Method for preparing powder metallurgy oil bearing product by using waste copper-tin-clad steel wires

Abstract

The invention discloses a method for preparing a powder metallurgy oil-retaining bearing product by using waste copper-tin-clad steel wires. The method comprises the following steps: (1) smelting and refining the recycled peeled waste copper-tin-clad steel wires; (2) adding copper and / or tin for continuous smelting according to the furnace-front component analysis result of the peeled waste copper-tin-clad steel wire and the need, and preparing pre-alloy powder by using a water atomization method; (3) drying the pre-alloyed powder to obtain powder A; (4) adding copper oxide powder into the powder A, uniformly mixing and then reducing; (5) crushing and screening the powder obtained after reduction to obtain powder B required by the powder metallurgy oil bearing; and (6) carrying out compression molding on the powder B to obtain an oil-retaining bearing green body, and sintering to obtain an oil-retaining bearing product. According to the method, metal resources in the waste copper-tin-clad steel cable are recycled and are converted into raw materials of the powder metallurgy oil bearing through specific process treatment, and high-value utilization of waste is achieved.

Description

(I) Technical field

[0001] The invention relates to the fields of resource recycling and powder metallurgy, and in particular to a method for preparing a powder metallurgy oil-containing bearing product by utilizing waste copper-tin clad steel wire. (II) Background technology

[0002] With the acceleration of the global industrialization process, the treatment and recycling of electronic waste such as discarded copper-tin-clad steel cables has become increasingly prominent. These wastes contain a large number of valuable metal resources, such as copper and tin. If they can be effectively recycled, they can not only reduce environmental pollution, but also save resources, and have important economic and environmental value. The Chinese government attaches great importance to the resource utilization of solid waste and has introduced relevant policies to encourage and support the comprehensive utilization and harmless treatment of waste.

[0003] As an advanced material preparation technology, powder metallurgy has developed rapidly around the world in recent years. This technology uses metal powder as raw material, and manufactures metal materials and products with specific properties through processes such as pressing, sintering and subsequent treatment. The powder metallurgy process has the advantages of high material utilization, low energy consumption, and low environmental pollution, and can produce complex shapes and high-performance components that are difficult to achieve with traditional processes. As an important mechanical component, powder metallurgy oil-containing bearings are widely used in many fields such as automobiles, home appliances, and motors. This type of bearing has the advantages of self-lubrication, long life, and low noise, and no additional lubricating oil is required during operation, reducing maintenance costs and environmental pollution. However, in the preparation process of traditional powder metallurgy oil-containing bearings, the selection of raw materials and cost control have always been the focus of industry attention.

[0004] Waste copper-tin-clad steel cables contain a certain proportion of copper and tin, which are the main components of common high-cost-effective copper-iron composite powder metallurgy oil-containing bearings. In this context, the development of technology to reuse waste copper-tin-clad steel cables to prepare powder metallurgy oil-containing bearing products not only responds to the country's policy call for waste recycling, but also provides a new solution for the source of raw materials for powder metallurgy oil-containing bearings. (III) Summary of the invention

[0005] The purpose of the present invention is to simplify the disposal and reuse process of traditional copper-tin clad steel cables that require comprehensive multi-metal recovery, efficiently and directly utilize discarded copper-tin clad steel cables to prepare powder metallurgy oil-containing bearing raw materials with excellent performance, reduce production costs, and achieve high-value utilization of waste materials.

[0006] To this end, the present invention provides a method for preparing a powder metallurgy oil-containing bearing product using waste copper-tin clad steel wire, and the specific process is as follows:

[0007] (1) smelting and refining the recovered peeled waste copper-tin clad steel wire;

[0008] (2) according to the furnace composition analysis results of the peeled waste copper-tin clad steel wire and the need to add copper and / or tin for further smelting, and then using a water atomization method to obtain a pre-alloyed powder;

[0009] (3) drying the pre-alloyed powder obtained in step (2) to obtain powder A;

[0010] (4) adding the powder A obtained in step (3) to copper oxide powder, mixing well and then reducing;

[0011] (5) The powder obtained after reduction is crushed and sieved to obtain powder B required for powder metallurgy oil-containing bearings;

[0012] (6) The powder B obtained in step (5) is molded to obtain an oil-containing bearing green body, and then sintered to obtain an oil-containing bearing product.

