Research on life cycle assessment of film-laminated steel packaging

Research Institute,Baoshan Iron & Steel Co.,Ltd.,Shanghai 201999,China

Abstract: The environmental issues associated with packaging materials have been attracting increasing attention.Life cycle assessment (LCA) is currently the main method used worldwide for evaluating green packaging materials.In this study,the LCA method was used to evaluate the environmental impact of Baosteel’s newly developed process for manufacturing film-laminated steel packaging materials,from raw material mining,production,and processing to their storage,consumption,recycling,and final disposal.The environmental performance and main influencing factors were analyzed and compared.In addition,the life cycle environmental characteristics of film-laminated steel cans,tin-plated steel cans,and aluminum cans were compared.Of the main environmental indicators of the life cycle of the film-laminated steel can,the environmental load of the substrate accounts for the largest proportion,followed by electricity.The environmental impact of the production of film materials cannot be ignored.The overall environmental performance of film-laminated steel cans is better than that of aluminum cans.

Key words: green packaging; life cycle assessment; film-laminated steel cans; tin-plated steel cans; aluminum cans

1 Introduction

The environmental problems associated with packaging materials have been attracting increasing attention,and the competition among various pack-aging materials is becoming increasingly fierce.Traditionally,when evaluating the environmental impact of packaging materials,concern has been focused on the environmental impact of the pack-aging after its disposal.In life cycle assessment (LCA),which is currently the main method used for evaluating green packaging materials[1-2],the consump-tion of resources and energy is quantified along with the environmental emissions generated during the entire product life cycle process;an evaluation is then made of the impact of the consumption and emissions on the Earth’s resources,the ecological environment,and human health.

The LCA method was first developed by the Midwest Resource Institute (MRI) in 1969 to assess the life cycle of the Coca-Cola beverage bottle.Cur-rently,LCA technology is widely used in many coun-tries and has become an important tool for environ-mental certification,new product development,and for avoiding trade barriers[3].

At present,the product design methods used by steel companies in China generally consider only the quality and cost factors,and rarely consider environmental impact or include only a qualitative analysis.As yet,product eco-design research remains at the conceptual stage,which is evident in the following respects:the lack of theoretical methods to ensure systematic operability,the lack of systematic eco-design models,and the lack of sufficient and reliable environmental impact data regarding product life cycle.

In this study,film-laminated steel is taken as an example for the investigation of product life cycle eco-design technology in the steel industry toward the development of a reliable and operable eco-design model and supporting database,and to investigate the application of the LCA method in ecological product design.

2 Research methods

2.1 Film-laminated product life cycle and research boundaries

Film-laminated steel is a packaging material recently developed by Baosteel.This film-laminated steel is a metallic material that combines the features of a polymer resin film and a metal plate,and thus exhibits excellent deep drawing capacity,abrasion resistance,corrosion resistance,and aesthetics as compared with those of traditional printed tinplates.

In this study,the environmental performance of a Coca-Cola 330-mL beverage can throughout its life cycle was taken as the research object.

The life cycle process of film-laminated steel cans served as an important basis for establishing a product LCA model as well as in ensuring clarity regarding the boundaries of the collected site data.This investigation comprised a full life cycle study of film-laminated steel cans as a cradle-to-grave LCA.The stages of the product life cycle can be summarized as follows:

(1) Upstream raw material production stage:mining or production of raw materials (such as iron ore),energy (such as coal),and auxiliary materials (such as various coatings);

(2) Transportation phase:off-site transportation of purchased raw materials and energy,and transportation of the film-laminated steel cans;

(3) Product production stage:production of the basilar plate,production of the biaxially oriented polyethylene terephthalate (BOPET) film material,and production and processing of the film-laminated steel can;

(4) Product use stage:use of the film-laminated steel can as a beverage package by the user;

(5) Disposal stage:recycling of the film-laminated steel cans.

Function unit definition:The function unit in LCA is a quantitative unit of the function of a product system,the main purpose of which is to standardize the input and output of the system to facilitate comparison of the environmental perform-ance data of a product.The LCA research method stipulates that a functional unit comprises 1 000 tanks (the “1 000 tanks” commonly used in pro-duction sites is a statistical analysis benchmark for the indicators).In this study,the function unit was 1 000 cans,which is a commonly used benchmark in the statistical analyses performed in factories.

Fig.1 shows the manufacturing process of film-laminated steel cans,and Fig.2 shows the BOPET production process.

2.2 Computational method used in life cycle inventory of film-laminated steel cans

Life cycle inventory data includes those related to resource consumption,energy consumption,air-pollution emissions,water-pollution emissions,and solid-waste emissions.

