KR960003464B1 - Raw material for producing perrite dust for friction elements and the method of reduction thereof - Google Patents

Abstract

The iron powder for friction element is produced by reducing dust generated in iron and steel making process. The dust comprises (in wt.) 50-85% total Fe, 20-55 FeO, 30-55% Fe3O4, 2-12% CaO, 1-5% SiO2, 1-3% MgO, 1-3% MnO, and below 1% C, and has particle size of 40-250 mesh, apparent density of 1.5-2.2g/cc, intrinsic density of 4.0-5.0g/cc and porosity ratio of 45-65%. The dust is reduced at 1000-1200 deg.C for 20-60 mins., and annealed at 65-800 deg.C.

Description

Reduced iron powder composition for friction materials using dust collecting dust as a raw material, and a manufacturing method thereof

1 is a reduced iron manufacturing process of the prior art.

2 is a reduced iron manufacturing process of the present invention.

The present invention is applied to a variety of machinery, such as automobiles, agricultural machinery, heavy machinery, and date, and relates to a powdered iron composition for friction materials, which can prolong the service life without generating any toxic pollution harmful to the human body. The present invention relates to a reduced powdered iron composition for friction materials using dust as a raw material, and a method of manufacturing the same.

In general, friction materials, which are essentially used in various machinery, are mainly manufactured from asbestos, and thus have a problem of causing toxic pollution, which is extremely harmful to the human body from raw material processing to assembly and use in machinery.

Therefore, in the United States and Japan, reducing iron has been used in consideration of such a serious pollution problem and performance and life of the friction material.

However, reducing iron has severe fluctuations in the reduction treatment method and the physical properties of the reduced iron depending on the properties, chemical composition, and bonding structure of the raw material to be reduced. Incidentally, it is more advantageous for a raw material containing an appropriate amount of various oxides added to the iron, namely calcium oxide (CaO), silicon oxide (SiO ₂ ), alumina (Al ₂ O ₃ ), and the like.

Therefore, the lower the specific specific gravity and the higher the porosity, the better. There is a need for a powdered iron composition without abrasion damage of the friction surface.

Conventional manufacturing method of such reduced iron is made of mill scale with iron oxide (FeO) of 80% or more from Pyron Co., Ltd. and Kawasaki Steel Co., Ltd. in Japan. After the necessary post-treatment process, the grinding method is used to obtain reduced iron.

As a manufacturing method of these reduced iron, the process of using high-purity mill scale generated during hot rolling as a raw material [Fig. 1a] is a manufacturing method of pylon company in USA and Kawasaki ironworks in Japan, and solid powder coke (including desulfurized lime) as a reducing agent. In the crude reduction process, mill scale reduction, particle sintering, and carburization by powdered coke are carried out, and in the following reduction process, it is pulverized to 100 mesh or less, decarburized and annealed, and then pulverized again. You will get iron.

However, the method of manufacturing reduced iron using mill scale as raw material has to go through three or more grinding processes, takes a long time to complete the reaction in the reduction furnace, and needs to be subjected to decarburization and annealing heat treatment, in particular, by adding iron to mill scale again. It has to go through an uneconomical and complicated work process that seeks to reduce time and has a problem of low productivity.

In addition, Hoeganeaes, Sweden, has a high purity iron ore containing more than 70% of iron (T.Fe) and more than 95% of magnetite (Fe ₃ O ₄ ). Powdered iron is obtained in the same manner as in the reduction production method of steelmaking in Japan (Fig. 1b).

However, Korea has no high-purity iron ore like Sweden, and iron ore imported from Australia and Brazil is hematite (Fe ₂ O ₃ ), which has 60% of its iron content and is overly crushed and crushed. Fe ₂ O ₃ → Fe ₃ O ₄ → FeO → Fe It is necessary to go through the process of the reduction process is expensive and takes a long time, it is uneconomical, the manufacturing process is complicated and the productivity is low.

As described above, the method for manufacturing reduced ferrous iron shows that the selection of raw materials and the conditions for reducing treatment according to the above factors must be additionally determined to determine the level of economic efficiency, workability, productivity, and environmental pollution (occurring during crushing and grinding process). It can be seen.

