Method for degrading and separating organic matters on surface of bauxite

Abstract

The invention relates to a method for degrading and separating organic matters on the surface of bauxite, and belongs to the technical field of mineral processing. The method comprises the following steps: uniformly mixing bauxite and a NaOH solution, carrying out ultrasonic enhanced leaching for 40-80 minutes at the temperature of 80-99 DEG C to obtain leached slurry, and carrying out solid-liquid separation to obtain bauxite without organic matters and alkaline leachate containing the organic matters; the method comprises the following steps: adding a nano Mn-coated TiO2 photocatalyst into an alkaline leaching solution containing organic matters, carrying out photocatalytic reaction under illumination and ultrasonic conditions to degrade the organic matters into CO2 and water, and absorbing CO2 to generate Na2CO3, thereby obtaining an alkaline solution containing Na2CO3; lime water is added into alkaline liquid containing Na2CO3, so that Na2CO3 is converted into CaCO3 sediment and NaOH, NaOH solution regeneration liquid is obtained through solid-liquid separation, and the NaOH solution regeneration liquid can be directly used for ultrasonic enhanced leaching of the next batch of bauxite. The method directly separates the organic matters from the bauxite, prevents the organic matters from entering the Bayer process, is thorough in organic matter separation and high in efficiency, does not generate any waste, and is low in economic cost.

Description

Technical Field

[0001] The invention relates to a method for degrading and separating organic matter on the surface of bauxite, belonging to the technical field of mineral processing. Background Art

[0002] At present, the Bayer process using bauxite as raw material is still the best choice for industrial production of alumina. However, bauxite naturally contains organic matter of several ten-thousandths to several thousandths. During the dissolution stage, these organic matter will enter the Bayer liquor. As the mother liquor is recycled, the organic matter will continue to accumulate, which will eventually increase the viscosity, specific gravity and specific heat of the mother liquor, hinder the sedimentation of red mud; hinder the contact between alkali liquid and bauxite, reduce the dissolution rate of alumina; reduce the decomposition rate of seed crystals; reduce the particle size of aluminum hydroxide, and fail to obtain qualified alumina products; accelerate the scarring rate of equipment and reduce the service life of equipment.

[0003] At present, the methods for removing organic matter in the Bayer process are mainly concentrated after the bauxite is dissolved. Removing organic matter from the Bayer process has the problems of high energy consumption, complex equipment and process, and incomplete removal. Summary of the invention

[0004] In view of the problems of high energy consumption, complex equipment and process, and incomplete removal in the prior art of removing organic matter from the Bayer process, the present invention proposes a method for degrading and separating organic matter on the surface of bauxite, which removes organic matter in bauxite from the production source and purifies the leachate, directly solving the problem of organic matter entering the Bayer process.

[0005] A method for degrading and separating organic matter on the surface of bauxite, the specific steps are as follows:

[0006] (1) mixing bauxite and NaOH solution uniformly, leaching by ultrasonic enhancement for 40 to 80 minutes at a temperature of 80 to 99° C. to obtain a leaching slurry, and performing solid-liquid separation to obtain bauxite free of organic matter and an alkaline leaching solution containing organic matter;

[0007] (2) adding nano-Mn@TiO2 photocatalyst to an alkaline leaching solution containing organic matter, and performing a photocatalytic reaction under light and ultrasound conditions to degrade the organic matter into CO2 and water, wherein CO2 is absorbed to generate Na2CO3 to obtain an alkaline solution containing Na2CO3;

[0008] (3) Add lime water to the alkaline solution containing Na2CO3 to convert Na2CO3 into CaCO3 precipitate and NaOH to simultaneously achieve CO3 2- The NaOH solution is removed and supplemented, and the solid-liquid separation is performed to obtain a NaOH solution regeneration liquid; the NaOH solution regeneration liquid is returned to step (1) to replace the NaOH solution.

[0009] Preferably, in step (1), the solid-to-liquid ratio of bauxite to NaOH solution is 1 to 5:10 in g:mL, the concentration of NaOH is 200 to 300 g / L, the ultrasonic power is 110 to 660 W, and the frequency is 40 kHz.

[0010] Preferably, in step (2), the solid-to-liquid ratio of the nano-Mn@TiO2 photocatalyst to the alkaline leaching solution containing organic matter is 0.4 to 3:100.

[0011] Preferably, the irradiation power in step (2) is 2-8 kW, the emission wavelength is 365.0 nm; the ultrasonic power is 110-660 W, and the frequency is 40 kHz.

