Resource Integration at CSC
Kuan Nan Lin
1 Chung Kang Road, Hsiao Kang, Kaohsiung, Taiwan, R.O.C
Abstract
Located in Kaohsiung Linhai Industrial Park, China Steel Corporation (CSC), the only integrated steel mill in Taiwan, is considered one of the biggest by-products producers and receivers. CSC has accomplished the goal of zero waste thought 7 million residues are generated every year. This accomplishment is based on the cooperation with industries inside/outside the Park, through the incoming-producing recycling of the by-products. Besides, as being a integrated mill, which has great capability of recycling, CSC receives a variety of by-products from other plants as raw materials, assisting the Government and partners dealing with waste problems. Hence, being the hub of the network of materials exchanges and resource integration, CSC has made its Park as the Kalundborg in Taiwan, and become one of the most sustainable mills in the world. In this article, the industrial symbiosis network centered at CSC and some representative cases are presented.
Keywords: Industrial Symbiosis, Recycling, Zero Waste
1. Introduction
Sustainable development (SD) is the development that “meets the needs of the present without compromising the ability of future generations to meet their own needs.”, which is first defined by the the Brundtland Commission in 1987 [1]. In other words, SD is a pattern of resource use, that aims to meet human needs while preserving the environment so that these needs can be met not only in the present, but also for generations to come. Since sustainable development has become the unifying concept for worldwide activities, integrated steel mills have been working hard on every aspect toward this central guiding principle.
Resource recycling is one of the key issues toward sustainable development for mills, for the high resource intensity and the large quantity of by-products feature in mills’ processes. Hence, the leading mills in East Asia have achieved the recycling rate of at least 98% for by-products, which not only preserves resource but reduces the amount of waste for final disposal. Besides, they even recycle the waste from outside by utilizing the steelmaking infrastructure. In 2009, JFE steel helped to reduce society’s waste by taking in approximately 50,000 tons of waste plastic containers and packaging while Sumitomo metals accepted a total of 314,000 tons of externally generated waste and other materials for recycling.[2][3]
Since the vision of “why would not our industrial system behave like an ecosystem, where the wastes of a species may be resource to another species?” is first introduced in the article “Strategies for manufacturing” by Frosch and Gallopoulos (1989)[4], “Industrial Ecology (IE)” has become popular as a theoretical concept and that concept’s relation to industrial activities. Based on the concept of IE, Industrial Symbiosis (IS) is an approach that is practiced to achieve sustainable development. It is evident from the most often cited example of Kalundborg IS in Denmark that the industrial symbiosis approach could be a very successful one. Influenced by the example of Kalundborg, IS initiatives are being launched in the USA, Australia, the UK and most countries of Europe which symbolizes the revolutionary development of industrial symbiosis.[5]
Locate in Kaohsiung Linhai Industrial Park which is the biggest eco-industrial park in Taiwan, China Steel Corporation (CSC), as the only integrated steel mill in this country, dedicates itself to being the center of resource integration toward industrial-ecology and sustainable development. The introduction of CSC, the overview of Linhai Industrial Park, the integrated recycling system at CSC and the eco-industrial network are discussed as the following.
