WO2023036048A1

WO2023036048A1 - Method and system for recycling sintered ash

Info

Publication number: WO2023036048A1
Application number: PCT/CN2022/116533
Authority: WO
Inventors: 杨本涛; 彭建宏; 肖海娟; 陈瑶; 李佳; 冯哲愚; 肖祈春
Original assignee: 中冶长天国际工程有限责任公司
Priority date: 2021-09-07
Filing date: 2022-09-01
Publication date: 2023-03-16
Also published as: CN115921478A

Abstract

Disclosed are a method and system for recycling sintered ash. High-purity potassium chloride can be produced by using sintered ash generated in a sintering process of an iron and steel enterprise, the problems of equipment corrosion and agglomeration resulting from alkali metals and chlorine entering sintering, a blast furnace, a rotary kiln and other high-temperature furnaces or kilns is simultaneously avoided, and ammonia nitrogen and sulfate radicals can be removed at a low cost, to improve the quality of a recycled crystalline salt; further, multi-effect countercurrent evaporation is achieved by adjusting the potassium-sodium ratio, and then the value of the crystalline salt is further improved; in addition, the present invention also has the advantages of simple process conditions, low energy consumption, zero discharge of wastewater and the like.

Description

A kind of resource processing method and processing system of sintered ash

technical field

The invention relates to solid waste treatment in the iron and steel industry, in particular to a method and system for recycling sintered ash, and belongs to the technical field of recycling solid waste in the iron and steel industry.

Background technique

At present, the solid waste generated in the iron and steel industry mainly contains iron, most of which are recycled in the iron and steel plant through high-temperature furnaces such as sintering, blast furnaces, and rotary kilns. However, there are still some high-salt solid wastes (such as sintering third and fourth electric field ash, blast furnace bag dust), which contain more alkali and chlorine metals. If they are directly returned to high-temperature furnaces such as sintering, blast furnaces, and rotary kilns, equipment will be corroded. And cause unfavorable situations such as knot kiln.

For the high-salt solid waste generated in iron and steel plants, water washing is often used to remove alkali and chlorine metals, and to recover potassium and sodium salts. Such as Chinese patent CN101234766B "Using the method for producing potassium chloride by sintering electrostatic precipitator ash of iron and steel enterprises", it is reported that the leaching of sintering electric precipitator ash by tap water can greatly reduce the potassium and chlorine in the sinter ash, and the ash washing water is used to prepare potassium chloride ,Sodium chloride.

However, due to the complex composition of sintered ash, the composition of ash washing water is complex, such as containing a large amount of metal ions, ammonia nitrogen, sulfate radicals, etc. At present, the conventional sintered ash washing and waste water recycling process often adopts simple de-weighting followed by evaporation and crystallization. Ammonia nitrogen and sulfate radicals were not effectively removed. The quality of recovered salt is not high, affecting sales.

There are many ways to remove sulfate radicals in wastewater, such as barium chloride method, nanofiltration method, calcium oxide method, etc. 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. This method cannot be applied to the current washing water of sintered ash, because the concentration of sulfate radicals in the washing water is generally 1500-3000 ppm, so the above method cannot realize the deep removal of sulfate radicals in the 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 for callback, and the formed particles are relatively fine, which 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 and magnesium ions, which is difficult to operate and has high operating costs.

Contents of the invention

Aiming at the deficiencies of the prior art, the present invention provides a resourceful treatment method and system for sintered ash, which can produce high-purity potassium chloride by using the sintered ash produced in the sintering process of iron and steel enterprises, while avoiding the entry of alkali metals and chlorine Sintering, blast furnaces, rotary kilns and other high-temperature furnaces will cause equipment corrosion and kiln knotting problems. At the same time, the technical solution provided by the invention has the advantages of simple process conditions, low energy consumption, and no waste water discharge.

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 recycling sintered ash is provided.

A method for recycling sintered ash, the method comprising the following steps:

1) Water washing: Wash the sintered ash with water to obtain a filter cake and ash washing wastewater. The filter cake is transported outside for disposal, and the ash washing wastewater is processed in the next stage.

2) Wastewater pretreatment: Add mixed chemicals to the ash-washing wastewater to adjust the ash-washing wastewater to alkaline, and perform heavy and hard treatment on the ash-washing wastewater.

3) Ammonia gas recovery: heat the waste water after heavy and hard removal, and use the absorption liquid to recover ammonia gas to obtain ammonia removal waste water and ammonia-containing waste water.

4) Salt adjustment: add acid and sodium salt to the ammonia removal wastewater, adjust the ammonia removal wastewater to weak alkaline, and make the potassium and sodium content in the ammonia removal wastewater close to obtain high-salt wastewater.

