A method for synergistically treating magnesium-based desulfurization wastewater and garbage fly ash

Abstract

The present invention discloses a method for the coordinated treatment of magnesium desulfurization wastewater and garbage fly ash, which relates to the technical field of "three wastes" treatment, and solves the problem of long process flow and high cost of separate treatment of existing magnesium desulfurization wastewater and garbage fly ash. The method comprises: step 1, mixing garbage fly ash with washed clean coal to obtain a first mixture; step 2, ball-milling the first mixture in step 1, adding magnesium desulfurization wastewater, heavy oil and additives to perform grinding and pulping to obtain slurry; step 3, sending the slurry into a garbage incineration boiler for combustion. The present invention combines garbage fly ash and magnesium desulfurization wastewater for coordinated treatment, which can reduce the amount of new water used and reduce costs.

Description

Technical Field

[0001] The invention belongs to the technical field of "three wastes" treatment, and specifically relates to a method for coordinating the treatment of magnesium-based desulfurization wastewater and garbage fly ash. Background Art

[0002] Magnesium desulfurization is a process that uses magnesium oxide and hydroxide as SO 2 Typical wet desulfurization technology with absorbent. Due to the abundant magnesium oxide reserves in my country, the scale and investment of magnesium desulfurization system are smaller than those of limestone-gypsum method, and the by-product magnesium sulfate has a higher use value, so it has been promoted and applied to a certain extent in the steel industry. The problem of magnesium desulfurization of sintering flue gas in steel plants is to remove SO in the flue gas. 2 At the same time, a large amount of wastewater is also produced. The main salt ions in the magnesium desulfurization wastewater are Mg 2+ , Ca 2+ 、SO4 2- , Cl - The main pollutants exceeding the standard are suspended solids, chlorides, sulfates, COD cr , fluoride, total mercury, sulfide, total cadmium, total nickel and total zinc, etc., and the concentration of sulfite / sulfate can reach 120-200g / L, which is several times or even dozens of times higher than that of ordinary wastewater. Mg(OH) 2 、CaSO 4 The wastewater after the sedimentation of heavy metal hydroxides is also difficult to reach the quality of industrial water.

[0003] With the rapid development of my country's economy, the amount of urban domestic waste generated is huge. At present, the domestic treatment of urban domestic waste is usually carried out by incineration power generation. During the incineration process, the waste incineration fly ash (referred to as waste fly ash) collected by the boiler dust removal system contains certain organic matter and heavy metal elements such as Hg, Zn, As, Pb, Cu, and highly toxic substances such as dioxins. Therefore, waste fly ash is currently classified as hazardous waste management. There are four main existing treatment technologies for waste fly ash, including cement solidification, chemical agent treatment, acid solvent extraction, and melt solidification. However, there are certain problems: (1) Cement solidification has a large volume increase, occupying a large amount of land resources, Cr 6+ (1) It is difficult to stabilize metals such as Zn and Zn, and there is still a risk of leaching, and dioxin pollution has not been effectively treated; (2) It is difficult to achieve the stabilization of multiple heavy metals by chemical agents and acid solvent extraction; the stability to dioxins and dissolved salts is weak; (3) The defect of melt solidification is that the presence of Cl in fly ash is easy to corrode refractory materials, and high-temperature treatment has problems such as high energy consumption and large investment. Summary of the invention

[0004] In view of the above analysis, the present invention aims to provide a method for the coordinated treatment of magnesium-based desulfurization wastewater and garbage fly ash, which can at least solve one of the following technical problems: (1) The existing magnesium-based desulfurization wastewater contains excessive amounts of sulfate, suspended solids, chloride, CODcr, fluoride, total mercury, sulfide, total cadmium, total nickel and total zinc; (2) There are many heavy metals in the garbage fly ash, and the dioxin treatment is not thorough, resulting in high energy consumption and large investment; (3) The existing magnesium-based desulfurization wastewater and garbage fly ash are treated separately with a long process flow and high cost.