2. Kaohsiung Linhai Industrial Park and CSC
2.1. Overview of Kaohsiung Linhai Industrial Park
The establishment of the industrial park dates back to 1960 when the government enacted the Act of Encouragement of Investment and designated a hinterland for the industrial park to accelerate industrial development and to encourage overseas Chinese and foreign enterprises to make investments. In response to the expansion of the Port of Kaohsiung, one of the ten major construction projects, as well as to the demand for construction of steelmaking plants and shipyards, the government later exerted more effort to develop the industrial park in order to create an excellent investment environment, hasten the development of the major basic industries and enhance the overall economic growth of the country.[6]
The basic information of the park is shown in Table 1. It is a comprehensive industrial zone with 493 resident companies belonging to over two dozen industry types including base metals, metal products, machinery and repairs, nonmetallic mineral products, transportation and repairs, chemical products, food and beverage manufacturing, power equipment and repairs, etc. Resident companies include state-owned enterprises such as Taiwan Sugar Corporation, Tang Eng Iron Works Co., Dalin’s Refining Business Division, CPC Corporation, and the now privately-owned China Steel Corporation, China Steel Machinery Corporation, China Ship Building Corporation, and China Petrochemical Development Corporation. These companies are a bridge in the relationship between industrial and commercial businesses, as well as the backbone of economic progress in Taiwan.[7]
2.2. Profile of CSC
China Steel Corporation was established on 3 December 1971 with its first project being the planning of an integrated steel mill. The first phase of construction lasted from September 1974 to December 1977. Second, third and fourth phase expansion projects kicked off in July 1978, July 1984, July 1993 and concluded in June 1982, April 1988 and May 1997, respectively. Upon completion of Phase IV expansion project, CSC’s crude steel production capacity reached 8.054 million tons per year. Over years of equipment updating and improvement, the company set its annual crude steel production capacity at 9.55 million tons on 15 April 2003. CSC supplies steel plates, bars, rods, hot rolled products, cold rolled products, electrical sheets and electro-galvanized steel sheets.[8]
Figure 1 shows the CSC’s consumption and conservation of resources in 2010. By-products with the amount of 595 kg per ton crude steel in 2010 have been 100% recycled, 20.4% internally and 79.6% externally. This achievement of “zero waste” has been met since 2001 by turning by-products into useful resource through outstanding management and integration.
3. Resource Integration at CSC
Attributed to the variety of industries in Linhai Industrial Park, the early crosslink of resource between CSC and other companies in the Park was formed spontaneously by the motivation of cost reduction as Kalundborg in Denmark. As the government started promoting the integration of regional resources, the amount of linking companies within the Park was increasing accordingly. Besides, for the commitment of sustainable development, CSC stretched the link of resource integration over the Linhai Industrial Park, and the industrial symbiosis network centered at CSC has been formed.
The network is shown in Figure 2. There are 29 companies exchanging by-products with CSC in the network, among which 12 ones are inside the Park. In 2009, the amount of integrated resource in the network is 5.445 million tons, and the annual output value is as high as 883 million NT dollars.
Some representative cases are discussed in the following sections
3.1. The resource integration within the Linhai Industrial Park
Case 1: BF/BOF slag
Slag is the main by-product generated in mill’s manufacture process so the recycling of slag is always the priority for CSC. With the efforts over years, the pattern of BF/BOF slag recycling has been formed by CSC and China Hi-Ment Corporation (CHC) as shown in Figure 3.
CSC generates approximately 3 million tons of BF slag and 1.2 million tons of BOF slag each year. Slags are sold to CHC where the preliminary treatment is implemented for further application. Air cooling BF and BOF slags are used as fine aggregate of asphalt concrete and construction aggregates after crushing and screening. Granulated BF slag is transformed to BF slag powder and BF slag cement with higher value after being ground in CHC’s plant.
Case 2: De-S slag
De-S slag is produced during the de-sulfur process, a pretreatment of molten iron before entering BOF. There are approximately 0.3 million tons De-S slag generated by CSC, two third of which is sold to the companies inside the Park, as shown in Figure 4. After treatment, pig iron is picked to sell and De-S slag is used as graded aggregate, component of low strength concrete and fertilizer.
Case 3: Sludge and coal ash
Sludge is one of the major by-products in integrated steel mills. Most of the sludge generated from CSC’s manufacture process are recycled internally, but still some of them seeks for external recycling due to the recycling limitation of some unlovable components. With high quantity of Fe, Sludge is considered a good substitute for raw materials in cement industry. However, the application faced difficulties, for the problems of blocking and smell occurred during the usage of sludge in the cement manufacture process. In order to solve the problems, a research was conducted by CSC and the solution was found by mixing the coal ash generated from CSC’s boiler with sludge in a proper ratio.
