Materials Transactions, Vol. 45, No. 11 (2004) pp. 3184 to 3193
#2004 The Mining and Materials Processing Institute of Japan
Material Flow Accounting for Metals in Japan
Shinsuke Murakami1 , Megumi Yamanoi2; * , Tsuyoshi Adachi2 ,
Gento Mogi2 and Jiro Yamatomi2
1
Sustainable Material Cycles Management Section, Research Center for Material Cycles and Waste Management,
National Institute of Environmental Studies, Tsukuba 305-8506, Japan
2
Department of Geosystem Engineering, Graduate School of Engineering, The University of Tokyo, Tokyo 113-8656, Japan
Planning transition from conventional mass production, mass consumption, and mass disposal society to JUNKANGATA-SHAKAI
(recycling-oriented society), requires detailed and accurate information concerning material flows, especially from the viewpoint of
dematerialization. However, as is well known, it is nearly impossible to observe every material flow directly. Hence, the importance of Material
Flow Accounting model has increased. In this study, a Material Flow Accounting model using input-output technique is developed for Japanese
metal flows. Since the model uses the Input-Output framework, it can be easily integrated with the MIOT (Monetary Input-Output Table) for
further simulation. However, the scope of this study is limited to static framework, because the primal goal is accuracy. The data for year 2000 is
organized with the developed framework, and gives the following results. Firstly, scraps play significant roles already. Second, non-ferrous
metals can be grouped into two types. The first group’s destination is mainly construction and machinery and these non-ferrous metals show the
similar pattern of destination as iron. This indicates that the flows can be roughly predicted from the iron flows. The other group shows no
uniform trend so that the flows are more difficult to predict than the first group.
(Received March 17, 2004; Accepted August 19, 2004)
Keywords: material flow analysis (MFA), substance flow analysis (SFA), material flow accounting, industrial ecology, Japanese metal flow,
input-output table
1.
Introduction
1.1 Background and purposes
As has often been said,1) anthropogenic activities are major
precursors of global environmental change. Material Flow
Analysis (MFA) will reveal the relationship between human
society and the entire ecosystem from the viewpoint of
materials and energies considered in the analysis. These
flows are taken as ‘‘Industrial Metabolism’’ and industrial
ecologists have been trying to identify. The revealed
relationship shows linkages between the two systems, thus
clarifying potential environmental problems related to the
flows. Moreover, the material and energy intensities of
human economies can be derived.
Material Flow Analysis always requires the considerable
amount of well-organized data from Material Flow Accounting, while such data is not always available. In the case of the
metals, the information exists, but lacks consistency. In this
paper, we present a framework for Material Flow Accounting
for metals in Japan. Then, the analysis with actual data for
year 2000 will follow.
The proposed framework follows the methodology called
Physical Input-Output model (PIOT). The definition of the
sectors similar to Monetary Input-Output Table (MIOT),2) so
that the model can easily be integrated with MIOT. This will
be a huge advantage when the model is expanded into
dynamic one.
Analysis for the flows in the year 2000 focuses mainly on
the flows of ‘‘DOUMYAKU-SANGYOU’’3) and the disposal
and reusing are beyond the scope for this time, thus the flows
cannot be closed. However, since metal scraps are often used
as the substitute inputs for the refineries and cannot be
separated from the flows from virgin ores, material recycling
*Graduate
Student, The University of Tokyo
is accounted and analyzed.
The information derived from this accounting is essential
for the estimation of the completely closed dynamic model.
In addition, the estimation process will identify the currently
unavailable though necessary data for the complete model.
This is one of the main objectives of this paper.
Of course, the accounted flows offer significant information to analyze. Amongst the information, the metal contents
in the final goods are considered most significant. Using this
information combined with the production data, the accumulation of the metal can be estimated and eventually the
potential scraps in the emissions can be derived in the
completely closed dynamic model.
