TWI653196B - A method of synthesizing homogeneous aluminum-containing crystals by using fluidized-bed crystallization technology - Google Patents

Abstract

The present invention relates to a method for synthesizing homogeneous aluminum-containing crystals by fluidized bed crystallization techniques. In addition to the efficient removal of aluminum ions from wastewater, this method reduces the use of chemicals. This method does not require the use of a heterogeneous support in a fluidized bed reaction tank. Adjusting water quality conditions include aluminum ion feed concentration, pH value of hydroxide ion, molar ratio of hydroxide ion to aluminum ion, pH value of effluent and upflow velocity, and recovery of aluminum salt by fluidized bed homogenization crystallization system Crystallized particles to remove aluminum ions from the wastewater. The treatment efficiency obtained by the method is high and the purity of the crystal particles is high, and has high utilization potential.

Description

Method for synthesizing homogeneous aluminum-containing crystals by fluidized bed crystallization technique

The invention relates to a method for synthesizing homogeneous aluminum-containing crystals by fluidized bed crystallization technology, in particular to a method for recovering high concentration aluminum metal in waste water into aluminum oxide particles by fluidized bed homogenization granulation technology, which is suitable for aluminum The processing of aluminum, waste water generated in the process of profile, waste optical disc resource recycling and electroplating industry is conducive to subsequent processing and reuse.

It is known that the treatment of aluminum-containing waste liquid is generally carried out by flocculation and sedimentation by adding a flocculating agent such as polyaluminum or polypropylene decylamine, or recovering aluminum in the wastewater by using sodium hydroxide as a precipitating agent.

In the mainland patent CN 103420520 B "a treatment method for vanadium-containing aluminum-containing wastewater", it is disclosed that: (1) the vanadium-containing aluminum-containing wastewater is contacted with an alkaline substance under the conditions of vanadium precipitation and aluminum precipitation, and the product after contact Performing solid-liquid separation to obtain a vanadium-containing aluminum-containing solid product and a filtrate; (2) subjecting the filtrate obtained in the step (1) to reverse osmosis treatment to obtain a reverse osmosis product water and concentrated water, and returning the concentrated water to the step (1) )in.

In the mainland patent CN 103818985 B "a method for recycling aluminum-containing waste hydrochloric acid", it is disclosed that: (1) a hydrochloric acid solution having a hydrochloric acid content of 14 to 20% and an aluminum ion content of 15 to 30% is subjected to sand filtration to remove solid suspension. (2) ion exchange through an anion exchange resin column at an operating temperature of 45 to 50 ° C and a flow rate control of 100 to 120 L/min, and (3) collecting the effluent after the step 2 treatment to In the precipitation tank, an oxidizing agent is added for oxidation, and (4) a precipitating agent is added to the oxidizing liquid treated in the step 3 to precipitate, and the aluminum sludge is obtained by pressure filtration.

In the Continental patent CN1111682 "Waste treatment method for aluminum surface treatment", it is disclosed that the aluminum-containing waste liquid produced by treating the material with an alkali or an acid solution is neutralized and the slurry of the aqueous aluminum hydroxide gel is separated.

In the mainland patent CN1413929 "New process for sludge disposal of aluminum-containing wastewater treatment system", it is revealed that the aluminum-containing wastewater enters the grit chamber for grit treatment before entering the sedimentation tank, and the siphon mud machine is sucked out from the sedimentation tank. The sewage separated by the underflow sludge and the sand water separator and the reclaimed water obtained by filtering a part of the screening program are pumped as backwash water to the dehydration heater to heat the sludge hot water, and then The sludge hot water is used for the two red mud washing and sedimentation to recover the Na2O and Al2O3 attached to the red mud, and the washing liquid containing Na2O and Al2O3 after washing the red mud is sent to the alumina production process for reuse.

In the mainland patent CN102627362A "a process for recovering aluminum hydroxide from acidic wastewater containing aluminum ions", it is disclosed that the acidic wastewater containing aluminum ions is pretreated, followed by neutralization to completely convert aluminum ions into insoluble aluminum hydroxide, and then After slow stirring at the neutralization temperature, the solid-liquid separation, the wastewater discharge to the standard, and the insoluble aluminum hydroxide sludge is recycled.

In the mainland patent CN103936041A "a method for recycling and utilizing aluminum-containing waste sulfuric acid", it is disclosed that the aluminum-containing waste sulfuric acid is first treated by a rotary evaporator to make the sulfuric acid concentration greater than 70%; and the ratio of solid-liquid waste sulfur to scrap steel Adding scrap steel slag to the concentrated aluminum-containing waste sulfuric acid on the basis of mL:g; operating temperature is 50-100 ° C, reaction time is 1-3 h; hydrogen recovery generated in the reaction is used to provide heat source for the reaction; Solid-liquid separation, combined impurity removal, crystallization, and calcination to obtain alumina and iron oxide solids.