[0005] The purpose of the present invention is mainly achieved through the following technical solutions:

[0006] The present invention provides a method for co-processing magnesium-based desulfurization wastewater and garbage fly ash, comprising:

[0007] Step 1, mixing garbage fly ash and washed clean coal to obtain a first mixture;

[0008] Step 2, ball-milling the first mixture in step 1, adding magnesium desulfurization wastewater, heavy oil and additives, grinding and slurrying to obtain slurry;

[0009] Step 3: Send the slurry into a waste incineration boiler for combustion.

[0010] Furthermore, in step 1, the mass ratio of garbage fly ash to washed clean coal in the first mixture is 10-20:35-45.

[0011] Furthermore, in step 2, the additive is a mixture of β-naphthalenesulfonic acid formaldehyde condensation product, sodium lignin sulfonate, polyether and polyoxyethylene ether.

[0012] Furthermore, in step 2, in the additive, the weight ratio of β-naphthalenesulfonic acid formaldehyde condensation product, sodium lignin sulfonate, polyether and polyoxyethylene ether is 1:2-3:0.05-0.1:0.05-0.1.

[0013] Furthermore, in step 2, the mass ratio of the first mixture, magnesium desulfurization wastewater, heavy oil and additive is 50-60:30-40:8-15:0.5-1.5.

[0014] Furthermore, in step 2, the calorific value of the slurry is above 14650 KJ / kg.

[0015] Furthermore, in step 3, the slurry is fed into a burner disposed on the waste incineration boiler for combustion, and the burner includes a plurality of combustion-supporting air outlets and a plurality of slurry outlets, and the combustion-supporting air outlets and the slurry outlets are distributed in sequence.

[0016] Furthermore, the size design principle of the combustion air outlet and the slurry outlet is: the ratio of the combustion air to the slurry flow is 350-380:1Nm 3 / m3 Set the outlet size.

[0017] Furthermore, in step 2, the prepared slurry is stored in a slurry tank through a pumping system.

[0018] Furthermore, the components of the garbage fly ash include heavy metal salts, potassium and sodium salts and organic matter.

[0019] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects:

[0020] a) The method for coordinating the treatment of magnesium-based desulfurization wastewater and garbage fly ash of the present invention is to make magnesium-based desulfurization wastewater and garbage fly ash into a flammable liquid similar to water-coal slurry and return it to the garbage incinerator for combustion. During the combustion process, heavy metals are oxidized into stable oxides and discharged with the slag, and the wastewater is discharged as steam, and no liquid wastewater is generated. Some dioxins, organic matter, suspended matter and other substances contained in them are burned and cracked, and some heavy metal elements, unburned and cracked dioxins, etc. enter the dust removal system to become new fly ash for continuous recycling and utilization; the method of the present invention realizes the reduction and harmless treatment of fly ash, and achieves the purpose of coordinating the treatment of the two wastes; it avoids the use of independent long-flow and high-cost treatment processes for both wastes, and realizes the coordinating treatment of the two wastes. Since water is needed in the process of making garbage fly ash into a flammable liquid raw material similar to water-coal slurry and returning it to the incinerator for treatment, and magnesium-based desulfurization wastewater itself must also be treated separately, the present invention combines garbage fly ash and magnesium-based desulfurization wastewater for coordinated treatment, which can also reduce the amount of new water and reduce costs.

[0021] b) The method of the present invention pre-mixes the washed clean coal with the garbage fly ash to increase the calorific value of the first mixture, which is beneficial for the subsequent return to the garbage incineration boiler for combustion treatment; heavy oil is added to the first mixture to increase the calorific value of the slurry and improve the combustibility of the slurry; additives are added to the first mixture to maintain the fluidity and viscosity of the slurry, reduce the precipitation of solid particles, and improve the combustibility of the slurry.

[0022] c) The method of the present invention adopts a special burner with a porous structure, and the combustion air outlet and the slurry outlet are arranged in sequence, which is conducive to the full mixing of the slurry and the combustion air. The combustion air with a high oxygen content is used to make the slurry made of garbage fly ash burn more fully.

