METHOD FOR LEACHING OF RARE EARTH ELEMENTS IN FLUORESCENT LAMP WASTE

Abstract

A method for leaching of rare earth elements in fluorescent lamp waste is provided, which enables the direct leaching of Y and Eu in the red phosphorus within the phosphor powder and La, Ce, Gd and Tb metals, especially in the blue and green phosphorus, in a single step, without using pre-treatment step of phosphor powders in fluorescent lamp waste, which require high energy consumption.

Claims

1-10. (canceled)

11. A method for leaching of rare earth elements (REE) from fluorescent lamp wastes, comprising steps of: performing a procurement of a fluorescent lamp waste phosphorus powder, performing a size classification and a homogenisation of the fluorescent lamp waste phosphorus powder to obtain homogenised fluorescent lamp waste phosphorus powder, performing a microwave leaching process to the homogenised fluorescent lamp waste phosphorus powder in an acid solution, and performing a separation of a solid and a liquid formed as a result of the microwave leaching process.

12. The method according to claim 11, wherein the fluorescent lamp waste phosphorus powder is passed through sieves of 100 m and 45 m in size for the size classification.

13. The method according to claim 11, wherein a grinding operation for the homogenisation is carried out at a value in a range from 50 to 5000 rpm.

14. The method according to claim 13, wherein the grinding operation for the homogenisation is carried out in a ball mill at a value in a range from 0.1 to 100 h.

15. The method according to claim 11, wherein a water washing is carried out at least once after the homogenisation.

16. The method according to claim 11, wherein at least one of the group consisting of sulfuric acid, nitric acid, and hydrochloric acid is used as the acid solution in the microwave leaching process.

17. The method according to claim 16, wherein the acid solution is used at a value in a range from 0.01 to 12 M and in a volume in a range from 0.1 to 1000 L during the microwave leaching process.

18. The method according to claim 11, wherein the microwave leaching process is carried out at a temperature in a range from 15 to 250 C. for a period of time in a range from 0.1 to 20 h.

19. The method according to claim 11, wherein the microwave leaching process is carried out at a maximum of 1600 W.

20. The method according to claim 11, wherein at least one of metals Tb, La, Ce, or Gd is obtained, when blue and/or green waste phosphorus powders are used as a raw material, wherein at least one of metals Eu or Y is obtained, when red waste phosphorus powders are used as a raw material.

21. The method according to claim 12, wherein a grinding operation for the homogenisation is carried out at a value in a range from 50 to 5000 rpm.

22. The method according to claim 12, wherein a water washing is carried out at least once after the homogenisation.

23. The method according to claim 13, wherein a water washing is carried out at least once after the homogenisation.

24. The method according to claim 14, wherein a water washing is carried out at least once after the homogenisation.

25. The method according to claim 12, wherein at least one of the group consisting of sulfuric acid, nitric acid, and hydrochloric acid is used as the acid solution in the microwave leaching process.

26. The method according to claim 13, wherein at least one of the group consisting of sulfuric acid, nitric acid, and hydrochloric acid is used as the acid solution in the microwave leaching process.

27. The method according to claim 14, wherein at least one of the group consisting of sulfuric acid, nitric acid, and hydrochloric acid is used as the acid solution in the microwave leaching process.

28. The method according to claim 15, wherein at least one of the group consisting of sulfuric acid, nitric acid, and hydrochloric acid is used as the acid solution in the microwave leaching process.

29. The method according to claim 12, wherein the microwave leaching process is carried out at a temperature in a range from 15 to 250 C. for a period of time in a range from 0.1 to 20 h.

30. The method according to claim 13, wherein the microwave leaching process is carried out at a temperature in a range from 15 to 250 C. for a period of time in a range from 0.1 to 20 h.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The method developed for the leaching of rare earth elements (REE) in fluorescent lamp waste, which is the subject of this application, is shown in the attached FIGURES.

[0026] FIGURE is a diagram of the process steps representing the method of the invention.

DESCRIPTION OF THE PROCESS STEPS OF THE METHOD

[0027] 101. Procurement of raw materials [0028] 102. Pre-treatment of raw materials [0029] 102.1. Size classification of phosphorus powders [0030] 102.2. Homogenisation of phosphorus powders [0031] 103. Microwave leaching process [0032] 104. Solid-liquid separation

DETAILED DESCRIPTION OF THE EMBODIMENTS

[0033] In this detailed description, the preferred embodiments of the method for the leaching of rare earth elements (REE) in fluorescent lamp waste are explained only for a better understanding of the subject and without any limiting effect.

[0034] The method of the invention that enables the direct leaching of rare earth elements (REE) in the phosphorus dust in a single step, without using the high energy-requiring pre-treatment step of the phosphor dust in the fluorescent lamp waste, includes the process steps of: [0035] Procurement of raw materials (101) [0036] Pre-treatment of raw materials that does not require high energy (102) [0037] Size classification of phosphorus powders (102.1) [0038] Homogenisation of phosphorus powders (102.2) [0039] Microwave leaching process (103), and [0040] Solid-liquid separation (104).

[0041] In the step of procuring the raw materials (101), 1-1000 kg of fluorescent waste phosphorus powder is procured from the recycling facility.

[0042] In the step of pre-treatment of raw materials (102), processes that do not require high energy are included. In process step 102, the size classification (102.1) and homogenisation (102.2) of the phosphorus powders obtained from recycling are performed.

[0043] The step of size classification of phosphorus powders (102.1) is the process of classifying the particle size of phosphorus powder by passing it through 100 m and 45 m sieves.

[0044] The step of homogenisation of phosphorus powders (102.2) includes homogenising the phosphorus powders in a ball mill for 0.1-100 h at a grinding speed of 50 to 5000 rpm and washing them with pure water.

[0045] Microwave leaching process, which allows Tb, La, Ce and Gd metals in blue and green phosphorus and Eu and Y metals in red phosphorus to be taken into solution in a single step (103) is the process of applying microwave leaching to phosphorus powders in 0.01-12 M acid solutions in a volume of 0.1-1000 L at a temperature of 15-250 C. for 0.1-20 h.

[0046] The power applied in the microwave leaching process (103) is not constant. Microwave applications vary between 0-1600 W depending on the specified temperature (15-250 C.). High efficiency REE-loaded solution was obtained by microwave application at different values within the mentioned parameters.

[0047] In the microwave leaching process (103), 0.01-12 M sulphuric acid (H.sub.2SO.sub.4), nitric acid (HNO.sub.3) and hydrochloric acid (HCl) solutions are used.

[0048] The single-step solution of Tb, La, Ce and Gd metals in blue and green phosphorus and Eu and Y metals in red phosphorus is achieved by the application of microwave leaching process (103). With the explained parameters, the solution of rare earth elements in phosphorus powders was achieved in a single process step. As the last step, after the microwave leaching process (103) is performed, solid-liquid separation is performed (104). In the solid-liquid separation (104) process, solids that do not enter the solution are preferably separated by filtration.

TABLE-US-00001 TABLE 1 REE values in solution REE ppm (solute/solution) Y 7000-10000 Eu 100-1000 La 10-500 Ce 10-500 Gd 10-500 Tb 10-500

[0049] When the method of the invention is applied, the final products obtained are solutions containing high concentrations of Y and Eu, as well as La, Ce, Gd and Tb. The table above shows the REE values obtained as a result of the application of the method that is the subject of the invention.