CN112479467A - Graphite wastewater treatment device and use method thereof - Google Patents

Abstract

Translated fromChinese

一种石墨废水处理装置，该装置包括预处理系统、超滤系统、软化系统、纳滤系统、电渗析系统、反渗透系统和蒸发系统，预处理系统包括原水池、一级反应池、二级反应池、板框压滤机、沉淀池，沉淀池底部设有一条回流管道，清水进入后道系统；超滤系统经过预处理系统处理后清水进水超滤系统，超滤系统反洗水和浓缩液回流至一级反应池，软化系统设有一根回流管道，软化后软水进入后道系统；纳滤系统实现一二价离子分离，电渗析系统时对一级盐水进行浓缩制酸碱，浓水回电渗析再淡化处理；反渗透系二价盐水进行浓缩，淡水回用，浓水进入蒸发系统；本发明资源化工艺，针对废水进行深度综合利用，无其他副产品和废物产生，实现资源回收利用和零排放。

A graphite wastewater treatment device, the device includes a pretreatment system, an ultrafiltration system, a softening system, a nanofiltration system, an electrodialysis system, a reverse osmosis system and an evaporation system, and the pretreatment system includes a raw water pool, a primary reaction pool, a secondary The reaction tank, the plate and frame filter press, the sedimentation tank, and a return pipeline at the bottom of the sedimentation tank, and the clean water enters the subsequent system; after the ultrafiltration system is treated by the pretreatment system, the clean water enters the ultrafiltration system, and the ultrafiltration system backwash water and The concentrated liquid is returned to the first-level reaction tank, and the softening system is provided with a reflux pipeline. After softening, the softened water enters the subsequent system; the nanofiltration system realizes the separation of monovalent and divalent ions, and the first-level brine is concentrated to produce acid and alkali in the electrodialysis system. The water is recycled by electrodialysis and then desalinated; the reverse osmosis system divalent brine is concentrated, the fresh water is reused, and the concentrated water enters the evaporation system; the resource recycling process of the present invention conducts deep comprehensive utilization of waste water, and no other by-products and wastes are generated, realizing resource recycling and utilization and zero emissions.

Description

Graphite wastewater treatment device and use method thereof

Technical Field

The invention relates to a graphite wastewater treatment device and a use method thereof, belonging to the technical field of wastewater environment-friendly processes.

Background

The existing graphite wastewater treatment is that expanded graphite wastewater firstly enters a reaction triple box after the water quantity is regulated in a regulating tank, lime is added into a first reaction box of the reaction triple box to react with magnesium ions, fluorine ions and bicarbonate radicals in the saline wastewater, sodium carbonate is added into a second reaction box to precipitate calcium ions in the wastewater, then the wastewater enters a clarification tank to carry out solid-liquid separation to remove suspended matters in the wastewater, the effluent of the clarification tank enters expanded graphite reverse osmosis (the recovery rate is 75%) after passing through a multi-media filter and an ultrafiltration device, and the expanded graphite reverse osmosis produced water enters secondary reverse osmosis. And the expanded graphite reverse osmosis concentrated water enters the disc tube type reverse osmosis.

The method comprises the steps of firstly adjusting the water quantity of the wastewater of the three-acid method in an adjusting tank, then feeding the wastewater into a reaction three-header, adding lime into a first reaction box of the reaction three-header, reacting with magnesium ions, fluorine ions and bicarbonate radicals in the saline wastewater, adding sodium carbonate into a second reaction box, precipitating calcium ions in the wastewater, then feeding the wastewater into a clarification tank for solid-liquid separation, removing suspended matters in the water, mixing the effluent of the clarification tank with expanded graphite reverse osmosis concentrated water after passing through a multi-media filter and an ultrafiltration device, feeding the mixture into a disc-tube reverse osmosis (recovery rate is 50%), mixing the disc-tube reverse osmosis produced water with the expanded graphite reverse osmosis produced water, feeding the mixture into a second-stage reverse osmosis, and recycling the produced water.

In conclusion, the general enterprises take calcium chloride and calcium nitrate as building materials. However, in practice, so much waste salt is produced and cannot be disposed. Only piling up is needed. This solid waste still needs to be disposed of after a long time, so this technique has drawbacks.