According to GB/T standard 30052-2013 “Life cycle assessment specification on steel products (Pro-duct category rules)”,the basic computational logic of the life cycle inventory is shown in Equation (1):

(1)

2.3 LCA computational and analysis tools for film-laminated steel cans

In this study,the BaosteelLCA 4.0 software (shown in Fig.3) developed by Baosteel was used to perform the computation and analysis tasks.This software provides a convenient modeling platform with which users can build a flow chart of the manufacturing process (as shown in Fig.4) and the data input by the user can be intelligently checked.The software has rich LCA functions that can be used for LCA research,product marketing and promotion,and for meeting policy and regulatory requirements.

This software system has two main modules:the project system and the basic data system.The basic data system primarily manages the basic information required for LCA computation and provides user func-tions such as querying,modifying,deleting,and add-ing information.The project system manages specific projects,including calling for appropriate basic information,providing input and maintaining processed data for users,performing model computations based on the basic and processed data input by users,and outputting LCA results and analysis.

The software in the LCA model developed by Baosteel is based on the Leontief inverse matrix,which is used to describe the material flow,energy flow,and environmental flow of each unit process of the life cycle,and thereby establishes the association of

each unit process in the overall life cycle.

Fig.4LCAmodeloffilm-laminatedsteelcansusingBaosteel-LCA4.0

3 Results and analysis

3.1 Life cycle inventory of film-laminated steel products

There are many environmental factors in a life cycle inventory.This study focuses on the key indicators outlined in the relevant national standards of the metallurgical industry.

Table 1 shows the distribution of environmental load at each stage of the life cycle.The material of the can body is film-laminated steel and that of the can lid is aluminum,and the respective weight ratio of the can lid and can body is about 1∶10.

The results listed in Table 1 indicate that the life cycle environmental load of film-laminated steel cans is the greatest in the manufacturing stages of the can body and can lid,accounting for more than 95%.The combined environmental load of the transportation,use,and recovery phases accounts for less than 5%.As the can-body material is steel and the can lid material is aluminum,the environmental loads of the can body and can lid are highly correlated with the environmen-tal performance of the steel and aluminum materials.

Table 1 Distribution of environmental load of film-laminated steel cans at each life cycle stage %

The can-body manufacturing stage accounts for most of the environmental load in the life cycle.This stage was further analyzed to obtain the composition of the life cycle environmental load of the film-laminated steel can body,the results of which are shown in Fig.5.

Of the main environmental indicators of the life cycle of film-laminated steel cans,the substrate accounts for the most energy consumption,CO2emissions,and NOxemissions.The electricity used to manufacture the cans contributes the most to SO2,dust,and COD emissions.The environmental impact of the production of BOPET film materials for film lamination cannot be ignored.From the perspective of the composition of the various environ-mental indicators,to improve the environmental performance of film-laminated steel cans,the most important step is to improve the environmental performance of the substrate,followed by that of electricity and BOPET film materials used in film lamination.

3.2 Comparison of LCA of film-laminated steel cans with LCAs of tin-plated and aluminum paint cans

To compare the environmental performance of different packaging materials,LCAs were also perfor-med on tin-plated and aluminum paint cans,for which the research boundary conditions were consis-tent with those used in the LCA of film-laminated steel (see Section 2.1).The production stages of tin-plated and aluminum paint cans include the tinplate and aluminum plate substrate production processes,paint production process,and beverage can production process.Actual production data was obtained from the manufacturing plant.The calculations were performed using the BaosteelLCA 4.0 software,and the background database was consistent.

Fig.6 shows a comparison of the environmental indicators of the different packaging materials.

The LCA results reveal that film-laminated steel cans are superior to both tin-plated and aluminum paint cans with respect to life cycle energy consump-tion,water consumption,CO2emissions,dust emissions,SO2emissions,NOxemissions,and COD emissions.As a substrate material,although alumi-num is much better than steel in terms of its lower weight,the energy consumption associated with the manufacturing of aluminum is 5-6 times higher than that of steel,and the corresponding environ-mental emissions are also higher than steel.There-fore,the life cycle results confirm that the overall environmental performance of steel cans is better than that of aluminum cans.

4 Conclusions

(1) The life cycle environmental load of the film-laminated steel can is mainly concentrated in the manufacturing stage of the can body and can lid.As the can-body material is steel and the can lid material is aluminum,the environmental load of the can body and can lid is highly correlated with the environmental performance of the steel and alumi-num materials.

(2) The environmental impact of the production of BOPET film materials for film lamination cannot be ignored.Among the main environmental indicators of the film-laminated steel can,the environmental load of the substrate accounts for the largest proportion,followed by electricity and BOPET film materials.

(3) The overall environmental performance of film-laminated steel cans is better than that of aluminum cans.

(4) The LCA method provides a comprehensive,objective,and quantitative approach for evaluating the environmental characteristics of the product.Combined with performance and cost analyses,this method provides strong support for the eco-design and development of new products.