Vanadinutvinning/Recovery of Vanadium
Recovery of vanadium and fully use of slag component in BOF-slag
Project leader: Guozhu Ye, MEFOS
Introduction
The Swedish BOF-slag contains about 5% V2O5 which corresponds to 2,8%V. The annual production of BOF-slag in Sweden is 350-400 000 tons. About 50% of the BOF-slag, normally the coarser fraction of >6-7mm, is recycled to the blast furnace process for fully utilization of the excess amount of lime in the slag. The recycling rate is limited by the tolerance for phosphorous and vanadium accumulation. The fine fraction is normally disposed. Disintegration and high vanadium content are the main problems for external use of the slag.
The total vanadium content in the disposed Swedish BOF-slag is about 5 millions kilogram. With the current vanadium price of 40 US$, it corresponds to a total value of 200 millions US$ which is lost in the slag yards per year.
For one ton BOF-slag, there is also about 300 kg excess amount of burnt lime. This corresponds to a total amount of 56 000 tons of burnt lime. A fully use of this in the steelmaking process will provide a potential saving of more than 100 000 ton CO2 emission and about 140 MWh of energy per year.
The future steelmaking will be characterized by higher energy cost, demand for lower Green House Gas (GHG) emissions and increased cost of dumping. It is in this context this project is proposed.
Goals
General
The goal of this subproject is to develop new and reliable methods for metal and mineral recovery of the Swedish BOF-slag, special attention will be paid on vanadium recovery and the use of treated slag for internal and /or external utilizations.
Industrial
To deliver a cost efficient method for production of ferrovanadium based Swedish BOF-slag and this will enable and facilitate the recycling and selling of the BOF-slag.
Environmental
To annually save the emissions of carbon dioxide by about 100 000 tons, the energy consumption by about 140 000 MWh and the consumption of limestone by 100 000 tons at 2014.
Also about 5000 tons of vanadium will be recovered per year.
The overall work planThe work group of this subproject consists of key persons of the involved industrial partners in Sweden and Finland. An overall work plan with work packages, tasks and detailed budgets for each task has been provided based on discussion and decisions of the working group.
Detailed work plan for 2008
The main activities for 2008 will be:
- Continuation of the initial industrial trials of hot slag reduction at SSAB steelwork in
Luleå
- A pilot test at MEFOS in week 0826 has been planned, the final decision on this
activity will be made in the next committee meeting in March 2008
- Continuation of the V-thermodynamics studies, more experiments in laboratory scale
for activity measurement and valence determination of vanadium will be performed
- LTU and SSAB Merox will concentrate on slag procuts after V-recovery: properties
and potential applications
- Summary of "Etapp I" and preparation for Etapp II.
Additional activities supported separately by the industrial partners and MEFOS:
- V-thermodynamics will continue with a budget of about 1,4 MSEK (of a total
2,25 MSEK for 2007-2008)
- Pilot tests at MEFOS week 0826, about 1 MSEK will be needed, the decision for this
will be made in the next meeting, in March 2008.
The deliverables will be suggestions for new alternative ways to extract valuable metals like vanadium from the BOF-slag based on the results from the research activities according to the Project Work Plan.
The deliverables will be in kinds of annual MISTRA reports, final project report, meetings, seminars, publications and technology transfer to the industry.
Deliverables for 2004 - 2005
R & D activities | Status |
| 1. V-project | |
| A state of the art report on V-extraction from BOF-slag including available technologies, thermodynamic data for the concerned metallurgical systems | The report was delivered in November, 2005'
|
Initial results small scale tests on reduction of BOF-slag and selective oxidation of V in the obtained Fe-V-Mn-P alloy
| - theoretical modelling on slag reduction has been performed |
| Initial results from investigation on possibility of prepare a pure FeO*V2O3 spinel for direct FeV-production | Initial test has been made for characterization.The deliverable was a M.Sc. thesis, Luleå University of Technology, "Vanadinutvinning ur LD-slagg" by Samuel Jonsson, (2006:127 CIV ISSN: 1402 -1617 ISRN:LTU-EX—06/127) |
| Initial results from tests on possibility of V-enrichment on a targeted mineral phase
| Initial results shown that V could be concentrated to up to 15-33% in two V-enriched phases (3CaO*V2O5 in solid solution with 3CaO*P2O5). This work has been published in Journal of Ironmaking and SteelmakingConcentrating of Vanadium Oxide to Vanadium Rich Phases by Addition of SiO2 in Converter Slag, Ironmaking and Steelmaking, Vol 2, 2007
|
| Mechano-chemical treatment: - Studies on the effect of mechanical treatment on physical and chemical properties of the oxide minerals in the steelmaking slags of interest - Initial results from pilot tests | Initial tests on LD-slag was performed in November and December, 2005.