Disclosure of Invention

The invention aims to solve the technical problem of overcoming the defects in the prior art and provides a graphite wastewater treatment device, and the purpose of the invention is achieved through the following technical scheme, the graphite wastewater treatment device comprises a pretreatment system, an ultrafiltration system, a softening system, a nanofiltration system, an electrodialysis system, a reverse osmosis system and an evaporation system which are sequentially connected, wherein the pretreatment system comprises a raw water tank, a primary reaction tank, a secondary reaction tank, a plate and frame filter press and a sedimentation tank which are sequentially connected, the bottom of the sedimentation tank is provided with a bottom mud return pipeline leading to the primary reaction tank, and clean water enters a subsequent pipeline; the clear water treated by the pretreatment system enters the water ultrafiltration system, backwash water and concentrated solution in the ultrafiltration system flow to the primary reaction tank through a return pipeline, and produced water enters a subsequent pipeline; the softening system is provided with a regeneration liquid return pipeline leading to the primary reaction tank, and softened soft water enters a subsequent pipeline; the nanofiltration system realizes the separation of divalent ions, wherein monovalent brine enters the electrodialysis system through a pipeline, and divalent brine enters the reverse osmosis system through a pipeline; the electrodialysis system consists of a homogeneous membrane electrodialysis cell and a bipolar membrane electrodialysis cell respectively, the electrodialysis system is used for concentrating primary saline water, the bipolar membrane system is used for preparing acid and alkali from electrodialysis concentrated saline water, fresh water of the electrodialysis system enters the reverse osmosis system for concentration, produced water is recycled, and concentrated water is returned to the electrodialysis system for desalination treatment; the reverse osmosis system is used for concentrating divalent brine and recycling fresh water.

Preferably, the method comprises the following steps: and a high-pressure reverse osmosis system is arranged on one side of the nanofiltration system, concentrated water is led into the evaporation system by the reverse osmosis system to be evaporated to obtain crystallized salt and condensed water, the crystallized salt is discharged outwards, the condensed water flows into a water production tank through a pipeline, and the produced water is led into the reverse osmosis system for advanced treatment.

A method for treating wastewater by a graphite wastewater treatment device comprises the following steps:

step 1, pretreatment, namely flowing water in a raw water tank into a first-stage reaction tank, adding calcium oxide between the first-stage reaction tank and a second-stage reaction tank, reacting in the second-stage reaction tank, extruding large calcium fluoride sludge through a plate-and-frame filter press, conveying away, adding sodium carbonate into the remaining aqueous solution, flowing into a sedimentation tank for sedimentation, and refluxing settled bottom mud into the first-stage reaction tank for circular reaction;

step 2, ultrafiltration filtration: adding acid into part of the solution in the sedimentation tank to adjust the pH value, introducing the solution into a super filter tank to carry out ultrafiltration reaction, refluxing part of concentrated solution after the reaction to a first-stage reaction tank for further reaction, and flowing the other part of the concentrated solution into a softening tank below the first-stage reaction tank.

Step 3, softening treatment: the produced water from the ultrafiltration system flows into a softening system, the softening system is softened by resin, the resin is regenerated by acid and alkali after being adsorbed and saturated, and the regenerated liquid flows into a primary reaction tank for carrying out treatment reaction;

step 4, nanofiltration system: produce water from ultrafiltration system and carry out the separation of divalent salt again through the system of receiving straining, the second grade salt water flows into the middling pressure reverse osmosis pond through the pipeline and carries out reverse osmosis, and during the electrodialysis system of first order salt moisture inflow bottom, in the concentrated water of middling pressure reverse osmosis partly becomes the salt of crystallization through the evaporation of political system and gets rid of, another part becomes the comdenstion water, and the comdenstion water flows into the product water tank storage that the bottom set up. The clean water from the medium pressure reverse osmosis is fed to a reverse osmosis system for further treatment.

And 5: and the electrodialysis system is used for producing primary saline water from the nanofiltration system, performing electrodialysis concentration on the primary saline water, then enabling the strong brine to flow into the bipolar membrane electrodialysis system for further treatment, enabling fresh water to flow into the high-pressure osmosis system for retreatment, enabling the high-pressure reverse osmosis produced water to flow into the low-pressure reverse osmosis system again for storage, and enabling the low-pressure reverse osmosis concentrated water to flow into the clean water tank for retreatment.

Step 6: and in the bipolar membrane electrodialysis system, concentrated brine enters the bipolar membrane electrodialysis treatment through the electrodialysis system, and finally the obtained products are hydrochloric acid and sodium hydroxide.

The invention adopts a zero-emission and recycling process. Purifying waste salt obtained from graphite wastewater to prepare acid and alkali. The solid waste and hazardous waste of the graphite wastewater treatment can not be treated, the investment of environmental protection cost is large, and simultaneously, the waste of salt resources is caused. The invention aims at the deep comprehensive utilization of the high-salinity and high-acidity wastewater generated in the processing and production process of the graphite ore, so that the high-salinity and high-acidity wastewater is converted into high-added-value sodium hydroxide and hydrochloric acid. No other by-products and wastes are generated, and the resource recycling and zero emission are realized. Compared with the treatment mode of waste salt generated by MVR evaporation, the method has great progress.

