Femo process--methods to deal with abnormal smelting process
Abnormal phenomena, causes, consequences and treatment methods in the smelting process are:
(1) Other phenomena are normal, but there is a lot of splashing. This is caused by the moisture in the furnace charge, excessive unit calorific value, or moisture in the sand nest. This phenomenon can easily cause furnace leakage or furnace charge splashing to injure people, making the silicon content of the alloy too high. If the calorific value is high, it is necessary to reduce the aluminum particles and increase the amount of ferrosilicon powder; if the furnace charge or sand nest is moist, the drying problem of the furnace charge and sand nest must be solved.
(2) The reaction is too intense, with a lot of splashing, the reaction time is very short, and it ends quickly; after the end, the smoke is bright, the slag is sticky, and the color is blue-green. The small iron molybdenum sample taken out is easy to break after cooling, and there are bright stars on the cross section. silver white. This is a symptom of too much reducing agent, which often results in high molybdenum bottoming in silicon alloy. At this time, the amount of reducing agent must be reduced, generally by 0.3-0.7kg per batch.
(3) The reaction is smooth, the reaction is intermittent, the smoke is dark brown and rises slowly. The reaction time is long, the end is unclear and drawn out. After the furnace was pulled out, bubbles appeared on the surface of the slag surface of the ferromolybdenum ingot and there was fire. Take out a small piece of ferromolybdenum sample from the uncooled ferromolybdenum ingot and cool it, and then there will be dark brown slag hanging on the surface. The small piece of ferromolybdenum sample is very hard, the cross-section is uneven, and it is gray-black. This is a sign of insufficient reducing agent. This will lead to alloys with high molybdenum content and low silicon content (less than 0.05%), stratification of molybdenum iron ingots, easy rusting when cooling, difficulty in finishing, high molybdenum content in slag, and many metal particles. At this time, more metal particles must be added. Reducing agent generally adds 0.2-0.5kg to each batch of materials.
(4) The reaction proceeds slowly, without obvious normal smoke, and the reaction time is long. This is caused by insufficient calorific value of the charge. This often results in alloys with high molybdenum content and high silicon content. 30 minutes after the end of the iron ingot stratification or segregation reaction is the sedation and settling time of the metal particles to ensure that the molybdenum content in the slag is below 0.35%. Open the slag port, the slag flows into the slag tank, and take samples to analyze the molybdenum content. Rich slag above 0.35% is returned to smelting. Depleted residue can be discarded or comprehensively utilized. After placing the slag, pull up the furnace barrel and use an iron spoon to take the iron sample from the metal ingot on the sand base. The surface of the alloy is smooth, with micro-green slag, the fracture is dense and silver-gray, the crystals are fine, and there are no bright stars, indicating that the quality of ferromolybdenum is good. The normal alloy and slag composition ranges are as follows. , at this time, the particle size, composition and oxygen content of the charge should be checked, and then the batching ratio should be adjusted according to the specific situation.
30 minutes after the reaction is completed is the sedation and settling time of the metal particles to ensure that the molybdenum content in the slag is less than 0.35%. Open the slag port, the slag flows into the slag tank, and take samples to analyze the molybdenum content. Rich slag above 0.35% is returned to smelting. Depleted residue can be discarded or comprehensively utilized. After placing the slag, pull up the furnace barrel and use an iron spoon to take the iron sample from the metal ingot on the sand base. The surface of the alloy is smooth, with micro-green slag, the fracture surface is dense and silver-gray, the crystals are small, and there are no bright stars, indicating that the quality of ferromolybdenum is good. The normal alloy and slag composition ranges are as follows.
