Evaluation and Comparison of Environmental Impacts of Sand Casting Process using Life Cycle Assessment

D. Joshi and B. Ravi

Indian Institute of Technology Bombay, India

M.V.N.J. Rao and N. K. Nagar Shri G S Institute of Technology and Science, Indore, India

Copyright 2005 American Foundry Society ABSTRACT Foundries are considered to be resource intensive and emitting gaseous, liquid and solid wastes. The environment impact of a cast product during its entire life from raw material extraction to final disposal, can be evaluated in various impact categories (global warming, acidification, eutrophication, human toxicity, eco-toxicity, etc.) using Life Cycle Assessment (LCA) methods. The current LCA methods however, consider the casting process as a whole. In this work, a methodology for assessment and comparative evaluation of the environment impact of a specific combination of casting alloy, melting equipment, molding and core making process, and emission control has been developed. It covers all major hazardous air pollutants and particulate matter emitted in ferrous foundries. The methodology has been implemented in a web-based program, and demonstrated for a casting example. It is useful for evaluating the environmental impact of a cast product early in its lifecycle, thereby facilitating selection of the most benign combination of casting alloy and process steps. INTRODUCTION Foundry industry is widely held to be resource intensive, with high environmental impact. The concern is higher for ferrous foundries employing sand casting processes. Emissions in foundries have been identified, investigated and documented by various environmental protection agencies as well as by researchers. This includes emissions to air and water, and solid waste. Figure 1 shows material and energy inputs and outputs in various stages of sand casting process (Dalquist, 2004). The melting process requires approximately 55% of the total energy and emits the maximum amount of hazardous air pollutants (HAPs) and particulate matter (PM). The energy consumption and emissions in mould-making, core-making, melting (with cupola, electric arc, induction, reverberatory, open hearth and fuel-fired furnace), refining, pouring, cooling, cleaning and finishing operations of sand casting as well as investment casting, lost-foam casting and die-casting have been documented in energy and environmental profile of the US metal casting industry (US Department of Energy, 1999). A comprehensive list of criteria and toxic pollutant emission factors, for sources commonly found in iron foundries, is provided by the Environmental Protection Agency, USA (EPA-USA, 1990). The environment impact of casting and its sub-processes have also been presented in Emission Estimation Technique Manual (Queensland Department of Environment, 1999), and Emission Calculation Fact Sheet (Michigan Department of Environmental Quality, 2004). The emissions are traditionally evaluated and compared by the amount of various pollutants emitted per ton of melt. Each emission has a different impact on the environment, and it is necessary to quantitatively evaluate the potential impact (damage) to human health and ecology at local, regional and global level. The impact of a product on environment during its entire life (raw material extraction, manufacture, transportation, usage and disposal) can be evaluated by Life Cycle Assessment (LCA). Various categories of impact include global warming, acidification, eutrophication, human toxicity and eco-toxicity. Life Cycle Assessment involves assessing all the inputs and outputs of a product or process; assessing the associated wastes, impact on human health and ecological burdens; and interpreting the results of the assessment. The basic steps of LCA methods include: (1) generation of life cycle inventory (LCI) data, (2) characterization of LCI data to compute the effect of a particular LCI data item with respect to a characterization factor identified for that LCI, (3) impact assessment corresponding to the LCI data item by grouping it into various impact categories, and (4) normalization by comparing the results with a reference to get a common unit for measuring the impact load. A commonly used reference is the total environment load of that country divided by the number of inhabitants. The evaluation is aggregated in a common unit such as Person Equivalent (PE) and disabled adjusted life years (DALY). Some methods also allow assigning weights (as per the politically determined target for that region) to the normalized scores of impact categories, and calculating the weighted score.

Fig. 1 Material and energy flow in sand casting process (Dalquist, 2004). LIFE CYCLE ASSESSMENT METHODS The most common LCA methods include ISO 14040-1997, EDIP-1997 (Environmental Design of Industrial Products) and Eco-Indicator 99. The International Standards Organization (ISO) in 1997 released the ISO 14040 standard for life cycle assessment (EPA USA, 2001). The EDIP (Environmental Design of Industrial Product) method has been developed by Danish Environmental Protection Agency and Technical University of Denmark in 1996 (Danish EPA, 2004). These t methods involve evaluation of emissions into various impact categories. The impact categories as per ISO 14040 are global warming, acidification, eutrophication, human toxicity, ecological toxicity, ozone depletion, and resource depletion. The impact categories as per EDIP are global warming, acidification, eutrophication, human-toxicity, eco-toxicity, persistent-toxicity, ozone depletion, bulk waste, slag and ashes, hazardous waste, radioactive waste and resources. Theses impacts are further normalized and aggregated into a common unit referred as Person Equivalents (PE). Eco-Indicator 99 uses the damage-oriented approach. It involves computing (a) damage to human health, expressed as the number of year life lost and the number of years lived disabled, expressed as disability adjusted life years (DALY), (b) damage to ecosystem quality, expressed as the loss of species over a certain area during a certain time, and (c) damage to resources, expressed as the surplus energy needed for future extraction of minerals and fossil fuels. These three damages can be combined to get the total score of environmental impact (Pre Consultants, 2002). All the above methods use average values of environmental impacts in various categories for manufacturing processes. This is useful for comparing various casting processes (for example, sand casting, investment casting, and pressure die casting) as a whole. The methods do not permit selection and comparative evaluation of different options for materials and sub-processes (for example, selection of cast metal, melting furnace, and molding/core making process). Such an evaluation at the product and process design stage can help in choosing the most environmental friendly metal-process combination. Design for Environment (DFE), which involves early prediction of the environment impact of a product and taking suitable steps to minimize the impact by selecting more environment-friendly material and processes. The application of LCA for DFE for various products and processes has been reported in literature. For example, using the EDIP LCA method for washing machine, it was concluded that the use of natural gas for heating of water instead of electricity could reduce the