In the Continental patent CN104609615A "a treatment method for wastewater containing heavy metal surface treatment", it is disclosed that, by collecting waste water, sodium hydroxide is added to remove phosphate in a single reaction step, and sodium hydroxide is added in a second reaction step to remove aluminum ions.

In Taiwan's invention patent I415950 "Aluminum salt recovery and concentration method and system containing aluminum sludge" is disclosed: the acid-containing aluminum salt sludge produced by the coagulation process of the water purification plant is acidified to dissolve Al ³⁺ , and solid-liquid The Al ³⁺ solution is separated, and the aluminum-containing sludge is also alkalized to alkalinize Al(OH)4-, and the Al(OH)4-solution is obtained by solid-liquid separation. The two solutions are mixed to produce neutral non- Shaped Al(OH)3 precipitate.

The above conventional method for treating aluminum-containing waste liquid has the following technical problems: (a) the process is too complicated; (b) the use of the ion resin is expensive, the treatment cost is high; (c) the production of a large amount of sludge causes secondary pollution and subsequent Processing cost; and (d) using plate and frame filter press filter, because the aluminum hydroxide particles are too fine, it is still difficult to separate; it is easy to separate and reduce the recovery value when the filter aid is added.

At present, the treatment of heavy metal containing wastewater generated in the process of aluminum profile, waste optical disc resource recycling and electroplating industry is mainly handled by the main coagulation method. However, the chemical coagulation method is liable to generate a large amount of sludge, causing troubles in handling and increasing the cost of treating sludge. In addition, the traditional treatment program to remove heavy metals in water requires horizontally connected fast mixing tanks, slow mixing tanks, sedimentation tanks, and sludge dewatering machines. The required space is large and the amount of sludge generated is large, which has a considerable impact on the environment. Large, which in turn increases the trouble and burden of sludge treatment.

In order to improve the problem of chemical coagulation, a technique for recovering high-concentration metals in wastewater by using a fluidized bed crystallization procedure has been proposed, and the obtained high-concentration metal particles can be reused compared to conventional chemistry. Coagulation not only reduces costs, but also maintains the environment and reduces the hassle of tube disposal. However, the conventional "fluidized bed crystallization procedure" requires the addition of, for example, strontium sand or brick powder to the reaction vessel to carry out crystallization, thereby causing the carrier component to be contained in the metal crystal, and the crystal purity is poor, and the negative influence is reused. the value of. In addition, there is currently no related art for removing and recovering aluminum from wastewater using fluidized bed crystallization techniques.

Accordingly, the object of the present invention is to provide a method for synthesizing homogeneous aluminum-containing crystals by a fluidized bed crystallization technique, which can replace the chemical coagulation method to achieve an excellent aluminum removal effect, and the method does not require heterogeneity. The support, resulting in high purity of the aluminum-containing crystals, is beneficial for subsequent processing applications of aluminum recovery.

According to an embodiment of the invention, the method for synthesizing homogeneous aluminum-containing crystals by a fluidized bed crystallization technique comprises: providing a fluidized bed reaction tank having a lower section and an upper section, wherein the lower section is provided with a solution inflow a mouth and a medicament inlet, the upper section is provided with a water outlet for providing the effluent outflow after the reaction, and a reflux line is provided between the lower section and the upper section; the aluminum-containing solution and the granulating agent are individually introduced from the solution The flow port is mixed with the chemical inlet port into the fluidized bed reaction tank, wherein the granulating agent has hydroxide and the molar concentration ratio of the hydroxide to the aluminum ion of the aluminum solution is controlled between 1.5 and 7. The aluminum-containing solution mixed with the granulating agent flows from the lower portion of the reaction tank to the upper portion of the reaction tank, wherein the upward flow rate is controlled between 27 and 35 m·h ^-1 ; and the aluminum-containing solution of the mixed granulation agent is passed through The return line is refluxed to the lower stage for circulation such that the aluminum ions in the aluminum-containing solution react with the granulating agent to produce a homogeneous aluminum-containing crystal, wherein the effluent pH is controlled between 7 and 12.5.

Preferably, the aluminum ion feed concentration of the aluminum containing solution is controlled between 200 and 300 mg/L.

