Safe smelting and recycling method for magnesium alloy powder scraps and fragments

Abstract

The invention belongs to the field of metal smelting, and relates to a safe smelting and recycling method for magnesium alloy powder scraps and fragments. According to the method, the risk of deflagration in the smelting process is prevented by controlling the temperature to be lower than the melting point temperature of the magnesium alloy, only a small amount of refining flux needs to be added in the liquid-solid state, heating and stirring are needed to enable powder scraps to be evenly heated, and safe and efficient smelting and recycling work of the magnesium alloy powder scraps and fragments is achieved. In the smelting treatment process, the dosage of the flux is reduced by 80%, the smelting time is reduced by 30%, and the yield is doubled.

Description

Technical Field

[0001] The invention belongs to the field of metal smelting and relates to a method for safely smelting and recovering magnesium alloy powder and scraps. Background Art

[0002] Magnesium alloy has become one of the most promising metal structural materials due to its light weight, high specific strength, good heat dissipation and damping properties, and environmental friendliness. Its application in aerospace and rail transit product components is increasing. New energy vehicles also use a large amount of magnesium alloys due to their weight reduction needs. Magnesium alloy has a small hot melt, a low melting point (650°C), and requires less energy for secondary melting. It does not produce hazardous materials and has the original metallographic structure inheritance. The secondary recycled material has better performance and can be 100% recycled and reused.

[0003] The processing and manufacturing of magnesium alloys will produce a large amount of powder and debris. However, a large amount of accumulation of these powder and debris is easy to oxidize and explode. During the recycling and smelting process, the powder and debris have a low ignition point and are very easy to burn and oxidize, which not only reduces the yield but also has a greater risk of explosion.

[0004] To solve the above problems, the existing technology uses a large amount of covering flux mixed with magnesium powder to heat and melt, but it is not easy to melt at low temperature, and it will burn and oxidize at a slightly higher temperature, with low yield (30-40%) and high risk. In addition, the use of a large amount of flux (the ratio of powder to flux is 1:1) is not friendly to the environment. Even if a large amount of flux slag is smelted, it can only be used in low-end manufacturing. Another method is to melt in a vacuum state. This process method is costly and inefficient, not suitable for industrial production, and out of practice. Summary of the invention

[0005] In view of the above-mentioned shortcomings, the present invention provides a safe smelting and recovery method for magnesium alloy powder and scraps which has high finished product yield, high safety and can reduce the amount of flux used.

[0006] In order to achieve the above object, the present invention provides the following technical solutions: A method for safely smelting and recovering magnesium alloy powder and debris, characterized in that it comprises the following steps: S1: Add molten magnesium alloy material into the crucible until the stirrer blades are completely submerged; S2: Start the stirrer and slowly stir at a speed of 10-20 rpm, adding a small amount of magnesium alloy powder and fragments and refining flux during stirring; S3: Continuously heat the crucible and use a temperature measuring thermocouple to monitor the temperature in real time, so that the inside of the crucible is maintained at 490-520°C and magnesium alloy powder and fragments are continuously added until 1 / 3 of the internal space of the crucible is occupied, then the stirring speed of the stirrer is increased to 30 rpm, magnesium alloy powder and fragments are continuously added and the internal state of the crucible is monitored in real time; S4: When it is detected that there is accumulation of powder in the crucible, the feeding is stopped, and the temperature is appropriately raised until the powder melts, so that the inside of the crucible is kept in a state of a flowable paste without the appearance of liquid magnesium alloy with good fluidity and the accumulation of unmelted powder; S5: The operation of S4 is continuously repeated until the liquid level of the paste is more than 20 mm from the crucible mouth, and the smelting step is completed.

[0007] The beneficial effects of the present invention are: By controlling the temperature below the melting point of the magnesium alloy, the risk of explosion during the smelting process is prevented. In the liquid-solid phase, only a small amount of refining flux needs to be added, and the powder is heated and stirred to allow the powder to be heated evenly, thus reducing the smelting time, greatly improving the yield rate, and achieving safe and efficient smelting and recovery of magnesium alloy powder and fragments.