molten metal Metal

preparation

metal (scrap), alloys, flux

Finishing

PM, NOx HC,CO,

SO2

acidic wastewater

PM

PM, CO, VOC,HAP,

NOx

wastewater with solvents, oils

metals extraction

cleaning solvents

scrap metal, abrasives

ProductInput Vapor waste Aqueous waste solid waste Included in analysis Not included in analysis

slag, dross,spent, RM

cooling water

cooling water

Casting

cast metal

energy

Energy

energy

Mold preparation

waste sand

sand collection

sand, binders energy

environmental impacts by a factor of two or more in all impact categories except hazardous waste (Nielsen, 1999). A study of Xerox photocopiers in Australia reported that remanufacturing could reduce the resource consumption and waste generation by a factor of three (Kerr, 2001). Environmental impacts as global warming, acidification, photochemical smog and nutrient enrichment were found to be lower for copper recovery from printed circuit board (PCB) as compared to the primary source of copper extraction (Legarth, 1995). Hot dip galvanizing when compared with low VOC (volatile organic compound) paint and standard paint produces lower global warming potential, acidification potential and photo-chemical ozone creation potential (Cook, 2004). Campo (2003) developed ‘DFE Workbench’ that performed analysis, synthesis, evaluation and improvement of products’ life cycle features during the modeling of the product helping the designers to evaluate the environmental impacts of the product at the design stage. A few researchers have reported the application of LCA methodology in metal casting domain. Backhouse et al (2004) compared the environmental implications of replacing a ferrous component with an aluminum component for an automobile casting, using the Boustead model compatible with ISO 14040 (1997). It was revealed that though energy consumption and global warming potential (GWP) are higher for aluminum during the production stage, the resulting lighter vehicle will reduce the fuel consumption and result in lower GWP after 250,000 km of use. In the event of 50% use of secondary material, aluminum results in lower GWP after 150,000 km of use. Dalquist (2004) suggested environmentally benign design parameters such as minimizing the need for cores, and substituting it by increased machining for core-produced cavities. Where cores are still needed, the environmentally conscious designer should move away from hot box processes, whose high temperature curing requires significant energy and produces hazardous air pollutants (HAPs). Instead, no-bake processes are suggested as a more environment-friendly alternative. They expressed an immediate need for applying Life Cycle Assessment (LCA) tools to conventional manufacturing processes including casting. The goal of this work is to evolve a methodology for assessing the environmental impact of casting material and process plan to facilitate environment-friendly casting product-process design. This involves evaluation and comparison of various emissions to air, water and solid emitted during various steps in casting process. The focus is on air pollutants and particulate matter emitted during sand casting of ferrous alloys, mainly grey cast iron and cast steel. METHODOLOGY The methodology for evaluation and comparison of environmental impacts of sand casting process comprises three steps – generation of LCI data, inventory characterization and impact assessment and evaluation. The overall framework is shown in figure 2, and described in detail here. GENERATION OF LCI DATA Emission data as per cast material and process for their various sub-processes of melting, molding, core making, pouring and cooling and finishing needs to be collected for specified functional units. These functional units are gms per ton of molten metal in case of emissions pertaining to melting, gms per ton of green sand for emission related to molding and gms per ton of core sand for emissions related to core making. Also for the selected impact categories of the LCA methodologies (ISO 14040, Eco-Indicator 99 and EDIP) inventory characterization, normalization and weighting factors needs to be compiled. The next step it to create the LCI table or process inventory table for a given combination of casting method, cast material and its sub-processes. This is performed by multiplying the emission factors with the weight of molten metal for emission related to melting, and similarly for emissions related with mold making and core making. INVENTORY CHARACTERIZATION Emission data from an LCI table is multiplied with its respective characterization factor to compute the quantitative impact of a particular life cycle inventory item. This is done for all items in LCI data. For example cupola emissions: sulfur dioxide and nitrogen dioxide, cause acidification. The acidification potential of sulfur dioxide is considered as reference one and others are factors in accordance to their impact on acidification as per LCA methodology. A sample calculation of acidification potential (AP) is given below.

Acidification Potential (AP) = ∑=

n

iii eAPwn

1..

