A method for one-step comprehensive recovery of NdFeB waste flash roasting

Abstract

The invention discloses a method for performing one-step comprehensive recovery on neodymium iron boron scrap by flash roasting. After being mixed with a hydrotropic agent, the neodymium iron boron scrap is injected into the space of a high-temperature vertical reaction tower by a nozzle together with mixed gas; a material falls from the upper end to the lower end of the reaction tower in a highly-dispersed floating state; by controlling an oxidizing atmosphere in the reaction tower, rare earth in the material is rapidly and fully oxidized and enters furnace slag in a form of rare earth oxide,while iron cinders may possibly not be oxidized, and when passing through a hot coke layer arranged over a settling tank, a little oxidized iron is reduced to metallic iron; and after standing for layering, molten iron and rare earth slag are discharged from an iron outlet and a slag discharge port correspondingly, and smoke is discharged from a flue. According to the method disclosed by the invention, through oxygen-controlled flash roasting and by arranging the high-temperature coke layer, the rare earth and the iron in the neodymium iron boron scrap are effectively enriched and separated;the defects that the flow is long, energy consumption is high, the rare earth and the iron are oxidized at the same time, the amount of acid-leaching slag is large, the recovery rate of the rare earthis low, an iron resource is hard to utilize, and the like by employing a traditional disposal method for the neodymium iron boron scrap are overcome; and the method has good economic benefits and environmental protection benefits.

Description

technical field [0001] The invention relates to a one-step comprehensive recovery method for NdFeB waste flash roasting, which belongs to the technical field of rare earth metallurgy. Background technique [0002] NdFeB is a magnetic material. As the latest achievement in the development of rare earth permanent magnet materials, it is known as the "Magnetic King" because of its excellent magnetic properties and is widely used in various fields. In the production process of NdFeB magnetic materials, about 20-25% of waste will be generated, most of which are NdFeB sludge waste. These scraps contain about 60% iron and about 30% rare earth elements. The recycling of NdFeB waste not only rationally utilizes resources, but also reduces environmental pollution. [0003] At present, NdFeB oil sludge waste is often roasted in a two-stage rotary kiln, and then leached-extracted-precipitated-burned to recover the rare earths. The first stage of rotary kiln roasting is mainly to remo...

AI Technical Summary

Problems solved by technology

The first stage of rotary kiln roasting is mainly to remove the oil in the NdFeB sludge and provide raw materials for the second stage of deep oxidation. However, due to the inherent defects of the rotary kiln, the temperature and atmosphere cannot be precisely controlled, and the deoiling process is often insufficiently burned, resulting in High energy consumption, and often black smoke, polluting the environment

The second stage of rotary kiln roasting often oxidizes rare earth and iron into RE as much as possible. 2 o 3 and Fe 2 o 3 , due to the slow oxidation reaction rate of the rotary kiln, it often takes 4-8 hours to achieve a high oxidation rate, and, due to the use of two-stage rotary kiln, the volume is large, the area is large, the external heat dissipation area is large, and there is heat-cold alternation link, high energy consumption

In addition, since the rare earth and iron are leached with hydrochloric acid after the simultaneous oxidation of rare earth and iron, a large amount of iron in the waste enters the acid leaching slag, the amount of slag is large, and the total amount of rare earth taken away by the slag is large, resulting in a decrease in the total recovery rate of rare earth, while the leaching slag It is difficult to get a good comprehensive utilization by itself, and it is often stockpiled, causing environmental pollution

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