Life Cycle assessment A Gate to Gate Evaluation Of Primary Aluminum through Smelting

Prepared by: Omid Emadinia Master student in metallurgical engineering

Professor: Dr. Belmira Neto

1st Semester of 2011-12

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Contents Abstract ... 3 Introduction .. 3 Background ... 4 Limitations of this assignment . 4 Life Cycle Assessment (LCA) .. 4, 5, 6 The benefits of LCA LCA phases

Aluminum products cradle to gate life cycle . 6 Aluminum smelting process ... 7, 8 Anode paste production .... 8 The goal and scope of this assignment .... 9 Life cycle inventory of this assignment . 9, 10 Data collection Validation Calculation

Life cycle impact assessment (LCIA) of this assignment .... 11, 12, 13 Selected categories explanations Classification Characterization Normalization

Conclusion ... 14 References ... 15

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Abstract LCA is a systematic tool that enables the analysis of environmental loads of a product throughout its entire life cycle and the potential impacts of these loads on the environment. In this study a gate to gate environmental analysis from the smelting aluminum stage is carried out. This aluminum production phase is the most electricity consumable step in the aluminum production cycle. Both the aluminum production process and the LCA methodology used to evaluate the environmental impacts are explained briefly. The inventory data has been extracted from International Aluminum Institute INVENTORY DATA for 2005. Information from other prospective resources was hired to validate the data. By the normalization of LCIA which has been determined as the final step of this assessment we will see hydrogen fluoride within the eco-toxicity category impacts caused by the primary aluminum smelting process has the highest impact on the worldwide. In this job the impacts of the inputs including electricity are not considered because, to engage their impacts specific software is needed which is far from the purpose of this job. 1. Introduction Traditionally, products were designed and developed without considering their adverse impacts on the environment. Factors considered in product design included function, quality, cost, ergonomics and safety among others. No consideration was given specifically to the environmental aspects of a product throughout its entire life cycle. Since, in developed and modern countries some indices such as sustainability, quality of life, environment and energy have been considered important, finding out how the production of materials and related products, processes and services affect the environment helps sustainable development. According to The World Business Council sustainable development is defined as ensuring a better quality of life for everyone, for now and for generations to come. The awareness of the environmental impacts of the processes associated with extracting, producing, manufacturing and using materials, products and services help to protect the environment. The analysis of both consuming raw materials and energy used in these processes and the outputs; products and emissions to the air, water and soil is an approach to evaluate the environmental impacts called life cycle assessment so that in this methodology the production and consumption are considered as the two sides of a single coin as a Cradle to Grave model. This kind of evaluation is performed since without addressing environmental impacts from the entire life cycle of a product, even for the product design, one cannot resolve the environmental problems causing from the production and consumption of the product. Aluminum is a metal which contributes as a vital material in many aspects of human life. More comfortable facilities e.g. modern fast and low energy consume transportation systems are produced by aluminum and even it has been useful to fulfill human`s dreams in different areas like space industry. The extent of aluminum applications are due to possessing good physical properties; light weight, electrical and thermal conductivity and even good mechanical properties like malleability in the pure form or high strength in its alloy compounds. Moreover, aluminum is the third most abundant element and metal in the crust of the earth. Therefore, it has become the second most usable metal in the world.

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2. Background The concept of Life Cycle Assessment emerged in the 1970s as a way to assess the overall use of energy and materials by products or services, from "cradle to grave" (creation of raw materials to final disposal). Later, the method was extended to include environmental emissions to air, water, and solid waste (SETAC 1991). In 2000, the International Standards Organization (ISO) completed work on a series of standards that have become the general benchmark for the technique. 3. Limitations of this job Due to the lack of time as it is an assignment of environmental management course, the assessment has been considered limited and also some information was not found in the literatures to provide a semi comprehensive data for the intended material production. 4. Life Cycle Assessment (LCA) LCA is a technique to evaluate the environmental impacts of a product from its cradle where raw materials are extracted to its grave, the disposal. 4.1. The benefits of LCA In the evaluation of an existing system, significant impacts in the environmental life cycle become obvious. This helps in the prioritization of activities to improve environmental performance. In considering improvements to a system, trade-offs between improvements at one life cycle stage and increased impacts at another life cycle stage are revealed. In comparing two alternative systems with major environmental impacts at different life cycle stages, the assessment gives a comprehensive overview of the trade-offs between the two systems. Helpful in decision making Useful in marketing

