Five Points to Improve the Recovery Rate of Molybdenum in Production

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Molybdenum is precious rare metals. Molybdenum minerals account for 97.5% of the total cost in the production of ferromolybdenum. So, maximally improve the recovery rate of molybdenum is of great importance to reduce the cost and improve the economic benefit. It is necessary to strictly control the links that may cause the loss of molybdenum.

a. With high vapor pressure, MoO3(S) is easy to sublimate. Therefore, reduce the sublimation of MoO3(S) and recycle the molybdenum-containing dust is the significant links that should be noted.

b. In the calcination of molybdenum concentrate, the temperature should be concisely controlled. The sublimation volume of MoO3(S) should be reduced to the greatest extent, and high efficiency purification system should be equipped to calcinate the recycled molybdenum dust again.

c. During the smelting, seal the furnace body not only reduces the heat loss and the use level of aluminum reducing agent, but also reduces the loss of molybdenum in the residues and contributes to the purification and dedusting of exhaust gas. After the agglomeration of the molybdenum-containing dust collected by dust remover, returning smelting is available. The dust comprehensive utilization should be taken into consideration should the dust contains other metallic elements.

d. The ferromolybdenum particles mingled with its residues should be recycled. Magnetic separation method can be used to recycle the crushed furnace residues.

e. Finishing crumbs and nodule iron on furnace bottom are the molybdenum-containing returns largest in number. Slaked molybdenum minerals should be added into to smelt again.

The Characteristics of Molybdenum

Molybdenum is a silver refractory metal with the melting point of 2615°C. The density is 10.2g/cm3 with low expansion coefficient, almost the same with that of the electronic valve’s special type glass.

Molybdenum is stable under normal temperature, and will rapidly oxidate when above 600°C. It has corrosion resistance against dilute sulphuric acid, hydrofluoric acid, phosphoric acid, etc. but can not resist the corrosion of nitric acid, aqua regia, and oxidability fused salt. Molybdenum can not react with hydrogen, but molybdenum powder can absorb hydrogen. It can react with carbon, hydrocarbon, or carbon monoxide to produce molybdenum carbide under temperature of over 800°C. The molybdenum minerals that are of industrial value are molybdenite in the majority. The secondary ores of molybdenum such as powellite, ferrimolybdite, achrematite, lindgrenite, etc. also have some exploitation value. Molybdenum is of wide uses: adding it into the steel and iron can enhance intensity, tenacity, and corrosion resistance, making it one of the best alloy adding elements. Its use of level occupies 85% of molybdenum’s total usage. The nickel-based alloy adds more molybdenum than other alloys: adding 15% to 30% of molybdenum can greatly improve the corrosion resistance performance; the nickel-based alloy containing 18% molybdenum and 18% chrome can withstand the high temperature of 1093°C; Mo-Re alloy seamless tube that consists of 50% molybdenum and 50% rhenium has good high temperature properties, which can be used even when close to its melting point.

Molybdenum has wide application in electronic industry (For example, silicon wafer bearing and light source electrode outgoing line). It can also be used in the aviation and aerospace industry as high temperature resistance components. Compounds of Mo can be used as catalyst and reagent. It can also configure the pigment. Molybdenum disulfide solid lubricant is renowned as “the king of lubrication”. Molybdenum is also one of the terrific microelement chemical fertilizers in agriculture. China has abundant molybdenum resources, with its reserves in the world front rank. Molybdenum mineral has wide distribution all over China: Jinxi City of Liaoning, Jin Duicheng of Shaanxi, Jilin, Shanxi, Henan, Fujian, Guangdong, Hunan, Szechwan, and other provinces all have molybdenum minerals. Among which Jin Duicheng molybdenum mineral is the most famous, not only with huge reserves, but also good exploitation conditions. Its molybdenum mineral output occupies an important position in China. Due to this reason, it is praised as “The Capital of Molybdenum”. Molybdenum industry develops very fast in recent years, China’s ferromolybdenum, ammonium paramolybdate, and molybdenum powder plays an important role in the international market.