Where n = number of parts in the batch; w = molten metal required in tons per part; iAP = acidification factor for inventory i

ie = emission value for inventory i. Acidification calculation for melting with cupola for gray cast iron (GCI) casting

Emission Emission value gms/ton Acidification factor AP for an inventory SO2 600.00 1.00 600.00 NO2 45.30 0.71 32.16

Total acidification potential for one ton of melt is 632.16 (as per ISO 14040) IMPACT ASSESSMENT AND EVALUATION The potential impact values of all LCI data are then grouped into respective categories as per LCA methodology. This grouping is done for all sub-processes, and total environment damage (impact) under each impact category is calculated. These characterization tables are constructed for all impact categories of the selected LCA methodology. Impact assessment under each impact category is displayed in tabular and graphical representations. These impact assessment values can be normalized to get a single value for all impacts categories represented as PE (personal equivalent). The score of individual impacts is multiplied by the normalization factors (as per LCA) and then added to get the total PE score. The impact assessment values under each category and the PE score can be used for comparison of various process combinations and product designs along with the impact assessment values under various categories.

Fig. 2 Framework for evaluation and comparison of environmental impact.

Select the casting sub-process for melting, mold and core making, pouring and cooling

and finishing

ISO 14040 EDIP

Eco-Indicator 99

Select cast material and process

Calculate emissions as per molten metal, sand and core requirement

Generate Life Cycle Inventory data

Select LCA methodology

Inventory characterization

Database of emissions

Emission documentation

Impact assessment View results

Save current project Comparison of process

combinations and products

Previous project

Interpretation

Database of projects

PROGRAM IMPLEMENTATION The quantitative evaluation of environmental impacts of sand casting using the above-mentioned methodology is implemented in a web-based software program employing eXtensible Markup Language (XML) for back end database and Java Server Pages (JSP) for front-end programming. All HAPs and PM for gray cast iron and steel are considered in the program. Appendix I gives the list of emissions for gray cast iron and cast steel (compiled from EPA-USA, 1990, US Department of Energy, 1999, Queensland Department of Environment, 1999, and Michigan Department of Environmental Quality, 2004) along-with their impact categories as per LCA methods. Three LCA methods ISO 14040, Eco-Indicator 99 and EDIP are considered. Table 1 presents the impact categories used in the program for the three LCA methods. Appendix II gives the characterization factors of emissions as per their impact categories (compiled from, Pre Consultants, 2002, and EPA-USA, 2001). The emission data is structured as per the method, material and sub-processes, and stored in XML format. The XML is a self-describing data mark up language, and has been used to enable a modular and systematic approach to casting emission data management and to facilitate quick searching and identification of any desired item of information. The XML structure comprises of a tree and several data blocks. The XML tree represents the hierarchal (parent-child-grandchild) relationship between different data blocks, represented by nodes. The sample XML tree (fig. 3) shows the child nodes for the cupola process node. The program multiplies the emissions data with the characterization factor to compute the quantitative impact of a particular life cycle inventory item, and repeats this for all items of LCI data. The impacts of individual LCI data are then grouped into impact categories as per LCA methods and then combined to calculate the impacts of all sub-processes for an impact categories this is done for all impact categories of the chosen LCA method. Further normalization can be performed to measure the impacts in terms of person equivalent (PE). Each casting is evaluated as a project and all information generated is saved in XML format (fig. 3) for future reference and comparison. The program developed allows process selection that includes various sub-processes of casting. The various sub-processes included in the program are presented in table 2.

Fig. 3 Emission and process data structure in XML.

Table 1. Impact categories used in the system with the major source of information.

LCA method Impact Categories considered Source

ISO 14040 Global warming, Acidification, Photo-chemical smog Eutrophication, Human toxicity, Ecological toxicity EPA-USA 2001

Eco-Indicator 99

Carcinogens, Respirated organics, Respirated inorganics, Climate change, Acidification /Eutrophication, Eco toxicity, Ozone layer, Radiation

Simapro® demo version

EDIP Global warming, Acidification, Photo chemical smog, Eutrophication, Human toxicity, Eco-toxicity

Simapro® demo version

Table 2. Sub-process selection options and other inputs to the system.

Input Options Number of parts to be cast Molten metal required per part (in tons) Mold sand required per part (in tons) Core sand required per part (in tons) Material Gray Cast Iron and Cast Steel

Melting process Cupola, Cupola-scrubber, Electric arc furnace, Electric induction, Open hearth and Reverberatory furnace

Mold Making Process Green sand mould and Sodium silicate mold

Core Making Process Shell cores, Phenolic No-bake, Phenolic urethane, Phenolic hotbox, Core-oil, Alkyd isocyanate, Low nitrogen furan, Nitrogen furan TSA catalyst, Furan hotbox.

Pouring and Cooling Process Pouring and cooling Finishing Process Cast finishing operations, Grinding LCA Method ISO 14040, EDIP, and Eco Indicator 99

CASE STUDY Employing the above methodology and program, a case study for evaluating the environmental impact of a sample sand cast part– a bracket shown in figure 4 is presented. This is followed by a comparison of (1) melting processes using different furnaces, (2) uncontrolled cupola and cupola with scrubber, (3) gray cast iron and cast steel, and (4) different core making processes. This is carried out under various impact categories for the three LCA methods, yielding PE (EDIP) and DALY (Eco-Indicator 99) scores. BRACKET CASTING

Material Gray Cast Iron Volume per casting 490867mm3 Casting layout 4 cavities per mould Mould box size 400X300X(100+100) mm Casting yield 62% Metal to Sand ratio 1:1.33 Metal weight 25.00 kg (4 castings and methoding) Batch size 160 castings (40 X 4) Total metal weight 1000 kg Total sand weight 1333 kg Total core weight 880kg Binder % 7% Melting furnace Cupola un-controlled Core making No bake phenolic Mold making Green sand

Fig. 4 A sample case study: Bracket casting.

