WO2023036053A1

WO2023036053A1 - Cooperative treatment method and treatment system for high-salt solid waste ash and acidic wastewater of steel plant

Info

Publication number: WO2023036053A1
Application number: PCT/CN2022/116649
Authority: WO
Inventors: 叶恒棣; 颜旭; 杨本涛; 魏进超; 柴立元; 刘彦廷; 冯哲愚
Original assignee: 中冶长天国际工程有限责任公司; 中南大学
Priority date: 2021-09-07
Filing date: 2022-09-02
Publication date: 2023-03-16
Also published as: CN114702188A; CN114702188B

Abstract

Disclosed are a cooperative treatment method and a treatment system for high-salt solid waste ash and acidic wastewater of a steel plant. High-purity potassium chloride is generated by means of the high-salt solid waste ash produced by steel enterprises. Meanwhile, on the basis of the characteristics of the high content of heavy metals such as thallium, the high ammonia-nitrogen concentration and the high sulfate concentration in the conventional high-salt solid waste ash washing wastewater, and in combination with the characteristics that the wastewater of the steel plant contains a large amount of sulfite ions (flue gas washing wastewater) or iron ions (cold rolling rinsing wastewater) and has a low acidity, the purposes of cooperative treatment and recycling of the high-salt solid waste ash and acidic wastewater of the steel plant are achieved based on the existing high-salt solid waste ash washing and wastewater recycling processes by means of the synergistic effects of the acidic wastewater sectional supply for ash washing, sulfur and ammonia-nitrogen removal, the advanced oxidation of thallium, COD and ammonia-nitrogen by iron-carbon micro-electrolysis, and countercurrent evaporation for potassium and sodium separation, thereby greatly improving the quality of the recycled potassium and sodium salts. In addition, the technical solution provided by the present invention further has the advantages of simple process conditions, low energy consumption, no wastewater discharge, etc.

Description

A method and system for co-processing high-salt solid waste ash and acid wastewater from iron and steel plants

technical field

The invention relates to solid waste and wastewater treatment in the iron and steel industry, in particular to a method and a treatment system for the collaborative treatment of high-salt solid waste ash and acid wastewater from iron and steel plants, and belongs to the technical field of collaborative resource treatment of solid waste ash and wastewater in the iron and steel industry.

Background technique

At present, for the high-salt solid waste ash produced by iron and steel plants (such as sintering electric field ash, blast furnace bag ash, rotary kiln surface cold ash, waste incineration fly ash, etc.), water washing is often used to remove alkali and chlorine metals, such as China Patent CN103435073A "Method for Producing Potassium Chloride Using Blast Furnace Gas Ash in Iron and Steel Enterprises" reports that tap water is used to leach blast furnace gas ash to greatly reduce potassium and chlorine in blast furnace gas ash, and the leaching solution is used to prepare potassium chloride and sodium chloride. Chinese patent CN101234766A "Method for Producing Potassium Chloride Using Sintered Electrostatic Precipitator Ashes in Iron and Steel Enterprises" reports a method for leaching high-salt solid waste ash using a compound solution of tap water and SDD inhibitors, and the leaching rate of potassium and sodium can reach 95-99.5%. . After washing and leaching, the high-salt solid waste can be returned to high-temperature furnaces such as sintering, blast furnaces, and rotary kilns for further processing after dehydration. However, in the process of washing and leaching high-salt solid waste, a large amount of high-salt leaching wastewater will be produced, which can be used to prepare potassium chloride and sodium chloride. Generally, high-salt wastewater is used for evaporation and crystallization of potassium and sodium salts after pretreatment to remove heavy metals and color. In the actual operation process, since the high-salt wastewater contains a large amount of sulfate (the concentration is generally around 2g/L), if it is not removed, it will eventually enter the potassium chloride, reducing the salt quality and causing the evaporation system to form potassium glauberite. And clogged. In addition, high-salt wastewater also contains pollutants such as thallium and ammonia nitrogen. However, if these pollutants are removed in depth, there will be a shortcoming of a long treatment process, which will cause a sharp increase in treatment costs.

There are many ways to remove sulfate radicals in wastewater, such as barium chloride method, nanofiltration method, and calcium oxide method for sulfuric acid removal. However, these methods have different disadvantages and are not suitable for the removal of pollutants in gray washing water. For example, the Chinese patent CN110342710A "High Chlorine and Low Sulfate Wastewater Treatment System and Technology thereof" introduces the method of precipitation and removal of sulfate by adding calcium chloride, and the sulfate can be reduced from 6000ppm to 2000ppm. However, this method cannot be applied to the above-mentioned gray washing water, because the concentration of sulfate radicals in the above gray washing water is generally 1500-3000 ppm, and this method cannot realize the deep removal of sulfate radicals in the gray washing water. In order to realize the deep removal of sulfate radicals, Chinese patent CN111592148A "A Process Method for Converting High-Saline Wastewater into NaOH Solution" reports the efficient removal of sulfate radicals by using calcium-aluminum compound salts under high alkaline conditions. However, when this method is used to remove sulfate radicals in gray washing water, the pH of the solution is too high, requiring a large amount of hydrochloric acid to be adjusted back, and at the same time, the formed particles are relatively fine and need to be removed by filtration.

The methods for removing ammonia nitrogen in wastewater include ammonia distillation, magnesium ammonium phosphate method, stripping method, etc. Among them, ammonia distillation and stripping require the construction of additional devices and the treatment of recovered ammonia gas, and the investment and operation costs are relatively high. However, the magnesium ammonium phosphate method needs to introduce phosphate radicals and magnesium ions, which is difficult to operate and has the disadvantages of high operating costs.

For the removal of thallium in high-salt wastewater, there are mainly sodium sulfide precipitation, oxidation precipitation and electrochemical precipitation, among which oxidation precipitation is the most commonly used method. For example, Chinese patent CN106977013A discloses a purification treatment method and its application of high-chloride thallium-containing wastewater. After oxidizing Tl(I), the pretreatment of Tl(III) is carried out by ion exchange resin, and then the Tl(III) is treated by sodium sulfide. (III) Perform deep removal. However, since Tl(III) will form stable [TlCl4 ^- ] with chlorine in high-salt wastewater, and because the complex is relatively stable, it is difficult to remove it completely by precipitation.

Contents of the invention

Aiming at the deficiencies of the prior art, the present invention provides a method and a treatment system for the coordinated treatment of high-salt solid waste ash and acid wastewater from iron and steel plants (flue gas washing wastewater, cold rolling rinsing wastewater, etc.), which can utilize the sintering process of iron and steel enterprises to produce High-purity potassium chloride is produced from waste water and high-salt solid waste ash, and at the same time, it prevents alkali metals and chlorine from entering high-temperature furnaces such as sintering, blast furnaces, and rotary kilns, which cause equipment corrosion and kiln knotting. At the same time, based on the characteristics of high-salt solid waste ash washing wastewater with high heavy metals such as thallium, high ammonia nitrogen concentration, and high sulfate concentration, combined with the iron and steel plant wastewater containing a large amount of sulfite ions (flue gas washing wastewater) or iron ions (cold rolling rinse wastewater) And the characteristics of low acidity, on the basis of the existing high-salt solid waste ash washing and waste water recycling process, the steel plant acid waste water is used to supply ash washing, sulfur removal and deammonization nitrogen, iron-carbon micro-electrolysis deep oxide thallium and COD, The synergistic effect of countercurrent evaporation to separate potassium and sodium achieves the purpose of synergistic treatment and resource utilization of high-salt solid waste ash and acid wastewater from iron and steel plants, and greatly improves the quality of recovered potassium and sodium salts. At the same time, the technical solution provided by the invention also has the advantages of simple process conditions, low energy consumption, no waste water discharge, and the like.

