Study On The Process Of Producing MoO₃ By Recovery From A Low-grade Molybdenite

Molybdenum trioxide is widely used in chemicals, catalysts, pigments, steel, ceramics, glass, and the production of molybdenum precision alloy. Low-grade molybdenite tailings occurs in the process of molybdenum ore flotation.It is a behavior of wasting molybdenum resources that not dealing with the large amount of tailings.Tailings impropriates the limited land resources.The surface water and the groundwater,even the environment around us would be polluted by the tailings.It has a great meaning if we can recover molybdenum from the low-grade molybdenite tailings.And it can also help to increasing the molybdenum supply.This thesis has done a process study and pilot plant testwork of producing MoO3 by recovery from a low-grade molybdenite, and also realized the criteria optimization in the process of pilot plant testwork, solved the problems occurred during the engineering.It shows that the recovery process has good economic returns after the economic analysis had done.First,a fixed roasting and leaching conditions had been determined. And then determinated the molybdenum final content of the leach residue by the Spectrophotometry method. The best ratio of 1.0:1.0 with the raw materials and additives had been determined. On this basis, the add-form of the additives, mixing time, the roasting temperature and roasting time, raw material thickness were studied.And get the best roasting process parameters: 650℃roasting temperature and roasting time was 4 h, 8 cm thickness of raw material, 180μm particle size of additives added with solid form, the ratio of the raw materials and additives is 1.0:1.0.With the best roasting process conditions,prepares qualified molybdenite calcine. Researching the relations with the leaching L/S,leaching temperature , agitate speed and molybdenum leaching rate. Obtains the best leaching parameter.Three kinds of resin,D296R,D290,201×7,were used to study adsorption and desorption performance for molybdenite liquor.Spectrophotometry was use to determine the molybdenite liquor concentration.It shows that D296R is the best one with the adsorption capacity of 53mg/ml.A set of fixed bed,with the diameter 50mm and height 500mm,was built to study the adsorption and desorption effect. Then obtains the best ionic exchange parameter.At the last, using the HCl as molybdenum precipitation agent,study on precipitation behavior under different conditions.Baked the Ammonium molybdate product and get MoO3.Secondly, carries on the pilot plant testwork base on the low-grade molybdenum recover process which is established by lab experiment. The scale of the pilot plant is producing molybdenum trioxide 20t/a. Researching and solve the problem occurred in the engineering.and make a success on the pilot plant. The optimized technical parameter is: the ratio of the raw materials and additives is 1.0:1.0, the mixing time is 60min, the roasting temperature is 620℃, the roasting time is 2h, the leaching temperature is 60℃, leaching time is 1h. The production molybdenum trioxide product achieves the YS/T 639-2007 standards. Finally,carries on the simple economic efficiency analysis, explains the feasibility of the process.