CN111426192A

CN111426192A - Method for recycling waste hard alloy roll collars

Info

Publication number: CN111426192A
Application number: CN202010287044.2A
Authority: CN
Inventors: 赵勇; 刘和平
Original assignee: Hunan Tianyi Hi Tech Material Manufacture Co ltd
Current assignee: Hunan Tianyi Hi Tech Material Manufacture Co ltd
Priority date: 2020-04-13
Filing date: 2020-04-13
Publication date: 2020-07-17

Abstract

The invention discloses a method for recycling waste hard alloy roll collars, which comprises the steps of carrying out ultrasonic cleaning on the roll collars, stacking graphite boats with integral waste hard alloy roll collars in a heating furnace layer by layer, and adding the graphite boats after vacuumizingThe flow rate of the hot furnace is 0.3-2.0 m³Heating to 2000-2200 ℃ with nitrogen, preserving heat for 1-10 h, and cooling. And (3) knocking the mixture into fragments less than or equal to 3cm by using an air hammer, and putting the fragments into a ball mill for ball milling for 1-3 h, wherein the ball-material ratio is (4-8): 1, the diameter of the round ball is 10-50 mm. And classifying the ball-milled screened materials by using a double screen, wherein fine screened materials with the grain size of less than or equal to 180 meshes are used as the hard alloy roll collar material with low bonding phase content, medium screened materials with the grain size of more than 120 meshes are used as the hard alloy roll collar material with high bonding phase content, and the screened materials cannot be reprocessed. The heating furnace with a large heating area and the graphite boat which is independently researched and developed are adopted, so that the whole treatment can be carried out, the production cost is saved, the use and the replacement are convenient, and the practical value is high.

Description

Method for recycling waste hard alloy roll collars

Technical Field

The invention relates to a method for recycling waste materials, in particular to a method for recycling waste hard alloy roll collars, which are applied to a high-speed bar and wire rolling mill frame and cannot be reused after the waste materials reach the scrapped size.

Background

In the production line of high-speed and high-efficiency production of screw-thread steel or other kinds of steel bar and wire of large and medium-sized iron and steel enterprises, the hard alloy roll collar is the best and most commonly used roll at present, and is matched with a large number of pre-rolling mills and finishing mill frames, and the most important characteristics are good impact resistance and excellent wear resistance, and the hard alloy roll collar basically replaces cast steel, cast iron and high-speed steel rolls.

However, the hard alloy roll collar is made of expensive tungsten carbide (WC), nickel (Ni), cobalt (Co) and other precious metals by a high-cost powder metallurgy process, and the hard alloy roll collar has extremely high production cost due to poor use working conditions, raw materials and high grade and quality requirements. How to recycle or reuse the waste hard alloy roll collars is a difficult problem to be solved for hard alloy roll collar production enterprises or use units, and is a great pain point and demand of the hard alloy industry.

The method has the main problems that ① hard alloy roll collars are extremely strong in impact resistance and high in crushing cost, a water quenching and impact crushing method which circulates for many times is adopted, production efficiency is low, fragments are large, oxidation is serious, impurities are introduced, labor intensity is high, tungsten carbide on the surfaces of the fragments is stripped through ball milling for ② times, tungsten carbide grains are refined, impurities such as titanium and iron are introduced, impurity components are high, grain size is poor, grain size distribution is poor, ③ production cost is high, yield is low, pollution is high, a zinc melting method is adopted, the method is the next choice of a waste hard alloy roll collar treatment method and is rarely used at present, the method has the problems that ① must be crushed firstly, cost is high, a water quenching and impact crushing method which circulates for many times is adopted, production efficiency is low, the fragments are large, impurities are introduced, oxidation is serious, a ② zinc melting and ball milling process can only treat a surface layer, the zinc melting and surface layer melting zinc and silicon are melted, the ball milling method is low in production cost, and high in production cost, and the production cost is high in ③.

Disclosure of Invention

The invention aims to provide an innovative method for recycling waste hard alloy roll collars, which can recycle the recycled materials of the waste hard alloy roll collars after the waste hard alloy roll collars are recycled to meet the quality requirement of manufacturing new hard alloy roll collars and the produced hard alloy roll collars can recycle the waste hard alloy roll collars to meet the use requirement of high-speed rods and wires.

