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Since 1978, Shougang blast furnace has ranked the first in the country's large blast furnace. Before 1976, the grade of Qian'an concentrate was between 60% and 63%. Less than three years after 1977, the concentrate grade rose to 68.5% and remained so far. It has laid a solid material foundation for the improvement of the blast furnace index. In 1987, the concentrate grade was 68.42%, the sinter grade was 58.30%, the blast furnace utilization factor was 2.185t/(m 3 •d), the comprehensive coke ratio was 499.2kg, and the coke ratio was entered. 397.8kg, iron slag 362.kg. Bengang and Tangshan blast furnace production indicators are also domestically advanced, which is closely related to their raw material conditions.
China's blast furnace has proposed a fine material policy for 30 years. In the past 30 years, it has done a lot of work on blast furnace concentrates and achieved great results. Concentrate policy is multifaceted, iron materials, fluxes, fuel and other materials requirements, high quality, low impurities, uniform particle size, composition and stability, strength, and other properties to restore good metallurgical properties. At present, China's concentrate level still can not meet the needs of the blast furnace's increasingly intensified and large-scale, and there are still many gaps with the foreign advanced level. For example, the grade of ore in China is 3% lower than that in foreign countries, and the FeO of sinter is about 5% higher. The difference in composition and particle size uniformity and stability is greater. The development of pellets is slow. The coke ash is 2% higher than foreign countries, and the strength can not be met. Requirements, etc., so we must continue to work hard in the future of blast furnace concentrates.
Iron ore beneficiation process includes hard rock including important technical direction taken by the world is to improve the quality of concentrate, in order to achieve the production of iron reduces coke consumption, save energy, improve the economic efficiency of enterprises. The important technical measures taken for this purpose are to improve the selected depth of the ore and improve the quality of the ore before smelting. Generally, the savings in smelting costs brought about by the quality of the ore can be compensated for the cost of improving the quality of the ore.
In the twenty years before 1977, the grade of magnetite concentrate in China has been hovering between 60% and 63%. After 1978, due to the realization of new fine grinding and re-grinding technology, the grade of magnetite concentrate in China has been greatly improved.1986 In the year, the concentration of concentrate in China's key ore dressing plants accounted for 48.25% of the grade of more than 65%; the grade of concentrate production of local backbone ore dressings accounted for 53.7% of the grade of more than 65%.
The grades of China's hematite and polymetallic ore concentrates are not high. They were 58.80% and 56.21% in 1986 and 59.06% and 56.31% in 1987, respectively.
The characteristics of ore in China are rich ore, rich ore, complex ore type, ore type and its components and associated beneficial and harmful elements. The ore structure, structure and embedding granularity are quite different, most of the ore needs to be treated by mineral processing. 1986 In the year, 82% of the raw ore produced in China needs ore processing, and only 18% can be directly into the furnace. It can be seen that the development of China's steel industry is closely related to the technical level of the mineral processing technology.
In the past ten years, China's iron ore beneficiation selection technology has developed greatly, and some of the concentrating plant's production indicators have caught up to or reached the world level. Therefore, summarizing the practical experience of China's concentrators in the past ten years, especially the progress of ore selection technology, and how to determine the reasonable beneficiation depth according to their respective ore characteristics, is of great practical significance.
Modern iron and steel complex is a series of multi-process cooperation. Blast furnace smelting is a comprehensive reflection of production indicators of mining, selection, burning, coke, metallurgy and transportation. Mineral processing is one of the intermediate links. This chapter starts with the influence of ore selection on related processes, analyzes the input and output of ore selection, and further discusses the micro-efficiency and macro-efficiency of ore selection.
"Blast furnace must concentrate," This is the common conclusion smelting iron and foreign staff repeatedly recognized, it is the experience with a fundamental, iron production technology is the basis for all work. Soviet blast furnace workers believe that under certain equipment conditions, 70% of blast furnace production is in raw materials and 30% is operated. Since the 1960s, many large blast furnaces have been built in Japan and Europe along the coast and along the Yangtze River. Most of them use high-quality bonanzas in Australia and Brazil. The raw material preparation and sintering technologies have gradually developed, and they have reached a relatively perfect level. Their blast furnace indicators have always been advanced. The preparation of raw materials for Baosteel's blast furnace in China is based on foreign technical experience. In September 1985, Baosteel No. 1 blast furnace was put into operation. After one year, the blast furnace utilization coefficient and fuel ratio reached the domestic advanced level. In 1987, the blast furnace utilization coefficient was 2.077t/(m). 3 • d), the comprehensive fuel ratio is 494kg, and the coke ratio is 440kg.