1.2 Previous studies
Although this area has drawn the increasing interests, the
number of studies is still small. Many Substance Flow
Analysis (SFA) can be seen for metals, though their
objectives are capturing the environmental problems caused
by a specific substance studied. One previous study for metals
concerning Japan has been made by Kapur et al.4) The study
focuses only on copper flows, and Asia is chosen as the
geographical boundary. That paper is the outcome of the
project called STAF,5) which intends to assess the comprehensive global material cycles. Copper and zinc were chosen
as the initial objective for the project, and the paper reports
initial findings for copper in the Asian region. Kapur et al.
concluded as follows; Asia is net importer of copper, and the
rates of both use and discards in Japan are significantly higher
than those of the rest of Asian countries. Therefore, the
material flow of Japan is worth to be analyzed separately. The
Kapur paper is more macroscopic than this paper, though the
results of these two papers can be compared. The series of
papers from this group1,6–9) are also the outcomes from the
projects, focusing on Europe. These papers are more
Material Flow Accounting for Metals in Japan
converted into E-Table for analysis. In the following section,
these two tables and the accounting framework for E-Table
are introduced in detail.
Earth
(Environment)
Mining
Disposal
EOL Goods
Ore
Manufacturing
Extracting
Material
Recycling
Refinery
Material
Intermediate
Goods
Parts Reusing
Products Reusing
Final
Products
Human Society
(Stocks)
Fig. 1
3185
The material flows.
2.2 E-Table
2.2.1 The structure of E-Table
The estimated E-Table for this paper is shown in Table 1.
Since this submodel expresses the smelting processes, inputs
for this table are ores and scraps. And the outputs are
‘‘Materials.’’ Originally, the EOL goods was inputs instead of
scraps and outputs include parts and products via reusing.
However, as repeatedly mentioned, reusing is out of scope for
now.
All amounts are recorded with the unit of the metals
contained and following relationships must be hold.
X
X
AEvij þ
AEsij ¼ MI i ; for i ¼ 1 to m1 ð1Þ
j
X
j
AEvij þ FEvj þ EXvj IMvj ¼ CTEvj
ð2Þ
AEsij þ FEsj þ EXsj IMsj ¼ CTEsj
ð3Þ
i
comprehensive and include more expanded analysis using
statistical entropy analysis technique.9) The notable conclusion from the analysis is that European copper flows as a
whole neither concentrates nor dissipates significantly in the
region.
2.
Accounting Framework
2.1 Metal material flows
Figure 1 shows the metal material flows generally considered in this type of studies. However, in this study, not all
flows could be included. Disposal and two types of reusing
are out of focus. Mining is ignored, too. Thus, only solid lines
in the figure are the flows estimated and the dotted lines are
placed outside of the boundary this time.
In this accounting framework, ‘‘Materials’’ basically refers
the goods produced from smelters. Then, non-ferrous
alloys10) are categorized as ‘‘Intermediate Goods’’, not
‘‘Materials,’’ while the metal oxides are ‘‘Materials.’’
In the metal material flows, ‘‘Materials’’ have comprehensive and reliable information so that can be utilized as a
fundamental information for the overall accounting. Therefore, the flows are divided into two types, ‘‘Materials’’
extraction flows and manufacturing flows and both are
expressed in separated submodels. The submodels are called
E-Table and M-Table, respectively. M-Table follows the
usual Input-Output table with physical units, whereas ETable is in much simpler framework. However, the simplicity
of E-Table makes its estimation more difficult so that another
framework is required for accounting purpose.
Of course, the advantage of the Input-Output technique lies
in the fact that the one model can include everything in the
system. Then, excluding extraction flows seems the loss of
this advantage. However, the existence of so many byproducts in the smelting flows forced the separation.
SNA-style Input-Output (SNAIO) technique is an accounting framework rather than analytical, and allows to include
multiple products from one activity. SNAIO can be converted
into usual IO table afterwards. Then, smelting processes are
once accounted with modified SNAIO technique and then
X
i
This submodel intends to identify the balance of the
sources for each material and not easy to be estimated
directly. Therefore, all information available are accounted in
the framework introduced in the next section, and then
converted to the table shown in Table 1.
2.2.2 Estimation framework of E-Table
E-Table shown in Table 1 can identify the relationship
between the produced material and its source. For example,
the row vector of gold metal contains values both in gold and
copper ores columns, and these numbers are unknowns.
