Ichiro Daigo

The University of Tokyo | Todai · Faculty & Graduate School of Engineering

Sri Lanka is a top producer of premium quality concentrated latex (CL), which becomes a base material for dipped rubber products such as gloves and condoms. The processing of CL is resource-intensive, requiring significant amounts of energy, fuel, water, and chemicals. This process leads to various environmental issues such as wastewater pollution,...

Sri Lanka is a top producer of premium quality concentrated latex (CL), which becomes a base material for dipped rubber products such as gloves and condoms. The processing of CL is resource-intensive, requiring significant amounts of energy, fuel, water, and chemicals. This process leads to various environmental issues such as wastewater pollution,...

Raw rubber production is the sole foundation for the rubber product industry, rendering raw rubber to manufacture essential commodities to mankind, such as tires, condoms, surgical gloves, and so forth. Raw rubber production involves various stakeholders; however, literature focusing on the social impacts of the supply chains of raw rubber producti...

Raw rubber production is the sole foundation for the rubber product industry, rendering raw rubber to manufacture essential commodities to mankind such as tires, condoms, surgical gloves, and so forth. Raw rubber production involves various stakeholders; however, literature focusing on the social impacts of raw rubber production and its supply chai...

The design of an optimal system for recycling photovoltaic panels is a pressing issue. This study performed a prospective life cycle assessment using experimental and pilot data to reveal the effectiveness of the proposed technologies. The proposed technologies include aluminum frame separation; precise mechanical separation consisting of primary a...

Avoiding the contamination of tramp elements in steel requires the non-ferrous materials mixed in steel scrap to be identified. For this to be possible, the types of recovered steel scrap used in the finished product must be known. Since the thickness and diameter of steel are important sources of information for identifying the steel type, in this...

As one of the main human activities affecting the global nitrogen cycle, food production and consumption caused a series of environmental issues with nitrogen, especially in densely populated cities. To comprehensively quantify these issues of cities, Beijing's food system was chosen as a case to build a refined 18-node nitrogen metabolic network m...

Life cycle assessment (LCA) has been developed for evaluating the environmental impacts associated with a product through its life cycle. LCA is used in product environmental footprint programs. In carbon neutrality, greenhouse gas emissions associated with a product and an organization are of great interest, where methodologies and databases devel...

Selection of recycling approaches is one of the remaining issues in the life cycle assessment (LCA) and a critical factor for materials selection based on the LCA. While several recycling approaches and allocation methods have been proposed, the impact of the recycling effect determined by different allocation methods on materials selection has yet...

The accumulation of impurities in the recycling of steel impacts the quality of secondary steel. Understanding impurity levels is crucial in the context of the proliferation of circular economy policies, expected high recycling rates, and growth of scrap consumption. By assuming the accumulation of impurities to be equal worldwide, the understandin...

Raw rubber production is the foundation of natural rubber product industry. Despite the various social issues (e.g., substandard working conditions) reported in raw rubber production, literature focusing on social impacts has been limited. Although social life cycle assessment (SLCA) has been a popular tool to assess the social impacts of a product...

The functional roles and environmental effects of long-lived buildings, infrastructure, and durable goods can determine both the benefits to natural environment and a city's human residents. However, their overall lifecycle metabolic processes are complicated and previous studies mainly considered specific materials or products. Here, we provide a...

Light weighting by material substitution is a key to reducing GHG emissions during vehicle operation. The GHG benefits are a salient factor in selecting lightweight materials for vehicles. Although the literature has performed lightweight material selections using GHG benefits under product- and fleet-based life-cycle inventory (LCI) analyses, recy...

Material stocks in buildings, infrastructure, and durable products play multiple roles in environmental and socioeconomic systems throughout their life cycle. After half a century of exploration, the study of material stocks has led to the development of a knowledge system. However, an overall picture of the evolution of knowledge in this field is...

National accounts for material stocks and flows are reported regularly by an increasing number of countries to promote a sustainable use of our natural resources. In this research we build upon the work of Herman Daly and Donella Meadows and propose a framework that links material stocks and flows to a conceptual hierarchy of ends and means which a...

It is crucial to spread the products that reduce Greenhouse Gas （GHG） emissions to achieve the ambitious target towards the decarbonized society. Life Cycle Assessment （LCA） can support the obtaining of a market for such products by quantifying the avoided GHG emissions through the life cycle. At the same time, there are some additional points to b...

It has become crucial for industries to work towards decarbonizing processes throughout the value chains. The guidelines published by the Institute of Life Cycle Assessment, Japan （ILCAJ） in 2015, “Guidelines for Assessing the Contribution of Products to Avoided Greenhouse Gas Emissions”, provides a methodology to assess the reduction of greenhouse...