In order to achieve the purpose, the invention adopts the technical scheme that: the method for recycling the waste hard alloy roll collars comprises the steps of ultrasonic cleaning of the roll collars, loading, high-temperature treatment, surface cleaning, mechanical crushing, ball milling, sieving, oxidation treatment, sintering embrittlement, re-crushing and sieving, recycling, and chemical examination and warehousing.

And ultrasonically cleaning the inner surface and the outer surface of the waste hard alloy roll collar to remove oil on the inner surface and the outer surface.

And (3) loading the waste hard alloy roll collar subjected to ultrasonic cleaning into a graphite boat. The process is as follows: the method comprises the following steps of arranging a cushion layer at the bottom of an inner cavity of a graphite boat, placing a first isolation plate on the upper surface of the cushion layer, placing a waste hard alloy roll collar to be treated on the first isolation plate, and enabling the axial center line of the waste hard alloy roll collar to coincide with the axial center line of the graphite boat during placement. And a second isolation plate is arranged on the outer side surface of the waste hard alloy roll collar to isolate the waste hard alloy roll collar from the graphite boat. And a barrier layer is arranged between the graphite boat and the second isolation plate, and carbon black powder or graphite powder is selected as the barrier layer. The height difference between the barrier layer and the top end of the waste hard alloy roll collar is W₂Taking W₂And = 10-30 mm. Wherein the bed course is the carbon black powder of 20 ~ 30mm thickness or graphite powder layer, and first isolation board and second isolation board all select for use the cardboard that thickness is 1 ~ 4 mm.

Stacking the graphite boat with the waste integral hard alloy roll collars layer by layer into a heating furnace, wherein a gap W is formed between the upper surface of the next layer of waste hard alloy roll collars and the graphite boat with the waste hard alloy roll collars to be treated₁Taking W₁=10～40mm。

Closing the furnace door of the heating furnace stacked with the graphite boats with the number more than or equal to 1, and vacuumizing. Introducing nitrogen into the vacuumized heating furnace to atmospheric pressure, wherein the flow rate of the nitrogen is controlled to be 0.3-2.0 m³H is used as the reference value. And (3) rapidly heating the heating furnace to 2000-2200 ℃, preserving the heat for 1-10 hours, and cooling along with the furnace.

Taking out the expanded porous waste hard alloy roll collars from the heating furnace after high-temperature treatment, knocking the roll collars into fragments with the particle size of less than or equal to 3cm by using an air hammer, putting the fragments into a ball mill for ball milling, wherein the diameter of a ball in the ball mill is equal to 10-50 mm, and the ball-material ratio is controlled to be (4-8): 1, ball milling for 1-3 h, and ball-milling the broken blocks into sieved materials.

Sieving the ball-milled sieving material by using a double-screen to obtain powder material, and using the powder material in a grading way: the fine sieve material with the grain size of less than or equal to 180 meshes is used as the hard alloy roll collar material with low bonding phase content, the medium sieve material with the grain size of less than or equal to 120 meshes and more than 180 meshes is used as the hard alloy roll collar material with high bonding phase content, and the coarse material with the grain size of more than 120 meshes and which can not pass through the screen mesh is subjected to oxidation, high-temperature treatment or electrolysis treatment. The content of the bonding phase is (Co + Ni + Cr) Wt%.

The method for recycling the waste hard alloy roll collars has the technical effects that ① the method adopts a medium-frequency induction vacuum/atmosphere heating furnace with a large heating area, a temperature measuring system is changed into optical and thermocouple temperature measurement on the basis of the traditional medium-frequency induction heating furnace, high-oxidation-resistance ceramics are used for electrode protection, an assembled graphite boat is made of high-strength graphite to form a closed heating area, ② the assembled graphite boat which is independently developed is used for bearing the integral waste hard alloy roll collars to be treated at high temperature, the use is convenient, the cost of the graphite boat is reduced, ③ the boat loading mode of the roll collars is improved, a plurality of waste hard alloy roll collars to be treated can be loaded in the heating furnace, and the treatment cost is saved.

Drawings

FIG. 1 is a schematic view showing the charging of a graphite boat loaded with waste cemented carbide collars to be treated, stacked layer by layer in a heating furnace.

Fig. 2 is an external (three-dimensional) view of the graphite boat used.

