Optimization of Iron and Steel Production Process Toward Green Manufacturing
Abstract
Iron and steel production process is highly energy-intensive and resulted in a large amount of emissions. To achieve the purpose of green manufacturing, process optimization is the prerequisite and effective approach. This paper puts forward the optimization ideas and methods of iron and steel production process from three aspects of raw materials, production processes and post-treatment technologies. The optimization is mainly reflected in the improvement of iron ore mineral processing technology, gradual improvement of ironmaking process and technology, intelligent control of steelmaking process and deep processing of products. At the same time, this paper also analyzed the advantages and disadvantages of the existing technologies, and discussed their corresponding development trends.
1 Introduction
Iron and steel industry is an important basic industry for Chinas modernization process. With the advancement of the socialist market economy and the deepening of reform, the iron and steel industry has developed rapidly, and the scale of production, productivity and labor productivity have been significantly improved. However, the process of iron and steel production process is highly energy-intensive, which is accompanied by a large amount of pollution. According to statistics, the iron and steel enterprises account for about one-third of the entire energy consumption and emissions in China, 80% of the consumption of fossil energy and 70% of the total emissions. The pollution caused by the iron and steel industry is becoming increasingly prominent. In 2014, China issued the Environmental Management Plan for the Iron and Steel Industry and proposed that the target of energy and environmental protection be realized in 2020.
In order to meet the requirements of environmental protection policies, the energy-saving transformation and environmental protection transformation of iron and steel production process is implemented. And the process optimization is the prerequisite of all these transformations. This paper puts forward the optimization ideas and methods of iron and steel production process from three aspects of raw materials, production processes and post-treatment technologies.
2 Analysis and Optimization of Raw Materials
2.1 Analysis of the existing technologies
Raw materials are the basis for the production of iron and steel products. At present, Chinas iron ore generally adopts the open-pit mining method, which involves a large amount of energy consumption and environmental pollution. In addition, the ore grade of the mined ore is lower and the content of refractory elements is higher, so the treatment difficulty is greater. The existing concentrating process is usually composed of three stages, crushing and screening, magnetic separation and flotation. The overall power consumption is high, and the beneficiation index, such as the concentrating grade, recovery rate and separation efficiency, needs to be improved.
2.2 Improvement measures
2.2.1 Improvement of ore reclaiming technology: ore reclaiming is the key process for reducing energy consumption and improving beneficiation index of iron ore. The selection of ore reclaiming equipment should combine the system design and products of material level, coupled with the control of automatic and semi-automatic equipment, so that the reclaimer has strong maneuverability and flexibility, high efficient and stable.
2.2.2 Optimization of ore beneficiation technology: The optimization of ore beneficiation process should focus on the improvement of three main contents, that is, the breakage process, Mineralization process and regeneration process. For example, magnetic separation process and gravity separation process can be added to the breakage process. In the Mineralization process, appropriate stirring agents and flotation agents must be added to improve the separating effect. In the regeneration process, the solid waste recovery rate is improved by developing new tailings regeneration technology.
3 Optimization of ironmaking process
3.1 Analysis of the existing technology
At present, the production of iron and steel is mainly based on coal and metallurgical coke. The existing ironmaking process is generally divided into two categories: blast furnace smelting and direct reduction. The traditional blast furnace smelting process is semi-open, with a large amount of heat dissipation, and its production capacity and efficiency are far from what modern fuels and power machines can match.
3.2 Improvement measures
3.2.1 Rational use of fuels: Ironmaking furnace can not completely put out the fire during the cooling process, so it is necessary to use appropriate fuels for cold initial ignition to reduce energy consumption.
3.2.2 Comprehensive Utilization of Waste Heat and Comprehensive utilization of Gas: The utilization of waste heat is to reduce the energy consumption of production, while the comprehensive utilization of gas is to achieve the purification of exhaust gas and reduce air pollution.
3.2.3 Adjustment of furnace structure: furnace structure directly affects the rationality of blast furnace smelting process. The optimization of furnace structure is to reduce heat consumption, improve the energy efficiency and reduce the waste of resources.
4 Optimization of Steelmaking Process
4.1 Analysis of the existing technology
Steelmaking technologies have evolved from primitive small furnace smelting and semi-continuous refining to the large-scale use of electric arc furnaces, submerge arc furnaces and steel converters. The current control technology of steelmaking process is divided into two categories, conventional and new technology. The traditional mode has a low efficiency and a large energy consumption.
4.2 Improvement measures
4.2.1 Development of intelligent technology: Intelligent technology has been recognized by more and more steelmakers as an effective means to optimize steelmaking process, because intelligent technology can transfer from conventional control to intelligent control, making steelmaking process more reasonable and efficient.
4.2.2 Development of on-line process monitoring: By monitoring the process parameters, it is possible to detect abnormal information of smelting process in time and take corresponding control measures, so as to realize reasonable use of energy and improve the energy utilization rate of smelting process.
5 Processing of Steel Products
5.1 Analysis of the existing technology
At present, the method of steel product processing is usually pickling and oiling or pickling, cold rolling and hot rolling. The former has the disadvantages that the surface of steel products is not smooth, the size is not accurate, the surface quality is not good and the production cycle is long.
5.2 Improvement measures
5.2.1 Development of rolling mill automation technology: The development of rolling mill automation technology is a kind of optimization to improve efficiency and reduce energy consumption. The technology improves the accuracy of rolling mill, reduces the cycle time and improves the production efficiency.
5.2.2 Development of surface treatment technology: The development of new surface treatment technologies such as laser cladding, physical vapor deposition and tape diffusion, can realize the heat treatment of metal surface without the application of external power and reduce energy consumption.
6 Conclusion
In order to realize the purpose of green manufacturing, the optimization of iron and steel production process is necessary. This paper has analyzed and put forward the optimization ideas and methods of iron and steel production process from three aspects of raw materials, production processes and post-treatment technologies. First of all, the optimization of raw material includes the improvement of ore reclaiming technology and the optimization of ore beneficiation technology. Secondly, from the optimization of the ironmaking process, the rational use of fuels, the comprehensive utilization of waste heat and gas, and the adjustment of furnace structure can be carried out. Thirdly, for the optimization of steelmaking process, the development of intelligent technology and online process monitoring are adopted. Fourthly, the development of rolling mill automation technology and surface treatment technology should be carried out to optimize the processing of steel products. These optimization ideas and methods can be combined and followed to realize the goal of green manufacture.