In order to achieve the above object, the technical scheme adopted in the present invention is specifically as follows:

According to the first embodiment of the present invention, a method for the coordinated treatment of high-salt solid waste ash and acid wastewater from iron and steel plants is provided.

A method for co-processing high-salt solid waste ash and acid wastewater from iron and steel plants, the method comprising the following steps:

1) Ash washing treatment: Mix industrial water and part of flue gas washing wastewater to obtain acidic mixed water, and use the acidic mixed water to wash high-salt solid waste ash, and obtain filter cake and ash washing wastewater after solid-liquid separation, filter cake For external disposal, the ash washing wastewater is mixed with the remaining flue gas washing wastewater to obtain mixed wastewater for next-level treatment.

Alternatively, use part of the cold-rolling and rinsing wastewater to wash the high-salt solid waste ash, obtain filter cake and ash-washing wastewater after solid-liquid separation, and transport the filter cake for disposal. The ash-washing wastewater is mixed with the remaining cold-rolling and rinsing wastewater and heated for precipitation Reaction, after the reaction is completed, the solid-liquid separation obtains the mixed wastewater and the slag phase, the slag phase is transported outside for disposal, and the mixed wastewater is processed in the next stage.

2) Micro-electrolysis treatment: the mixed wastewater obtained in step 1) is subjected to iron-carbon micro-electrolysis treatment.

3) Advanced pretreatment of wastewater: add mixed chemicals to the mixed wastewater after micro-electrolysis treatment, adjust the mixed wastewater to alkaline and carry out heavy and hard precipitation reaction on the mixed wastewater, and obtain high-salt wastewater and residue after solid-liquid separation Sinotrans disposal, high-salt wastewater for next-level treatment.

4) Countercurrent evaporation treatment: heating high-salt wastewater, performing concentration and crystallization, and obtaining sodium chloride and filtrate I after solid-liquid separation. The filtrate I is cooled and crystallized, and potassium chloride and filtrate II are obtained after solid-liquid separation.

Preferably, the method also includes:

5) Circulating evaporation treatment: the filtrate II produced in step 4) is mixed with the high-salt wastewater produced in step 3), and then the countercurrent evaporation treatment is continued. Or, the filtrate II produced in step 4) is returned to step 1) to participate in washing the mixture with water.

Preferably, in step 1), the flue gas washing wastewater is acidic flue gas washing wastewater, preferably the flue gas washing wastewater produced by desorption gas washing by activated carbon method.

Preferably, in step 1), the cold-rolling rinsing wastewater is wastewater containing _FeCl3 and HCl produced in the rinsing section of the cold-rolled strip pickling process, preferably pH<2.

Preferably, in step 1), the high-salt solid waste ash includes one or more of sintered electric field ash, blast furnace bag ash, rotary kiln surface cooling ash, and waste incineration fly ash, preferably sintered electric field ash.

As preferably, in step 1), the water-cement mass ratio of acidic mixed water and high-salt solid waste ash or the water-cement mass ratio of cold rolling rinsing wastewater and high-salt solid waste ash is 1-6:1, preferably 2- 4:1.

Preferably, in step 1), the amount of waste gas washing or cold rolling rinsing wastewater added is such that the pH of the mixed wastewater is 2-4, preferably 2.5-3.5.

Preferably, in step 1), the heating for precipitation reaction is heating to 80-100°C for precipitation reaction for 1-8h, preferably heating to 85-95°C for precipitation reaction for 2-5h.

As preferably, in step 1), before heating to carry out the precipitation reaction, the molar ratio of sulfate ion, ammonia nitrogen, and iron ion in the wastewater is 0.4-0.8:0.2-0.5 by adding soluble iron salt (such as FeCl ₃ ) :1, preferably 0.5-0.7:0.25-0.4:1.

Preferably, in step 2), before the mixed wastewater is subjected to iron-carbon micro-electrolysis, it is necessary to use alkali to adjust its pH to 3-5, preferably 3.5-4. The duration of the iron-carbon micro-electrolysis treatment is not less than 20 minutes, preferably 30-60 minutes. During the iron-carbon micro-electrolysis process, regular aeration and recoil are required.

Preferably, in step 2), the alkali is sodium hydroxide and/or potassium hydroxide.

As preferably, in step 3), the mixed agent is sodium hydroxide and/or potassium hydroxide, sodium carbonate and/or potassium carbonate, sodium sulfide and/or potassium sulfate, recapture agent (preferably xanthate Class recapture agent or dithiocarbamate recapture agent) together. Wherein: the addition amount of sodium hydroxide and/or potassium hydroxide is such that the pH of the mixed wastewater is 7-9, preferably 7.5-8. The added amount of the sodium carbonate and/or potassium carbonate is 3-10g/L, preferably 4-8g/L. The added amount of the sodium sulfide and/or potassium sulfide is 1-7g/L, preferably 1.5-6g/L. The added amount of the recapture agent is 1-8g/L, preferably 2-5g/L.

Preferably, in step 3), the content ratio of potassium and sodium in the high-salt wastewater is not lower than 4, preferably not lower than 5.

Preferably, in step 3), the time for the mixed wastewater to undergo the weight removal and hard precipitation reaction is not less than 10 minutes, preferably 15-40 minutes.

Preferably, in step 4), the countercurrent evaporation is carried out using a multi-effect evaporator, and the number of stages of the multi-effect evaporator is 2-6, preferably 3-5. The heating high-salt wastewater is heating high-salt wastewater to 80-100°C, preferably 90-95°C. The liquid I is cooled by means of flash evaporation or heat exchange to below 60°C, preferably 20-55°C.

Preferably, the water washing in the ash washing treatment is a multi-stage water washing treatment, preferably a three-stage countercurrent water washing treatment. Specifically: Firstly, the high-salt solid waste ash is firstly washed with water, and dehydrated through a first-stage filter press to obtain a first-stage filtrate and a first-stage filter residue, and the first-stage filtrate is subjected to subsequent micro-electrolysis treatment. The first-stage filter residue enters the second-stage washing, and the water source of the second-stage washing is the third-stage filtrate. After the second-stage water washing, it is dehydrated through the second-stage filter press to obtain the second-stage filtrate and the second-stage filter residue. The second-stage filtrate is discharged to the first-stage washing for recycling. The secondary filter residue enters the tertiary water washing. The water source of the tertiary washing is the acidic mixed water mixed with industrial water and flue gas washing wastewater. To the secondary water washing cycle, the tertiary filter residue is discharged and shipped out for disposal.

According to the second embodiment of the present invention, a system for the coordinated treatment of high-salt solid waste ash and acid wastewater from iron and steel plants is provided.