Contamination with tramp elements is a major concern in steel recycling. This study aimed to identify the influence of impurity elements on the major properties of carbon steel. The content of impurity elements in recycled steel was determined via elemental analysis of randomly sampled steel bars. Of the 23 impurity elements considered, 15 were fou...

In this study, we conducted trace element analysis using laser-ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) to quantitatively analyze the distribution of tramp elements and their coexistence states with other elements in recycled steel materials. The concentration distributions of Cu, Sn, Pb, Ag, and Au in a 455 µm × 270 µm reg...

Steel is a structural material which is widely used in the world. Approximately 1.7 billion tons of steel is reported to be produced annually. Though steel is highly recyclable, the recycling of steel may encounter a restriction caused by Cu contamination. Therefore to avoid the mixing of Cu, we need to identify sources of mixing. Meanwhile, the ch...

High properties of stainless steels can be achieved by adding alloying elements and/or by structure control through complex heat treatments. Evaluations of such processes have so far been made in terms of the carbon dioxide emissions emitted or the energy consumption, but less attention has been given to resource intensity and "hidden flows". Using...

The steel industry has been concerned with contamination by tramp elements during repeated recycling of carbon steel. Increase of Cu content has never been observed at least by monitoring EAF steel bars from the late 1980s. However, the increase may happen in future. To surely avoid the increase which leads to ineffective recycling, mechanisms of C...

Lifetime of products is one of the key parameters in LCA and MFA. Lifetime of products is generally regarded as the average of a distribution which is observed from lifetimes of a product group. The average may be different among definitions of distributions. In this article, we introduced six different types of the products’ lifetime distributions...

By using the balance equation between input, output, and net addition to stock, we developed a method to estimate the lifetime distributions for buildings by statistics and some parameters from former studies. Understandable lifetime distributions were obtained from 1987 to 2010 in the type of lifetime distributions for cohort demolished in each ye...

In order to establish a “stock-type” society as opposed to a “flow-type” society, the effects of resource consumption on the natural environment must be fully understood. The research fields of material flow and stock accounting offer systematic methods for that analysis. The material flow in Japan calculated by the Ministry of Environment covers i...

Many waste ceramic materials and glasses (CerG) such as glass, concrete, pottery, porcelain, brick, and tiles are landfilled because they have been recognized to be less conducive to recycling. In this study, to enhance the recyclability of ceramic materials and glasses, a linear model to minimize natural resource consumption of CerG materials prod...

Economic growth and sometimes the use of green technologies have been associated with a rapid rise in the use of metals and minerals. In today's globalized economy, natural resource consumption influences environmental impacts far removed from the place of consumption. Knowledge about the flow of substances is fundamental to reducing natural resour...

In this study, the Weibull parameters (shape parameter and mean lifetime) for lifetime distributions of electronic devices in Vietnam have been estimated based on the previous questionnaire researches by us. The mean lifetimes for four appliances were drastically decreased in seven years and lifetimes in Hanoi and Ho Chi Minh City were almost same,...

In this research, we analyzed electric furnace steel using the laser ablation inductively coupled plasma mass spectrometry (LA–ICP–MS) method with the objective of quantitatively evaluating the concentration distributions of tramp elements present in microdomains. Point analysis was carried out for nine microdomain locations (defined as Areas) meas...

Owing to the growing number of risk factors that can be triggered by natural and manmade disasters, management of disruption risks in supply chains has become increasingly significant. Since the market concentration of raw material suppliers is a determinant of the supply disruption risk, identification of raw materials vital in a supply chain and...

We introduce several new resilience metrics for quantifying the resilience of critical material supply chains to disruptions, and validate these metrics using the 2010 rare earth element (REE) crisis as a case study. Our method is a novel application of Event Sequence Analysis, supplemented with interviews of actors across the entire supply chain....

This study presents a data envelopment analysis of environmental burden and mechanical properties obtained after production of 40 different types of steel.

Economic growth has caused a rapid rise in the use of metals and minerals. In addition, the world's population is projected to rapidly increase, with increases concentrated in Asia and Africa. Asia has become the largest global user of natural resources, and established systems of production and consumption are tailored to the current high levels o...

Steel is one of the most recyclable materials, and thus it is recycled repeatedly. When steel is recovered from end-of-life products, some materials containing tramp elements besides carbon steel are mixed into the scrap. Therefore, we must prevent contamination by tramp elements during repeated recycling. Meanwhile, there is little knowledge on tr...

Product lifetimes are a relevant topic of discussion towards establishing a circular economy, particularly in terms of the reduction of environmental impacts by improving product longevity. Various researchers have developed models to estimate actual lifetimes and have reported case studies for some product categories (e.g. electrical and electroni...

