Hard alloy recovery method

Abstract

The invention discloses a hard alloy recovery method which comprises the following steps: putting a hard alloy and zinc into a zinc smelting furnace, introducing a protective atmosphere to enable the pressure in the zinc smelting furnace to be 1.2-1.5 MPa, and heating and smelting to obtain a eutectic; carrying out vacuum distillation on the eutectic mixture to volatilize the zinc, so as to obtain a zinc melting product; and the zinc melting product is mechanically crushed to obtain zinc melting powder, the zinc melting efficiency can be improved, and the hard alloy obtained after zinc melting is easier to crush.

Description

Technical Field

[0001] The present invention relates to the technical field of cemented carbide resource recovery, and more specifically, to a cemented carbide recovery method. Background Art

[0002] Tungsten is a rare metal. With the increasing number of various tungsten products and the increasing mining volume, the original tungsten resource mineral reserves are becoming increasingly exhausted. Therefore, it is of great significance to recycle tungsten from tungsten-containing cemented carbide waste.

[0003] Cemented carbide is an alloy material made of hard compounds of refractory metals and bonding metals through powder metallurgy. Cemented carbide has high hardness, strength, wear resistance and corrosion resistance. It is known as the "industrial teeth" and is used to manufacture cutting tools, knives, cobalt tools and wear-resistant parts. It is widely used in military industry, aerospace, mechanical processing, metallurgy, oil drilling, mining tools, electronic communications, construction and other fields.

[0004] When recycling cemented carbide and preparing high-purity tungsten or tungsten carbide products, the cemented carbide needs to be crushed into particles first. The basic principle of zinc melting method for treating cemented carbide is that zinc and the bonding phase metal (such as cobalt, nickel, etc.) in cemented carbide can form a low melting point alloy, so that the bonding metal is separated from the cemented carbide and forms a eutectic alloy liquid with zinc, thereby destroying the structure of the cemented carbide, and the dense alloy becomes a loose hard phase skeleton, which is convenient for the subsequent mechanical crushing method to obtain zinc molten powder. Since zinc does not react chemically with the carbides of various refractory alloy metals, the vapor pressure of zinc at a certain temperature is much greater than the vapor pressure of the bonding phase such as cobalt, so that the zinc evaporates and is recycled. Therefore, the zinc melting method can effectively remove the bonding phase metal in the cemented carbide while retaining the original characteristics of the carbide powder.

[0005] However, the removal efficiency of the bonding phase by the existing zinc melting method is relatively low, which makes the subsequent crushing process difficult and the resulting alloy crushed particles are large in size, affecting the subsequent tungsten carbide recovery rate. Summary of the invention

[0006] The purpose of the present invention is to overcome the above-mentioned defects of the prior art, provide a method for recovering cemented carbide, improve the efficiency of zinc melting, and make the cemented carbide after zinc melting easier to break.

[0007] To achieve the above object, the technical solution of the present invention is as follows:

[0008] A method for recycling cemented carbide, comprising the following processes:

[0009] Put the hard alloy and zinc into a zinc melting furnace, introduce a protective atmosphere, make the pressure in the zinc melting furnace be 1.2MPa-1.5MPa, increase the temperature and melt to obtain a eutectic;

[0010] performing vacuum distillation on the eutectic to volatilize the zinc to obtain a zinc molten product;

[0011] The zinc melt product is mechanically crushed to obtain zinc melt powder.

[0012] Implementing the embodiments of the present invention will have the following beneficial effects:

[0013] The embodiment of the present invention pressurizes the zinc melting process to enhance the penetration of zinc into the cemented carbide, which not only improves the melting rate of the bonding phase, but also makes the zinc melting product more loose, so that the mechanical crushing process can obtain smaller zinc melting powder. DETAILED DESCRIPTION

[0014] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0015] The invention discloses a method for recycling cemented carbide, comprising the following process:

[0016] 1) Put the cemented carbide and zinc into a zinc melting furnace, introduce a protective atmosphere, make the pressure in the zinc melting furnace be 1.2MPa-1.5MPa, increase the temperature and melt to obtain a eutectic.

[0017] In the above technical solution, the zinc melting process is pressurized to enhance the penetration of zinc into the cemented carbide, which not only increases the melting rate of the bonding phase, but also makes the zinc melting product more loose, so that the mechanical crushing process can obtain smaller zinc melting powder.

[0018] In a specific embodiment, the mixing mass ratio of cemented carbide to zinc is 1:1-1:2, the smelting temperature is 500° C.-900° C., and the smelting time is 10 h-15 h.

[0019] In a specific embodiment, the protective atmosphere includes nitrogen and / or an inert gas.

[0020] 2) The eutectic is subjected to vacuum distillation to volatilize zinc to obtain a zinc molten product.

[0021] In a specific embodiment, the vacuum distillation temperature is 970° C. to 980° C., and the vacuum distillation time is 10 h to 20 h.

[0022] 3) Mechanically crushing and screening the zinc melt product to obtain zinc melt powder.

[0023] In a specific embodiment, the average particle size of the zinc molten powder is less than 0.18 mm, preferably 0.01 mm to 0.18 mm.

