnesium and carbon monoxide is substantially equal to the heat of vaporization of the introduced liquid magnesium chloride or flux composition rather than relying solely upon reduction by trnsfer of sensible heat from the vaporous composition to the liquid magnesium chloride or flux composition.
  • the vaporous composition removed from the furnace 10 is reduced in temperature to about the magnesium dew point, i.e., below about 1500°C, preferalby below about 1100°C and more preferably between about 1050°C and 1150 0 C substantially instantaneously.
  • the present invention provides a procedure wherein the temperature of the liquid magnesium is reduced from a high temperature range within which substantially no back reaction between carbon monoxide and magnesium is effected to a substantially lower temperature range wherein little or no back reaction of magnesium vapor occurs.
  • the magnesium having a temperature within this lower temperature range then can be cooled at a slower rate utilizing transfer of sensible heat so as to condense and recover the magnesium.
  • the vaporous composition resulting from the initial cooling step is passed from opening 20through conduit 24 into scrubbing tower 26.
  • the vaporous composition comprising magnesium and carbon monoxide is contacted with a molten flux composition for magnesium such as a conventional magnesium chloride composition.
  • Flux #1 has a melting point below 400°C and high fluidity.
  • the flux composition is utilized to separate impurities such as unreacted magnesium oxide from the magnesium.
  • Product gas rich in carbon monoxide and containing little or no magnesium is removed from scrubbing tower 26 through conduit 29.
  • the flux compositions shown in Table I also can be utilized in the initial shock cooling step.
  • molten flux enters scrubbing tower 26 through conduit 28 and 30 and from there passed into conduit 32 which is provided with a plurality of spray nozzles.
  • the molten flux has a temperature of usually between about 400°C and 500°C in order to effect further temperature reduction of the vaporous magnesium so that it is condensed to form a liquid.
  • the liquid magnesium and molten flux pass downwardly through the scrubbing tower 26 to contact baffle 32 from which the liquid flows into container 36.
  • container 36 the liquid magnesium separates into a top strata 38 floating on a bottom strata 40 which comprises the flux.
  • Typical equilization temperatures within container 36 for the magnesium and the molten flux is between about 700°C and 750°C.
  • the liquid magnesium is drawn out through conduit 42 for further processing such as in a foundry 44 to form magnesium ingots.
  • the molten flux 40 is drawn off through conduit 46 to heat exchanger 48 so that the flux can be cooled to a desired temperature and passed through conduit 50 and conduits 28 and 30 for further use for contact with the vaporous magnesium.
  • the flux is cooled such as by conventional heat exchange with water which enters heat exchanger 48 through conduit 52 and leaves heat exchanger 48 as steam through conduit 54.
  • the process of this invention is shown schematically without the use of a scrubbing tower.
  • the process utilizes reactor 10 which is provided with the electrodes 12.
  • the coke and magnesium oxide reactants are introduced into reactor 10 through opening 16 to form a reaction bed 14.
  • the reaction bed 14 rests upon hearth 18.
  • electical power is supplied to the electrodes 12 to cause arcing between them.
  • the vaporous reaction product comprising magnesium and carbon monoxide rises from the reaction bed 14 and exits the reactor 10 through opening 60.
  • the vaporous composition exiting the reactor 10 has a temperature between about 1900 0 C and about 2200°C, i.e., a temperature range wherein little or no back reaction of the carbon monoxide and magnesium occurs.
  • This vaporous composition is contacted with molten magnesium chloride or flux composition which enters the opening 60 through conduit 62 at a temperature near its vaporization temperature as explained above prior to permitting the vaporous reaction composition to cool within a temperature range of which substantial back reaction.of magnesium and carbon monoxide occurs.
  • the contact of the vaporous reaction composition and the molten magnesium chloride or flux composition effects a temperature reduction of the vaporous composition to about the magnesium dew point, i.e., below about 1100°C.
  • the resultant vaporous composition containing magnesium and carbon monoxide enters spray chamber 64 within which it is contacted with a spray of molten flux which has the effect of scavenging impurities from the magnesium product and effects condensation of the magnesium vapor to magnesium liquid.
  • the magnesium liquid forms a floating layer 77 on the liquid flux 68.
  • the temperature of the liquid flux and liquid magnesium is between about 700°C and 750°C.
  • the uncondensed carbon monoxide is removed from chamber 64 through conduit 70 for further use as desired such as a fuel.
  • the liquid magnesium is removed from the magnesium layer 66 through conduit 72 for further processing such as to form ingots in a foundry 74.
  • the molten flux 68 is directed to heat exchanger 76 by means of conduit 78 wherein it is cooled to a temperature between about 400°C and 700°C for recycle by means of conduit 80 to spray chamber 64.
  • Any conventional heat exchanger 76 can be utilized, for example, one utilizing cool water entering through conduit 82 and from which steam is removed.

