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| Three points should be paid attention to when selecting Anthracite carbonizing agent |
| 2023-06-10 15:31:19 Number of visits：2172 |
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When selecting carburetors, the following points should generally be noted.
1. Fixed carbon and ash content
Carbon sequestration and ash content are two opposite parameters in carburizing agents, and they are also two important parameters that affect carburizing efficiency. If the fixed carbon content and ash content in the carburetor are high, the carburetion efficiency is high, and if not, the carburetion efficiency is low. Due to the influence of many uncertain factors under certain conditions, it is difficult to strictly evaluate the impact of each of the two parameters on the efficiency of the carburetor.
High ash content has an inhibitory effect on carbon increase and can also increase the amount of slag, thereby prolonging operation time, increasing power consumption, and increasing labor during the smelting process. Trench type induction furnace shall be adopted. If carburant is added in the furnace, low ash type shall be selected in particular to avoid oxide accumulation in the trench, which will affect Electrical efficiency. From the perspective of carbon efficiency, we can consider that of course, we hope that the fixed carbon content of the carburetor is higher and the ash content is lower. However, at the same time, enterprises also need to consider the factors of social management costs and the impact on the quality of molten iron. The addition method of carburizing agent also has a significant impact on the carburizing efficiency.
a. Carburizer is added to the furnace during loading
When loading, mix the carburizing agent with the furnace material and place it in the bottom and middle of an induction controlled electric furnace, which has a high carburizing efficiency. With regard to the carburizing efficiency of different carburizing agents, some people have carried out comparative tests under the condition of keeping Ceteris paribus unchanged. The main points are summarized as follows: when gray cast iron is smelted in a coreless induction furnace, the target carbon equivalent of cast iron is 0.3% (C3.4%, Si1.9%, Mn0.55%). The burden ratio is: cast pig iron 16%, recycled material 30%, scrap steel 52%, and carburizing agent 2%.
b. Adding carburetor during ironing
Adding a carburetor to the ladle during casting has a much lower carburetion efficiency than adding it to the furnace. Someone has conducted comparative experiments by adding different carburetors to the bag, and the key points are as follows: the melted cast iron is low-carbon equivalent cast iron, with a target composition of C 2.55%; Si 1.7%; Mn 0.4%. When casting iron, the temperature of the molten iron is between 1510 and 1530 ℃.
2. Sulfur content
When melting ductile iron, low-carbon carburetors with low sulfur content should be used. Although the price of low-carbon carburetors is high, they are necessary for us.
When melting gray cast iron, it is advisable to use carburetors with higher sulfur content. In this way, not only can costs be reduced, but the sulfur contained in it can also be utilized to enhance the responsiveness of molten iron to inoculation treatment, resulting in high-quality metallurgical castings. Under such economic conditions, one-sided pursuit of "high quality" carburetors and selection of low sulfur brands can not only increase enterprise management costs, but also have a negative impact on product and service quality.
3. Nitrogen content
There is a small amount of nitrogen in Gray iron, which promotes the formation of pearlite and improves the mechanical properties of cast iron. If the nitrogen content (mass fraction is above 0.01%), the casting is prone to producing "nitrogen induced porosity" . The nitrogen content in scrap steel in an iron smelting furnace is higher than that in cast pig iron. When smelting cast iron in an induction furnace, due to the use of fewer pig iron ingots and more scrap steel in the furnace material, the nitrogen content in the cast iron will be correspondingly higher. When the amount of scrap steel in the furnace material is 15%, the nitrogen content in cast iron is about 0.003~0.005%; When the amount of scrap steel is 50%, the nitrogen content can reach 0.008-0.012%; When all the furnace materials are scrap steel, the nitrogen content may reach over 0.014%. In addition, due to the use of a large amount of scrap steel in different furnace materials, carburetors must be used, and most carburetors generally have a relatively high nitrogen content, which is another factor leading to a significant increase in nitrogen content in cast iron.
In the past decade, with the increasing usage of induction furnaces, the nitrogen content in carburetors has received increasing attention. In order to avoid porosity in castings, carburizing agents with low nitrogen content for induction furnace melting should be selected. If possible, the nitrogen content in the carburetor should be checked. The difficulty lies in the lack of a simple and accurate method for analyzing the nitrogen content of carburetors.
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