Method for crushing waste hard metal

Abstract

The application discloses a kind of waste hard alloy breaking methods, comprising the following steps: providing waste hard alloy;-150 ℃ below liquid inert cooling medium is introduced into the waste hard alloy to cool down;After the waste hard alloy after cooling is immersed in electrolyte solution, it is taken out after sufficient soaking and dried;The waste hard alloy after drying is mechanically broken down.The waste hard alloy breaking method of the application is cooled down by introducing-150 ℃ below liquid inert cooling medium into the waste hard alloy, so that the waste hard alloy is broken due to rapid cooling, then the waste hard alloy after cooling is immersed in electrolyte solution, electrolyte solution is immersed in the crack of waste hard alloy, and particles adhering to the crack of waste hard alloy are formed after drying, so that the waste hard alloy is more easily broken down in the mechanical breaking process.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of cemented carbide recycling, in particular to a waste cemented carbide crushing method. BACKGROUND

[0002] Cemented carbide is an alloy material made of refractory metal hard compound and binder metal through powder metallurgy process, which has a series of excellent properties such as high hardness, wear resistance, good strength and toughness, heat resistance, corrosion resistance, etc. In particular, its high hardness and wear resistance remain basically unchanged even at a temperature of 500℃, and it still has very high hardness at 1000℃. Cemented carbide is widely used as a tool material, such as turning tool, milling cutter, planer tool, drill bit, boring tool, etc., for cutting cast iron, non-ferrous metal, plastic, chemical fiber, graphite, glass, stone and ordinary steel, and can also be used to cut heat-resistant steel, stainless steel, high manganese steel, tool steel and other difficult-to-machine materials.

[0003] Cemented carbide is usually made of tungsten carbide and rare metal cobalt as main raw materials, which has very high recycling value. Therefore, after being discarded, cemented carbide devices are usually recycled and reused. The main methods for recycling waste cemented carbide include zinc melting method and electrochemical selective electrolysis method. However, the above-mentioned methods for recycling waste cemented carbide all need to crush the waste cemented carbide.

[0004] The traditional method for crushing waste cemented carbide is mechanical crushing. However, waste cemented carbide has the characteristics of high temperature resistance and wear resistance, and it is not easy to crush itself, especially for larger size waste cemented carbide, which is more difficult to crush, and it is not easy to crush fully in the crushing process, which is not convenient for subsequent recycling. SUMMARY

[0005] Therefore, it is necessary to provide a waste cemented carbide crushing method which can solve the above-mentioned problems.

[0006] A waste cemented carbide crushing method, comprising the following steps:

[0007] Providing waste cemented carbide;

[0008] Passing liquid inert cold medium below-150℃ into the waste cemented carbide to reduce the temperature;

[0009] Immersion of the waste cemented carbide after temperature reduction into an electrolyte solution, and taking out and drying after sufficient soaking;

[0010] Mechanically crushing the waste cemented carbide after drying.

[0011] In one embodiment, in the operation of passing liquid inert cold medium below-150℃ into the waste cemented carbide to reduce the temperature, the temperature of the waste cemented carbide is reduced from 20℃-40℃ to 0℃-10℃.

[0012] In one embodiment, the operation of immersing the cooled waste hard alloy into the electrolyte solution has a concentration of 5wt% to 35wt% and a temperature of 0°C to 40°C.

[0013] In one embodiment, the operation of immersing the cooled waste hard alloy into the electrolyte solution has a concentration of 5wt% to 35wt% and a temperature of 0°C to 40°C.

[0014] In one embodiment, the operation of immersing the cooled waste hard alloy into the electrolyte solution has a concentration of 5wt% to 35wt% and a temperature of 0°C to 40°C.

[0015] In one embodiment, the operation of immersing the cooled waste hard alloy into the electrolyte solution has a concentration of 5wt% to 35wt% and a temperature of 0°C to 40°C.

[0016] In one embodiment, the electrolyte solution is a sodium chloride solution or a calcium chloride solution.

[0017] In one embodiment, the sodium chloride solution has a concentration of 10wt% and a temperature of 10°C.

[0018] In one embodiment, the liquid inert cold medium is liquid nitrogen.

[0019] The waste hard alloy crushing method of the present application cools the waste hard alloy by passing a liquid inert cold medium below -150°C through the waste hard alloy, causing the waste hard alloy to crack due to rapid cooling, then immersing the cooled waste hard alloy into an electrolyte solution, which penetrates into the cracks of the waste hard alloy, and after drying, forms particles adhering to the cracks of the waste hard alloy, thereby making the waste hard alloy easier to crush during mechanical crushing.

