Molybdenum News Center

At present, most domestic SMEs are using kiln firing process. Compared with the multiple hearth furnaces, rotary kilns small investment, simple equipment and technology. The main problem kiln firing process is the production capacity of small, short furnace life, low productivity, high calcine containing MoO2 affect the rate of subsequent ammonia leaching process to extract molybdenum, and therefore rarely use this technology abroad. 

 

Reverberatory furnace is an ancient craft methods, now part of the domestic small businesses still use reflection furnace production MoO3. Molybdenite roasting when feeding, the materials are manual stirring charge, firing heavy oil or gas heat generated by burning coal supply, combined with door control calcination temperature. 

 

Foreign companies to use more multiple hearth furnace roasting process, climax company earlier multi-hearth furnace processing molybdenite roasting process, China is currently the largest multi-hearth furnace for the Jinduicheng Molybdenum Company's 12-storey four rake arms multiple hearth furnaces. Disadvantages of a multiple hearth furnace capacity is limited, much of the movable member, the short life of the furnace, temperature. 

 

Fluidized roasting of molybdenum is considered as the ideal way of roasting. Fluidized bed roasting is a more advanced firing technique has the advantage of a high oxidative desulfurization, widely used in smelting of sulphide ore production. 1998 embankment chemical company designed and produced by the vibration feeder, air distribution system, the flow of gas preheating device and expander like fluid bed roaster. The furnace has been replaced by the use of a multiple hearth furnace 60 years, and achieved good results, molybdenum conversion rate of 99%. 

 

Many scholars have conducted experimental study flash furnace roasting molybdenite, and achieved satisfactory results, but no reports of industrialization. Using flash processing molybdenum concentrate roasting method is the use of flash furnace roasting production MoO3. Molybdenum concentrate preheated (650 ~ 750 ℃) after adding the flash from the top of the furnace, preheated in contact with oxygen-enriched air or oxygen and sulfur dioxide mixed gas reflux. Furnace roasting process by adjusting the reaction zone of the cooling water temperature of 550 ~ 650 ℃, in order to control the rate of oxidation of molybdenite, ensure that the material most sublimation of rhenium and molybdenum as possible to prevent evaporation, and through smoke rhenium recovery. Molybdenum, rhenium recoveries were high, in which rhenium is about 95% recovery. Since the roasting process more fully utilize the oxygen, of sulfur dioxide in the flue gas may be liquefied to produce a liquid sulfur dioxide, sulfur-containing flue gas to avoid environmental pollution. 

 

Roasting process research focused on ways to improve the roaster or roasting, use of molybdenum sulfide roasting Process get MoO3, there are many problems in the process:
(1)Produce large amounts of smoke, serious environmental pollution  about molybdenum concentrate roasting process. Flue gas containing a large number of SO2, and low concentrations of difficult recovery. In addition, it also contains a lot of metal dust. 

⑵ in the roasting process, so that about 3% of molybdenum in the form of dust from the flue gas losses in subsequent ammonia leaching process there are more than 5% of the molybdenum in the form of slag lost, the entire production process molybdenum recovery of only 85 % ~ 90%, Hui rare element rhenium molybdenum concentrates in almost all associated with the flue gas to run away, only a handful of domestic manufacturers for recycling and recovery of rhenium is only about 70%. 

⑶ traditional process is not suitable for processing low-grade ore and mineral complex with the development of the molybdenum industry, molybdenum ore will be fewer and fewer high-grade and easy to handle, while the proportion of low-grade and complex ore will gradually increase. 

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