Method for extracting, separating and recovering aluminum, iron and gallium from fly ash sulfuric acid leaching solution step by step

Abstract

The invention relates to the technical field of hydrometallurgy, and particularly discloses a method for extracting, separating and recovering aluminum, iron and gallium from a fly ash sulfuric acid leaching solution step by step. According to the performance difference between the extraction effect and the reverse extraction effect of a mixed organic phase of N1923-sulfonated kerosene, TRPO-sulfonated kerosene and di (nonylphenyl) phosphate-sulfonated kerosene and aluminum, iron and gallium elements, total extraction separation of aluminum, iron and gallium in the fly ash sulfuric acid leaching solution is achieved in a step-by-step extraction and reverse extraction mode. The method has the advantages of simplicity and convenience in operation, easiness in industrialization, environment friendliness and the like.

Description

Technical Field

[0001] The present invention relates to the technical field of hydrometallurgy, and particularly relates to a method for stepwise extraction and separation and recovery of aluminum, iron, and gallium from a sulfuric acid leaching solution of fly ash. Background Art

[0002] The rare metal gallium is an indispensable strategic metal element widely used in semiconductor materials. Due to its characteristics as a rare metal, there is generally no independent ore deposit, and it mostly occurs in other minerals in an associated form, such as bauxite, lead-zinc ore, and coal mines. During the combustion process of gallium-containing coal, gallium further occurs in fly ash. Therefore, fly ash is an important raw material for recovering and extracting gallium. To achieve the leaching of gallium therein, the sulfuric acid leaching method is a commonly used technology. During the acid leaching process, Ga mainly enters the sulfuric acid leaching solution, and at the same time, there are also relatively high concentrations of Al, Fe, and a small amount of elements such as Zn, Cu, K, and Mg that are also leached. Therefore, how to achieve the separation and recovery of Ga, Al, and Fe in the leaching solution is of great significance for the resource utilization of fly ash. Although the solvent extraction method is a commonly used and easy-to-operate and industrializable method for separating and extracting metals in a solution, the current extraction agent system and extraction method are both difficult to be applicable to the extraction and separation and recovery of aluminum, iron, and gallium in this leaching solution, which greatly restricts the comprehensive recovery and utilization of aluminum, iron, and gallium in fly ash.

[0003] In view of this, the present invention is proposed. Summary of the Invention

[0004] The present invention solves the above problems existing in the prior art. The purpose of the present invention is to provide a method for stepwise extraction and separation and recovery of aluminum, iron, and gallium from a sulfuric acid leaching solution of fly ash, and realizes the efficient separation and recovery of aluminum, iron, and gallium by a full extraction method directly from the sulfuric acid leaching solution of fly ash.

[0005] A method for stepwise extraction and separation and recovery of aluminum, iron, and gallium from a sulfuric acid leaching solution of fly ash proposed by the present invention includes the following steps:

[0006] (1) Countercurrent extraction is carried out using a first organic phase and a sulfuric acid leaching solution of fly ash to obtain a primary organic phase and a primary raffinate. The first organic phase is composed of N1923 and sulfonated kerosene. Among them, the sulfuric acid leaching solution of fly ash contains Ga 3+ 0.1 - 0.5 g / L, Fe 3+ 3 - 5 g / L, Al 3+ 5 - 10 g / L, Mg 2+ , K + , Ca 2+ all less than 1.0 g / L, and the pH value is 0 - 1.5;

[0007] (2) The primary organic phase is subjected to counter-current stripping with hydrochloric acid to obtain a secondary organic phase and an aluminum-iron-gallium stripping solution. After the secondary organic phase is washed with a clarified lime water solution until the pH = 7, it is returned to step (1) as the primary organic phase for recycling.

[0008] (3) The secondary organic phase is used for counter-current extraction with the aluminum-iron-gallium stripping solution to obtain a tertiary organic phase and an aluminum raffinate. The secondary organic phase is composed of TRPO and sulfonated kerosene.

[0009] (4) The tertiary organic phase is subjected to counter-current stripping with nitric acid to obtain a quaternary organic phase and an iron-gallium stripping solution. After the quaternary organic phase is washed with deionized water solution until the pH = 7, it is returned to step (3) as the secondary organic phase for recycling.

