Recarburizer manufacturers teach you tips on the use of recarburizers
As a manufacturer of recarburizers, we often encounter customer questions about how to use recarburizers. How much should I add? When is it added? This series of problems need to be taken seriously. In the long-term practice process, Anyang Huatuo Metallurgical Technical Engineer summed up some tips on the use of recarburizers, and the correct use of recarburizers, the effect you unexpected.
First, the effect of the addition of carbonizing agent on the absorption rate of the recarburizer:
A furnace internal input method:
The recarburizer is suitable for melting in an induction furnace, but it is not the same depending on the process requirements.
(1)) The use of a recarburizer in the smelting of the intermediate frequency electric furnace can be added to the lower part of the electric furnace according to the ratio of the ratio or the carbon equivalent, and the recovery rate can reach more than 95%;
(2)) If the amount of carbon is insufficient to adjust the carbon content, firstly clean the slag in the furnace, add the recarburizer, heat the iron solution, electromagnetic stirring or artificial agitation to dissolve and absorb the carbon, and the recovery rate can be about 90%. If a low-temperature carbonization process is used, that is, when the charge is only melted and the molten iron temperature is low, all the recarburizer is added to the molten iron at one time, and the solid charge is pressed into the molten iron to prevent it from being exposed. The surface of the iron. This method can increase the carbon content by more than 1.0%.
B furnace outside the carbon:
(1) Spray graphite powder in the bag
The graphite powder is used as a recarburizer, and the blowing amount is 40kg/t, which is expected to increase the carbon content of the molten iron from 2% to 3%. As the carbon content of the molten iron gradually increases, the utilization rate of carbon decreases, the temperature of the molten iron before the carbon addition is 1600 ° C, and the average after the carbon increase is 1299 ° C. Spray graphite powder to increase carbon, generally using nitrogen as carrier, but under industrial production conditions, it is more convenient to use compressed air, and the combustion of oxygen in compressed air produces CO. The chemical reaction heat can compensate part of the temperature drop, and the reducing atmosphere of CO is beneficial to Improve carbonization.
The 100-300 mesh graphite powder recarburizer can be placed in the bag or flushed with the flow from the iron tapping tank. After the molten iron is discharged, the carbon is dissolved and absorbed as much as possible, and the carbon recovery rate is about 50%.
Second, the time of adding carbonizer
If the addition time of the recarburizing agent is too early, it is easy to adhere to the vicinity of the bottom of the furnace, and the recarburizing agent adhering to the furnace wall is not easily melted into the molten iron. On the contrary, if the joining time is too late, the timing of carbon increase will be lost, resulting in slow smelting and heating time. This not only delays the time of chemical composition analysis and adjustment, but also may cause harm due to excessive temperature rise. Therefore, the recarburizing agent is preferably added little by little during the process of adding the metal charge.
For example, if the amount of addition is too large, it can be combined with the iron superheat operation used in induction furnace to ensure that the absorption time of the recarburizer in the molten iron is 10 min, and on the other hand, the recarburizer is fully diffused by electromagnetic stirring. Absorbs to ensure absorption. On the other hand, the amount of nitrogen introduced into the recarburizer can be reduced.
Third, the electric furnace smelting method of feeding:
The recarburizer should be placed together with the charge such as scrap steel, and the small dose can be added to the surface of the molten iron. However, it is necessary to avoid feeding large quantities into the molten iron to prevent excessive oxidation and the carbonization effect is not obvious and the carbon content of the casting is insufficient. The amount of the recarburizer added is determined according to the ratio of other raw materials and the carbon content.
Fourth, the following is an improvement on some methods of adding carbonizers summarized by engineers of Henan Hengxing Metallurgical Technology Department.
Do not add it in one time, add it in batches, melt it and add a part, put a part (about one pack) of molten iron into the bag, and then return to the furnace for 1-2 times of carbonizing agent, then slag and add alloy;
Fifth, to improve the absorption rate of recarburizers need to pay attention to the following aspects:
1. Recarburizer is more difficult to absorb (not calcined)
2. The ash content of the recarburizer is large, and the particle distribution is uneven.
3. Joining time is too late
4. The method of addition is incorrect, and the layering is added. Join when avoiding too much slag on the iron mirror
5. Try not to use too much rust material.