Comprehensive resource utilization system and method

Abstract

The invention provides a comprehensive resource utilization system and method, and belongs to the technical field of waste resource recovery, and the comprehensive resource utilization method comprises the following steps: firstly, carrying out water washing and filter pressing treatment on slurry obtained by mixing blast furnace gas condensate water and sintering machine head ash through a rinsing and filter pressing module to obtain rinsing wet ash and rinsing liquid; the rinsing liquid is subjected to impurity removal, oxidation and decoloration treatment through a multi-stage purification and filtration module, and a finished product liquid is obtained; and performing carbonization, salting-out and evaporation treatment on the finished product liquid through the salt separation module to obtain calcium carbonate, potassium sulfate, sodium bicarbonate and ammonium chloride. According to the method, collaborative resource utilization is achieved, the problem of disposal of two kinds of waste in iron and steel enterprises is solved, ammonia and iron elements in blast furnace gas condensate water are recycled, and potassium salt and sodium salt in sintering machine head ash are extracted to the maximum extent. The problem of environmental pollution caused by blast furnace gas condensate water and sintering machine head ash is solved, and good economic benefits are generated.

Description

Technical Field

[0001] The present invention relates to the technical field of waste resource recovery, and particularly to a system and method for comprehensive resource utilization. Background Art

[0002] Blast furnace gas condensate is one of the main wastewaters in blast furnaces of iron and steel enterprises at present. The pH value of blast furnace gas condensate is relatively low, and it contains a large amount of salts and other pollutants, mainly including chloride ions, iron ions, ammonia nitrogen, COD, as well as a small amount of calcium, magnesium, volatile phenol, etc. Compared with coking wastewater, the salt content and chloride ions in the blast furnace gas condensate of some iron and steel enterprises are several times or even more than 10 times that of coking wastewater. Acidic substances such as chlorides can corrode pipeline equipment. Especially when the chloride ion content is relatively high, it leads to high conductivity and electrochemical corrosion, accelerating the corrosion rate. Thus, it can be seen that the highly corrosive blast furnace gas condensate, if directly discharged without treatment, will pollute the soil, water bodies, and even harm the environment, and cause fluctuations in the quality of the in-plant circulating water. Therefore, it is very necessary to collect and treat the condensate.

[0003] In addition, sintering machine head ash is the soot collected by an electrostatic precipitator during the sintering process of raw materials such as iron ore, and it has a certain iron content. The traditional process directly returns the sintering machine head ash to the sintering process for recycling; however, the content of alkali metals, chlorine, etc. in the sintering machine head ash is high, and direct reuse will lead to the enrichment of harmful substances in the blast furnace, forming a vicious cycle, causing corrosion of the blast furnace wall, and further affecting the blast furnace campaign and actual operation; at the same time, the substances with high content of potassium, chlorine, etc. in the sintering machine head ash are potential potassium salt resources; therefore, in order to achieve efficient resource utilization, it is necessary to pretreat the sintering machine head ash to remove harmful substances and then conduct resource recovery.

[0004] In summary, there is an urgent need to develop a system and method for comprehensive resource utilization to solve the above problems. Summary of the Invention

[0005] In view of the technical problems existing in the background art, the present invention provides a system and method for comprehensive resource utilization, aiming to solve the technical problem that a large amount of blast furnace gas condensate and sintering machine head ash generated by existing iron and steel enterprises cannot be effectively disposed of.

[0006] In a first aspect, an embodiment of the present invention provides a system for comprehensive resource utilization, including a rinsing and pressure filtration module, a multi-stage purification and filtration module, and a salt separation module that are connected in sequence; Among them, the rinsing and pressure filtration module is used to perform water washing and pressure filtration on the slurry after mixing the blast furnace gas condensate water and the sintering machine head ash to obtain rinsed wet ash and rinsing liquid, and return the rinsed wet ash to the sintering machine; the multi-stage purification and filtration module is used to remove impurities, oxidize and decolorize the rinsing liquid to obtain a finished liquid and multi-stage purification slag, and return the multi-stage purification slag to the sintering machine; the salt separation module is used to perform carbonization, salting out and evaporation on the finished liquid to obtain calcium carbonate, potassium sulfate, sodium bicarbonate and ammonium chloride.

[0007] Preferably, the rinsing and pressure filtration module includes a rinsing unit and a pressure filtration unit connected in sequence; among them, the rinsing unit is used to perform rinsing on the slurry after mixing the blast furnace gas condensate water and the sintering machine head ash to obtain a rinsed slurry; the pressure filtration unit is used to perform pressure filtration on the rinsed slurry to obtain rinsed wet ash and rinsing liquid, and return the rinsed wet ash to the sintering machine.