[0020] Compared with the traditional direct mechanical crushing method, the waste hard alloy crushing method of the present application is more complete in crushing the waste hard alloy during crushing, and is convenient for subsequent recycling.

[0021] In addition, the waste hard alloy after calcination is preliminarily cooled by the liquid inert cold medium, and then the waste hard alloy is secondarily cooled by the electrolyte solution, and through the combination of high-temperature treatment and low-temperature natural cooling and mechanical crushing, the crushing efficiency of the waste hard alloy can be improved, the waste hard alloy is fully crushed, and small-particle-size crushed materials are obtained, which is helpful to improve the efficiency of subsequent recycling.

[0022] Compared with the mode of cooling the waste hard alloy after calcination by the liquid inert cold medium once, the second cooling mode adopted in the application uses less liquid inert cold medium, and can reduce part of the cost.

[0023] Meanwhile, compared with the secondary cooling by water, the secondary cooling by the electrolyte solution has the following advantages: 1, the specific heat capacity of the electrolyte solution is higher than that of water, which can absorb more heat, and can avoid the evaporation of the electrolyte solution and the multiple replenishment of the electrolyte solution; 2, the freezing point of the electrolyte solution is lower than that of water, and the freezing point of the electrolyte solution is lower than that of ordinary water when frozen, and the temperature of the electrolyte solution can be reduced to below zero, while water will freeze at zero, and the use of the electrolyte solution can also prevent the water from freezing when the temperature of the liquid inert cold medium is reduced to 0℃, which affects the next use; 3, the thermal conductivity of the electrolyte solution is higher than that of pure water, which means that the heat conduction speed of the electrolyte solution may be faster under the same temperature and pressure conditions, so that the heat can be conducted from the surface of the waste hard alloy to the inside of the electrolyte solution, thereby accelerating the cooling process and preventing oxidation. BRIEF DESCRIPTION OF DRAWINGS

[0024] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, the drawings in the following description only constitute some embodiments of the present application, and for those skilled in the art, other drawings can also be obtained without creative labor.

[0025] Among them:

[0026] Figure 1 It is a flow chart of the crushing method of the waste hard alloy of an embodiment.

[0027] Figure 2 It is a flow chart of the crushing method of the waste hard alloy of another embodiment. DETAILED DESCRIPTION

[0028] With reference to the drawings of the embodiments of the present application, the technical solutions in the embodiments of the present application will be described clearly and completely. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments of the present application, all the other embodiments obtained by a person of ordinary skill in the art without creative work fall within the protection scope of the present application.

[0029] In combination with Figure 1 The present application discloses a method for crushing waste hard alloy, comprising the following steps:

[0030] S110, providing waste hard alloy.

[0031] S120, passing liquid inert cold medium below-150℃ into the waste hard alloy to reduce temperature.

[0032] Preferably, in the embodiment, in the operation of passing liquid inert cold medium below-150℃ into the waste hard alloy to reduce temperature, the temperature of the waste hard alloy is reduced from 20℃-40℃ to 0℃-10℃.

[0033] Specifically, in the embodiment, the liquid inert cold medium is liquid nitrogen. Generally, the temperature of the liquid nitrogen is-196℃.

[0034] S130, immersing the waste hard alloy after temperature reduction into electrolyte solution, and taking out after sufficient soaking and drying.

[0035] Preferably, in S130, the concentration of the electrolyte solution is 5wt%-35wt%, and the temperature of the electrolyte solution is 0℃-40℃.

[0036] Specifically, in the embodiment, the electrolyte solution is sodium chloride solution or calcium chloride solution.

[0037] Specifically, in the embodiment, the concentration of the sodium chloride solution is 10wt%, and the concentration of the calcium chloride solution is 30wt%.

[0038] It is particularly pointed out that the minimum freezing temperature of the calcium chloride solution with the concentration of 30wt% can reach minus 55℃.

[0039] S140, mechanically crushing the waste hard alloy after drying.

[0040] In the embodiment, the press machine can be used to mechanically crush the waste hard alloy after drying.

[0041] The waste hard alloy crushing method of the present application can make the waste hard alloy break due to rapid cooling by passing the liquid inert cold medium below -150 DEG C into the waste hard alloy, then immerse the cooled waste hard alloy into the electrolyte solution, the electrolyte solution is immersed into the crack of the waste hard alloy, and the particles adhered in the crack of the waste hard alloy are formed after drying, so that the waste hard alloy is more easily broken in the mechanical crushing process.