In a preferred embodiment, the ratio of the molar concentration of the hydroxide of the granulating agent to the aluminum ion of the aluminum-containing solution is controlled between 1.5 and 2.5, and the pH of the effluent is controlled between 7 and 9. . In another preferred embodiment, the molar ratio of the hydroxide of the granulating agent to the aluminum ion of the aluminum-containing solution is controlled between 5.5 and 6.5, and the pH of the effluent is controlled between 11 and 12. between

Preferably, the upflow speed is controlled between 28.5 and 32.5 m·h ^-1 .

In one embodiment, the pH of the granulating agent is controlled between 9 and 12.5.

In one embodiment, the hydraulic retention time is controlled between 10 and 30 minutes, and the cross-sectional load of the aluminum-containing solution is controlled to be between 0.3 and 2.0 kg m ^-2 h ^-1 .

Other objects, advantages and features of the present invention will become apparent from the description of the appended claims.

The invention provides a method for synthesizing homogeneous aluminum-containing crystals by fluidized bed crystallization technology, which uses granulation method to remove and recover aluminum in an aluminum-containing solution (for example, aluminum-containing wastewater), thereby reducing the use of chemical agents. There is no need to use a heterogeneous support, and the obtained aluminum-containing crystals have high purity, which is advantageous for subsequent processing applications. Furthermore, the method of the present invention is suitable for the treatment of aluminum-containing wastewater generated in the aluminum profile, the waste optical disk resource recycling process, and the electroplating process, thereby solving the pollution problem.

Referring to Figure 1, the process of the present invention first provides a fluidized bed reaction tank 10 having a tubular lower section 12 and a tubular upper section 14, the upper section 14 having an outer diameter greater than the outer diameter of the lower section 12. The bottom of the lower section 12 is provided with a solution inlet 16 and a medicament inlet 18. The upper section 14 is provided with a water outlet 20 for providing effluent outflow after the reaction, and a reflux between the lower section 12 and the upper section 14. A pump 24 is provided on the line 22 and the return line 22. In the present embodiment, the bottom end of the lower section 12 of the reaction tank 10 has a conical shape, which contributes to uniform dispersion of the return flow force. A pH value detector (not shown) is placed at the outlet 20 to monitor the effluent pH (pHe) while the water sample is collected for water quality analysis. Next, the aluminum-containing solution (for example, aluminum-containing wastewater) 30 and the granulating agent 32 are introduced into the lower stage 12 of the reaction tank 10 from the solution inlet port 16 and the chemical inlet port 18 by means of the pumps 26 and 28, respectively. Next, the aluminum-containing solution 30 mixed with the granulation agent 32 flows from the lower stage 12 to the upper stage 14, and is returned to the lower stage 12 via the return line 22 to be circulated, so that the aluminum ions in the aluminum-containing solution 30 are made The granule medicament 32 is subjected to a granulation reaction. In the present embodiment, the granulating agent 32 is sodium hydroxide, and the aluminum ions in the aluminum-containing solution 30 are used to generate poorly soluble aluminum oxide, and the characteristics of the granulation reaction are used to control the supersaturation. The range is such that the reaction in the reaction tank 10 produces a homogeneous aluminum-containing crystal (the crystals can be taken out from the crystal particle outlet 34) to remove the aluminum ions in the aluminum-containing solution 30. In a possible embodiment, the granulating agent 32 is a mixture of sodium carbonate (Na ₂ CO 3 ) and hydrogen peroxide (H ₂ O ₂ ), or may be other having a common property of producing crystals which can be used to reduce the solubility of aluminum. Hydrogen peroxide, but the use of sodium hydroxide as granulating agent 32 does not cause eutrophication and is harmless to the environment.

The aluminum ion feed concentration ([Al ³⁺ ] _in ) of the aluminum-containing solution 30, the feed molar ratio of the hydroxide of the granulation agent 32 to the aluminum ion of the aluminum-containing solution 30 according to the method of the present invention (MR) Of [OH ^- ] _in /[Al ³⁺ ] _in ), the pH value of the granulation agent 32 (pH (NaOH)), the pH value of the effluent (pHe), and the upstream velocity (U) of the hydraulic load will affect The aluminum ion removal rate (the aluminum removal efficiency) in the aluminum-containing solution 30 and the granulation rate (crystallization ratio) after the particles are stabilized. According to the test results, the aluminum ion feed concentration of the aluminum-containing solution is controlled to be between 100 and 400 mg/L, and the optimum control is between 200 and 300 mg/L mg/L; the granulation agent 32 of the hydroxide is relative to the aluminum-containing solution. The feed molar concentration ratio of 30 aluminum ions is controlled between 1.5 and 7, preferably between 1.5 and 2.5 and between 5.5 and 6.5; the pH value of the granulation agent 32 is controlled between 9 and 12.5. Preferably, the control is between 10 and 10.5 and between 12 and 12.5; the pH of the effluent is controlled between 7 and 12.5, preferably between 7 and 9 and between 11 and 12; The speed (U) is controlled between 27 and 35 m·h ^-1 and the optimum control is between 28.5 and 32.5 m·h ^-1 . Further, in the method of the present invention, the aluminum-containing solution 30 and the granulating agent 32 may be introduced into the reaction tank 10 to be mixed with the granulated agent 32 to produce a homogeneous aluminum-containing crystal particle. Body, in order to provide sufficient crystal growth surface area to facilitate the adhesion of newly produced crystal particles to regenerate new particles, so as to avoid the formation of gelatinous precipitates containing a large amount of water.