Thus, another framework for accounting is developed and
then converted into E-Table.
The developed framework largely owes to SNAIO table.
This technique has one obvious advantage over usual IO
technique in accounting: this allows to contain multiple
products from one industry, that is joint production. For more
details of SNAIO and its analytical techniques, see Fujikawa
(1999).11)
Goods and industries are distinguished in SNAIO technique, whereas in usual IO technique these two are equivalent
with the assumption of one activity-one products. Usual IO
table consists of one square matrix of goods-goods, or
industries-industries. However, SNAIO table has two rectangular matrices of goods-industries, and industries-goods.
A matrix of goods-industries is called use table (U-Table) and
its column vectors show which industry purchases which
goods in what amount. Another matrix of industries-goods is
called make table (V-Table) and its row vectors tell which
industry produces which goods in what amount. It is obvious
that this V-Table can contain multiple products from one
industry and does not require the previous assumption.
In this study, ‘‘Industries’’ in SNAIO are replaced with
‘‘Processes’’ of smelting. The proposed framework is shown
in Table 2. This submodel describes smelting industry. Both
natural resources and scraps are inputs from outside the
system and can be treated like as primary inputs. Then,
primary inputs vector of usual SNAIO is replaced by the
vector of natural resources and scraps inputs. Similarly, final
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S. Murakami, M. Yamanoi, T. Adachi, G. Mogi and J. Yamatomi
Table 1 Estimated E-Table in 2000.
Inputs
Scraps
Materials
production
Total amount
extracted
Virgin ores
AEv : m × v
MI : m × 1
Parts reusing
AEs2=0
0
PRU=0
Products reusing
AEs3=0
0
RU=0
FEs=0
FEv : 1 × v
Exports
EXs : 1 × ns
EXv : 1 × v
Imports
IMs : 1 × ns
IMv : 1 × v
CTEs : 1 × ns
CTEv : 1 × v
Outputs (i)
AEs1 : m × ns
Metals not extracted
Total amount
domestically inputted
Table 2
Detailed submodel for estimation.
Goods
Im.
R. & S.
Mat.
Processes
Goods: n'
Resource
& Scraps
: (v+ns)
U: n' × n
use table
Material
:m
Inputs from outside
Total supply
Total
demand
0
Intermediate
goods
Processes: n
Final
outputs
0
q: n' × 1
total demand
MI: m × 1
material outputs
x: n × 1
production
V: n × n'
make table
CTEv, CTEs
1 × (v+ns)
0
qt: 1 × n'
total supply
0
xt: 1 × n
cost
Material Flow Accounting for Metals in Japan
demands vector is replaced by material production vector,
MI. All numbers are accounted in the amount of metal
contained and no additional values exist. U-Table contains
the amount of goods used by each process, and the outputs
from each process are accounted in V-Table.
Only but not negligible problem left is the fact that all
amounts should be captured by the amount of the metals
contained, because that Material Flow Accounting is based
on the universal law of mass conservation. These data is not
available directly, thus should be estimated. The estimation
requires the composition of all goods, however the compositions are not stable. In this study, the values from previous
studies are used. Ideally, the compositions should be updated
every time the table is estimated.
With these compositions, the table can be filled. Then, the
conversion to E-Table follows. This conversion requires one
assumption concerning joint production. There are two
alternative assumptions used when SNAIO is converted into
usual IO table; industry technology assumption, or commodity technology assumption. A input coefficient matrix B are
defined as follows.
(
)
Uij
B ¼ bij ¼ t
ð4Þ
xj
Industry technology assumption is that inputs coefficients
of B is stable no matter how the outputs from the industries
vary. On the other hand, commodity technology assumption
is that the inputs for one product is unchanged no matter
which industry produced. Both assumptions seems strong.
However, in the case of this study, commodity technology
assumption is unacceptable. For example, the gold produced
as main products from gold ore must be produced from same
inputs as the gold metal as by-product from copper ore under
the assumption. So, the industry technology assumption is
adopted.