[0012] Preferably, the method for preparing the nano-Mn@TiO2 photocatalyst in step (2) comprises the following specific steps:

[0013] 1) dissolving tetrabutyl titanate in anhydrous ethanol to obtain a tetrabutyl titanate solution;

[0014] 2) adding manganese acetate to tetrabutyl titanate solution and performing ultrasonic dispersion to obtain a slurry;

[0015] 3) The slurry is woven into a fiber membrane by electrospinning, and the fiber membrane is calcined at a temperature of 400-1000° C. in an argon atmosphere for 60-120 min to obtain a highly active nano-Mn@TiO2 photocatalyst.

[0016] More preferably, in step 1), the volume ratio of tetrabutyl titanate to anhydrous ethanol is 1 to 4:6.

[0017] More preferably, the ultrasonic power in step 2) is 110-660 W, the frequency is 40 kHz, and the solid-liquid ratio of manganese acetate to tetrabutyl titanate solution is 0.5-1.4:4 g:mL.

[0018] Preferably, the concentration of lime water in step (3) is 6 to 15 g / L, and the volume ratio of lime water to the alkaline liquid containing Na2CO3 is 1 to 6:5.

[0019] The beneficial effects of the present invention are:

[0020] (1) The present invention completely and efficiently separates organic matter from the production source of the Bayer process, directly solving the problem of organic matter entering the Bayer process;

[0021] (2) The entire process of the present invention is carried out under the condition of ultrasonic enhancement, which greatly shortens the reaction time and improves the production efficiency;

[0022] (3) All organic matter in the present invention is converted into CO2 and finally into CaCO3, thereby achieving the capture and fixation of CO2;

[0023] (4) The whole process of the present invention is carried out at low temperature and normal pressure, with low economic cost and energy consumption, high efficiency, strong operability, and no "three wastes" are generated, so it is clean and pollution-free. DETAILED DESCRIPTION

[0024] The present invention is further described in detail below in conjunction with specific implementation modes, but the protection scope of the present invention is not limited to the described contents.

[0025] Embodiment 1: The preparation method of the nano Mn@TiO2 photocatalyst of this embodiment comprises the following specific steps:

[0026] 1) dissolving tetrabutyl titanate in anhydrous ethanol to obtain a tetrabutyl titanate solution; the volume ratio of tetrabutyl titanate to anhydrous ethanol is 1:6;

[0027] 2) adding manganese acetate to tetrabutyl titanate solution and ultrasonically dispersing to obtain a slurry; the solid-liquid ratio of manganese acetate to tetrabutyl titanate solution is 0.5:4 g:mL, the ultrasonic power is 110 W, and the frequency is 40 kHz;

[0028] 3) The slurry was woven into a fiber membrane by electrospinning, and the fiber membrane was calcined at 400°C in an argon atmosphere for 60 minutes to obtain a highly active nano-Mn@TiO2 photocatalyst;

[0029] A method for degrading and separating organic matter on the surface of bauxite, the specific steps are as follows:

[0030] (1) The bauxite and the NaOH solution are mixed uniformly, and ultrasonic enhanced leaching is performed at a temperature of 80° C. for 40 minutes to obtain a leaching slurry, and solid-liquid separation is performed to obtain bauxite with low organic matter content and an alkaline leaching solution containing organic matter; the solid-liquid ratio of the bauxite and the NaOH solution is g:mL 1:10, the concentration of NaOH is 200 g / L, the ultrasonic power is 110 W, and the frequency is 40 kHz;

[0031] (2) adding nano-Mn@TiO2 photocatalyst to an alkaline leaching solution containing organic matter, performing a photocatalytic reaction under light and ultrasound conditions, degrading the organic matter into CO2 and water, wherein CO2 is absorbed to generate Na2CO3 to obtain an alkaline solution containing Na2CO3; the solid-liquid ratio g:mL of the nano-Mn@TiO2 photocatalyst to the alkaline leaching solution containing organic matter is 0.4:100; the power of the light is 2kW, the emission wavelength is 365.0nm; the ultrasonic power is 110W, and the frequency is 40kHz;

[0032] (3) Add lime water with a concentration of 6 g / L into the alkaline solution containing Na2CO3 to convert Na2CO3 into CaCO3 precipitate and NaOH to simultaneously achieve CO3 2-The NaOH solution is removed and supplemented, and the solid-liquid separation is performed to obtain a NaOH solution regeneration liquid; the NaOH solution regeneration liquid is returned to step (1) to replace the NaOH solution; the volume ratio of the lime water to the alkaline liquid containing Na2CO3 is 1:5;

[0033] After testing, 86.32% of the organic carbon in the bauxite was separated, and the total organic carbon removal rate in the alkaline leaching solution containing organic matter was 85.63%, of which the sodium humate removal rate was 89.32% and the sodium oxalate removal rate was 78.69%; the Na2CO3 concentration in the final NaOH solution regeneration liquid was less than 0.01g / L.

