a9aa87f8-2daa-4634-83a4-51659ebfb3d5Aluminium clean scrap remelting & casting (2010)remelting of clean scraptechnology mixAluminium scrap to ingotProcessesIndustry dataEAAThis process considers processing of clean aluminium scrap in europe//www.eaa.net/upl/4/en/doc/EAA_Environmental_profile_report_May08.pdf91The data set represents the European specific situation, focusing on the main technologies and the legislative boundary conditions.Foreground System:
New scrap (also called process scrap) is surplus material that arises during the production and fabrication of aluminium products up to the point where they are sold to the final consumer. Thus extrusion discards, sheet edge trim, turnings, millings and dross could all be described as new scrap.
Old scrap is the aluminium material which is recovered after an aluminium product or component has been produced, used and finally collected for recycling. Old scrap could be a used aluminium beverage can, a car cylinder head, window frames or electrical conductor cable.
Scrap recycling route and corresponding models:
Most new aluminium scrap comes into the recycling industry directly from the fabricators. It is therefore of known quality and alloy and is often uncoated. It can then be melted with little preparation, apart perhaps from baling. Such scrap are usually collected by the so-called remelters and melted in reverbatory furnaces in order to produce new wrought aluminium alloys. Some new scrap that arises during semi-finishing processes may be coated with paints, ink or plastics. This scrap can be decoated by passing scrap through an oven or a mesh conveyer whilst hot gases are circulated through the mesh to volatilise or burn off the coating. De-coating is usually the only significant scrap preparation step which can be applied to the scrap input by the remelters. No scrap preparation phase is included.
Old aluminium scrap comes into the recycling industry via a very diversified and efficient network of metal merchants and waste management companies which have the technology to recover aluminium from vehicles, household goods, etc. This is often done using heavy equipment such as shredders, together with magnetic separators, to remove iron, sink-and-float installations, or by the use of eddy current installations to separate aluminium from other materials.
After collection, sorting and preparation, these old scrap are usually purchased by the so-called refiners and are melted into casting alloys, also called foundry alloys. Refiners recycle not only scrap from end-of-life aluminium products but also, scrap from foundries, turnings, skimmings (dross) and aluminium metallics. The second model called scrap recycling will specifically address this recycling route organised through the refiners.
Furnace technologies:
Several melting processes are used. The choice of process depends upon a number of variables. These include the composition of the scrap, the processes available within a given plant, and economic and scheduling priorities. Molten metal fluxing (to treat the molten metal: chemical adjustment, cleaning, yield maximisation, degassing, etc.) and filtration technology (to remove any unwanted materials prior to casting) is developed to produce aluminium alloys of the correct quality.
Remelters use mainly reverbatory furnaces so that the scrap remelting model is based on this furnace technology only. Refiners use a combination of rotary and reverbatory furnaces which represent about 90% of their furnace technology while induction technology is quite marginal. As a result, the scrap recycling model is based on a mix of rotary and reverbatory furnace technologies.
The temperature of the molten metal is adjusted and alloying additions may be made with a combination of primary metals, recovered metals and master alloys to ensure the correct chemical composition of the melt.
The main co-product from the reverbatory furnaces is the dross while rotary furnaces which use salt as fluxing agent, produces salt slag. Both co-products are usually treated in order to recover the aluminium metal and to regenerate the salt. Such treatments are part of the 2 models.
Products from the aluminium recycling industry:
Whether billets or slabs are produced by primary aluminium smelters or remelters, the alloy type produced is still only a function of the composition of the metal and the input added in their respective cast houses. Filtration, degassing, casting and homogenising technology ensure equivalent product quality.
The aluminium refiners convert most of their materials into foundry ingot, generally based on the aluminium-silicon alloy system with additions of other metals such as copper and magnesium. These ingots, complying with national, international or aerospace specifications, are used to produce aluminium castings. The casting processes include sand and permanent mould casting, high- and low-pressure casting and investment casting.
The actual mix of recycling techniques applied to a specific product depends on many factors. The treatment of recycling in each specific LCA study should preferably be discussed with aluminium industry representatives (more information at lci@eaa.be)
Dross recycling and salt slag treatment:
In absence of fluxing salt, melting aluminium usually produces residues such as dross or skimmings which is mainly composed of aluminium oxides and entrapped aluminium metal. Depending on the scrap input quality and size, between 20 and 100 kg of dross can be produced per tonne of ingot with a metal content varying from 30 to 60%. Aluminium metal contained in dross or skimmings, is recycled as part of the aluminium refiners operations. Large pieces of metal are separated from cool skimmings by manual sorting before skimmings are fed to impact or ball mills in which the more friable aluminium oxide is ground up; finer metal fractions may then be recovered with subsequent screening operations. Aluminium metallics, as a product of skimmings recycling operations, are recovered by a variety of methods with varying yield. Skimmings can also be fed directly into rotary furnaces and treated with more or less salt flux. Specific data have been also collected to model dross/skimmings recycling.