5) Countercurrent evaporation: heating high-salt wastewater, concentrating and crystallizing, and solid-liquid separation to obtain sodium chloride and filtrate I. The filtrate I was subjected to cooling and crystallization, and solid-liquid separation was performed to obtain potassium chloride and filtrate II.

Preferably, the method also includes the following steps:

6) Elutriation: the potassium chloride obtained in step 5) is washed with a saturated potassium chloride solution to obtain high-purity potassium chloride and a concentrated solution containing sulfate radicals.

7) Ammonia removal: adding sulfite and ferrous salt to the ammonia-containing wastewater generated in step 3) to obtain deammonification wastewater.

8) Desulfurization: Mix the sulfuric acid root-containing concentrated solution produced in step 6) with the deammonification wastewater produced in step 7), then add calcium chloride and sodium metaaluminate to the mixed solution to obtain purified wastewater, after purification The waste water is recycled to step 1) as water for washing the sintered ash.

Preferably, the method also includes:

9) Internal circulation: the hot steam generated in step 5) circulates to step 3) as a heat source for heating. In the process of step 5), condensed water is also produced, and the condensed water is recycled to step 3) as an absorption liquid.

The sodium chloride produced in step 5) is recycled to step 4) to be added as sodium salt.

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

Preferably, the sintered ash is high-potassium and low-sodium ash. The potassium-sodium content ratio in the ash washing wastewater is not less than 1.5, preferably not less than 2, more preferably not less than 3.

Preferably, the water washing is multi-stage water washing, preferably three-stage countercurrent water washing. The water-cement ratio during washing is 2-7:1, preferably 2.5-5:1.

As preferably, in step 2), the mixed agent is sodium hydroxide and/or potassium hydroxide, sodium carbonate and/or potassium carbonate, sodium sulfide and/or potassium sulfate, recapture agent (such as 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 ash washing wastewater is 7-11, preferably 8-10. 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, the length of time for the ash-washing wastewater to undergo heavy and hard removal treatment is not less than 10 minutes, preferably not less than 15 minutes.

As a preference, in step 3), the method of recovering the ammonia gas is to use pumping to suck the ammonia gas into the absorption liquid. The pumping pressure is -100 to -50kPa, preferably -90 to -70kPa.

Preferably, the heating method is indirect heating, preferably jacket heating. The heating temperature is 40-70°C, preferably 50-60°C.

Preferably, in step 4), the acid is hydrochloric acid. The sodium salt is sodium chloride or potassium chloride, preferably sodium chloride.

As a preference, adjusting the pH of the ammonia removal wastewater to weakly alkaline is adjusting the pH of the ammonia removal wastewater to 7-8.5, preferably 7.5-8.

As a preference, making the potassium and sodium content in the ammonia removal wastewater close is to adjust the potassium and sodium ratio to 1:0.9-1.2, preferably 1:1-1.1.

Preferably, in step 5), the countercurrent evaporation is carried out using a multi-effect evaporator, and the number of stages of the multi-effect evaporator is 2-7, preferably 3-5.

Preferably, the heating of high-salt wastewater is heating of high-salt wastewater to 80-100°C, preferably 90-95°C.

Preferably, the cooling is to cool the high-salt wastewater to below 60°C, preferably 20-55°C.

Preferably, in step 7), the sulfite is a soluble sulfite, preferably one or more of sodium sulfite, potassium sulfite, sulfurous acid, and sulfur dioxide.

Preferably, the ferrous salt is a soluble ferrous salt, preferably ferrous chloride and/or ferrous sulfate.

As preferably, the addition of described soluble sulfite is such that the molar ratio of sulfite ion and ammonium ion in the ammoniacal wastewater is 1:0.2-2, preferably 1:0.5-1.5, more preferably 1:0.8 -1.2. The amount of the soluble ferrous salt added is such that the molar ratio of ferrous ions to ammonium ions in the ammonia-containing wastewater is 1:0.1-1.5, preferably 1:0.2-1.2, more preferably 1:0.5-1.

In step 8), the amount of calcium chloride added is such that the mol ratio of calcium ions and sulfate ions in the mixed solution is 1:0.1-0.5, preferably 1:0.2-1.4, more preferably 1:0.25- 0.3. The amount of sodium metaaluminate added is such that the molar ratio of aluminum ions to sulfate ions in the mixed solution is 1:0.2-2, preferably 1:0.5-1.5, more preferably 1:0.8-1.2.

According to the second embodiment of the present invention, a resource recovery treatment system for sintered ash is provided.