[0023] d) The method of the present invention can achieve self-production and self-sales, and treat waste with waste. In the method of the present invention, only the desulfurization wastewater needs to be transported, which is easy to load and unload, and is not easy to spill and cause new pollution, thereby reducing the risk of hazardous waste being scattered during transportation; the undecomposed organic matter in the garbage fly ash contains calorific value, and returning it for combustion increases the heat of the incinerator, increases the power generation of the garbage incinerator, and has higher environmental and social benefits.

[0024] e) The method of the present invention requires little investment and has good treatment effect, can greatly reduce the discharge of two types of wastes, alleviates environmental pressure, and has high economic and social benefits.

[0025] Other features and advantages of the present invention will be described in the following description, and part of them will become obvious from the description, or will be understood by practicing the present invention. The purpose and other advantages of the present invention can be realized and obtained by the written description. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The accompanying drawings are only for the purpose of illustrating the particular invention and are not to be considered as limiting the invention. The same reference symbols denote the same components throughout the accompanying drawings.

[0027] Figure 1 It is a process flow chart of the coordinated treatment method of magnesium-based desulfurization wastewater and garbage fly ash of the present invention;

[0028] Figure 2 It is a structural schematic diagram of the special burner of the present invention;

[0029] Figure 3 This is the process flow chart of the existing magnesium-based desulfurization wastewater treatment process. DETAILED DESCRIPTION

[0030] The following is a further detailed description of a method for the coordinated treatment of magnesium-based desulfurization wastewater and garbage fly ash in conjunction with specific examples. These examples are only used for comparison and explanation purposes, and the present invention is not limited to these examples.

[0031] At present, the amount of wastewater discharged from magnesium desulfurization of sintering flue gas is large, and the sulfate, suspended solids, chloride, CODcr, fluoride, total mercury, sulfide, total cadmium, total nickel and total zinc contained in it exceed the standard. The wastewater after flocculation and precipitation with ordinary reagents is difficult to reach the quality of industrial water. There are many heavy metals in garbage fly ash, and dioxins are generally not completely treated when treated alone (the concentration of dioxins in fly ash is 0.7~5.26ng (I-TEQ).g -1 The "Standards for Pollution Control of Domestic Waste Landfills" revised by the Ministry of Environmental Protection in 2008 stipulates that the dioxin content of fly ash from the incineration of domestic waste must be less than 3ng (I-TEQ).g -1. ), high energy consumption, large investment (the disposal fee of garbage fly ash is now more than 1,000 yuan / ton). These fly ashes are often enriched with a large amount of heavy metals and dioxins. If improperly disposed, they will cause serious harm to human health and the ecological environment. After long-term and in-depth research, the inventor proposed a method for the coordinated treatment of magnesium-based desulfurization wastewater and garbage fly ash. The magnesium-based desulfurization wastewater and garbage fly ash are made into a combustible liquid similar to water-coal slurry and returned to the garbage incinerator for combustion. During the combustion process, heavy metals are oxidized into stable oxides and discharged with the slag, and the wastewater is discharged as steam, without the generation of liquid wastewater; some dioxins, organic matter, suspended matter and other substances contained in the combustible liquid similar to water-coal slurry are burned and cracked, and some heavy metal elements, unburned and cracked dioxins, etc. enter the dust removal system to become new fly ash for continued recycling and utilization; the purpose of coordinated treatment of the two wastes is achieved.

[0032] The present invention provides a method for co-processing magnesium-based desulfurization wastewater and garbage fly ash, comprising:

[0033] Step 1, mixing garbage fly ash and washed clean coal to obtain a first mixture;

[0034] Step 2, feeding the first mixture of step 1 into a ball mill, adding magnesium desulfurization wastewater, heavy oil and additives, and then grinding and slurrying to obtain slurry;

[0035] Step 3: Send the slurry into a special burner installed on the waste incineration boiler for combustion.

[0036] Specifically, in the above step 1, the components of the garbage fly ash include salt from tin cans, zinc batteries, copper materials, residual food, organic potassium fertilizer elements, plastic volatiles, secondary products, etc., that is, heavy metal salts, potassium and sodium salts, organic matter, etc.; illustratively, heavy metal salts include iron salts, lead salts, zinc salts, etc.; potassium and sodium salts include sodium chloride, potassium chloride, etc.; organic matter includes organic potassium fertilizer elements, plastic volatiles, etc.