[0013] Further, after all the waste copper-tin clad steel wires are completely melted in step (1), a refining agent is added for refining. The refining agent is composed of dried aluminum carbonate, magnesium carbonate, calcium carbonate and Al 10 Si alloy particles, wherein aluminum carbonate accounts for 20-30% of the total mass, calcium carbonate accounts for 20-40%, magnesium carbonate accounts for 5-10%, and Al10Si alloy accounts for 20-30%. Furthermore, the amount of the refining agent added is 0.5-1.5% of the mass of the peeled waste copper-tin clad steel wire.

[0014] The aluminum, magnesium and calcium in the refining agent of the present invention are added in the form of carbonates to produce a foaming effect in the melt, which can be better dispersed; the aluminum in the Al10Si alloy particles added to the refining agent can remove oxygen from the melt and reduce part of the oxides, while the aluminum itself is oxidized to micro-nano-scale Al 2 O 3 , which can play a role in strengthening the matrix; the remaining silicon is dissolved in the melt and then oxidized to play a role in refining and slag making. Small and medium-sized oxides and impurities can be removed through slag making, and the refining effect is better.

[0015] Furthermore, the addition of copper and / or tin in step (2) can be adjusted according to the needs of different products; preferably, the mass percentage of copper in the melt after the addition of copper and / or tin is 10-25%, and the mass percentage of tin is 9-12%.

[0016] Furthermore, the mass percentage of copper in the melt after addition is controlled to be 15-20%.

[0017] Furthermore, in step (2), the particle size of the water atomized powder should be controlled to be greater than 50% of the -325 mesh powder.

[0018] Furthermore, in step (4), the amount of copper oxide powder added is 1-2% of the mass of powder A; the added copper oxide powder can be reduced to copper powder in the subsequent reduction, thereby improving the sintering activity of the pre-alloyed powder. Furthermore, when copper oxide powder is added, it is preferably ultrafine copper oxide powder with a particle size of -800 mesh.

[0019] Furthermore, copper powder can be further added in step (4) so ​​that the total copper content in the powder (copper in powder A + copper in copper oxide powder + added copper powder) is 15-20% by mass.

[0020] Furthermore, in step (4), the reducing atmosphere is an ammonia decomposition atmosphere, and the reduction time is 30-90 minutes, preferably 60 minutes.

[0021] Further, the bulk ratio of the powder B obtained after crushing and sieving in step (5) is 1.8 to 2.2 g cm -3 , -325 mesh powder accounts for no less than 30%.

[0022] Furthermore, in step (6), the compression molding has a relative density of 75 to 80%.

[0023] Furthermore, in step (6), the sintering temperature is 850-900° C., the sintering atmosphere is ammonia decomposition gas, and the sintering time is 40-80 min.

[0024] Compared with the prior art, the beneficial effect of the present invention is that the present invention recycles the metal resources in the discarded copper-tin clad steel cables, and converts them into raw materials for powder metallurgy oil-containing bearings through specific process treatment, thereby realizing high-value utilization of waste and having significant social and economic significance. (IV) Description of the drawings

[0025] Figure 1 is a SEM image of the iron-copper based pre-alloyed powder prepared in Example 2;

[0026] Figure 2 This is a photograph of the oil-containing bearing product prepared in Example 2. (V) Specific implementation methods

[0027] The present invention is further described in detail below in conjunction with specific embodiments and the accompanying drawings. A person of ordinary skill in the art will be able to implement the present invention based on these descriptions. In addition, the embodiments of the present invention involved in the following description are generally only embodiments of a part of the present invention, rather than all embodiments. Therefore, based on the embodiments of the present invention, all other embodiments obtained by a person of ordinary skill in the art without making creative work should fall within the scope of protection of the present invention.

