CN107815541A - The Fe loaded in hydrofluoric acid back extraction P204 organic phases3+And the method for strip liquor processing - Google Patents

Abstract

The invention relates to a method for back-extracting Fe ³⁺ loaded in P204 organic phase with hydrofluoric acid and treating the back-extraction solution, and belongs to the technical field of hydrometallurgy. The P204 organic phase loaded with Fe ³⁺ is back-extracted with hydrofluoric acid solution, and the iron-rich back-extraction solution is neutralized and precipitated with lime slurry to remove iron and F ^‑ , and the obtained iron-poor back-extraction solution is directly returned to the system for washing and back-extraction to remove iron The final P204 organic phase, or continue to return to the stripping process after supplementing with hydrofluoric acid, and the components of the precipitated slag are ferric hydroxide and calcium fluoride, which are recycled as slagging agents in the nickel-iron pyrometallurgy process. The method achieves the effect of no waste residue and waste liquid discharge while reducing the cost of stripping, and is environmentally friendly and zero discharge.

Description

Hydrofluoric acid back-extraction of Fe3+ loaded in the organic phase of P204 and the method of back-extraction liquid treatment

technical field

The invention relates to a method for back-extracting Fe ³⁺ loaded in P204 organic phase with hydrofluoric acid and treating the back-extraction liquid, and belongs to the technical field of hydrometallurgy.

Background technique

P204 is an acidic phosphorus-type extractant, the Chinese name is two (2-ethylhexyl) phosphoric acid, and it is widely used in the hydrometallurgy of non-ferrous metals, such as the separation of nickel and cobalt, extraction of zinc, extraction of indium, nickel, cobalt Extraction and removal of impurities and rare earth extraction and grouping in the refining process.

In the process of using P204 for extraction, separation of metals, or extraction and removal of impurities, some iron ion impurities are unavoidable in the aqueous phase feed liquid, and P204 has a strong ability to extract Fe(III). Fe(III) in the organic phase is difficult to be completely back-extracted under certain conditions. Therefore, during the recycling of the P204 organic phase, Fe(III) will be enriched in the organic phase, and then the P204 organic phase will be extracted and separated. The ability is reduced; in industrial applications, some people call it "poisoning" of the P204 organic phase; for this reason, how to strip and remove iron from the P204 organic phase loaded with Fe(III) has always been concerned.

Due to the strong stability of Fe(III) in the P204 organic phase, it cannot be effectively stripped even with high-concentration sulfuric acid. At present, the most commonly used stripping agent in industry is hydrochloric acid solution with a concentration of about 6mol/L, and it is also available in The industrial application of adding alkali metal or alkaline earth metal chloride to the hydrochloric acid solution to strip iron; the main disadvantage of using a hydrochloric acid solution of about 6mol/L or a mixed solution of hydrochloric acid and chloride for stripping is that the stripping agent has a large acid mist and the operating conditions Poor; in addition, the hydrochloric acid in the stripping agent is generally far excessive. During the recycling process, the iron ion concentration in the stripping solution gradually increases, and the free acidity decreases. When the free hydrochloric acid concentration drops to about 5mol/L, the effect of stripping iron It can only be discharged as waste acid and replaced with a new stripping agent; in this case, the consumption of stripping agent is large, and a large amount of free hydrochloric acid in the waste acid is not fully utilized, and the neutralization of the waste acid is difficult. It will bring a large amount of neutralized waste residue, which is easy to pollute the environment.

In view of this, the patent application No. 200610152788.3 proposes to add NaOH solution in the P204 regenerated by hydrochloric acid, so that the Fe in the P204 organically forms Fe( ^OH ) ₃ , and after precipitation, the sediment Fe(OH) ₃ is discarded , to regenerate iron-containing P204; this method still uses high-concentration hydrochloric acid for regeneration, and then uses sodium hydroxide for deep regeneration. During the process, Fe(OH) ₃ is precipitated, which is prone to emulsification and three-phase matter, and it is difficult to separate the two phases. No regenerative operation is utilized.