The input screen of the program is given in figure 5. Figure 6 presents the LCI for one ton of bracket casting. Figure 7 presents the impact assessment as per the impact categories of ISO14040. Melting with cupola contributes heavily to the environmental impacts: global warming, human toxicity, photochemical smog and acidification potential. High global warming potential is because of high CO2 emission (309.39 kg/ton). Human toxicity is due to lead and NH3 emissions. Both carcinogens (cancer) and non-carcinogens toxicity is considered in human toxicity. Photochemical smog is due to considerable amount of CO. Acidification is due to the presence of emissions as SO2, NO2 and NH3. Pouring and cooling results in ecological toxicity due to Benzene, Formaldehyde and Toluene emissions. Graphical representation of impact assessment is shown in figure 8. Environmental impacts of molding and core making are found to be negligible as compared to melting. Impact assessment of the above bracket casting is also evaluated using EDIP and Eco-Indicator 99. Employing EDIP impact assessment to global warming (455537.3), acidification (643.97), photo Chemical Smog (2262.93), eutrophication (67.28), human toxicity (3.02E10), eco toxicity (109005.87) has been computed. HAPs cause eco-toxicity soil chronic, eco-toxicity water chronic and eco-toxicity water acute. These have been added to get the eco-toxicity (total) value. Similarly, HAPs cause human toxicity air, soil and water. All these three categories have been added to get the human toxicity (total) value.

Employing Eco-Indicator 99 impact assessment carcinogens (3.77E-5), respirated organics (1.41E-4), respirated in-organics (1.84), climate change (0.08), acidification /eutrophication (918.80) and eco toxicity(108659.82) has been computed. Differences in the values of assessment of same impact category but different LCA methods exist primarily due to different assignment of emissions to impact categories and different characterization factors for the emissions. Cupola emissions cause high global warming potential, acidification, photo chemical smog and toxicity. These were confirmed by the three LCA methodologies.

Fig. 5 Input screen of the program.

Fig. 6 LCI inventory of bracket casting.

Emissions during casting (pouring and cooling) also result in environment impact as human toxicity, ecological toxicity, photochemical smog and acidification. The impact is however, much lower compared to cupola melting. Environmental impacts of mould making, core making and cast finishing are even lower. The PE (normalized) value as per EDIP is 5.1 and the PE value after considering the weighting is 13.47. The DALY score as per Eco-Indicator 99 is 1.9. These values can be considered as the sum total impact of all emissions for producing 160 bracket castings (total 1 ton of poured metal).

Fig. 7 Impact assessment of bracket casting using ISO 14040

Fig. 8 Graphical representation of impact assessment of bracket casting using ISO 14040.

COMPARISION OF MELTING PROCESSES As evident from the previous section, melting dominates the environmental impacts of casting, in this section we present the comparison of melting with cupola, electric arc furnace, electric induction furnace and reverberatory furnace, for one ton of gray cast iron melting. The comparison using ISO 14040 illustrates that cupola melting causes the highest global warming potential (due to high CO2 emission) and highest human toxicity (due to lead emission). Electric arc furnace causes highest acidification potential (due to high SO2 and NO2 emissions). Evaluation of melting furnaces using EDIP also confirmed the above comparisons (figure 9). The reverberatory furnace causes acidification, human toxicity and eutrophication as per ISO 14040 and global warming potential, acidification, eutrophication and human toxicity as per EDIP. Use of Eco-Indicator 99 for the above comparison revealed that reverberatory furnaces cause the highest acidification and eutrophication potential due to higher characterization factor for NO2. The characterization factor for NO2 is 5.71 in Eco-Indicator as compared to 0.71 in EDIP and ISO14040. Considerable acidification/eutrophication potential impact is observed for melting with electric arc furnace, while melting with cupola causes the highest eco toxicity due to lead emissions.

Fig. 9 Comparison of environmental impact of melting furnaces.

ISO 14040

3094

631

5110

6

3533

0 0 602

208 0 0 0 0 0 0370

0 3

1841

0 342 0

5320

516

0 1000 2000 3000 4000 5000 6000

Global Warming X 100

Acidification PhotoChemical Smog

Eutrophication Human Toxicity E5 Ecological Toxicity

Cupola Electric-Arc Electric-inductionReverberatory

EDIP

4408

598

2003

61

2995

3

5320

26152160

8 0 0 0 0 0 271 0

2940 1841

27

3547

0

1721

378 0

1000 2000 3000 4000 5000

Global WarmingX100

Acidification PhotoChemical Smog

Eutrophication Human Toxicity X E7

Ecotoxicity

Cupola Electric-Arc Electric-inductionReverbatory

Eco indicator 99

0 0 2 0 8

107

0 0 0 0 0 0 0 0 0 0 0 0 0 09

0 00 0 0 013

0 0

135150

0 20 40 60 80

100 120 140 160

Carcinogens Respirated organics

Respirated inorganics

Climatechange

AcidificationX 100

Eco toxicityX1000

Radiation Ozone layer

Cupola Electric-Arc Electric-inductionReverberatory

Table 3. PE and DALY scores for melting processes.