[0037] For example, the components (mass percentage) of garbage fly ash mainly include: T.Fe: 0.3%-2.0%, FeO: 0.02%-1.0%, CaO: 35%-50%, MgO: 1.0%-5.0%, Al 2 O 3 :1.0%-5.0%, PbO: 1.0%-2.0%, ZnO: 0.01%-1.0%, Na 2 O: 1.0%-5.0%, K 2 O: 2.0%-10.0%, P: <0.08%, S: 0.01%-3.0%, C: 1.0%-5.0%, SiO 2 :2.0%-5.0%, Cl:8.0%-20.0%, TiO 2:0.01%-1.0%; among them, the concentration of dioxins in fly ash is 0.7~5.26ng(I-TEQ).g -1 .

[0038] Specifically, in the above step 1, the calorific value of the first mixture is increased by mixing the washed clean coal with the garbage fly ash, which is beneficial for the subsequent return to the waste incineration boiler for combustion treatment. Considering that too high a content of washed clean coal will cause waste of resources and increase carbon emissions, while too low a content will affect the calorific value and combustibility. Therefore, the mass ratio of garbage fly ash to washed clean coal in the first mixture is controlled to be 10-20:35-45.

[0039] Specifically, in the above step 2, in order to improve efficiency, the first mixture of step 1 can be fed into the ball mill via a belt.

[0040] Specifically, in the above step 2, the magnesium desulfurization wastewater is the wastewater discharged from the sintering process of the ironmaking process using the magnesium desulfurization process; the components of the magnesium desulfurization wastewater mainly include: K + :80-100mg / L, Ca 2+ :800-1200mg / L,Mg 2+ :15-20g / L,Cr 2+ :40-60μg / L, Ni 2+ :40-60μg / L, Zn 2+ :30-40μg / L, Mn 2+ :1-5mg / L, NO 3 - :30-60g / L, NO 2 - :5-20g / L, SO 4 2- :70-95g / L, Cl - :20-40g / L,Cu 2+ :10-30μg / L, Pb 2+ :<5μg / L, As:10-30μg / L, Se:100-200μg / L, chemical oxygen demand 310-350mg / L, suspended matter 20-30g / L, ammonia nitrogen 200-230mg / L, solid content 5%-9%, total hardness 23-26g / L.

[0041] Specifically, in the above step 2, the role of adding heavy oil to the first mixture is to increase the calorific value of the slurry and improve the combustibility of the slurry; the role of adding additives to the first mixture is to keep the fluidity and viscosity of the slurry and reduce the precipitation of solid particles; because water is needed in the process of making garbage fly ash into a water-coal slurry-like raw material and returning it to the incinerator for treatment, and the magnesium-based desulfurization wastewater itself must be treated separately, the present invention replaces the new water with the magnesium-based desulfurization wastewater, and combines the garbage fly ash and the magnesium-based desulfurization wastewater for coordinated treatment, which can reduce the amount of new water used and reduce costs.

[0042] Specifically, in the above step 2, in order to maintain the fluidity and viscosity of the slurry, the additive may be a mixture of β-naphthalenesulfonic acid formaldehyde condensate, sodium lignin sulfonate, polyether and polyoxyethylene ether.

[0043] Specifically, in the above step 2, the weight ratio of β-naphthalenesulfonic acid formaldehyde condensation product, sodium lignin sulfonate, polyether and polyoxyethylene ether in the additive is 1:2-3:0.05-0.1:0.05-0.1.

[0044] Specifically, in the above step 2, considering that the content of magnesium desulfurization wastewater is too high to reduce the calorific value and cannot be burned, too low to achieve the purpose of wastewater treatment; too high heavy oil content increases the cost, too low to reduce the calorific value; too high additive content is too thick and has poor fluidity. Therefore, the mass ratio of the first mixture, magnesium desulfurization wastewater, heavy oil and additive is controlled to be 50-60:30-40:8-15:0.5-1.5.

