SE531428C2

SE531428C2 - Metallurgical process for the production of magnesium

Info

Publication number: SE531428C2
Application number: SE0702250A
Authority: SE
Inventors: Guozhu Ye; Eric Burstroem; Nils-Olov Lindfors; Johan Eriksson
Original assignee: Mefos Metallurg Res I Ab
Priority date: 2007-10-09
Filing date: 2007-10-09
Publication date: 2009-03-31
Also published as: SE0702250L; WO2009048363A1

Description

531 423 2 tillsammans. Den brända dolomiten kommer från en kalcineringsugn 12 där dolomiten bränns till CaO~MgO,(kalcineras) och FeAl kommer från en elugn 13 som exempelvis kan vara en DC-ugn eller en ferrolegeringsugn såsom en schaktugn för CaCz produktion. Denna ugn 13 chargeras med antracit (kol) och slagg från ugnen 11. Den slaggen består av CaO, AlzOg samt rest MgO och FeAl (exempelvis 5 vikt% Al). Den FeAl som tappas från ugnen 13 och granuleras innan den chargeras ugnen l 1. Kalciumkarbid bildas i ugnen 13 och avtappas. Restmagnesium i slaggen från ugnen ll forångas i ugnen 13 tillsammans med CO och leds genom en avgaskanal 14 med en kylare 15 och ett elektroﬁlter 16. Mg och CO i avgaserna reagerar vid kylning tillbaka till MgO och C som uppsamlas i elektroﬁltret som fasta ämnen. Den uppsamlade blandningen av magnesiumoxid och kol blandas med dolomiten som chargeras kalcinationsugnen. Kvar blir CO som tas tillvara från avgaskanalen och kan användas som bränsle såsom indikeras med en flamma. 1 ugnen ll bildad magnesiumånga under atmosfärstryck leds till en kondensor 18 där den kondenserar till ﬂytande primärt magnesium for vidare rafﬁnering direkt i sitt flytande tillstånd. 531 423 2 together. The fired dolomite comes from a calcination furnace 12 where the dolomite is burned to CaO-MgO, (calcined) and FeAl comes from an electric furnace 13 which may be, for example, a DC furnace or a ferroalloy furnace such as a shaft furnace for CaCl 2 production. This furnace 13 is charged with anthracite (carbon) and slag from furnace 11. That slag consists of CaO, AlzO 2 and residual MgO and FeAl (for example 5% by weight of Al). The FeAl which is discharged from the furnace 13 and granulated before it is charged to the furnace l 1. Calcium carbide is formed in the furnace 13 and drained. Residual magnesium in the slag from the furnace 11 is evaporated in the furnace 13 together with CO and passed through an exhaust duct 14 with a cooler 15 and an electrolyte 16. Mg and CO in the exhaust gases react on cooling back to MgO and C which are collected in the electrolyte as solids. The collected mixture of magnesium oxide and carbon is mixed with the dolomite which is charged to the calcination furnace. CO remains that are recovered from the exhaust duct and can be used as fuel as indicated by a flame. Magnesium vapor formed in the furnace 11 under atmospheric pressure is led to a condenser 18 where it condenses to surface primary magnesium for further refining directly in its liquid state.

Den i ugnen 13 bildade kalciumkarbiden, CaCz, kan direkt användas för framställning av magnesium gas i en ugn 17 (exempelvis en induktionsugn) som chargeras med en blandning av krossat magnesiumsilíkat (exempelvis olivin) och den krossade kalciumkarbiden, lämpligen i form av briketter. Ugnen 17 kan vara en induktionsugn. Magnesium i gasfas från ugnen 17 leds till kondensom 14 för kondensering gemensamt med det magnesium i gasfas som kommer från ugnen 1 1. Andra biprodukter blir kalciumsilikat, CazSiOg i fast fas och kol i fast fas. Kolet kan eventuellt separeras från kalciumsilikaten och chargeras ugnen 13 som bränsle. Kalciumsilikatet är ett värdefullt mineral.The calcium carbide formed in the furnace 13, CaCl 2, can be used directly for the production of magnesium gas in a furnace 17 (for example an induction furnace) which is charged with a mixture of crushed magnesium silicate (eg olivine) and the crushed calcium carbide, suitably in the form of briquettes. The furnace 17 may be an induction furnace. Magnesium in the gas phase from the furnace 17 is led to the condenser 14 for condensation together with the magnesium in the gas phase coming from the furnace 1 1. Other by-products become calcium silicate, CazSiOg in the solid phase and carbon in the solid phase. The carbon can optionally be separated from the calcium silicate and charged to the furnace 13 as fuel. Calcium silicate is a valuable mineral.

Fe och Al cirkulerar mellan ugnarna ll och 13 utan att förbrukas.Fe and Al circulate between furnaces II and 13 without being consumed.

Ugnen 17 bildar en separat process for produktion av magnesium och ugnar-na 11,1 2,13 en annan separat process för produktion av magnesium. CaCg som används i ugn 17 kan tas från ugn 13 eller externt. Eftersom produktionsprocessen för producering av magnesium med ugn 17 fordrar kalciumkarbid och processen for produktion av magnesium med ugnar-na 11,12 och 13 producerar kalciumkarbid är det en fördel att integrera de två processerna så att man får ett 53'l 428 3 internt kretslopp av kalciumkarbid. Båda processerna arbetar under atmosfárstryck, vilket förenklar processerna och gör dem säkrare.The furnace 17 forms a separate process for the production of magnesium and the furnaces 11.1 2.13 another separate process for the production of magnesium. CaCg used in furnace 17 can be taken from furnace 13 or externally. Since the production process for the production of magnesium with furnaces 17 requires calcium carbide and the process for the production of magnesium with furnaces 11, 12 and 13 produces calcium carbide, it is an advantage to integrate the two processes so that a 53'l 428 3 internal cycle of calcium carbide. Both processes work under atmospheric pressure, which simplifies the processes and makes them safer.

Den beskrivna karboterrniska processen for rnagnesiumproduktion får följande totala reaktion: 2CaO~MgO (bränd dolomit) + MggSíOrr (olivinsand) + 4 C = 4 Mg (produktl) + CazSiOﬂprodukt 2) + 4 CO (energi)The described carbothermal process for magnesium production has the following total reaction: 2CaO ~ MgO (burnt dolomite) + MggSíOrr (olivine sand) + 4 C = 4 Mg (product) + CazSiO product 2) + 4 CO (energy)

Claims

A carbothermal metallurgical process for producing liquid primary Mg, in which dolomite is burned to a mixed oxide CaO-MgO and a production furnace (11) is charged with this mixed oxide together with a FeAl alloy and gaseous Mg is taken out of the furnace. at atmospheric pressure and condenses it to liquid Mg, characterized in that a second furnace (13) is charged with carbon and with slag from the first furnace whereby liquid FeAl alloy is reduced out in this second furnace and the production furnace (11) is recharged and calcium carbide is drained from the second furnace (13), and that the calcium carbide formed in the second furnace (13) together with magnesium silicate type mineral is charged to a third furnace (17) and evaporated Mg from this furnace is allowed to condense to liquid Mg under atmospheric pressure.

A process according to claim 1, characterized in that the magnesium silicate consists of olivine sand.

A process according to claim 2, characterized in that crushed calcium carbide and olivine sand are mixed and formed into briquettes which are charged to the third furnace (17).

A process according to any one of the preceding claims, characterized in that the exhaust gases from the second furnace (13) are led to a cooler (15) where evaporated Mg and CO react back to MgO and C and are collected in a filter (16) and returned to an oven (12) for burning together with the dolomite.