Comprehensive utilization method of beneficiation-metallurgy-chemical combination for germanium-rich lignite

Abstract

A comprehensive utilization method of beneficiation-metallurgy-chemical combination for germanium-rich lignite includes the following steps: 1) germanium-rich lignite sizing and grinding, 2) catalytic pre-oxidation, 3) nitric acid leaching, and 4) recycling and enrichment of germanium solution. The high effective extraction of germanium from the germanium-rich lignite was achieved via a combination of mineral beneficiation, hydrometallurgy, and chemical processing. Meanwhile, a high yield and high degree of depolymerization humic acid product was produced as byproducts. This method could not only effectively avoid high carbon emission and organic resource waste during conventional germanium-rich lignite pyrometallurgical processing, but also could produce humic acid as quality raw materials for metallurgical and agricultural industries, which has advantages of less environmental pollution, high extraction efficiency, and low comprehensive costs.

Claims

1. A beneficiation-metallurgy-chemical combination method for a germanium-rich lignite, comprising the following steps: 1) performing a mineral processing classification on the germanium-rich lignite to remove mud particles to obtain an oversize product, and grinding the oversize product to obtain a raw lignite; 2) mixing the raw lignite, hydrogen peroxide, and a ferrous ion solution to perform a catalytic pre-oxidation, performing a first solid-liquid separation to obtain an activated solution and an activated lignite residue, and returning the activated solution to the catalytic pre-oxidation step for a first recycling, to obtain a first preliminarily enriched germanium bearing solution; 3) performing a germanium leaching on the activated lignite residue with nitric acid, performing a second solid-liquid separation to obtain a germanium bearing solution and a humic acid-rich solid product with a high degree of depolymerization, and returning the germanium bearing solution to the germanium leaching step for a second recycling, to obtain a second preliminarily enriched germanium bearing solution; and 4) performing an adsorption with an anion exchange resin on the first preliminarily enriched germanium bearing solution and the second preliminarily enriched germanium bearing solution separately or on a combination of the first preliminarily enriched germanium bearing solution and the second preliminarily enriched germanium bearing solution, and performing an elution to obtain a germanium-rich solution, wherein a molar ratio of the hydrogen peroxide to ferrous ions in the ferrous ion solution is (35-60):1.

2. The beneficiation-metallurgy-chemical combination method for the germanium-rich lignite according to claim 1, wherein the mineral processing classification is performed by using a fine screen with a pore size of 74 m to 150 m, and a particle size of the raw lignite is controlled to be 150 m or less in the grinding.

3. The beneficiation-metallurgy-chemical combination method for the germanium-rich lignite according to claim 2, wherein the molar ratio of the hydrogen peroxide to the ferrous ions in the ferrous ion solution is (45-50):1.

4. The beneficiation-metallurgy-chemical combination method for the germanium-rich lignite according to claim 2, wherein the germanium leaching is performed under the following conditions: a concentration of the nitric acid is 0.7 mol/L to 1.2 mol/L, a liquid-solid ratio is (8-15) mL:1 g, a leaching duration is 0.5 h to 1 h, and a temperature is 85 C. to 95 C.

5. The beneficiation-metallurgy-chemical combination method for the germanium-rich lignite according to claim 4, wherein a number of cycles for the first recycling or the second recycling is 3 to 5.

6. The beneficiation-metallurgy-chemical combination method for the germanium-rich lignite according to claim 1, wherein the molar ratio of the hydrogen peroxide to the ferrous ions in the ferrous ion solution is (45-50):1.

7. The beneficiation-metallurgy-chemical combination method for the germanium-rich lignite according to claim 1, wherein the catalytic pre-oxidation is performed under the following conditions: a liquid-solid ratio is (8-15) mL:1 g, a temperature is 20 C. to 25 C., a duration is 0.5 h to 1 h, and a concentration of the hydrogen peroxide is 2.0 mol/L to 4.0 mol/L.