A system for co-processing high-salt solid waste ash and acid wastewater from iron and steel plants. The system includes a countercurrent washing device, a regulating tank, an iron-carbon micro-electrolytic tank, a heavy and hard removing tank, and a countercurrent multi-effect evaporator. The waste water inlet pipe is connected with the water inlet of the countercurrent washing device. The water outlet of the countercurrent washing device communicates with the water inlet of the adjustment tank through the first pipeline. The outlet of the regulating pool is communicated with the water inlet of the iron-carbon micro-electrolytic cell through the second pipeline. The outlet of the iron-carbon micro-electrolytic cell is communicated with the water inlet of the heavy and hard removal cell through a third pipeline. The outlet of the heavy and hard removal pool is communicated with the water inlet of the countercurrent multi-effect evaporator through the fourth pipeline. The countercurrent water washing device is also provided with an ash inlet for high-salt solid waste ash.

As a preference, the waste water inlet pipe also branches off a waste water branch pipe to communicate with the water inlet of the regulating tank. At least one medicine feeding port is also arranged on the regulating pool. A heating unit, a first pH detector and a temperature detector are also arranged in the regulating pool. Preferably, the heating unit is an electric heating unit or a steam heating unit.

Preferably, at least one mixing and feeding port is provided on the heavy and hard removing pool. A second pH detector is arranged in the heavy and hard removing pool.

Preferably, the countercurrent multi-effect evaporator includes a heating unit, a cooling unit and an elutriation unit. The liquid outlet of the heating unit communicates with the liquid inlet of the cooling unit through the fifth pipeline. The liquid discharge port of the cooling unit is communicated with the water inlet of the heating unit through a circulation transfusion pipe. The heating unit is also provided with a sodium salt outlet, and the sodium salt outlet communicates with the sodium salt delivery device. The cooling unit is also provided with a potassium salt outlet, and the potassium salt outlet communicates with the elutriation unit through a potassium salt conveying device. The outlet of the elutriation unit is connected with the pure salt conveying device.

Preferably, the steam outlet of the countercurrent multi-effect evaporator communicates with the adjustment tank through a steam delivery pipeline.

In the prior art, in order to avoid problems such as alkali metals and chlorine elements in high-salt solid waste ash that would cause equipment corrosion and unfavorable conditions such as kiln knotting, water washing is often used to remove alkali and chlorine metals, and recycle Potassium sodium salt. However, due to the complex composition of high-salt solid waste ash, the composition of gray washing water is complex, such as containing a large amount of metal ions, ammonia nitrogen, sulfate radicals, etc. In this regard, metal ions and ammonia nitrogen are often removed by adjusting the washing water to be alkaline. However, studies have shown that [TlCl 4 - ] is easy to form [TlCl ₄ ^- ] in high-salt solid waste ash washing wastewater under alkaline conditions, because [TlCl ₄ ^- ] are relatively stable, and once formed, are difficult to handle with conventional removal processes. The potassium salt that causes recovery has more impurities, and the purity is relatively low, which affects its utilization. Generally, for high-salt solid waste ash washing wastewater with more potassium than sodium, potassium salts are usually precipitated first, and then sodium salts are precipitated. On the one hand, potassium salts are precipitated first, and impurities and pollutants are easily precipitated with the precipitation of potassium salts. On the other hand, the subsequent precipitation of sodium salt requires continuous heating, concentration and crystallization, which increases energy consumption. And if the sodium salt is separated out first, because the content of potassium is more than sodium, the potassium salt will be separated out first, which reduces the quality of the sodium salt and the output of the potassium salt.

In the present invention, the technical process is as follows: first, use acidic mixed water (composed of part of the flue gas washing wastewater mixed with industrial water) or use part of the cold rolling rinsing wastewater to perform a three-stage countercurrent washing process for dechlorination of high-salt solid waste ash . The filter cake obtained after water washing is carried out for external disposal, and the ash washing wastewater obtained after water washing is mixed with the remaining part of flue gas washing wastewater or cold rolling rinsing wastewater so that the pH value of the mixed wastewater is 2-4 (preferably 2.5-3.5) At the same time, also by adding soluble iron salt (preferably FeCl ₃ ) to adjust the mol ratio of sulfate ion, ammonia nitrogen, iron ion in the mixed wastewater to be 0.4-0.8:0.2-0.5:1 (preferably 0.5-0.7:0.25 -0.4:1), and heat the mixed wastewater to 80-100°C (preferably 85-95°C) for a reaction time of 1-8h (preferably 2-5h) to remove ammonia nitrogen, sulfate, etc. in the mixed wastewater. Then add alkali (sodium hydroxide or potassium hydroxide) to the mixed wastewater to adjust the pH between 3-4, and then enter the iron-carbon micro-electrolysis reactor for micro-electrolysis reaction, and the iron-carbon micro-electrolysis reactor is regularly exposed Gas recoil. Since Tl ³⁺ is easier to remove than Tl ⁺ , in general, it can be pretreated by oxidation. Iron-carbon micro-electrolysis has the effect of synergistic weight removal and oxidation. After iron-carbon micro-electrolysis, Tl can be changed into a form that is easier to remove. At the same time, a large number of metal ions in the gray washing water will be replaced by iron to achieve removal, and a large amount of ferrous and ferric iron will be produced in the solution. In addition, iron carbon is beneficial to the efficient removal of fluoride ions in wastewater. Add mixed reagents (such as adding sodium hydroxide, sodium carbonate, sodium sulfide, and recapture agent in sequence to the wastewater after iron-carbon micro-electrolysis. The added amount of sodium hydroxide is mainly to adjust the pH of the solution to 7~ 10 (preferably 7-9), sodium carbonate, sodium sulfide, recapture agent, etc. are to carry out the heavy removal and hard precipitation reaction of wastewater, and the heavy metal ions and calcium and magnesium in the water are precipitated and separated), during this process Realize the deep removal of ammonia nitrogen, calcium magnesium, and heavy metals. The treated wastewater is filtered through a filter press together with the sediment. The filter residue is heavy metal sludge, which is transported abroad for disposal. The filtrate is high-salt wastewater. After the high-salt wastewater is homogenized, it is transported into the multi-effect evaporator. The multi-effect evaporator adopts a counter-current design, that is, the high-salt solution passes through "multi-effect reactor → second-effect reactor → first-effect reactor" in sequence, and the solution temperature rises from normal temperature to 95-100°C. After evaporation, the sodium salt is precipitated after reaching the saturated precipitation point of sodium salt, and the sodium salt can be recovered by centrifugation, and the mother liquor obtained by centrifugation is returned to the first-effect evaporator for circulation and concentration. After concentrating to the saturated precipitation point of potassium salt, lower the temperature and cool down, lower the solution temperature to below 60°C to precipitate potassium salt, and realize the recovery of potassium salt through centrifugal separation, and return the mother liquor obtained by centrifugal separation to the multi-effect evaporator for circulation and concentration. Further, the precipitated potassium chloride solid can also be entered into an elutriation device, washed with a saturated potassium chloride solution to realize further purification of potassium chloride, and high-purity potassium chloride can be obtained after centrifugation.

