The smelting process of magnesium alloy furnace
Because molten magnesium alloy furnaces burn when exposed to air, contact between the alloy and air must be avoided as much as possible. When the furnace temperature reaches 350℃, the protective gas mixer will automatically supply protective gas proportionally (SF6 in the mixture is 0.5 of N2). The protective gas is SF6(or SOR2R)+N2. In case of power failure, the protective gas can be continuously provided. The distribution of the protective gas in the furnace is: air, nitrogen N2, SF6(SOR2R) magnesium liquid.
Smelting equipment items include the following:
1. Preheating furnace that can preheat magnesium ingot to more than 150℃;
2. Ingot feeding furnace equipment;
3. Melting system;
4. The crucible of the furnace is medium carbon steel, wrapped with a layer of heat-resistant steel;
5. The conveying of the feeding liquid is completed by electrically heated nickel-free heat-resistant steel pipe;
6. The feeding liquid can be added to the die casting machine through the following equipment, such as manual feeding, siphon, air pump, piston pump, electromagnetic pump, etc.;
7. The furnace has a lid. It is equipped with the necessary temperature measurements, level control, feed pipe, feed pump, protective gas system, and openings for inspecting and cleaning the furnace
It is well known that when molten metal comes into contact with or mixes with water, no matter what kind of metal it is, the water immediately turns into steam, triggering what is known as a blowout explosion. Magnesium reacts not only with water, but also with heat and hydrogen. Depending on the amount of water, the reaction could also cause a hydrogen explosion, which could lead to a serious disaster. Therefore, care must be taken with dried magnesium ingot and with items that may come into contact with molten magnesium. Keep the working point dry during die casting. Therefore, magnesium ingot should not be put into molten magnesium alloy furnace before preheating to 150℃.
The preheating temperature of magnesium alloy furnace is 150℃~350℃. The boiling point of water is 100 degrees Celsius, so the low temperature is 150 degrees Celsius. With the increase of temperature, the chemical properties of magnesium alloy furnace become more and more active and prone to chemical changes (oxidation). When the magnesium alloy furnace is heated to 350℃, protective gas should be used for protection.
Magnesium alloy furnaces can melt in a furnace heated by electric wires, oil or gas. Gas heaters are widely used in the United States because of the low cost of gas. However, electric heating furnaces are now widely used because scale on gas furnaces can cause crucible wear and moisture formation. In Europe, electric furnaces dominate. Electric heater is simple to operate and can accurately control temperature. The thermocouple is installed in the furnace and near the heating element to prevent overheating.
Magnesium alloy continuous ingot casting machine manufacturers said that, at present, lead ingot casting equipment has been widely used in domestic lead smelters, the main operation has achieved varying degrees of mechanization or automation, casting, the use of lead pump molten lead pot liquid lead pump into the casting bag, liquid lead through the casting bag quantitative pouring device injected into the ingot mold for casting, scraper liquid lead ingot surface slag layer, Then, after cooling forming, printing and demudding process, the demudding lead ingot is stacked by cantilever hanging. It plays an active role in improving the working conditions and reducing the labor intensity of finished lead ingot.
The core of magnesium alloy continuous ingot casting machine is continuous casting technology. Continuous casting is a casting method in which liquid metal is continuously injected into one end of the die and molding materials are continuously pulled out from the other end. When the casting is drawn from the metal form to a certain length, the casting can be cut off while pouring; It is also possible to stop pouring when the casting reaches a certain length in order to obtain a certain length of casting. Magnesium alloy continuous ingot casting machine can be used for casting various high density plate, round bar, hollow pipe and other profiles.
Magnesium alloy smelters say that magnesium alloys are very active among all metals because they have an ignition point of 550℃ and a melting point of 650℃. At high temperatures, it reacts with oxygen to form magnesium oxide, while it reacts with water to form hydrogen and magnesium oxide, which causes an explosion. Therefore, metal oxidation or combustion must be prevented effectively in the process of melting magnesium alloy, which is usually achieved in the process of flux or no flux on the surface of metal melt. A large number of experimental studies show that gases such as C02.S02.SF6 can play a good protective role on magnesium and its alloy melt, but these substances will react with magnesium to form other substances. Such substances constitute impurities in magnesium soup, and a large number of impurities will float on the surface of the molten soup or adhere to the furnace side wall, and the dense ones will sink to the bottom of the furnace. When the substance becomes thicker and more concentrated, a large amount of this substance adheres to the crucible wall of the furnace. After a period of time, it will form a hard solid layer of material, causing a decrease in the volume of crucible. At the same time, heat from the external heating device of crucible cannot be properly transmitted into crucible, which reduces the melting speed and cannot meet the production requirements, thus reducing the production efficiency of die casting and seriously affecting the service life and product quality of crucible.
The shell of magnesium alloy furnace is made of high quality steel plate and high quality insulation material. The furnace has advanced structure, low energy consumption and fast melting speed. The design of double chamber crucible is reasonable and can be used in two die casting machines at the same time. High quality imported radiation processing thermal components, long service life, high thermal efficiency.
What are the advantages of magnesium alloy smelters? Let's find out.
In magnesium alloy smelting process, metal oxidation reaction should be avoided to prevent metal combustion. To achieve this effect, we usually sprinkle some flux on the metal melt. Sometimes, we can also use fluxless processes. The common flux is beryllium metal, and the common flux free process is flux free melting. The melting process of magnesium alloy is mainly flux melting. The flux removes impurities from the magnesium and forms a protective film on the surface of the magnesium alloy melt to isolate air. However, the effect of flux film on air isolation is not very ideal, and the magnesium loss caused by oxidation combustion in smelting process is relatively large.