8. The beneficiation-metallurgy-chemical combination method for the germanium-rich lignite according to claim 7, wherein the germanium leaching is performed under the following conditions: a concentration of the nitric acid is 0.7 mol/L to 1.2 mol/L, a liquid-solid ratio is (8-15) mL:1 g, a leaching duration is 0.5 h to 1 h, and a temperature is 85 C. to 95 C.

9. The beneficiation-metallurgy-chemical combination method for the germanium-rich lignite according to claim 8, wherein a number of cycles for the first recycling or the second recycling is 3 to 5.

10. The beneficiation-metallurgy-chemical combination method for the germanium-rich lignite according to claim 1, wherein the germanium leaching is performed under the following conditions: a concentration of the nitric acid is 0.7 mol/L to 1.2 mol/L, a liquid-solid ratio is (8-15) mL:1 g, a leaching duration is 0.5 h to 1 h, and a temperature is 85 C. to 95 C.

11. The beneficiation-metallurgy-chemical combination method for the germanium-rich lignite according to claim 10, wherein a number of cycles for the first recycling or the second recycling is 3 to 5.

12. The beneficiation-metallurgy-chemical combination method for the germanium-rich lignite according to claim 1, wherein the anion exchange resin is modified using polyurethane resin, polyvinyl chloride resin, or polypropylene resin.

13. The beneficiation-metallurgy-chemical combination method for the germanium-rich lignite according to claim 12, wherein in the humic acid-rich solid product with the high degree of depolymerization, a humic acid yield of the humic acid-rich solid product is greater than or equal to 45%, and a humic acid ultraviolet characteristic parameter E4/E6 is greater than or equal to 9.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a schematic flowchart of a comprehensive utilization process of beneficiation-metallurgy-chemical combination for germanium-rich lignite according to the present invention.

(2) FIGS. 2A-2B show ultraviolet-visible spectra of humic acid obtained before and after treatment on germanium-rich lignite under same testing conditions according to Embodiment 1 of the present invention, where FIG. 2A shows raw lignite without treatment, and FIG. 2B shows lignite treated by catalytic pre-oxidation and nitric acid leaching according to the present invention.

DETAILED DESCRIPTION OF THE EMBODIMENTS

(3) The following describes the technical solutions in embodiments of the present invention clearly and completely with reference to the accompanying drawings in the embodiments of the present invention. Apparently, the described embodiments are merely some rather than all of the embodiments of the present invention. All other embodiments obtained by a person of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

Embodiment 1

(4) Raw lignite containing 210 g/g of germanium from Yunnan was first sized by using a high-frequency fine screen to remove fine mud particles smaller than a 200 mesh size (74 m), and an oversize product was ground to a particle size of 150 m or less to be used as feedstock for subsequent treatment. The feedstock was taken and subjected to catalytic pre-activation under the following conditions: a concentration of hydrogen peroxide was 3.0 mol/L, a concentration of ferrous ions was 0.06 mol/L (in the solution, H.sub.2O.sub.2/Fe.sup.2+=50:1), a reaction liquid-solid ratio was 10:1, treatment duration was 1 h, and a treatment temperature was room temperature. After the catalytic pre-activation, solid-liquid separation was performed to obtain an activated solution (a) and an activated lignite residue. The activated solution (a) was recycled three times to implement preliminary enrichment. Next, polyurethane-modified anion exchange resin was used to adsorb germanium. Then, germanium elution was performed for enrichment to obtain a preliminarily enriched germanium bearing solution (a). The activated lignite residue obtained at the catalytic activation stage was used for nitric acid leaching.