Therefore, the object of the present invention is to ensure the economic performance, simplify the work, high productivity, etc., as the main raw material dust collection dust generated in domestic steel companies, and to increase the added value and reduce the environmental pollution by recycling dust collection dust, It is to provide a reduced iron composition for friction materials and a method of manufacturing the same, which combines the effect of importing raw materials in Korea.

The constitution of the present invention is to use the dust collecting dust generated in the steel company as a raw material and the conditions for reducing it with a base reducing agent.

As shown in Table 1, dust collection dust has a chemical composition of weight percent (wt%), 50 to 85% of iron (T.Fe), 20 to 55% of ferrous oxide (FeO), and ferric oxide (Fe ₃ O _4). ), 30 to 55%, calcium oxide (CaO) 2 to 12% silicon oxide (SiO ₂ ) 1 to 5%, magnesium oxide (MgO) 1 to 3%, manganese oxide (MnO) 1 to 3%, fixed carbon ( Fixed Carbon) It has a composition of 1% or less, its particle size is 40-250 mesh, its apparent specific gravity is 1.5-2.2g / cc, its true specific gravity is 4.0-5.0g / cc and its processing rate is 45-65%.

TABLE 1

Chemical Composition and Physical Properties of Dust Collecting Dust

Dust collection dust having such chemical components and physical properties is directly reduced by blowing gas reducing bodies in a tunnel-type reduction furnace, followed by slow cooling to obtain reduced iron through a light grinding process.

When the phenol resin is mixed with pearlite powder, rubber powder, paper powder, brass chips, cashew powder, bar sulfate and impression graphite, and the binder is heated and heated to 180-250 ° C. Excellent friction products with friction coefficients of 0.15 to 0.4 and heat resistance of 350 to 950 ° C can be obtained.

When described in detail with reference to the following examples.

Reduction of dust collection in the steel manufacturing process increases the apparent specific gravity to 0.02 to 0.07 g / cc, the total specific gravity to 1.0 to 1.5 g / cc, and the porosity to 8 to 12%. The shape of is mostly non-uniform, and the particle size after crushing is mostly less than 150 mesh.

Dust collection dust is maintained for 20 minutes when it reaches a certain temperature (650 ~ 800 ℃) during slow cooling after one reduction process as in Figure 2 without the need for drying and coordination reduction process. It is pulverized in a pulverizer and classified to 150 mesh or less on a screen to obtain powdered iron.

First, the gas reducing agent is blown 10 ~ 50Nl per minute, the reduction treatment temperature is maintained at 1000 ~ 1200 ℃, the reduction treatment time is at least 20 minutes to 80 minutes and at this time the gas reducing agent blown per 1Kg of dust collecting dust (Nl) ratio was made into 0.4-2.0. Since the surface of the reduced iron powder after reduction treatment is in the form of sintered phase and the particles are hardened in the process, the annealing process that relaxes the hardened particles is necessary to satisfy the friction condition. The annealing process does not use a separate process or means, if it is maintained for 20 minutes in the range of 650 ~ 800 ℃ during the cooling process, sufficient annealing treatment is completed.

In the first embodiment, the gas reducing agent (N1 / min) is suitably 15 to 40, and below 15, unreduced ferric oxide (Fe ₃ O ₄ ) or ferrous oxide (FeO) is present in a considerable amount, and 40 or more is reduced. It is uneconomical because it exceeds the gas requirement. Reduction treatment temperature is suitable for 1000 ~ 1200 ℃, and below 1000 ℃, a large amount of unreduced iron is present. Above 1200 ℃, sintering formation between particles is so strong that grinding cost is higher, and the porosity by sintering decreases physical properties. There is a problem that inhibits.

In addition, the reduction treatment time is suitable for 20 to 60 minutes, and less than 20 minutes, the reduction of iron oxide is insufficient, there is a considerable amount of iron oxide, more than 60 minutes is uneconomical and sintering will proceed in part.

Gas and solid ratio, that is, ratio of gas reducing agent input (N1) and dust collection amount (Kg) is appropriately 0.8 to 2.0, and below 0.8, unreduced iron remains due to insufficient amount of gas required for reduction reaction, and more than 2.0 Is more economic than necessary. The reduced dust collection dust is suitable to be kept for 20 minutes when it reaches 650 ~ 800 ℃ during the cooling process in order to remove the hardening of the particles. Wear of the friction surface occurs.