[0008] Preferably, inside the rinsing unit: the pH value is 1.5 - 4, the mass ratio of the blast furnace gas condensate water to the sintering machine head ash is (2 - 4):1, and the rinsing time is 0.5 - 2h.

[0009] Preferably, the multi-stage purification and filtration module includes a magnesium and heavy metal removal filtration unit, an oxidation filtration unit and a decolorization filtration unit connected in sequence; Among them, the magnesium and heavy metal removal filtration unit is used to remove Mg 2+ and heavy metal ions in the rinsing liquid to obtain a first-stage purified liquid and a first-stage purification slag, and return the first-stage purification slag to the sintering machine; the oxidation filtration unit is used to oxidize the first-stage purified liquid to obtain a second-stage purified liquid and a second-stage purification slag, and return the second-stage purification slag to the sintering machine; the decolorization filtration unit is used to decolorize the second-stage purified liquid to obtain a finished liquid and a third-stage purification slag, and return the third-stage purification slag to the sintering machine.

[0010] Preferably, the reagents added in the magnesium and heavy metal removal filtration unit are NaOH, Na 2 S, polyferric chloride and a polymer coagulant aid; in the magnesium and heavy metal removal filtration unit: the pH value is 7 - 11; The reagent added in the oxidation filtration unit is ozone; in the oxidation filtration unit: the pH value is 7 - 9; the ozone concentration is 0.5mg / L, and the Fe 3+ concentration is 5 - 10mg / L; The reagent added in the decolorization filtration unit is activated carbon.

[0011] Preferably, the salt separation module includes a first carbonization filtration unit, a salting out filtration unit, a second carbonization filtration unit and an evaporation and crystallization filtration unit connected in sequence; Among them, the first carbonization and filtration unit is used to introduce carbon dioxide into the finished liquid to obtain calcium carbonate and the first filtrate; the salting-out and filtration unit is used to perform salting-out treatment on the first filtrate by adding a salting-out agent to obtain potassium sulfate and the second filtrate; the second carbonization and filtration unit is used to introduce carbon dioxide into the second filtrate to obtain sodium bicarbonate and the third filtrate; the evaporation, crystallization and filtration unit is used to perform evaporation and crystallization treatment on the third filtrate to obtain ammonium chloride and the fourth filtrate, and the fourth filtrate is returned to the salting-out and filtration unit.

[0012] Preferably, the salting-out agent includes at least one of methanol, diethanolamine, ethanolamine, and N-methylpyrrolidone, and the dosing concentration of the salting-out agent is 5-20 mmol / L.

[0013] Preferably, the temperature of the evaporation, crystallization and filtration unit is 80-120 °C.

[0014] In a second aspect, an embodiment of the present invention provides a method for comprehensive resource utilization, including the following steps: S1. Mix the blast furnace gas condensate water with the sintering machine head ash and perform rinsing and filtration to obtain a rinsing liquid and rinsed wet ash; S2. Perform magnesium and heavy metal removal treatment, oxidation treatment, and decolorization treatment on the rinsing liquid to remove magnesium ions, heavy metal ions, organic substances, and pigments in the rinsing liquid to obtain a finished liquid and multi-stage purification slag; S3. Perform carbon dioxide carbonization and filtration treatment, salting-out and filtration treatment, and evaporation and crystallization treatment on the finished liquid to obtain calcium carbonate, potassium sulfate, sodium bicarbonate, and ammonium chloride; The method for comprehensive resource utilization is implemented by using the above-mentioned system for comprehensive resource utilization.

[0015] Preferably, the rinsed wet ash is returned for sintering utilization, and the multi-stage purification slag is returned for sintering utilization.