The patent application with the application number 201210036114.2 proposes that the P204 organic phase is first regenerated by back extraction with 6mol/L hydrochloric acid, and then undergoes alkaline washing with aqueous solution of sodium hydroxide + ammonium bicarbonate, and pickling with aqueous solution of oxalic acid + sulfuric acid. The whole process still cannot get rid of the 6mol/L With the use of L hydrochloric acid stripping agent, it is difficult to treat the iron-containing hydrochloric acid waste liquid, and after the 6mol/L hydrochloric acid stripping treatment, an additional stage of alkali washing and a stage of pickling are added. The overall process consumes a lot of acid and alkali, and the cost of waste acid and alkali Subsequent processing is difficult.

Patent No. 93111639.2 uses 2-4mol/L NH ₄ F as the stripping agent, and adds ammonia water to the (NH ₄ ) ₃ FeF ₆ obtained in the iron stripping process to adjust the pH to 7-9 to convert it into Fe( OH) ₃ precipitation, while NH ₄ F is regenerated and returned to use; one of its disadvantages is that (NH ₄ ) ₃ FeF ₆ precipitates are generated during the stripping process, which brings inconvenience to the stripping operation; in addition, the use of F-containing reagents in the process It is easy to cause fluorine hazards to the environment, such as Fe(OH) ₃ precipitation entraining fluorine-containing solution is easy to pollute the environment.

The patent application with the application number 201210164356.X discloses a method for eluting Fe in the P204 extractant; the method is based on the stability of the complex generated by the reaction of Fe ²⁺ with the P204 extractant is lower than that of ^{Fe 3+} The first principle is to achieve the purpose of eluting Fe ³⁺ in the poisoned extractant by adding a reducing agent. The process principle adopted is essentially reduction and stripping; The agent is sodium borohydride, phosphorous acid, hydroxylamine hydrochloride or oxalic acid, and the reduction and stripping time is 0.5 to 2 hours; due to the limitation of the reduction and stripping method itself, a higher stripping temperature must be used, which will inevitably cause volatilization loss of the organic phase , also did not provide the treatment method of iron-containing waste acid.

The patent application with the application number 201410155947.X discloses a method for back-extracting the P204 organic phase loaded with iron and removing iron from the back-extraction solution. The stripping solution adopts photodecomposition to selectively precipitate and remove iron. When sunlight is used for precipitation to remove iron, the time required for sunlight is 4 to 12 hours. Too long reaction time is not conducive to popularization and use in production; when iron powder is added for reduction and precipitation When removing iron, the amount of iron powder added is 2 to 4 times the mass of iron in the iron-rich stripping solution by mass ratio. If the amount of iron powder added is too large, the cost is too high; the temperature during reduction precipitation and iron removal needs to be controlled at 60 ~90°C, the time for iron removal by precipitation is 4~12h, and the liquid after iron removal must be cooled before returning to the system for use. The energy consumption is too high, the reaction time is too long, and the requirements for high temperature resistance and corrosion resistance of the equipment are also high. It is difficult to popularize and use in production; the treatment method of ferrous oxalate has not been given.

Contents of the invention

For the P204 organic phase of existing loaded iron, the above-mentioned problems that exist in the stripping technology, the present invention provides a kind of hydrofluoric acid stripping loaded Fe3 ⁺ P204organic phase and the method for iron removal recycling of stripping solution, the method It can achieve the effect of no waste residue and waste liquid discharge while reducing the cost of stripping, which is green and environmentally friendly, and has zero discharge.

The method for the hydrofluoric acid stripping loaded Fe3 ⁺ P204 organic phase and stripping solution for iron removal recycling of the present invention adopts hydrofluoric acid solution complexation stripping Fe3 ⁺ loaded P204 organic phase, iron-rich stripping solution Use lime slurry to neutralize and precipitate to remove iron and F ^- , and the obtained iron-poor stripping solution is directly returned to the system to wash the P204 organic phase after stripping and iron removal, or continue to return to the stripping process for use after supplementing hydrofluoric acid, and the precipitated residue The components are ferric hydroxide and calcium fluoride, which are recycled as slagging agents in the ferronickel pyrometallurgy process. The specific steps include:

(1) Using hydrofluoric acid solution as the stripping agent, the P204 organic phase loaded with iron is mixed with the stripping agent for countercurrent stripping to obtain the iron ^- rich stripping solution and the blank P204 organic phase that entrains F-; The stripping rate of iron in the P204 organic phase of iron is 99.0%-99.5%.

(2) Use deionized water as the washing liquid to carry out countercurrent washing with the blank P204 organic phase entrained with F- ^, and obtain a blank P204 organic phase without F- after washing, ^and return the blank P204 organic phase without F- ^to the extraction system Recycling; the precipitation removal rate of iron and F ^- in the iron-rich stripping solution is 99.2% to 99.8%.