FURNACE / PE, DALY Cupola Electric Arc Electric Induction Reverberatory PE (EDIP) 8.468 0.082 0.756 0.079

DALY (Eco- Indicator 99) 1.646 0.262 0.064 0.200

On comparing the PE scores cupola melting is found to be eight times more impacting than any other furnace. Reverberatory and electric induction furnace are more damaging as compared to electric arc furnace primarily due to high characterization factor of lead (1.1E8) that causes human toxicity and because lead emissions are not reported for electric arc furnace. DALY scores also confirm cupola to be the most environmental impacting melting process followed by electric arc, reverberatory and induction furnace (Table 3). EVALUATION OF EMISSION CONTROL TECHNOLOGY – CUPOLA SCRUBBER Various control technologies are used in melting for reducing the emissions. In this section evaluation of the effectiveness of cupola scrubber is presented. Figure 10 presents the effect of cupola scrubber on various impact categories. It is observed that global warming potential and human toxicity reduces to zero and 50% reduction in acidification is possible by the use of cupola scrubber as per ISO14040. Using EDIP 67% reduction is observed in global warming, as CO is not controlled by scrubber but considered under EDIP for global warming. Reduction in acidification and human toxicity are similar to ISO 14040. Both ISO14040 and EDIP confirm that scrubber does not control the emissions causing photochemical smog. Eco-Indicator 99 reveals the possibility of 100% reduction in eco toxicity and 65% reduction in acidification/eutrophication. The PE score as per EDIP for cupola uncontrolled is 8.46, and cupola with scrubber is 0.138, indicating 60 times reduction in impacts. The DALY score reduces from 1.642 to 0.162 indicating ten times reduction in environmental impacts on application of scrubber.

Fig. 10 Comparison of uncontrolled cupola and cupola with scrubber.

Eco indicator 99

0 2 0

883

1070 0 0 0 0 0

312

0 0 0 0 0

100 200 300 400 500 600 700 800

Carcinogens Respirated organics

Respiratedinorganics Climate

changeAcidification Eco toxicity

X1000Radiation Ozone layer

Cupola Cupola-scrubber

ISO 14040

3094

631

3533

0 0 0 0 0

5110

6

5110

300 0

1500 3000 4500

Global Warming X 100

Acidification PhotoChemicalSmog

Eutrophication Human Toxicity E5 Ecological Toxicity

Cupola Cupola-scrubber

EDIP4408

61

2995

3

1460 2003

0 6 0 598

2003

300 0

1000 2000 3000 4000

Global WarmingX100

Acidification PhotoChemicalSmog

Eutrophication Human Toxicity XE7

Ecotoxicity

Cupola Cupola-scrubber

COMPARISION OF GRAY CAST IRON AND CAST STEEL Eco-friendliness of gray cast iron with cast steel is compared in this section with melting using electric arc furnace. The evaluation of impacts using ISO14040 show that gray cast iron melting cause higher or equal impact on all categories except acidification. Using EDIP, it is observed that gray cast iron melting causes higher or equal impact on all categories except acidification and human toxicity. Cast steel causes four times more impact on acidification as compared to gray cast iron (SO2 and NO2 emissions) and gray cast iron causes 17 times more impact on eutrophication as confirmed by both ISO14040 and EDIP. The Eco-Indicator 99 confirms higher (40%) acidification / eutrophication for cast steel and equal impact on eco toxicity (figure 11). The PE values are lower for gray cast iron (1.20) as compared to cast steel (1.31). The DALY score of cast steel is 1.6 as compared to gray cast iron score of 0.6, because of higher acidification potential of cast steel pollutants.

Fig. 11 Comparison of gray cast iron and cast steel.

COMPARISION OF CORE MAKING PROCESSES As compared to melting core making processes appear to have negligible impacts on environment in this section comparison of various core making processes is presented primarily, to rate the various processes for eco-friendliness. To facilitate comparison, the impacts are multiplied by a factor of 100 (or higher). As per ISO 14040, Hot box furan causes the highest acidification and eutrophication (due to higher emission of NH3, NO2 and SO2). No bake phenolic (due to Benzene), Alkyd isocyanate (due to Benzene, Formaldehyde and Toluene) and shell (due to Benzene, Formaldehyde, Toluene and Xylene)

