High efficiency, high yield and environmental protection of blast furnace converter steelmaking technology
Blast furnace, converter steel manufacturers are facing ore / scrap prices change radically, natural gas prices low, aging facilities and the increasingly stringent environmental regulations and other issues. Therefore, in order to deal with these problems, it is necessary to apply flexible technology to make full use of the advantages of raw materials and energy, while avoiding potential technical defects. This paper describes a highly flexible blast furnace converter steelmaking technology with high energy efficiency, productivity, output and emission reduction under different raw materials and energy structures of Tenova company.
3 technologies to improve energy, productivity and environmental flexibility
(1) facilities and discharge pressure facing integration transformation: many of the old steel plant is currently restricted - such as the recent coke oven and blast furnace in North America the new "green" blast in 1980s entrusted to the Canadian Steel Corp LakeErie factory. If there is no new equipment and facilities, the existing coke oven and blast furnace facilities are faced with such problems as low productivity, high operating costs, high maintenance and maintenance costs, and emission reduction control. In the face of large capital expenditures, many steel mills have decided to close the blast furnace and coke oven, thus limiting the use of hot metal and the production capacity of the factory. In addition, the integrated steelmaking production is facing more and more pressure to reduce greenhouse gas emissions, which needs to rethink the traditional coke iron ore blast furnace technology.
(2) low risk strategy to solve the problems of integration facilities: taking into account these technical measures for new breakthrough and the uncertainty of the time limit, the integrated steelmaking plant needs a lower risk, can solve the problem of coke oven / blast furnace production capacity is limited and aging facilities, emissions and other technical measures.
The main reason for the higher emission of greenhouse gases is the reduction of iron ore. Therefore, to improve the integration of steelmaking process under the proportion of scrap and dri use, can greatly reduce the greenhouse gas emissions of specific steel, iron and steel enterprises are facing the challenge of how to effectively improve the use of metallic iron in integrated steelmaking processes. Using CONSTEEL technology can also be in the scrap / metal ratio under the condition of 50/50 operation.
However, taking into account more than 70% of greenhouse gas emissions from blast furnace, method of reduction of iron ore with coke on practical measures to cut greenhouse gas emissions in the integrated steelmaking process is to change the traditional. In 1998, Austen et al. Kinetics of blast furnace loading of broken steel was studied. The results show that, with the best mode into scrap can greatly reduce fuel ratio and improve productivity. The scrap into charge can highly increase the yield of the blast furnace, and the coke rate decreased, but some people worry that a substantial increase in consumption will lead to scrap metal residues, especially in blast furnace production of high quality steel in converter. Due to concerns about metal residues, they think in charge can be used in the direct reduction of iron or iron scrap instead of hot pressing.
Through metal HBI and direct reduction iron blast furnace test made gains in productivity and coke ratio. That small scale, commercial blast experiment, with a ton of iron as a benchmark, regardless of charge is with direct reduction iron scrap or HBI /, a ton of metal iron added to the burden will save 310 kg of coke, and hot metal production will be improved significantly. For example, 30% iron material charge is metal case of iron HM production has been proved, the average yield increased by about 25%.
Therefore, the blast furnace with hot iron and direct reduction iron instead of iron ore will greatly enhance the production capacity of iron, and significantly reduce the coke consumption. This strategy can significantly reduce the demand for coke, thereby reducing the operation of coke oven. In addition, higher production of molten iron on the one hand can promote higher steel production to meet market demand, or to reduce the size of the smaller blast furnace operation, reduce operation and maintenance costs. As described below, the use of blast furnace and direct reduction iron HBI will significantly reduce the integrated steelmaking process of greenhouse gas emissions, so as to make it comply with future emission reduction targets.
(3) TenovaHYLENERGIRON Technology: ENERGIRON technology is currently in the forefront of the direct reduction industry, and continuous improvement. ENERGIRON technology is currently available for shaft furnace without external gas conversion equipment of iron ore reduction process, carbon dioxide capture rate of 90%. This process can produce very stable high carbon direct reduction iron products.
ENERGIRON technology is characterized by its flexible process configuration, able to meet or even exceed the current global stringent environmental requirements. The process of waste gas and waste water discharge is not only small, and easy to control.
Traditionally, the use of natural gas as a fuel for the production of direct reduced iron, and the recent rapid development of shale gas and its price and supply advantages of direct reduction of iron has become a competitive raw material. For example, Nucor has changed its original plan in Louisiana to build a ENERGIRON DRI production factory, the factory of high carbon direct reduction iron production capacity is 2 million 500 thousand tons. Compared with the production of blast furnace, direct reduction iron factory Nucor will benefit from iron and steel production can be used in low-cost, clean natural gas to reduce greenhouse gas emissions and energy consumption.
(4) the risk of blast furnace direct reduction iron production is low: Knop et al. Suggest that the TenovaHYLENERGIRON process can be transformed into the use of blast furnace gas and coke oven gas instead of natural gas. As a result, the application of HYL direct reduction iron production to the traditional blast furnace production will greatly promote the production of hot metal, coke consumption and greenhouse gas emissions.
