A method for removing fluorine and chlorine by using ultrasound to strengthen polysulfate

Abstract

The present invention relates to a new method for removing fluorine and chlorine by ultrasonic enhancement of polysulfate, belonging to the field of purification technology. In the present invention, the solution after germanium precipitation is heated to a preset temperature I, a neutralizing agent is added for two neutralizations until the pH value is 5.2 - 5.5, and an inorganic polymer flocculant is added during the second neutralization, and short-term ultrasonic is added to efficiently remove fluorine and chlorine. After solid-liquid separation, fluorine-chlorine-iron slag and neutralized solution are obtained; the fluorine-chlorine-iron slag is subjected to evaporation and stripping, and fluorine and chlorine are absorbed by slaked lime, so that they are recycled and opened in the form of calcium fluoride and calcium chloride products, and the residual iron slag is returned to neutralization.

Description

Technical Field

[0001] The invention relates to the technical field of purification, and in particular to a method for removing fluorine and chlorine by using ultrasonic enhanced polysulfate. Background Art

[0002] The fluorine and chlorine content of the solution after tannin germanium precipitation is high. When the concentration of fluorine ions in the solution exceeds 50 mg / L during electrolysis, the cathode aluminum plate begins to thin, making it difficult to strip the plate, which will seriously affect production. When the chloride ion concentration exceeds 100 mg / L, the zinc grade rate caused by corrosion products decreases, seriously deteriorating the operating environment. The content of chloride ions in the electrolyte is generally controlled within 100~200 mg / L.

[0003] At present, the methods for removing fluorine and chlorine from solutions mainly include goethite method, adsorption method, extraction method and volatilization method. 3+ Produce FeOOH (goethite) and avoid colloidal Fe(OH) 3 Generation. The goethite method can adsorb any anion, has a high removal rate for anionic impurities, and can remove certain cationic impurities, but the operation requirements are high. The adsorption method is mainly used to prepare hydrotalcite-like compounds, that is, a layered dihydroxy composite metal oxide that absorbs anions, but the cost of use is high and the removal rate of fluorine and chlorine is low. The extraction method uses trialkyl tertiary amines, n-octanol and 260# sulfonated kerosene as organic phases to extract fluorine and chlorine. The raffinate is sent for electrolysis after adsorption on activated carbon, but the process is easy to emulsify and is not suitable for application in the main system. The volatilization method is based on the volatile properties of hydrofluoric acid and hydrochloric acid, and directly heats and stirs with air, but the evaporation cost is high and it is not suitable for direct treatment of the solution. Summary of the invention

[0004] The present invention aims at the shortcomings of the prior art such as low fluorine and chlorine removal rate, high cost and complex process, and proposes a method for removing fluorine and chlorine by using ultrasonic enhanced polysulfate. The present invention adds a polymer flocculant and briefly ultrasonically enhances the adsorption of fluorine and chlorine in the neutralization stage to obtain fluorine-chlorine iron slag, which evaporates and is absorbed by slaked lime liquid to generate calcium chloride and calcium fluoride, which are separated from the system. After the fluorine and chlorine are removed, the iron slag is directly returned to the neutralization stage. The present invention ensures the stability of the electrolysis system while recycling solid waste, and has low fluorine and chlorine removal cost and high efficiency.

[0005] The present invention provides a method for removing fluorine and chlorine by using ultrasonic enhanced polysulfate, comprising the following steps:

[0006] (1) Removal of fluorine and chlorine in the neutralization stage: The liquid after germanium precipitation is heated to a preset temperature I, and a neutralizer is added to neutralize twice until the pH value is 5.2-5.5. An inorganic polymer flocculant is added during the second neutralization, and a short ultrasound is added to efficiently remove fluorine and chlorine. The solid-liquid separation obtains fluorine-chlorine iron slag and neutralized liquid;

[0007] The neutralizing agent is a zinc roasted sand mixture, wherein the iron content of the zinc roasted sand is 2-12wt.%, the zinc content is 30-65wt.%, and the zinc oxide accounts for 65-85wt.%;

[0008] The polysulfate inorganic polymer flocculant is polyferric sulfate, and the added amount is 0.5 to 5 times the mass of fluorine and chlorine;

[0009] The short ultrasound is 10-20 minutes of ultrasound, the ultrasound frequency is 20kHz, and the ultrasound intensity is 0.4-1w / cm 2 .