Drawings

FIG. 1 is a flow chart of the prior art.

FIG. 2 is a process flow diagram of the present invention.

Detailed Description

The invention will be described in detail below with reference to the following figures: as shown in fig. 2, a graphite wastewater treatment device comprises a pretreatment system 1, anultrafiltration system 2, asoftening system 3, ananofiltration system 4, an electrodialysis system 5, areverse osmosis system 6 and anevaporation system 7 which are connected in sequence, wherein the pretreatment system comprises araw water tank 8, aprimary reaction tank 9, asecondary reaction tank 10, a plate-and-frame filter press 11 and asedimentation tank 12 which are connected in sequence, a bottomsludge return pipeline 13 leading to the primary reaction tank is arranged at the bottom of thesedimentation tank 12, and clean water enters a subsequent pipeline; clear water treated by the pretreatment system 1 enters theultrafiltration system 2, backwash water and concentrated solution in theultrafiltration system 2 flow to theprimary reaction tank 9 through areturn pipeline 14, and produced water enters a subsequent pipeline; thesoftening system 3 is provided with a regenerationliquid return pipeline 15 leading to the primary reaction tank, and softened soft water enters a subsequent pipeline; thenanofiltration system 4 realizes the separation of divalent ions, wherein monovalent brine enters the electrodialysis system 5 through a pipeline, and divalent brine enters thereverse osmosis system 6 through a pipeline; the electrodialysis system 5 is composed of a homogeneousmembrane electrodialysis cell 16 and a bipolarmembrane electrodialysis cell 17 respectively, the electrodialysis system 5 is used for concentrating primary saline water, the bipolarmembrane electrodialysis system 17 is used for preparing acid and alkali from electrodialysis concentrated saline water, fresh water of the electrodialysis system 5 enters thereverse osmosis system 6 for concentration, produced water is recycled, and concentrated water is returned to the electrodialysis system 5 for desalination treatment; thereverse osmosis system 6 is used for concentrating divalent salt water and recycling fresh water.

And a high-pressurereverse osmosis system 18 is arranged at one side of thenanofiltration system 4, concentrated water is led into theevaporation system 7 by thereverse osmosis system 18 to be evaporated to obtain crystallized salt and condensed water, the crystallized salt is discharged outwards, the condensed water flows into awater production tank 19 through apipeline 20, and the produced water is led into thereverse osmosis system 6 for advanced treatment through apipeline 21.

The method for treating the wastewater by the graphite wastewater treatment device comprises the following steps:

step 1, pretreatment, namely flowing water in a raw water tank into a first-stage reaction tank, adding calcium oxide between the first-stage reaction tank and a second-stage reaction tank, reacting in the second-stage reaction tank, extruding large calcium fluoride sludge through a plate-and-frame filter press, conveying away, adding sodium carbonate into the remaining aqueous solution, flowing into a sedimentation tank for sedimentation, and refluxing settled bottom mud into the first-stage reaction tank for circular reaction;

step 2, ultrafiltration filtration: adding acid into part of the solution in the sedimentation tank to adjust the pH value, introducing the solution into a super filter tank to carry out ultrafiltration reaction, refluxing part of concentrated solution after the reaction to a first-stage reaction tank for further reaction, and flowing the other part of the concentrated solution into a softening tank below the first-stage reaction tank.

Step 3, softening treatment: the produced water from the ultrafiltration system flows into a softening system, the softening system is softened by resin, the resin is regenerated by acid and alkali after being adsorbed and saturated, and the regenerated liquid flows into a primary reaction tank for carrying out treatment reaction;

step 4, nanofiltration system: produce water from ultrafiltration system and carry out the separation of divalent salt again through the system of receiving straining, the second grade salt water flows into the middling pressure reverse osmosis pond through the pipeline and carries out reverse osmosis, and during the electrodialysis system of first order salt moisture inflow bottom, in the concentrated water of middling pressure reverse osmosis partly becomes the salt of crystallization through the evaporation of political system and gets rid of, another part becomes the comdenstion water, and the comdenstion water flows into the product water tank storage that the bottom set up. The clean water from the medium pressure reverse osmosis is fed to a reverse osmosis system for further treatment.

