Ferro Moly--Single-layer furnace roasting molybdenum concentrate

Ferro Moly--Single-layer furnace roasting molybdenum concentrate

 

Molybdenum concentrate contains about 75% MoS. Because of its high sulfur content, it cannot be used to directly smelt ferromolybdenum and produce molybdenum oxide blocks, so it must be oxidized and roasted to remove sulfur before it can be used. It is customary that the molybdenum concentrate before roasting is called raw molybdenum concentrate, and the molybdenum concentrate after roasting is called cooked molybdenum ore or molybdenum roasted sand.

 

Before adding concentrate to the roasting furnace, the ingredients should be prepared according to the molybdenum content and impurity content, and should be fully mixed. The error of the molybdenum content in the prepared ingredients should be within 0.2%, Mo≥45%, Pb≤0.8%, Cu≤ 0.6%, SiO2≤12%, CaO≤3%, H2O≤4%.

 

A reverberatory furnace with only one hearth is called an interlayer furnace. The general single-layer furnace parameters are: hearth height 850mm, hearth length 6000mm, hearth width 1500mm, hearth height 500mm, and 4 furnace doors.

 

The furnace is built with refractory clay bricks. The stove has a coal-burning combustion chamber and an ash pit below the combustion chamber. In the middle is a hearth about 850mm high, 1500mm wide and 6000mm long. The stove has a top and a barrier to prevent the concentrate from falling into the combustion chamber and horizontal flue. wall, the furnace end retaining wall is slightly higher. There are generally 4 furnace doors. It is customary to call the furnace door near the tail the first furnace door, and the furnace door near the combustion chamber called the fourth furnace door. The first furnace door is loaded with molybdenum concentrate, and the fourth furnace door is For discharging, all furnace doors can be used for stirring and stirring.

 

There is a pit with a partition wall at the end of the furnace, where large particles of molybdenum dust are collected, and then the flue gas enters the vertical flue part, and then to the horizontal part of the main flue. The main flue leads to the dust collection room. Single-layer furnaces generally have horizontal flue gases. The channel is longer to facilitate the recovery of smoke and dust, and finally the smoke enters the chimney.

 

The concentrate must pass through a 2mm sieve before being loaded into the furnace to increase the contact area between the concentrate and the gas and increase the reaction speed.

 

Load about 300kg at a time, lay it flat on the hearth in the door area of the first furnace, about 65mm thick, and roast continuously for about 120 minutes before moving forward to the door area of the second furnace. About 120 minutes later, move forward to the entrance area of the third furnace. It takes approximately 8 hours from the charging of each furnace door to the discharge of the fourth furnace door. When the first furnace door area has been moved forward, the prepared concentrate will be added to the first furnace door area for continuous roasting. 

 

The gas temperature at the door of the first furnace is 503-573K, and the concentrate temperature is 453-503K. The first furnace door area mainly removes oil and moisture, and stirs every 30 minutes or so. The gas temperature at the door of the second furnace is 673-723K, and the concentrate temperature is 683-733K. The second furnace door area is mainly used to heat the concentrate and desulfurization reaction occurs. It is stirred every 20 minutes. The gas temperature at the entrance of the third furnace is 813-853K, and the concentrate temperature is 823-873K. The entrance area of the third furnace removes about 75% of the total sulfur and is stirred every 10 minutes.

 

The gas temperature at the entrance of the fourth furnace is 873-953K, and the concentrate temperature is 883-973K. The door area of the fourth furnace is close to the combustion chamber, and the furnace gas temperature is relatively high. Here, the concentrate is burned until the sulfur content is less than 0.07% before it can be released from the furnace. It is stirred every 7-8 minutes. When solidification occurs, open the furnace door and stir continuously until the concentrate is desulfurized when dispersed. At this time, it should be discharged immediately.

 

The temperature control of each furnace door can be achieved by adjusting the heat supply of the insert plate at the rear of the furnace and the combustion chamber. Try to control the concentrate temperature below 923K to reduce volatilization. The recovery rate of molybdenum concentrate roasted in a single-layer furnace is about 94%.