Molybdenum Concentrate Smelting Process

In order to ensure the quality of molybdenum concentrate, it is sometimes necessary to further separate the heavy metal minerals such as copper, lead, iron and calcium oxide and carbonaceous minerals contained in molybdenum concentrate, such as the use of sodium sulfide, sodium hydrosulfide, cyanide or ferrocyanide to inhibit the copper and impurity content. Molybdenum concentrate smelting mainly uses the following methods:

Oxidation roasting: molybdenite is roasted to obtain molybdenum roasting sand, then molybdenum trioxide is obtained by sublimation or wet process, and ammonium molybdate is generated into the solution when leaching with ammonia, which is separated from insoluble materials. The solution is concentrated and crystallized to get ammonium molybdate crystals, or acidified with acid to produce molybdate precipitate, thus separating from soluble impurities. Both are calcined to produce pure molybdenum trioxide, which is then reduced by hydrogen to produce molybdenum metal. Depending on the roasting equipment or the added components, the method can be divided into rotary kiln roasting process, reflector furnace roasting process, multi-chamber furnace roasting process, fluidized bed roasting process, and flash furnace roasting process. The method will produce a large amount of smoke, pollution of the environment, molybdenum recovery rate is low, accompanied by the rare element rhenium almost all run away with the smoke, is not suitable for processing low-grade ores and complex ores.

Nitric acid leaching method: in the autoclave to make MOS2 oxidized to soluble molybdate, the method is mainly consumed cheap oxidant - air or pure oxygen. This method requires high temperature and high pressure, high requirements for reaction equipment, reliable reaction conditions, great technical difficulties in production, and the process conditions of the leaching process are also more difficult to control, and there are certain safety hazards in the production process, and the use of this method has been suspended in China at present.

Sodium hypochlorite leaching method: It is mainly used to deal with the leaching of low-taste medium ore and tailings. In the process of oxidative leaching, sodium hypochlorite itself will slowly decompose and precipitate oxygen, and some other metal sulfides will also be oxidized by sodium hypochlorite, and the ionic cargo hydroxide of these metals will be produced with molybdate to produce molybdate precipitation, which promotes molybdenum of the solution to return to the slag. The method of reaction conditions are mild, the production is easy to control, the equipment requirements are not high, but the raw material sodium hypochlorite consumption is large and cause the production cost is too high.

Electro-oxidation leaching method: It is improved from sodium hypochlorite method, which is to add the molybdenite material that has been slurried into the electrolytic tank equipped with sodium chloride solution, in the process of electro-oxidation, the anode product Cl2 reacts with water to produce hypochlorite, which then oxidizes molybdenum sulfide in the minerals, so that molybdenum enters into the solution with molybdenum in the form of molybdenum in the form of molybdenum acid radicals. This method inherits the characteristics of high leaching rate of sodium hypochlorite, mild reaction conditions, no pollution, and can be more convenient to control and adjust the direction, limit and rate of the reaction.

At present, there are also some new methods, such as molybdenum pyroxene concentrate without oxidizing roasting, directly using oxygen pressure cooking method or bacterial leaching method to extract pure molybdenum trioxide. For low-grade oxidized ore leaching with sulfuric acid, from the solution with ion exchange method or extraction method to extract pure molybdenum trioxide.