A resource treatment system for sintered ash or a treatment system for the method described in the first embodiment, the system includes a countercurrent water washing device, a heavy and hard removal pool, an ammonia reaction kettle, a salt adjustment pool, and a countercurrent multi-effect evaporator . The countercurrent water washing device, the heavy and hard removal tank, the ammonia analysis device, the salt adjustment tank, and the countercurrent multi-effect evaporator are connected in series in sequence. The countercurrent water washing device is also provided with a water inlet and an ash inlet. There is also a dosing port on the heavy and hard removing pool. An exhaust port is also arranged on the ammonia analysis reactor. The salt adjustment tank is also provided with acid and salt inlets. The countercurrent multi-effect evaporator is also connected to a condensate storage tank through a condensate delivery pipeline. The condensed water storage tank is connected with the vacuum pump through the evacuation pipe. The exhaust port of the ammonia analysis reactor is connected with the air inlet of the condensed water storage tank through the ammonia gas delivery pipeline. The drain port of the condensed water storage tank is connected with the countercurrent washing device through a circulating water pipe.

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 pipelines. 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 salt addition port of the salt adjustment tank through the sodium salt delivery device. The cooling unit is also provided with a potassium salt outlet, and the potassium salt outlet communicates with the feed port of the elutriation unit through the potassium salt conveying device.

Preferably, the system also includes a deammonization device and a desulfurization device. Both the deammonization device and the desulfurization device are arranged on the circulating water pipe, and the desulfurization device is located downstream of the deammonization device. The desulfurization device is also provided with a concentrated liquid inlet, and the concentrated liquid inlet is connected with the concentrated liquid outlet of the elutriation unit through the concentrated liquid conveying pipeline.

In the prior art, in order to avoid problems such as alkali metals and chlorine elements in sintered ash that would cause equipment corrosion and unfavorable conditions such as kiln construction, water washing is often used to remove alkali and chlorine metals, and potassium and sodium salts are recovered . However, due to the complex composition of sintered ash, the composition of ash washing water is complex, such as containing a large amount of metal ions, ammonia nitrogen, sulfate radicals, etc. The potassium salt that causes recovery has more impurities, and the purity is relatively low, which affects its utilization. Generally, for sintered ash washing wastewater with more potassium than sodium, potassium salt is usually precipitated first, and then sodium salt is precipitated. On the one hand, potassium salt is precipitated first, and impurities and pollutants are easily precipitated with the precipitation of potassium salt, reducing the potassium 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, the sintered ash is dechlorinated through a three-stage countercurrent washing process. The filter cake obtained after water washing is transported outside for disposal, and the ash-washing wastewater obtained after water washing enters the regulating tank. Then add mixed reagent (such as adding sodium hydroxide, sodium carbonate, sodium sulfide, the mixed reagent that recapture agent forms successively in regulating tank, the add-on of sodium hydroxide is mainly to be 7～11 in order to regulate the pH of solution, sodium carbonate , Sodium sulfide, recapture agent, etc. are used to remove heavy and hard wastewater, and separate heavy metal ions and calcium and magnesium in the water.) Transport the waste water after weight removal and hard removal to the ammonia reaction kettle, and heat the ammonia reaction kettle (for example, pass the low-temperature waste heat steam after subsequent evaporation and crystallization into the jacket of the reaction kettle) and at the same time, the top of the ammonia reaction kettle Connected with the vacuum pump of the subsequent multi-effect evaporation system, under the action of the vacuum pump, the ammonia gas precipitated in the waste water is continuously sucked out and passed into the absorption liquid (the absorption liquid is generally the condensed water produced by the subsequent multi-effect evaporation device). Then use hydrochloric acid to adjust the pH of the solution to 7-8 in the waste water after ammonia removal, and add a certain amount of sodium salt at the same time (except for the first time adding sodium salt, the sodium salt produced by the multi-effect evaporator can be added later. Can), adjust the content of potassium and sodium in the solution to be close (for example, adjust the ratio of potassium and sodium to about 1:1), and obtain 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 enters the elutriation device, and is washed with a saturated potassium chloride solution to remove sulfate radicals. After centrifugation, high-purity potassium chloride is obtained, and the remaining sulfate-containing dope Then sent to the desulfurization device for desulfurization treatment. Further, the condensed water produced by multi-effect evaporation and crystallization is used for the absorption of ammonia, and sodium sulfite and ferrous chloride are added to the condensed water that has absorbed ammonia to precipitate ammonia nitrogen (generate ammonium ferrous sulfite) to complete the precipitation of ammonia nitrogen After simple aeration, the final solution is mixed with the concentrated solution containing sulfate radicals obtained from elutriation, and then enters the desulfurization device, and then calcium chloride and sodium metaaluminate are added to precipitate sulfate radicals; the waste water after desulfurization is recycled to In the three-stage countercurrent washing process, it can replace part of the industrial water for circulating washing, thereby realizing zero discharge of waste water.

