What Is Involved in Pig Iron Production?

Foundry pig iron is the basic charge for cast iron parts. The production and application of high-quality cast pig iron, especially high-purity pig iron, is related to the improvement of casting quality. The increase in the level of basic components, basic components and key components will inevitably promote the industrial upgrading and localization rate of China's equipment manufacturing industry, and will also greatly enhance the international competitiveness of China's equipment manufacturing industry.

The Fourth Session of the Eleventh National People's Congress mentioned that to truly transform our economy to rely mainly on

Canada, South Africa, Japan, the United States, Sweden, Norway, Germany, Russia and Brazil all have high-purity pig iron. Due to different mineral sources used in different countries, different production processes and different indicators of element content in high-purity pig iron, there is no uniform standard.

There are also "pure" problems with cast iron and cast steel. There are many grades of steel, and many elements are widely used as alloying elements. Pure steel (clean steel) is usually smelted in the main furnace and then refined in a refining furnace. The content of O, H, N, S, and P elements is strictly limited ( For example, the sum of S + O + P + N is less than 100 ~ 10r6). In addition, the content of constituent elements in steel must be stably controlled within a precise range. Of course, different steel types will also have their own special requirements, such as some bearing steels to remove Ti, some stainless steels to ultra-low C and so on. This is not the case for cast iron, which is a Fe.C-Si series material. Most cast iron structures have graphite. Graphitization is often considered during crystallization. Most cast iron parts are not heat treated or complicated. High-end cast iron parts should focus on the impurities and harmful phases in the grains and grain boundaries. Smelting of cast iron, unlike steel, uses scrap steel as the charge, and there are oxidation and reduction processes. Cast iron uses scrap, pig iron, and regrind as the charge, so it is necessary to be careful of the trace elements remaining in pig iron and scrap steel on the structure of cast iron. Therefore, the requirements of high-end cast iron for pig iron charge mainly focus on the content of S, P, Mn and harmful trace elements.

After analyzing the requirements for the chemical composition of cast iron, such as high toughness nodular cast iron parts for low temperature, isothermally quenched nodular cast iron parts, large nodular cast iron parts, special performance nodular cast iron parts and thin-walled high-strength gray cast iron parts, "Pure pig iron" grades, which specify the "special" and "1" levels of Ti, Mn, P, S, and Cr, V, Mo, Sn, Sb, Pb, Bi, Te, As, B, The maximum value of the respective contents of Al and the total content of Tj and the above 11 trace elements should not be greater than 0.1% ^[2]

1. For companies producing high-purity pig iron for casting method 2, 2010 is the year of extension, and a stable market has begun to take shape. However, in the face of the higher requirements of some high-end castings, the content of Ti and P needs to be further reduced, such as P0.02% and Ti0.02%. To this end, technical transformation should be carried out in accordance with the requirements of large-scale production, technological processes should be reorganized, and continuous improvement in technology should gradually get rid of the situation of relying on good ore to produce high-quality pig iron.

2. The high-purity pig iron produced by the method 1 has too little output and cannot accept larger orders. According to national policies, small blast furnaces cannot be expanded or newly built. Panxi and Chengde regions are rich in vanadium-titanium magnetite. Chenggang and Pangang are mainly engaged in steel, vanadium products and titanium products, and vanadium-titanium resource development companies. .

If it can be coordinated by the Ministry of Industry and Information Technology, some blast furnace molten iron will flow out of it to produce high-purity pig iron for foundry. This is a shortcut. For the relevant iron and steel enterprises, it is only a few percent of the amount of iron. Make up a notable gap in the foundry industry.

3. A foreign brand of high-purity pig iron has extremely low Ti content and more than 20 other elements, which is determined by its smelting process. As long as it is "pure" acceptable for cast iron parts. So far, the effects of trace elements and their limits in different circumstances have been mostly cited repeatedly without verification. It is suggested to take blast furnace enterprises as the main body, cooperate with users, and use the help of colleges and universities to summarize the appropriate trace element content in high-purity pig iron through accumulation.

4. The market for high-purity pig iron for casting has a nurturing process. Management needs to make predictions on the demand for high-purity pig iron for casting in the near-term and mid- to long-term.