Eco indicator 99

13548

1571

23160

1570 0

5000

10000

15000

20000

Acidification /Eutrophication Eco toxicity

Gray cast iron

Cast steel

ISO 14040

0

5332 836 209 404 0

21792

809 12 40427 27 0

5000

10000

15000

20000

Global Warming Acidification Photo ChemicalSmog

Eutrophication Human Toxicity X E3

Ecological Toxicity

Gray cast iron Cast steel

EDIP

173

5332

3312166

288 192 1

21792

303 128 563 1900

5000

10000

15000

20000

Global Warming X100

Acidification PhotoChemicalSmog

Eutrophication Human Toxicity X E5

Ecotoxicity

Gray cast iron

Cast steel

cause higher ecological toxicity impact as compared to other core making processes. Nitrogen furan TSA and shell process cause higher photochemical smog (due to Toluene and Benzene emission) as compared to other processes. As per EDIP, the hot box furan causes the highest acidification and eutrophication (due to higher emission of NH3, NO2 and SO2). Global warming is highest for no bake phenolic (due to CO emission). Human toxicity is the highest for no bake phenolic followed by shell, urethane phenolic and alkyd isocyanate. Eco toxicity is the highest for shell followed by hot box furan process. As per Eco-Indicator 99 respirated inorganics and acidification/eutrophication is the highest for hot box furan (due to NH3, NO2 and SO2). Eco-toxicity is highest for no bake phenolic followed by urethane phenolic and shell process (due to Benzene, Phenol and Toluene emissions). All the three LCA methods confirm that among the various furan core making processes, nitrogen furan appears to be the cleanest core making process, and core oil process appears to be the cleanest process of all the nine core making processes (figure 12). The PE and DALY score reveal that shell, hot box furan and no bake phenolic are among the top three most impacting core making processes, and core oil and nitrogen furan are among the least impacting processes (Table 4).

ISO 14040

206

3

288

3

157

5 9 75

509

217

221

30 72 175

48

518

110 0 50 0 19 1 0 2 88152

73 14 32 90 72 9 6 9

2263

1142

219 53

0

1518

1525

364 55

9

113

322

0

500

1000

1500

2000

2500

Nobake-phenolic

Urethane-phenolic

Hotbox-Phenolic

Coreoil Shell Alkyd-isocyanate

Nitrogen-furan

Nitrogen-furan-TSA

Hotbox-furan

Acidification X E-4Photo Chemical Smog X E-4Eutrophication X E-4Human Toxicity X E-4Ecological Toxicity X E-4

EDIP

517

381

60 142

486

545

163

394

27243

5 285

5 158

5 20 87 505

3 39 589

6 548

14 14 36

1,08

5

232

117

21 50 143

111

18 11 1258

1,35

3

1,51

1

122

13,4

26

246

483

789

4,42

7

0

2000

4000

6000

8000

10000

12000

Nobake-phenolic

Urethane-phenolic

Hotbox-Phenolic

Coreoil Shell Alkyd-isocyanate

Nitrogen-furan

Nitrogen-furan-TSA

Hotbox-furan

Global Warming X E-4Acidification XE-4

Eutrophication X E-4Human Toxicity X1000

Ecotoxicity X E-2

Eco indicator 99

240

115

21 5 143

114

14 10 11110

152

19 40 175

250

98 167

6

8012

90

7584

88

4538

52 349

2713

224

22

2356

16

941

36 18 140

4164

7429

7039

366

103

4429

200

44 183

2913

585

0

2000

4000

6000

8000

10000

12000

Nobake-phenolic

Urethane-phenolic

Hotbox-Phenolic

Coreoil Shell Alkyd-isocyanate

Nitrogen-furan

Nitrogen-furan-TSA

Hotbox-furan

Carcinogens X E-11Respirated organics X E-11Respirated inorganics X E-10Acidification XE-5Eco toxicity X E-4

Fig. 12 Comparison of core making processes.

Table 4. PE and DALY scores for core making processes.

Core making process Nobake-phenolic Urethane-phenolic Hotbox-Phenolic Coreoil Shell

PE value X E4 39.769 27.469 13.222 1.795 109.625 DALY score X E8 83.618 3.697 76.248 1.794 48.566

Core making process Alkyd-isocyanate Nitrogen-furan Hotbox-furan Nitrogen furan TSA PE value X E4 20.241 5.392 30.334 6.635

DALY score X E8 4.171 4.609 136.030 28.895 CONCLUSION In this work, a methodology for evaluating and comparing different casting process plans has been developed and implemented in a web based program. The methodology presently considers all major air pollutants for various sub-processes of sand casting of ferrous alloys. Using the program, the environmental impact for a given product design can be quantified. Various impact values including PE and DALY scores can be used to compare alternative combinations of product designs and process plans. The melting operation was found to generate the highest emissions, dominating the total impact on environment, as confirmed by all three LCA methods. The selection of cast material and type of melting process thus has considerable potential in reducing the environmental impacts. In particular, electric arc and induction furnaces are found to be eco-friendly. Gray cast iron is found to result in lower environmental impacts as compared to cast steel while melting with electric arc furnace. Of the various core making methods, the oil cores prove to be the most eco-friendly. These conclusions are based on currently available data from various sources, and there may be some difference in results for specific foundries. The conclusions also differ based on the LCA method used, owing to differences in impact categories, inventory assignment to impact categories, and varying characterization factors. Overall, the methodology and the program enable comparative evaluation of different product-process designs in a quantitative manner. The use of Internet technology allows collaboration between designers, foundry engineers and environment specialists for arriving at the best solution for meeting the environmental objectives. The methodology and program can be easily expanded to consider liquid as well as solid emissions, and extended to other cast materials and processes. REFERENCES Backhouse, C. J., Clegg, A.J., Staikos, T., Reducing the environmental impacts of metal castings through life-cycle

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(FRED): Using Life Cycle Assessment to Evaluate Preferability of Products, http://lcacenter.org/pdf/fred.pdf (Oct. 2001) Kerr, W., and Ryan C., 2001, Eco-efficiency gains from remanufacturing A case study of photocopier remanufacturing at

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http://ieeexplore.ieee.org/iel3/3945/11421/00514963.pdf?isnumber=&arnumber=514963 (1995) Michigan Department of Environmental Quality- Environmental Science and Services Division, FACT SHEET #9841 (Rev.

