阅读说明：本技术 一种蒸氨废水处理的方法 (Method for treating ammonia distillation wastewater ) 是由 陈永涛 张成义 杨益 王晶 杨婧 于 2021-09-18 设计创作，主要内容包括：本发明属于工业废水处理技术领域,具体的说属于氨碱法生产纯碱废水处理方法。一种蒸氨废水处理的方法,在废水处理过程中加入草酸钾以分离出废水中所含的钙离子。在废水处理过程中产生的副产品包括：草酸钙、氯化钾、石膏中的一种或多种。在废水处理过程中所得泥浆用于烟气脱硫。本发明的目的在于克服现有的蒸氨废水处理工艺技术的不足,提供一种新的氨废水处理工艺流程,实现蒸氨废水中水回用、废渣利用、钙、钠、镁等元素的回收的目的,极大的提高了水资源的利用率,对纯碱厂周边以及整个区域内的环境保护具有重大意义。(The invention belongs to the technical field of industrial wastewater treatment, and particularly belongs to a treatment method of wastewater generated in the production of soda by an ammonia-soda process. A method for treating ammonia evaporation wastewater, wherein potassium oxalate is added in the wastewater treatment process to separate calcium ions contained in the wastewater. Byproducts generated during wastewater treatment include: one or more of calcium oxalate, potassium chloride and gypsum. The slurry obtained in the wastewater treatment process is used for flue gas desulfurization. The invention aims to overcome the defects of the existing ammonia distillation wastewater treatment process technology, provides a new ammonia wastewater treatment process flow, realizes the purposes of water reuse, waste residue utilization, calcium, sodium, magnesium and other elements in the ammonia distillation wastewater, greatly improves the utilization rate of water resources, and has great significance for environmental protection around a soda plant and in the whole area.)

1. A method for treating ammonia distillation wastewater is characterized by comprising the following steps: adding potassium oxalate in the wastewater treatment process to separate calcium ions contained in the wastewater.

2. The method for treating ammonia distillation wastewater according to claim 1, wherein the method comprises the following steps: byproducts generated during wastewater treatment include: one or more of calcium oxalate, potassium chloride and gypsum.

3. The method for treating ammonia distillation wastewater according to claim 2, wherein the method comprises the following steps: the slurry obtained in the wastewater treatment process is used for flue gas desulfurization.

4. The method for treating ammonia distillation wastewater according to claim 3, wherein the method comprises the following steps: the method comprises the following process flows:

a. carrying out solid-liquid separation on the ammonia distillation wastewater stock solution by adopting a solid-liquid separation technology to obtain supernatant and slurry;

b. the supernatant enters an evaporator for evaporation and concentration to obtain an evaporation condensate and an evaporation concentrate, and the condensate can be used as production water to return to a soda production system;

c. carrying out double decomposition reaction on the potassium oxalate solution and the evaporation concentrated solution obtained in the step (b) in a reactor to obtain calcium oxalate precipitate;

d. carrying out solid-liquid separation on the mixed solution containing calcium oxalate precipitate obtained after the reaction is finished to obtain calcium oxalate and separation mother liquor;

e. the separated mother liquor enters a crystallizer for cold crystallization to obtain mixed liquor containing potassium chloride (solid);

f. the mixed solution containing potassium chloride (solid) enters a separator for solid-liquid separation to obtain potassium chloride (solid) and concentrated solution containing NaCl; the NaCl-containing concentrated solution can be returned to a soda production system to be used as a soda production raw material;

g. adding the slurry obtained in the step (a) into production water in a mixer, continuously stirring and slurrying to obtain white slurry;

h. and filtering the obtained white mud slurry in a filter to obtain high-purity white mud slurry and filter residue.

5. The method for treating ammonia distillation wastewater according to claim 4, wherein the method comprises the following steps: also comprises feeding the white mud slurry into an absorption tower for flue gas desulfurization, and removing SO in the filtered flue gas₂To obtain a product containing CaSO₃And (3) slurry.

6. The method for treating ammonia distillation wastewater according to claim 5, wherein the method comprises the following steps: will contain CaSO₃And (3) enabling the slurry to enter a gypsum reaction tank to carry out oxidation reaction with compressed air to obtain gypsum slurry.