[0010] (5) The tertiary organic phase is used for counter-current extraction with the iron-gallium stripping solution to obtain a quinary organic phase and a gallium raffinate. The tertiary organic phase is composed of bis(nonylphenyl) phosphate and sulfonated kerosene.

[0011] (6) The quinary organic phase is subjected to counter-current stripping with oxalic acid to obtain a senary organic phase and an iron stripping solution. After the senary organic phase is washed with deionized water solution until the pH = 7, it is returned to step (5) as the tertiary organic phase for recycling.

[0012] Preferably, the primary organic phase in step (1) is composed of the following components by volume fraction: 10% - 30% N1923 and 70% - 90% sulfonated kerosene.

[0013] Preferably, in step (1), the extraction phase ratio O / A of the cross-flow extraction is 1 - 3:1, the extraction stage number is 1 - 3 stages, and the extraction time is 5 - 10 min.

[0014] Preferably, the concentration of the hydrochloric acid in step (2) is 5 - 6 mol / L, the stripping phase ratio A / O of the counter-current stripping is 1 - 3:1, the stripping stage number is 2 - 3 stages, and the stripping time is 5 - 10 min.

[0015] Preferably, the secondary organic phase in step (3) is composed of the following components by volume fraction: 10% - 30% TRPO and 70% - 90% sulfonated kerosene.

[0016] Preferably, in step (3), the extraction phase ratio O / A of the counter-current extraction is 1 - 3:1, the extraction stage number is 2 - 3 stages, and the extraction time is 5 - 10 min.

[0017] Preferably, the molar concentration of the nitric acid in step (4) is 2 - 4 mol / L, the stripping phase ratio A / O of the counter-current stripping is 1 - 3:1, the stripping stage number is 2 - 3 stages, and the stripping time is 5 - 10 min.

[0018] Preferably, the third organic phase in step (5) is composed of the following components by volume fraction: 10% - 20% bis(nonylphenyl) phosphate and 80% - 90% sulfonated kerosene.

[0019] Preferably, for the countercurrent extraction in step (5), the extraction phase ratio O / A is 1 - 2:1, the number of extraction stages is 1 - 2, and the extraction time is 5 - 10 min.

[0020] Preferably, the molar concentration of oxalic acid in step (6) is 0.5 - 1.0 mol / L; for the countercurrent stripping, the stripping phase ratio A / O is 1 - 2:1, the number of stripping stages is 3 - 5, and the stripping time is 5 - 10 min.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] The present invention provides a method for stepwise extraction and separation to recover aluminum, iron, and gallium from the sulfuric acid leaching solution of fly ash. This method cleverly utilizes the performance differences in the extraction and stripping effects of the mixed organic phases of N1923 - sulfonated kerosene, TRPO - sulfonated kerosene, and bis(nonylphenyl) phosphate - sulfonated kerosene with aluminum, iron, and gallium elements under different acidic systems, and realizes the complete extraction and separation of aluminum, iron, and gallium in the sulfuric acid leaching solution of fly ash through stepwise extraction and stripping. This method has the advantages of simple operation, easy industrialization, and environmental friendliness, providing technical support for the comprehensive recovery and utilization of fly ash by wet full extraction. Specific Embodiments

[0023] The following examples are further illustrations of the present invention rather than limitations thereof. Unless otherwise specified, the equipment and reagents used in the present invention are conventional commercially available products in this technical field.