[0016] Compared with the prior art, the beneficial effects of the present invention are as follows: The present invention provides a system and method for comprehensive resource utilization, which utilizes the acidic characteristics of blast furnace gas condensate water to dissolve insoluble minerals in the sintering machine head ash, reduces resource waste, and at the same time realizes collaborative resource utilization, solves the disposal problems of two kinds of wastes in iron and steel enterprises, not only recovers ammonia and iron elements in the blast furnace gas condensate water, but also maximally extracts potassium salts and sodium salts in the sintering machine head ash. By using multi-stage impurity removal processes such as heavy metal removal and oxidation and decolorization, and various methods for extracting and separating salts such as carbonization, salting-out, evaporation, and crystallization, salt products such as calcium carbonate, potassium sulfate, sodium bicarbonate, and ammonium chloride are produced, realizing the efficient utilization of resources. It not only solves the environmental pollution problems caused by blast furnace gas condensate water and sintering machine head ash, but also generates good economic benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1It is a structural framework diagram of the comprehensive resource utilization system provided by the embodiments of the present invention; Figure 2 It is a process flow diagram of the comprehensive resource utilization system provided by the embodiments of the present invention; Figure 3 It is a schematic flow diagram of the comprehensive resource utilization method provided by the embodiments of the present invention. Detailed implementation manners

[0018] Hereinafter, embodiments of the technical solutions of the present invention will be described in detail with reference to the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solutions of the present invention, so they are only examples and cannot be used to limit the protection scope of the present invention.

[0019] Please refer to Figure 1 and Figure 2 , the comprehensive resource utilization system provided by the embodiments of the present invention includes a rinsing and pressure filtering module, a multi-stage purification and filtering module, and a salt separation module connected in sequence; Among them, the rinsing and pressure filtering module is used to perform water washing and pressure filtering on the slurry after mixing blast furnace gas condensate water and sintering machine head ash to obtain rinsed wet ash and rinsing liquid, and return the rinsed wet ash to the sintering machine; the multi-stage purification and filtering module is used to perform impurity removal, oxidation and decolorization treatment on the rinsing liquid to obtain a finished liquid and multi-stage purification slag, and return the multi-stage purification slag to the sintering machine; the salt separation module is used to perform carbonization, salting out and evaporation treatment on the finished liquid to obtain calcium carbonate, potassium sulfate, sodium bicarbonate and ammonium chloride.

[0020] In the embodiments of the present invention, the rinsing and pressure filtering module includes a rinsing unit and a pressure filtering unit connected in sequence.

[0021] In the embodiments of the present invention, the rinsing unit is used to perform rinsing treatment on the slurry after mixing blast furnace gas condensate water and sintering machine head ash to obtain a rinsing slurry.

[0022] Specifically, the pH value in the rinsing unit is 1.5 - 4, the mass ratio of blast furnace gas condensate water to sintering machine head ash is (2 - 4):1, and the rinsing time is 0.5 - 2 h. A reasonable water-to-ash ratio setting can not only fully infiltrate the sintering machine head ash to effectively dissolve soluble potassium chloride and sodium chloride and remove impurities, but also not increase the burden and cost of subsequent treatment due to excessive water use. The reaction time is controlled within 0.5 - 1.5 h, which can not only ensure that soluble potassium chloride and sodium chloride in the ash have enough time to fully contact and dissolve with water, but also ensure the high efficiency of the treatment process. Since the pH value of the blast furnace gas condensate water is relatively low, the insoluble potassium feldspar in the sintering machine head ash reacts with the acid in the blast furnace gas condensate water and dissolves out (reaction equation: KAlSi 3 O 8 +4HCl + H 2 O = KCl + AlCl3 + 3H 2 SiO 3 ).

[0023] In the embodiment of the present invention, the pressure filtration unit is used to perform pressure filtration on the rinsing slurry to obtain rinsed wet ash and rinsing liquid, and the rinsed wet ash is returned to the sintering system.

[0024] In the embodiment of the present invention, the multi-stage purification and filtration module includes a magnesium and heavy metal removal filtration unit, an oxidation filtration unit, and a decolorization filtration unit that are connected in sequence.

[0025] During the rinsing process of the sintering machine head ash, a small amount of magnesium ions and heavy metal ions such as Pb, Zn, Cd, Mg, and Tl enter the solution. At the same time, there are a large amount of iron ions, as well as a small amount of heavy metal ions and organic substances in the blast furnace gas condensate water. Through the multi-stage purification and filtration module, the vast majority of heavy metal ions, magnesium ions, and organic substances are formed into precipitates and removed, and after decolorization, they enter the finished liquid storage tank.

[0026] In the embodiment of the present invention, the magnesium and heavy metal removal filtration unit is used to remove Mg 2+ and heavy metal ions in the rinsing liquid to obtain a primary purified liquid and a primary purified residue, and the primary purified residue is returned to the sintering machine.