4.2. LCA phases A life cycle assessment is a large and complex effort, and there are many variations. However there is a general agreement on the formal structure of LCA, the methodology of it according to ISO 14040 is in followed: Goal and scope definition: The goal and scope of the LCA study are defined in relation to the intended application. Inventory analysis: The inventory analysis involves the collection of data and the calculation procedures. The result of this phase is a table that quantifies the relevant inputs and outputs of the system under analysis. Impact assessment: The impact assessment translates the results of the inventory analysis into environmental impacts (e.g. ozone depletion). The aim of this phase is to evaluate the significance of environmental impacts. Interpretation: At this phase conclusions and recommendations for decision makers are drawn from the inventory analysis and impact assessment. 4.2.1. The definition of the purpose of the life cycle assessment is an important part of the goal definition. The goal of an LCA study shall unambiguously state the intended application including the reasons for carrying out the study. Definition of the functional unit is the foundation of an LCA because 4

we will understand what data we would need plus the functional unit sets the scale for comparison of two or more products might result in improving one product (system). The system boundaries will define the processes/operations (e.g. manufacturing, transport, and waste management processes) and the inputs and outputs are to be taken into account in the LCA. The input can be the overall input to a production as well as input to a single process - and the same is true for the output. Ideally, all processes associated with the product should be included. 4.2.2. Inventory analysis involves data collection and calculation procedures to quantify relevant inputs and outputs of a product system. These inputs and outputs may include the use of resources and releases to air, water and land associated with the system. The quality of the data used in the life cycle inventory is naturally reflected in the quality of the final LCA. The data quality can be described and assessed in different ways. It is important that the data quality is described and assessed in a systematic way that allows others to understand and control for the actual data quality. So far the boundaries for all activities should have been determined according to this table; Inputs Raw material Energy Smelting process Metallic aluminum Emissions Outputs

Date collection is time consuming and it should have been collected in check list. Inventory step also some calculating processes including normalizing, calculating the flows linking the activities, calculating the flows passing the system boundary and finally summing the resources used and outputs for the whole system to find out the environmental loads. 4.2.3. The significance of potential environmental impacts of a product system based on life cycle inventory results is evaluated by using LCIA. It consists of several phases; Category definition Classification Characterization Normalization Weighting 4.2.3.1. The life cycle impact assessment involves, as its first element, defining the impact categories. This may be achieved by cause and effect chains. List of impact categories according to SETAC-Europe 1996 Input related resources; Abiotic resources Biotic resources Land Output related categories; Global warming Depletion of stratospheric ozone Human toxicological impacts Eco-toxicological impacts Photo-oxidant formation Acidification Eutrophication Odor Noise Radiation Casualties 5