[0024] Example 1

[0025] The composition of the sulfuric acid leaching solution of fly ash is shown in Table 1:

[0026] Table 1

[0027]

[0028] A method for stepwise extraction and separation to recover aluminum, iron, and gallium from the sulfuric acid leaching solution of fly ash, comprising the following steps:

[0029] (1) Using the first organic phase and the sulfuric acid leaching solution of fly ash, with an extraction phase ratio O / A of 2:1 and an extraction time of 10 min, perform 3 - stage cross - flow extraction to obtain a primary organic phase and a primary raffinate. The extraction rates of aluminum, iron, and gallium are all 100%, and the extraction rates of other ions are <5%. The first organic phase is composed of 10% N1923 + 90% sulfonated kerosene by volume fraction;

[0030] (2) The stripping ratio of the primary organic phase to 6 mol / L hydrochloric acid is A / O = 1:1, the stripping time is 10 min, and three-stage countercurrent stripping is carried out to obtain the secondary organic phase and the aluminum-iron-gallium stripping solution. The stripping rates of aluminum, iron, and gallium are all 100%. After the secondary organic phase is washed with clarified lime water solution to pH = 7, it is returned to step (1) and recycled as the first organic phase;

[0031] (3) The second organic phase and the aluminum-iron-gallium stripping solution are used for three-stage countercurrent extraction with an extraction ratio of O / A = 1:1 and an extraction time of 10 min to obtain the tertiary organic phase and the aluminum raffinate. The extraction rates of gallium and iron are both 100%, and the extraction rate of aluminum is only 3.23%. By volume, the second organic phase consists of 30% TRPO and 70% sulfonated kerosene;

[0032] (4) The tertiary organic phase and 2 mol / L nitric acid are used for three-stage countercurrent stripping with a stripping ratio of A / O = 3:1 and a stripping time of 10 min to obtain the quaternary organic phase and the iron-gallium stripping solution. The stripping rate of gallium is 99.95% and the stripping rate of iron is 99.82%. After the quaternary organic phase is washed with deionized water solution to pH = 7, it is returned to step (3) and recycled as the second organic phase;

[0033] (5) The third organic phase and the iron-gallium stripping solution are used for two-stage countercurrent extraction with an extraction ratio of O / A = 1:1 and an extraction time of 10 min to obtain the fifth organic phase and the gallium raffinate. The extraction rate of iron is 98.23% and the extraction rate of gallium is only 7.89%. By volume, the third organic phase consists of 10% bis(nonylphenyl) phosphate and 90% sulfonated kerosene;

[0034] (6) The fifth organic phase and 0.5 mol / L oxalic acid solution are used for three-stage countercurrent stripping with a stripping ratio of A / O = 2:1 and a stripping time of 10 min to obtain the sixth organic phase and the iron stripping solution. The stripping rate of iron is 98.32%. After the sixth organic phase is washed with deionized water solution to pH = 7, it is returned to step (5) and recycled as the third organic phase.

[0035] Example 2

[0036] The composition of the fly ash sulfuric acid leaching solution is shown in Table 2:

[0037] Table 2

[0038]

[0039] A method for stepwise extraction and separation and recovery of aluminum, iron, and gallium from fly ash sulfuric acid leaching solution, comprising the following steps:

[0040] (1) The first organic phase and the sulfuric acid leaching solution of fly ash are subjected to 1-stage cross-flow extraction with an extraction ratio of O / A of 1:1 and an extraction time of 10 min to obtain a primary organic phase and a primary raffinate. The extraction rates of aluminum, iron, and gallium are all greater than 99%, and the extraction rates of other ions are <5%. By volume fraction, the first organic phase consists of 30% N1923 + 70% sulfonated kerosene;

[0041] (2) Take the primary organic phase and 6 mol / L hydrochloric acid for 2-stage counter-current stripping with a stripping ratio of A / O of 3:1 and a stripping time of 5 min to obtain a secondary organic phase and an aluminum, iron, and gallium stripping solution. The stripping rates of aluminum, iron, and gallium are all greater than 97%. After the secondary organic phase is washed with a clarified lime water solution to pH = 7, it is returned to step (1) as the first organic phase for recycling;

[0042] (3) The second organic phase and the aluminum, iron, and gallium stripping solution are subjected to 2-stage counter-current extraction with an extraction ratio of O / A of 3:1 and an extraction time of 10 min to obtain a tertiary organic phase and an aluminum raffinate. The extraction rates of gallium and iron are both 100%, and the extraction rate of aluminum is only 4.39%. By volume fraction, the second organic phase consists of 10% TRPO and 90% sulfonated kerosene;