[0010] (2) Fluorine and chlorine separation: The fluorine and chlorine iron slag is evaporated and blown off, and the fluorine and chlorine are absorbed by slaked lime and recovered in the form of calcium fluoride and calcium chloride products. The residual iron slag is returned for neutralization.

[0011] Furthermore, after the germanium is precipitated in step (1), the liquid has a fluorine content of 60-200 mg / L, a chlorine content of 60-200 mg / L, a total iron content of 1-8 g / L, a pH of 2-3, and a temperature of 50-60°C.

[0012] Furthermore, the preset temperature of step (1) is 80-90°C, and the total amount of the roasted sand mixture added is 73.7-2087 g / m 3 ; During the first neutralization, the amount of the roasted sand mixture added is 20~30% of the theoretical amount, and the neutralization time is 0.5~1h; during the second neutralization, the amount of the roasted sand mixture added is 70~80% of the theoretical amount, and the neutralization time is 1~2h.

[0013] Furthermore, in step (2), the moisture content of the fluorine-chlorine iron slag is 40-60%, the stripping temperature is 120-180°C, the pressure is -0.5-0.1 kPa, and the air flow rate is 300-800 m³ / h.

[0014] Furthermore, in step (2), the concentration of the slaked lime absorption solution is 20-60 g / L, and the absorption volume is 20%-50% of the volume of the fluorinated ferrochloric acid slag.

[0015] It is to be understood that the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the present invention.

[0016] Beneficial technical effects of the present invention:

[0017] (1) The present invention removes fluorine and chlorine by neutralizing electrostatic adsorption in the first stage and precipitating fluorine and chlorine adsorbents by high molecular weight flocculants in the second stage, thereby achieving deep removal of fluorine and chlorine;

[0018] (2) The ultrasonic energy of the present invention can significantly improve the utilization efficiency of high molecular polymers;

[0019] (3) The present invention achieves complete separation of fluorine and chlorine from the system while efficiently utilizing valuable elements by evaporating and blowing off fluorine and chlorine iron slag, separating salt from lime, and recycling iron slag;

[0020] (3) The present invention has a simple process, short processing time, clean and environmentally friendly process, low energy consumption, and has great environmental and economic benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 The present invention is a process flow chart of an embodiment of the present invention. DETAILED DESCRIPTION

[0022] The optional embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. Although the optional embodiments of the present invention are shown in the accompanying drawings, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments described herein. On the contrary, these embodiments are provided to make the present invention more thorough and complete, and to fully convey the scope of the present invention to those skilled in the art.

[0023] The terms used in this application are only for the purpose of describing specific embodiments and are not intended to limit this application. The singular forms of "a", "said" and "the" used in this application and the appended claims are also intended to include plural forms unless the context clearly indicates other meanings. It should also be understood that the term "and / or" used herein refers to and includes any or all possible combinations of one or more associated listed items.

[0024] The following is a detailed description of the method for removing fluorine and chlorine by using ultrasonic enhanced polysulfate in the present invention in conjunction with the accompanying drawings, as follows:

[0025] (1) Removal of fluorine and chlorine in the neutralization stage: The liquid after germanium precipitation is heated to a preset temperature I, and a neutralizer is added to neutralize twice until the pH value is 5.2-5.5. During the second neutralization, polyferric sulfate inorganic polymer flocculant is added, and a short ultrasound is added to efficiently remove fluorine and chlorine. The solid-liquid separation obtains fluorine-chlorine iron slag and neutralized liquid;

[0026] The neutralizing agent is a mixture of zinc roasted sand, wherein the iron content of the zinc roasted sand is 2-12wt.%, the zinc content is 30-65wt.%, and the zinc oxide accounts for 65-85wt.%;

[0027] The polysulfate inorganic polymer flocculant is polyferric sulfate, and the added amount is 0.5~5 times the mass of fluorine and chlorine. When the flocculant is added, ultrasonic waves are added for 10~20 minutes. The ultrasonic frequency is 20kHz and the ultrasonic intensity is 0.4~1w / cm 2 .