(3) Add lime slurry to the iron-rich stripping solution to neutralize precipitation and remove iron, react for 2-4 hours, and control the pH value at the end point at 3.5-5.5. The liquid phase obtained after filtration is an iron-poor solution, and the liquid phase is supplemented with hydrofluoric acid Return to the step (1) for recycling as a hydrofluoric acid solution, or return to the step (2) for recycling as a washing solution; the solid phase is iron removal slag containing ferric hydroxide and calcium fluoride.

The concentration of the hydrofluoric acid solution in the step (1) is 2-6 mol/L. The hydrofluoric acid solution is prepared by using industrial hydrofluoric acid with a weight content of HF·H2O ≥ 40%.

The content of ^Fe3+ in the P204 organic phase loaded with iron in the step (1) is 0.255˜2.0 g/L.

In the step (1), the volume ratio of the iron-loaded P204 organic phase to the stripping agent is 2-6:1.

In the step (1), the number of back-extraction stages of counter-current back-extraction is 1-4, and the back-extraction temperature is 25-40°C.

In the step (2), the volume ratio of the F ^- free blank P204 organic phase to the deionized water is 2-6:1.

The number of stages of countercurrent washing in the step (2) is 1-3, and the washing temperature is 25-35°C.

The lime slurry in the step (3) has a concentration of 10% to 20%, and is prepared from industrial lime with a CaO content of 80%.

The iron removal slag obtained in the step (3) is recycled as a slagging agent in the ferronickel pyrometallurgy process.

The present invention uses hydrofluoric acid to back-extract the Fe3 ⁺ -loaded P204 organic phase. The operating environment of the method is free from acid mist pollution. The extract is directly returned to the system for washing and stripping the P204 organic phase after stripping and iron removal, or continues to return to the stripping process for use after supplementing hydrofluoric acid. The components of the precipitated slag are ferric hydroxide and calcium fluoride, which are used as The slag-forming agent is recycled; the cost of the neutralizing precipitant is low, and it is easy to purchase and transport, which solves the problems in the traditional method of extracting Fe ³⁺ with hydrochloric acid. Because hydrochloric acid is a precursor drug, it is difficult to approve and supervise the purchase, and the cost High, difficult to deal with iron-rich hydrochloric acid stripping solution; the method of the present invention is more practical, simple in process, easy to operate and control, and achieves the effect of no waste residue and waste liquid discharge while reducing the cost of stripping, and is green and environmentally friendly. Zero emission, with the advantages of high efficiency, environmental protection and strong practicability.

Description of drawings

Fig. 1 is a schematic diagram of a process flow of the present invention;

Detailed ways

The present invention will be further described below in combination with the accompanying drawings and specific embodiments.

In the P204 organic phase loaded with Fe3 ⁺ in the embodiment of the present invention, the extractant P204 accounts for 10-30% of the total volume, and the diluent aviation kerosene accounts for 70-90% of the total volume.

In the embodiment of the present invention, the P204 extractant and the purchased diluent aviation kerosene mixed in the market are used to make the P204 organic phase, and the P204 organic phase is mixed and phase-separated with the aqueous solution of ferric sulfate to obtain the loaded Fe3 ⁺ P204 organic phase.

The hydrofluoric acid used in the embodiment of the present invention is commercially available industrial oxalic acid; the hydrofluoric acid solution is prepared by using industrial hydrofluoric acid with a weight content of HF·H ₂ O ≥ 40%.

The lime used in the embodiment of the present invention is a commercially available industrial lime product with a CaO content of 80%.

In the embodiment of the present invention, the mixing time for each stage of stripping is 5-10 minutes, and the clarification time is 5 minutes.

Comparative example:

Hydrochloric acid iron removal method: Measure 500ml of the above-mentioned P204 extractant loaded with Fe ³⁺ , prepare a 6mol/L hydrochloric acid solution, and then add it to the P204 extractant loaded with Fe ³⁺ according to the O/A ratio of 1:1. After mixing and stripping for 10 min, the lower aqueous phase solution was taken, and the content of Fe ³⁺ in the aqueous phase was measured by atomic absorption method, and the elution efficiency of Fe ³⁺ was obtained to be 97.0%-97.6%.