[0043] (4) Take the tertiary organic phase and 4 mol / L nitric acid for 3-stage counter-current stripping with a stripping ratio of A / O of 1:1 and a stripping time of 10 min to obtain a quaternary organic phase and a gallium and iron stripping solution. The stripping rate of gallium is 98.25% and the stripping rate of iron is 98.73%. After the quaternary organic phase is washed with deionized water solution to pH = 7, it is returned to step (3) as the second organic phase for recycling;

[0044] (5) The third organic phase and the gallium and iron stripping solution are subjected to 1-stage counter-current extraction with an extraction ratio of O / A of 1:1 and an extraction time of 10 min to obtain a quinary organic phase and a gallium raffinate. The extraction rate of iron is 100%, and the extraction rate of gallium is only 7.12%. By volume fraction, the third organic phase consists of 20% bis(nonylphenyl) phosphate and 80% sulfonated kerosene;

[0045] (6) Take the quinary organic phase and 1.0 mol / L oxalic acid solution for 5-stage counter-current stripping with a stripping ratio of A / O of 1:1 and a stripping time of 5 min to obtain a senary organic phase and an iron stripping solution. The stripping rate of iron is 98.69%. After the senary organic phase is washed with deionized water solution to pH = 7, it is returned to step (5) as the third organic phase for recycling.

[0046] Example 3

[0047] The composition of the sulfuric acid leaching solution of fly ash is shown in Table 3:

[0048] Table 3

[0049]

[0050] A method for stepwise extraction, separation and recovery of aluminum, iron and gallium from sulfuric acid leaching solution of fly ash, comprising the following steps:

[0051] (1) Using a first organic phase and the sulfuric acid leaching solution of fly ash with an extraction ratio of O / A of 1:1 and an extraction time of 5 min, perform 1-stage cross-flow extraction to obtain a primary organic phase and a primary raffinate. The extraction rates of aluminum, iron and gallium are all 100%, and the extraction rates of other ions are <5% (by volume fraction). The first organic phase consists of 30% N1923 + 70% sulfonated kerosene;

[0052] (2) Take the primary organic phase and 5 mol / L hydrochloric acid with a stripping ratio of A / O of 3:1 and a stripping time of 5 min, perform 3-stage countercurrent stripping to obtain a secondary organic phase and an aluminum, iron and gallium stripping solution. The stripping rates of aluminum, iron and gallium are all 100%. After the secondary organic phase is washed with clarified lime water solution to pH = 7, it is returned to step (1) as the first organic phase for recycling;

[0053] (3) Using a second organic phase and the aluminum, iron and gallium stripping solution with an extraction ratio of O / A of 2:1 and an extraction time of 5 min, perform 3-stage countercurrent extraction to obtain a tertiary organic phase and an aluminum raffinate. The extraction rate of gallium is 98.73%, the extraction rate of iron is 99.02%, and the extraction rate of aluminum is only 4.47% (by volume fraction). The second organic phase consists of 15% TRPO and 85% sulfonated kerosene;

[0054] (4) Take the tertiary organic phase and 3 mol / L nitric acid with a stripping ratio of A / O of 3:1 and a stripping time of 5 min, perform 3-stage countercurrent stripping to obtain a quaternary organic phase and an iron and gallium stripping solution. The stripping rate of gallium is 99.35% and the stripping rate of iron is 99.78%. After the quaternary organic phase is washed with deionized water solution to pH = 7, it is returned to step (3) as the second organic phase for recycling;

[0055] (5) Using a third organic phase and the iron and gallium stripping solution with an extraction ratio of O / A of 2:1 and an extraction time of 5 min, perform 1-stage countercurrent extraction to obtain a quinary organic phase and a gallium raffinate. The extraction rate of iron is 98.79%, and the extraction rate of gallium is only 7.25% (by volume fraction). The third organic phase consists of 15% bis(nonylphenyl) phosphate and 85% sulfonated kerosene;

[0056] (6) Take the quinary organic phase and 1.0 mol / L oxalic acid solution with a stripping ratio of A / O of 2:1 and a stripping time of 5 min, perform 5-stage countercurrent stripping to obtain a senary organic phase and an iron stripping solution. The stripping rate of iron is 99.83%. After the senary organic phase is washed with deionized water solution to pH = 7, it is returned to step (5) as the third organic phase for recycling.