[0008] The above description is only an overview of the technical solution of the present invention. In order to more clearly understand the technical means of the present invention and implement it according to the contents of the specification, the following is a detailed description of the preferred embodiments of the present invention in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 The present invention is a schematic flow chart of a method for safely smelting and recovering magnesium alloy powder and scraps according to an embodiment of the present invention. DETAILED DESCRIPTION

[0010] The technical solution of the present invention will be described clearly and completely below in conjunction with the accompanying drawings. 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.

[0011] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0012] In addition, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0013] See also Figure 1 The safe smelting and recovery method of magnesium alloy powder and debris shown in a preferred embodiment of the present application comprises the following steps: S1: Add 200 kg of molten magnesium alloy material into a 1 t crucible until the stirrer blades are completely submerged.

[0014] S2: Start the stirrer and slowly stir at a speed of 10-20 rpm. During the stirring, a small amount of magnesium alloy powder and fragments and a refining flux are added; the refining flux includes potassium chloride, magnesium chloride, sodium chloride, and calcium fluoride.

[0015] S3: Continuously heat the crucible and use a temperature measuring thermocouple to monitor the temperature in real time, so that the inside of the crucible is maintained at 490-520°C and magnesium alloy powder and fragments are continuously added until 1 / 3 of the internal space of the crucible is occupied, then increase the stirring speed of the stirrer to 30 rpm, continue to add magnesium alloy powder and fragments and monitor the internal state of the crucible in real time.

[0016] S4: When powder accumulation is detected in the crucible, stop adding material and increase the temperature appropriately until the powder melts, so that the inside of the crucible is kept in a state of flowable paste without the appearance of liquid magnesium alloy with good fluidity and the accumulation of unmelted powder.

[0017] S5: The operation of S4 is continuously repeated until the liquid level of the paste is more than 20 mm from the crucible opening, and the smelting step is now completed.

[0018] The finished product is finally obtained through subsequent processes such as heating and refining the ingot. The following table shows the test results of different smelting methods, among which methods 1 and 2 are prior arts, and methods 3 and 4 are the smelting methods shown in this application.

[0019] Serial number Magnesium alloy powder Flux dosage Melting time Finished product 1 620kg 550kg 6 hours 240kg 2 701kg 680kg 6.5 hours 270kg 3 860kg 200kg 4 hours 612kg 4 815kg 180kg 4 hours 586kg It can be seen from the table that the safe smelting and recovery method of magnesium alloy powder and scraps shown in the present application reduces the flux usage by 80%, reduces the smelting time by 30%, and doubles the yield during the processing.

[0020] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0021] The above-mentioned embodiments only express several implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for ordinary technicians in this field, 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 safe smelting and recovery method for magnesium alloy powder and debris, characterized in that: The following steps are involved: S1: adding molten magnesium alloy material into the crucible until the magnesium alloy material completely submerges the blades of the stirrer; S2: starting the stirrer to stir the magnesium alloy material at a speed of 10-20 rpm, and adding magnesium alloy powder and fragments and refining flux during stirring; S3: Continuously heat the crucible and use a temperature measuring thermocouple to monitor the internal temperature of the crucible in real time, so that the internal temperature of the crucible is maintained at 490-520° C. and magnesium alloy powder and fragments are continuously added until the mixed melt occupies 1 / 3 of the internal space of the crucible, and then the stirring speed of the stirrer is increased to 30 rpm, and magnesium alloy powder and fragments are continuously added and the internal state of the crucible is monitored in real time; S4: When it is detected that there is accumulation of powder in the crucible, the feeding is stopped, and the temperature is raised until the powder is melted, so that the inside of the crucible is kept in a state of a flowable paste without the appearance of liquid magnesium alloy with good fluidity and the accumulation of unmelted powder; S5: The operation of S4 is continuously repeated until the liquid level of the paste rises to a position more than 20 mm from the crucible opening, and the smelting step is completed.

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