The main component of China Powder Network is calcium carbide, which is an inorganic compound, white crystal, industrial products are gray-black blocks, and the section is purple or gray. Industrially, an electric furnace smelting method is generally used, and coke and calcium oxide (molecular formula CaO) are smelted in an electric furnace at about 2200 ° C to produce calcium carbide (molecular formula CaC2). Its main industrial raw material is lime, and the quality of lime directly affects the quality of calcium carbide.
So how does the quality of lime affect the quality of calcium carbide?
1. Calcium chloride index requirements
The lime oxide content of lime will affect the quality of the lime. In the production process, in order to ensure the quality of the product, measures to accelerate the reaction speed in the calcium carbide furnace are usually used to reduce side reactions. Therefore, lime with a higher calcium oxide content should be used.
Due to the influence of production conditions and raw materials, the calcium oxide content in lime cannot meet the requirements. Therefore, product quality should be ensured by improving production technology, production conditions and rational use of limestone resources.
2. Harmful substances in lime
Silica, magnesia, iron oxide, aluminum oxide and other substances in the lime will affect the calcium carbide production activities. When the calcium carbide furnace reacts to form calcium carbide, some of these impurities also react.
The reaction of these impurities not only wastes resources, but also affects the quality of calcium carbide and even affects the safety of production activities. Therefore, impurities in limestone should be strictly controlled. Magnesium oxide is reduced to magnesium metal during the reaction and forms a high temperature reduction zone. When the magnesium vapor overflows, a part of magnesium will form magnesium oxide with carbon monoxide. The high temperature appearing during the reaction will destroy a part of the calcium carbide furnace, and the liquid calcium carbide will cause erosion when it contacts the refractory brick; a part of magnesium is in contact with When oxygen reacts, a large amount of heat is released, causing the material in the calcium carbide furnace to form a large block, and the furnace gas cannot be discharged.
In a calcium carbide furnace, the silica will be reduced to ferrosilicon, which will destroy the furnace wall and will destroy equipment such as the nozzle and the electric stone pot during the furnace. Alumina is not completely reduced to aluminum, some of which will be incorporated into the calcium carbide, which will adversely affect the quality of the calcium carbide, and most of it will be deposited on the bottom of the furnace, causing the furnace bottom temperature to be too high, affecting the normal operation of the calcium carbide furnace. Iron oxide will form ferrosilicon with silicon during the reaction, which is likely to enter the gap between the bottom of the furnace and the furnace wall, thereby reducing the life of the calcium carbide furnace. In short, according to the production requirements, the harmful substances in the lime should be restricted to ensure the safety of production activities.
3. The birth of lime
The main component of limestone is calcium carbonate. At 815 °C, calcium carbonate will decompose carbon dioxide. As the temperature increases, the decomposition rate will continue to increase. If the surface temperature and internal temperature of limestone are 815 ° C, limestone. Will decompose into lime.
If the temperature inside the limestone is lower than 815 ° C, it will not be fully decomposed. Usually, the lime containing undecomposed limestone is called raw lime. Raw calcined lime is used in the production of calcium carbide, and it needs to be decomposed to form calcium carbide. The decomposition process increases the energy consumption of the production process. In short, the production of raw lime should be controlled reasonably during the production process.
4. Lime size
Lime particle size has an important impact on the production of calcium carbide. If the particle size is large, the contact area is small, and the reaction speed will decrease; if the particle size is small, the hard layer will appear at the electrode layer, which will reduce the speed of the charge and affect the production activities. Through research, we can find that the particle size of lime is too small to be easily broken during transportation and handling, resulting in more powder during use. Therefore, the particle size of the self-produced lime should be controlled at 5 to 40 mm, and the purchased lime particle size should be controlled at 8 to 60 mm. In addition, the lime stock should be scientifically controlled to avoid the problem of chalking of lime.
Partly derived from the analysis of the influence of limestone and lime quality on calcium carbide production_Cai Zhong
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