[0028] As described in the invention, the composition analysis of the melt in the smelting process is carried out by X-ray fluorescence spectrometry; the particle size of the powder formed by smelting and diffusion is tested by laser particle size analysis, and the loose density of the powder is tested by Hall flow meter. The oil content of the oil-containing bearing sample after sintering is measured by drainage method according to Archimedes' principle; the radial crushing strength of the bearing is measured by SANS-CMT5105 universal material testing machine, and the compression speed is 5mm·min -1 According to the GB / T6804-2008 standard, the radial load is slowly and continuously increased on the bearing sample until the sample breaks, and the crushing load (also called the maximum crushing load) is measured. In the provided embodiment, all the test green samples are uniformly pressed into annular samples with an outer diameter of 12.00 mm, an inner diameter of 6.00 mm, and a height of 8.00 mm by compression molding, and the molding density is 5.80-5.90 g·cm -3 The % mentioned in the present invention are all mass percentages.

[0029] Example 1

[0030] 89.0 kg of bare wire of waste copper-tin clad steel cable composed of 81% steel, 18% Cu and 1% Sn was used as raw material for medium frequency furnace smelting. After smelting, 445 g of refining agent was added. The refining agent composition was 30% aluminum carbonate, 35% calcium carbonate, 8% magnesium carbonate and 27% Al10Si alloy.

[0031] Then, 9.5 kg of tin was further added, and the mixture was smelted evenly and then water atomized to make powder. By controlling the water atomization process parameters, the proportion of -325 mesh fine powder in the alloy powder was 56%. The obtained powder was dried and 2 kg of -800 mesh ultrafine copper oxide powder was added. After the powder was mixed evenly, it was reduced for 60 minutes in an ammonia decomposition atmosphere at 700 ° C, and then crushed and sieved to obtain the iron-copper based pre-alloyed powder required for the oil-containing bearing. The pre-alloyed powder had a bulk ratio of 2.05 g cm -3 The powder was molded to a relative density of 75%, and sintered in an ammonia decomposition atmosphere at a temperature of 850°C for 60 minutes. The oil content of the oil-containing bearing product obtained after cooling was 24.6% and the crushing strength was 230 MPa.

[0032] Example 2

[0033] 83.0kg of bare wire of waste copper-tin-clad steel cable composed of 84.5% steel, 15% Cu and 0.5% Sn was used as raw material for medium frequency furnace smelting. After smelting, refining agent was added for refining. The refining agent composition was 30% aluminum carbonate, 40% calcium carbonate, 5% magnesium carbonate and 25% Al10Si alloy. . Due to the serious oxidation of the raw materials, the amount of refining agent added was 0.8% of the raw material mass, that is, 664g. Then 3.0kg of copper and 9.6kg of tin were further added, and water atomization powder was made after smelting evenly. By controlling the water atomization process parameters, the proportion of -325 mesh fine powder of the alloy powder was 65%. After the obtained powder was dried, 1.6kg of -800 mesh ultrafine copper oxide powder and 3kg of copper powder were added. After the powder was mixed evenly, it was reduced for 60min in an ammonia decomposition atmosphere at 700℃, and then crushed and sieved to obtain the iron-copper based pre-alloyed powder required for the oil-containing bearing, and the pre-alloyed powder had a loose ratio of 1.95g cm -3 The powder was molded to a relative density of 76%, and then sintered in an ammonia decomposition atmosphere at a temperature of 890°C for 60 minutes. After cooling, the oil content of the oil-containing bearing product was 20.2% and the crushing strength was 296 MPa.

[0034] Comparative Example 1: Compared with Example 2, the only difference is that the relevant components in the refining agent are added in the form of oxides, and the refining agent is composed of 30% aluminum oxide, 40% calcium oxide, 5% magnesium oxide, 3% silicon dioxide, and 22% elemental Al.

