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Random Sampling of Steel Scrap : A novel method of recyclingSirén, Patrik, Nguyen, John January 2013 (has links)
Today, the alloy content in steel scrap deliveries in Sweden are determined by the waste management company by test melts. Random sampling analysis (RSA) is an alternative method, under development, to determine the alloy composition of steel scrap. This method evaluates the alloy composition of the steel delivery based on a number of randomly chosen steel scrap unit. RSA is a surface analysis, it is done on a distributed area where with the help of a grid, marks the random steel scrap units for evaluation. This means that the surface fraction determines the odds of analyzing the steel scrap. In a previous study of RSA, 100 random pieces of scrap units was evaluated for its alloy composition with Optical Emission Spectroscopy (OES). These scrap deliveries were thereafter sent to an Electric Arc Furnace for melting. This was done to compare the RSA analysis with samples taken after scrap melting. The RSA study however assumes that the scrap units have the same weight. In this study, the weights of the scrap units in the RSA was assumed to have a variance. Using MATLAB® and the alloy composition data acquired from the old study, a simulation was made where 100 pieces and 100 analyses was made to see what the margin of error in comparison to the old study. Another goal with this study was to see if the variance of the weight had any relation to the absolute deviation of each element in the alloy composition. The results showed that there was no relation between the absolute deviation of each element and the weight distribution in the population. This indicates that there are other factors involved other than the weight distribution in the samples. The average margin of error for all the elements was calculated to 5.94% for the weight distribution of 0.1:0.1:10 kg. This indicates that RSA is accurate or close in analysis for old steel scrap deliveries even if the weight distribution is 0.1:0.1:10kg. The highest margin of error was obtained for W, Ce and Ti with a margin of error of 18.6%, 14.89% and 10.71% respectively. All the other elements had a margin of error beneath 10%. This indicates that for RSA on old steel scrap deliveries a margin of error of 10% would be a good benchmark on the accuracy of the analysis.
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Improved mapping of steel recycling from an industrial perspectiveGauffin, Alicia January 2015 (has links)
The results from this study show that it is possible to obtain data series on the steel scrap collection based on mass balance model on the crude steel production figures by steelmaking reactor type and additional knowledge on process metallurgy as well as information on inputs and outputs into the reactors with an area correlation coefficient of 0,91 compared to data obtained from trade statistics. Furthermore, the study shows that based on a new method it is possible to calculate the time duration of mass flows on a continuous basis. Furthermore, two complementary statistical dynamic material flow models that can be used to calculate the societal recycling rates of steel was constructed. These statistical models contribute to a standardized way of obtaining consistent results. The new models are able to segregate the non-recirculated amounts of steel into the hibernating steel stock available for future collection from the amounts of losses based on statistics. The results show that it is possible to calculate the amounts of steel scrap available for steelmaking at a given point in time. In addition, based on the new models it is possible to calculate recycling trends in society. Also, the models are able to calculate robust forecasts on the long-term availability of steel scrap, and test if forecast demand of steel scrap exceeds a full recovery. This due to that the steel scrap generation is a function of the collection rate of steel scrap. Also, a method for obtaining representative samplings on the alloy content in steel scrap called random sampling analysis (RSA) was developed. The results from the RSA show that it is possible to optimize the recovery of valuable elements in the production process of steelmaking based on the information on the composition of steel scrap. / <p>QC 20151020</p>
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Analysis on copper, lead and tin removal in steel scrap sorting : Technologies involved, environmental considerations and economic aspectsCavaliere, Giada January 2023 (has links)