[0042] Compared with the traditional direct mechanical crushing method, the waste hard alloy crushing method of the present application can make the waste hard alloy more fully broken in the process of crushing the waste hard alloy, and is convenient for subsequent recycling.

[0043] In combination Figure 2 The waste hard alloy crushing method of another embodiment is disclosed, comprising the following steps:

[0044] S210, providing the waste hard alloy.

[0045] S220, calcining the waste hard alloy at 200 DEG C to 1000 DEG C for 1h to 6h.

[0046] In the present embodiment, the waste hard alloy can be placed in a natural gas trolley furnace to realize calcination.

[0047] Specifically, the calcination time can be 2h.

[0048] S230, passing the liquid inert cold medium below -150 DEG C into the calcined waste hard alloy to cool.

[0049] Preferably, in the operation of passing the liquid inert cold medium below -150 DEG C into the waste hard alloy to cool, the temperature of the waste hard alloy is reduced from 200 DEG C to 1000 DEG C to 80 DEG C to 120 DEG C.

[0050] Specifically, in the present embodiment, the liquid inert cold medium is liquid nitrogen. Generally, the temperature of the liquid nitrogen is -196 DEG C.

[0051] S240, immerse the cooled waste hard alloy into the electrolyte solution, and take out and dry after sufficient soaking.

[0052] Preferably, in S240, the concentration of the electrolyte solution is 5wt% to 35wt%, and the temperature of the electrolyte solution is 0 DEG C to 40 DEG C.

[0053] Specifically, in the present embodiment, the electrolyte solution is sodium chloride solution or calcium chloride solution.

[0054] Specifically, in the present embodiment, the concentration of the sodium chloride solution is 10wt%, and the concentration of the calcium chloride solution is 30wt%.

[0055] It should be particularly pointed out that the minimum freezing temperature of the calcium chloride solution with a concentration of 30wt% can reach minus 55℃.

[0056] S250, mechanically crushing the dried waste hard alloy.

[0057] In this embodiment, a press machine can be used to mechanically crush the dried waste hard alloy.

[0058] The waste hard alloy crushing method of the present application cools the waste hard alloy by passing a liquid inert cold medium below -150℃ into the waste hard alloy, so that the waste hard alloy is broken due to rapid cooling, and then the cooled waste hard alloy is immersed in an electrolyte solution, the electrolyte solution is immersed in the cracks of the waste hard alloy, and after drying, particles are formed attached to the cracks of the waste hard alloy, so that the waste hard alloy is more easily broken during mechanical crushing.

[0059] Compared with the traditional direct mechanical crushing method, the waste hard alloy crushing method of the present application is more fully broken during the crushing of the waste hard alloy, which is convenient for subsequent recycling.

[0060] In addition, by using a liquid inert cold medium to preliminarily cool the calcined waste hard alloy, and then using an electrolyte solution to secondarily cool the waste hard alloy, through the means of high-temperature treatment + low-temperature cold breaking combined with mechanical crushing, the crushing efficiency of the waste hard alloy can be improved, the waste hard alloy is fully broken, and small-particle-size crushed materials are obtained, which helps to improve the efficiency of subsequent recycling.

[0061] Compared with the method of using a liquid inert cold medium to cool the calcined waste hard alloy once, the secondary cooling method used in the present application uses less liquid inert cold medium, which can reduce part of the cost.

[0062] At the same time, compared with secondary cooling with water, secondary cooling with an electrolyte solution has the following advantages: 1. The specific heat capacity of the electrolyte solution is higher than that of water, which can absorb more heat, and can avoid the evaporation of a large amount of electrolyte solution and the repeated replenishment of the electrolyte solution; 2. The freezing point of the electrolyte solution is lower than that of water, so the freezing point of the electrolyte solution is lower than that of ordinary water when frozen, and the temperature of the electrolyte solution can be reduced to below zero, while water will freeze at zero, so the use of the electrolyte solution can prevent the water from freezing when the temperature of the liquid inert cold medium is too low and the temperature of the water is reduced to 0℃, which affects the next use; 3. The thermal conductivity of the electrolyte solution is higher than that of pure water, which means that under the same temperature and pressure conditions, the heat conduction speed of the electrolyte solution may be faster, so the heat can be conducted from the surface of the waste hard alloy to the inside of the electrolyte solution more quickly, thereby accelerating the cooling process and preventing oxidation.

[0063] The following is a specific example.

[0064] In the following examples, the waste hard alloy is a hard alloy roller ring with a diameter of 10 cm to 40 cm.