Referring to Fig. 2 and Fig. 3, respectively, the aluminum ion feed concentration in the aluminum-containing solution is 200, 300, 400 mg/L, and the pH value of the granulation agent 32 is 11.5, 11.8, 12.1, and the upper flow rate ( U) is 28.65m·h ^-1 , and the cross-section loading of the aluminum solution is 0.31-1.72 kg·m ^-2 h ^-1 , and the hydroxide of different granulating agents is relatively The effect of the molar ratio of the aluminum ion feed molar ratio of the aluminum solution to the aluminum removal efficiency (Al removal %) and the crystallization ratio (GR%). It has been found through experiments that in the operating conditions of the aluminum ion feed concentration of the aluminum-containing solution of 200 and 300 mg/L, the molar ratio of the hydroxide of the granulation agent 32 to the aluminum ion of the aluminum-containing solution 30 is controlled at Aluminogen removal efficiency and crystallization ratio of more than 90% can be obtained between 5.5 and 6.5. When the initial aluminum ion feed concentration of the aluminum-containing solution is 200 mg/L, the pH value of the granulation agent 32 is about 12.1, and the hydroxide of the granulation agent 32 is compared with the aluminum ion of the aluminum-containing solution 30. When the molar concentration ratio is 6, the ratio of aluminum ion removal to crystallization after particle stabilization is optimal (about 98% aluminum removal efficiency and about 96% crystallization ratio). When the initial aluminum ion feed concentration of the aluminum-containing solution is increased to 400 mg/L, the aluminum ion removal rate and the crystallization ratio after the particles are stabilized are relatively low.

Referring to Fig. 4, wherein (a) and (b) respectively show that the aluminum ion feed concentration in the aluminum-containing solution is 300 mg/L, the pH value of the granulation agent 32 is 10.0, 10.2, 10.4, and the upper flow rate ( U) is 32.47 m·h ^-1 , the hydraulic retention time (HRT) is 11.0 min and the cross-sectional loading (L) of the aluminum-containing solution is 1.15 kg·m ^-2 h ^-1 in the operating conditions of different granulating agents. The effect of the oxygen molar ratio of oxygen to the aluminum ion-containing aluminum ion feed molar ratio on the aluminum removal efficiency (Al removal %) and the crystallization ratio (GR%). It has been found through experiments that a higher aluminum removal efficiency and crystallization ratio (99%) can be obtained when the molar ratio of the hydroxide of the granulation agent 32 to the aluminum ion of the aluminum solution 30 is controlled between 1.5 and 2.5. The above aluminum removal efficiency is more than 93% of the crystal ratio).

In the operating conditions shown in Figures 2 and 3 (i.e., the molar ratio of the hydroxide of the granulating agent 32 to the aluminum ion of the aluminum-containing solution 30 is controlled between 5.5 and 6.5), an aluminum-containing product will be obtained. Tetracalcium dialuminum dodecahydroxide carbonate pentahydrate. While in the operating conditions shown in Figure 4 (i.e., the molar ratio of the hydroxide of the granulating agent 32 to the aluminum ion of the aluminum-containing solution 30 is controlled between 1.5 and 2.5), granulation of the alumina will be obtained. product. In the operating conditions of FIGS. 2 to 4, although high aluminum removal efficiency and crystallization ratio can be obtained, the hydroxide of the granulation agent 32 is relatively relative based on the viewpoint of saving chemicals and the discharge water complying with emission standards. The embodiment in which the molar concentration of the aluminum ion of the aluminum-containing solution 30 is controlled to be between 1.5 and 2.5 is preferred.