In the present invention, after adding mixed medicament to the ash-washing wastewater obtained after water washing to realize alkali adjustment, heavy removal and hardness removal of the wastewater, the wastewater will be alkaline, and the ammonia nitrogen in the wastewater will be converted into ammonia gas under the alkali adjustment. In the prior art, the removal of ammonia nitrogen is generally carried out by stripping or distilling ammonia, but this method requires additional equipment and requires high investment. The invention adopts an ammonia analysis reaction kettle with a jacket layer, which can realize low-cost removal of ammonia nitrogen. The ammonia reaction kettle is similar to the evaporation crystallization reactor, the top is connected with a vacuum pump, and can be heated by steam (steam enters the jacket and circulates for heating). This design can be perfectly matched with the multi-effect evaporation and crystallization system, and the low-temperature steam of evaporation and crystallization is used for heating, which reduces energy consumption and does not add an additional vacuum system, so that the ammonia nitrogen in the wastewater enters the condensed water (through the multi-effect evaporator Supporting vacuum pump pumping), so as to realize the low-cost removal and recovery of ammonia gas.

In the present invention, since the sintered ash is high-potassium and low-sodium ash, the ratio of potassium to sodium in the washing solution is generally not lower than 3. According to the phase diagram analysis of potassium and sodium salts by variable temperature evaporation, after the high potassium and low sodium solution is concentrated by evaporation, potassium salts will inevitably be precipitated first. Therefore, the salt separation method of sintered 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 regulates the ratio of potassium to sodium close to 1:1 by adding sodium salt or returning the sodium salt evaporated from the multi-effect evaporator to the solution. Then the evaporation process can be adjusted to countercurrent evaporation, that is, the solution is gradually heated up during the evaporation process. At the outlet of the first effect, the sodium salt is discharged first. This evaporation method precipitates pollutants along with the precipitation of sodium, and will not enter the potassium salt, which is conducive to improving 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 sulfate radical removal process in potassium chloride salt generally has the problem of difficulty in the advanced treatment of sulfate radicals, and excessive medicaments are often required to achieve complete removal. The present invention is analyzed according to the properties of the sulfate radical, which will enter into the solid salt along with potassium chloride. Therefore, when the potassium chloride solid is precipitated in the multi-effect evaporator, the copper drum is washed with a saturated potassium chloride solution (ceramic multiple times), so as to realize the dissolution and enrichment of sulfate radicals in potassium chloride, and obtain high sulfate radical Concentrated solution, and the concentrated solution is then subjected to deep removal of sulfate radicals, thus perfectly solving the problem of difficult sulfate radical removal, and at the same time further improving the purity of potassium chloride.

In the present invention, the absorption liquid recovered by the ammonia analysis is the condensed water produced by the system, and the concentrated solution containing sulfate radicals produced by elutriation is only taken out from the system, and the open circuit of ammonia nitrogen and sulfate radicals has not been fully realized. Based on the principle of not generating additional ions, the present invention adds ferrous and sulfite to the condensed water to convert ammonia nitrogen into ammonium ferrous sulfite and precipitate, thereby realizing the removal of ammonia nitrogen. After the ammonia nitrogen precipitation solution is simply aerated, it is mixed with the sulfate-containing concentrated solution, and then calcium chloride and sodium metaaluminate are added to the mixed solution to convert the sulfate into ettringite precipitation. Finally, the removal of ammonia nitrogen and sulfate radicals is achieved. The remaining waste water replaces part of the industrial water for circulating water washing of the sintered ash to achieve zero discharge of waste water.

In the present invention, the water washing of sintered ash is multi-stage water washing, generally three-stage counter-current water washing, and the three-stage counter-current water washing process is that after the sintered ash is washed by one-stage water, it is dewatered by one-stage filter press, and the filtrate is discharged into subsequent wastewater Recycling treatment system, 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.

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

1: For the removal of ammonia nitrogen in wastewater, the present invention uses the waste heat steam and vacuum device of the subsequent multi-effect evaporation system to absorb the ammonia nitrogen into the condensed water generated during the evaporation process, and then uses the ferrous ammonium sulfite method for precipitation, which has a cost Low cost, simple operation, no additional equipment and energy consumption, reasonable use of resources in the system, realization of digestion in the system, and reduction of pollutant emissions.