[0045] Specifically, in the above step 2, the calorific value of the slurry is above 14650 KJ / kg (3500 kcal / kg).

[0046] Specifically, in the above step 2, the prepared slurry can be stored in a slurry tank through a pumping system.

[0047] Specifically, in the above step 3, the slurry can be sent to a special burner arranged on the waste incineration boiler through a pipeline by a screw pump for combustion.

[0048] Specifically, in the above step 3, the waste incineration boiler is a chain furnace or a grate furnace, and a special burner is set in the high temperature section of the incineration boiler; because the slurry has a certain calorific value, the slurry can be directly ignited in the high temperature section of the waste incineration boiler by passing it into the waste incineration boiler.

[0049] Specifically, in the above step 3, the special burner is a porous structure, such as Figure 2As shown, the special burner includes multiple combustion air outlets and multiple slurry outlets, and the combustion air outlets and the slurry outlets are distributed in sequence. For example, multiple combustion air outlets are evenly distributed in the circumference of more than two concentric circles, and multiple slurry outlets are evenly distributed in the circumference of at least one concentric circle. The slurry outlet is distributed at the center of the concentric circle. In the radial direction, the combustion air outlet and the slurry outlet are alternately distributed. The combustion air outlet is surrounded by the slurry outlet, and the slurry outlet is surrounded by the combustion air outlet. The ratio of the combustion air to slurry flow rate is 350-380:1Nm 3 / m 3 The outlet size is set to ensure full combustion and the oxygen content in the combustion-supporting air is above 80%. The combustion-supporting air outlet and the slurry outlet are arranged in sequence, which is conducive to the full mixing of the slurry and the combustion-supporting air. The combustion-supporting air with a higher oxygen content makes the slurry made of garbage fly ash burn more fully.

[0050] Specifically, a first slurry outlet is arranged at the center of the burner, and a plurality of first combustion-supporting air outlets are arranged around the first slurry outlet, the plurality of first combustion-supporting air outlets have the same size, and the center of each first combustion-supporting air outlet is located on the concentric circle of the first slurry outlet; a plurality of second slurry outlets are arranged around the first combustion-supporting air outlet, the plurality of second slurry outlets have the same size, and the center of each second slurry outlet is located on the concentric circle of the first slurry outlet; a plurality of second combustion-supporting air outlets are arranged around the second slurry outlet, the plurality of second combustion-supporting air outlets have the same size, and the center of each second combustion-supporting air outlet is located on the concentric circle of the first slurry outlet. In other words, a first slurry outlet is arranged at the center of the burner, and a circle (plurality) of first combustion-supporting air outlets are arranged around the first slurry outlet, a circle of second slurry outlets are arranged around a circle of first combustion-supporting air outlets, and a circle of second combustion-supporting air outlets are arranged around a circle of second slurry outlets.

[0051] Specifically, in the above step 3, water undergoes the following water-gas reaction:

[0052] C+H 2 O=H 2 +CO;CO+H 2 O=H 2 +CO 2 ;