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APPENDIX I: EMISSION DATA FOR FERROUS FOUNDRIES

TABLE A. EMISSIONS OF MELTING AND FINISHING OPERATIONS FOR GRAY IRON FOUNDRIES.

All emissions are in g (emission) /ton (of melt)

TABLE B. EMISSIONS OF MELTING AND FINISHING OPERATIONS FOR STEEL FOUNDRIES.

Name of Process / Name of Emission

Open hearth furnace

Open hearth oxygen lance

Electric arc furnace

Electric induction Grinding Castfinish

Particular matter 4983 8380 5889 45.3 770.1 2.03 Sulfur dioxide 0 0 108.72 0 0 21608.1 Nitrogen dioxide 4.53 0 90.6 0 0 0 VOC 77.01 77 158.55 0 0 498.3 Carbon monoxide 0 0 0 0 0 0

All emissions are in g (emission) /ton (of melt)

TABLE C. EMISSIONS OF MOLD MAKING, CORE MAKING, POURING, AND COOLING.

Name of Process / Name of Emission

Sodium silicate Green Sand Nobake

phenolic Urethane phenolic

Hotbox phenolic Core oil Shell

Ammonia 0.038 0.065 0.039 0.083 10.931 0.038 3.86 Hydrogen sulfide 0.197 0.832 1.462 0.057 0.009 0.057 0.094 Nitrogen oxides 0.028 0.562 0.029 0.044 0.638 0.081 0.994 Sulfur dioxide 0.244 0.253 15.107 0.061 0.036 0.115 3.509 Benzene 1.41 0.611 11.209 5.351 1.002 2.344 6.667 Formaldehyde 0.169 0.004 0.01 0.022 0.006 0.098 0.035 Hydrogen cyanide 0.179 0.118 0.029 1.053 1.184 0.086 10.526 M-xylene 0.094 0.021 0.097 0.439 0.121 0.239 0.585 Naphthalene 0.005 0.021 0.049 0.022 0.03 0.048 0.058 O-xylene 0.094 0.021 0.049 0.132 0.03 0.287 0.117 Phenol 0.273 0.131 0.975 3.904 0.203 0.057 2.456 Toluene 0.282 0.063 0.694 0.833 0.182 0.478 2.907 Total aromatic amines 0.094 0.021 0.049 0.351 1.275 0.096 2.939 Particular matter 0 0 0 0 0 0 0 Nitrogen dioxide 0 0 0 0 0 0 0 Carbon monoxide 0 0 0 0 0 0 0 Lead 0 0 0 0 0 0 0

Emissions are in g (emission) /ton (of mold /core sand) for mold and core making and in g (emission) /ton (of melt) for pouring and cooling

Name of Process / Name of Emission Cupola Cupola-

scrubber Electric arc

furnace Elect. Ind. furnace

Reverberatory furnace Castfinish Grinding

Particular matter 19161.9 1600 1200 797.28 1721.4 2.04 8471.1 Sulfur dioxide 600 300 4200 0 2 0 0 Nitrogen dioxide 45.31 0 1600 0 2627.4 0 0 VOC 81.54 0 81.54 0 67.95 0 0 Carbon monoxide 73000 73000 8607 0 0 0 0 Lead 271.8 0 0 24.68 34.4 0 0 Carbon dioxide 309399 0 0 0 294000 0 0

TABLE C. EMISSIONS OF MOLD MAKING, CORE MAKING, POURING, AND COOLING (continued).

Name of Process / Name of Emission

Alkyd isocyanate

Nitrogen furan

Nitrogen furan TSA Hotbox furan Pouring &

Cooling(GCI) Pouring &

Cooling(CS)

Ammonia 0.037 0.04 0.202 19.579 0 0 Hydrogen sulfide 0.007 0.405 0.485 0.06 0 0 Nitrogen oxides 0.355 0.012 0.372 0.411 0 0 Sulfur dioxide 0.04 0.607 4.858 0.088 9.06 9.06* Benzene 5.336 0.648 0.4534 0.537 23.9 23.9* Formaldehyde 0.106 0.257 0.065 0.009 0 0 Hydrogen cyanide 0.175 0.368 0.607 3.474 0 0 M-xylene 2.522 2.227 0.243 0.032 3.075 3.075* Naphthalene 0.037 0.04 0.04 0.032 2.95 2.95* O-xylene 3.838 0.729 0.04 0.032 1.175 1.175* Phenol 0.11 0.024 0.101 0.016 11.25 11.25* Toluene 1.535 0.121 8.825 0.032 10.45 10.45 Total aromatic amines 0.037 0.081 0.364 3.032 0 0 Particular matter 0 0 0 0 3469.98 3805.2 Nitrogen dioxide 0 0 0 0 4.53 4.53 VOC 0 0 0 0 63.42 63.42 Lead 0 0 0 0 0.185 0.185*

*assumed equal to GCI; GCI – Grey Cast Iron; CS – Cast Steel

TABLE D. EMISSIONS AND THEIR IMPACT CATEGORIES AS PER ISO 14040, EDIP & ECO-INDICATOR-99.