In the present invention, since the high-salt solid waste ash is high-potassium and low-sodium ash, the ratio of potassium to sodium in its conventional washing solution is generally greater than 4 (preferably greater than 5). According to the principle of potassium and sodium variable temperature salt separation, it is suitable for downstream evaporation, that is, through variable temperature evaporation to separate potassium and sodium salt phase diagram analysis, after the high potassium and low sodium solution is concentrated by evaporation, potassium salt will inevitably be precipitated first, so for high salt solid The salt separation method of waste ash washing water is generally downstream evaporation. That is, the solution is a process of gradually cooling down during the evaporation process. At the multi-effect outlet, potassium salts are discharged first. This evaporation method will lead to the precipitation of pollutants along with the precipitation of potassium, which will reduce the quality of potassium. At the same time, the subsequent precipitation of sodium salts requires two-stage evaporation, which increases investment and energy consumption. Therefore, the present invention introduces flue gas washing wastewater (containing sodium) and mixes it with industrial water as high-salt solid waste ash washing water, so that the potassium-sodium content ratio in the ash washing wastewater is close to 1:1, or the present invention introduces acid Cold rolling and rinsing wastewater can make the ratio of potassium and sodium in ash washing wastewater close to 2:1. Under these two conditions, according to phase diagram simulation and experimental verification, it is suitable for countercurrent evaporation, that is, after concentration, sodium is preferentially separated Salt, the evaporation process can be adjusted to countercurrent evaporation, that is, at the outlet of the first effect, the sodium salt is discharged first. Then the potassium salt is precipitated by cooling down. This evaporation method makes the residual pollutants precipitate with the precipitation of sodium (because the countercurrent evaporation only undergoes a period of concentration, the pollutants mainly enter the sodium salt), and will not enter the potassium salt. It is beneficial to improve the quality of potassium. At the same time, the whole evaporation only uses one-stage evaporation system, which can be applied to different evaporation volume changes, has stronger applicability to raw materials, and has lower investment.

In the present invention, the flue gas washing wastewater includes suspended solids, metal ions, ammonia nitrogen, and fluorine and chlorine. The metal ions include one or more of sodium, iron, copper, lead, calcium, zinc, cadmium, cobalt, nickel and aluminum. Firstly, the industrial water and part of the acidic flue gas washing wastewater are mixed, and the mixed water is made acidic (for example, the pH is 1-3). Generally, [TlCl ₄ - ] is easy to form [TlCl 4 ^- ] under alkaline conditions in high-salt wastewater. Since [TlCl ₄ ^- ] is relatively stable, once it is formed, it is difficult to use conventional removal techniques. Due to the strong acidity of flue gas washing wastewater, when using it for ash washing, on the one hand, it can reduce the solution of ash washing water and make the ash washing water acidic, thereby preventing the formation of stable [TlCl ₄ ^- ]. On the other hand, since the flue gas washing wastewater contains thiosulfate, its addition will facilitate the removal of thallium. So as to realize the source suppression of thallium. Studies have shown that the thallium content in the ash washing water is about 30 mg/L when the ash is washed with conventional industrial water. When the acidic washing wastewater is introduced, the thallium content in the gray washing water can be reduced to about 1mg/L. That is to say, the present invention uses acidic flue gas washing wastewater to co-process high-salt solid waste ash. On the one hand, it realizes the adjustment of potassium-sodium ratio close to 1:1, realizes countercurrent evaporation, improves the quality of potassium salt, and on the other hand reduces thallium at the source Dissolution further ensures the purity of potassium salt and improves the value of potassium salt.

In the present invention, the cold-rolling rinsing waste water is the waste water containing FeCl _and HCl produced in the rinsing section of the cold-rolled strip pickling process, and generally its pH<2.5 (preferably pH<2) is acidic. Based on the characteristics of heavy metals such as thallium in high-salt solid waste ash washing wastewater, high ammonia nitrogen concentration, and sulfate radical concentration (the ammonia nitrogen concentration in the gray washing water is generally 1000-4000mg/L, and the sulfate radical concentration is generally 500-3000mg/L), Combined with the characteristics of a large amount of ferric iron and low acidity in cold rolling rinse wastewater, considering that iron and sulfate radicals will react with potassium, sodium, and ammonia nitrogen to form jarosite, jarosite, and jarosite. Therefore, the wastewater can be heated (the heat source can be electric heating or the steam waste heat of the follow-up evaporation system) to 80-100°C to realize the removal of ammonia nitrogen and sulfate radicals in the wastewater. Secondly, the cold-rolling rinsing wastewater is used as the high-salt solid waste ash washing water, and the acidity of the cold-rolling rinsing wastewater is used to realize the control of ash washing wastewater. Because the acidic cold-rolling rinsing wastewater has strong acidity, when using it for ash washing , on the one hand, it can reduce the solution of gray washing water and make gray washing water acidic, thereby preventing the formation of stable [TlCl4 ^- ]. When the cold rolling rinse wastewater is introduced, the thallium content in the gray washing water can be reduced to about 5mg/L. Realized the reduction of thallium dissolution from the source. On the other hand, studies have shown that when the concentration of chloride ions in water is not higher than 15000mg/L, it will not cause chlorine enrichment in solid waste after washing. Therefore, the deep removal of chlorine in high-salt solid waste ash can be achieved by completely replacing industrial water with cold-rolling rinse wastewater. Played the effect of treating waste with waste.

In the present invention, impurities are also removed by iron-carbon micro-electrolysis. Since Tl ³⁺ is easier to remove than Tl ⁺ , generally speaking, pretreatment can be carried out by oxidation. Iron-carbon micro-electrolysis has the effect of synergistic weight removal and oxidation. After passing through iron-carbon, Tl can be changed into a form that is easier to remove. At the same time, a large number of metal ions in the gray washing water will be replaced by iron, and then removed, and a large amount of ferrous and ferric iron will be produced in the solution. In addition, iron-carbon is also conducive to the efficient removal of fluoride ions in wastewater. Further, since acidic flue gas washing wastewater also contains sulfite, iron carbon will release ferrous iron. Use alkali (such as sodium hydroxide) to adjust the ash washing wastewater to weak alkalinity. When the solution is adjusted to weak alkalinity, ammonia nitrogen will react rapidly with sulfite and ferrous to form ammonium ferrous sulfite precipitation, so as to realize the reduction of ammonia nitrogen. Deep removal. At the same time, under weak alkaline conditions, the removal of ferric iron and some calcium and magnesium ions can be realized. The purpose of adding sodium carbonate is to remove calcium and magnesium. The purpose of adding sodium sulfide and heavy catcher is to achieve deep removal of trace heavy metals.