[0057] Comparative Example 1

[0058] This comparative example is basically the same as Example 1, except that: in the first organic phase, the similar extractant N235 is used to replace N1923, and the extraction rates of Ga and aluminum are both less than 30%, and the stepwise extraction and separation and recovery of aluminum, iron and gallium in the sulfuric acid leaching solution of fly ash cannot be achieved.

[0059] Comparative Example 2

[0060] This comparative example is basically the same as Example 1, except that: nitric acid is used to replace hydrochloric acid, and the first organic phase is stripped with 6 mol / L nitric acid to obtain the stripping solution of aluminum, iron and gallium; the second organic phase is used to extract the stripping solution of aluminum, iron and gallium, and the extraction rates of Ga and iron are both less than 15%, and the stepwise extraction and separation and recovery of aluminum, iron and gallium in the sulfuric acid leaching solution of fly ash cannot be achieved.

[0061] Comparative Example 3

[0062] This comparative example is basically the same as Example 2, except that: in the second organic phase, the similar extractant P350 is used to replace TRPO, the iron extraction rate is only 4.52%, and the Ga extraction rate is only 69.18%, and the stepwise extraction and separation and recovery of aluminum, iron and gallium in the sulfuric acid leaching solution of fly ash cannot be achieved.

[0063] Comparative Example 4

[0064] This comparative example is basically the same as Example 2, except that: sulfuric acid is used to replace nitric acid, and the third organic phase is stripped with 4 mol / L sulfuric acid to obtain the stripping solution of iron and gallium; the third organic phase is used to extract the stripping solution of iron and gallium, and the iron extraction rate is only 62.76%, and the stepwise extraction and separation and recovery of aluminum, iron and gallium in the sulfuric acid leaching solution of fly ash cannot be achieved.

[0065] Comparative Example 5

[0066] This comparative example is basically the same as Example 3, except that: in the third organic phase, the similar extractant Cyanex272 is used to replace bis(nonylphenyl) phosphate, and the iron extraction rate is only 45.58%, and the stepwise extraction and separation and recovery of aluminum, iron and gallium in the sulfuric acid leaching solution of fly ash cannot be achieved.

[0067] Comparative Example 6

[0068] This comparative example is basically the same as Example 3, except that: nitric acid is used to replace oxalic acid, and the fifth organic phase is stripped with 1.0 mol / L nitric acid solution, and the iron stripping rate is only 10.35%, and the stepwise extraction and separation and recovery of aluminum, iron and gallium in the sulfuric acid leaching solution of fly ash cannot be achieved.

[0069] By comparing the examples with each comparative example, it can be seen that none of the comparative examples can achieve the stepwise extraction and separation effect of aluminum, iron, and gallium in the examples. Thus, it can be demonstrated that the extraction system and extraction process for the stepwise extraction and separation and recovery of aluminum, iron, and gallium from the sulfuric acid leaching solution of fly ash in the present invention are not simply a combination of extractants and extraction processes or a conventional substitution of the same type, but have an unexpected and significantly synergistic effect; and when the extraction method, number of stages, time, etc. are within the scope required by the present invention, the extraction and separation effects of each metal can be further ensured.