2: The present invention aims at ash-washing wastewater with high potassium and low sodium, and adjusts the potassium-sodium ratio in the solution to be close to 1:1 by adding additional sodium salt, so as to match the countercurrent evaporation with wider applicability, more energy saving and less investment The device can not only greatly improve the quality of the recovered potassium salt, but also greatly reduce energy consumption and improve production efficiency.

3: Compared with the traditional process, the scheme of the present invention can avoid the introduction of other ions when directly removing impurities in the wastewater by improving the evaporation mechanism and process route, and reduce the ammonia nitrogen, sulfate radical, chroma, etc. that affect the recovery of potassium salt. The removal of cost further improves the quality of the recovered potassium salt and prevents pollutants from entering the potassium salt, thereby increasing the value of the potassium chloride product.

Description of drawings

Fig. 1 is a process flow chart of the recycling treatment method of sintered ash according to the present invention.

Fig. 2 is a schematic structural diagram of a system for recycling sintered ash according to the present invention.

Reference signs: 1: countercurrent washing device; 101: ash inlet; 102: water inlet pipe; 2: heavy and hard removal tank; 3: ammonia analysis reactor; 301: ammonia gas delivery pipeline; 4: salt adjustment tank; 5 : Countercurrent multi-effect evaporator; 501: Heating unit; 502: Cooling unit; 503: Elutriation unit; 504: Condensed water delivery pipeline; 505: Circulating infusion tube; 506: Sodium salt delivery device; 6: Condensed water storage tank; 601: Evacuation pipe; 602: Circulating water pipe; 7: Vacuum pump; 8: Deamination device; 9: Desulfurization device;

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 resource treatment system for sintered ash, the system includes a countercurrent water washing device 1, a heavy and hard removal tank 2, an ammonia analysis reaction kettle 3, a salt adjustment tank 4 and a countercurrent multi-effect evaporator 5. The countercurrent water washing device 1 , heavy and hard removal tank 2 , ammonia analysis device 3 , salt adjustment tank 4 , and countercurrent multi-effect evaporator 5 are connected in series in sequence. The countercurrent water washing device 1 is also provided with a water inlet and an ash inlet. The pond 2 for removing heavy and hard is also provided with a drug-feeding port. The ammonia analysis reactor 3 is also provided with an exhaust port. The salt-adjusting pool 4 is also provided with an acid-adding port and a salt-adding port. The countercurrent multi-effect evaporator 5 is also connected to a condensed water storage tank 6 through a condensed water delivery pipe 504 . The condensed water storage tank 6 is connected with the vacuum pump 7 through an evacuation pipe 601 . The exhaust port of the ammonia analysis reactor 3 is connected to the air inlet of the condensed water storage tank 6 through the ammonia gas delivery pipeline 301 . The drain port of the condensed water storage tank 6 communicates with the countercurrent washing device 1 through a circulating water pipe 602 .

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 a pipeline. The liquid outlet of the cooling unit 502 communicates with the water inlet of the heating unit 501 through a circulation infusion pipe 505 . The heating unit 501 is also provided with a sodium salt outlet, and the sodium salt outlet communicates with the salt addition port of the salt adjusting tank 4 through the sodium salt delivery device 506 . The cooling unit 502 is also provided with a potassium salt outlet, and the potassium salt outlet communicates with the feed port of the elutriation unit 503 through a potassium salt conveying device 507 .

Preferably, the system further includes a deammonization device 8 and a desulfurization device 9 . Both the deammonization device 8 and the desulfurization device 9 are arranged on the circulating water pipe 602 , and the desulfurization device 9 is located downstream of the deammonization device 8 . The desulfurization device 9 is also provided with a concentrated liquid inlet, and the concentrated liquid inlet is connected with the concentrated liquid outlet of the elutriation unit 503 through the concentrated liquid delivery pipeline 901 .

Example 1

As shown in FIG. 2 , a system for recycling sintered ash, the system includes a countercurrent washing device 1 , a deduplication and hardening tank 2 , an ammonia analysis reactor 3 , a salt adjustment tank 4 and a countercurrent multi-effect evaporator 5 . The countercurrent water washing device 1, the heavy and hard removal pond 2, the ammonia analysis device 3, the salt adjustment pond 4, and the countercurrent multi-effect evaporator 5 are connected in series successively. The countercurrent water washing device 1 is also provided with a water inlet and an ash inlet. The pond 2 for removing heavy and hard is also provided with a drug-feeding port. The ammonia analysis reactor 3 is also provided with an exhaust port. The salt-adjusting pool 4 is also provided with an acid-adding port and a salt-adding port. The countercurrent multi-effect evaporator 5 is also connected to a condensed water storage tank 6 through a condensed water delivery pipe 504 . The condensed water storage tank 6 is connected with the vacuum pump 7 through an evacuation pipe 601 . The exhaust port of the ammonia analysis reactor 3 is connected to the air inlet of the condensed water storage tank 6 through the ammonia gas delivery pipeline 301 . The drain port of the condensed water storage tank 6 communicates with the countercurrent washing device 1 through a circulating water pipe 602 .