Example 1:

The volume of extractant P204 accounts for 10% in the P204 organic phase of loading iron, and the content of ^Fe is at 0.225g/L; The hydrofluoric acid solution that is 2mol/L is used as stripping agent with HF acid molar concentration, will load iron The P204 organic phase and the stripping agent are mixed at a volume ratio of O/A of 2:1 to carry out the first-stage stripping. The stripping time is 5 minutes, and the stripping temperature is 25°C. After the stripping is completed, an iron-rich stripping solution and a blank are obtained. P204 organic phase, the stripping rate of iron in the P204 organic phase loaded with iron is 99.0%; the iron-rich stripping liquid is removed by adding lime slurry to neutralize and precipitate iron and F ^- , and the reaction time is 2h; when adding lime slurry to reduce When removing iron and F ^- by precipitation, the pH value of the end point is controlled at 4; the material after iron removal by precipitation is filtered for liquid-solid separation; the precipitation removal rates of iron and F ^- in the iron-rich stripping solution are 99.2% and 99.6%, respectively. The liquid phase obtained by separation is an iron-poor solution, which can be recycled as a stripping agent after hydrofluoric acid supplementation, or directly returned to the organic phase after washing P204 stripping iron for recycling; the solid phase iron removal slag containing ferric hydroxide and Calcium fluoride is recycled as a slagging agent in the ferronickel pyrometallurgy process.

Example 2:

The volume of extractant P204 accounts for 20% in the P204 organic phase of loading iron, and the content of ^Fe is at 0.83g/L; The hydrofluoric acid solution that is 3mol/L with HF acid molar concentration is as stripping agent, will load iron The P204 organic phase and the stripping agent are mixed at a volume ratio of O/A of 3:1 to carry out reverse two-stage stripping. The stripping time is 5 minutes, and the stripping temperature is 30°C. After the stripping is completed, the iron-rich stripping solution and blank are obtained. P204 organic phase, the stripping rate of iron in the P204 organic phase loaded with iron is 99.3%; the iron-rich stripping liquid is removed by adding lime slurry to neutralize and precipitate iron and F ^- , and the reaction time is 3h; when adding lime slurry to reduce When removing iron and F ^- by precipitation, the final pH value is controlled at 4.5; the material after iron removal by precipitation is filtered for liquid-solid separation; the precipitation removal rates of iron and F ^- in the iron-rich stripping solution are 99.4% and 99.8%, respectively. The separated liquid phase is an iron-poor solution, which can be recycled as a stripping agent after hydrofluoric acid supplementation, or directly returned to the organic phase after washing P204 and stripping iron for recycling. The solid-phase iron removal slag containing ferric hydroxide and calcium fluoride is separated and recycled as a slagging agent in the ferronickel pyrometallurgy process;

Example 3:

The volume of extractant P204 accounts for 25% in the P204 organic phase of loading iron, and the content of ^Fe is at 1.35g/L; The hydrofluoric acid solution that is 4mol/L with HF acid molar concentration is used as stripping agent, will load iron The P204 organic phase and the stripping agent are mixed at a volume ratio of O/A of 4:1 for reverse 3-stage stripping. The stripping time is 8 minutes, and the stripping temperature is 35°C. After the stripping is completed, iron-rich stripping solution and blank are obtained. P204 organic phase, the stripping rate of iron in the P204 organic phase loaded with iron is 99.4%; the iron-rich stripping liquid is removed by adding lime slurry to neutralize and precipitate iron and F ^- , and the reaction time is 3h; when adding lime slurry to reduce When removing iron and F ^- by precipitation, the pH value of the end point is controlled at 5; the material after iron removal by precipitation is filtered for liquid-solid separation; the precipitation removal rates of iron and F ^- in the iron-rich stripping solution are 99.5% and 99.8%, respectively. The liquid phase obtained by separation is an iron-poor solution, which can be recycled as a stripping agent after hydrofluoric acid supplementation, or directly returned to the organic phase after washing P204 stripping iron for recycling; the solid phase iron removal slag containing ferric hydroxide and Calcium fluoride is recycled as a slagging agent in the ferronickel pyrometallurgy process.