4.2.3.2. Classification is a qualitative step based on scientific analysis of relevant environmental processes. The classification has to assign the inventory input and output data to potential environmental impacts i.e. impact categories. It requires some knowledge of what kind of impacts pollutants and resource use lead to. 4.2.3.3. Once the classification step is completed, quantification of environmental impacts by each inventory parameter on the impact category is assessed. The characterization calculates the size of the environmental impact per category using equivalency factor or category indicators or characterization factors. In other words characterization provides a way to directly compare the LCI results within each category. Characterization factors translate different inventory inputs into directly comparable impact indicator; e.g. the calculations show that ten pounds of methane has a larger impact on global warming than twenty pounds of chloroform. Simply, it determines the amount of impact each one has on the environment in respect to the category that the emitted compound belongs. 4.2.3.4. Normalization communicates the magnitude of the environmental impacts caused by the system under study and relates the characterization results to a reference value, in the country or in the region. It helps to understand whether each category impacts caused by the studied product are large or small in relation to the total category impacts in the intended region where the product is produced and used. 4.2.3.5. Weighting aims to rank, weight, or, possible, aggregate the results of different life cycle impact assessment categories in order to arrive at the relative importance of these different results. It means that the relative importance of an environmental impact is weighted against all the other. The relative weights of the different impact categories are expressed by their weighting factors. 4.2.4. Interpretation is the fourth phase in life cycle assessment containing the following main issues: Identification of significant environmental issues Evaluation Conclusions and recommendations 5. Aluminum products cradle to gate life cycle The primary aluminum metal is the output of the smelting process on the alumina (Al2O3) as alumina itself is the product of digesting the bauxite (alumina refining) while the crushed and washed bauxite is extracted from mine. The aluminum produced in smelting will be refined to remove metallic and nonmetallic impurities and dissolved hydrogen in the casting unit then it is shaped into semi-shaped goods e.g. ingots. Final shapes are achieved through fabrication which may involve rolling of the metal into sheets, casting the metal into shapes, drawing the metal into wire, or extrusion of the metal to produce different shapes. In all these processes there are some materials and energy, electricity or fuel, as inputs then the output which is product plus recycles and emissions to the environment.

Figure 1: A cradle to gate plus recycling loop of aluminum metal

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Figure 2: A general overview on the inputs and outputs of the primary aluminum production

6. Aluminum smelting process All modern primary aluminum smelting plants utilize the process which was independently invented in 1886 by Charles Martin Hall (United States) and Paul Louis Toussaint Hroult (France) and underwent continual improvement over the years. Alumina is reduced by carbon into aluminum in electrolytic cells, or pots according to front equation: 2Al2O3 + 3C 4Al + 3CO2 The pot consists of a carbon block (anode), formed by a mixture of coke and pitch, and a rectangular steel box lined with refractory bricks and covered with carbon (cathode). An electrolyte consisting of cryolite, aluminum sodium fluoride (Na3AlF6), lies between the anode and the cathode. A direct current is passed from the anode through the bath to the cathode at low voltage but at very high current then it goes to other cells which are connected in series. Alumina is added into the bath in the amount of 2-6%. Aluminum fluoride and calcium fluoride are also added to lower the bath melting point. The temperature of the process is approximately 960 C. Reduction of aluminum ions produce molten aluminum metal at the cathode and oxygen at the anode, which react with the carbon anode itself to produce CO2 which goes to the atmosphere. AlF3 is also added to neutralize the effect of sodium oxide present as an impurity. The molten aluminum is periodically withdrawn from the cell by the vacuum siphon into the crucible of ingot casting section. Carbon in anode is consumed continuously but in cathode is not consumable and it is only deteriorated by electrolyte and should be changed after each 5 to 8 years. There are two primary technologies used to produce anodes for the Hall-Hroult process; Sderberg and prebake. Sderberg anodes begin as semi-liquid constructions that are continuously fed into the molten cryolite bath while Pre-baked anodes are preformed and hardened in gas-fired ovens at high temperatures. Prebaked anodes are then fed into the cryolite bath. The major difference is that the Sderberg anode hardens with heat generated from the electrolytic process as it descends into the cryolite bath and the prebaked anode is hardened before use in the electrolytic cell. The newest and largest aluminum smelters generally use prebaked anodes, which are more efficient. To produce a prebaked anode, petroleum coke and pitch are blended together and baked in ovens. 7

The smelting process is the highest consuming amount of electricity among all processes in aluminum production, almost 96%. And the prebaked type anode technique uses less electricity than the Sderberg. Aluminum smelters typically use air pollution control system to reduce emissions. The primary system is typically a scrubber. Some plants use dry scrubbers with alumina as the absorbent that is subsequently fed to the pots and allows for the recovery of scrubbed materials. Other plants use wet scrubbers, which recirculate an alkaline solution to absorb emissions. The wet scrubbing process uses Fresh Water or Sea Water as input and result in corresponding Fresh Water or Sea Water discharges. Unlike dry scrubbers, wet scrubbers absorb carbon dioxide, nitrogen oxide and sulphur dioxide that are entrained in the waste water liquor (which is subsequently treated prior to final discharge). Scrubber sludge is landfilled. Figure 3: Pre-bake cells in aluminum smelting (to the left) and Sderberg cells in aluminum smelting (to the right)