[0028] (2) Fluorine and chlorine separation: The fluorine and chlorine iron slag is evaporated and blown off, and the fluorine and chlorine are absorbed by slaked lime and recovered in the form of calcium fluoride and calcium chloride products. The residual iron slag is returned for neutralization.

[0029] The iron hydroxide colloid generated in the neutralization stage of the present invention is a cationic colloid, which has a good electrostatic attraction effect on F and Cl in the solution. The high molecular polymer is a multi-metal compound with a FeOOH structure, has a layered structure, and has a large molecular weight. After strengthening the electrostatics, F and Cl are adsorbed and precipitated. When adding the high molecular polymer, adding fast high-intensity ultrasound can avoid the self-wrapping loss of the polymer, strengthen the dispersion of the polymer, strengthen the collision with the colloid adsorbed F and Cl, and improve the polymer reaction efficiency.

[0030] In one embodiment of the present invention, after germanium precipitation in step (1), the liquid F content is 60-200 mg / L, the Cl content is 60-200 mg / L, the total iron content is 1-8 g / L, the pH is 2-3, and the temperature is 50-60°C.

[0031] In one embodiment of the present invention, the preset temperature of step (1) is 80-90°C, and the total amount of the roasted sand mixture added is 73.7-2087 g / m 3 ; During the first neutralization, the amount of the roasted sand mixture added is 20-30% of the theoretical amount, and the neutralization time is 0.5-1h; during the second neutralization, the amount of the roasted sand mixture added is 70-80% of the theoretical amount, and the neutralization time is 1-2h.

[0032] In one embodiment of the present invention, the moisture content of the fluorine-chlorine iron slag in step (2) is 40-60%, the stripping temperature is 120-180°C, the pressure is -0.5-0.1 kPa, and the air flow rate is 300-800 m³ / h.

[0033] In one embodiment of the present invention, the concentration of the slaked lime absorption solution in step (2) is 20-60 g / L, and the absorption volume is 20%-50% of the volume of the fluorinated iron slag.

[0034] For the purpose of greater clarity, the invention is described in detail through the following embodiments.

[0035] Example 1: A method for removing fluorine and chlorine by using ultrasonic enhanced polysulfate (see Figure 1 ), the specific steps are as follows:

[0036] (1) Neutralization stage: Remove fluorine and chlorine: Heat the germanium precipitation solution (F content of 60 mg / L, Cl content of 60 mg / L, total iron content of 1 g / L, pH of 2, temperature of 50°C) to the preset temperature of 80°C, add the roasted sand mixture and neutralize twice to a pH value of 5.2. The roasted sand is a mixture of roasted sand and iron slag. The iron content of the mixture is 2wt.%, the zinc content is 30wt.%, and the zinc oxide accounts for 65wt.%. The total amount of roasted sand mixture added is 73.7g / m 3 The amount of the roasted sand mixture added in the first neutralization was 20% of the theoretical amount, and the neutralization time was 0.5h. The amount of the roasted sand mixture added in the second neutralization was 80% of the theoretical amount, and the neutralization time was 1h. In the second neutralization, polyferric sulfate inorganic polymer flocculant was added, and the added amount was 0.5 times the mass of fluorine and chlorine. When the flocculant was added, ultrasonic waves were added for 10 minutes, the ultrasonic frequency was 20kHz, and the ultrasonic intensity was 0.4w / cm 2 . Solid-liquid separation to obtain fluorine-chlorine-iron slag and neutralized liquid;

[0037] (2) Fluorine and chlorine salt separation: The fluorine and chlorine iron slag with a moisture content of 40% is evaporated and blown off at a temperature of 120°C, a pressure of -0.5kPa, and an air flow rate of 300m³ / h. After evaporation, the iron slag is returned for neutralization. The evaporated gas uses 20g / L slaked lime to absorb fluorine and chlorine, and the absorption volume is 20% of the volume of the fluorine and chlorine iron slag. After a period of time, the absorption liquid is separated into liquid and solid, and the obtained calcium chloride and calcium fluoride are directly sold for external treatment.