[0024] In a specific embodiment, the method for recycling cemented carbide further includes the following process:

[0025] 4) After acid leaching and solid-liquid separation of the zinc molten powder, oxidative roasting is carried out in air to convert tungsten into tungsten oxide to obtain an oxidation product.

[0026] In a specific embodiment, the temperature of the oxidation roasting is 500° C. to 900° C., and the time of the oxidation roasting is 1 h to 10 h.

[0027] 5) The oxidation product is subjected to alkaline leaching, and the tungsten oxide is dissolved by the alkali to obtain a soluble tungstate leachate.

[0028] In a specific embodiment, the alkali solution used for alkali leaching includes one or more of NaOH, Na2CO3, ammonia water, etc.

[0029] The temperature of the alkali leaching can be 90° C. to 100° C., and the time of the alkali leaching can be 2 h to 6 h.

[0030] The following are specific embodiments.

[0031] Example 1

[0032] 1) Take 100g of cemented carbide (W: 96.29wt%; Co: 1.80wt%; Ni: 1.77wt%), mix it with 150g of zinc and place it in a smelting furnace, introduce nitrogen protective gas, make the pressure in the furnace 1.2MPa, heat it to 850℃, react for 10h, then evacuate and continue to heat it to 960℃, react for 15h to obtain a zinc molten product.

[0033] 2) The zinc melt product is mechanically crushed to obtain zinc melt powder, and the average particle size of the zinc melt powder is 0.18 mm.

[0034] Example 2

[0035] 1) Take 100g of cemented carbide (W: 96.29wt%; Co: 1.80wt%; Ni: 1.77wt%), mix it with 150g of zinc and place it in a smelting furnace, introduce nitrogen protective gas, make the pressure in the furnace 1.5MPa, heat it to 850℃, react for 10h, then evacuate and continue to heat it to 960℃, react for 15h to obtain a zinc molten product.

[0036] 2) The zinc melt product is mechanically crushed to obtain zinc melt powder, and the average particle size of the zinc melt powder is 0.18 mm.

[0037] Comparative Example 1

[0038] The difference between Comparative Example 1 and Example 1 is that no pressure is applied, specifically as follows:

[0039] 1) Take 100g of cemented carbide (W: 96.29wt%; Co: 1.80wt%; Ni: 1.77wt%), mix it with 150g of zinc and place it in a smelting furnace, introduce nitrogen protective gas, make the pressure in the furnace 1MPa, raise the temperature to 850℃, react for 10h, then evacuate and continue to raise the temperature to 960℃, react for 15h to obtain a zinc molten product.

[0040] 2) The zinc melt product is mechanically crushed and sieved to obtain zinc melt powder, and the average particle size of the zinc melt powder is 0.25 mm.

[0041] Comparing Example 1 with Comparative Example 1, it can be seen that the method of the present invention can obtain a ground product with a smaller particle size, indicating that the zinc melting process is more complete.

[0042] The above-mentioned embodiments only express several implementation methods of the present invention, and the description thereof is relatively specific and detailed, but it cannot be understood as limiting the scope of the patent application. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A method for recycling cemented carbide, characterized in that: The process includes: Put the hard alloy and zinc into a zinc melting furnace, introduce a protective atmosphere, make the pressure in the zinc melting furnace be 1.2MPa-1.5MPa, increase the temperature and melt to obtain a eutectic; performing vacuum distillation on the eutectic to volatilize the zinc to obtain a zinc molten product; The zinc melt product is mechanically crushed and sieved to obtain zinc melt powder.

2. The method for recycling cemented carbide according to claim 1, characterized in that: The smelting temperature is 500°C to 900°C.

3. The method for recycling cemented carbide according to claim 1, characterized in that: The smelting time is 10h to 15h.

4. The method for recycling cemented carbide according to claim 1, characterized in that: The mixing mass ratio of the cemented carbide to the zinc is 1:1 to 1:

2.

5. The method for recycling cemented carbide according to claim 1, characterized in that: The temperature of the vacuum distillation is 950° C. to 970° C., and the time of the vacuum distillation is 10 h to 20 h.

6. The method for recycling cemented carbide according to claim 1, characterized in that: The average particle size of the zinc molten powder is less than 0.15 mm.

7. The method for recycling cemented carbide according to any one of claims 1 to 6, characterized in that: The following processes are also included: After acid leaching and solid-liquid separation of the zinc molten powder, oxidative roasting is performed in air to convert tungsten into tungsten oxide to obtain an oxidized product; The oxidation product is subjected to alkali leaching, and the tungsten oxide is dissolved by the alkali to obtain a soluble tungstate leachate.

8. The method for recycling cemented carbide according to claim 7, characterized in that: The temperature of the oxidation roasting is 500° C. to 900° C., and the time of the oxidation roasting is 1 hour to 10 hours.

9. The method for recycling cemented carbide according to claim 7, characterized in that: The alkali solution used for the alkali leaching includes one or more of NaOH, Na2CO3, and ammonia water.

10. The method for recycling cemented carbide according to claim 7, characterized in that: The temperature of the alkali leaching is 90°C to 100°C; The alkali leaching time is 2h to 6h.