[0034] Embodiment 2: The preparation method of the nano Mn@TiO2 photocatalyst of this embodiment comprises the following specific steps:

[0035] 1) dissolving tetrabutyl titanate in anhydrous ethanol to obtain a tetrabutyl titanate solution; the volume ratio of tetrabutyl titanate to anhydrous ethanol is 2.5:6;

[0036] 2) adding manganese acetate to tetrabutyl titanate solution and ultrasonically dispersing to obtain a slurry; the solid-liquid ratio of manganese acetate to tetrabutyl titanate solution is 1:4, the ultrasonic power is 550 W, and the frequency is 40 kHz;

[0037] 3) The slurry was woven into a fiber membrane by electrospinning, and the fiber membrane was calcined at 800°C in an argon atmosphere for 80 minutes to obtain a highly active nano-Mn@TiO2 photocatalyst;

[0038] A method for degrading and separating organic matter on the surface of bauxite, the specific steps are as follows:

[0039] (1) The bauxite and the NaOH solution were mixed evenly, and ultrasonic enhanced leaching was performed at a temperature of 95°C for 70 minutes to obtain a leaching slurry, and solid-liquid separation was performed to obtain bauxite with low organic matter content and an alkaline leaching solution containing organic matter; the solid-liquid ratio of the bauxite and the NaOH solution was 3:10 in g:mL, the concentration of NaOH was 260 g / L, the ultrasonic power was 550 W, and the frequency was 40 kHz;

[0040] (2) adding nano-Mn@TiO2 photocatalyst to an alkaline leaching solution containing organic matter, performing a photocatalytic reaction under light and ultrasound conditions, degrading the organic matter into CO2 and water, wherein CO2 is absorbed to generate Na2CO3 to obtain an alkaline solution containing Na2CO3; the solid-liquid ratio of the nano-Mn@TiO2 photocatalyst to the alkaline leaching solution containing organic matter is 2.5:100 g:mL; the light power is 6kW, the emission wavelength is 365.0nm; the ultrasound power is 550W, and the frequency is 40kHz;

[0041] (3) Add lime water with a concentration of 8 g / L into the alkaline solution containing Na2CO3 to convert Na2CO3 into CaCO3 precipitate and NaOH to simultaneously achieve CO3 2- The NaOH solution is removed and supplemented, and the solid-liquid separation is performed to obtain a NaOH solution regeneration liquid; the NaOH solution regeneration liquid is returned to step (1) to replace the NaOH solution; the volume ratio of the lime water to the alkaline liquid containing Na2CO3 is 2:5;

[0042] After testing, 92.35% of the organic carbon in the bauxite was separated, and the total organic carbon removal rate in the alkaline leaching solution containing organic matter was 99.96%, of which the sodium humate removal rate was 100% and the sodium oxalate removal rate was 99.99%; there was no Na2CO3 in the final NaOH solution regeneration liquid.

[0043] Embodiment 3: The preparation method of the nano Mn@TiO2 photocatalyst of this embodiment comprises the following specific steps:

[0044] 1) dissolving tetrabutyl titanate in anhydrous ethanol to obtain a tetrabutyl titanate solution; the volume ratio of tetrabutyl titanate to anhydrous ethanol is 4:6;

[0045] 2) adding manganese acetate to tetrabutyl titanate solution and ultrasonically dispersing to obtain a slurry; the solid-liquid ratio of manganese acetate to tetrabutyl titanate solution is 1.4:4 g:mL, the ultrasonic power is 660 W, and the frequency is 40 kHz;

[0046] 3) The slurry was woven into a fiber membrane by electrospinning, and the fiber membrane was calcined at 1000°C in an argon atmosphere for 120 min to obtain a highly active nano-Mn@TiO2 photocatalyst;

[0047] A method for degrading and separating organic matter on the surface of bauxite, the specific steps are as follows:

[0048] (1) The bauxite and the NaOH solution were mixed evenly, and ultrasonic enhanced leaching was performed at a temperature of 99° C. for 80 min to obtain a leaching slurry, and solid-liquid separation was performed to obtain bauxite with low organic matter content and an alkaline leaching solution containing organic matter; the solid-liquid ratio of the bauxite and the NaOH solution was 5:10 g:mL, the concentration of NaOH was 300 g / L, the ultrasonic power was 660 W, and the frequency was 40 kHz;