[0053] Heavy metals are oxidized into stable oxides and discharged with the slag. After the above cycle, the composition of the gas emissions after combustion is SO 2 The content is about 20mg / Nm 3 , NOx content is about 30mg / Nm 3 , PM content is about 10mg / Nm 3 . As attached Figure 3As shown, the existing magnesium-based desulfurization wastewater treatment process is long. For example, in CN201510483875.6, it at least includes aeration treatment of desulfurization wastewater, adjusting the pH value of desulfurization wastewater to 10, adding phosphate and zeolite powder to the desulfurization wastewater to remove ammonia nitrogen, adding lime and iron salt to the desulfurization wastewater to remove organic matter, chromaticity, phosphate, fluoride, and heavy metals produced by coal combustion, and adjusting the pH of desulfurization wastewater to 7. The existing hazardous waste disposal fee of garbage fly ash now exceeds 1,000 yuan / ton. Garbage fly ash mostly uses high-temperature melting oxidation of heavy metal ions and other methods, which requires separate treatment equipment and may cause new pollution. Compared with the prior art, the method for coordinating the treatment of magnesium-based desulfurization wastewater and garbage fly ash of the present invention prepares the magnesium-based desulfurization wastewater and garbage fly ash into a flammable liquid similar to water-coal slurry and returns the flammable liquid to the garbage incinerator for combustion. During the combustion process, organic matter, carbon, heavy oil and additives in the slurry are burned and oxidized into carbon dioxide and water vapor under the condition of high-temperature oxygen combustion in the furnace and discharged through the dust removal system. Part of dioxins are burned and cracked, and most of the heavy metal elements in the magnesium-based desulfurization wastewater and garbage fly ash of the sintering flue gas are oxidized into stable oxides and enter the slag and are discharged through the slag treatment system. The slag can be used as cement, roadbed or other building materials, and some heavy metal elements, unburned and cracked dioxins, etc. enter the dust removal system to become new fly ash for continuous recycling. The method of the present invention simultaneously realizes the reduction and harmless treatment of magnesium-based desulfurization wastewater and garbage fly ash, and achieves the purpose of coordinating the treatment of the two wastes. It avoids the long process and high cost of treating the two wastes separately, and realizes the coordinating treatment of the two wastes.

[0054] The method of the present invention pre-mixes washed clean coal with garbage fly ash to increase the calorific value of the first mixture, which is beneficial for the subsequent return to the garbage incineration boiler for combustion treatment; heavy oil is added to the first mixture to increase the calorific value of the slurry and improve the combustibility of the slurry; additives are added to the first mixture to keep the fluidity and viscosity of the slurry, reduce the precipitation of solid particles, and improve the combustibility of the slurry.

[0055] The method of the present invention adopts a special burner with a porous structure. The combustion air outlet and the slurry outlet are arranged in sequence, which is conducive to the full mixing of the slurry and the combustion air. The combustion air with a high oxygen content is used to make the slurry made of garbage fly ash burn more fully.

[0056] The method of the present invention can realize self-production and self-sale, and treat waste with waste, thereby reducing the risk of scattering of hazardous waste during transportation. At the same time, slurry combustion increases the power generation of the garbage incinerator, which has high environmental and social benefits.

[0057] The method of the invention requires little investment and has good treatment effect, can greatly reduce the discharge of two kinds of wastes, alleviates environmental pressure, and has high economic and social benefits.

[0058] Example 1

[0059] This embodiment provides a method for the coordinated treatment of magnesium-based desulfurization wastewater and garbage fly ash. 2 The main components of the magnesium-based desulfurization wastewater from sintering flue gas of the sintering machine are shown in Table 1, and the main element components of the fly ash are shown in Table 2.

[0060] Table 1 Main components and contents of magnesium desulfurization wastewater

[0061]

[0062] Table 2 Main element composition of garbage fly ash (mass percentage %)

[0063] Element TFe FeO CaO MgO <![CDATA[Al 2 THE 3 ]]> PbO ZnO <![CDATA[Na 2 The]]> <![CDATA[K 2 The]]> P S content 0.78 0.09 42.88 3.16 1.69 1.47 0.06 3.87 4.63 0.05 1.98 Element C <![CDATA[SiO 2 ]]> Cl <![CDATA[TiO 2 ]]> content 3.44 3.66 12.46 0.41

[0064] The coordinated treatment method of magnesium desulfurization wastewater and garbage fly ash in this implementation case is as follows: Figure 1 As shown, follow these steps:

[0065] (1) The fly ash produced as a byproduct of a municipal solid waste incineration power plant in the steel plant is mixed with clean coal to obtain a first mixture, wherein the mass ratio of the fly ash to the clean coal is 10:45; the calorific value of the fly ash is 1170 KJ / kg (280 kcal / kg), the calorific value of the clean coal is 26344 KJ / kg (6300 kcal / kg), and the calorific value of the first mixture is 21758 KJ / kg (5200 kcal / kg);

