Development and Evolution of Aluminum Industry in China Based on Aluminum Flow Analysis

2.1 Method

Substance flow analysis (SFA) is an effective tool for studying the industrial metabolism of specific substances (e.g., aluminum, copper) on a certain spatial scale, for example, on the scale of a nation, a region or a firm. Industrial metabolism means the whole integrated collection of physical processes that convert raw materials and energy, plus labor, into finished products and wastes. Therefore, the subject of SFA is to identify and quantify the material flows related to those physical processes and the relationship among them[13]. The purpose of SFA is looking for the potentials and measures of resource conservation and environment protection, and encouraging industrial system to meet the requirement of sustainable development. Thus, the proposals offered in SFA can be of assistance to decision makers.

The aluminum flow diagram for the aluminum products life cycle is given in Figure 1.

Figure 1

Aluminum flow diagram

The entire life cycle of aluminum products comprises four stages. Some explanations for the four stages are as follows [10, 14]:

1. Production: Bauxite mining/milling, the production of alumina and aluminum has been treated as a separate process, and is shown at stage I. The dissipating amount of Al-containing materials during this stage contains tailing, red sludge and slag.

2. Fabrication & Manufacture: The stage II is the fabrication and manufacture stage of the aluminum products. Aluminum flows within this stage include the fabrication of aluminum semis and aluminum alloy semis, and the manufacture of intermediate commodities and finished products.

3. Use: Aluminum products leave the manufacture stage in the form of finished products or being embedded into assembled products. When the aluminum products are produced, they are widely used in national economy, such as constructions and vehicles, and so on.

4. Waste Management: The retrieve of obsolete aluminum products is the fourth stage in aluminum cycle. Some of obsolete aluminum products are retrieved after their life cycle Δτ, while some are permanently stored in terrestrial establishments and constructions, otherwise, they will be dissipated into environment during their life cycle.

2.2 Relevant Indices

The items described in Figure 1 are listed in Table 2, we can obtain some important aluminum flow indices based on these parameters (see Table 2).

The indices can be divided into three categories:

1. Resources self-support ratio and resources imported ratio

   Resources self-support ratio is the self-produced resources accounted to total resources input, while resources imported ratio is the imported resources accounted to total materials imput.

2. Aluminum scrap use ratio

   Aluminum scrap use ratio is the scrap used accounted to total resources input.

3.1 Aluminum Flow Diagram of China in 2011

Based on China Nonferrous Metals Industry Yearbook, etc[15], a aluminum flow diagram for the aluminum products life cycle of 2011 in China can be drawn to reflect the directions of Al-flow and the distribution of aluminum based on the application of the conservation law at every stage with the following-observing method of substance flow analysis (see Figure 2 and Table 3).

Figure 2

Aluminum flow diagram in China in 2011 (unit: 10⁴t-Al/a)

Corresponding data of aluminum flow described in Figure 2 are shown in Table 3.

3.2 Al-containing Materials Flow and Corresponding Aluminum Flow Indices in 1990, 1995, 2000, 2005 and 2008–2011

Similar to the diagram described in Figure 3, aluminum cycles in China in 1990, 1995, 2000, 2005 and 2008–2011 were also analyzed. The values of Al-containing materials flow are described in Table 4.

Figure 3

Net imported Al-contained resources in China in 1990, 1995, 2000, 2005 and 2010

Based on the aluminum cycles in China during these years, materials flow indices of aluminum industry were also analyzed (see Table 5).

4.1 Indices Analysis for the Year 1990, 1995, 2000, 2005 and 2010

1. Net imported of Al-contained resources (Figure 3)

   Bauxite in China during 1990 and 1995 was in a state of net exports, and then the net imports of bauxite increased year by year, especially from 2005 to 2010 net imports of bauxite rose from 575000 tons to 8.0454 million tons, the growth is significant. At the same time, the quantities of China’s net imported aluminum scrap increased year by year. Aluminum products consumption increased quickly with the rapid development of Chinese economy, as there is a shortage of bauxite resources in China, make the production of aluminum industry in China depend on foreign imports of bauxite and aluminum scrap to a certain extent.

   In the period 1995–2010, China’s aluminum, aluminum alloy and aluminum products were changed from net imports gradually to a net export state, the main reason is with the rapid development of China’s economic and industrial smelting technology and progress, makes the domestic production of aluminum products at a faster rate than the growth of the domestic aluminum products needed for consumption. But alumina production in China has maintained a net import state, this is mainly due to the production of raw material for aluminum is mainly alumina, and with the increasing of primary aluminum production in China, the production for alumina is sure to increase.

2. RSR of alumina, aluminum and aluminum industry (Figure 4)

   

   Figure 4

   Resources self-support ratio of alumina, aluminum and aluminum industry in China in 1990, 1995, 2000, 2005 and 2010

   In 1990, production of alumina and aluminum had almost completely self-support. Its resource self-support ratio of alumina production dropped from 100% in 1990 and 1995 to 57.58% in 2010. This is mainly because with the rapid increase of alumina production, bauxite appears more and more insufficient, the raw materials for alumina production depended on imports of bauxite.

   In 2010, resources self-support ratio of primary aluminum production increased, close to 90%. Except in 1990, the whole aluminum industry has a relatively stable its self-support ratio of raw materials, basically remain unchanged.

3. Aluminum scrap use ratio (Figure 5)

   

   Figure 5

   Aluminum scrap use ratio in China in 1990, 1995, 2000, 2005 and 2010

   Self-produced aluminum scrap use ratio presented downtrend basically, the main reason is that average use life aluminum products is longer, which is about 15–16 years, and now the old aluminum scrap used is generated from aluminum products put into use about 15–16 years ago. Aluminum products consumption 15–16 years ago is much smaller compared with now, so the proportion of old scrap reclaimed and recoveried in the aluminum production is even much small, the scrap use ratio declined gradually on the overall trend.

   Since 1995 the imported aluminum scrap use ratio was greater than self-produced aluminum scrap use ratio, which is closely related to China has imported a lot of aluminum scrap in recent years. Due to the imported aluminum scrap use ratio is relatively stable, which compensate the decline of self-produced aluminum scrap use ratio to some extent, so the total aluminum scrap ratio fluctuated, but the change is not large.

4.2 Indices Analysis for the Year 2008–2011

1. Net imported of Al-contained resources (Figure 6)

   

   Figure 6

   Net imported Al-contained resources in China in 2008–2011

   Net imports of bauxite increased obviously in 2008-2011, aluminum scrap also had a small increment in general, the net imported alumina had an obvious decrease trend. Aluminum alloy and aluminum products were net exported during this period, and primary aluminum were also in a net exported state in 2010 and 2011. In 2008-2011, net imports of Al-containing resources have edged up on the whole

2. RSR of alumina, aluminum and aluminum industry (Figure 7)

   

   Figure 7

   Self-sufficiency rate of alumina, primary aluminum production and the entire aluminum industry in China in 2008–2011

   Resource self-support ratio in alumina production has been reduced since 2009, which showed alumina production was more dependent on foreign bauxite

   Resource self-support ratio in aluminum production continued to increase during the period 2008-2011, this is because the rapid increase of alumina production in China.

3. Aluminum scrap use ratio (Figure 8)

   

   Figure 8

   Aluminum scrap use ratio in China in 2008–2011

   Self-produced auminum scrap use ratio were kept constant during 2008–2011. Imported aluminum scrap use ratio was greater than self-produced aluminum scrap use ratio. In 2011, imported aluminum scrap use ratio and overall aluminum scrap use ratio declined obviously, which was mainly affected by the market price of aluminum products, it made the cost of imported aluminum scrap increased.