Now, another coefficient matrix D, which is often called
industry mix in SNAIO, is defined as follows. Then, the
following relationship must be kept.
q m ¼ B Dðq mÞ þ f
Vij
where D ¼ dij ¼
ðqj mj Þ
ð8Þ
should be held.
In this estimation, MI is exogenously given to the model
from some data source. Also, m is given. Thus, AEv and
AEs1 matrices are only unknowns left in E-Table. From the
eq. (8),
2
3
0 0 AEv; AEs1
6
7
0
ð9Þ
40 0
5
0 0
0
¼ IMðB DðI ðI IMÞB DÞ1 ðI þ IM B DÞf^ þ f^ Þ:
Using this equation, E-Table will be estimated from the
accounting model of Table 2.
2.3 M-Table
M-Table includes all manufacturing processes other than
mining and refinery processes. Then, ‘‘Materials’’ are not
allowed produced in this model. All ‘‘Materials’’ production
processes, which are refining processes, are described in
E-Table, and ‘‘Materials’’ are inputted into M-Table like as
domestic imports. M-Table is shown in Table 3. Except for
the existence of a column vector, DIM, this table is basically
same as usual IO Table. And the following relationships must
be held for keeping mass balance.
CTm ¼ AM þ EX þ FD DIM IM
X
where AMi ¼
AM i
ð10Þ
j
2.4 Metal material contained
Identifying the amount of ‘‘Materials’’ contained in each
product is one analytical goal of this study. The methodology
is introduced here. The material balance of the table
introduced in the previous section can be rewritten as the
following eq. (11). If E-Table contains the information
concerning reusing, DIM2 vector is not zero vector. However, this is zero in this study.
where
0
ð5Þ
MI
1
B
C
DIM1 ¼ @ 0 A
ð6Þ
Using this IM matrix, the eq. (5) is
q m ¼ ðI ðI IMÞB DÞ1 ðI þ IM B DÞf:
m ¼ IMðB DðI ðI IMÞB DÞ1 ðI þ IM B DÞf þ fÞ
¼ AM þ EX þ FD DIM1 DIM2 IM
Then, since any processes in this submodel does not
produce any natural resources nor scraps,
m ¼ ðB Dðq mÞ þ fÞ IMðB Dðq mÞ þ fÞ
2
3
I 0 0
6
7
where IM ¼ 4 0 0 0 5:
0 0 0
Thus,
CTm ¼ AM þ EX þ FD DIM IM
m ¼ ½CTEv; CTEs; 0 . . . . . . ; 0:
2
3
0
6
7
f¼4 0 5
MI
3187
ð7Þ
AMi ¼
X
0
and
0
1
B
C
DIM2 ¼ @ PRU A ¼ 0
0
ð11Þ
RU
AM i
j
n
.
o
Am ¼ Amij ¼ AM ij CTmtj
‘‘Import,’’ ‘‘Export,’’ and ‘‘Final Demand’’ can be treated
as exogenous. However, ‘‘MI’’ should be able to be derived
endogenously.
Let F1 denote everything other than intermediate demands
and MI. MMI is the matrix, which has same the dimension as
AM. Since no goods belonging to ‘‘Material’’ should be
produced inside ‘‘Manufacturing Table’’, then the following
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S. Murakami, M. Yamanoi, T. Adachi, G. Mogi and J. Yamatomi
Table 3 M-Table.
N×N
N×1
ð12Þ
0
Using this equation, eq. (11) will be
CTm ¼ AM þ F1 MMIðAM þ F1Þ
¼ Am CTm þ F1 MMIðAm CTm þ F1Þ
ð13Þ
1
¼ ½I ðI MMIÞAm ðI MMIÞF1
With this eq. (13), we can derive CTm from F1. Then,
substituting this into eq. (12), DIM can be derived.
DIM1 ¼ MMIðAmf½I ðI MMIÞAm1
ðI MMIÞF1g þ F1Þ
ð14Þ
With this eq. (14), the repercussion effect from the
increase in the final demand sector onto the material inputs
can be derived. Assuming one unit increase in F1 of a final
product, MI will be derived. This is the one of the most
important characteristics of this model. The meaning of the
derived MI for one unit of F1 of one specific final product is
the metal contained in one unit of the final product.