Referring to Figure 5, wherein (a), (b), and (c) respectively show aluminum ion feed concentrations of 200 mg/L, 300 mg/L, and 400 mg/L in the aluminum-containing solution, the hydroxide of the granulation agent 32 is relatively The molar ratio of the aluminum ions of the aluminum-containing solution 30 is 1.5, 2.0, 2.5, and the pH value of the granulating agent 32 is 10.0, 10.2, 10.4, and the cross-sectional load (L) of the aluminum-containing solution is 0.38. In the operating conditions of -3.06 kg·m ^-2 h ^-1 , the upflow velocity (U) is 28.65 m·h ^-1 , and the change in the pH of the effluent (pHe) is the concentration of aluminum soluble in the effluent (Al soluble concentration). And the effect of the total aluminum concentration in the effluent. It has been found through experiments that when the aluminum ion feed concentration of the aluminum-containing solution is 200 mg/L and the effluent pH (pHe) is controlled between 7 and 9, the aluminum soluble concentration in the effluent falls below 1 mg·L ^-1 . And the total concentration of aluminum in the effluent is reduced to below 0.5 mg·L ^-1 , because there are more particles formed, and thus there is an optimum aluminum removal efficiency and crystallization ratio. When the initial aluminum ion feed concentration of the aluminum-containing solution is increased to 400 mg/L, the aluminum ion removal rate and the crystallization ratio after the particles are stabilized are relatively low.

Referring to Fig. 6, wherein (a) and (b) respectively show that the aluminum ion feed concentration of the aluminum-containing solution is 200 mg/L, and the hydroxide of the granulation agent 32 is compared with the aluminum ion of the aluminum-containing solution 30. The concentration ratio is 5.5, 6.0, 6.5, and the pH value of the granulating agent 32 is 11.5, 11.8, 12.1, the upper flow velocity (U) is 28.65 m·h ^-1 , and the cross-sectional load of the aluminum-containing solution is 0.31- Effect of different effluent pH (pHe) on the aluminum soluble concentration in the effluent and the total aluminum concentration in the effluent during the operating conditions of 1.72 kg·m ^-2 h ^-1 . It has been found through experiments that when the pH of the effluent (pHe) is controlled between 11.5 and 12.5, the aluminum ion removal rate and the crystallization ratio after the particles are stabilized are relatively high. When the pH of the effluent increased to 11.8, the soluble concentration of aluminum in the effluent decreased to 0.48 mg·L ^-1 , and the total concentration of aluminum in the effluent decreased to 0.53 mg·L ^-1 , because there were more particles. Formed, thus having the best aluminum removal efficiency and crystallization ratio. When the pH of the effluent increased to 11.96, the soluble concentration of aluminum in the effluent rose to 3.41 mg·L ^-1 , and the total concentration of aluminum in the effluent rose to 6.34 mg·L ^-1 because of nuclear particles (nuclei). Particles) decompose at higher effluent pH values, resulting in reduced aluminum removal efficiency. In addition, when the pH of the effluent is lower than 10, the aluminum soluble concentration and the total aluminum concentration in the effluent increase, resulting in a relatively low aluminum ion removal rate and crystallization ratio.

In the operating conditions shown in Figure 5 (i.e., the pH of the effluent is controlled between 7 and 9), a granulated product of alumina will be obtained. While in the operating conditions shown in Figure 6 (i.e., the effluent pH is controlled between 11.5 and 12.5), another tetracalc dialuminum dodecahydroxide carbonate pentahydrate will be obtained. In the operating conditions of Figures 5 and 6, although high aluminum removal efficiency and crystallization ratio can be obtained, the pH of the effluent is controlled to 7 to 9 based on the viewpoint of chemical saving and the discharge water complying with emission standards. The embodiment between them is preferred.

Referring to Fig. 7, wherein (a) and (b) respectively show that the aluminum ion feed concentration of the aluminum-containing solution is 200 mg/L, and the hydroxide of the granulation agent 32 is compared with the aluminum ion of the aluminum-containing solution 30. The concentration ratio is 5.5, 6.0, 6.5, and the pH value of the granulating agent 32 is 11.5, 11.8, 12.1, and the cross-sectional loading of the aluminum-containing solution is 0.31 kg·m ^-2 h ^-1 and the hydraulic retention time (HRT). The effect of the upstream speed (U) of different hydraulic loading on the aluminum removal efficiency (Al removal %) and the crystallization ratio (GR%) was controlled in the operating conditions of 11 min. It has been found through experiments that when the upflow velocity (U) is controlled between 27 and 38 m·h ^-1 , an aluminum removal efficiency and a crystallization ratio of more than 90% can be obtained. When the upper flow velocity (U) is controlled at 32.47 m·h ^-1 , the molar ratio of the hydroxide of the granulating agent 32 to the aluminum ion of the aluminum-containing solution 30 is 6 and the pH of the granulating agent 32 ( When the pH is about 12.1, the aluminum ion removal rate is the best as the crystallization ratio after the particles are stabilized (about 98% of the aluminum removal efficiency and about 96% of the crystallization ratio). When the upflow velocity (U) drops below 27 mh ^-1 , the aluminum ion removal rate is relatively low compared to the crystallization ratio after the particles are stabilized.