[0066] (2) The first mixture of step (1) is conveyed to a ball mill through a belt for grinding and pulping, and 34% by weight of sintering flue gas magnesium desulfurization wastewater, 10% of heavy oil and 1% of additives are added to form a finished slurry; the additive component ratio is: a mixture of β-naphthalenesulfonic acid formaldehyde condensation product, sodium lignin sulfonate, polyether and polyoxyethylene ether in a weight ratio of 1:2:0.1:0.1. The calorific value of the slurry obtained by grinding is 16189KJ / kg (3869kcal / kg);

[0067] (3) storing the finished slurry obtained by grinding in step (2) in a slurry tank through a pumping system;

[0068] (4) The slurry is sent to a special burner with a porous structure installed in the high-temperature section of the garbage incineration chain furnace boiler through a screw pump through a pipeline for combustion. The burner uses combustion air containing 80% oxygen. The oxygen outlet and the slurry outlet are adjacent to each other. The oxygen outlet is surrounded by the slurry outlet, and the slurry outlet is surrounded by the oxygen outlet. The oxygen and slurry flow ratio is 350:1Nm 3 / m 3 Set the outlet size.

[0069] During the combustion process of the garbage fly ash slurry made from the sintering flue gas magnesium method desulfurization wastewater, the organic matter, carbon, heavy oil and additives in the slurry are burned and oxidized into carbon dioxide and water vapor under the high-temperature oxygen combustion conditions in the furnace and discharged through the dust removal system. Part of the dioxins are burned and cracked, and most of the heavy metal elements in the sintering flue gas magnesium method desulfurization wastewater and garbage fly ash are oxidized into stable oxides and enter the slag and are discharged through the slag treatment system of the grate furnace. They are used as cement, roadbed or other construction materials, and some enter the dust removal system to become new fly ash for continuous recycling. After the above cycle, the composition of the gas emissions after combustion is SO 2 The content is about 20mg / Nm 3 , NOx content is about 30mg / Nm 3 , PM content is about 10mg / Nm 3 .

[0070] In the prior art, garbage fly ash is a hazardous waste, and the disposal fee is now more than 1,000 yuan / ton. The method of the present invention only requires simple pulping and returning for combustion, which increases power generation, reduces the amount of hazardous waste treatment, and reduces costs by more than 60%. Magnesium desulfurization wastewater does not need to be treated separately, and garbage fly ash does not need to be shipped out of the factory. The method of the present invention has low investment and good treatment effect.

[0071] Example 2

[0072] This embodiment provides a method for the coordinated treatment of magnesium-based desulfurization wastewater and garbage fly ash. 2 The main components of the magnesium-based desulfurization wastewater from sintering flue gas of the sintering machine, the magnesium-based desulfurization wastewater and the garbage fly ash are the same as those in Example 1. Follow the following steps:

[0073] (1) The waste incineration fly ash produced as a byproduct of the municipal solid waste incineration power plant where the steel plant is located is stirred and mixed with the washed clean coal to obtain a first mixture, wherein the mass ratio of the waste fly ash to the washed clean coal is 20:35; the calorific value of the waste fly ash is 3344 KJ / kg, the calorific value of the washed clean coal is 27170 KJ / kg, and the calorific value after mixing is 18506 KJ / kg;

[0074] (2) The first mixture of step (1) is conveyed to a ball mill through a belt for grinding and pulping, and 34% by weight of sintering flue gas magnesium desulfurization wastewater, 10% of heavy oil and 1% of additives are added to form a finished slurry; the additive component ratio is: a mixture of β-naphthalenesulfonic acid formaldehyde condensation product, sodium lignin sulfonate, polyether and polyoxyethylene ether in a weight ratio of 1:3:0.05:0.05. The calorific value of the slurry obtained by grinding is 14646KJ / kg;

[0075] (3) storing the finished slurry obtained by grinding in step (2) in a slurry tank through a pumping system;

[0076] (4) The slurry is sent to a special burner with a porous structure installed in the high-temperature section of the garbage incineration chain furnace boiler through a screw pump through a pipeline for combustion. The burner uses combustion air containing 85% oxygen. The oxygen outlet and the slurry outlet are adjacent to each other. The oxygen outlet is surrounded by the slurry outlet, and the slurry outlet is surrounded by the oxygen outlet. The oxygen and slurry flow ratio is 380:1Nm 3 / m 3 Set the outlet size.