[0027] Specifically, a reaction section, a coagulation section, a precipitation section, and a pressure filtration section are provided in the magnesium and heavy metal removal filtration unit. In the reaction section, magnesium and heavy metal removal agents NaOH, Na 2 S, and polyferric chloride are added. Among them, the main function of polyferric chloride is to play a flocculating role, making some formed cadmium chloride and lead chloride form large particles, which are easy to separate in the subsequent process. The pH is adjusted to alkaline (pH is 7-11), and after stirring and reacting for 40-60 minutes, PAC and PAM polymer coagulants are added to form larger flocs, and then precipitation is carried out. After precipitation for 0.5-2 hours, pressure filtration is carried out to obtain a primary purified liquid and a primary purified residue. The primary purified liquid enters the oxidation filtration unit, and the primary purified residue contains a large amount of iron and is directly returned to the sintering system of the steel enterprise. The main reaction equations in the magnesium and heavy metal removal filtration unit are as follows: 2Cl - +Cd 2+ =CdCl 2 ↓; 2Cl - +Pb 2+ =PbCl 2 ↓; Zn 2+ +2OH - =Zn(OH) 2 ↓; Mg 2+ +2OH - =Mg(OH)2 ↓; Fe 3+ + 3OH - = Fe(OH) 3 ↓; S 2- + 2Tl + = Tl 2 S↓.

[0028] In the embodiment of the present invention, the oxidation and filtration unit is used to perform oxidation treatment on the primary purified liquid to obtain a secondary purified liquid and a secondary purification residue, and the secondary purification residue is returned to the sintering machine.

[0029] Specifically, a reaction tank is provided in the oxidation and filtration unit. Ozone is introduced to oxidize and remove the organic matter in the primary purified liquid under alkaline conditions. The ozone concentration introduced into the reaction tank is 0.5 mg / L, the ozone contact time is 5 min to 10 min, the Fe 3+ concentration is 5 to 10 mg / L, the pH is 7 to 9, and the iron ions not completely removed by the magnesium and heavy metal removal unit are used as catalysts. The appropriate concentration of catalyst iron ions and trace ozone can regulate the selectivity of ozone oxidation. Under these conditions, organic matters such as phenol and chlorophenol are easily oxidized, and ammonia nitrogen (NH 4 + / NH 3 ) mainly exists in the form of ammonium ions (NH 4 + ) and is difficult to be oxidized. At the same time, some iron mud is generated in this stage. After the reaction liquid is pressure-filtered, a secondary purified liquid and a secondary purification residue are obtained. The secondary purification residue is mainly iron mud and is directly returned to the sintering system of the steel enterprise, and the secondary purified liquid is sent to the decolorization and filtration unit. In the oxidation and filtration unit, under alkaline conditions, with iron ions as catalysts, the reaction formula for ozone to oxidize organic matter (taking phenol as an example) is as follows: C 6 H 5 OH + O 3 + OH - → CO 2 + H 2 O.

[0030] In the embodiment of the present invention, the decolorization and filtration unit is used to perform decolorization treatment on the secondary purified liquid to obtain a finished product liquid and a tertiary purification residue, and the tertiary purification residue is returned to the sintering machine.

[0031] Specifically, the decolorization and filtration unit is provided with a reaction zone and a sedimentation zone; the secondary purified liquid is decolorized by adding activated carbon and stirring for 60 to 120 minutes, and then the filtrate and the tertiary purification residue are obtained after pressure filtration; the filtrate is further sedimented to remove fine particulate suspensions in the filtrate, and the supernatant liquid after sedimentation is the finished product liquid, which is sent to the salt separation module for resource utilization; the tertiary purification residue is activated carbon, which can be used as an auxiliary heat source in the sintering machine of the iron and steel enterprise or used for the purification of sintering flue gas after regeneration.

[0032] In the embodiment of the present invention, the salt separation module includes a first carbonization filtration unit, a salting-out filtration unit, a second carbonization filtration unit, and an evaporation crystallization filtration unit connected in sequence.

[0033] Specifically, the first carbonization filtration unit is used to introduce carbon dioxide into the finished product liquid to obtain calcium carbonate and the first filtrate. In the first carbonization filtration unit, carbon dioxide captured in the iron and steel enterprise plant is introduced into the finished product liquid. First, carbon dioxide reacts with ammonium ions in the finished product liquid to form ammonium bicarbonate, and then reacts with calcium ions in the finished product liquid to generate nano-calcium carbonate products. The reaction liquid is filtered by pressure to obtain calcium carbonate and the first filtrate, and the first filtrate enters the salting-out filtration unit. The main reaction equations in the first carbonization filtration unit are as follows: NH 3 ·H 2 O + CO 2 = NH 4 HCO 3 ; NH 4 HCO 3 + Ca 2+ = CaCO 3 ↓ + NH 4 + + H + .