Salt flux is used mainly in rotary furnace in order to clean the melt and to collect the contaminants within the so-called salt slag. Salt slag contains between 5 and 20% of aluminium metal. Most of the salt slag is treated to recover the aluminium metal. This treatment includes a crushing and grinding process aiming at recovering the metal granulate which contains about 80% of aluminium metal. About 75% of the metal is recovered in the metal granulate. This metal granulates are melted in rotary furnaces. The non-metallic residue is then leached and the residual metal is oxidised. The oxides and others insoluble compounds are then separated from the leaching solution through filtration. The last step consists in a crystallisation process to regenerate the salt flux. Specific input and output data have been collected in order to model this salt slag treatment and associated aluminium recovery.
The background system is addressed as follows:
Electricity, Thermal energy: The electricity (and thermal energy as by-product) used is modelled according to the individual country-specific situation. The country-specific modelling is achieved on multiple levels. Firstly the individual power plants in service are modelled according to the current national grid. This includes net losses and imported electricity. Second, the national emission and efficiency standards of the power plants are modelled. Third, the country-specific fuel supply (share of resources used, by import and / or domestic supply) including the country-specific properties (e.g. element and energy contents) are accounted for. Fourth, the import, transport, mining and exploration processes for the energy carrier supply chain are modelled according to the specific situation of each power-producing country. The different mining and exploration techniques (emissions and efficiencies) in the different exploration countries are accounted for according to current engineering knowledge and information. Steam: The steam supply is modelled according to the individual country-specific situation with regard to the technology efficiencies and energy carriers used. Efficiencies range from 84% to 94% in relation to the representative energy carrier (gas, oil, coal). Coal, crude oil and natural gas used for the generation of steam are modelled according to the specific import situation (see electricity). Transports: All relevant and known transport processes used are included. Overseas transport including rail and truck transport to and from major ports for imported bulk resources are included. Furthermore all relevant and known pipeline and / or tanker transport of gases and oil imports are included. Energy carriers: Coal, crude oil, natural gas and uranium are modelled according to the specific import situation (see electricity). Refinery products: Diesel, gasoline, technical gases, fuel oils, basic oils and residues such as bitumen are modelled via a country-specific, refinery parameterized model. The refinery model represents the current national standard in refinery techniques (e.g. emission level, internal energy consumption,...) as well as the individual country-specific product output spectrum, which can be quite different from country to country. Hence the refinery products used show the individual country-specific use of resources. The supply of crude oil is modelled, again, according to the country-specific crude oil situation with the respective properties of the resources.The process is a partly aggregated remelting process converting Aluminium scrap to secondary ingot which can be used in all secondary aluminium applicationsPartly terminated systemAttributionalnonenone100.02010The dataset covers gate-to-gate system of Aluminium recycling in Europe. Dataset includes data partially aggregated by the EAA and the overall quality is very good. Dataset can be used as representative for average European recycling technology of aluminium scrap. Dataset should be reviewed for potential technology changes in 10 years.All relevant flows quantifiedEAAThis dataset can be used for all LCA applications requiring European Aluminium recycling data.thinkstep2016-01-01T00:00:00+01:00ILCD format 1.1thinkstepthinkstep2016-01-01T00:00:00+01:0010.00.000Data set finalised; entirely publishedEAAtrueOtherGaBi (source code, database including extension modules and single data sets, documentation) remains property of thinkstep AG. thinkstep AG delivers GaBi licenses comprising data storage medium and manual as ordered by the customer. The license guarantees the right of use for one installation of GaBi. Further installations using the same license are not permitted. Additional licenses are only valid if the licensee holds at least one main license. Licenses are not transferable and must only be used within the licensee's organisation. Data sets may be copied for internal use. The number of copies is restricted to the number of licenses of the software system GaBi the licensee owns. The right of use is exclusively valid for the licensee. All rights reserved.Aluminium ingot (secondary)Output110.000Mixed primary / secondaryUnknown derivation