Method for double-flash direct comprehensive recovery of neodymium iron boron waste

Abstract

The invention discloses a method for double-flash direct comprehensive recovery of neodymium iron boron waste. The method comprises the steps that the neodymium iron boron waste and oxygen-rich air are sprayed into a high-temperature vertical reaction tower together through a nozzle, materials float down from the upper end of the reaction tower to the lower end of the reaction tower in a highly dispersed floating state, and rare earth and iron in the materials are quickly and fully oxidized; oxidation products and reductive gas are sprayed into another high-temperature vertical reaction towertogether through a nozzle, iron oxide in the materials is mostly reduced into metal iron, and when passing through a hot coke layer on a settling pond, a small amount of non-reduced iron is reduced into metal iron; and after standing layering, molten iron and rare earth slag are discharged out from an iron outlet and a slag discharging outlet. According to the method, efficient enrichment and separation of the rare earth and the iron in the neodymium iron boron waste are realized, the defects that by adopting a traditional neodymium iron boron waste treatment method, the process is long, energy consumption is high, the rare earth and the iron cannot be separated before acid dissolution, the acid dissolution iron slag amount is large, the rare earth recovery rate is low, and iron resourcesare difficult to recover are overcome, and good economic and environmental protection benefits are achieved.

Description

technical field [0001] The invention relates to a method for direct and comprehensive recovery of NdFeB waste double flash, belonging 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 remov...

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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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