[0038] In this embodiment, the fluorine and chlorine content of the neutralizing liquid is reduced to 10 mg / L.

[0039] Example 2: A method for removing fluorine and chlorine by using ultrasonic enhanced polysulfate (see Figure 1 ), the specific steps are as follows:

[0040] (1) Neutralization stage to remove fluorine and chlorine: Heat the germanium precipitation solution (F content of 120 mg / L, Cl content of 120 mg / L, total iron content of 4 g / L, pH of 2-32.5, temperature of 55°C) to the preset temperature of 85°C, add the roasted sand mixture to neutralize twice to a pH of 5.3. The roasted sand is a mixture of roasted sand and iron slag. The iron content of the mixture is 6 wt.%, and the zinc content is 45 wt.%, of which zinc oxide accounts for 70 wt.%. The total amount of roasted sand mixture added is 1042 g / m 3 The amount of the roasted sand mixture added in the first neutralization was 25% of the theoretical amount, and the neutralization time was 45 minutes. The amount of the roasted sand mixture added in the second neutralization was 75% of the theoretical amount, and the neutralization time was 1.5 hours. In the second neutralization, polyferric sulfate inorganic polymer flocculant was added, and the amount added was twice the mass of fluorine and chlorine. When the flocculant was added, ultrasonic waves were added for 15 minutes, the ultrasonic frequency was 20kHz, and the ultrasonic intensity was 0.6w / cm2 . Solid-liquid separation to obtain fluorine-chlorine-iron slag and neutralized liquid;

[0041] (2) Fluorine and chlorine salt separation: The fluorine and chlorine iron slag with a moisture content of 50% is evaporated and blown off at a temperature of 150°C, a pressure of -0.3kPa, and an air flow rate of 500m³ / h. After evaporation, the iron slag is returned for neutralization. The evaporated gas uses 40g / L slaked lime to absorb fluorine and chlorine, and the absorption volume is 30% of the volume of the fluorine and chlorine iron slag. After a period of time, the absorption liquid is separated into liquid and solid, and the obtained calcium chloride and calcium fluoride are directly sold for external treatment.

[0042] In this embodiment, the fluorine and chlorine content of the neutralizing liquid is reduced to 30 mg / L.

[0043] Example 3: A method for removing fluorine and chlorine by using ultrasonic enhanced polysulfate (see Figure 1 ), the specific steps are as follows:

[0044] (1) Neutralization stage to remove fluorine and chlorine: The solution after germanium precipitation (F content of 200 mg / L, Cl content of 200 mg / L, total iron content of 8 g / L, pH of 3, temperature of 60°C) was heated to a preset temperature of 90°C, and the roasted sand mixture was added to neutralize twice until the pH value was 5.5. The roasted sand was a mixture of roasted sand and iron slag, and the iron content in the mixture was 12wt.%, and the zinc content was 65wt.%, of which zinc oxide accounted for 85wt.%. The total amount of roasted sand mixture added was 2087g / m 3 The amount of the roasted sand mixture added in the first neutralization was 30% of the theoretical amount, and the neutralization time was 1 hour. The amount of the roasted sand mixture added in the second neutralization was 80% of the theoretical amount, and the neutralization time was 2 hours. In the second neutralization, polyferric sulfate inorganic polymer flocculant was added, and the amount added was 5 times the mass of fluorine and chlorine. When the flocculant was added, ultrasonic waves were added for 20 minutes, the ultrasonic frequency was 20kHz, and the ultrasonic intensity was 1w / cm 2 . Solid-liquid separation to obtain fluorine-chlorine-iron slag and neutralized liquid;

[0045] (2) Fluorine and chlorine salt separation: The fluorine and chlorine iron slag with a moisture content of 60% is evaporated and blown off at a temperature of 180°C, a pressure of -0.1kPa, and an air flow rate of 800m³ / h. After evaporation, the iron slag is returned for neutralization. The evaporated gas uses 60g / L slaked lime to absorb fluorine and chlorine, and the absorption volume is 50% of the volume of the fluorine and chlorine iron slag. After a period of time, the absorption liquid is separated into liquid and solid, and the obtained calcium chloride and calcium fluoride are directly sold for external treatment.