[0034] Specifically, the salting-out filtration unit is used to perform salting-out treatment on the first filtrate by adding a salting-out agent to obtain potassium sulfate and the second filtrate. In the salting-out filtration unit, a salting-out agent is added to the first filtrate. The salting-out agent is one or several of methanol, diethanolamine, ethanolamine, and N-methylpyrrolidone. The addition amount of the salting-out agent is 5 - 20 mmol / L. The addition of the salting-out agent greatly reduces the solubility of potassium sulfate. As the amount of the salting-out agent increases, the solubility of potassium sulfate continues to decrease, while the solubility of other salts is basically not affected. Potassium sulfate precipitates due to the decrease in solubility to obtain potassium sulfate products. The solution is filtered by pressure to obtain the second filtrate and potassium sulfate products, and the second filtrate enters the second carbonization filtration unit.

[0035] Specifically, the second carbonization and filtration unit is used to introduce carbon dioxide into the second filtrate to obtain sodium bicarbonate and the third filtrate. In the second carbonization and filtration unit, carbon dioxide captured within the steel plant is introduced into the second filtrate. First, the carbon dioxide reacts with the ammonium ions in the second filtrate to form ammonium bicarbonate, and then reacts with the sodium ions to produce sodium bicarbonate products. This is because among the four salts NH 4 HCO 3 、NaCl、NH 4 Cl、NaHCO 3 , sodium bicarbonate has the lowest solubility. Therefore, under high ion concentration conditions, sodium bicarbonate will precipitate from the solution; after the reaction solution is pressure-filtered, sodium bicarbonate and the third filtrate are obtained, and the third filtrate enters the evaporation, crystallization, and filtration unit. The main reaction equations in the second carbonization and filtration unit are as follows: NH 3 ·H 2 O+CO 2 =NH 4 HCO 3 ; NH 4 HCO 3 +NaCl=NH 4 Cl+NaHCO 3 .

[0036] Specifically, the evaporation, crystallization, and filtration unit is used to perform evaporation and crystallization treatment on the third filtrate to obtain ammonium chloride and the fourth filtrate, and the fourth filtrate is returned to the salting-out and filtration unit. In the evaporation, crystallization, and filtration unit, the third filtrate undergoes evaporation and crystallization to obtain ammonium chloride products, and the unevaporated solution serves as the salting-out agent and is returned to the salting-out and filtration unit; among them, the temperature of the evaporation and crystallization unit is 80 - 120°C.

[0037] Please refer to Figure 3 , the comprehensive resource utilization method provided in this embodiment includes the following steps: S1. Mix the blast furnace gas condensate water with the sintering machine head ash and perform rinsing and filtration to obtain the rinsing solution and rinsed wet ash; S2. Perform magnesium and heavy metal removal treatment, oxidation treatment, and decolorization treatment on the rinsing solution to remove magnesium ions, heavy metal ions, organic substances, and pigments in the rinsing solution to obtain the finished product solution and multi-stage purification slag; S3. Perform carbon dioxide carbonization and filtration treatment, salting-out and filtration treatment, and evaporation and crystallization treatment on the finished product solution to obtain calcium carbonate, potassium sulfate, sodium bicarbonate, and ammonium chloride; Among them, the rinsed wet ash and multi-stage purification slag can be returned for sintering utilization.

[0038] Now, the technical solution of the present invention will be further described in combination with specific embodiments.

[0039] Example 1 The main characteristics of the sintering machine head ash of a certain iron and steel enterprise are as follows: Fe content is 220 - 270 g / kg, Ca content is 50 - 70 g / kg, Mg content is 5 - 10 g / kg, K content is 120 - 150 g / kg, Na content is 25 - 40 g / kg, Cl content is 200 - 300 g / kg, and the heavy metal content such as Pb, Zn, Cd, Tl is 10 - 20 g / kg; The main characteristics of the blast furnace gas condensate water of a certain iron and steel enterprise are as follows: chloride ion content is 120 - 160 g / L, sulfate ion content is 500 - 1000 mg / L, ammonia nitrogen content is 100 - 150 g / L, organic matter content is 500 - 1000 mg / L, and pH value is 1 - 4.