Hence, substituting an identity matrix into F1 of eq. (14),
MC matrix will be derived. This MC matrix has same
dimension as MMI or Am.
MC ¼ MMIðAmf½I ðI MMIÞAm1
ðI MMIÞIg þ IÞ
2
3 2
3
I MCI MCF
MC2
6
7 6
7
MC ¼ 4 0
0
0 5¼4 0 5
0
0
0
0
EX
FD
CTm
N×1
N×1
N×1
N×1
RU
DIM1 ¼ MMIðAM þ F1Þ
¼ MMIðAm CTm þ F1Þ
0
Control totals:
Domestic production
DIM= PRU
relationship must be hold.
0
Domestic final demand
0
where F1 ¼ FD þ EX IM DIM2
0
1
I 0 0
B
C
MMI ¼ @ 0 0 0 A
IMP
MI
0
Final goods
Exports
AM=
Intermediate
goods
Domestic inputs:
from E−Table
Final goods
0
Imports
Inputs (i)
Materials
Intermediate
goods
Materials
Outputs (j)
ð15Þ
This MC2 matrix should have same dimension as AEs1 in
the Extraction table. With this calculation, the metal
materials contained in per unit goods are derived in the form
of the matrix, MC2.
In order to make further analyses, another conversion
matrix, MCM (Metal Contained in Material) is required.
This matrix has the dimension of ‘‘the number of the metals
studied the number of materials’’. This MCM matrix will
be known by the materials definitions. For most materials
studied, their compositions are defined by industrial standards, like as JIS (Japan Industrial Standard).12) The composition may vary a little. In this study, the composition defined
by JIS is used for this MCM matrix and also as the estimation
foundation in E-Table.
These MC and MCM matrix will be used in order to
convert the goods flows to materials, or metal flows. If one
unit of automobile is produced, multiplying the automobile
column vector of MC matrix with one, provides the amount
of each material used. Then, multiplying these amounts of
materials with MCM matrix, we will know how much metals
contained in one unit of automobile.
2.5 Accounting procedures
The outline of the accounting is follows. Firstly, data for
natural resources and scraps inputted to E-Table as inputs is
collected. Also, the production of the materials are captured
from both governmental and private statistics. Since the
compositions for the materials are available from industrial
standards, like JIS (Japan Industrial Standards), the metals
contained in the materials can be estimated. With these
information, E-Table can be estimated.
Next, the production of materials, MI, are inserted in MTable. It will be distributed to each direction. Only thing
worth to emphasize here is the following; since this model is
intended to describe the material transformations, the change
of ownership is not the issue of concern. The estimation of
M-Table sometimes utilizes information of MIOT, however,
the goods and services must be strictly distinguished. For
example, transportation sector purchases automobiles. Of
Material Flow Accounting for Metals in Japan
course, automobiles cannot be transformed into the goods
named ‘‘transportation,’’ but they are simply purchased as the
transporter. Hence, this difference is of vital importance, and
this is the reason why PIOT cannot be estimated automatically from MIOT.
All values must be accounted in the amount of the metal
contained. However, considering application later, the
amounts had better be accounted not only in the metal
amount but also in the appropriate unit.
For example, let’s assume the followings; electric wires
are demanded 100 meters domestically, and 20 meters for
exporting. However, 30 meters of cables are imported. On the
other hand, preceding estimation says 2700 kilograms of
copper and 900 kilograms of aluminum are used in the
production of electric wires. Then, domestic production of
the electric wires are expressed as 3600 kilograms of metals
contained. Then, the amount of imports should be expressed
as 1200 kilograms of metals contained. In this case, 3600
kilograms of metal is accounted as the domestic production
of the ‘‘electric wire.’’ However, if 100 meters are also
recorded, this plays huge role in further expansion of the
model, like as dynamic expansion.
In the estimation, inconsistency might occur, that the
summation of the rows and columns are not equivalent, and
of course it is not acceptable. Then, in order to make the
matrix balanced, RAS13) methodology is applied as necessary.