Recycling of neodymium and dysprosium is of great interest because of the rapid growth in their demand and limited supply of new resources. To promote recovery from end-of-life (EoL) products, it is desirable to quantify the recycling potentials of neodymium and dysprosium by their end use. This study characterized the substance flows of neodymium...

The concept of total material requirement (TMR) is introduced in this study in order to quantify the recyclability of scrap steel from an end-of-life (EoL) vehicle. The specific TMRs for the recycling of scrap steels (urban ore TMR, UO-TMR) from the EoL vehicle are estimated for four cases: conventional press-method, shredder and separation method,...

Economic growth is associated with a rapid rise in the use of natural resources, and has potential environmental impacts at local and/or global scales. Possible options to control environmental impacts associated with consumption of natural resources include the introduction of easier way to identify the consumption of natural resources and the ass...

Ensuring energy access should be at the core of SDGs to support a healthy life for all. Among the SDGs, even though Target 12.2 includes the ef cient use of natural resources, there is no explicit goal set for sustainable mineral use. Considering, however, that some metal supplies have drawn much attention in discussions of ‘critical metals,’ it is...

The transport sector in Japan emits a large amount of CO2. Passenger vehicles' and trucks' emissions are the largest part of the emission in the transport sector. Electrified vehicles are expected to be key technologies for reducing CO2 emissions. Using electric propulsion systems, such as hybrid system, the efficiency of vehicles for the propulsio...

In this study, a random sample of 107 steel bars from Japan and 26 steel bars from China were studied. Each specimen's elemental composition of tramp elements, such as Cu, Cr, Ni, and Sn, was analyzed. By using the compositions of specific tramp elements, electric arc furnace steel bars were distinguished. The distributions of the tramp element com...

Hibernating stock is defined as material stock that is no longer used, but is not yet recovered. Although hibernating stock plays a role in materials recoverability, its contribution to the overall material cycle is not clearly understood. Therefore, an analysis of the time-series potential generation of steel scrap in Japan was performed and compa...

In 2010 Chinese export restrictions caused the price of the rare earth element neodymium to increase by a factor of 10, only to return to almost normal levels in the following months. This despite the fact that the restrictions were not lifted. The significant price peak shows that this material supply chain was only weakly resistant to a major sup...

While depressing greenhouse gas emissions has become a common target for human society to tackle climate change, it may not necessarily be efficient that all of the sectors aim to achieve the reduction of greenhouse gas emissions by only themselves from the aspect of investment efficiency. When an intermediate product（like a semi-conductor）is devel...

This chapter introduces Life cycle assessment (LCA) as it can be used in connection with metals. Rather than stressing the connection of LCA with ISO standards, it evolves the methodology from its historical origins, chemcial engineering and accounting, and discusses it applicability to material specific issues. Beyond the obvious success of LCA an...

Closed-loop recycling of steel in automobiles is particularly difficult because of the low tolerance for impurities and the use of composites of various types of steel products. Technologies that reduce impurities or increase impurity tolerance must be developed and introduced to the steel recycling system at the appropriate time. This study evalua...

In this study, the concept of total material requirement (TMR) has been introduced to quantify the recyclability of scrap steel from end-oflife (EoL) vehicle. The TMRs for the recycling of scrap steels (urban ore TMR, UO-TMR) from the EoL vehicle have been estimated for four cases; conventional press-method, shredder and separation method, addition...

Synopsis : Various activities performed by the ISIJ social engineering division from 1995 to present is briefly summarized focusing on its contribution to environmental researches in steel science and engineering. Totally 10 forums including the young scientist forum and 8 research-projects in this division made extremely fruitful works. From 2010,...

In this study, a random sample of 107 steel bars from Japan and 26 steel bars from China were studied. Each specimen’s elemental composition of tramp elements, such as Cu, Cr, Ni, and Sn, was analyzed. By using the compositions of specific tramp elements, 99 of the 107 samples and 16 of the 26 samples were recognized as electric arc furnace steel....

In this study we introduce the concept of total material requirement (TMR) to quantify the quality of materials from end‐of‐life buildings. The TMRs for the recycling of materials (urban ore TMR [UO‐TMR]) from four types of Japanese buildings ( Japanese traditional wooden structure [ JTWS], wooden frame with walls structure [ WFS ], reinforced‐conc...

In this study we introduce the concept of total material requirement (TMR) to quantify the quality of materials from end-of-life buildings. The TMRs for the recycling of materials (urban ore TMR [UO-TMR]) from four types of Japanese buildings (Japanese traditional wooden structure [ JTWS], wooden frame with walls structure [ WFS ], reinforced-concr...