In the present invention, the washing of high-salt solid waste ash is multi-stage washing, generally three-stage counter-current washing, and the three-stage counter-current washing process is that after the high-salt solid waste ash passes through one-stage water washing, and then passes through one-stage pressure filtration Dehydration, the filtrate is discharged into the subsequent wastewater resource treatment system (that is, directly into the iron-carbon micro-electrolysis), and the filter residue enters the secondary water washing. The water source for the second-stage washing is the water produced by the third-stage filter press. After the second-stage water washing, it is dehydrated by the second-stage filter press. The filtrate is discharged to the first-stage water wash for recycling, and the filter residue enters the third-stage water wash. The water source of the third-stage washing is a mixed solution of industrial water and condensed water recovered by evaporation. After the third-stage washing, it is dehydrated by a third-stage filter press, and the filtrate is discharged to the second-stage washing for recycling. Furthermore, the mother liquor after the potassium salt is precipitated by the multi-effect countercurrent evaporator is returned to the multi-effect countercurrent evaporator for circulation and concentration or returned to the water washing process to participate in water washing, realizing zero discharge of waste water.

In the system for co-processing high-salt solid waste ash and acid wastewater from iron and steel plants of the present invention, when the flue gas washing wastewater is used as the ash washing water for the high-salt solid waste ash, the regulating tank is only used as the ash washing wastewater and the remaining flue gas washing Wastewater is mixed, and the pH place of mixed wastewater is adjusted; when cold-rolling rinsing wastewater is used as gray washing water for high-salt solid waste ash, the above-mentioned adjustment tank can also be used as a place for adding soluble iron salts (such as FeCl ₃ ) and Heating the place where the precipitation reaction takes place.

Compared with the prior art, the beneficial technical effects of the present invention are as follows:

1: The present invention aims at the respective characteristics of high-salt solid waste ash and acid wastewater from iron and steel plants (flue gas washing wastewater or cold rolling rinsing wastewater), and carries out collaborative resource disposal of waste ash and wastewater. On the one hand, the waste water is washed by acidic flue gas Or acidic cold-rolling rinsing wastewater inhibits the leaching of thallium in high-salt solid waste ash, reduces the content of thallium in ash washing wastewater from the source, and improves the quality of subsequent potassium salts; secondly, the sodium contained in acidic flue gas washing wastewater is used, The ratio of potassium and sodium content in ash washing wastewater is close to 1:1, realizing multi-effect countercurrent evaporation, further improving the quality of potassium salt, and improving the reuse value of potassium salt; Ferric iron can realize the removal of ammonia nitrogen and sulfate radicals in wastewater; meanwhile, it also avoids the shortage of high potassium-sodium ratio in conventional ash washing wastewater, greatly improving the quality of potassium salts,

2: The present invention adopts iron-carbon micro-electrolysis and the method of adding mixed reagents, realizes synergistic thallium oxidation, deep removal of ammonia nitrogen, and weight removal at low cost, and greatly reduces the treatment process of ash washing wastewater, that is, prevents pollutants from polluting potassium salts. It can also greatly reduce energy consumption and improve production efficiency.

3: Compared with the traditional process, the solution of the present invention can avoid the introduction of other ions when directly removing impurities in the waste water by improving the evaporation mechanism and process route, and carry out low-cost extraction of ammonia nitrogen, thallium, heavy metals, etc. that affect the recovery of potassium salts. Removal, further improving the quality of the recovered potassium salt, can prevent pollutants from entering the potassium salt, thereby increasing the value of the potassium chloride product. At the same time, the invention also has the advantages of low cost and simple operation, does not increase equipment and energy consumption, rationally utilizes resources in the system, realizes digestion in the system, and greatly reduces the discharge of pollutants.

Description of drawings

Fig. 1 is a process flow chart of the co-processing method of high-salt solid waste ash and flue gas washing wastewater of the present invention.

Fig. 2 is a process flow diagram of the co-processing method of high-salt solid waste ash and cold-rolling rinsing wastewater of the present invention.

Fig. 3 is a schematic structural diagram of the system for the coordinated treatment of high-salt solid waste ash and acid wastewater from iron and steel plants according to the present invention.

Fig. 4 is a schematic structural diagram of the heating unit of the treatment system of the present invention being an electric heating device.

Reference numerals: 1: countercurrent washing device; 2: regulating pool; 201: dosing port; 202: heating unit; 203: first pH detector; 204: temperature detector; 3: iron-carbon micro-electrolytic cell; 4: 401: Mixing dosing port; 402: Second pH detector; 5: Countercurrent multi-effect evaporator; 501: Heating unit; 502: Cooling unit; 503: Elutriation unit; 504: Circulating infusion tube ;505: sodium salt delivery device; 506: potassium salt delivery device; 507: pure salt delivery device; L0: waste water inlet pipe; L01: waste water branch pipe; L1: first pipe; L2: second pipe; L3: third Pipeline; L4: fourth pipeline; L5: fifth pipeline; L6: steam delivery pipeline.

Detailed ways

The technical solution of the present invention is illustrated below, and the protection scope of the present invention includes but not limited to the following examples.

A system for co-processing high-salt solid waste ash and acid wastewater from iron and steel plants, the system includes a countercurrent washing device 1, a regulating tank 2, an iron-carbon micro-electrolytic tank 3, a heavy and hard removing tank 4, and a countercurrent multi-effect evaporator 5. The waste water inlet pipe L0 communicates with the water inlet of the countercurrent washing device 1 . The outlet of the countercurrent washing device 1 is connected with the water inlet of the regulating tank 2 through the first pipeline L1. The outlet of the regulating tank 2 is communicated with the water inlet of the iron-carbon micro-electrolytic cell 3 through the second pipeline L2. The outlet of the iron-carbon micro-electrolytic cell 3 is communicated with the water inlet of the deduplication and dehardness pool 4 through the third pipeline L3. The drain outlet of the heavy and hard removal pond 4 is communicated with the water inlet of the countercurrent multi-effect evaporator 5 by the fourth pipeline L4. The countercurrent water washing device 1 is also provided with an ash inlet 101 for high-salt solid waste ash.

Preferably, a waste water branch pipe L01 is also separated from the waste water inlet pipe L0 to communicate with the water inlet of the regulating tank 2 . The regulating pool 2 is also provided with at least one medicine feeding port 201 . A heating unit 202 , a first pH detector 203 and a temperature detector 204 are also arranged in the adjustment tank 2 . Preferably, the heating unit 202 is an electric heating unit or a steam heating unit.

As a preference, at least one mixing and feeding port 401 is provided on the heavy and hard removing pool 4 . A second pH detector 402 is arranged in the heavy and hard removing pool 4 .

Preferably, the countercurrent multi-effect evaporator 5 includes a heating unit 501 , a cooling unit 502 and an elutriation unit 503 . The liquid outlet of the heating unit 501 communicates with the liquid inlet of the cooling unit 502 through the fifth pipeline L5. The liquid outlet of the cooling unit 502 communicates with the water inlet of the heating unit 501 through a circulation infusion pipe 504 . The heating unit 501 is also provided with a sodium salt outlet, and the sodium salt outlet communicates with the sodium salt delivery device 505 . The cooling unit 502 is also provided with a potassium salt outlet, which communicates with the elutriation unit 503 through a potassium salt delivery device 506 . The outlet of the elutriation unit 503 is in communication with the pure salt delivery device 507 .

Preferably, the steam outlet of the countercurrent multi-effect evaporator 5 communicates with the regulating tank 2 through the steam delivery pipeline L6.