Referring to Fig. 8, wherein (a) and (b) respectively show that the initial aluminum ion feed concentration of the aluminum-containing solution is 300 mg/L, and the hydroxide of the granulation agent 32 is opposite to the aluminum ion of the aluminum-containing solution 30. The ear concentration ratio is 5.5, 6.0, 6.5, and the pH value of the granulating agent 32 is 11.5, 11.8, 12.1, and the cross-sectional loading of the aluminum-containing solution is 0.31 kg·m ^-2 h ^-1 and the hydraulic retention time (HRT) Controlling the effect of the upstream speed (U) of different hydraulic loads on the aluminum removal efficiency (AL REMOVAL%) and the crystallization ratio (GR%) in the operating conditions of 11 min. It has been found through experiments that when the upflow velocity (U) is controlled between 27 and 38 m·h ^-1 , an aluminum removal efficiency and a crystallization ratio of more than 90% can be obtained. When the molar ratio of the hydroxide of the granulating agent 32 to the aluminum ion of the aluminum-containing solution 30 is 6 and the pH value of the granulating agent 32 is 11.8, the aluminum ion removal rate and the particle stability are stabilized. The crystallization ratio is the best (about 96% of the aluminum removal efficiency and about 94% of the crystallization ratio).

Referring to Fig. 9, wherein (a) and (b) respectively show that the aluminum ion feed concentration of the aluminum-containing solution is 400 mg/L, and the hydroxide of the granulation agent 32 is compared with the aluminum ion of the aluminum-containing solution 30. The concentration ratio is 5.5, 6.0, 6.5, the pH value of the granulating agent 32 is 11.5, 11.8, 12.1, the cross-sectional loading of the aluminum-containing solution is 0.31 kg·m ^-2 h ^-1 and the hydraulic retention time is controlled at 11 min. The effect of the upstream speed (U) of different hydraulic loads on the aluminum removal efficiency (Al removal %) and the crystallization ratio (GR%) in the operating conditions. It has been found through experiments that when the upflow velocity (U) is controlled between 27 and 38 m·h ^-1 , an aluminum removal efficiency and a crystallization ratio of more than 80% can be obtained. When the molar ratio of the hydroxide of the granulating agent 32 to the aluminum ion of the aluminum-containing solution 30 is 6 and the pH value of the granulating agent 32 is 11.5, the aluminum ion removal rate and the particle stability are stabilized. The crystallization ratio is the best (about 90% of the aluminum removal efficiency and about 90% of the crystallization ratio).

Referring to Fig. 10, wherein (a) and (b) respectively show that the initial aluminum ion feed concentration of the aluminum-containing solution is 300 mg/L, and the hydroxide of the granulation agent 32 is compared with the aluminum ion of the aluminum-containing solution 30. The ear concentration ratio is 1.5, 2.0, 2.5, and the pH value of the granulating agent 32 is 10.0, 10.2, 10.4, and the cross-sectional loading of the aluminum-containing solution is 0.86 kg·m ^-2 h ^-1 and the hydraulic retention time (HRT) Controlling the effect of the upstream speed (U) of different hydraulic loads on the aluminum removal efficiency (Al removal %) and the crystallization ratio (GR%) in the operating conditions of 11 min. It has been found through experiments that when the upflow velocity (U) is controlled between 20 and 27 m·h ^-1 , an aluminum removal efficiency and a crystallization ratio of more than 90% can be obtained. When the molar ratio of the hydroxide of the granulating agent 32 to the aluminum ion of the aluminum-containing solution 30 is 2.5 and the pH value of the granulating agent 32 is 10.4, the aluminum ion removal rate and the particle stability are stabilized. The crystallization ratio is the best (about 99% of the aluminum removal efficiency and about 96% of the crystallization ratio).

In the operating conditions shown in Figures 7-9 (i.e., the ratio of the molar concentration of the hydroxide of the granulating agent 32 to the aluminum ion of the aluminum-containing solution 30 is controlled between 5.5 and 6.5), a tetracalcium aluminum ten is obtained. Granulated product of dicalcium carbonate dihydrate pentahydrate. While in the operating conditions shown in Figure 10 (i.e., the molar ratio of the hydroxide of the granulating agent 32 to the aluminum ion of the aluminum-containing solution 30 is controlled between 1.5 and 2.5), granulation of the alumina will be obtained. product.