|
Additional deliverables
| - A RFCS-proposal has been prepared and sent to the EU-commission in Brussels with partners from Italy and Slovenia - A two-days seminar on V-extraction, focusing on extraction from Swedish LD-slag has been successfully arranged in Stjärnholm during April, 2005 |
Deliverables for 2006
R & D activities | Status |
V-P separation | A master thesis work on this subject has been carried out during 2006 at MEFOS: "Selective Oxidation of Vanadium prior to Iron and Phosphorus" by Mikael Lindvall (2006:288 CIV ISSN: 1402 -1617 ISRN:LTU-EX—06/288) Small scale and initial pilot tests have been performed and evaluated. The aimed V/P-ratio>500 and V/Fe-ratio>1 in the vanadium rich slag has been reached. More tests to reproduce the promising results are planned to be carried out during end of 2006 and beginning of 2007. |
| Reduction of LD-slag Efficiency of reduction of BOF-slag using different reducing agents are tested in small and pilot scale | - A two-step reduction process concept for efficient slag reduction aiming at a slag product suitable for external use and efficient use of the reductant has been developed based on thermodynamic calculation and experiences from FeCr-industry |
| V-enrichment The solid solution between 3CaO*V2O5 and Ca2SiO4 is preliminary studied | This concept has been considered "too complicated" for a possible industrial process and has not been preferred by the working group. No more has been done on this subject, 2006. |
| Tornado Tornado trials are performed for BOF-slag and the possibility of Tornado concept for mineral separation evaluated | MEFOS has carried out the initial trials. The chemical analysis showed however that the slag samples might have been contaminated by carbon. Probably we have to repeat the trails. |
| Additional deliverables Thermodynamic data for V-bearing slag system, financed by industrial partners | - Visit to CRCT group in Montreal, Canada, May, 2006 - A pre study report ready - A plan for continued work on the field has been prepared - A two-days seminar on the subject will held in the end of 2006 |
Deliverables for 2007
R & D activities | Status |
V-P separation | Additional trials at 150 kg HF-furnace have been performed. Selective oxidations tests covered the whole range of <1%V to 8%V. The targeted ratios of V/P>500 and V/Fe>1 in the prepared slags could be achieved and the results have been reproducible. A final report on selective oxidation will be delivered in the beginning of November. |
| Reduction of LD-slag - LTU will continue the selective reduction tests in lab-scale | LTU has performed all trials promised, a summary report has been delivered in September, 2007It was decided to combine the pilot test and the initial industrial trials. By doing this the most important parameters for further testing would be identified. These combined pilot and industrial trials have been going on at SSAB Luleå since the end of September. |
| Tornado The Tornado slag treatment for possible V-enrichment will be fully evaluated. | A report will be finished in the end of the year |
Additional deliverables
| - Experimental in 150 kg HF furnace at MEFOS in May, 2007 - Evaluation and valence determination of the slag samples - Equilibrium experiments for activity measurement of VOx in slags of interest, KTH - Valence determination of vanadium in China - Continued works also in 2008 in this field |
Deliverables for 2008
R&D activities | Status |
| Continue of additional deliverables 2007 | |
| Final report |
Fragmentering
/Shredding
... är en teknik som används för sönderdelning av skrot innan det smälts om till nytt stål. Genom att utveckla tekniken att finfördela skrotet kan variationerna i dess samman-sättning minskas och dess densitet ökas. Detta innebär att stålindustrin vid omsmältning av skrotet kan reducera både sitt elbehov och sina utsläpp av koldioxid.
