Multi-layer furnace roasting molybdenum concentrate

 

Multi-layer furnaces are commonly used at home and abroad and are a better roasting equipment. The furnace is composed of a cylindrical iron shell lined with refractory clay bricks. The center of the furnace is equipped with a central axis driven by an electric motor through a reducer. The rake arm with fixed rake teeth is fixed on the central axis, and the rake teeth are placed on the hearth. Make a circular motion around the central axis. The rake arms are cooled by air fed from the central shaft.

 

The outer diameter of the eight-layer furnace is 6034mm, the inner diameter is 5034mm, the total height is 12970mm, and the center speed is 0.75 and 0.98r/min.

 

 

During stirring, the charge moves from the outer edge of the hearth to the center of the furnace, and finally falls from the drop hole near the central axis of the furnace to the inner edge area of the second-layer hearth of the furnace. Due to the stirring and pulling of the rake, the charge moves to the outer edge of the hearth, and falls to the outer edge area of the third-layer hearth through the blanking hole. In this way, the concentrate passes through all the hearths, and the roasted mature molybdenum concentrate passes through the eighth layer. The tiered hearth falls into the storage tank below.

 

The heat released when molybdenum sulfide is oxidized is relatively large, so the fuel consumption is not large. The gas used in the roasting furnace is introduced into the sixth, seventh and eighth floors of the furnace through underground pipes and nozzles arranged around the furnace. There are air outlet pipes on floors 1-7, and the waste gas is discharged through the main pipe. Each floor is equipped with a furnace door for observing furnace conditions and adjusting temperature.

 

 

The above temperatures are allowed to be slightly different, but if the furnace temperature is too low, the roasting speed will be slowed down and low-sulfur baked sand cannot be obtained; if the furnace temperature is too high, the loss of molybdenum will increase due to the volatilization of molybdenum trioxide, and the furnace charge will Sintering into lumps and impenetrable roasting will cause the growth of the sintered concentrate layer on the hearth and accelerate the wear of the rake teeth. Therefore, special attention should be paid to the temperature control of each layer when roasting molybdenum concentrate.

 

The temperature of each layer can be adjusted by increasing or decreasing the amount of gas fed into the furnace, increasing or decreasing the extraction knife, opening and closing the furnace doors of each layer and the exhaust gas pipe valves of each layer. To increase the temperature on floors 3-7, you need to open the small furnace door on the eighth floor and increase the gas supply or close the waste gas valves on the center and seventh floors; to increase the temperature on the sixth and seventh floors, you need to increase gas consumption .

 

If the above method does not achieve the expected results, the knife must be reduced to increase the temperature of each layer. To lower the temperature, the knife must be increased. In order to reduce the excessive temperature on the 2nd to 5th floors, return products should be added, and the small furnace doors on the 3rd and 4th floors can be opened if necessary.

 

The 1-2 floors in the furnace are the preheating area, the 3-5 floors are the main desulfurization areas, and the 6-8 floors are the areas for removing residual sulfur. Controlling the solidified layer to the sixth layer is conducive to oxidative desulfurization. Therefore, when the solidified layer is moved to the fifth or seventh layer, the suction should be adjusted by reducing or increasing the suction.

 

As roasting progresses, the appearance characteristics of the concentrate also change. The roasted simmered molybdenum ore turns yellow and shiny when heated. When molybdenite is roasted in a multi-layer furnace, about 10%-15% of the dust escapes. The dust collection system generally consists of a cyclone dust collector and an electrostatic precipitator. The dust removal efficiency is 99%. The collected dust must be returned to the furnace for roasting. . Each eight-layer furnace has a day and night output of about 14 tons.