Detailed Description

The following describes embodiments of the present invention in further detail with reference to the accompanying drawings.

The invention relates to a method for recycling waste hard alloy roll collars, which is characterized in that waste hard alloy roll collars are processed in a series to prepare reclaimed material powder, and the qualified powder is recycled to prepare new hard alloy roll collars by adopting a powder metallurgy method after the reclaimed material powder is qualified in test. The method comprises the following steps: the method comprises the following steps of ultrasonically cleaning waste (scrapped) hard alloy roll collars 2, loading the cleaned waste hard alloy roll collars 2 to be subjected to high-temperature treatment into a boat, performing high-temperature treatment, removing dirt on the surface, mechanically crushing and knocking the surface into fragments with the particle size of less than or equal to 3cm, ball-milling the fragments into powder in a large-diameter ball mill, sieving the powder to obtain the required recovered powder, and testing and warehousing the powder for later use.

As shown in fig. 2, a graphite boat 1 is an independently developed assembled graphite boat, and is specially used for carrying a waste hard alloy roll collar 2 to be subjected to high-temperature treatment. If the graphite boat 1 is damaged due to boat adhesion in the high-temperature treatment process, only the corresponding module needs to be replaced, and the whole graphite boat is not required to be replaced, so that the graphite boat is convenient to use, and the treatment cost is reduced.

Fig. 1 shows a graphite boat 1 loaded with waste (scrap) cemented carbide collars 2 after ultrasonic cleaning in a partially cross-sectional view in a state where they are stacked one on another in a heating furnace which may be a medium frequency induction vacuum atmosphere furnace having a large heating zone. Firstly, arranging a cushion layer 3 at the bottom of a graphite boat 1, wherein the cushion layer 3 is a layer of carbon black/graphite powder which is scattered at the bottom of an inner cavity of the graphite boat 1 and has the thickness of 20-30 mm. First isolation board 4 has been placed at the upper surface of bed course 3, 1 ~ 4mm thickness's cardboard can be chooseed for use to first isolation board 4, places the (cylinder type) old and useless carbide collars 2 that awaits treatment at first isolation board 4 upper surface. When the waste hard alloy roll collar 2 is placed, the axial center line of the waste hard alloy roll collar 2 is superposed with the axial center line of the graphite boat 1, and two-line integration is realized.

As shown in fig. 1, a second isolation plate 6 is disposed on an outer side surface of the waste hard alloy roll collar 2, the second isolation plate 6 may be made of a paper board with a thickness of 1-4 mm, and the second isolation plate 6 is used for isolating the waste hard alloy roll collar 2 from the graphite boat 1. There is barrier layer 5 between graphite boat 1 and second isolation board 6, barrier layer 5 is filled the compaction with graphite powder or charcoal black powder and forms, and its effect lies in preventing under the high temperature old and useless carbide collars 2 part liquefaction lead to bonding graphite boat 1, because of this kind bonds can harm the graphite plate (being the graphite module) on graphite boat 1. The height difference W is formed between the barrier layer 5 between the second isolation plate 6 and the graphite boat 1 and the top end of the waste hard alloy roll collar 2₂Taking W₂=10～30mm。

As shown in figure 1, the graphite boat 1 with the waste hard alloy roll collars 2 is stacked into the hearth of the heating furnace 7 layer by layer, and a gap W is formed between the upper surface of the next layer of waste hard alloy roll collars 2 and the bottom plate of the graphite boat 1 with the waste hard alloy roll collars 2 to be treated₁Taking W₁And the grain size is 10-40 mm, so that the phenomenon that the waste hard alloy roll collar 2 expands in volume at high temperature and is not bonded with other graphite boats is avoided.

The furnace door of the heating furnace 7 with the number of the graphite boats 1 more than or equal to 1 is closed and vacuumized. Introducing nitrogen (N) to the vacuumized heating furnace 7 to atmospheric pressure, wherein the flow rate of the nitrogen is 0.3-2.0 m³H is used as the reference value. The nitrogen flow rate is related to the sealing performance of the heating furnace door, and the surface of the waste hard alloy roll collar 2 after treatment is preferably metallic luster, and does not have yellow green and other colors.