Therefore, a mixing plant of sludge and coal ash was established, and has been operated by CHC since. Figure 5 shows the process. Besides using the by-products from CSC, the mixing plant also recycles the coal ash from Talin Power Plant in the Park. The product of the plant is sold to the cement plants in the eastern Taiwan.
Case 4: Tar-decanter sludge and waste oil
China Steel Chemical Corporation (CSCC) is CSC’s subsidiary which uses coal tar from CSC as raw materials to produce chemicals. Tar-decanter sludge is the solid part of coal tar and it cannot be used in CSCC’s process but recyclable in coke oven plant in CSC. China Steel Aluminum Corporation (CSAC), another subsidiary of CSC, generated waste oil which can also be recycled in coke oven plant in CSC. Therefore, the linking of tar and waste oil is formed in Figure 6.
Case 5: Scrap metal
The linking of scrap metal is shown in Figure 7. Scrap steel is recycled by CSC while other scrap metals are recycled by CSAC.
Case 6: Waste acid
Before the cold-rolling process, hot-rolling steel coil needs to be de-rust by hydrochloric acid In order to recover the waste acid, CSC has built 4 acid regeneration plants (ARP) which produce regenerated acid and high quality iron oxide powder. Other than regenerating waste acid within CSC, the ARP also recovers the waste acid from the member companies of CSC group, as shown in Figure 8. The produced iron oxide powder is sold to another subsidiary to manufacture magnetic materials.
3.2. The resource integration outside the Linhai Industrial Park
Case 1: De-S slag
As recycled in the Park, one third of De-S slag generated by CSC is sold to the other company outside the Park for the same application as shown in Figure 9.
Case 2: Reverse logistics of welding slag, waste grinding wheels and lime
Motivated both by the commercial and environmental reasons, reverse logistics of waste has been established between CSC and the suppliers, as shown in Figure 10.
Case 3: Spent refractory
The spent refractory generated from CSC is pretreated by CHC before recycling. After the processes of classification, broke and magnetic Separation, spent refractory is sold to the refractory plants as raw materials, as shown in Figure 11.
Case 4: Zinc
Zinc is a harmful substance for blast furnace during the iron making operation but it comes from the raw material and remains in the dust and sludge. In order to remove zinc before recycling dust and sludge , CSC has built the rotary hearth furnace (RHF) to concentrate Zinc. The product of RHF, coarse zinc oxide, can be sold to Japan as raw material of zinc refinery. On the other hand, zinc is used in continuous hot dip galvanizing line of CSC but also generates zinc doss, which can be recycled by the zinc oxide manufacturer. The link of Zinc is shown as Figure 12.
Case 5: Aluminum slag
Aluminum slag is an unpopular waste because of the stink of ammonia which comes from the reaction between water and aluminum slag. In Taiwan, aluminum slag becomes the environmental problem because of dumping by illegal secondary aluminum refineries. In order to assist government, CSC conduct a research of aluminum slag recycled in the de-sulfur process. The proposed reactions is shown as following equations:
CaO + S → CaS + O (1)
AlN + Al → 2A l+ N (2)
2Al + 3O → Al2O3 (3)
In the de-sulfur process, CaO serves as de-sulfur agent by the reaction (1). After aluminum slag is put into molten iron, reaction (2) occurs. The reaction (3) carries out after reduced Al is formed in (2) and hence accelerates the reaction (1) toward right direction enhancing the de-sulfur efficiency.
In 2010, the link of aluminum slag recycling has been established by CSC as shown in Figure 13. After collected and pretreated by CHC, aluminum slag is put into the CSC’s torpedo cars where the de-sulfur process implements.
4. Conclusion
With commitment of social responsibility and vision of sustainable development, CSC dedicates itself to being the center of resource integration forming the industrial symbiosis network. Great achievement of zero waste in CSC and annual output value of 900 million NT dollars have been met as the result of successful integration in the network. Besides the effective recycling of waste, solutions for government to deal with environment problems is also given through the function of the network.