Example 2

Repeat Example 1, except that 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 a pipeline. The liquid outlet of the cooling unit 502 communicates with the water inlet of the heating unit 501 through a circulation infusion pipe 505 . The heating unit 501 is also provided with a sodium salt outlet, and the sodium salt outlet communicates with the salt addition port of the salt adjusting tank 4 through the sodium salt delivery device 506 . The cooling unit 502 is also provided with a potassium salt outlet, and the potassium salt outlet communicates with the feed port of the elutriation unit 503 through a potassium salt conveying device 507 .

Example 3

Repeat Example 2, except that the system also includes a deammonization device 8 and a desulfurization device 9 . Both the deammonization device 8 and the desulfurization device 9 are arranged on the circulating water pipe 602 , and the desulfurization device 9 is located downstream of the deammonization device 8 . The desulfurization device 9 is also provided with a concentrated liquid inlet, and the concentrated liquid inlet is connected with the concentrated liquid outlet of the elutriation unit 503 through the concentrated liquid delivery pipeline 901 .

Example 4

As shown in Figure 1, a kind of resource treatment method of sintered ash, this method comprises the following steps:

Example 5

Example 6

9) Internal circulation: the hot steam generated in step 5) circulates to step 3) as a heat source for heating. In the process of step 5), condensed water is also produced, and the condensed water is recycled to step 3) as an absorption liquid. The sodium chloride produced in step 5) is recycled to step 4) to be added as sodium salt. The filtrate II produced in step 5) is mixed with the high-salt wastewater produced in step 4), and then the countercurrent evaporation treatment is continued.

Application Example 1

Wash 100kg of sintered power plant ash (with a potassium content of about 28.5% and a sodium content of 7.1%) with a three-stage countercurrent washing device, and press filter to obtain a filter cake and about 300L of ash washing wastewater (wherein the potassium and sodium content ratio is about 3.4), The filter cake is transported out for disposal; then sodium hydroxide is first added to the ash washing wastewater to adjust the pH of the wastewater to 8.5, and then 2.5kg of sodium carbonate, 450g of sodium sulfide, and 600g of dithiocarbamate are sequentially added to the ash washing wastewater Recapture agent, stir and mix for 30 minutes; filter, use steam to heat the filtrate in the ammonia reaction kettle, and suck the generated ammonia gas into the condensed water through a vacuum pump to obtain ammonia removal wastewater and ammonia-containing wastewater; continue to remove ammonia wastewater Add hydrochloric acid to adjust the pH to 7.5, add sodium chloride to adjust the content ratio of potassium chloride and sodium chloride in the wastewater to about 1:1, and obtain high-salt wastewater. Heat high-salt wastewater to 95°C in a multi-effect countercurrent evaporator, concentrate and crystallize, and centrifuge to obtain sodium chloride (which can be used as a sodium salt for adjusting the ratio of potassium to sodium) 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 99.93%) and a concentrated solution containing sulfate radicals. Adding sulfite and ferrous salt to the ammonia-containing wastewater to carry out precipitation reaction, and filtering after completion of the reaction to obtain deammonification wastewater and ammonium ferrous sulfite. The sulfuric acid root-containing concentrated liquid and the deamination waste water are mixed, and calcium chloride and sodium metaaluminate are added to the mixed liquid for precipitation reaction. After the reaction is completed, filter to obtain ettringite and purified waste water, and the purified waste water is recycled to three The three-stage washing water used as sintered ash in the three-stage countercurrent washing device. The hot steam generated by the multi-effect countercurrent evaporator is circulated to the ammonia analysis reactor as a heat source for heating the ammonia analysis.

