How Is Molybdenum Mined and Processed?

Molybdenum is a very important non-ferrous metal. It has extremely high hardness, corrosion resistance, and the third-highest melting point (2,623°C) of all metals. Thus, it is one of the most valuable alloying agents in various steels and cast irons.

1. Molybdenum mining

Molybdenum exists in many minerals, but only molybdenite is suitable for the industrial production of molybdenum products.

Molybdenite can be the only mineralization in a single ore body, but it often co-exists with other metals, especially copper. The molybdenum (Mo) content of various ore bodies is between 0.01-0.25%.

If molybdenum ore is close to the surface, open-pit mining technology is used to dig the overburden to expose the ore body for easy mining.

If molybdenum ore is located deep underground, the underground ore block caving technique is used. Large ore blocks are cut from the bottom and collapse under their weight. The resulting ore is moved to the ground for the processing.

2. Extraction of Molybdenum

The molybdenum production process is Crushing - Grinding - Molybdenum flotation - Roasting.

In the extraction of molybdenum, we adopt the segmented grinding and multi-stage separation process. No excessive grinding.

2.1 Stage I Crushing and screening

Three-stage closed-circuit crushing is in line with the principle of "more breaking and less grinding".

1. 1. Large molybdenum ore is fed into a jaw crusher by a vibrating feeder for coarse crushing;
2. 2. After coarse crushing, it is screened by a vibrating screen, and then sent to a cone crusher for medium crushing;
3. 3. Then it is sent to the sand making machine for fine crushing. The final crushing particle size of the product is 12-15 mm.

2.2 Stage II Grinding

The two-stage and one-closed grinding make molybdenum ore grind more fully.

1. 1. The crushed ore is sent to a ball mill for grinding. The molybdenum powder has a diameter of only a few microns.
2. 2. Then it is screened by a spiral classifier. The qualified molybdenum powders are sent to the floatation machine, while the rest continues to be ground.

2.3 Stage III Molybdenum flotation

The extraction of molybdenum adopts preferential flotation.

The molybdenum powder and gangue powder are mixed with floatation agents and aerated. Then molybdenum concentrate is obtained in the flotation machine, containing 85%-92% molybdenum disulfide.

How are the floatation reagents used?

• Collectors: Non-polar oils?such as Syntex (activated carbon), Xanthate Ester.
• Regulators: Lime.
• Inhibitors: Water glass?cyanide or sulfide.

Inhibitors depend on the impurities contained in the molybdenum concentrate.

• Copper and iron: Use sodium sulfide or sodium hydrosulfide, cyanide, or ferricyanide.
• Lead: Use dichromate, Nokes.
• Calcium oxide: As it is easy to mud, use water glass, sodium hexametaphosphate, or organic glue as inhibitors, and finally leach with hydrochloric acid.
• Carbon minerals: Use sodium hexametaphosphate and CMC. Or use ferric chloride, water glass, and sodium hexametaphosphate.
• Silica (Sio2): Use CMC to make the Sio2 content be reduced below the standard.

If inhibitors cannot make the impurity content reach the standard, chemical beneficiation (acid leaching) can be used.

• Secondary copper sulfide is leached with cyanide.
• Chalcopyrite is leached with ferric chloride solution.
• Galena is leached with hydrochloric acid and ferric chloride solution.

2.4 Stage IV Roasting

Molybdenum concentrate is roasted in a rotary kiln at a temperature of 500-650?. Roasting converts it into Molybdenum Calcine (MoO3), also called Industrial Molybdenum Oxide (MoOx).

Molybdenum oxide contains 57% molybdenum and less than 0.1% sulfur.

In addition, molybdenum concentration contains a small amount of (0.1%) rhenium, which can be recovered by roasting, This is one of the main industrial sources of this rare metal.

Jordan is the writer of the blog with a broad knowledge of this industry. He hopes to help you in your projects sincerely. Here is the website: https://www.ftmmachinery.com/