[0077] During the combustion process of the garbage fly ash slurry made from the wastewater from the sintering flue gas magnesium desulfurization process, the organic matter, carbon, heavy oil and additives in the slurry are burned and oxidized into carbon dioxide and water vapor under the high-temperature oxygen combustion-assisted conditions in the furnace and discharged through the dust removal system. Part of the dioxins are burned and cracked, and most of the heavy metal elements in the wastewater and fly ash from the sintering flue gas magnesium desulfurization process are oxidized into stable oxides and enter the slag and are discharged through the slag treatment system of the grate furnace to be used as cement, roadbed or other construction materials. Another part enters the dust removal system to become new fly ash for continuous recycling. After the above cycle, the composition of the gas emissions after combustion is SO 2 The content is about 20mg / Nm 3 , NOx content is about 30mg / Nm 3 , PM content is about 10mg / Nm 3 .

[0078] The method of the invention has low investment and good treatment effect.

[0079] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by any technician familiar with the technical field within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention.

Claims

1. A method for the coordinated treatment of magnesium-based desulfurization wastewater and garbage fly ash, characterized in that: include: Step 1, mixing garbage fly ash and washed clean coal to obtain a first mixture; the mass ratio of garbage fly ash to washed clean coal in the first mixture is 10-20:35-45; Step 2, after ball-milling the first mixture in step 1, adding magnesium desulfurization wastewater, heavy oil and additives to pulp to obtain slurry; the additive is a mixture of β-naphthalenesulfonic acid formaldehyde condensate, sodium lignin sulfonate, polyether and polyoxyethylene ether; the mass ratio of the first mixture, magnesium desulfurization wastewater, heavy oil and additive is 50-60:30-40:8-15:0.5-1.5; Step 3, sending the slurry into a waste incineration boiler for combustion; In the step 3, the slurry is fed into a burner arranged on the waste incineration boiler for combustion, the burner includes a plurality of combustion-supporting air outlets and a plurality of slurry outlets, and the combustion-supporting air outlets and the slurry outlets are distributed in sequence; a first slurry outlet is arranged at the center of the burner, and a plurality of first combustion-supporting air outlets are arranged around the first slurry outlet, the plurality of first combustion-supporting air outlets have the same size, and the center of each first combustion-supporting air outlet is located on a concentric circle of the first slurry outlet; a plurality of second slurry outlets are arranged around the first combustion-supporting air outlet, the plurality of second slurry outlets have the same size, and the center of each second slurry outlet is located on a concentric circle of the first slurry outlet; a plurality of second combustion-supporting air outlets are arranged around the second slurry outlet, the plurality of second combustion-supporting air outlets have the same size, and the center of each second combustion-supporting air outlet is located on a concentric circle of the first slurry outlet.

2. The method for co-processing magnesium desulfurization wastewater and garbage fly ash according to claim 1, characterized in that: In the step 2, in the additive, the weight ratio of β-naphthalenesulfonic acid formaldehyde condensation product, sodium lignin sulfonate, polyether and polyoxyethylene ether is 1:2-3:0.05-0.1:0.05-0.

1.

3. The method for co-processing magnesium-based desulfurization wastewater and garbage fly ash according to claim 1, characterized in that: In step 2, the calorific value of the slurry is above 14650 KJ / kg.

4. The method for co-processing magnesium-based desulfurization wastewater and garbage fly ash according to claim 1, characterized in that: The size design principle of the combustion air outlet and the slurry outlet is: the ratio of the combustion air to the slurry flow is 350~380:1Nm 3 / m 3 Set the outlet size.

5. The method for co-processing magnesium-based desulfurization wastewater and garbage fly ash according to claim 1, characterized in that: In step 2, the prepared slurry is stored in a slurry tank through a pumping system.

6. The method for co-processing magnesium-based desulfurization wastewater and garbage fly ash according to any one of claims 1 to 5, characterized in that: The components of the garbage fly ash include heavy metal salts, potassium and sodium salts and organic matter.

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