[0049] (2) adding nano-Mn@TiO2 photocatalyst to an alkaline leaching solution containing organic matter, performing a photocatalytic reaction under light and ultrasound conditions, degrading the organic matter into CO2 and water, wherein CO2 is absorbed to generate Na2CO3 to obtain an alkaline solution containing Na2CO3; the solid-liquid ratio of the nano-Mn@TiO2 photocatalyst to the alkaline leaching solution containing organic matter is 3:100 g:mL; the light power is 8kW, the emission wavelength is 365.0nm; the ultrasound power is 660W, and the frequency is 40kHz;

[0050] (3) Add lime water with a concentration of 15 g / L into the alkaline solution containing Na2CO3 to convert Na2CO3 into CaCO3 precipitate and NaOH to simultaneously achieve CO3 2- The NaOH solution is removed and supplemented, and the solid-liquid separation is performed to obtain a NaOH solution regeneration liquid; the NaOH solution regeneration liquid is returned to step (1) to replace the NaOH solution; the volume ratio of the lime water to the alkaline liquid containing Na2CO3 is 6:5;

[0051] After testing, 88.82% of the organic carbon in the bauxite was separated, and the total organic carbon removal rate in the alkaline leaching solution containing organic matter was 93.27%, of which the removal rate of sodium humate was 95.63% and the removal rate of sodium oxalate was 85.92%; there was no Na2CO3 in the final NaOH solution regeneration liquid.

[0052] The specific implementation modes of the present invention are described in detail above, but the present invention is not limited to the above implementation modes, and various changes can be made within the knowledge scope of ordinary technicians in this field without departing from the purpose of the present invention.

Claims

1. A method for degrading and separating organic matter on the surface of bauxite, characterized in that: The specific steps are as follows: (1) mixing bauxite and NaOH solution uniformly, leaching by ultrasonic enhancement for 40 to 80 minutes at a temperature of 80 to 99° C. to obtain a leaching slurry, and performing solid-liquid separation to obtain bauxite free of organic matter and an alkaline leaching solution containing organic matter; (2) adding nano-Mn@TiO2 photocatalyst to an alkaline leaching solution containing organic matter, and performing a photocatalytic reaction under light and ultrasound conditions to degrade the organic matter into CO2 and water, wherein CO2 is absorbed to generate Na2CO3 to obtain an alkaline solution containing Na2CO3; (3) adding lime water to the alkaline solution containing Na2CO3 to convert Na2CO3 into CaCO3 precipitate and NaOH, and separating the solid and liquid to obtain NaOH solution regeneration liquid; the NaOH solution regeneration liquid is returned to step (1) to replace the NaOH solution.

2. The method for degrading and separating organic matter on the surface of bauxite according to claim 1, characterized in that: In step (1), the solid-liquid ratio of bauxite to NaOH solution is 1 to 5:10 in g:mL, the concentration of NaOH is 200 to 300 g / L, the ultrasonic power is 110 to 660 W, and the frequency is 40 kHz.

3. The method for degrading and separating organic matter on the surface of bauxite according to claim 1, characterized in that: In step (2), the solid-liquid ratio of the nano-Mn@TiO2 photocatalyst to the alkaline leaching solution containing organic matter is 0.4 to 3:

100.

4. The method for degrading and separating organic matter on the surface of bauxite according to claim 1 or 3, characterized in that: In step (2), the power of the illumination is 2-8 kW, and the emission wavelength is 365.0 nm; the power of the ultrasound is 110-660 W, and the frequency is 40 kHz.

5. The method for degrading and separating organic matter on the surface of bauxite according to claim 1, characterized in that: The method for preparing the nano Mn@TiO2 photocatalyst in step (2) comprises the following specific steps: 1) dissolving tetrabutyl titanate in anhydrous ethanol to obtain a tetrabutyl titanate solution; 2) adding manganese acetate to tetrabutyl titanate solution and performing ultrasonic dispersion to obtain a slurry; 3) The slurry is woven into a fiber membrane by electrospinning, and the fiber membrane is calcined at a temperature of 400-1000° C. in an argon atmosphere for 60-120 min to obtain a highly active nano-Mn@TiO2 photocatalyst.

6. The method for degrading and separating organic matter on the surface of bauxite according to claim 5, characterized in that: In the step 1), the volume ratio of tetrabutyl titanate to anhydrous ethanol is 1 to 4:

6.

7. The method for degrading and separating organic matter on the surface of bauxite according to claim 5, characterized in that: In the step 2), the ultrasonic power is 110-660 W, the frequency is 40 kHz, and the solid-liquid ratio of manganese acetate to tetrabutyl titanate solution is 0.5-1.4:4 g:mL.

8. The method for degrading and separating organic matter on the surface of bauxite according to claim 1, characterized in that: The concentration of lime water in step (3) is 6 to 15 g / L, and the volume ratio of lime water to alkaline liquid containing Na2CO3 is 1 to 6:5.