System and method for acidizing and roasting rare earth concentrate through multi-section external heating rotary furnace

Abstract

The invention discloses a method and system for acidizing and roasting rare earth concentrate through a multi-section external heating rotary furnace. The method comprises the following steps of metering and putting the rare earth concentrate into an external heating rotary drying furnace, controlling heating temperature of materials and staying time in the furnace, exhausting tail gas, conveyingdust and sulfuric acid into a rotary acidifying furnace, and controlling the temperature of the materials and the staying time in the furnace; exhausting the tail gas entering an acidified tail gas recovery device after the tail end reaches the standard; enbaling acidified materials to enter a rotary roasting furnace to be roasted, controlling the temperature of the materials and the staying timein the furnace, and exhausting roasted tail gas entering a roasting tail gas recycling device after the roasted tail gas reaches the standard; and enabling high-temperature roasted materials to entera rotary cooling furnace to be cooled and be conveyed to a water leaching procedure so as to obtain the acidified roasted rare earth concentrate with the roasted material leaching rate being 93%-98%.According to the method, the tail gas treatment amount and operation cost are greatly reduced, the fluidity of the dried rare earth concentrate is good, the corrosion rate of equipment and pipelines is reduced, and equipment pipeline blockage is reduced.

Description

technical field [0001] The invention belongs to the technical field of hydrometallurgy, and relates to a system and method for acidifying and roasting rare earth concentrates in a multi-stage external heat rotary furnace. Background technique [0002] Rare earth ore is an important mineral resource in my country, among which the rare earth reserves in Baotou Baiyun Obo mining area account for more than 80% of the country's total reserves. Baotou rare earth ore is mainly a mixture of bastnaesite and monazite. Since the 1970s, my country has used the concentrated sulfuric acid method to roast and smelt mixed rare earth concentrates, which has made important contributions to the development of my country's rare earth ore industry. During this period, two optimizations and improvements have been carried out, namely, the first generation sulfuric acid method. What is widely used now is the third generation sulfuric acid method, that is, the high temperature intensified roasting ...

AI Technical Summary

Problems solved by technology

[0004] At present, the concentrated sulfuric acid high-temperature intensive roasting method has the following disadvantages: (1) The rare earth concentrate is dried, low-temperature acidified, and high-temperature roasted in a rotary kiln, and the tail gas generated is difficult to treat.

(2) The internal heating type rotary kiln is adopted, which has a large amount of gas to be processed, and the temperature of the exhaust gas is high, so it requires more energy consumption to cool down and treat the exhaust gas

(3) The generated waste gas and sulfuric acid vapor are easy to leak, resulting in poor site environment and serious pollution

Although this patent roasts and decomposes the rare earth concentrate step by step, it adopts the internal heating rotary kiln acidification roasting process, and the waste heat carried by the exhaust gas is reused, which makes the exhaust gas volume large and makes the subsequent treatment of the exhaust gas more difficult.

[0007] Although the above methods use step-by-step roasting to smelt rare earth concentrates, because of the internal heating rotary kiln acidification roasting process, the processing gas volume and dust volume are large, and it is easy to block the pipeline, resulting in high operating costs and frequent maintenance.

At the same time, due to the high moisture content in the heating flue gas, the equipment is corroded during acidification and roasting, so the labor intensity is relatively high, the on-site working environment is poor, and the production efficiency is low.

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