7. The method for treating ammonia distillation wastewater according to claim 4, wherein the method comprises the following steps: the stock solution of the ammonia distillation wastewater contains CaCl₂、NaCl、NH₃-N, over-burnt CaO (solid), CaCO₃、Mg(OH)₂(solid), CaSO₄One or more of (solid).

8. The method for treating ammonia distillation wastewater according to claim 4, wherein the method comprises the following steps: the turbidity of the supernatant after the solid-liquid separation of the ammonia distillation wastewater stock solution is less than or equal to 2NTU, so as to prevent impurities from influencing the evaporation effect.

9. The method for treating ammonia distillation wastewater according to claim 4, wherein the method comprises the following steps: potassium oxalate and CaCl in evaporated concentrate₂The mass ratio of (A) to (B) is 1.45.

10. The method for treating ammonia distillation wastewater according to claim 4, wherein the method comprises the following steps: the specific process flow of the step k is as follows: containing CaSO₃The slurry enters from the upper part of the gypsum reaction tank, the compressed air is introduced into the gypsum reaction tank through an air distribution pipe arranged in the gypsum reaction tank, and the air entering the gypsum reaction tank forms tiny air bubbles under the action of a slurry stirrer and uniformly penetrates through the CaSO-containing water₃Slurry, the CaSO in the pool₃Oxidation to CaSO₄Newly generated CaSO₄Crystallizing and forming crystals (CaSO) in gypsum seed crystals₄·2H₂O)。

Technical Field

The invention belongs to the technical field of industrial wastewater treatment, and particularly relates to a treatment method of wastewater generated in the production of soda by an ammonia-soda process.

Background

The production of soda ash by ammonia-soda process has large production scale and large discharge capacity (about 10.8m of ammonia distillation wastewater is generated per 1 ton of soda ash produced)³) And the difficulty of sewage and wastewater treatment is high. Large-scale ammonia and alkali plants in China are built at seaside, and the main purpose is to facilitate the treatment of discharged waste liquid and waste residue. The method for treating the ammonia distillation wastewater at present mainly comprises the steps of building a slag field, namely building a dam dike by using earthwork, conveying the ammonia distillation wastewater into the dam, naturally settling the ammonia distillation wastewater, naturally carbonizing the ammonia distillation wastewater, and discharging the ammonia distillation wastewater after indexes such as the pH value and the turbidity of clear liquid are qualified.

With the continuous development of the industry of producing soda by the ammonia-soda process and the continuous improvement of the national requirement on environmental protection, the recycling of elements such as water reuse, waste residue utilization and calcium, sodium, magnesium and the like in the treatment of ammonia evaporation wastewater generated in the production of soda by the ammonia-soda process is a new development trend.

Disclosure of Invention

The invention aims to overcome the defects of the existing ammonia distillation wastewater treatment process technology, provides a new ammonia wastewater treatment process flow, realizes the purposes of water reuse, waste residue utilization, calcium, sodium, magnesium and other elements in the ammonia distillation wastewater, greatly improves the utilization rate of water resources, and has great significance for environmental protection around a soda plant and in the whole area.

In order to achieve the purpose, the invention adopts the following technical scheme: a method for treating ammonia distillation wastewater comprises the following process flows:

a. carrying out solid-liquid separation on the ammonia distillation wastewater stock solution by adopting a solid-liquid separation technology to obtain supernatant and slurry;

b. the supernatant enters an evaporator for evaporation and concentration to obtain an evaporation condensate and an evaporation concentrate, and the condensate can be used as production water to return to a soda production system;

c. carrying out double decomposition reaction on the potassium oxalate solution and the evaporation concentrated solution obtained in the step (b) in a reactor to obtain calcium oxalate precipitate;

d. carrying out solid-liquid separation on the mixed solution containing calcium oxalate precipitate obtained after the reaction is finished to obtain calcium oxalate and separation mother liquor;

e. the separated mother liquor enters a crystallizer for cold crystallization to obtain mixed liquor containing potassium chloride (solid);

f. the mixed solution containing potassium chloride (solid) enters a separator for solid-liquid separation to obtain potassium chloride (solid) and a concentrated solution containing NaCl, wherein the purity of the potassium chloride is more than or equal to 98 percent; the NaCl-containing concentrated solution can be returned to a soda production system to be used as a soda production raw material;

g. adding the slurry obtained in the step (a) into production water in a mixer, continuously stirring and slurrying to obtain white slurry;

h. filtering the obtained white mud slurry in a filter to obtain high-purity white mud slurry and filter residue;

i. the white mud enters an absorption tower to be desulfurized with the boiler flue gas, and SO in the filtered flue gas is removed₂To obtain a product containing CaSO₃Slurry;

j. will contain CaSO₃And (3) enabling the slurry to enter a gypsum reaction tank to carry out oxidation reaction with compressed air to obtain gypsum slurry.