And after introducing nitrogen to atmospheric pressure, rapidly heating the heating furnace 7 to 2000-2200 ℃, preserving heat for 1-10 hours, and cooling along with the furnace. The temperature detection in the heating furnace 7 adopts optics and a thermocouple for temperature measurement, high-oxidation-resistance ceramics are used for electrode protection, and the graphite boat 1 made of high-strength graphite is used as a closed heating area, so that the phenomenon that the furnace body of the heating furnace 7 is polluted by volatilization of nickel (Ni) and cobalt (Co) at high temperature (such as 2000-2200 ℃) can be prevented, double heating of the waste hard alloy roll collar 2 and the furnace hearth can be realized, the heating speed is ensured, and the heat transfer is rapid. Most importantly, after the heating furnace 7 with a large hearth is adopted, the whole waste hard alloy roll collar 2 to be subjected to high-temperature heating treatment can be directly loaded in the independently developed graphite boat 1 without being crushed in advance, and the power consumption can be greatly reduced. For example, the power consumption is reduced to about 3Kw.h/kg from 6-10 Kw.h/kg of the carbon tube furnace. The treatment temperature of the waste hard alloy roll collar 2 to be treated at high temperature is slightly different according to different grades. Generally, the waste cemented carbide roll collars 2 with high binder phase content have low treatment temperature (such as about 2000 ℃) and long treatment time (such as 4-10 hours). The content of the bonding phase is (Co + Ni + Cr) Wt%.

Taking the expanded and porous waste hard alloy roll collar 2 subjected to high-temperature treatment (2000-2200 ℃/1-10 h) out of the heating furnace to clean the surface (such as removing graphite or carbon black ash on the surface), knocking the roll collar into fragments (such as spheres and particles with the particle size of less than or equal to 3 cm) by using an air hammer, putting the fragments into a (large-diameter) ball mill, wherein hard alloy spheres with the diameter of 10-50 mm are adopted as the spheres in the ball mill, and the ball-material ratio is kept to be (4-8): 1, ball milling for 1-3 h, and ball-milling the broken blocks into sieved materials.

Sieving the sieved material subjected to ball milling by using a double screen to obtain powder material, and grading the powder material for different grades of hard alloy roll collars: the fine sieve with grain size less than or equal to 180 meshes is used as the hard alloy roll collar material with low bonding phase content, and the medium sieve with grain size between 120 meshes and 180 meshes is used as the hard alloy roll collar material with high bonding phase content. The low bonding phase content is (Co + Ni + Cr) less than 20% by mass, and the high bonding phase content is (Co + Ni + Cr) more than 20% by mass.

And (3) carrying out oxidation and high-temperature treatment on coarse materials with the particle size larger than 120 meshes and incapable of passing through the screen, namely placing the coarse materials in a muffle furnace, heating to 800-1000 ℃, and oxidizing for 1-2 hours. The surface oxidation is carried out without powdering the tungsten carbide crystal grains. The material to be treated by oxidation and high temperature treatment and the next batch of waste hard alloy roll collars to be treated can be put into a heating furnace together for high temperature treatment. In addition, coarse materials with the particle size of more than 120 meshes (such as the particle size of about 10 mm) which can not be sieved can be reprocessed by adopting the traditional electrolysis/zinc melting method, so that the interior of part of the materials is rich in holes, the content of bonding phase is high, tungsten carbide crystal grains are coarse, electrolysis/zinc melting stripping is very easy, the electrolysis efficiency is high, the electrolysis/zinc melting yield is also high, and passivation phenomenon is not easy to occur.

And (3) analyzing the components and the carbon content of the fine sieve material with the particle size of less than or equal to 180 meshes and the medium sieve material with the particle size of less than or equal to 120 meshes and more than 180 meshes, and packaging and warehousing for later use.

And (3) heating powder, granular materials and fine block materials (materials are sieved by a 120-mesh screen) with the particle size larger than 120 meshes in a muffle furnace under the atmospheric environment to 800-900 ℃, preserving heat for 0.5-1.0 h, pre-oxidizing the partial materials, cooling the partial materials along with the furnace, and then carrying out high-temperature treatment on the partial materials and the waste roll collar to be treated again. The oversize material after preoxidation and high-temperature treatment is easy to break because a large amount of (CoNi)3W3C and (CoNi)6W6C phases with extremely strong brittleness are generated in the particles, and a loose porous structure is reserved.