And 5: and the electrodialysis system is used for producing primary saline water from the nanofiltration system, performing electrodialysis concentration on the primary saline water, then enabling the strong brine to flow into the bipolar membrane electrodialysis system for further treatment, enabling fresh water to flow into the high-pressure osmosis system for retreatment, enabling the high-pressure reverse osmosis produced water to flow into the low-pressure reverse osmosis system again for storage, and enabling the low-pressure reverse osmosis concentrated water to flow into the clean water tank for retreatment.

Step 6: and in the bipolar membrane electrodialysis system, concentrated brine enters the bipolar membrane electrodialysis treatment through the electrodialysis system, and finally the obtained products are hydrochloric acid and sodium hydroxide.

The method comprises the steps of collecting the drained water in a raw water tank, homogenizing the water quality and the water quantity in the raw water tank, lifting the water to a primary reaction tank and a secondary reaction tank by a lifting water pump of the raw water tank, adding calcium oxide into the reaction tanks, removing calcium fluoride by a plate-and-frame filter press, adding soda ash, a coagulant and a coagulant aid into the supernatant, quickly mixing, automatically flowing to a sedimentation tank for sedimentation reaction, and recovering the bottom mud of the sedimentation tank to the primary reaction tank. The supernatant enters the membrane system.

Conveying the waste water to a sodium bed by a pump for softening again, and discharging the regenerated water of the sodium bed to an adjusting tank for circular treatment mainly for removing calcium ions, magnesium ions and other divalent ions which are easy to scale. And (3) conveying the effluent of the sodium bed to an NF system, removing divalent salt and the like, and then introducing monovalent salt NaCl into an electrodialysis system. The divalent salt enters an evaporation system after entering DTRO for concentration. And (5) recycling the condensed water. And (3) allowing the monovalent salt NaCl to enter an electrodialysis system, concentrating (mixing NF with produced water) to 14%, and allowing the monovalent salt NaCl to enter a bipolar membrane system to prepare acid and alkali. Desalting the electrodialytic fresh water to a reclaimed water reuse index by using a seawater desalting membrane and a reverse osmosis membrane.

The advantages of the invention are as follows:

1. the pretreatment of the invention is the same as the original pretreatment. Collecting the drained water in a raw water tank, homogenizing the water quality and the water quantity in the raw water tank, lifting the water to a primary reaction tank and a secondary reaction tank by a lifting water pump of the raw water tank, adding calcium oxide into the reaction tanks, and removing calcium fluoride by a plate-and-frame filter press.

2. The invention adds the process of converting calcium chloride into sodium chloride, namely, the pretreated supernatant is added with sodium carbonate, and the calcium salt is converted into sodium salt after the reaction is finished; and (4) softening the reacted wild in a sodium bed again, converting the residual calcium ions and magnesium ions into sodium ions, and concentrating the converted NaCL solution in an electrodialysis system.

3. The invention adopts electrodialysis technology to replace a concentrated disc tube type (DTRO) reverse osmosis device in the original process, and the concentration of salt is increased to 200g/L from 90 g/L.

4. The invention adopts a bipolar membrane technology to replace an MVR system, and adopts the bipolar membrane technology to prepare hydrochloric acid and sodium hydroxide from sodium chloride; the sodium chloride is recycled, and the problem of salt treatment is thoroughly solved. The prepared hydrochloric acid and sodium hydroxide can be returned to the graphite processing technology, and the overall operation cost is reduced.

The invention can treat the waste water produced in the production process of industrial enterprises and recycle the treated waste water, and does not discharge waste water to the outside. The final produced water is completely recycled to enterprise users, so that the enterprise users can use the recycled water of the project to replace tap water in the production process, and the production cost can be greatly reduced. In addition, the wastewater is effectively treated and controlled to achieve zero emission of pollutants, the environmental quality can be obviously improved, the amount of precious water resources is protected, and the indirect economic benefit generated by the method is huge.

The strong brine separated by the electrodialysis device is subjected to electrodialysis by the bipolar membrane to generate hydrochloric acid and sodium hydroxide, and the bipolar membrane is not subjected to water dissociation to generate gas and byproducts, so that the voltage is lower, the energy consumption is lower compared with that of the traditional electrolysis method, and the energy is utilized to the maximum extent. According to the fact that a large amount of sodium hydroxide and hydrochloric acid are consumed in the production process of graphite, both the hydrochloric acid and sodium hydroxide generated by the bipolar membrane technology can be utilized, and great economic benefits are generated. The method solves the problem of waste salt, reduces the operating cost, reduces the environmental pollution, and conforms to the environmental protection concept of green production and clean production.