[0040] Please refer to Figure 1 , the comprehensive resource utilization system provided in this embodiment includes a rinsing and pressure filtering module, a multi-stage purification and filtering module, and a salt separation module connected in sequence; Among them, the rinsing and pressure filtering module is used to perform water washing and pressure filtering on the slurry after mixing the blast furnace gas condensate water and the sintering machine head ash to obtain rinsed wet ash and rinsing liquid, and return the rinsed wet ash to the sintering machine; The multi-stage purification and filtering module is used to perform impurity removal, oxidation, and decolorization on the rinsing liquid to obtain a finished liquid; The salt separation module is used to perform carbonization, salting out, and evaporation on the finished liquid to obtain calcium carbonate, potassium sulfate, sodium bicarbonate, and ammonium chloride.

[0041] Please refer to Figure 2 , Figure 2 is the process flow chart of the comprehensive resource utilization system provided in Embodiment 1 of the present invention; The specific process flow steps are as Figure 2 shown: (1) First, send the blast furnace gas condensate water and the sintering machine head ash to the rinsing unit of the rinsing and pressure filtering module. The mass ratio of the blast furnace gas condensate water to the sintering machine head ash in the rinsing unit is 3:1. Start rinsing and stirring, and the rinsing time is 2 h. Send the rinsed slurry to the pressure filtering unit for solid-liquid separation to obtain a filter cake and rinsing liquid. Wash the filter cake to further remove the residual soluble potassium chloride and sodium chloride. The desalted filter cake is the rinsed wet ash, which is directly returned to the sintering system of the iron and steel enterprise. The rinsing liquid is sent to the magnesium and heavy metal removal and filtering unit of the multi-stage purification and filtering module.

[0042] According to the water quality situation, use the blast furnace gas condensate water as the water source for water washing. The main reasons are as follows: The acidic characteristic (low pH value) of the blast furnace gas condensate water can effectively dissolve non-soluble minerals such as potassium feldspar in the sintering machine head ash. Through this co-treatment, valuable elements such as potassium and sodium in the sintering machine head ash can be dissolved out to form recoverable potassium salts and sodium salts. The main reaction equations are as follows: KAlSi 3 O 8 + 4HCl + H 2O = KCl + AlCl 3 + 3H 2 SiO 3 ). During the treatment process of blast furnace gas condensate, it undergoes a neutralization reaction with the alkaline substances in the sintering machine head ash, reducing the corrosiveness and treatment difficulty of the wastewater.

[0043] (2) A reaction section, a coagulation section, a sedimentation section, and a pressure filtration section are set in the magnesium and heavy metal removal filtration unit of the multi-stage purification and filtration module. In the reaction section, magnesium and heavy metal removal agents NaOH, Na 2 S, and polyferric chloride are added, and the pH is adjusted to alkaline (pH = 9). After stirring and reacting for 60 minutes, PAC and PAM polymer coagulants are added to form larger flocs, and then sedimentation is carried out. After sedimentation for 2 h, pressure filtration is performed to obtain the primary purified liquid and the primary purified residue. The primary purified liquid enters the oxidation and filtration unit, and the primary purified residue contains a large amount of iron and is directly returned to the sintering system of the steel enterprise. The main reaction equations in the magnesium and heavy metal removal filtration unit are as follows: 2Cl - +Cd 2+ =CdCl 2 ↓; 2Cl - +Pb 2+ =PbCl 2 ↓; Zn 2+ +2OH - =Zn(OH) 2 ↓; Mg 2+ +2OH - =Mg(OH) 2 ↓; Fe 3+ +3OH - =Fe(OH) 3 ↓; S 2- +2Tl + =Tl 2 S↓.

[0044] (3) A reaction tank is provided in the oxidation and filtration unit. The organic matter in the primary purified liquid is oxidized and removed by introducing ozone under alkaline conditions. After pressure filtration of the reaction liquid, the secondary purified liquid and the secondary purified residue are obtained. The secondary purified residue is mainly iron mud and is directly returned to the sintering system of the steel enterprise, and the secondary purified liquid is sent to the decolorization and filtration unit. In the oxidation and filtration unit, under alkaline conditions, with ferric ions as the catalyst, the reaction equation for ozone to oxidize organic matter (taking phenol as an example) is as follows: C 6 H 5 OH + O 3 + OH- → CO 2 +H 2 O。

[0045] Since the primary purified liquid contains a certain amount of COD, to avoid its impact on the quality of subsequent potassium, sodium, and calcium salts, it must be removed in the previous process. However, at the same time, it is desired to retain the ammonia nitrogen in the primary purified liquid and recover ammonium salt products in the subsequent treatment. Therefore, it is necessary to strictly control the selectivity of ozone oxidation. Through experimental research, it is obtained that under the conditions of pH 7 - 9, ozone concentration of 0.5 mg / L, ozone contact time of 5 min - 10 min, and Fe 3+ concentration of 5 - 10 mg / L, only a trace amount of ammonia nitrogen is oxidized, and mainly other organic substances in the water are oxidized.