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Laseranalys
/Laser analysis
... är en teknik som nu utvecklas för snabb bestämning av skrotets metallinnehåll. Stålindustrin väntas här få tillgång till en teknologi som kan komma att reducera behovet av jungfruliga metaller vid användning av skrot för tillverkning av nytt stål.
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Skrotflödet i samhället
/Recycling of steel
... är trots den höga återvinningsgraden föga dokumenterat. Med bättre kunskaper skapas förutsättningar för ökad återvinning och bättre styrning av skrotsorter för optimerad skrot-användning. Stålindustrin får möjlighet att effektivisera sin energianvänd-ning, stora ekonomiska värden tas till vara och miljöbelastningen minskar.
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Ytrening av skrot
/Surface cleaning of scrap
... är en teknik som skall bredda användningen av färg- och metallbelagt skrot som råvara till ett ökat antal stålsorter. För stålindustrin innebär användning av ytrenat och förvärmt skrot att både energi-användning och koldioxidutsläpp kan reduceras. Dessutom kan den avdrivna zinkbeläggningen komma att återanvändas inom zinkindustrin.
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Vanadinutvinning
/Recovery of Vanadium
Det finns låga halter av vanadin i svensk järnmalm. Genom utveckling av metoder för utvinning av vanadinet får en redan exploaterad naturresurs ett ökat miljövärde.
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Ökat metallutbyte vid smältning av stål/New melting processes EAF
... är teoretiskt möjligt genom metallurgisk manipulering under smältförloppet. Målet är att skapa sådana förhållanden att metaller överförs till stålet i stället för till slaggen. Detta innebär minskat behov av jungfruliga metaller, samtidigt som slaggen kan ges nya användnings-områden.
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Återvinning av slagg
/New slag systems EAF
... är tekniskt möjligt genom utveckling av nya metoder för lakning av olika metaller ur slagger, t.ex vanadin, och behandling av slagger så de kan användas som t.ex isoleringsmaterial eller cementråvara. Vissa slagger kan också användas som ny slaggbildare i stålprocessen, vilket minskar behovet av ny kalk. Återvinning av slagg miinskar både behovet av deponering och förbrukningen av nya naturresurser vid ståltillverkningen.
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Bevarande av alla ämnen i skrotet
/Tolerance of recycled elements
... är en teoretisk studie som skall söka klarlägga hur dessa kan nyttjas för att ge den färdiga stålproduktens önskade egenskaper. Om sådan "självlegering" blir praktisk möjlig kan de metalliska ämnen som finns i skrotet, och som normalt avlägsnas i processen, bevaras i det nya stålet. Detta innebär att förlusten av metaller ur stålets kretslopp kan reduceras.
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Nya höghållfasta stålprodukter
/Optimisation of hot rolling
... är ett forskningsprojekt som skall identifiera de processparametrar som vid värmning och valsning har störst inverkan på materialegenskaperna. De nya rönen kan ge stålindustrin möjligheter att med ökad precision framställa nya avancerade stålsorter och samtidigt minska förbrukningen av fossila bränslen.
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Metoder för lättare stålkonstruktioner
/High strength steel structures
...ska för avancerade höghållfasta stål utmynna i att stålets egenskaper kopplas till produkternas användning och återvinning ur ett livscykelperspektiv. Genom denna metodutveckling kan stål-, bygg- och verkstadsindustrin få nya infallsvinklar på användandet av stål som både kan minska behovet av jungfruliga metaller och reducera emissionerna vid såväl tillverkning som användning av produkterna.
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Miljövärderingsanalyser
/Environmental evaluation
I. Methodology for evaluation of environmental impact
...ska påvisa Stålkretsloppets miljövärde med beaktande av ekologiska, tekniska och sociala faktorer. Miljövärderingar ger forskare, industri, användare och samhället i övrigt möjlighet att värdera såväl stålets nytta för miljön som dess belastning på miljön ur ett livscykelperspektiv. En metod som gör miljövärderingar tillgängliga för objektiva beslut.
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II. Conjoint analysis as a decision tool for evaluation of environmental performance of for instance experts and consumers preferences
... tar fram en metod för att mäta olika experters och andra intressenters attityder till och värdering av komplexa miljöfrågor.
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