Claims (3)

1. A graphite wastewater treatment device comprises a pretreatment system (1), an ultrafiltration system (2), a softening system (3), a nanofiltration system (4), an electrodialysis system (5), a reverse osmosis system (6) and an evaporation system (7) which are sequentially connected, and is characterized in that the pretreatment system comprises a raw water tank (8), a primary reaction tank (9), a secondary reaction tank (10), a plate-and-frame filter press (11) and a sedimentation tank (12) which are sequentially connected, wherein a bottom sludge backflow pipeline (13) leading to the primary reaction tank is arranged at the bottom of the sedimentation tank (12), and clean water enters a subsequent pipeline; clear water enters the ultrafiltration system (2) after being treated by the pretreatment system (1), backwash water and concentrated solution in the ultrafiltration system (2) flow to the primary reaction tank (9) through a return pipeline (14), and produced water enters a subsequent pipeline; the softening system (3) is provided with a regeneration liquid return pipeline (15) leading to the primary reaction tank, and softened soft water enters a subsequent pipeline; the nanofiltration system (4) realizes the separation of divalent ions, wherein monovalent brine enters the electrodialysis system (5) through a pipeline, and divalent brine enters the reverse osmosis system (6) through a pipeline; the electrodialysis system (5) is composed of a homogeneous membrane electrodialysis cell (16) and a bipolar membrane electrodialysis cell (17), the electrodialysis system (5) is used for concentrating primary saline water, the bipolar membrane electrodialysis cell (17) is used for preparing acid and alkali from electrodialysis concentrated saline water, fresh water of the electrodialysis system (5) enters a reverse osmosis system (6) for concentration, produced water is recycled, and concentrated water is desalted again by the electrodialysis system (5); the reverse osmosis system (6) is used for concentrating divalent brine and recycling fresh water.

2. The graphite wastewater treatment device according to claim 1, characterized in that one side of the nanofiltration system (4) is provided with a high-pressure reverse osmosis system (18), the reverse osmosis system (18) leads concentrated water to an evaporation system (7) to obtain crystallized salt and condensed water through evaporation, the crystallized salt is discharged outwards, the condensed water flows to a water production tank (19) through a pipeline (20), and the produced water leads to the reverse osmosis system (6) through a pipeline (21) for advanced treatment.

3. A method for treating wastewater by the graphite wastewater treatment facility according to claim 1 or 2, characterized in that the method comprises:

step 1, pretreatment, namely flowing water in a raw water tank into a first-stage reaction tank, adding calcium oxide between the first-stage reaction tank and a second-stage reaction tank, reacting in the second-stage reaction tank, extruding large calcium fluoride sludge through a plate-and-frame filter press, conveying away, adding sodium carbonate into the remaining aqueous solution, flowing into a sedimentation tank for sedimentation, and refluxing settled bottom mud into the first-stage reaction tank for circular reaction;

step 2, ultrafiltration filtration: adding acid into part of the solution in the sedimentation tank to adjust the pH value, introducing the solution into a super filter tank to carry out ultrafiltration reaction, refluxing part of concentrated solution after the reaction into a first-stage reaction tank for further reaction, and flowing the other part of the concentrated solution into a softening tank below the first-stage reaction tank;

step 3, softening treatment: the produced water from the ultrafiltration system flows into a softening system, the softening system is softened by resin, the resin is regenerated by acid and alkali after being adsorbed and saturated, and the regenerated liquid flows into a primary reaction tank for carrying out treatment reaction;

step 4, nanofiltration system: the water produced by the ultrafiltration system is subjected to secondary salt separation by the nanofiltration system, secondary salt water flows into a medium-pressure reverse osmosis pool through a pipeline for reverse osmosis, primary salt water flows into an electrodialysis system at the bottom, part of concentrated water subjected to medium-pressure reverse osmosis is evaporated by a political system to be changed into crystallized salt to be discharged, the other part of concentrated water is changed into condensed water, and the condensed water flows into a water production tank arranged at the bottom for storage;

the clean water after medium-pressure reverse osmosis flows into a reverse osmosis system for further treatment;

and 5: the electrodialysis system is used for producing primary saline water from the nanofiltration system, performing electrodialysis concentration on the primary saline water, then enabling the strong brine to flow into the bipolar membrane electrodialysis system for further treatment, enabling fresh water to flow into the high-pressure osmosis system for retreatment, enabling the high-pressure reverse osmosis produced water to flow into the low-pressure reverse osmosis system again for storage, and enabling the low-pressure reverse osmosis concentrated water to flow into the clear water tank for retreatment;

step 6: and in the bipolar membrane electrodialysis system, concentrated brine enters the bipolar membrane electrodialysis treatment through the electrodialysis system, and finally the obtained products are hydrochloric acid and sodium hydroxide.

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