[0046] (4) A reaction zone and a sedimentation zone are provided in the decolorization and filtration unit; the secondary purified liquid is decolorized by adding activated carbon, and then filtrate and tertiary purification residue are obtained after pressure filtration; the filtrate further settles to remove fine particulate suspended matter in the filtrate, and the supernatant after sedimentation is the finished product liquid, which is sent to the salt separation module for resource utilization; the tertiary purification residue is activated carbon, which can be used as an auxiliary heat source in the sintering machine of the iron and steel enterprise or regenerated and used for the purification of sintering flue gas.

[0047] (5) The finished product liquid is sent to the first carbonization and filtration unit of the salt separation module. In the first carbonization and filtration unit, carbon dioxide captured in the iron and steel enterprise is introduced into the finished product liquid. First, carbon dioxide reacts with ammonium ions in the finished product liquid to form ammonium bicarbonate, and then reacts with calcium ions in the finished product liquid to generate nano-calcium carbonate products. The reaction liquid is filtered by pressure to obtain calcium carbonate and the first filtrate, and the first filtrate enters the salting-out and filtration unit. The main reaction equations in the first carbonization and filtration unit are as follows: NH 3 ·H 2 O + CO 2 = NH 4 HCO 3 ; NH 4 HCO 3 + Ca 2+ = CaCO 3 ↓ + NH 4 + + H + 。

[0048] (6) In the salting-out filtration unit, a salting-out agent (N-methylpyrrolidone) is added to the first filtrate. The addition amount of the salting-out agent is 10 mmol / L. The addition of the salting-out agent greatly reduces the solubility of potassium sulfate, while the solubility of other salts is basically unaffected. Potassium sulfate precipitates due to the reduced solubility to obtain potassium sulfate products. The solution is filtered by pressure to obtain the second filtrate and potassium sulfate products. The second filtrate enters the second carbonization filtration unit.

[0049] (7) In the second carbonization filtration unit, carbon dioxide captured in the steel plant is introduced into the second filtrate. The carbon dioxide first forms ammonium bicarbonate with the ammonium ions in the second filtrate, and then reacts with sodium ions to form sodium bicarbonate products. This is because among the four salts NH 4 HCO 3 、NaCl、NH 4 Cl、NaHCO 3 , the solubility of sodium bicarbonate is the lowest. Therefore, under the condition of high ion concentration, sodium bicarbonate will precipitate from the solution. The reaction solution is filtered by pressure to obtain sodium bicarbonate and the third filtrate. The third filtrate enters the evaporation crystallization filtration unit. The main reaction equations in the second carbonization filtration unit are as follows: NH 3 ·H 2 O+CO 2 =NH 4 HCO 3 ; NH 4 HCO 3 +NaCl=NH 4 Cl+NaHCO 3 .

[0050] (8) In the evaporation crystallization filtration unit, the third filtrate is evaporated and crystallized to obtain ammonium chloride products. The unevaporated solution is the salting-out agent, which is returned to the salting-out filtration unit for continued use. Among them, the temperature of the evaporation crystallization unit is 102 °C.

[0051] It should be noted that the present invention is not limited to the above embodiments. The above embodiments are only examples. Embodiments having the same constitution as the technical idea and achieving the same effect within the technical solution scope of the present invention are all included in the technical scope of the present invention. In addition, within the scope not departing from the gist of the present invention, various modifications that can be thought of by those skilled in the art are applied to the embodiments, and other embodiments constructed by combining some constituent elements of the embodiments are also included in the scope of the present invention.

Claims

1. A system for comprehensive resource utilization, characterized in that: It includes a rinse filter press module, a multi-stage purification filter module, and a salt separation module which are connected in sequence; Among them, the rinsing filter press module is used to perform water washing and filter press treatment on the slurry mixed with blast furnace gas condensate and sintering machine head ash to obtain rinsed wet ash and rinse liquid, and return the rinsed wet ash to the sintering machine; the multi-stage purification filtration module is used to perform impurity removal, oxidation and decolorization treatment on the rinse liquid to obtain finished liquid and multi-stage purified slag, and return the multi-stage purified slag to the sintering machine; the salt separation module is used to perform carbonization, salting out and evaporation treatment on the finished liquid to obtain calcium carbonate, potassium sulfate, sodium bicarbonate and ammonium chloride.