[0046] In this embodiment, the fluorine and chlorine content of the neutralizing liquid is reduced to 25 mg / L.

[0047] The embodiments of the present invention have been described above, and the above description is exemplary, not exhaustive, and is not limited to the disclosed embodiments. Many modifications and changes will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the described embodiments. The selection of terms used herein is intended to best explain the principles of the embodiments, practical applications, or improvements to the technology in the market, or to enable other persons of ordinary skill in the art to understand the embodiments disclosed herein.

Claims

1. A method for removing fluorine and chlorine by ultrasonic-enhanced polysulfate, characterized in that, the specific steps are as follows: (1) Removing fluorine and chlorine in the neutralization stage: After the germanium precipitation solution is heated to the preset temperature I, a neutralizing agent is added for two neutralizations until the pH value is 5.2 - 5.

5. During the second neutralization, a polysulfate inorganic polymer flocculant is added, and short-term ultrasonic is applied to efficiently remove fluorine and chlorine. After solid-liquid separation, fluorine-chlorine-iron slag and neutralized solution are obtained; The neutralizing agent is a zinc calcine mixture, with the iron content in the zinc calcine being 2 - 12 wt.%, the zinc content being 30 - 65 wt.%, and the proportion of zinc oxide being 65 - 85 wt.%; The polysulfate inorganic polymer flocculant is polyferric sulfate, and the addition amount is 0.5 - 5 times the mass of fluorine and chlorine; The transient ultrasound is 10 - 20 min of ultrasonic waves with a frequency of 20 kHz and an intensity of 0.4 - 1 W / cm 2 ; (2) Fluorine-chlorine salt separation: The fluorine-chlorine-iron slag is subjected to evaporation and stripping, and fluorine and chlorine are absorbed by slaked lime, so that they are recycled and discharged in the form of calcium fluoride and calcium chloride products, and the residual iron slag is returned to neutralization.

2. The method for removing fluorine and chlorine by ultrasonic-enhanced polysulfate according to claim 1, characterized in that: In step (1), the fluorine content in the germanium precipitation solution is 60 - 200 mg / L, the chlorine content is 60 - 200 mg / L, the total iron content is 1 - 8 g / L, the pH is 2 - 3, and the temperature is 50 - 60 °C.

3. The method for removing fluorine and chlorine by ultrasonic-enhanced polysulfate according to claim 1, characterized in that: Step (1): Preset the temperature at 80 - 90°C, and the total addition amount of the calcine mixture is 73.7 - 2087 g / m 3 ; During the first neutralization, the addition amount of the calcine mixture is 20 - 30% of the theoretical amount, and the neutralization time is 0.5 - 1 h; during the second neutralization, the addition amount of the calcine mixture is 70 - 80% of the theoretical amount, and the neutralization time is 1 - 2 h.

4. The method for removing fluorine and chlorine by ultrasonic-enhanced polysulfate according to claim 1, characterized in that: In step (2), the water content of the fluorine-chlorine-iron slag is 40 - 60%, the stripping temperature is 120 - 180 °C, the pressure is -0.5 - -0.1 kPa, and the air flow rate is 300 - 800 m³ / h.

5. The method for removing fluorine and chlorine by ultrasonic-enhanced polysulfate according to claim 1, characterized in that: In step (2), the concentration of the slaked lime absorption solution is 20 - 60 g / L, and the absorption volume is 20% - 50% of the volume of the fluorine-chlorine-iron slag.

Images