Further, the stock solution of the ammonia distillation wastewater contains CaCl₂、NaCl、NH₃-N, over-burnt CaO (solid), CaCO₃、Mg(OH)₂(solid), CaSO₄(solid);

further, the ammonia distillation wastewater stoste solid-liquid separation method comprises but is not limited to the following steps: HVM membrane separation, Goll membrane separation and thickener separation.

Furthermore, the turbidity of the supernatant after the solid-liquid separation of the ammonia distillation wastewater stock solution is less than or equal to 2NTU, so as to prevent impurities from influencing the evaporation effect.

Further, methods for evaporative concentration of the supernatant include, but are not limited to: multiple-effect falling film evaporation and MVR evaporation. Further, the evaporation amount of the supernatant was 40%.

Further, the potassium oxalate solution is prepared to be 38% (wt) of saturated solution so as to ensure the reaction speed.

Further, potassium oxalate and CaCl in the evaporated and concentrated solution₂The mass ratio of (a) to (b) is 1.45, so that the phenomenon that the mixed solution containing calcium oxalate precipitates contains oxalate due to the addition of excessive potassium oxalate in the reaction process is prevented.

Further, the solid-liquid separation method of the mixed liquor containing the calcium oxalate precipitate includes but is not limited to: centrifuge separation, horizontal belt type machine separation and plate and frame filter press separation.

Further, the crystallizer can be one or more of an air cooling crystallizer, a barrel-tube crystallizer, a jacket spiral belt crystallizer, a conical jacket crystallizer and a grading crystallizer;

further, the solid-liquid separation method of the mixed liquid containing potassium chloride (solid) comprises horizontal time-lapse separation and centrifugal separation.

Further, the mixer can be selected from a plough blade mixer and a single cone double helix mixer.

Further, the filter can be a filter drum screen.

Furthermore, the absorption tower adopts advanced and reliable empty tower spraying. The flue gas directly enters an absorption tower, is rectified and crushed by a grating, rises along the tower and undergoes 3 layers of desulfurization slurry atomization spraying, and the liquid-gas ratio is 16L/Nm³。

Further, containing CaSO₃The slurry enters from the upper part of the gypsum reaction tank, the compressed air is introduced into the gypsum reaction tank through an air distribution pipe arranged in the gypsum reaction tank, and the air entering the gypsum reaction tank forms tiny air bubbles under the action of a slurry stirrer and uniformly penetrates through the CaSO-containing water₃Slurry, the CaSO in the pool₃Oxidation to CaSO₄Newly generated CaSO₄Crystallizing and forming crystals (CaSO) in gypsum seed crystals₄·2H₂O)。

The technical scheme adopted by the invention has the following beneficial effects:

1. the invention recycles the water resource in the ammonia distillation wastewater;

2. the invention recovers a large amount of sodium elements, reduces the production cost of producing the soda by the ammonia-soda process;

3. the invention separates calcium element to be fully utilized;

d. the invention has the advantages that the high-purity calcium oxalate and potassium chloride products are produced;

the method realizes the comprehensive utilization of the ammonia distillation wastewater generated in the production of the soda by the ammonia-soda process, has important significance for environmental protection and production cost reduction, and has obvious beneficial effects.

Drawings

FIG. 1 is a process flow diagram of one embodiment of the present invention.