Example 1

As shown in Figure 1, a method for co-processing high-salt solid waste ash and flue gas washing wastewater, the method includes the following steps:

1) Water washing: Mix industrial water and flue gas washing wastewater to obtain acidic mixed water, and use the acidic mixed water to wash high-salt solid waste ash, obtain filter cake and ash washing wastewater after solid-liquid separation, and transport the filter cake for disposal , The ash washing wastewater is processed at the next level.

2) Micro-electrolysis treatment: Iron-carbon micro-electrolysis treatment is performed on the ash washing wastewater.

3) Advanced pretreatment of wastewater: add mixed chemicals to the ash-washing wastewater after micro-electrolysis treatment, adjust the ash-washing wastewater to alkaline, and carry out heavy and hard precipitation reaction on the ash-washing wastewater, and obtain high-salt wastewater after solid-liquid separation.

4) Countercurrent evaporation: heating high-salt wastewater, concentrating and crystallizing, and obtaining sodium chloride and filtrate I after solid-liquid separation. The filtrate I was cooled and crystallized, and potassium chloride and filtrate II were obtained after solid-liquid separation.

Example 2

5) Circulating evaporation: the filtrate II produced in step 4) is mixed with the high-salt wastewater produced in step 3), and then the countercurrent evaporation treatment is continued.

Example 3

5) Circulating evaporation: return the filtrate II produced in step 4) to step 1) to participate in washing the mixing material.

Example 4

As shown in Figure 2, a method for co-processing high-salt solid waste ash and cold-rolling rinsing wastewater, the method comprises the following steps:

1) Ash washing treatment: Part of the cold rolling rinsing wastewater is used to wash the high-salt solid waste ash, and the filter cake and ash washing wastewater are obtained after solid-liquid separation.

2) Desulfurization and ammonia nitrogen removal treatment: Mix ash washing wastewater with the remaining cold rolling rinsing wastewater to obtain mixed wastewater, and then heat the mixed solution to carry out precipitation reaction. After the reaction is completed, separate solid-liquid to obtain supernatant waste liquid and slag phase, The supernatant and waste liquid will be treated in the next stage.

3) Micro-electrolysis treatment: the supernatant waste liquid obtained in step 2) is subjected to iron-carbon micro-electrolysis treatment.

4) Advanced pretreatment of wastewater: add mixed chemicals to the supernatant waste liquid after micro-electrolysis treatment, adjust the supernatant waste liquid to alkaline and carry out heavy and hard precipitation reaction on the supernatant waste liquid, and obtain high Salt wastewater and residues, residues are shipped out for disposal, and high-salt wastewater is treated at the next level.

5) Countercurrent evaporation treatment: heating high-salt wastewater, performing concentration and crystallization, and obtaining sodium chloride and filtrate I after solid-liquid separation. The filtrate I was cooled and crystallized, and potassium chloride and filtrate II were obtained after solid-liquid separation.

Example 5

6) Circulating evaporation treatment: add the filtrate II produced in step 5) to the high-salt wastewater obtained in step 4), and continue to perform countercurrent evaporation treatment with the high-salt wastewater.

Example 6

As shown in Figure 3-4, a system for co-processing high-salt solid waste ash and acid wastewater from iron and steel plants, the system includes a countercurrent washing device 1, a regulating pool 2, an iron-carbon micro-electrolytic pool 3, and a de-duty and hard-removing pool 4 And countercurrent multi-effect evaporator 5. The waste water inlet pipe L0 communicates with the water inlet of the countercurrent washing device 1 . The outlet of the countercurrent washing device 1 is connected with the water inlet of the regulating tank 2 through the first pipeline L1. The outlet of the regulating tank 2 is communicated with the water inlet of the iron-carbon micro-electrolytic cell 3 through the second pipeline L2. The outlet of the iron-carbon micro-electrolytic cell 3 is communicated with the water inlet of the deduplication and dehardness pool 4 through the third pipeline L3. The water outlet of the heavy and hard removal pool 4 is communicated with the water inlet of the countercurrent multi-effect evaporator 5 through the fourth pipeline L4. The countercurrent water washing device 1 is also provided with an ash inlet 101 for high-salt solid waste ash.

Example 7

Repeat Example 6, except that the waste water inlet pipe L0 also separates a waste water branch pipe L01 to communicate with the water inlet of the regulating tank 2 . The regulating pool 2 is also provided with at least one medicine feeding port 201 . A heating unit 202 , a first pH detector 203 and a temperature detector 204 are also arranged in the adjustment tank 2 .

Example 8

Repeat Example 7, except that the heating unit 202 is an electric heating unit or a steam heating unit.

Example 9

Repeat Example 8, except that at least one mixing and feeding port 401 is provided on the heavy and hard removing pool 4 . A second pH detector 402 is arranged in the heavy and hard removing pool 4 .

Example 10

Repeat Example 9, except that the countercurrent multiple-effect evaporator 5 includes a heating unit 501 , a cooling unit 502 and an elutriation unit 503 . The liquid outlet of the heating unit 501 communicates with the liquid inlet of the cooling unit 502 through the fifth pipeline L5. The liquid outlet of the cooling unit 502 is communicated with the water inlet of the heating unit 501 through a circulating fluid delivery pipe 504 . The heating unit 501 is also provided with a sodium salt outlet, and the sodium salt outlet communicates with the sodium salt delivery device 505 . The cooling unit 502 is also provided with a potassium salt outlet, which communicates with the elutriation unit 503 through a potassium salt delivery device 506 . The outlet of the elutriation unit 503 is in communication with the pure salt delivery device 507 .

Example 11

Example 10 was repeated, except that the steam outlet of the countercurrent multiple-effect evaporator 5 communicated with the regulating tank 2 through the steam delivery pipeline L6.

Application Example 1

First, industrial water and activated carbon method flue gas washing wastewater are mixed to obtain acidic mixed water, and then 100kg of sintered power plant ash (potassium content is 24.8%, sodium content is 3.2%) is subjected to three-stage countercurrent washing with acidic mixed water, and obtained after pressure filtration. Filter cake and about 310L ash washing wastewater (wherein the ratio of potassium to sodium content is about 5.4), the filter cake is transported for disposal; then firstly add sodium hydroxide to the ash washing wastewater to adjust the pH of the ash washing wastewater to be 3 (activated carbon method flue gas washing The amount of wastewater and sodium hydroxide added makes the ratio of potassium and sodium in the ash-washing wastewater close to 1:1), and the adjusted ash-washing wastewater is passed into the iron-carbon micro-electrolysis reactor for 40 minutes, and the iron-carbon micro-electrolysis The reactor is regularly aerated and recoiled. After the micro-electrolysis treatment is completed, add sodium hydroxide again to adjust the pH of the ash-washing wastewater to be 8, then add 2kg sodium carbonate, 620g sodium sulfide, and 550g dithiocarbamate recapturing agent successively, and stir and mix for 30min; After filtration, high-salt wastewater is obtained. Heat high-salt wastewater to 95°C in a multi-effect countercurrent evaporator, concentrate and crystallize, and centrifuge to obtain sodium chloride and filtrate I. The filtrate I was cooled to below 60°C to precipitate crystals, and centrifuged to obtain crude potassium chloride and filtrate II. The filtrate II was returned to the countercurrent evaporation inlet for cyclic evaporation treatment; the crude potassium chloride was washed several times with saturated potassium chloride solution and centrifuged to obtain high-purity potassium chloride (purity 99.92%).