In the next chapter, the Japanese metal material flows for
year 2000 will be accounted and analyzed with this framework. The primal purpose is analyzing the metal material
flows for year 2000 in Japan, but deriving accurate MC
matrix is the another significant purpose.
3.
Analysis of the Flows for Year 2000
3.1 Findings from E-Table
From this section, the Japanese metal material flows for
year 2000 will be presented and analyzed. Firstly, the
findings from E-Table is introduced.
Nineteen metals are chosen for the analysis, mainly
because of the availability of data. However, the higher data
availability can be considered to reflect its importance in the
economy and thus appropriate standard for the choice. Gold,
silver, copper, lead, zinc, aluminum, nickel, chromium,
cobalt, molybdenum, manganese, iron, magnesium tungsten,
antimony, platinum, palladium, titanium, and tin are chosen
for this study. And the amount of these metals contained in
the flows are estimated.
Even though some data concerning reusing are not
available and excluded from the estimation, data for scraps
collected for recycling is available, hence the table was
successfully estimated. 23 types virgin resources and 13
scraps are input sources of this table, and 60 types of
materials are outputs.
In principle, the goods called ‘‘Material’’ in this model are
not alloys and should consist of single metal. Though, pig
irons and ferroalloys are exceptions. In addition, some scraps
directly appears as materials and they are sometimes alloys.
So many joint productions are found in the E-Table.
Especially, copper, lead, and zinc concentrates are significant
3189
sources for Japanese smelting. Originally, smelting industry
is highly horizontally integrated. Thus, the residues from a
smelting process is often inputted to another metal’s refining
process. As for copper, lead, and zinc, the number of
materials, which depend more than 20 percents of their
sources on these three concentrates, are 5, 7, and 3
respectively.
For example, lead and copper smelting processes are often
related with silver refining process. From the residues of
silver electro refining, gold, and the platinum groups metals
are recovered. Then, these materials heavily depend on
copper and lead concentrates. Japan has a gold mine,
HISHIKARI-mine, which produces high grade ores. However, even the ores mined in HISHIKARI are refined in the
company’s copper smelting process. These fact supports the
idea that E-Table should be able to describe joint productions.
3.2 Metals in each product
As mentioned in the previous sector, ‘‘Materials’’ were
divided into 60 types, although the number of the metals
concerned is 19. Then, ‘‘Intermediate Goods,’’ which sometimes go directly to final consumption, were divided into 66.
The number of ‘‘Final Goods’’ are 52. Unfortunately, data
were far from abundant and statistics from different sources
were utilized. In addition, the interview survey played
significant role in data acquisition. Still, as mentioned before,
the data for reuse was not available this time. After the data
collected as much as possible, each component of this table
were adjusted to make the matrix balanced.
With the methodology introduced in 2.4, the ratio of metal
materials included in each goods, MC is estimated. Multiplying the composition of each material, MCM, this MC
matrix can be converted into the matrix of metal contained,
MMC. The result is shown in Fig. 2. Obviously, almost all
final goods depend heavily on iron. ‘‘Rechargeable Batteries’’
is a rare exception, in which predominates other metals.
Titanium appearing in some sector is mainly pigments. Most
of the titanium used as alloys is exported and not much left in
Japan.
Construction and automobile industries use about 60
percent of domestically used non-ferrous metals in weight.
45 percent of the whole metal including iron goes to
constructions. Zinc, nickel and chromium used in construction industry are used as ingredients of steels.
3.3 Destinations for each metal
Although Fig. 2 shows a lot of implications, the detailed
characteristics are hardly seen, as base metals occupy the
huge amount in weight. Thus, from here, the each metal’s
destination is analyzed respectively. The destinations for
each metal are shown in the Fig. 3.
Gold: Large part of gold goes to various manufacturing
goods through electric devices. Also, metal products is
another huge destination. Very roughly speaking, gold is used
as points for electric devices, or simply kept as metal.
Silver: Large part of silver goes to chemical industry.
These silver is used as ‘‘Nitrate for Sensitizer’’ mainly for
photographs.