Example 4:

The volume of extractant P204 accounts for 30% in the P204 organic phase of loading iron, and the content of ^Fe is at 1.96g/L; The hydrofluoric acid solution that is 6mol/L with HF acid molar concentration is as stripping agent, will load iron The P204 organic phase and the stripping agent are mixed at a volume ratio of O/A of 5:1 for reverse 4-stage stripping. The stripping time is 10 minutes, and the stripping temperature is 40°C. After the stripping is completed, iron-rich stripping solution and blank are obtained. P204 organic phase, the stripping rate of iron in the P204 organic phase loaded with iron is 99.5%; the iron-rich stripping liquid is removed by adding lime slurry to neutralize and precipitate iron and F ^- , and the reaction time is 4h; when adding lime slurry to reduce When removing iron and F- by precipitation ^, the final pH value is controlled at 5.5; the material after iron removal by precipitation is filtered for liquid-solid separation; the precipitation removal rates of iron and F- in the iron-rich stripping solution are 99.2% and 99.7%, respectively. The liquid phase obtained by separation is an iron-poor solution, which can be recycled as a stripping agent after hydrofluoric acid supplementation, or directly returned to the organic phase after washing P204 stripping iron for recycling; the solid phase iron removal slag containing ferric hydroxide and Calcium fluoride is recycled as a slagging agent in the ferronickel pyrometallurgy process.

Claims (9)

1. A kind of 1. Fe loaded in hydrofluoric acid back extraction P204 organic phases³⁺And the method for strip liquor processing, it is characterised in that specific step Suddenly include：

   (1) the P204 organic phases of load iron are mixed with back washing agent and carry out countercurrent reextraction as back washing agent using hydrofluoric acid solution Take, obtain rich iron strip liquor and entrainment F^-Blank P204 organic phases；

   (2) using deionized water as washing lotion and entrainment F^-Blank P204 organic phases carry out countercurrent washing, obtained after the completion of washing Without F^-Blank P204 organic phases, should F be free of^-Blank P204 organic phases return extracting system recycle；

   (3) lime slurry neutralization precipitation iron removaling is added into rich iron strip liquor, reacts 2~4h, endpoint pH control 3.5~ 5.5, the liquid phase obtained after filtering is poor ferrous solution, and the middle conduct hydrofluoric acid solution of return to step (1) follows after liquid phase supplements hydrofluoric acid Ring uses, or is recycled in return to step (2) as washing lotion；Solid phase is the iron dross removing containing iron hydroxide and calcirm-fluoride.
2. 2. the Fe loaded in hydrofluoric acid back extraction P204 organic phases according to claim 1³⁺And the method for strip liquor processing, its It is characterised by：The concentration of hydrofluoric acid solution is 2~6mol/L in the step (1).
3. 3. the Fe loaded in hydrofluoric acid back extraction P204 organic phases according to claim 1³⁺And the method for strip liquor processing, its It is characterised by：Fe in the P204 organic phases of load iron in the step (1)³⁺Content in 0.255~2.0g/L.
4. 4. the Fe loaded in hydrofluoric acid back extraction P204 organic phases according to claim 1³⁺And the method for strip liquor processing, its It is characterised by：The P204 organic phases of load iron and the volume ratio of back washing agent are 2~6 in the step (1)：1.
5. 5. the Fe loaded in the hydrofluoric acid back extraction P204 organic phases according to claim 1 or 4³⁺And the side of strip liquor processing Method, it is characterised in that：The back extraction series of countercurrent reextraction is 1~4 grade in the step (1), and back extraction temperature is 25~40 DEG C.
6. 6. the Fe loaded in hydrofluoric acid back extraction P204 organic phases according to claim 1³⁺And the method for strip liquor processing, its It is characterised by：The step (2) is free of F^-Blank P204 organic phases and deionized water volume ratio be 2~6：1.
7. 7. the Fe loaded in the hydrofluoric acid back extraction P204 organic phases according to claim 1 or 6³⁺And the side of strip liquor processing Method, it is characterised in that：The series of step (2) countercurrent washing is 1~3 grade, and wash temperature is 25~35 DEG C.
8. 8. the Fe loaded in hydrofluoric acid back extraction P204 organic phases according to claim 1³⁺And the method for strip liquor processing, its It is characterised by：The concentration of lime slurry is 10%~20% in the step (3).
9. 9. the Fe loaded in hydrofluoric acid back extraction P204 organic phases according to claim 1³⁺And the method for strip liquor processing, its It is characterised by：The iron dross removing obtained in the step (3) is recycled as the slag former during ferronickel pyrometallurgical smelting.