JPS5959841A - Manufacture of material substituting for pig iron - Google Patents

Abstract

PURPOSE:To utilize effectively waste as a material substituting for pig iron by mixing shavings of an iron material as a principal component with waste dust such as scraps of a silicon carbide grindstone or graphite powder and by molding the mixture. CONSTITUTION:Shavings produced by cutting an iron material such as cast iron or steel are crushed to <= about 20mm. with a crusher or the like. The crushed shavings as a principal component are mixed with >=1 kind of waste dust such as scraps of a silicon carbide grindstone, graphite powder, coke breeze, dust collected in an electric furnace or collected silicon dust. The waste dust is pulverized to a grain size equal to that of the powder of the shavings before the mixing. <= About 1% org. or inorg. binder is added to the mixture, and the mixture is molded into a spherical shape or the like, dried, and calcined or sintered.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a material for replacing pig iron for the purpose of effectively utilizing waste.

Traditionally, metal materials have been processed using machine tools (e.g. lathes, drilling machines,
Metal scraps (cutting scraps, swarf, especially those produced by lathe work) are The powder (sometimes referred to as slag) has rarely been used effectively other than as a return material. Therefore, when cast iron cuttings were used as a raw material for cast iron melting, their value was only recognized as return material.

This invention was made with attention to these points, and the main component is iron material scraps produced by cutting, and silicon carbide grindstone scraps, graphite powder, coke powder,
The present invention provides a method for manufacturing a material for replacing pig iron, which is characterized by forming a mixture of one or more types of waste dust, such as electric furnace dust, silicon dust, etc. Explain details.

First, the iron material in this invention is an iron alloy based on an iron-carbon system such as cast iron or steel, and when it is cut with the machine tool described above, chips of various shapes are obtained. In general, the basic system of steel is iron-carbon, and alloys are obtained by adding various metals or changing processing conditions, heat treatment conditions, etc. Cast iron is an iron-carbon alloy with γ The solid solubility limit of carbon in iron is 1.7% or more, and it usually contains 1.5 to 2.0% silicon.The basic system that determines the properties is iron-carbon monosilicate, and carbon 3.0%. ~
3.5%, silicon 1.5-2.0%, manganese 0.3-0
, 8 times, 70.2-0.8%, sulfur 0.05-0.1
In addition to ordinary cast iron, which has a wide range of compositions such as 5%, there is also alloyed cast iron with additions of nickel, chromium, molybdenum, manganese, etc. In this way, steel also
There are a large number of metal scraps, and in order to use them, it is necessary to choose one with properties suitable for the purpose, so the composition of the metal scrap obtained by cutting and processing them is always constant. Not necessarily. Even if the composition of VJ shavings when mass-produced from raw materials of a certain April maturity is constant, there is a certain degree of variation in the composition of 17J shavings during low-volume, high-mix production. It is desirable that the layer is made to J+:4n (for example, 20 or less) using a crusher or a pulverizer.

Next, place a footrest on the cutting waste of such iron material.
- is mainly composed of silicon carbide; materials that contain a relatively large amount of silicon, such as grinding wheel scraps, dust collected (especially from air furnaces), and silicon steel dust, or the silicon carbide grinding wheel scraps mentioned above are also the same. However, conventional materials with the same composition, such as graphite (natural graphite, artificial graphite), coke powder, bone ash, materials made of carbon such as charcoal powder (corresponding to substances called carburizing agents, carburizing agents, carburizing agents, etc.) There was no effective way to use this material other than to return it to raw materials, bury it in landfills, or incinerate it. Although these are of the size of a heel seed, they are pulverized using a crusher or a pulverizer so that the particle size is at least equal to or smaller than the above-mentioned iron material powder.

When mixing waste dust with the iron powder obtained as described above, determine the composition of each powder in advance, and use one type of waste dust based on that, or mix two or more types of waste dust. After determining the amount of waste, the iron material powder and waste dust are mixed. Therefore, even though iron cutting waste alone has no value as a return material for raw materials for melting cast iron, by adding an appropriate amount of waste dust to it, the atmosphere in the melting furnace can be improved and carbon, silicon, and other components can be removed. Improvement of material quality through adjustment of
It is extremely significant that it is possible to easily replace pig iron, etc. while recovering resources, and that the type and amount of additives can be arbitrarily changed to make the material suitable for the desired use.

