Special cleansing agent for short-flow high-strength cast iron and manufacturing process thereof

Abstract

The invention relates to a special cleansing agent for short-flow high-strength cast iron and a manufacturing process thereof, belonging to the technical field of cast iron production flow. The cleansing agent consists of the following components in parts by weight: 6-18 parts of rare earth oxide, 29-49 parts of calcium oxide, 19-29 parts of aluminum oxide and 4-8 parts of carbon. The cleansing agent is manufactured by the following steps of: based on rare-earth selected mineral powder, high-purity calcium oxide powder, bauxite powder and coke powder as raw materials, adding a fluxing agent, roasting a mixture of the raw materials and the fluxing agent at high temperature, and electrically melting and spraying the mixture to obtain the special cleansing agent. The special cleansing agent disclosed by the invention can change conditions of thermodynamics and dynamics of a metallurgical reaction of blast-furnace molten iron, and eliminates or restrains a hereditary defect of vicious expansion of thick graphite of the blast-furnace molten iron so as to form a comprehensive strengthening effect with an inoculant; and high-strength cast iron mainly comprising A-type graphite and havingmore than 95% of pearlite and 250-350MPa of tensile strength can be obtained.

Description

technical field [0001] The invention belongs to the technical field of cast iron production process, and in particular relates to a short-process high-strength cast iron special purifier and a preparation process thereof. Background technique [0002] The short-process high-strength cast iron smelting process is to directly add blast furnace molten iron to the intermediate frequency electric furnace and scrap steel to melt and cast castings. This technology shortens the process flow and eliminates the remelting link of the conventional process. It can make full use of the heat of blast furnace molten iron and reduce The consumption of electric energy or coke, while greatly reducing dust and smoke emissions, has obvious economic and social benefits. [0003] Although the short-flow smelting process has significant advantages in energy saving and emission reduction, it has not been widely used and can only be used to produce castings with simple shapes and low requirements for...

AI Technical Summary

Problems solved by technology

This is due to the lack of a solidification link in the short-flow smelting process. A large number of non-metallic inclusions and gases generated during the blast furnace metallurgy process are mixed into the molten iron. During the solidification process, various inclusions form irregular graphite cores, making the graphite form Malignant enlargement (see figure 1 shown), forming so-called hereditary coarse graphite defects, resulting in deterioration of mechanical properties

Therefore, the short-flow melting process is difficult to meet the technical requirements of high-strength casting metallographic structure (mainly A-type graphite, pearlite content as high as 95%) and mechanical properties (tensile strength 250-350MPa), thus affecting the short-flow melting process. Promotion and Application

[0004] At present, most of the cast iron short-process technology adopts overheating, heat preservation and inoculation treatment technology, such as Sun Jianxing, etc. in the "Casting" Volume 55, No. 8, a "Blast Furnace-Intermediate Frequency Electric Furnace Dual Short Process Melting Process", for overheating, heat preservation Due to the lack of purification treatment process, or because the genetic influence of blast furnace molten iron has not been fundamentally eliminated, only HT200 (tensile strength below 200MPa) brand cast iron can be produced

However, the purification agent represented by Tieshen No. 1 (ZL200410033193.7) currently used in the market, although it has shown good results in the conventional cast iron smelting process, cannot eliminate or inhibit the coarse graphite in the blast furnace molten iron in the short-flow smelting process. Genetic influence, so the effect is not satisfactory in the short-flow high-strength cast iron smelting process

[0005] In addition, the common purification agents at home and abroad are made by melting raw materials, pouring them into blocks, cooling, and mechanical crushing. The activity is reduced, and the metallurgical reaction speed is slow. In addition, improper operation can easily cause entrained inclusions, resulting in secondary pollution during the smelting process

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