Tungsten: Tungsten is used as the ingredients of ferro-
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S. Murakami, M. Yamanoi, T. Adachi, G. Mogi and J. Yamatomi
Fig. 2
Metal contained in each product.
tungsten. However, superalloys are another destination and it
will be used as the material for the machineries.
Platinum: Platinum goes to chemicals or ‘‘Other machineries.’’ The former are as catalysts, and the latter are the
parts for electric devices.
Palladium: The destination of palladium varies. The fact
that platinum and palladium rarely go to construction makes
these two metals distinguishable from base metals.
Titanium: One strong characteristics of titanium is the
amount used for papers and publishing. Even though titanium
is often used as alloys, they are rarely left inside Japan. The
large part of titanium destination are pigments.
Tin: The reason why large part of tin is consumed for
electric devices is that the tin is a major component of solder.
Other than solder, tin is used as the ingredients of so many
alloys so that the destination varies.
Antimony: Antimony shows completely different trends.
This is mainly used for chemicals, though its final destination
varies.
Lead: Huge part of lead is consumed as rechargeable
batteries and the batteries are used for automobiles.
Copper: Copper’s destinations varies. Copper is used as
brass or electric wire. Main difference from other non-ferrous
base metals is that the large part of copper is used for
constructions.
Aluminum and Manganese: Comparing other base metals,
the ratio for automobiles is slightly larger than other metals,
in the case of aluminum. Since large part of manganese is
used as the ingredients for aluminum alloys, its destination is
similar to that of aluminum.
Zinc: Zinc is consumed as castings. However, huge part of
zinc is used as the ingredients of alloys like as brass, or
aluminum. Also zinc plating on steel is popular. Considering
these applications, the fact that its destinations varies seems
rational.
Iron, Cobalt, Magnesium, Nickel, Molybdenum, and
Chromium: Large part of these non-ferrous metals are used
as the ingredients of ferroalloys. Thus, the destinations of
these metals show similar trend as iron.
3.4 Total material flow balance
As usual in material flow analysis, the total metal material
flow is analyzed. The results are shown in Fig. 4.
As expected, Japan is obviously a resources importing
country. It heavily depends on imports for its virgin metal
resources, which occupies about 70 percent of its resources.
Domestically produced ore is only 0.15 percent of its total
resources. On the other hand, scrap fills the remaining 30
Material Flow Accounting for Metals in Japan
3191
Fig. 3 Destinations for each metal.
Imported Resource
85,199,246
Imported Material
6,051,533
Imported Intermed.
Goods
5,878,594
Imported Final
Products
5,011,793
Domestic Final
Demand
90,259,489
Domestic
Resources
176,757
Recyclable Scraps
Domestically Consumed
37,562,600
Fig. 4
Material Export
980,565
Intermed. Goods
Export
31,993,045
Final Products
Export
16,647,424
Aggregated material flows [tons].
percent. Aluminum and iron (including both steel and pig
irons) are large part of this. However, other scraps are not
small. Metals contained in ferroalloys can be considered
recovered as part of steel scraps.
In later stages of the flows, still, ‘‘Materials’’ import is
larger than its export. However, exports exceed imports for
the stage of intermediate goods and final goods. As is usually
considered, from the viewpoint of metal material consumption, Japan is a resources importing and products exporting
country.
Material flow balance for each metal is shown in Fig. 5.
Left hand side of this bar graph shows the ratio of metal
inputs into Japan, and the right hand side shows the output.
The metals are placed in order of the amount of domestic
virgin source plus scraps.
As for inputs, copper, zinc, iron, lead, manganese, nickel,
silver, gold, tungsten, antimony and titanium are supplied as
virgin resources imported. Aluminum, chromium, molybdenum, tin, palladium, cobalt, platinum and magnesium are
supplied through materials imported. For all metals, imports
as ‘‘Intermediate Goods’’ and ‘‘Final Goods’’ are very small.
Another thing should be mentioned here is that the
domestic productions of gold and silver are largely as
byproducts from copper smelting. Even though this cannot be
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S. Murakami, M. Yamanoi, T. Adachi, G. Mogi and J. Yamatomi
Fig. 5 Input output balance for each metal.
read from these graphics, this is an important information for
further simulation analysis.