(5) The activated lignite residue was treated with a 0.8 mol/L nitric acid solution to react for leaching germanium out under the following conditions: a liquid-solid ratio was 10:1, a leaching temperature was controlled to 90 C., and reaction duration was 0.5 h. After leaching, solid-liquid separation was performed to obtain a germanium bearing solution (b) and a humic acid-rich solid product with a high degree of depolymerization. The germanium bearing solution (b) was recycled three times to implement preliminary germanium enrichment. Polypropylene-modified anion exchange resin was used to adsorb germanium. Then, germanium elution was performed for enrichment to obtain a preliminarily enriched germanium bearing solution (b). The preliminarily enriched germanium bearing solution (a) and the preliminarily enriched germanium bearing solution (b) were combined for subsequent germanium extraction.

(6) Through the foregoing treatment, a one-time direct hydrometallurgical extraction rate of germanium from the raw germanium-rich lignite can reach 85.33%, a humic acid yield reaches 49.16% or more, and a humic acid ultraviolet characteristic parameter E4/E6 reaches 9.54.

(7) FIGS. 2A-2B show ultraviolet-visible spectra of humic acid obtained before and after treatment on germanium-rich lignite under same testing conditions according to Embodiment 1 of the present invention, where FIG. 2A shows raw lignite without treatment, and FIG. 2B shows lignite treated by catalytic pre-oxidation and nitric acid leaching according to the present invention. It can be learned from the figure that, through the treatment of the present invention, the obtained humic acid ultraviolet characteristic parameter E4/E6 is significantly increased, and a product with a higher degree of depolymerization is obtained.

Embodiment 2

(8) Other conditions are the same as those in Embodiment 1. The difference lies in that: a concentration of hydrogen peroxide is changed to 2.0 mol/L, and a concentration of ferrous ions is changed to 0.04 mol/L (maintaining H.sub.2O.sub.2/Fe.sup.2+=50:1 in the solution). Other experimental parameters and steps are the same as those in Embodiment 1. Finally, a one-time direct hydrometallurgical extraction rate of germanium is 80.34%, a humic acid yield is 45.37%, and a degree of depolymerization E4/E6 of humic acid is 9.06.

(9) Compared with Embodiment 1, with the same liquid-solid ratio in this embodiment, as the concentration of hydrogen peroxide changes, the concentration of ferrous ions changes, and a concentration of hydroxyl radicals in the solution also changes, affecting catalytic oxidation of the germanium-rich lignite, and consequently affecting the extraction rate and the yield.

Embodiment 3

(10) Other conditions are the same as those in Embodiment 1. The difference lies in that: a concentration of nitric acid is changed to 1.2 mol/L. Other experimental parameters and steps are the same as those in Embodiment 1. Finally, recovery of germanium is 86.50%, a humic acid yield is 47.25%, and a degree of depolymerization E4/E6 of humic acid is 9.13.

Embodiment 4

(11) Other conditions are the same as those in Embodiment 1. The difference lies in that: a liquid-solid ratio for nitric acid leaching is changed to 12.5:1. Other experimental parameters and steps are the same as those in Embodiment 1. Finally, recovery of germanium is 80.96%, a humic acid yield is 47.06%, and a degree of depolymerization E4/E6 of humic acid is 9.28.

Embodiment 5

(12) Raw lignite containing 210 g/g of germanium from Yunnan was first sized by using a high-frequency fine screen to remove fine mud particles smaller than a 150 mesh size (100 m), and an oversize product was ground to a particle size of 150 m or less to be used as feedstock for subsequent treatment. The feedstock was taken and subjected to catalytic pre-activation under the following conditions: a concentration of hydrogen peroxide was 3.0 mol/L, a concentration of ferrous ions was 0.06 mol/L (in the solution, H.sub.2O.sub.2/Fe.sup.2+=50:1), a reaction liquid-solid ratio was 9:1, treatment duration was 0.6 h, and a treatment temperature was room temperature. After the catalytic pre-activation, solid-liquid separation was performed to obtain an activated solution (a) and an activated lignite residue. The activated solution (a) was recycled four times to implement preliminary enrichment. Next, polyurethane-modified anion exchange resin was used to adsorb germanium. Then, germanium elution was performed for enrichment to obtain a preliminarily enriched germanium bearing solution (a). The activated lignite residue obtained at the catalytic activation stage was used for nitric acid leaching.