Referring to Fig. 11, wherein (a) and (b) respectively show that the aluminum ion feed concentration in the aluminum-containing solution is 300, 400 mg/L, respectively, the hydroxide of the granulation agent 32 is in contact with the aluminum ion of the aluminum-containing solution 30. The molar concentration ratio of the molars is 1.5, 2.0, 2.5, the pH value of the granulating agent 32 is 10.0, 10.2, 10.4, and the hydraulic retention time (HRT) is controlled under the operating conditions of 11 min. The effect of load (L) on aluminum removal efficiency (Al removal %) and crystallization ratio (GR%). It has been found that high aluminum ion removal rate and crystallization ratio can be obtained when the cross-sectional load of the aluminum-containing solution is controlled between 1.2 and 2.5 kg m ^-2 h ^-1 .

From the above results, the method of the present invention adopts fluidized bed homogenization crystallization technology, and adjusts the water quality conditions including the aluminum ion feed concentration of the aluminum-containing solution, and the granulation agent (hydrogen ion) relative to the aluminum ion of the aluminum-containing solution. The concentration ratio of the molar concentration, the pH value of the granulation agent 32, the pH value of the effluent (pHe), and the upward flow rate of the hydraulic load are optimally conditioned, and the aluminum-containing wastewater can be rectified to achieve high-efficiency removal of aluminum ions in the water. In order to meet the discharge water standard, and to recover aluminum-containing crystals, it can be effectively reused. In particular, according to the method of the present invention, when the initial aluminum ion feed concentration of the aluminum-containing solution is controlled at 200-300 mg/L, the hydroxide of the granulation agent 32 is compared with the aluminum ion of the aluminum-containing solution 30. The concentration ratio is controlled between 1.5 and 2.5 and between 5.5 and 6.5, and the pH value of the granulation agent 32 is controlled between 10 and 10.5 and between 12 and 12.5, and the pH value of the effluent is controlled. Between 7 and 9 and between 11 and 12; the upstream velocity (U) is controlled between 28.5 and 32.5 m·h ^-1 , and the cross-sectional load of the aluminum-containing solution is controlled between 1.2 and 2.5 kg m ^-2 h ^- Between ¹ , a relatively high removal efficiency and crystallization ratio will be obtained. In addition, the hydraulic retention time (HRT) also affects the removal rate of aluminum ions in the aluminum-containing solution 30 and the granulation rate after the particles are stabilized. It has been found experimentally that the hydraulic retention time (HRT) is controlled between 10 and 30 min. Furthermore, the method of the invention adopts a homogeneous nucleation crystallization technique, and does not need to first add a heterogeneous support in the fluidized bed reaction tank, so that the obtained aluminum-containing crystal has high purity, which is advantageous for subsequent processing applications. Therefore, the method of the invention can not only replace the chemical coagulation to achieve an excellent treatment effect, but also avoid the defects of the traditional chemical or biological methods, and achieve the purpose of product resource, and has the advantages of high efficiency, low cost, no sludge, and the like. .

In the foregoing specification, the invention has been described in terms of a particular embodiment, and various changes or modifications may be made in accordance with the features of the invention. Therefore, obvious substitutions and modifications may be made by those skilled in the art, and will still be incorporated in the scope of the claimed invention.

10‧‧‧Reaction tank

12‧‧‧ lower section

14‧‧‧上段

16‧‧‧ solution inlet

18‧‧‧Pharmaceutical inflow

20‧‧‧Water outlet

22‧‧‧Return line

24‧‧‧ pump

26‧‧‧

28‧‧‧

30‧‧‧Aluminum containing solution

32‧‧‧Plasting Agent

34‧‧‧ Crystal grain export

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a schematic illustration of an embodiment of a fluidized bed reaction vessel provided by the process of the present invention.

2 is a diagram showing the feed of the aluminum ions of the different granulating agents relative to the aluminum ions of the aluminum-containing solution under the operating conditions of the aluminum ion-containing aluminum ion feed concentrations of 200, 300, and 400 mg/L, respectively. A plot of the concentration ratio versus the effect of aluminum removal efficiency (Al removal %).

3 is a graph showing the molars of hydroxides of different granulating agents relative to aluminum ions of aluminum-containing solutions under operating conditions of aluminum ion-containing aluminum ion feed concentrations of 200, 300, and 400 mg/L, respectively. A plot of the effect of concentration ratio on the crystallization ratio (GR%).