Application Example 2

First mix industrial water and activated carbon flue gas washing wastewater to obtain acidic mixed water, then use acidic mixed water to wash 120kg of blast furnace bag ash (potassium content is 29.4%, sodium content is 4.0%) with three-stage countercurrent washing, and press filter to obtain Filter cake and about 380L ash-washing wastewater (wherein the potassium-sodium content ratio is about 6.3), the filter cake is transported out for disposal; then firstly add sodium hydroxide to the ash-washing wastewater to adjust the pH of the ash-washing wastewater to be 4 (activated carbon method flue gas washing The amount of wastewater and sodium hydroxide added makes the ratio of potassium and sodium in the ash-washing wastewater close to 1:1), and the adjusted ash-washing wastewater is passed into the iron-carbon micro-electrolysis reactor for 40 minutes, and the iron-carbon micro-electrolysis The reactor is regularly aerated and recoiled. After the micro-electrolysis treatment is completed, add sodium hydroxide again to adjust the pH of the ash-washing wastewater to be 9, then add 3kg sodium carbonate, 665g sodium sulfide, and 450g dithiocarbamate recapture agent successively, and stir and mix for 30min; After filtration, high-salt wastewater is obtained. Heat the high-salt wastewater to 95°C in a multi-effect countercurrent evaporator, conduct concentration and crystallization, and centrifuge to obtain sodium chloride and filtrate I. The filtrate I was cooled to below 60°C to precipitate crystals, and centrifuged to obtain crude potassium chloride and filtrate II. The filtrate II was returned to the countercurrent evaporation inlet for circulation evaporation treatment; the crude potassium chloride was washed several times with a saturated potassium chloride solution and centrifuged to obtain high-purity potassium chloride (purity 99.90%).

Application Example 3

Use 380kg of cold-rolling rinsing wastewater (pH<2) to carry out three-stage countercurrent washing of 100kg of sintered electric field ash (potassium content is 24.8%, and sodium content is 3.2%). Ratio is about 5.1), the filter cake is transported for disposal; then continue to add cold rolling and rinsing wastewater (pH<2) to the gray washing wastewater to make the pH of the mixed wastewater 2-3; then add FeCl ₃ to the mixed wastewater to make the mixed wastewater The molar ratio of sulfate ions, ammonia nitrogen, and ferric ions in the wastewater is close to 2:1:3; then hot steam is introduced into the mixed wastewater to heat the mixed wastewater to 90°C for 3.5 hours, and after the reaction is completed, press filtration to obtain Supernatant liquid and slag phase, the slag phase is transported outside for disposal; use sodium hydroxide to adjust the pH of the supernatant to 3, then pass the supernatant into the iron-carbon micro-electrolysis reactor for 30 minutes, during which the iron-carbon micro-electrolysis The reactor is regularly aerated and recoiled. After the micro-electrolysis treatment is completed, add sodium hydroxide again to adjust the pH of the ash washing wastewater to be 8, and then add sodium carbonate (addition standard is 6g/L), sodium sulfide (addition standard is 4.8g/L), dithio Carbamate recapture agent (addition standard is 4.2g/L), stirring and mixing reaction for 30min; after the reaction is completed, press filter to obtain high-salt wastewater (the ratio of potassium to sodium in the high-salt wastewater is measured to be about 1.5:1). Heat high-salt wastewater to 95°C in a multi-effect countercurrent evaporator, concentrate and crystallize, and centrifuge to obtain sodium chloride and filtrate I. The filtrate I was cooled to below 60°C to precipitate crystals, and centrifuged to obtain crude potassium chloride and filtrate II. The filtrate II was returned to the countercurrent evaporation inlet for cyclic evaporation treatment; the crude potassium chloride was washed several times with saturated potassium chloride solution and centrifuged to obtain high-purity potassium chloride (purity 99.97%).

Application Example 4

Use 420kg of cold-rolling rinsing wastewater (pH<2) to carry out three-stage countercurrent washing of 100kg of blast furnace bag ash (potassium content is 29.4%, sodium content is 4.0%), and filter cake and ash washing wastewater (wherein potassium and sodium content are obtained after press filtration) ratio is about 5.7), the filter cake is transported out for disposal; then continue to add cold rolling and rinsing wastewater (pH<2) to the gray washing wastewater to make the pH of the mixed wastewater 2-3; then add FeCl ₃ to the mixed wastewater to make the mixed wastewater The molar ratio of sulfate ions, ammonia nitrogen, and ferric ions in the wastewater is close to 2:1:3; then hot steam is introduced into the mixed wastewater to heat the mixed wastewater to 90°C for 3.5 hours, and after the reaction is completed, press filtration to obtain Supernatant liquid and slag phase, the slag phase is transported outside for disposal; use sodium hydroxide to adjust the pH of the supernatant to 3, then pass the supernatant into the iron-carbon micro-electrolysis reactor for 30 minutes, during which the iron-carbon micro-electrolysis The reactor is regularly aerated and recoiled. After the micro-electrolysis treatment is completed, add sodium hydroxide again to adjust the pH of the ash washing wastewater to 8, and then add sodium carbonate (addition standard is 5.8g/L), sodium sulfide (addition standard is 4.0g/L), disulfide Carbamate-based recapture agent (addition standard is 4.0g/L), stirring and mixing reaction for 30min; after the reaction is completed, press filter to obtain high-salt wastewater (the ratio of potassium to sodium in the high-salt wastewater is measured to be about 1.8:1) . Heat high-salt wastewater to 95°C in a multi-effect countercurrent evaporator, concentrate and crystallize, and centrifuge to obtain sodium chloride and filtrate I. The filtrate I was cooled to below 60°C to precipitate crystals, and centrifuged to obtain crude potassium chloride and filtrate II. The filtrate II is returned to the countercurrent evaporation inlet for cyclic evaporation treatment; the crude potassium chloride is washed several times with saturated potassium chloride solution, and centrifuged to obtain high-purity potassium chloride (purity is 99.96%).

Claims

A method for co-processing high-salt solid waste ash and acid wastewater from iron and steel plants, characterized in that the method comprises the following steps:

1) Ash washing treatment: Mix industrial water and part of flue gas washing wastewater to obtain acidic mixed water, and use the acidic mixed water to wash high-salt solid waste ash, and obtain filter cake and ash washing wastewater after solid-liquid separation, filter cake Outbound disposal, the ash washing wastewater is mixed with the remaining flue gas washing wastewater to obtain the mixed wastewater and carry out the next level of treatment;

Alternatively, use part of the cold-rolling and rinsing wastewater to wash the high-salt solid waste ash, obtain filter cake and ash-washing wastewater after solid-liquid separation, and transport the filter cake for disposal. The ash-washing wastewater is mixed with the remaining cold-rolling and rinsing wastewater and heated for precipitation Reaction, after the reaction is completed, the solid-liquid separation obtains the mixed wastewater and slag phase, the slag phase is transported outside for disposal, and the mixed wastewater is processed in the next stage;

2) micro-electrolysis treatment: the mixed wastewater obtained in step 1) is subjected to iron-carbon micro-electrolysis treatment;