The pre-oxidized and high-temperature treated material blocks and particles are crushed, ball-milled and sieved together with the high-temperature treated waste hard alloy roll collars, and then the crushed and ball-milled waste hard alloy roll collars and the particles are separately used as production raw materials of the hard alloy roll collars according to whether the materials can pass through a 180-mesh screen and a 120-mesh screen.

The fine sieve material and the medium sieve material can be used for producing the hard alloy roll collar after being analyzed and measured by components and carbon, and the fine sieve material with the grain diameter less than or equal to 180 meshes is usually used for producing the hard alloy roll collar with the bonding phase content below 20 percent (Wt) (namely, the content of the low bonding phase) because the fine sieve material has better quality and relatively thinner grains, and the hard alloy roll collar can be produced according to the normal process by supplementing the lacking materials in the production process and adjusting the carbon content; the medium-sized material with the grain size of less than or equal to 120 meshes and more than 180 meshes is generally used for producing the hard alloy roll collar with high bonding phase mark, and a part (such as 0-50% by mass) of raw materials can be properly doped in the production process so as to improve the performance of the hard alloy roll collar.

The forming agent can be PEG, rubber or paraffin, but in order to improve the quality of pressed compact, PEG or rubber is best used as the forming agent.

The hard alloy roll collar produced by the fine screening material or the medium screening material has the following properties: density = 12.6-14.5 +/-0.05 g/cm³Hardness = 78-88 HRA, bending strength = 2100-2800 MPa, compressive strength = 3000-3400 MPa, steel passing amount = 700-8000 t (different grades, different rolling mill stands and different steel passing amounts are different), and bonding phase content (Co + Ni + Cr) = 10-30%.

Example 1

The waste hard alloy roll collar 2 is subjected to ultrasonic cleaning treatment and is integrally placed on a first isolation plate 4 in the inner cavity of the graphite boat 1. The graphite boat 1 loaded with the waste hard alloy roll collars 2 is stacked into a heating furnace 7 layer by layer. Closing the furnace door, introducing nitrogen into the vacuumized heating furnace 7 to atmospheric pressure, and controlling the flow of nitrogen at 0.6m³And h, heating to 2000 ℃, keeping the temperature for 4h, and cooling along with the furnace. Knocking the waste hard alloy roll collars 2 subjected to high-temperature treatment into fragments with the particle size of less than or equal to 3cm by using an air hammer, putting the fragments into a ball mill for ball milling, selecting balls with the diameter of 10-50 mm, and controlling the ball-to-material ratio to be 4: 1, ball milling time is 3 h. Sieving the sieved material after ball milling by using a double-screen, taking medium-fine sieve material with the particle size of less than or equal to 120 meshes and more than 180 meshes, and recycling the medium-fine sieve material to manufacture the hard alloy roll collar, wherein the material density of the hard alloy roll collar is 13.5g/cm³Hardness =82HRA, bending strength =2280MPa, compressive strength =3120MPa, bonding phase content (Co + Ni + Cr) Wt% =20, and the steel passing amount reaches 1342t, and the use requirement is met.

Example 2

The waste hard alloy roll collar 2 is subjected to ultrasonic cleaning treatment and is integrally placed on a first isolation plate 4 in the inner cavity of the graphite boat 1. Stacking the graphite boat 1 with the waste hard alloy roll collars 2 into a heating furnace 7 layer by layer, and simultaneously placing the oversize granules of a 120-mesh screen mesh subjected to high-temperature treatment and crushing and sieving into granulesThe inner hole of the roller ring is closed, the furnace door is closed, nitrogen is introduced into the evacuated heating furnace 7 to atmospheric pressure, the nitrogen flow is controlled at 1.1m3/h, the temperature is raised to 2200 ℃, and the temperature is kept for 2h to be cooled along with the furnace. Knocking the waste hard alloy roll collars 2 subjected to high-temperature treatment into fragments with the particle size of less than or equal to 3cm by using an air hammer, putting the fragments into a ball mill for ball milling, selecting balls with the diameter of 20-40 mm, and controlling the ball-to-material ratio to be 5: 1, the ball material time is 2 hours. Sieving the sieved material after ball milling by using a double-screen, taking fine sieve material with the particle size of less than or equal to 180 meshes, and recycling the fine sieve material to manufacture a hard alloy roll collar, wherein the material density of the hard alloy roll collar is 14.0g/cm³The hardness =84HRA, the bending strength =2410MPa, the compressive strength =3300MPa, the bonding phase content (Co + Ni + Cr) Wt% =15, and the steel passing amount reaches 3472t, thereby meeting the use requirements.