With the urgency of cutting down CO2 emissions to reach climate neutrality by 2050, decarbonization of the steel industry is on the European Commission's agenda. Steelmaking accounts for 10 % of anthropogenic CO2 emissions and it is one of the most challenging sectors to decarbonize. A solution that could support this progressive shift is to put more trust into the electric arc furnace (EAF) process, which relies on steel scrap as the main feedstock, but currently it is only responsible for 40% of the EU steelmaking. The almost remaining percentage is taken by the blast furnace route. Multiple European blast furnaces are currently closing due to low demands, high competition on imports and extremely high energy prices for production due to the Russian invasion of Ukraine situation. This particular moment could the proper time for increasing the employment of the EAF process. Moreover, the latter could help to improve resource efficiency and circularity of steel scrap thanks to the usage of higher shares of it, creating a “closed loop” for the steel industry. The reality of using more steel scrap is not actually very far from where we are, however, this will not be easy to reach. In fact, to ensure that the steel scrap is recycled "infinite" times it must contain very low quantities of impurities, such as copper (Cu}, tin (Sn) and lead (Pb}. Most of the times, this does not happen. Thus scrap is diluted with virgin iron to disperse those unwanted elements. This practice leads to a gradual decline of steel scrap quality, which is not in accordance with what it has just stated above. To worsen this situation even more, forecast is predicting increasing quantities of Cu that will accumulate into the steel scrap streams, due to the expected rising electric vehicles production. The aim of the following thesis work is to set a model to design a potential sorting solution to provide a higher copper (the most annoying cause of concern) removal rate in steel scrap, considering the economic and environmental implications of its implementation in the industry. Nonetheless, the presence of even lead and tin will also be taken into account. Results showcases that it is possible to get better impurities removal compared to what it has been done in many EU steel scrapyards, with ballistic separation as an additional refining separation step. Moreover, it is also an economically convenient and easy implementable solution that would assure higher quality steel scrap downstream of the process and that would also bring substantial economic and environmental benefits. / Med det brådskande att minska CO2-utsläppen för att nå klimatneutralitet till 2050, står avkarbonisering av stålindustrin på EU-kommissionens agenda. Ståltillverkning står för 10 % av antropogena koldioxidutsläpp och det är en av de mest utmanande sektorerna att ta bort koldioxid. En lösning som skulle kunna stödja denna progressiva förändring är att sätta mer förtroende till den elektriska ljusbågsugnsprocessen (EAF), som är beroende av stålskrot som huvudråvara, men för närvarande är den bara ansvarig för 40 % av ståltillverkningen i EU. Den nästan återstående andelen tas av masugnsvägen. Flera europeiska masugnar stängs för närvarande på grund av låga krav, hög konkurrens på import och extremt höga energipriser för produktion på grund av den ryska invasionen av Ukraina. Just detta ögonblickkan vara fördelaktigt för att öka sysselsättningen av EAF-processen. Dessutom skulle det senare kunna bidra till att förbättra resurseffektiviteten och cirkulariteten för stålskrot tack vare användningen av högre andelar av det, vilket skapar en "sluten slinga" för stålindustrin. Verkligheten med att använda mer stålskrot är faktiskt inte särskilt långt ifrån där vi är, men detta kommer inte att vara lätt att nå. Faktum är att för att säkerställa att stålskrotet återvinns "oändliga" gånger måste det innehålla mycket små mängder föroreningar, såsom koppar (Cu), tenn (Sn) och bly (Pb). Oftast händer detta inte. Således späds skrot med jungfruligt järn för att skingra dessa oönskade element. Denna praxis leder till en gradvis försämring av stålskrotskvaliteten, vilket inte är i enlighet med vad den nyss har angett ovan. För att förvärra denna situation ännu mer, förutspår prognosen ökande mängder Cu som kommer att ackumuleras i stålskrotströmmarna, på grund av den förväntade ökande produktionen av elfordon. Syftet med följande examensarbete är att sätta en modell för att designa en potentiell sorteringslösning för att ge en högre kopparavskiljningshastighet (den mest irriterande orsaken till oro) i stålskrot, med tanke på de ekonomiska och miljömässiga konsekvenserna av dess implementering i industrin. Icke desto mindre kommer förekomsten av jämnt bly och tenn också att beaktas. Resultaten visar att det är möjligt att få bättre bortförsel av föroreningar jämfört med vad man har gjort på många stålskrotvarv i EU, med ballistisk separering som ett extra raffineringssteg. Dessutom är det också en ekonomiskt bekväm och lätt implementerbar lösning som skulle säkerställa högre kvalitet stålskrot nedströms om processen och som också skulle ge betydande ekonomiska och miljömässiga fördelar.