As for outputs, though Japan is products exporting country,
still main destination for almost all metals are domestic final
demand. Only exception here is cobalt. Cobalt is used as parts
for rechargeable batteries and Japan is a large exporting
country for these batteries. Only palladium, platinum, and
titanium are exported as materials in significant amount.
Other than these three, metals are exported mainly as
intermediate goods or final goods.
4.
Concluding Remarks
In this paper, the framework for the metal material flow
accounting and some analytical technique was proposed, and
then the flows for year 2000 is accounted utilizing the
information mainly from existing statistics and analyzed. The
proposed framework consists of two submodels, called ETable and M-Table, respectively. With the introduction of E-
Table, which is specified for the smelting and refining
processes, joint productions in smelting processes can be well
described and also many existing analytical methodology for
Input - Output analysis can be utilized with some adjustment.
The well known fact that Japan is resources importing and
products exporting country is confirmed from the viewpoint
of metal material flow. This result is consistent with Kapur et
al.4) The importance of domestic scraps as source is
confirmed, too.
Since non-ferrous alloys and steels dominate the flow in
weight, the destinations for the metals, which used as
ingredients of the alloys and steels, are similar to those for
iron and other non-ferrous base metals.
Data for reusing cannot be collected with sufficient quality
for the accounting. Also, the exports of secondhand goods
cannot be captured. Even the model is expanded into
dynamic and closed, the lack of data for these two is
unacceptable. If either of these is acquired, another can be
estimated as difference.
Material Flow Accounting for Metals in Japan
The proposed framework can be easily expanded into
dynamic, and connected with MIOT. With the expansion, the
emission from the human society can be modeled and thus
further analysis will be made possible. However, this is out of
scope of this paper, and left untouched as future work.
The primal purpose of the proposed framework is to
account the domestic metal material flows in detail. Of
course, the framework itself can be applied to other materials.
However, the definition of sectors depends on the target
materials.
As long as possible, the flows should be traced over the
boundaries. In order to make international studies, the flows
of other nations should be accounted with the same framework and connected so that the more detailed analysis will be
possible. This remains as the future work.
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REFERENCES
1) T. E. Graedel: Eco. Econ. 42 (2002) 5–7.
2) Known as SANGYO RENKANHYO in Japanese.
3) ‘‘DOUMYAKU’’ is the Japanese word meaning ‘‘artery’’ and
12)
13)
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‘‘SANGYO’’ means industry. This word refers traditional manufacturing industries and the antonym for ‘‘JOUMYAKU (vein)-SANGYO,’’
which refers industries concerning disposal, recycling, and reusing.
This metaphor comes from the analogy between material cycles and
blood circulatory systems.
A. Kapur, T. Bertram, S. Spatari, K. Fuse and T. E. Graedel: J. Mater.
Cycles Waste Manag. 5 (2003) 143–156.
Stocks and Flow Project at the Center for Industrial Ecology, Yale
University.
T. E. Graedel, M. Bertram, K. Fuse, R. B. Gordon, R. Lifset, H.
Rechberger and S. Spatari: Eco. Econ. 42 (2002) 9–26.
S. Spatari, M. Bertram, K. Fuse, T. E. Graedel and H. Rechberger: Eco.
Econ. 42 (2002) 27–42.
M. Bertram, T. E. Graedel, H. Rechberger and S. Spatari: Eco. Econ. 42
(2002) 43–57.
H. Rechberger and T. E. Graedel: Eco. Econ. 42 (2002) 59–72.
Ferro alloys are categorized as ‘‘Materials,’’ since pig iron is ‘‘Material’’
and exists in the same stage of the steel making cycle.
K. Fujikawa: Input-Output Analysis of Global Economy, (Sohbun-Sha,
Tokyo, 1999).
Japan Industrial Standards are defined by Japan Standard Association.
As for RAS method, see M. Kuroda, K. Shinpo, K. Nomura and
N. Kobayashi: KEO Database, (Keio University Economic Observatory, 1996) pp. 95–99.