[0065] Example 1

[0066] Take the waste hard alloy, slowly pass liquid nitrogen into the waste hard alloy through the liquid nitrogen supply pipe at room temperature to cool the waste hard alloy to 30°C, then immerse the waste hard alloy in a 10wt% sodium chloride solution with a temperature of 10°C to cool to 20°C, then take out and dry, and crush on a press with a nominal pressure of 1500-3000 kN, a slide block stroke of 300-600 mm, and a stroke frequency of 20-40 times / min.

[0067] Example 2

[0068] Take the waste hard alloy, place it in a natural gas trolley furnace, calcine at 800°C for 2h, then slowly pass liquid nitrogen into the waste hard alloy through the liquid nitrogen supply pipe to cool the waste hard alloy to 100°C, then immerse the waste hard alloy in a 10wt% sodium chloride solution with a temperature of 10°C to cool to 20°C, then take out and dry, and crush on a press with a nominal pressure of 1500-3000 kN, a slide block stroke of 300-600 mm, and a stroke frequency of 20-40 times / min.

[0069] Comparative Example 1

[0070] Take the waste hard alloy and crush it on a press with a nominal pressure of 1500-3000 kN, a slide block stroke of 300-600 mm, and a stroke frequency of 20-40 times / min.

[0071] Comparative Example 2

[0072] Take the waste hard alloy, place it in a natural gas trolley furnace, calcine at 800°C for 2h, then slowly pass liquid nitrogen into the waste hard alloy through the liquid nitrogen supply pipe to cool the waste hard alloy to 100°C, then immerse the waste hard alloy in water with a temperature of 10°C to cool to 20°C, then take out and dry, and crush on a press with a nominal pressure of 1500-3000 kN, a slide block stroke of 300-600 mm, and a stroke frequency of 20-40 times / min.

[0073] Test Example

[0074] The waste hard alloy pieces obtained by crushing the waste hard alloy in Examples 1-3 and Comparative Example 1 were tested, and the crushing efficiency was calculated, and the specific results are shown in the following Table 1.

[0075] The crushing efficiency refers to the proportion of the material actually crushed after the material is crushed by the press. The calculation formula is: crushing efficiency = actual crushing amount / feeding amount, wherein the actual crushing amount refers to the amount of material passing through the screen, and the feeding amount refers to the amount of material input into the feeding port of the press, usually expressed in percentage.

[0076] Table 1

[0077] Example 1 Example 2 Comparative Example 1 Comparative Example 2 Average diameter 4-5 cm 2-3 cm 5-6 cm 4.5-5.5 cm Crushing efficiency 70％～75％ 95％～98％ 30％～40％ 60％～65％ Secondary cooling time - 45 min - 60 min

[0078] As can be seen from Table 1, the crushing efficiency of the method in Examples 1 and 2 is obviously better than that of Comparative Examples 1 and 2, and the crushing efficiency of the method in Example 2 is obviously better than that in Example 1; in addition, the secondary cooling in Example 2 using a 10wt% sodium chloride solution only takes 45 minutes, while the secondary cooling in Comparative Example 2 using water takes 60 minutes, and the secondary cooling time in Example 2 is shortened by 25%, which can save the overall processing time and improve the recovery work efficiency.

[0079] The above-described examples only express several embodiments of the present application, and the description is more specific and detailed, but it should not be understood as limiting the scope of the patent application. It should be pointed out that for ordinary skilled in the art, without departing from the concept of the present application, a number of modifications and improvements can be made, which are all within the scope of the present application. Therefore, the protection scope of the present application patent should be subject to the appended claims.

Claims

1. A method for crushing waste cemented carbide, characterized in that, Includes the following steps: Provide scrap cemented carbide; The waste cemented carbide is calcined at 200℃~1000℃ for 1h~6h; A liquid inert cooling medium at -150°C or below is introduced into the waste cemented carbide to lower its temperature, thereby reducing the temperature of the waste cemented carbide from 200°C to 1000°C to 80°C to 120°C. The cooled waste cemented carbide is immersed in a sodium chloride solution or calcium chloride solution with a concentration of 5wt%~35wt% and a temperature of 0℃~40℃. After being fully immersed, it is taken out and dried. The dried waste cemented carbide is mechanically crushed.

2. The method for crushing waste cemented carbide according to claim 1, characterized in that, The concentration of the sodium chloride solution is 10 wt%, and the temperature of the sodium chloride solution is 10 °C.

3. The method for crushing waste cemented carbide according to claim 1, characterized in that, The liquid inert cooling medium is liquid nitrogen.

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