(13) The activated lignite residue was treated with a 0.8 mol/L nitric acid solution to react for leaching germanium out under the following conditions: a liquid-solid ratio was 11:1, a leaching temperature was controlled to 92 C., and reaction duration was 0.6 h. After leaching, solid-liquid separation was performed to obtain a germanium bearing solution (b) and a humic acid-rich solid product with a high degree of depolymerization. The germanium bearing solution (b) was recycled four times to implement preliminary germanium enrichment. Polypropylene-modified anion exchange resin was used to adsorb germanium. Then, germanium elution was performed for enrichment to obtain a preliminarily enriched germanium bearing solution (b). The preliminarily enriched germanium bearing solution (a) and the preliminarily enriched germanium bearing solution (b) were combined for subsequent germanium extraction.

(14) Through the foregoing treatment, a one-time direct hydrometallurgical extraction rate of germanium from the raw germanium-rich lignite can reach 84.61%, a humic acid yield reaches 48.02% or more, and a humic acid ultraviolet characteristic parameter E4/E6 reaches 9.33.

Comparative Example 1

(15) Other conditions are the same as those in Embodiment 1. The difference lies in that: raw lignite was not sized by using a high-frequency fine screen to remove fine mud particles smaller than a 200 mesh size (74 m). Other experimental parameters and steps are the same as those in Embodiment 1. Finally, recovery of germanium is 79.58%, a humic acid yield is 43.07%, and a degree of depolymerization E4/E6 of humic acid is 6.93.

Comparative Example 2

(16) Other conditions are the same as those in Embodiment 1. The difference lies in that: a concentration of ferrous ions is changed to 0.04 mol/L (in the solution, H.sub.2O.sub.2/Fe.sup.2+=75:1). Other experimental parameters and steps are the same as those in Embodiment 1. Finally, recovery of germanium is 64.00%, a humic acid yield is 35.64%, and a degree of depolymerization E4/E6 of humic acid is 7.42.

Comparative Example 3

(17) Other conditions are the same as those in Embodiment 1. The difference lies in that: a concentration of ferrous ions is changed to 0.12 mol/L (in the solution, H.sub.2O.sub.2/Fe.sup.2+=25:1). Other experimental parameters and steps are the same as those in Embodiment 1. Finally, recovery of germanium is 67.26%, a humic acid yield is 32.29%, and a degree of depolymerization E4/E6 of humic acid is 7.17.

Comparative Example 4

(18) Other conditions are the same as those in Embodiment 1. The difference lies in that: a concentration of nitric acid is changed to 0.6 mol/L. Other experimental parameters and steps are the same as those in Embodiment 1. Finally, recovery of germanium is 64.34%, a humic acid yield is 37.94%, and a degree of depolymerization E4/E6 of humic acid is 8.25.

Comparative Example 5

(19) Other conditions are the same as those in Embodiment 1. The difference lies in that: a temperature for nitric acid leaching is changed to 70 C. Other experimental parameters and steps are the same as those in Embodiment 1. Finally, recovery of germanium is 40.06%, a humic acid yield is 39.26%, and a degree of depolymerization E4/E6 of humic acid is 8.74.

Comparative Example 6

(20) Other conditions are the same as those in Embodiment 1. The difference lies in that: feedstock is not subjected to catalytic pre-oxidation but is directly treated with a 1 mol/L nitric acid solution for leaching. Other experimental parameters and steps are the same as those in Embodiment 1. Finally, recovery of germanium is 57.95%, a humic acid yield is 43.19%, and a degree of depolymerization E4/E6 of humic acid is 9.06.

(21) The foregoing descriptions are merely specific preferred implementations of the present invention and some cases in the technological exploration process of the present invention, but are not intended to limit the protection scope of the present invention. Any variation or replacement readily figured out by a person skilled in the art within the technical scope disclosed in the present invention shall fall within the protection scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.