As in the examples, the chemical composition and physical properties of the reduced iron dust collected by dust collection are as shown in Table 2, in which iron (T.Fe) is almost metal iron (M.Fe), and in particular, all iron is reduced in oxygen. As the exits remain as pores, the weight and total weight are increased, and the porosity is increased by 10%.

TABLE 2

Chemical Composition and Physical Properties of Dust Collecting after Reduction

Therefore, the important porosity in the reduced iron is up to 55 to 75% to have excellent characteristics as a friction material and can maintain the frictional force for a long time without abrasion of the friction surface at all.

In addition, the various oxides contained in the reduced iron can be used without any additional point, and since the particle size of the dust collecting dust is 40 to 250 mesh, no need for coordination reduction process and crushing operation is required, and the processing time is extremely short, and the gas reducing agent can be easily injected. In very small amounts, reduced iron can be obtained without environmental pollution.

As a result, it is possible to manufacture reduced iron without collecting dust dust generated from steel companies (electric furnaces and electric furnaces). Firstly, the advantages obtained are as follows: First, high value added by recycling wastes, prevention of environmental pollution, and raw materials (iron ore). ), And the dust collection dust particles are fine, which greatly reduces the workability, contamination, expense, and processing time due to crushing and pulverization. In addition, the porosity is very high even before reduction, which has advantages and advantages that make the physical properties after reduction more advantageous.

Claims (2)

In powdered iron used as a raw material of friction materials for various machinery, the chemical composition is 50 to 85% by weight (T.Fe), 20 to 55% ferrous oxide (FeO), and ferric oxide (Fe ₃ O ₄ ). 30 to 55%, calcium oxide (CaO) 2 to 12%, silicon oxide (SiO ₂ ) 1 to 5%, magnesium oxide (MgO) 1 to 3%, manganese oxide (MnO) 1 to 3%, fixed carbon 1% It has the following composition, its physical properties are particle size 40-250 mesh, apparent specific gravity 1.5-2.2g / cc, true specific gravity 4.0-5.0g / cc, porosity 45-65 in mercury photosieve method The chemical composition produced by reducing dust collection dust of% steel manufacturing process by weight (wt) was 55 to 92% of iron powder (T.Fe), 53 to 90% of metal iron powder (M.Fe) and ferrous oxide (FeO). 2% or less, calcium oxide (CaO) 2-12%, silicon oxide (SiO ₂ ) 1-5%, magnesium oxide (MgO) 1-3%, fixed carbon (C) 0.5% or less, phosphorus pentoxide (P ₂₎ O ₅ ) 1% or less, sulfur (S) 0.5% or less, zinc oxide (ZnO) 0.7 or less, physical properties are apparent specific gravity 1.55 ~ 2.25g / c c, A reduced iron composition for friction materials, which is composed of dust collecting dust having a specific gravity of 5.0 to 6.0 g / cc, a porosity of 50 to 75%, a particle shape, and a pore distribution in a uniform state. The chemical composition of the powdered iron used as a friction material is by weight (wt) 50 to 85% of iron powder (T.Fe), 20 to 55% of ferrous oxide (FeO), and 30 to 55% of ferric oxide (Fe ₃ O ₄ ). , Calcium oxide (CaO) 2-12%, silicon oxide (SiO ₂ ) 1-5%, magnesium oxide (MgO) 1-3%, manganese oxide (MnO) 1-3%, fixed carbon (C) 1% or less It has a physical composition of 40-250 mesh, an apparent specific gravity of 1.5-2.2g / cc, a specific gravity of 4.0-5.0g / cc, and a porosity of 45-65% in the mercury photometer method. Reduction treatment of the dust collection dust having a gas reducing agent 15 to 40Nl / min, reducing treatment temperature 1000 ~ 1200 ℃, treatment time 20 ~ 60 minutes, gas / solid ratio 0.8 ~ 2.0 and annealing temperature after reduction 650 ~ 800 ℃ A method for producing a reduced iron composition for friction materials comprising dust collecting dust as a raw material.