Interest in recycling of rare metals has greatly increased recently because of the rapid growth in the demand for, and uneven distribution of, natural resources. Substance flow analysis (SFA) is a useful tool for determining the flow of substances in specific geographic regions. However, few SFAs have been conducted for rare metals. In this paper,...

This paper discusses how the recycling of aluminum will change between now and 2050, focusing on the introduction of next-generation vehicles and scrap sorting. To evaluate the recycling potential, aluminum demand and discard in Europe, the United States, Japan, and China are estimated by material flow analysis (MFA). The MFA distinguishes between...

A sustainable materials management for metals should be achieved to conserve resources of metal minerals. For the sustainable materials management, material flows through the whole life cycle of materials have been recognized by material flow analysis (MFA) studies. Former MFA studies pointed out that cyclic use of metals could be enhanced not only...

A sustainable materials management for metals should be achieved to conserve resources of metal minerals. For the sustainable materials management, material flows through the whole life cycle of materials have been recognized by material flow analysis (MFA) studies. Former MFA studies pointed out that cyclic use of metals could be enhanced not only...

Recovery of materials from end-of-life products will contribute to the reduction in consumption of natural resources and global warming. For many decades, ships have been a major share of steel use, and used high quality steel products, mainly plates and high tensile strength steel. So, the steels contained in end-of-life ships should be useful for...

Recently, recycling of rare metals has been of great interest because of the rapid growth in their demands and maldistribution of the natural resources. Substance flow analysis (SFA) is a useful tool to figure out the flow of substance in specific regions. However, few SFA has so far been conducted for rare metals. In this paper, we focused on indi...

Recently, water scarcity has received attention. With the development of industries and the growth of population, the amount of water use has increased. In order to evaluate the water use of industrial products, the method of estimating water footprint (WF) has been developed. WF is defined as the amount of water use during the lifecycle of product...

Recently, copper price reached the highest level ever. It is expected that the rise of copper price becomes a strong incentive for recovering copper scrap from end-of-life products. Therefore, in this paper, we aimed to analyze the relation between copper price and the amount of recovered copper scrap in Japan. A dynamic material flow analysis (MFA...

The production of the platinum group metals (PGM) consumes large quantities of energy and induces a lot of carbon dioxide. The promotion of PGM recycling is important to construct a sound material-cycle society. In this article, a dynamic material flow analysis for PGM in Japan was conducted in order to evaluate the recycling potential of PGM. In J...

Recently, recycling of rare metals has been of great interest because of the rapid growth in their demands. Substance flow analysis (SFA) is a useful tool to figure out the flow of substance in designated area. SFA is sometimes used to quantify the recycling potentials of the substances. However, few SFA has so far been conducted for rare metals. I...

This paper dynamically analyzes the Japanese material flow of stainless steel. The substance flow analysis of Cr and Ni associated with stainless steel was conducted by classifying the material flow of stainless steel into two main alloy types: ferritic and austenitic. The substance flow covered more than 80% of Cr and Ni consumption in Japan. In m...

Lifespan of commodities is essential information for material flow analysis and material stock accounting. Lifespan data is available in the literature; however, it varies in definition and in methodology employed. This article reviews and categorizes different types of lifespan distribution and distribution estimation methodologies, and investigat...

We present a comprehensive analysis of steel use in the future compiled using dynamic material flow analysis (MFA). A dynamic MFA for 42 countries depicted the global in-use stock and flow up to the end of 2005. On the basis of the transition of steel stock for 2005, the growth of future steel stock was then estimated considering the economic growt...

Steel is the most widely used metal in the world. Many studies analyzing the flow and stock of steels have been conducted for Japan, Asian countries and the world. While top-down and bottom-up approaches have been used in these material flow and stock analyses, the applicability of these approaches is dependent on data availability. To overcome thi...

To reduce the amount of materials that are extracted from and emitted to the environment, reutilization and long-term use within our socio-economic system are important goals. From this perspective, the average number of times a material comes into use and the total average lifetime of a material are useful indicators for measuring the status of ou...

Lifespan is an essential parameter for the accounting and analysis of material stocks and flows, one of the main research topics in industrial ecology. Lifespan is also important as a parameter that portrays the current and historical situation of industrial metabolism, which is an area of interest to industrial ecologists. In the present article,...

Lifespan of product is essential information for material flow and stock accounting (MFA/MSA) as well as discussing possible contribution of product lifespan extension to waste prevention and materials/energy savings. There are a number of literatures on actual lifespan distribution of products in our society; however, existing information is not w...

Previous studies have pointed out that some quantity of ferritic stainless steel scrap is mixed with carbon steel scrap, thus resulting in the accumulation of chromium in carbon steel products. Chromium substance flow accounts for 97% of its consumption in Japan. This paper describes the analysis chromium substance flow in stainless steel, other al...