Application Example 2

120kg of sintered power plant ash (potassium content is 23.8%, sodium content is 5.4%) is washed with water by a three-stage countercurrent washing device, and filter cake and about 330L ash washing wastewater (wherein the potassium and sodium content ratio is about 4.72) are obtained after press filtration. The filter cake is transported out for disposal; then first add sodium hydroxide to the ash washing wastewater to adjust the pH of the wastewater to 9, and then add 2.4kg of sodium carbonate, 660g of sodium sulfide, and 500g of dithiocarbamates to the ash washing wastewater in sequence Recapture agent, stir and mix for 30 minutes; filter, use steam to heat the filtrate in the ammonia reaction kettle, and suck the generated ammonia gas into the condensed water through a vacuum pump to obtain ammonia removal wastewater and ammonia-containing wastewater; continue to add ammonia to the ammonia removal wastewater Add hydrochloric acid to adjust the pH to 8, add sodium chloride to adjust the content ratio of potassium chloride and sodium chloride in the wastewater to about 1:1, and obtain high-salt wastewater. Heat the high-salt wastewater to 95°C in a multi-effect countercurrent evaporator, concentrate and crystallize, and centrifuge to obtain sodium chloride (which can be used as a sodium salt for adjusting the ratio of potassium to sodium) 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 99.91%) and a concentrated solution containing sulfate radicals. Adding sulfite and ferrous salt to the ammonia-containing wastewater to carry out precipitation reaction, and filtering after completion of the reaction to obtain deammonification wastewater and ammonium ferrous sulfite. Mix the concentrated solution containing sulfate radicals with the deamination wastewater, and add calcium chloride and sodium metaaluminate to the mixed solution for precipitation reaction. After the reaction is completed, filter to obtain ettringite and purified water, and the purified wastewater is recycled to three The three-stage washing water used as sintered ash in the three-stage countercurrent washing device. The hot steam generated by the multi-effect countercurrent evaporator is circulated to the ammonia analysis reactor as a heat source for heating the ammonia analysis.

Claims

A method for recycling sintered ash, characterized in that the method comprises the following steps:

1) Water washing: washing the sintered ash with water to obtain filter cake and ash washing wastewater, the filter cake is transported outside for disposal, and the ash washing wastewater is subjected to the next level of treatment;

2) Wastewater pretreatment: Add mixed chemicals to the ash-washing wastewater to adjust the ash-washing wastewater to alkaline, and perform heavy and hard treatment on the ash-washing wastewater;

3) Ammonia gas recovery: heating the waste water after heavy removal and hard removal, and using the absorption liquid to recover ammonia gas to obtain ammonia removal waste water and ammonia-containing waste water;

4) Salt adjustment: add acid and sodium salt to the ammonia removal wastewater, adjust the ammonia removal wastewater to weak alkaline, and make the potassium and sodium content in the ammonia removal wastewater close to obtain high-salt wastewater;

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

6) elutriation: the potassium chloride obtained in step 5) is washed with a saturated potassium chloride solution to obtain high-purity potassium chloride and a concentrated solution containing sulfate radicals;

7) Ammonia removal: adding sulfite and ferrous salt to the ammonia-containing wastewater generated in step 3) to obtain deammonification wastewater;

8) Desulfurization: Mix the sulfuric acid root-containing concentrated solution produced in step 6) with the deammonification wastewater produced in step 7), then add calcium chloride and sodium metaaluminate to the mixed solution to obtain purified wastewater, after purification The waste water is circulated to step 1) as the washing water of sintered ash;

Preferably, the method also includes:

9) Internal circulation: the hot steam generated in step 5) circulates to step 3) as a heat source for heating; in the process of step 5), condensed water is also produced, and the condensed water is circulated to step 3) as an absorption liquid; and/ or

The sodium chloride produced in step 5) is recycled to step 4) to be added as sodium salt; and/or

The filtrate II produced in step 5) is mixed with the high-salt wastewater produced in step 4), and then the countercurrent evaporation treatment is continued.
The method according to claim 1 or 2, characterized in that: the sintered ash is high-potassium and low-sodium ash; the potassium-sodium content ratio in the ash-washing wastewater is not less than 1.5, preferably not less than 2, more preferably is not less than 3;

The washing is multi-stage washing, preferably three-stage countercurrent washing; the water-cement ratio during washing is 2-7:1, preferably 2.5-5:1.
according to the method described in any one in claim 1-3, it is characterized in that: in step 2) 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 (preferably xanthate class recapture agent or dithiocarbamate class recapture agent) are jointly formed; Wherein: the add-on of sodium hydroxide and/or potassium hydroxide is The pH of the ash washing wastewater is 7-11, preferably 8-10; the addition of the sodium carbonate and/or potassium carbonate is 3-10g/L, preferably 4-8g/L; the sodium sulfide and/or Or the addition of potassium sulfide is 1-7g/L, preferably 1.5-6g/L; the addition of the recapture agent is 1-8g/L, preferably 2-5g/L;