(a) and (b) in FIG. 4 respectively show that the hydroxide of the granulating agent is opposite to the aluminum ion of the aluminum-containing solution under the operating conditions of the aluminum ion-containing aluminum ion feed concentration of 300. Another plot of the effect of ear concentration ratio change on the efficiency of aluminum removal (Al removal %) versus crystallization ratio (GR%).

(a), (b), and (c) in Fig. 5 show that the pH of the effluent changes for the operation under the operating conditions of the initial aluminum ion feed concentration of the aluminum-containing solution of 200, 300, and 400 mg/L, respectively. A plot of the effect of aluminum solubility in liquid on total aluminum concentration.

(a) and (b) in Fig. 6 show that the pH of the effluent changes for the aluminum soluble concentration and the total aluminum in the effluent under the operating conditions of the initial aluminum ion feed concentration of the aluminum-containing solution of 200 mg/L, respectively. Another diagram of the effect of concentration.

(a) and (b) in Fig. 7 respectively show the change of the upstream speed of the hydraulic load for the aluminum removal efficiency (Al removal %) and the crystallization ratio under the operating conditions of the aluminum ion-containing aluminum ion feed concentration of 200. (GR%) diagram of the impact.

(a) and (b) in Fig. 8 respectively show the change of the upstream speed of the hydraulic load for the aluminum removal efficiency (Al removal %) and the crystallization ratio under the operating conditions of the aluminum ion-containing aluminum ion feed concentration of 300. (GR%) diagram of the impact.

(a) and (b) in Fig. 9 are diagrams showing the change of the upstream speed of the hydraulic load for the aluminum removal efficiency (Al removal %) and crystallization under the operating conditions of the aluminum ion-containing aluminum ion feed concentration of 400, respectively. A diagram of the effect of the ratio (GR%).

(a) and (b) in Fig. 10 respectively show the change of the upstream speed of the hydraulic load for the aluminum removal efficiency (Al removal %) and the crystallization ratio under the operating conditions of the aluminum ion-containing aluminum ion feed concentration of 300. (GR%) Another diagram of the impact.

(a) and (b) in Fig. 11 show the cross-sectional loading (L) of different aluminum-containing solutions for the aluminum removal efficiency under the operating conditions of the initial aluminum ion feed concentration of the aluminum-containing solution of 300 and 400 mg/L, respectively. Relationship between (Al removal %) and crystallization ratio (GR%).

Claims (7)

A method for synthesizing homogeneous aluminum-containing crystals by a fluidized bed crystallization technique, comprising: providing a fluidized bed reaction tank having a lower section and an upper section, wherein the lower section is provided with a solution inlet port and a medicament inlet port, The upper section is provided with a water outlet for providing the effluent outflow after the reaction, and there is a return line between the lower section and the upper section, the reaction tank does not have a heterogeneous support; the aluminum-containing solution and the granulation agent are separately from the solution The inlet port is mixed with the chemical inlet port into the fluidized bed reaction tank, wherein the granulating agent has hydroxide and the molar concentration ratio of the hydroxide to the aluminum ion of the aluminum-containing solution is controlled between 1.5 and 7. The aluminum-containing solution mixed with the granulating agent flows from the lower portion of the reaction tank to the upper portion of the reaction tank, wherein the upstream flow rate is controlled at 27 to 35 m. Between h ^-1 ; and refluxing the aluminum-containing solution mixing the granulating agent to the lower stage via the reflux line to circulate, so that the aluminum ion in the aluminum-containing solution reacts with the granulating agent to produce a homogeneous aluminum-containing crystal, The pH of the effluent is controlled between 7 and 12.5. The method of claim 1, wherein the aluminum ion feed concentration of the aluminum-containing solution is controlled to be between 200 and 300 mg/L. The method of claim 1, wherein the ratio of the molar concentration of the hydroxide of the granulating agent to the aluminum ion of the aluminum-containing solution is controlled to be between 1.5 and 2.5, and the pH of the effluent is controlled at Between 7 and 9. The method of claim 1, wherein the ratio of the molar concentration of the hydroxide of the granulating agent to the aluminum ion of the aluminum-containing solution is controlled between 5.5 and 6.5, and the pH value of the effluent is controlled at Between 11 and 12. The method of claim 1, wherein the granulation agent has a pH of between 9 and 12.5. The method of claim 1, wherein the upper flow speed is controlled at 28.5 to 32.5 m. Between h ^-1 . The method of claim 1, wherein the hydraulic retention time is controlled between 10 and 30 minutes, and the cross-sectional load of the aluminum-containing solution is controlled to be between 0.3 and 2.0 kg m ^-2 h ^-1 .