Claims

1. A method for recycling waste hard alloy roll collars comprises ultrasonic cleaning, boat loading, high-temperature treatment, surface cleaning, mechanical crushing, ball milling, sieving, recycling, and chemical examination and warehousing, and is characterized in that:

the inner surface and the outer surface of the waste hard alloy roll collar (2) are cleaned by ultrasonic waves, and oil substances are removed;

the waste hard alloy roll collar (2) cleaned by ultrasonic waves is arranged in a graphite boat (1): firstly, a cushion layer (3) is arranged at the bottom of an inner cavity of a graphite boat (1), a first isolation plate (4) is arranged on the upper surface of the cushion layer (3), and a waste hard alloy roll collar (2) is arranged on the first isolation plate (4); a second isolation plate (6) is arranged on the outer side surface of the waste hard alloy roll collar (2) to isolate the waste hard alloy roll collar (2) from the graphite boat (1); there is barrier layer (5) between graphite boat (1) and isolated board of second (6), there is difference in height W between barrier layer (5) and old and useless carbide collars (2) top₂Taking W₂=10～30mm；

Stacking the graphite boat (1) provided with the waste hard alloy roll collars (2) into a heating furnace (7) layer by layer, wherein the upper surface of the next layer of waste hard alloy roll collar (2) and the graphite boat (1) provided with the waste hard alloy roll collar (2) to be treated are arranged between the upper surface of the next layer of waste hard alloy roll collar (2) and the previous layer of graphite boat (1)Spacing W₁Taking W₁=10～40mm；

Closing furnace doors of the heating furnaces (7) stacked with the number of the graphite boats (1) being more than or equal to 1, and vacuumizing; introducing nitrogen into the vacuumized heating furnace (7) to atmospheric pressure, wherein the flow rate of the nitrogen is controlled to be 0.3-2.0 m³Heating the heating furnace (7) to 2000-2200 ℃, preserving the heat for 1-10 h, and cooling along with the furnace;

taking out the expanded porous waste hard alloy roll collar (2) from the heating furnace after high-temperature treatment, knocking the roll collar into fragments with the particle size of less than or equal to 3cm by using an air hammer, putting the fragments into a ball mill for ball milling, wherein the diameter of a ball in the ball mill is 10-50 mm, and the ball-material ratio is controlled to be (4-8): 1, ball milling for 1-3 h, and ball milling the fragments into sieved materials;

sieving the ball-milled sieving material by using a double-screen to obtain powder material, and using the powder material in a grading way: fine sieve materials with the particle size of less than or equal to 180 meshes are used as hard alloy roll collars with low bonding phase content, medium sieve materials with the particle size of less than or equal to 120 meshes and larger than 180 meshes are used as hard alloy roll collars with high bonding phase content, and coarse materials with the particle size of larger than 120 meshes and incapable of passing through a screen are subjected to oxidation and high-temperature treatment or electrolysis treatment;

the content of the bonding phase is (Co + Ni + Cr) Wt%;

and analyzing the components and the carbon content of the fine sieve material and the medium sieve material, packaging and warehousing.

2. The method for recycling the waste hard alloy roll collars according to claim 1, which is characterized in that: the cushion layer (3) at the bottom of the graphite boat (1) is carbon black powder/graphite powder which is spread at the bottom of an inner cavity of the graphite boat (1) and has the thickness of 20-30 mm, and the barrier layer (5) between the graphite boat (1) and the second isolation plate (6) is filled with the carbon black powder/graphite powder.

3. The method for recycling the waste hard alloy roll collars according to claim 1, which is characterized in that: the first isolation plate (4) placed on the upper surface of the cushion layer (3) and the second isolation plate (6) placed on the outer side surface of the waste hard alloy roll collar (2) are made of paperboards with the thickness of 1-4 mm.

4. The method for recycling the waste hard alloy roll collars according to claim 1, which is characterized in that: the axial center line of the waste hard alloy roll collar (2) placed on the upper surface of the first isolation plate (4) is superposed with the axial center line of the graphite boat (1).