In addition, it is generally extremely difficult to homogeneously mix two or more types of powder that have a large difference in specific gravity, and at the same time, feeding the powder into a melting furnace, etc. causes scattering, making it impossible to achieve the purpose. Therefore, the powder after mixing is organic (
Add about 1% or less of a binder (for example, a sizing agent such as starch, a synthetic resin, etc.) or an inorganic binder (for example, a silicate compound) and use a tablet machine or press to form tablets into appropriate sizes (for example, about 5 to 30 mm). It is desirable to form the material into a spherical, cylindrical, rod-like, lump-like, or plate-like shape, and then perform various operations such as drying, firing, and sintering.

According to the invention described above, compared to pig iron, it is possible to increase the carbon and silicon content fT.
Not only does it have a 00% replacement capacity, but it also greatly contributes to increasing the steel scrap content and reducing the coke ratio and iron-silicon ratio. In other words, the coke ratio has decreased from the conventional 14% (including bed coke) to 12% (decrease rate of 14.3%), and 5% more in-house generated innovative bale (malleable coke) is used than in the conventional blend. It is possible to maintain the carbon beads at a constant value even when the temperature is low, and not only the cost of raw materials is reduced, but also the reaction rate in the cupola, high-frequency furnace, and low-frequency induction furnace is optimal, and a strong deoxidizing reaction is carried out. It can be said that the significance of this invention is extremely great because it has many excellent features that have not been seen in the past, such as producing a slag with high silica, high floatability, and good ML properties.

Examples of this invention are shown below.

[Example 1] 970k powder made by turning 63.2% Si and 2.0% Si cast iron into a 5 mm pass.
g, 15 kg of silicon carbide grindstone powder, 15 kg of graphite,
Further, sodium silicate was added as a binder to a concentration of 1% or less and mixed well. This was molded into a cylindrical shape with a diameter of 13Q mm and a length of $Qmm using a press machine of a00 kg/cm2, and was fired at about 600°C. The obtained fired product and pig iron were mixed in an amount of 10% each, and then
Contains 40% surface steel scrap and 50% return material, and uses this as a compact (55K)
VA) After placing it in a high frequency melting furnace and maintaining it at 1480℃ for 2 minutes, the C02 mold (diameter 45mm, 3Qmm, QQmm
It was cast into a test piece with a length of 170 mm. What was obtained by this series of operations was C3.4%, Si1
．． g%, Mn9.5%, P 0.035%, 50.04
%, and the tensile strength kgf/cm2, hardness H, chill depth during melting, and graphite morphology showed the values shown in Table 1. From this result, what was obtained with this invention is pig iron (JI
It has been found that the quality is equivalent to that of Class 1 No. 1 pig iron for S standard castings, and that it can completely replace pig iron.

Table 2 [Example 2] Produced in the same manner as in Example 1 by adding 36 kg of electrostatic precipitator dust to 964 kg of dust powder, and adding 10 kg of each of it and pig iron.
% and 40% of the wood chips and 50% of the return material were mixed therein, and a dissolution experiment was conducted using the experimental method of Example 1 to compare mechanical properties, graphite morphology, etc. The second result is
Shown in the table.

From these results, it has become clear that the product obtained by this invention has the same quality as pig iron and can completely replace pig iron.

[Example 3'J Silicon dust was mixed with pig iron powder and processed into a pre-kent shape, followed by cupola melting. As a result, the yield was about 88% when conventionally fed in lump form from the top of the furnace, and 92% when mixed into briquettes.

In general, silicon dust collection dust is cheaper than lumps and has a good yield, allowing for significant cost reductions.

[Example 4] First, 15% pig iron was blended and melted in a cupola, and at a certain point, an experiment was conducted by replacing it with pig iron powder briquettes containing 3% graphite. Table 3 shows changes in primary crystal i'i degree, C analysis value, and ladle temperature over time. As a result of replacing pig iron in this way, the average o, 22
%, and stable dissolution results were obtained.

As a result of obtaining a high C value, in order to return to the previous C value, steel scraps were increased by 4% and melting was performed. The result is the fourth
The third indication is shown in the table.

As described above, the graphite-containing pig iron powder briquettes are
4 Higher C value was obtained when used as a substitute for surface pig iron.

Therefore, the increased C value could be used instead of steel scrap. There was no change in the hot water surface pattern and chill depth.

Patent applicant: Kobayashi Shoji Co., Ltd.

Claims (1)

[Claims] The main component is cutting waste from iron materials generated during cutting, and one or two types of waste dust such as silicon carbide grinding wheel waste, graphite powder, coke powder, electric furnace dust, silicon dust, etc.
A method for producing a material for replacing pig iron, which is characterized by mixing and forming seeds or more.