2. A system for comprehensive resource utilization according to claim 1, characterized in that: The rinsing and filter pressing module includes a rinsing unit and a filter pressing unit connected in sequence; wherein the rinsing unit is used to perform a rinsing treatment on a slurry mixed with blast furnace gas condensate and sintering machine head ash to obtain a rinsing slurry; the filter pressing unit is used to perform a filter pressing treatment on the rinsing slurry to obtain a rinsing wet ash and a rinsing liquid, and return the rinsing wet ash to the sintering machine.

3. A system for comprehensive resource utilization according to claim 2, characterized in that: In the rinsing unit: the pH value is 1.5-4, the mass ratio of blast furnace gas condensate to sintering machine head ash is (2-4):1, and the rinsing time is 0.5-2h.

4. The system for comprehensive resource utilization according to claim 1, characterized in that: The multi-stage purification and filtration module comprises a magnesium removal and weight removal filtration unit, an oxidation filtration unit and a decolorization filtration unit connected in sequence; Wherein, the magnesium removal and weight removal filtering unit is used to remove the Mg in the rinsing liquid. 2+ After removing the heavy metal ions, a primary purified liquid and a primary purified slag are obtained, and the primary purified slag is returned to the sintering machine; The oxidation filtration unit is used to oxidize the primary purified liquid to obtain a secondary purified liquid and a secondary purified slag, and the secondary purified slag is returned to the sintering machine; The decolorization and filtering unit is used to decolorize the secondary purified liquid to obtain a finished liquid and a tertiary purified slag, and the tertiary purified slag is returned to the sintering machine.

5. A system for comprehensive resource utilization according to claim 4, characterized in that: The reagents added to the magnesium removal and weight removal filtering unit are NaOH, Na2S, polyferric chloride and polymer coagulant; in the magnesium removal and weight removal filtering unit: the pH value is 7-11; The reagent added to the oxidation filtration unit is ozone; in the oxidation filtration unit: the pH value is 7-9, the ozone concentration is 0.5 mg / L, Fe 3+ The concentration is 5~10mg / L; The reagent added to the decolorization and filtration unit is activated carbon.

6. The system for comprehensive resource utilization according to claim 1, characterized in that: The salt separation module comprises a first carbonization filtration unit, a salting-out filtration unit, a second carbonization filtration unit and an evaporation crystallization filtration unit connected in sequence; Wherein, the first carbonization filtration unit is used to obtain calcium carbonate and the first filtrate after introducing carbon dioxide into the finished liquid; The salting-out filtration unit is used to add a salting-out agent to the first filtrate for salting-out treatment to obtain potassium sulfate and a second filtrate; The second carbonization filtration unit is used to introduce carbon dioxide into the second filtrate to obtain sodium bicarbonate and a third filtrate; The evaporation crystallization filtration unit is used to perform evaporation crystallization treatment on the third filtrate to obtain ammonium chloride and a fourth filtrate, and the fourth filtrate is returned to the salting-out filtration unit.

7. A system for comprehensive resource utilization according to claim 6, characterized in that: The salting-out agent includes at least one of methanol, diethanolamine, ethanolamine, and N-methylpyrrolidone, and the addition concentration of the salting-out agent is 5-20 mmol / L.

8. The system for comprehensive resource utilization according to claim 6, characterized in that: The temperature of the evaporation crystallization filtration unit is 80-120°C.

9. A method for comprehensive resource utilization, characterized in that: The following steps are involved: S1, mixing blast furnace gas condensate with sintering machine head ash and rinsing and filtering to obtain rinsing liquid and rinsing wet ash; S2, subjecting the rinsing liquid to magnesium and weight removal treatment, oxidation treatment, and decolorization treatment to remove magnesium ions, heavy metal ions, organic matter and pigments in the rinsing liquid to obtain a finished liquid and multi-stage purified slag; S3, subjecting the finished liquid to carbonization filtration treatment, salting-out filtration treatment and evaporation crystallization treatment to obtain calcium carbonate, potassium sulfate, sodium bicarbonate and ammonium chloride; The method for comprehensive resource utilization is implemented by using the system for comprehensive resource utilization as described in any one of claims 1 to 8.

10. A method for comprehensive resource utilization according to claim 9, characterized in that: The rinsed wet ash is returned to sintering for utilization; and the multi-stage purified slag is returned to sintering for utilization.

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