Detailed Description

The technical scheme of the invention is further explained by combining the drawings and the specific embodiments as follows:

the preferred embodiment of the invention provides a method for treating ammonia distillation wastewater. The method for treating the ammonia distillation wastewater comprises the following steps:

a. carrying out solid-liquid separation on the ammonia distillation wastewater stock solution by adopting a solid-liquid separation technology to obtain supernatant and slurry, wherein the solid content of the slurry is 50% (wt);

b. the supernatant enters an evaporator for evaporation and concentration to obtain an evaporation condensate and an evaporation concentrate, and the condensate can be used as production water to return to a soda production system;

c. carrying out double decomposition reaction on 38% (wt) potassium oxalate solution and the evaporation concentrated solution obtained in the step (b) in a reactor to obtain calcium oxalate precipitate;

d. carrying out solid-liquid separation on the mixed solution containing calcium oxalate precipitate obtained after the reaction is finished to obtain calcium oxalate and separation mother liquor;

e. the separated mother liquor enters a crystallizer for cold crystallization to obtain mixed liquor containing potassium chloride (solid);

f. the mixed solution containing potassium chloride (solid) enters a separator for solid-liquid separation to obtain potassium chloride (solid) and a concentrated solution containing NaCl, wherein the purity of the potassium chloride is more than or equal to 98 percent; the NaCl-containing concentrated solution can be returned to a soda production system to be used as a soda production raw material;

g. adding the slurry containing 50% of solids obtained in the step (a) into production water in a mixer, continuously stirring and slurrying to obtain white slurry with the concentration of about 20% (wt);

h. filtering the obtained white mud slurry with the concentration of about 20 percent (wt) in a filter to obtain high-purity white mud slurry and filter residue;

i. the white mud with the concentration of about 20 percent (wt) enters an absorption tower to be desulfurized with the boiler flue gas, and SO in the filtered flue gas is removed₂To obtain a product containing CaSO₃Slurry;

j. containing CaSO₃The slurry enters from the upper part of the gypsum reaction tank, the compressed air is introduced into the gypsum reaction tank through an air distribution pipe arranged in the gypsum reaction tank, and the air entering the gypsum reaction tank forms tiny air bubbles under the action of a slurry stirrer and uniformly penetrates through the CaSO-containing water₃Slurry, the CaSO in the pool₃Oxidation to CaSO₄Newly generated CaSO₄Crystallizing and forming crystals (CaSO) in gypsum seed crystals₄·2H₂O)。

k. The white mud filter residue and gypsum slurry can be used as building materials.

The ammonia distillation wastewater stock solution solid-liquid separation method is separation by a thickener.

The turbidity of the supernatant after the solid-liquid separation of the ammonia distillation wastewater stock solution is less than or equal to 2NTU, so that the evaporation effect is prevented from being influenced by impurities.

The evaporation and concentration method of the supernatant is MVR evaporation.

The evaporation capacity of the supernatant was 40%.

The potassium oxalate solution is 38% (wt) of saturated solution to ensure the reaction speed.

The potassium oxalate and CaCl in the evaporation concentrated solution₂The mass ratio of (a) to (b) is 1.45, so that the phenomenon that the mixed solution containing calcium oxalate precipitates contains oxalate due to the addition of excessive potassium oxalate in the reaction process is prevented.

The solid-liquid method of the mixed liquid containing the calcium oxalate precipitate is plate-and-frame filter press separation.

The solid-liquid separation method of mixed liquor containing potassium chloride (solid) includes horizontal separation at a certain time and centrifugal separation.

The slurry mixer containing 50% of solid can be selected from a plough blade mixer and a single cone double screw mixer.

The crystallizer is a barrel-tube crystallizer.

The white mud filter with a concentration of 20% (wt) can be selected from a filter screen.

Further, the technical scheme provided by the invention also comprises flue gas desulfurization treatment, and the specific scheme is that the absorption tower adopts advanced and reliable empty tower spraying. The flue gas directly enters an absorption tower, is rectified and crushed by a grating, rises along the tower and undergoes 3 layers of desulfurization slurry atomization spraying, and the liquid-gas ratio is 16L/Nm³。

In conclusion, the technical scheme adopted by the invention has the following obvious beneficial effects: the invention recycles the water resource in the ammonia distillation wastewater; a large amount of sodium elements are recovered, so that the production cost of producing the calcined soda by the ammonia-soda process is reduced; calcium element in the ammonia distillation wastewater is separated to be fully utilized. On the other hand, the technical scheme adopted by the invention has the advantages that high-purity calcium oxalate and potassium chloride products are produced;

the method realizes the comprehensive utilization of the ammonia distillation wastewater in the production of the soda ash by the ammonia-soda process, has important significance for environmental protection and production cost reduction, and has obvious beneficial effects.