7. Anode paste production The process for making the aggregate for briquettes or prebake blocks is identical. Petrol Coke is calcined, ground and blended with Pitch to form a paste that is subsequently formed into blocks or briquettes and allowed to cool. While the briquettes are sent direct to the pots for consumption, the blocks are then sent to a separate baking furnace. Baking furnace technology has evolved from simple pits that discharged volatiles to atmosphere during the baking cycle to closed loop type designs that convert the caloric heat of the volatile into a process fuel that reduces energy consumption for the process. Baking furnace use Refractory materials for linings, Fresh Water (input taken conservatively whether the water used is from fresh, underground, mine waste water, etc. sources) as cooling agent. Baking furnace accounts for most of energy consumption (Coal, Diesel Oil, Heavy Oil, Natural Gas, and Electricity). The common practise for pollution control from Anode baking furnaces is scrubbing with alumina and returning the alumina to the electrolysis process. In case of separate Anode baking plants this is replaced by coke and lime scrubbing, which is then returned to the process. For paste plants the common pollution prevention is coke scrubbing and returning the coke to the process. There are some plants still using Water scrubbing, but this is not best practise and not the common method. The water emissions from paste and anode plants come from the cooling of the paste or green anodes. 8

8. The goal and scope of the job This job is a part of a complete LCA and only intends to analyse the inputs and outputs of the smelting cells without considering both the anode production and the casting house data. The reason to choose smelting process among other stages in aluminum production is that of the metallic product of the process and it consumes electricity a lot. This evaluation is considered as a gate to gate assessment. 9. Life cycle inventory 9.1. Data collection; the smelting cell system, the energy and materials inserted in and the outputs, have been modeled schematically in figure4-right. The inputs to the smelting process are electricity, alumina and aluminum fluoride and electrode paste (carbon) and the outputs from the system (cell) are air and water emissions, by-products and solid waste. All data used here belong to Report no.8/2004 from Norwegian University of Science and Technology (NTNU) and all natural resources and pollutants are described in quantitative contents.

Figure4: The flowchart of primary aluminum production (to the left) and the boundary aluminum smelting cell (to the right)

The data of inputs and outputs shown in table 1 are obtained for the production of 1 ton aluminum. The electrolysis of alumina to produce aluminum is a dry process and no water is produced directly and by applying some techniques rainwater contaminations are prevented unless water is used in ventilation air water scrubbers and SO2 water scrubbers. Table 1: Inputs data as well as a comparison as validationInputs Alumina Anode material AlF3 Cathode carbon Refractory Steel for cathodes Electricity Fresh water Sea water Contents per one tonne aluminum NTNU 2004 IAI 2005 1925 Kg 1923 Kg 441 Kg 435 Kg 17.4 Kg 16.4 Kg 6.1 Kg 8 Kg 6 Kg 5.4 Kg (excluding SPL) 5.5 Kg 6.6 Kg 15.365 MWh 15.289 MWh 2.95 5.3 Kg 20.8 17.6 Kg IPPC 2009 1900-1930 Kg 390-440 Kg 13-30 Kg Not mentioned Not mentioned Not mentioned 12.9-15.5 KWh/Kg Not mentioned Not mentioned