ISO 14040 EDIP Eco-Indicator-99 Name of Pollutant GW AP PS EP HT ET GW AP PS EP HT ET CA RO RIO CC OL RA ET AE

CO2 CO NO2

Sulfur Dioxide

Benzene Formaldehyde Toluene Phenol VOC Ammonia

Lead PM Nox

HCN H2S M-Xylene O-Xylene

IMPACT CATEGORIES AS PER ISO 14040: Global warming (GW) , Acidification potential (AP) , Photo-chemical smog (PS) Eutrophication potential (AP), Human toxicity (HT) and Ecological toxicity (ET) IMPACT CATEGORIES AS PER EDIP: Global warming (GW), Acidification potential (AP), Photo chemical smog (PS), Eutrophication potential (EP), Human toxicity (HT), Eco toxicity (ET) IMPACT CATEGORIES AS PER Eco-Indicator 99: Carcinogens (CA), Respirated organics (RO), Respirated inorganics (RIO), Climate change (CC), Acidification / Eutrophication (AE), Eco toxicity (ET)

APPENDIX II: CHARACTERIZATION FACTORS

EDIP Characterization FactorsGlobal Warming CO2 1 CO 2 Benzene 3 Phenol 2 Toluene 3 Formaldehyde 3 M-xylene 3 O-xylene 3 Acidification SO2 1 NO2 0.7 Ammonia 1.88 Hydrogen Sulfide 1.88 Nitrogen oxides 0.7 Photo Chemical VOC 0.4Smog CO 0.03 Benzene 0.2 Toluene 0.6 Formaldehyde 0.4 M-Xylene 1 O-Xylene 0.7 Eutrophication NO2 1.35 Ammonia (NH4) 3.64 Nitrogen oxides 1.35 Hydrogen cyanide 2.38 Human toxicity Air Water Soil SO2 1.30E+03 0 0CO 8.30E+02 0 0Lead (Pb) 1.10E+08 53 8.30E-2Benzene 1.00E+07 2.3 14Phenol 1.40E+06 0 0Toluene 2.50E+03 4.00E-3 1.00E-3Formaldehyde 1.30E+07 2.20E-5 5.80E-3Hydrogen Sulfide 1.10E+06 8.10E-4 0.26Nitrogen oxides 8.60E+03 0 0Hydrogen cyanide 1.40E+05 1.50E-3 0.71M-Xylene 6.70E+03 1.10E-3 6.70E-5O-Xylene 6.70E+03 1.10E-3 6.70E-5Eco Toxicity WC SC WALead (Pb) 400 0.01 0Benzene 4 3.6 0Phenol 0 0 0Toluene 4 0.97 0Hydrogen cyanide 800 7.60E+03 0M-xylene 4 0.4 0O-xylene 4 0.4 0

ISO 14040Characterization Factors Global Warming CO2 1Acidification SO2 1 NO2 0.7 Ammonia 1.9 NOx 0.71 Photochemical CO 0.07 Smog Benzene 1 Phenol 1.86 Toluene 4.19 Formaldehyde 9.12 Eutrophication NO2 0.13 Ammonia 0.33 Nitrogen oxides 0.13 Human toxicity Lead (Pb) 15(Carcinogens) Benzene 1 Formaldehyde 0.003 Human toxicity Lead (Pb) 1,300,000(Non-Carcinogens) Ammonia 3.2 Benzene 17 Formaldehyde 7 Phenolics 0.045 Ecological Benzene 14.6Toxicity Formaldehyde 7.3 Toluene 3.7 M-xylene 3.7 O-xylene 3.7 Phenol* 3.1

* Phenol impact on aqueous medium

Eco indicator 99 Characterization FactorsCarcinogens Benzene 1.58E-06Respirated Benzene 4.50E-07 organics VOC 6.00E-7 Phenol 0.0000019 Toluene 1.27E-06 Formaldehyde 1.03E-06 M-xylene 2.22E-06 O-xylene 2.14E-06 Respirated Particular matter 8.03E-05inorganics SO2 3.90E-05 NO2 1.19E-06 Ammonia (NH4) 5.10E-05 Nitrogen oxides 1.19E-06 Climate Change CO2 2.00E-07 CO 3.06E-07 Acidification SO2 1.041 NO2 5.713 Ammonia (NH4) 15.57 Eco toxicity Lead (Pb) 394 Benzene 2.75E-02 Phenol 133 Toluene 2.40E-03 Radiation Lead (Pb) 1.30E-12

WC – Water chronic; SC – Soil chronic; WA – Water acute