[0035] 83.0 kg of bare wire of scrap copper-tin clad steel cable composed of 84.5% steel, 15% Cu and 0.5% Sn was used as raw material for medium frequency furnace smelting. After smelting, refining agent was added for refining. The refining agent composition is 30% aluminum oxide, 40% calcium oxide, 5% magnesium oxide, 3% silicon dioxide and 22% single Al. Due to the serious oxidation of the raw materials, the amount of refining agent added is 0.8% of the raw material mass, that is, 664 g. Then 3.0 kg of copper and 9.6 kg of tin were further added, and water atomization powder was prepared after smelting evenly. By controlling the water atomization process parameters, the proportion of -325 mesh fine powder of the alloy powder was 65%. After the obtained powder was dried, 1.6 kg of copper oxide powder and 3 kg of copper powder were added. After the powder was mixed evenly, it was reduced for 60 minutes in an ammonia decomposition atmosphere at 700 ° C, and then crushed and sieved to obtain the iron-copper based pre-alloyed powder required for the oil-containing bearing, and the pre-alloyed powder had a loose ratio of 1.95 g cm -3 The powder was molded to a relative density of 76%, and then sintered in an ammonia decomposition atmosphere at a temperature of 890°C for 60 minutes. After cooling, the oil content of the oil-containing bearing product was 22% and the crushing strength was 182MPa.

Claims

1. A method for preparing powder metallurgy oil-containing bearing products using waste copper-tin clad steel wire, characterized in that: The specific process of the method is as follows: (1) smelting and refining the recovered peeled waste copper-tin clad steel wire; (2) according to the furnace composition analysis results of the peeled waste copper-tin clad steel wire and the need to add copper and / or tin for further smelting, and then using a water atomization method to obtain a pre-alloyed powder; (3) drying the pre-alloyed powder obtained in step (2) to obtain powder A; (4) adding the powder A obtained in step (3) to copper oxide powder, mixing well and then reducing; (5) The powder obtained after reduction is crushed and sieved to obtain powder B required for powder metallurgy oil-containing bearings; (6) The powder B obtained in step (5) is molded to obtain an oil-containing bearing green body, and then sintered to obtain an oil-containing bearing product.

2. The method according to claim 1, characterized in that: In step (1), after all the waste copper-tin clad steel wires are completely melted after smelting, a refining agent is added for refining, wherein the refining agent is composed of dry aluminum carbonate, magnesium carbonate, calcium carbonate and Al 10 Si alloy particles, wherein aluminum carbonate accounts for 20-30% of the total mass, calcium carbonate accounts for 20-40%, magnesium carbonate accounts for 5-10%, and Al10Si alloy accounts for 20-30%.

3. The method according to claim 2, characterized in that: The amount of the refining agent added is 0.5-1.5% of the mass of the peeled waste copper-tin clad steel wire.

4. The method according to claim 1, characterized in that: In step (2), after copper and / or tin are added to the melt, the mass percentage of copper is 10-25% (preferably 15-20%), and the mass percentage of tin is 9-12%.

5. The method according to claim 1, characterized in that: In step (2), the particle size of the water atomized powder is controlled at -325 mesh and the proportion of the powder is greater than 50%.

6. The method according to claim 1, characterized in that: In step (4), the amount of copper oxide powder added is 1 to 2% of the mass of powder A.

7. The method according to claim 1 to 6, characterized in that: In step (4), copper powder is further added to make the total copper content in the powder be 15-20%.

8. The method according to claim 1, characterized in that: In step (4), the reducing atmosphere is an ammonia decomposition atmosphere, and the reducing time is 30-90 minutes.

9. The method according to claim 1, characterized in that: The bulk ratio of the powder B obtained after crushing and sieving in step (5) is 1.8 to 2.2 g cm -3 , -325 mesh powder accounts for no less than 30%.

10. The method according to claim 1, characterized in that: In step (6), the relative density of the compression molding is 75-80%; the sintering temperature is 850-900°C, the sintering atmosphere is ammonia decomposition gas, and the sintering time is 40-80 minutes.

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