Preferably, the length of time for the ash-washing wastewater to undergo heavy and hard removal treatment is not less than 10 minutes, preferably not less than 15 minutes.
According to the method described in any one of claims 1-4, it is characterized in that: in step 3), the way of said ammonia gas recovery is to use pumping to suck ammonia gas into the absorption liquid; the pressure of pumping -100 to -50kPa, preferably -90 to -70kPa;

The heating method is indirect heating, preferably jacket heating; the heating temperature is 40-70°C, preferably 50-60°C.
The method according to any one of claims 1-5, characterized in that: in step 4), the acid is hydrochloric acid; the sodium salt is sodium chloride or potassium chloride, preferably sodium chloride;

The adjustment of ammonia removal wastewater to weak alkaline is to adjust the pH of ammonia removal wastewater to 7-8.5, preferably 7.5-8;

To make the content of potassium and sodium in the ammonia removal wastewater close is to adjust the ratio of potassium and sodium to 1:0.9-1.2, preferably 1:1-1.1.
The method according to any one of claims 1-6, characterized in that: in step 5), countercurrent evaporation is carried out using a multi-effect evaporator, and the number of stages of the multi-effect evaporator is 2-7, preferably 3 - level 5;

The heating high-salt wastewater is heating high-salt wastewater to 80-100°C, preferably 90-95°C;

The cooling is to cool the high-salt wastewater to below 60°C, preferably 20-55°C.
The method according to any one of claims 1-7, characterized in that: in step 7), the sulfite is a soluble sulfite, preferably sodium sulfite, potassium sulfite, sulfurous acid, sulfur dioxide one or more; and/or

The ferrous salt is a soluble ferrous salt, preferably ferrous chloride and/or ferrous sulfate;

As preferably, the addition of described soluble sulfite is such that the molar ratio of sulfite ion and ammonium ion in the ammoniacal wastewater is 1:0.2-2, preferably 1:0.5-1.5, more preferably 1:0.8 -1.2; the add-on of the soluble ferrous salt is to make the mol ratio of ferrous ion and ammonium ion in the ammoniacal wastewater be 1:0.1-1.5, preferably 1:0.2-1.2, more preferably 1:0.5- 1;

In step 8), the amount of calcium chloride added is such that the mol ratio of calcium ions and sulfate ions in the mixed solution is 1:0.1-0.5, preferably 1:0.2-1.4, more preferably 1:0.25- 0.3; the amount of sodium metaaluminate added is such that the molar ratio of aluminum ions to sulfate ions in the mixed solution is 1:0.2-2, preferably 1:0.5-1.5, more preferably 1:0.8-1.2.
A system for resourceful treatment of sintered ash according to any one of claims 1-8, characterized in that the system includes a countercurrent washing device (1), a heavy and hard removal pool (2), an analysis Ammonia reaction kettle (3), salt adjusting tank (4) and countercurrent multi-effect evaporator (5); 4), countercurrent multi-effect evaporators (5) are connected in series in sequence; the countercurrent water washing device (1) is also provided with a water inlet and an ash inlet; The ammonia reactor (3) is also provided with an exhaust port; the salt adjustment pool (4) is also provided with an acid inlet and a salt inlet; the countercurrent multi-effect evaporator (5) is also connected with a Condensed water storage tank (6); Condensed water storage tank (6) is connected with vacuum pump (7) through evacuating pipe (601) again; The air inlet of the condensed water storage tank (6) is connected; the drain of the condensed water storage tank (6) is connected with the countercurrent washing device (1) through a circulating water pipe (602);

As preferably, the countercurrent multi-effect evaporator (5) includes a heating unit (501), a cooling unit (502) and an elutriation unit (503); The liquid port is connected through a pipeline; the liquid discharge port of the cooling unit (502) is connected with the water inlet of the heating unit (501) through a circulation transfusion pipe (505); the heating unit (501) is also provided with a sodium salt outlet, and the sodium salt The outlet communicates with the salt addition port of the salt adjusting tank (4) through the sodium salt conveying device (506); the cooling unit (502) is also provided with a potassium salt outlet, and the potassium salt outlet passes through the potassium salt conveying device (507) and the elutriation unit (503) feed ports are connected.
The system according to claim 9, characterized in that: the system also includes a deammonization device (8) and a desulfurization device (9); the deammonization device (8) and the desulfurization device (9) are all arranged in the circulating water pipe ( 602), and the desulfurization device (9) is located downstream of the deammonization device (8); the desulfurization device (9) is also provided with a concentrated liquid inlet, which passes through the concentrated liquid delivery pipeline (901) and the elutriation unit The dope outlet of (503) is connected.