Fragmentering av skrot/Shredding

Mapping and development of the shredder product
streams

Project leader: Per Nordenfelt, Minpro AB

Introduction
The unit operations of mineral processing are based on well-established theories concerning the comminuting, screening and classifying, sorting and separating of solid particles. The properties of particles such as colour, hardness, density, electrical properties, magnetic susceptibility, surface chemistry etc. are utilized in these operations.

This is true also for shredding, sorting and recycling of complex scrap. However, the methods employed are highly specialized and developed for this industry only. A general knowledge of the entire range of technologies and their potential in the field is missing. Therefore, information regarding these specialized methods has to be collected and compared to the general knowledge.

Goals
The main objectives are to raise both the quality and quantity of the recycled iron and steel, other ferrous and non-ferrous metals and alloys, as well as processing of reducing shredder residues to maximize the recycling rate and minimize the amount of total wastes to be landfilled. The objectives can be achieved by improving the precision of separation and minimize the quality variations in the processing of scrap.

The strategy will be based on three principles:

Stratifying of data in order to identify the main causes if variations, characterizing the compounds of shreds, and detail understanding of the shredding and separating consequences.
Experimenting, that is planning, performing and evaluating tests
"Divide and conquer", that is a closer examination and testing for selected parts of the process.

As a result increased degree of recycling, better utilization of alloying elements and reduction of tramp and harmful elements in the following steps in the steel eco-cycle is expected.

For the end user of shredded scrap, that is the electric arc furnace steel producer, the results will be less consumption of high quality scrap from virgin material and less energy consumption. This leads to lower costs and less environmental impact.

Industrial
To deliver methods to increase the value of the shredded scrap for steel production and decreases the environmental impact of the shredding plant.

Environmental
To decrease the emissions of carbon dioxide by 1260 ton/year and the electricity consumption by 9500 MWh/year. (Estimated effect + 10 years from 2004, for Swedish steel- and scrap handling industry).

Work plan

The following approach is considered.

1. A thorough mapping of all product flows of a shredder plant
2. Sampling and examining of products
3. Development of a process idea
4. Laboratory testing of unit operations on the sampled products
5. Pilot plant tests
6. Evaluating on site

This program will be realized in close cooperation with Stena Gotthard.

1. Mapping of product flows
All information from shredder operation already available will be collected and studied for the project. The priorities will be to consider the needs for steel producers.

From this starting point it has to be decided what further information has to be collected by sampling, assaying etc.

2. Sampling and examining
The scope and practical implementation of the sampling program will be decided together with Stena Gotthard in accordance with the strategy outlined above. This also goes for the assaying program. In some cases, upgrading of the Minpro assaying facilities is needed, e.g. supplementary x-ray equipment for rapid evaluation of scrap quality.

Together with Stena Gotthard, Minpro has already worked out a method for quality control of SLF. Experience from that project can be put at use here.

3. Development of process ideas
The outcome of the mapping and sampling will provide a base for development of process ideas.

4-5. Laboratory and pilot plant testing of unit operations on the sampled products
The Minpro facilities are well equipped and experienced operators are employed to implement the equioment and develop the process ideas in bench pilot plant scales. However, some special apparatuses from shredding plant operation may be needed.

6. Evaluation on site
After careful evaluation of the results achieved from laboratory and pilot plant tests, considered developed processes shall be tested at shredding site.

If possible, the testing ought to be performed parallel to the ordinary plant operation.

Deliverables for 2004-2008

The project will generate a number of reports, published after each stage. There will be a build up of scientific and practical knowledge for improving the quality of the scrap to be fed for steel production, improving the quality and quantity of the other non-ferrous metals produced by shredding plants, increasing the rate of recycling for light fractions, and reducing the amount of total wastes to be disposal with respect to energy conservation for Swedish industries.

Deliverables for 2004-2005
R&D activities	Status
A report presenting the results of sampling and analyses of shredder plant streams. Including also suggested process ideas based on the results.	Draft report. H.R. Manouchehri "Looking at Shredder Plant Configuration and its Performance for Developing Shredder Product Stream" (An overview)
The second report contains of the configuration of the 4 different shredding plants in Sweden, i.e. Halmstad, Hallstahammar, Huddinge owned by Stena Gotthard AB, and Skelleftehamn owned by Kuusakoski.	Draft report, H.R. Manouchehri "Mapping and Development of Shredding Product Streams; Four Shredding Plants in Sweden (What should be done for better performance of the plants?)" These plants were mapped and explained in details. The first part of the report reviews different aspects such as steel recycling and energy, recycled material for iron and steel production, material construction for different obsoletes, etc., in order to define their roles in recycling schema. In addition a general perspective for the recycling costs is presented and it is shown how recycling cost is affected by a factor named "Products factor", which is a function of product complexity and product size. WIthin the second part, the flow-sheets for the visited shredding plants are mapped and discussed in details. Finally two main strategic scenarios for recycling are addressed.
Deliverables for 2006
R&D activities	Status
Investigations: By sampling and analysing of shredder plant streams we will investigate the possibilities to attain: - higher scrap density. - lower levels and less variation of harmful elements, mainly copper. - environmental improvements of SLF Reports covering the results of sampling and analysing of shredder plant streams.	Samples were obtained from shredding plant in Halmstad in accordance with complete understanding of how to take and prepare representative samples form a plant, using Gy's theory for sampling. Sampling was done carefully in order to have a representative sample for further study, Characterizing and separation tests were/are conducted to see the possibilities to have a high quality product to be fed to EAFs. Main concerns are to reduce the amount of impurities and increase the density for the EAFs feed. A comprehensive report on sampling and then on separation tests will be prepared and delivered by H.R. Manouchehri before ending 2006.
Deliverables for 2007
R&D activities	Status
Assessment and evaluation of the results achieved and finalized the test results on ferrous and non-ferrous metals recovery of the feed obtained from shredding plant in Halmstad (STENA Plant). The goals are to gain Higher scrap density Lower levels for impurities High recovery of non-ferrous Environmental protection through having less ASR (SLF) by higher recovery of the metals and recycling of ASR by physical methods	The results indicated that classification of the shreds before magnetic, eddy current, and other physical separations would be beneficial in improving the quality quantity of materials for metallurgical applications. However, the recycling quantity is also improved. Furthermore, by changing the configuration of separating device as well as increasing or decreasing the magnetic force for both eddy current and magnetic separators that are the two major devices for separating ferrous and non-ferrous metals, including different steels, the quality and quantity of products can be improved. Promising results were achieved that will be submitted by reports.
Deliverables for 2008
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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