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Geology (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • General Life Sciences & Earth Sciences (AREA)
  • Manufacturing & Machinery (AREA)
  • Environmental & Geological Engineering (AREA)
  • Materials Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Treating Waste Gases (AREA)
  • Carbon And Carbon Compounds (AREA)
  • Manufacture And Refinement Of Metals (AREA)
EP82108713A 1981-09-21 1982-09-21 Verfahren zur Gewinnung von Magnesium Withdrawn EP0075836A3 (de)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
US30401081A 1981-09-21 1981-09-21
US304010 1981-09-21
BR8302355A BR8302355A (pt) 1981-09-21 1983-05-06 Processo para a recuperacao de magnesio

Publications (2)

Publication Number Publication Date
EP0075836A2 true EP0075836A2 (de) 1983-04-06
EP0075836A3 EP0075836A3 (de) 1985-08-14

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ID=40912825

Family Applications (1)

Application Number Title Priority Date Filing Date
EP82108713A Withdrawn EP0075836A3 (de) 1981-09-21 1982-09-21 Verfahren zur Gewinnung von Magnesium

Country Status (4)

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EP (1) EP0075836A3 (de)
JP (1) JPS58126938A (de)
AU (1) AU8857782A (de)
BR (1) BR8302355A (de)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1994011539A1 (en) * 1992-11-16 1994-05-26 Mineral Development International A/S A method of producing metallic magnesium, magnesium oxide or a refractory material
CN113604680A (zh) * 2021-08-06 2021-11-05 山西中城天朗环保工程有限公司 一种镁合金熔剂渣回收设备及其回收工艺
CN114250366A (zh) * 2019-09-10 2022-03-29 山西宝盛远华新材料股份有限公司 一种利用沸点差别回收镁精炼熔剂废渣的方法及设备

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2051913A (en) * 1933-10-28 1936-08-25 Magnesium Dev Corp Production of magnesium
GB479842A (en) * 1936-08-07 1938-02-07 Nat Processes Ltd Improvements in or relating to the preparation of magnesium
US2381405A (en) * 1942-01-28 1945-08-07 Dow Chemical Co Recovery of magnesium
US2381403A (en) * 1942-01-29 1945-08-07 Dow Chemical Co Recovery of magnesium from vapor mixtures
DE2542595A1 (de) * 1975-09-24 1977-04-07 Halomet Ag Verfahren zur trennung eines gasfoermigen gemisches
US4200264A (en) * 1976-08-16 1980-04-29 Fumio Hori Apparatus for obtaining Mg and Ca through carbon reduction
US4290804A (en) * 1980-02-26 1981-09-22 Avery Julian M Method for producing magnesium

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2051913A (en) * 1933-10-28 1936-08-25 Magnesium Dev Corp Production of magnesium
GB479842A (en) * 1936-08-07 1938-02-07 Nat Processes Ltd Improvements in or relating to the preparation of magnesium
US2381405A (en) * 1942-01-28 1945-08-07 Dow Chemical Co Recovery of magnesium
US2381403A (en) * 1942-01-29 1945-08-07 Dow Chemical Co Recovery of magnesium from vapor mixtures
DE2542595A1 (de) * 1975-09-24 1977-04-07 Halomet Ag Verfahren zur trennung eines gasfoermigen gemisches
US4200264A (en) * 1976-08-16 1980-04-29 Fumio Hori Apparatus for obtaining Mg and Ca through carbon reduction
US4290804A (en) * 1980-02-26 1981-09-22 Avery Julian M Method for producing magnesium

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1994011539A1 (en) * 1992-11-16 1994-05-26 Mineral Development International A/S A method of producing metallic magnesium, magnesium oxide or a refractory material
AU680403B2 (en) * 1992-11-16 1997-07-31 Mineral Development International A/S A method of producing metallic magnesium, magnesium oxide or a refractory material
RU2109078C1 (ru) * 1992-11-16 1998-04-20 Минерал Дивелопмент Интернешнл А/С Способ получения металлического магния, способ получения чистого оксида магния (варианты) и способ переработки исходного материала
CN114250366A (zh) * 2019-09-10 2022-03-29 山西宝盛远华新材料股份有限公司 一种利用沸点差别回收镁精炼熔剂废渣的方法及设备
CN113604680A (zh) * 2021-08-06 2021-11-05 山西中城天朗环保工程有限公司 一种镁合金熔剂渣回收设备及其回收工艺

Also Published As

Publication number Publication date
EP0075836A3 (de) 1985-08-14
AU8857782A (en) 1983-03-31
JPS58126938A (ja) 1983-07-28
BR8302355A (pt) 1984-12-11

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