[0070] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, various changes and modifications can be made to the present invention. Any modification, equivalent substitution, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A method for recovering aluminum, iron and gallium from fly ash sulfuric acid leachate by stepwise extraction and separation, characterized in that: The steps include: (1) A first organic phase and a fly ash sulfuric acid leaching solution are subjected to cross-current extraction to obtain a primary organic phase and a primary raffinate, wherein the first organic phase is composed of N1923 and sulfonated kerosene, and the fly ash sulfuric acid leaching solution contains Ga 3+ 0.1~0.5g / L,Fe 3+ 3~5g / L,Al 3+ 5~10g / L, Mg 2+ , K + , Ca 2+ All are less than 1.0 g / L, and the pH value is 0 to 1.5; (2) taking the primary organic phase and conducting countercurrent stripping with hydrochloric acid to obtain a secondary organic phase and an aluminum-iron-gallium stripping solution, and washing the secondary organic phase with a clarified lime solution to a pH of 7 and then returning to step (1) for recycling as the first organic phase; (3) using the second organic phase and the aluminum-iron-gallium stripping solution to perform countercurrent extraction to obtain a tertiary organic phase and an aluminum raffinate, wherein the second organic phase is composed of TRPO and sulfonated kerosene; (4) taking the three organic phases and performing countercurrent stripping with nitric acid to obtain the fourth organic phase and the iron-gallium stripping solution, washing the fourth organic phase with a deionized water solution to a pH of 7 and then returning to step (3) for recycling as the second organic phase; (5) using the third organic phase and the iron-gallium stripping solution to perform countercurrent extraction to obtain a fifth organic phase and a gallium raffinate, wherein the third organic phase is composed of di(nonylphenyl) phosphate and sulfonated kerosene; (6) taking the fifth organic phase and conducting countercurrent stripping with oxalic acid to obtain a sixth organic phase and an iron stripping solution; the sixth organic phase is washed with a deionized water solution to a pH of 7 and then returned to step (5) for recycling as the third organic phase.

2. The method for recovering aluminum, iron and gallium from fly ash sulfuric acid leachate by step-by-step extraction and separation according to claim 1, characterized in that: The first organic phase described in step (1) is composed of the following components by volume fraction: 10% to 30% N1923 and 70% to 90% sulfonated kerosene.

3. The method for recovering aluminum, iron and gallium from fly ash sulfuric acid leachate by step-by-step extraction and separation according to claim 1, characterized in that: The extraction phase ratio O / A of the cross-current extraction in step (1) is 1 to 3:1, the number of extraction stages is 1 to 3, and the extraction time is 5 to 10 minutes.

4. The method for recovering aluminum, iron and gallium from fly ash sulfuric acid leachate by stepwise extraction and separation according to claim 1, characterized in that: The concentration of the hydrochloric acid in step (2) is 5-6 mol / L, the countercurrent stripping ratio A / O is 1-3:1, the stripping stage is 2-3, and the stripping time is 5-10 min.

5. The method for recovering aluminum, iron and gallium from fly ash sulfuric acid leachate by step-by-step extraction and separation according to claim 1, characterized in that: The second organic phase in step (3) is composed of the following components by volume: 10% to 30% TRPO and 70% to 90% sulfonated kerosene.

6. The method for recovering aluminum, iron and gallium from fly ash sulfuric acid leaching solution by step-by-step extraction and separation according to claim 1, characterized in that: The extraction phase ratio O / A of the countercurrent extraction in step (3) is 1 to 3:1, the number of extraction stages is 2 to 3, and the extraction time is 5 to 10 minutes.

7. The method for recovering aluminum, iron and gallium from fly ash sulfuric acid leaching solution by step-by-step extraction and separation according to claim 1, characterized in that: The molar concentration of the nitric acid in step (4) is 2-4 mol / L, the stripping phase ratio A / O of the countercurrent stripping is 1-3:1, the stripping stage is 2-3, and the stripping time is 5-10 min.

8. The method for recovering aluminum, iron and gallium from fly ash sulfuric acid leachate by step-by-step extraction and separation according to claim 1, characterized in that: The third organic phase in step (5) is composed of the following components by volume fraction: 10% to 20% of di(nonylphenyl) phosphate and 80% to 90% of sulfonated kerosene.

9. The method for recovering aluminum, iron and gallium from fly ash sulfuric acid leaching solution by step-by-step extraction and separation according to claim 1, characterized in that: The extraction phase ratio O / A of the countercurrent extraction in step (5) is 1 to 2:1, the number of extraction stages is 1 to 2, and the extraction time is 5 to 10 minutes.

10. The method for recovering aluminum, iron and gallium from fly ash sulfuric acid leachate by step-by-step extraction and separation according to claim 1, characterized in that: The molar concentration of oxalic acid in step (6) is 0.5-1.0 mol / L: the countercurrent stripping phase ratio A / O is 1-2:1, the stripping stage is 3-5, and the stripping time is 5-10 min.

Images