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9.2. Validation; here, between the collected data and the information of other resources are compared to show the validation. They are; IAI Life Cycle Inventory-2005 and the European IPPC Bureau of 2009. 9.3. Calculation; it should be mentioned that here it is not needed to normalize the inventory data because, the information has already been related to one tonne of aluminum per year as the product and since there is only one process/activity so it is not possible to calculate the flows linking the activities and suchlike. Table 2: Outputs data as well as a comparison as validationOutputs per one tonne aluminum Air emissions NTNU 2004* Fluoride gases (or total fluoride considered HF)** 0.55 Kg Fluoride Particulate (AlF3&Cryolite) 0.5 Kg Particulates (dust)*** 3.3 Kg CO2 1626 Kg (in eq) NOX 0.35 Kg SO2 13.6 Kg Total PAH (Poly-aromatic hydrocarbons)/Carcinogenic 0.13 Kg CF4**** 0.22 Kg C2F6**** 0.021 Kg BaP (Benzo-a-Pyrene arises from anode consumption) 0.005 Kg Water emissions Fluoride as HF** 0.2 Kg Oil and grease 0.008 Kg Suspended solids 0.21 Kg PAH 0.003 Fresh water 3.2 Kg Sea water 20.9 By-products for external recycling Other by products 5.1 Kg Spent pot lining (carbon fuel, reused) 9.9 Kg Spent pot lining (Refractory brick, reused) 5.5 Kg Refractory material 0.5 Kg Steel sludge Solid wastes Aluminum waste Carbone waste Refractory-landfill SPL-landfill Scrubber sludge 6.9 Kg Not mentioned 4.7 Kg 4.6 Kg 1.2 Kg 17.3 Kg 13.7 Kg IAI 2005 0.55 Kg 0.49 Kg 3.7 Kg 1557 Kg (in eq) 0.32 Kg 14.9 Kg 0.29 Kg 0.13 Kg 0.013 Kg 2.6 g 0.32 Kg as F 0.008 Kg 0.2 Kg 1.64 g 4.9 Kg 17.6 Kg Not mentioned 4.8 Kg 4 Kg 2.3Kg(excluding SPL) 8.9 Not mentioned 2.6 Kg 6.9 Kg 0.5 Kg 13.2 Kg 4.7 Kg IPPC 2009 0.25-1.5 Kg Not mentioned 0.5-3 Kg 3 1.6-1.7*10 Kg 0.1-0.2 Kg 10-30 Kg Not mentioned 0.01-0.38 Kg Not mentioned 0.06-1 Not mentioned 0.1-0.5 Not mentioned Not mentioned Not mentioned Not mentioned Not mentioned Not mentioned Not mentioned Not mentioned Not mentioned Not mentioned Not mentioned Not mentioned Not mentioned Not mentioned

*Inventory results for world in 2003, the average of aluminum smelting by electrolysis and corresponding production of anode to produce aluminum in liquid form. **The type of fluoride is considered as HF in the environment. ***The size of the dust has not mentioned in the references and here it is assumed to be more than 10 micrometer which has less effect especially on human. ****According to the references these compounds are considered as PFC and since the type of it has not specified so it is assumed to be as PFC-4-1-12 Note: The data belongs to Pre bake technology

In this job for two reasons the information of the second column is considered as the inventory data; first it seems to be more complete and more clarified than two others as the goal is to evaluate only the smelting cell impacts on the environment.