3) Advanced pretreatment of wastewater: add mixed chemicals to the mixed wastewater after micro-electrolysis treatment, adjust the mixed wastewater to alkaline and carry out heavy and hard precipitation reaction on the mixed wastewater, and obtain high-salt wastewater and residue after solid-liquid separation Outbound disposal, high-salt wastewater for next-level treatment;

4) Countercurrent evaporation treatment: heating the high-salt wastewater, concentrating and crystallizing, and obtaining sodium chloride and filtrate I after solid-liquid separation; cooling and crystallizing the filtrate I, and obtaining potassium chloride and filtrate II after solid-liquid separation.
The method according to claim 1, characterized in that: the method further comprises:

5) Circulating evaporation treatment: mix the filtrate II produced in step 4) with the high-salt wastewater produced in step 3), and then continue the countercurrent evaporation treatment; or, return the filtrate II produced in step 4) to step 1) to participate in washing and mixing material.
The method according to claim 1 or 2, characterized in that: in step 1), the flue gas washing wastewater is the acidic flue gas washing wastewater produced by activated carbon method analysis gas washing;

The cold-rolling rinsing wastewater is wastewater containing FeCl3 and HCl with a pH<2.5 produced in the rinsing section of the cold-rolled strip pickling process; and/or

The high-salt solid waste ash includes one or more of sintering electric field ash, blast furnace bag ash, rotary kiln surface cool ash, and waste incineration fly ash; and/or

The water-cement mass ratio of acidic mixed water and high-salt solid waste ash or the water-cement mass ratio of cold rolling rinsing wastewater and high-salt solid waste ash is 1-6:1.
The method according to claim 3, characterized in that: in step 1), the amount of flue gas washing wastewater or cold rolling rinsing wastewater is such that the pH value of the mixed wastewater is 2-4;

In step 1), the heating to carry out the precipitation reaction is heating to 80-100°C to carry out the precipitation reaction for 1-8h;

In step 1), before heating to carry out the precipitation reaction, the molar ratio of sulfate ions, ammonia nitrogen, and iron ions in the wastewater is 0.4-0.8:0.2-0.5:1 by adding soluble iron salts (such as FeCl 3 ); and / or

In step 2), it is necessary to use alkali to adjust its pH to 3-5 before the iron-carbon micro-electrolysis of the mixed wastewater; Rush; The alkali is sodium hydroxide and/or potassium hydroxide.
according to the method described in any one in claim 1-2,4, it is characterized in that: in step 3) in, described mixed agent is sodium hydroxide and/or potassium hydroxide, sodium carbonate and/or potassium carbonate, Sodium sulfide and/or potassium sulfate, recapture agent are jointly formed; Wherein: the add-on of sodium hydroxide and/or potassium hydroxide is to make the pH of mixed waste water be 7-9; The adding of described sodium carbonate and/or potassium carbonate Amount is 3-10g/L; The addition amount of described sodium sulfide and/or potassium sulfide is 1-7g/L; The addition amount of described recapture agent is 1-8g/L; And/or

The content ratio of potassium and sodium in the high-salt wastewater is not less than 5; and/or

The time for the mixed wastewater to carry out the weight removal and hard precipitation reaction is not less than 10 minutes.
According to the method described in any one of claims 1-2,4, it is characterized in that: in step 4), countercurrent evaporation adopts multi-effect evaporator to carry out, and the number of stages of multi-effect evaporator is 2-6; The heating of the high-salt wastewater is to heat the high-salt wastewater to 80-100°C; the cooling of the liquid I is to reduce the temperature to below 60°C by means of flash evaporation or heat exchange.
According to the method described in any one of claims 1-2, 4, it is characterized in that: the water washing in the ash washing treatment is a three-stage countercurrent water washing treatment; specifically: firstly, the high-salt solid waste ash is firstly washed with water, And through the dehydration of the first-level filter press, the first-level filtrate and the first-level filter residue are obtained, and the first-level filtrate is subjected to subsequent micro-electrolysis treatment; the first-level filter residue enters the second-level washing, and the water source for the second-level washing is the third-level filtrate. After the second-level washing, it passes through the second-level Press filtration and dehydration to obtain the secondary filtrate and secondary filter residue, the secondary filtrate is discharged to the primary water washing for recycling; the secondary filter residue enters the tertiary water washing, and the water source of the tertiary washing is acidic mixed water mixed with industrial water and flue gas washing wastewater, After the third-stage water washing, the third-stage filtrate and the third-stage filter residue are obtained through the third-stage filter press dehydration, and the third-stage filtrate is discharged to the second-stage water washing for recycling, and the third-stage filter residue is discharged for external transportation for disposal.
A system for the co-processing method of high-salt solid waste ash and steel plant acid wastewater as described in any one of claims 1-7, characterized in that: the system includes a countercurrent washing device (1), a regulating tank (2 ), an iron-carbon micro-electrolytic cell (3), a heavy and hard removal pool (4) and a countercurrent multi-effect evaporator (5); the waste water inlet pipe (L0) is connected with the water inlet of the countercurrent washing device (1); the countercurrent The outlet of the washing device (1) communicates with the water inlet of the regulating tank (2) through the first pipeline (L1); the outlet of the regulating tank (2) communicates with the iron-carbon micro-electrolytic cell (3) through the second pipeline (L2) ) is connected with the water inlet; the outlet of the iron-carbon micro-electrolytic cell (3) is connected with the water inlet of the deduplication and hardening pond (4) by the third pipeline (L3); the drainage of the deduplication and hardening pond (4) The mouth is connected with the water inlet of the countercurrent multi-effect evaporator (5) through the fourth pipeline (L4); the countercurrent water washing device (1) is also provided with a high-salt solid waste ash inlet (101).
The system according to claim 8, characterized in that: the waste water inlet pipe (L0) also separates a waste water branch pipe (L01) to communicate with the water inlet of the regulating pool (2); At least one dosing port (201) is provided; a heating unit (202), a first pH detector (203) and a temperature detector (204) are also arranged in the regulating tank (2); the heating unit (202) is electric heating unit or steam heating unit; and/or

The weight and hardness removing pool (4) is further provided with at least one mixed drug feeding port (401); the weight and hardness removing pool (4) is provided with a second pH detector (402).
The system according to claim 8 or 9, characterized in that: the countercurrent multi-effect evaporator (5) includes a heating unit (501), a cooling unit (502) and an elutriation unit (503); the heating unit (501) The liquid outlet of the cooling unit (502) is connected to the liquid inlet through the fifth pipe (L5); the liquid outlet of the cooling unit (502) is connected to the water inlet of the heating unit (501) through the circulation infusion pipe (504) pass; the heating unit (501) is also provided with a sodium salt outlet, and the sodium salt outlet is connected with the sodium salt delivery device (505); the cooling unit (502) is also provided with a potassium salt outlet, and the potassium salt outlet passes through the potassium salt delivery device (506) communicates with the elutriation unit (503); the outlet of the elutriation unit (503) communicates with the pure salt delivery device (507);

The steam outlet of the countercurrent multi-effect evaporator (5) communicates with the regulating tank (2) through a steam delivery pipeline (L6).