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Optimization of alloys recovery in steel scrap sorting : Technological, economic and environmental considerations for a better chromium, nickel and molybdenum recovery in steel scrapQuintè, Simone January 2023 (has links)
Today’s steelmaking industry is highly dependent on steel scrap supply. In order to reduce the greenhouse gas emissions (GHGs) deriving from the steel industry, it is of utmost importance to ensure that high percentages of steel scrap are recycled, reducing the reliance on the traditional ore-based steelmaking, which is significantly more environmentally impactful. To reach this goal, a better steel scrap quality has to be achieved during the sorting process. This thesis work aims to propose an optimized sorting process able to separate the stainless steel scrap from the carbon steel scrap, both obtained in the ferrous fraction after a magnetic separation. This improved sorting process would be able to sort different types of stainless steel scraps according to their alloying content, ensuring a better recovery of chromium, nickel and molybdenum for stainless steel production. This would lead to a considerable reduction of CO2 emissions for the stainless steel production. In addition, an economic benefit could be obtained from the optimized sorting process, obtaining steel scrap of higher quality and thus selling the scrap at higher price. In this thesis work, technological considerations are addressed in order to select the most suitable technology to reach significant improvements in alloy recoveries in steel scrap. An economic and environmental model is then used in order to showcase the possible economic and environmental impacts resulting from the implementation of the proposed optimized sorting process. The results obtained are encouraging, showing that this improved sorting would save high amounts of CO2 emissions deriving from raw materials extraction and production, and showing that good profits can be obtained from the selling of the different stainless steel scrap sorted. In the future, where an increased production of steel is expected, this process would be even more beneficial both for the economy and for the environment. / Dagens stål tillverkningsindustri är starkt beroende av utbudet av stålskrot. För att minska utsläppen av växthusgaser (GHG) från stålindustrin är det av yttersta vikt att säkerställa att höga andelar stålskrot återvinns, vilket minskar beroendet av den traditionella malmbaserade ståltillverkningen, som är betydligt mer miljöpåverkande. För att nå detta mål måste en bättre stålskrotskvalitet uppnås under sorteringsprocessen. Detta examensarbete syftar till att föreslå en optimerad sorteringsprocess som kan separera det rostfria stålskrotet från kolstålsskrotet, båda erhållna i järnfraktionen efter magnetisk separation. Denna förbättrade sorteringsprocess skulle kunna sortera olika typer av rostfritt stålskrot efter deras legeringsinnehåll, vilket säkerställer en bättre återvinning av krom, nickel och molybden för produktion av rostfritt stål. Detta skulle leda till en avsevärd minskning av CO2-utsläppen för produktionen av rostfritt stål. Dessutom skulle en ekonomisk fördel kunna erhållas från den optimerade sorteringsprocesser, att få stålskrot av högre kvalitet och därmed sälja skrotet till ett högre pris. I detta examensarbete behandlas tekniska överväganden för att välja den mest lämpliga tekniken för att uppnå betydande förbättringar av legeringsåtervinning av stålskrot.En ekonomisk och miljömässig modell används sedan för att visa upp de möjliga ekonomiska och miljömässiga effekterna av implementeringen av den föreslagna optimerade sorteringsprocessen. Resultaten som erhålls är uppmuntrande, och visar att denna förbättrade sortering skulle spara stora mängder CO2-utsläpp från råvaruutvinning och produktion, och visar att goda vinster kan erhållas från försäljning av olika sorterade rostfritt stålskrot. I framtiden, där en ökad produktion av stål förväntas, skulle denna process vara ännu mer fördelaktig både för ekonomin och för miljön.
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