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10. Life cycle impact assessment (LCIA) 10.1. Category definition; the following impact categories have been selected; Global Warming Potential (GWP) Acidification Potential (AP) Photochemical Ozone Creation Potential (POCP) also called Summer Smog/Photo-oxidant Eutrophication Potential (EP) Toxicity 10.1.1 Greenhouse gases (GHG) are atmospheric gas believed to contribute to climate change by increasing the ability of the atmosphere to trap heat. Different species of such gases, such as CO2 and methane (CH4) expressed as kilogram of CO2-equivalents, have abilities to trap heat. Global warming potential (GWP) is a measure of the relative effectiveness of a GHG to affect climate. The heat-trapping ability of 1 ton of CO2 is the common standard, and emissions are expressed in terms of CO2 equivalent. Although PFCs emitted from aluminum smelters are not considered toxins or ozone-depleting gases, they are considered to be GHGs. PFCs are of particular concern because they have a greater global warming potential (GWP) per unit of emission than carbon dioxide. It has been estimated that 1 t of CF4 has the equivalent GWP of 6,500 t of CO2 and that 1 t of C2F6 has the equivalent GWP of 9,200 t of CO2. 10.1.2. The acidification potential is a measure of emissions that cause acidifying effects to the environment. The major acidifying emissions are nitrogen oxides (NOX) and sulfur dioxide (SO2), as well as ammonia emissions that lead to ammonium deposition. 10.1.3. The Photochemical Ozone Creation Potential (POCP) measures the emissions of precursors that contribute to low level smog (also called Summer Smog). They are produced by the reaction of NOX and volatile organic compounds (VOC) under the influence of ultra violet light. 10.1.4. The eutrophication potential is a measure of emissions that cause eutrophying effects to the environment. The eutrophication of aquatic systems is primarily caused by excessive inputs of nitrogen and phosphorus (mostly as a result of over-fertilization) it leads to biological productivity. 10.1.5. This category is complicated due to including many types of impacts and is divided into human and eco-toxicity (aquatic and terrestrial) 10.2. The classification of the inventory data is shown in table 3. Since the analysis cells of smelting process are under control, the emissions will affect the environment so, the outputs are assigned to the categories. Since to determine the inputs impact especially electricity a software is needed so, the evaluation of them is not considered here. Table 3: the classification of inventory dataCategory Global Warming Potential (GWP) Acidification Potential (AP) Photo-oxidant (POCP) Eutrophication Potential (EP) Human Toxicity (HTP) Eco-toxicity (MAETP, FAETP & TETP) Inventory substances CO2 and CF4 + C2F6 as PFC NOX, SO2 NOX as NO2 and SO2 NOX as NO2 Dust, NOX as NO2, SO2, PAH and HF BaP, PAH and HF Resource Electrolysis Electrolysis Electrolysis Electrolysis Electrolysis Electrolysis

10.3. Characterization of inventory data is done according to the characterization factor from CML-IA Characterization Factors-LEIDEN University. Impact indicators are typically characterized using the following equation: Inventory Data Characterization Factor = Impact Indicators

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Table 4: the classification of inventory dataCategory (expressed relative to) GWP (Kg CO2 eq.) AP (Kg SO2 eq.) Emissions CO2 CF4 + C2F6 as PFC 4-1-12 NOX as NO2 SO2 Dust (PM10) NOX as NO2 SO2 PAH HF PAH PAH HF EP (kg PO4 eq.) POCP3-

Emissions contents (Kg) 1557 0.143 0.32 14.9 3.7 0.32 14.9 0.29 0.55 0.00164 0.00164 0.32 0.32 0.32 14.9 0.0026 0.29 0.55 0.00164 0.00164 0.32 0.32 0.0026 0.29 0.55 0.00164 0.00164 0.32 0.32 0.0026 0.29 0.55 0.00164 0.00164 0.32 0.32

Initial emission Air Air Air Air Air Air Air Air Air Fresh water Marine Fresh water Marine Air Air Air Air Air Fresh water Marine Fresh water Marine Air Air Air Fresh water Marine Fresh water Marine Air Air Air Fresh water Marine Fresh water Marine

Characterization factors 1 9.2*103

Impact (Kg) 1557 1315.6 0.16 17.88 3.034 0.384 1.4304 165300 1595 459.2 47.56 1152 1152 0.0416 0.7152 0.2288 493 2.53 45.92 0.0001968 6.08

HTP (kg 1,4-dichlorobenzene eq.)

0.5 1.2 0.82 1.2 0.096 5 5.7*10 3 2.9*10 2.8*10 2.9*10 3.6*10 5 4 3 3

HF NOX as NO2 SO2 BaP PAH HF PAH PAH HF HF BaP PAH HF

3.6*10 0.13 0.048 88 2 1.7*10 4.6 2.8*104

FAETP (kg 1,4-dichlorobenzene eq.)

0.12 19

2.2*10 3 1.4*10 3 4.3*10 7 4.1*10 5.5*103 4 7 7

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0.000704 3.64 1247 4 2255*10 9.02 39.36 1728*104 4

MAETP (kg 1,4-dichlorobenzene eq.)

PAH PAH HF HF BaP PAH HF

2.4*10 5.4*10

5.4*10 0.24 1 -3 2.9*10 2.1*10-3 -4 -5 -5

1728*10 -4 6.24*10 -4 2900*10 -4 0.1595*10 0.03444*10-4 -4

TETP (kg 1,4-dichlorobenzene eq.)

PAH PAH HF HF

8.1*10 4.5*10

0.013284*10 0.144*10 0.144*10-4 -4

4.5*10

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Table 5: The aggregation of the impacts within each categoryCategory Global Warming Potential (GWP) Acidification Potential (AP) Photo-oxidant (POCP) Eutrophication Potential (EP) Human Toxicity (HTP) MAETP FAETP TETP Eco-toxicity (MAETP, FAETP & TETP) The sum of the categories impacts 2872.6 18.04 0.7152 0.0416 168910.6084 57111299.02 547.7597008 0.2906591 57111847.07

Now the results are comparable in each category and the size of each environmental impact is determined per each category. 10.4 The normalization process expresses the impact indicator data in a way that can be compared among impact categories because; there will be no unit for the contents. This procedure normalizes the indicator results by dividing by a selected reference value. Here, the values of CML from 1995 are selected which is said are more precise and reliable. Table 6: The normalization according to the worldwide value in 1995Category (expressed relative to) GWP AP HTP Type of missions CO2 PFC NO2 SO2 Dust(PM10) NO2 SO2 HF PAH PAH PAH HF HF NO2 SO2 BaP HF PAH PAH PAH HF HF BaP HF PAH PAH PAH HF HF BaP HF PAH PAH PAH HF HF Initial emission Air Air Air Air Air Air Air Air Air Fresh water Marine Fresh water Marine Air Air Air Air Air Fresh water Marine Fresh water Marine Air Air Air Fresh water Marine Fresh water Marine Air Air Air Fresh water Marine Fresh water Marine Characterization Impacts 1557 1315.6 0.16 17.88 3.034 0.384 1.4304 1595 165300 459.2 47.56 1152 1152 0.0416 0.7152 0.2288 2.53 493 45.92 0.0001968 6.08 0.000704 3.64 2255*104 1247 9.02 39.36 1728*104 1728*104 6.24*10-4 0.1595*10-4 2900*10-4 0.03444*10-4 0.013284*10-4 0.144*10-4 0.144*10-4 Worldwide values for 1995 4.2*1013 3.2*1011 Normalized data 370.714*10-13 313.238*10-13 5*10-13 558.75*10-13 0.532*10-13 0.067*10-13 0.250*10-13 279.824*10-13 29000*10-13 80.561*10-13 271.092*10-13 202.105*10-13 202.105*10-13 2.97*10-13 74.5*10-13 1.144*10-13 12.65*10-13 2465*10-13 229.6*10-13 0.000000984*10-13 30.4*10-13 0.00352*10-13 0.0728*10-13 45.1*10-13 24.94*10-13 0.451*10-13 0.7872*10-13 345600*10-13 345600*10-13 0.02311*10-13 0.00059*10-13 10.74074*10-13 0.000127*10-13 0.0000492*10-13 0.000533*10-13 0.000533*10-13

5.7*1013

EP POCP FAETP

1.4*1011 9.6*1010

2.0*1012

MAETP

5*1014

TETP

2.7*1011

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Conclusion This study provides readers to be familiar to LCA methodology to evaluate the environmental impacts of producing primary aluminum as well as the process itself. Only the impacts of smelting process were quantified. By LCA finally it is seen that within these selected categories the HF emitted in water in the amount of 0.32 Kg per one tonne of primary aluminum produced by smelting, without considering the anode production and casting stages impacts over the environment, has the highest impact on the environment of the world in comparison with other emissions

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References The Hitch Hiker`s Guide to LCA Report no.8/2004 from Norwegian University of Science and Technology (NTNU) International Aluminum Institute INVENTORY DATA FOR THE PRIMARY ALUMINIUM INDUSTRY YEAR 2005 UPDATE European IPPC Bureau Non-Ferrous Metals Industry Draft July 2009 The aluminum industrys sustainable development report by IAI

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