Synergistic treatment method of baking soda desulfurization ash and waste iron oxide desulfurizer

Abstract

The invention discloses a method for collaboratively treating baking soda desulfurization ash and waste iron oxide desulfurizer. The method comprises the following steps: placing baking soda desulfurization ash in a stirring tank, adding water at a water-ash ratio of (3-5):1, and stirring the mixture into fluidized slurry; uniformly mixing the waste iron oxide desulfurizer and coal at a mass ratio of (1-5):1000, and grinding the mixture with steel balls to obtain a mixed fuel; atomizing the slurry at a fuel delivery port of a pulverized coal boiler, blending the mixture with the mixed fuel, and then feeding the mixture into a furnace for combustion; volatile matter is purified by a terminal gas purification device to generate desulfurization gypsum, and ash is mixed with fly ash and bottom ash. The method reasonably configures the addition amounts of the waste iron oxide desulfurizer and the baking soda desulfurization ash, thereby ensuring that the discharged flue gas meets the ultra-low emission environmental protection requirement, and the ash mixed with the fly ash and bottom ash meets the environmental protection requirement.

Description

Technical Field

[0001] The invention belongs to the technical field of solid waste treatment, and particularly relates to a method for collaboratively treating baking soda desulfurization ash and waste iron oxide desulfurizer. Background Art

[0002] Iron oxide desulfurizer is a highly effective gas purifier made with iron oxide as its primary active ingredient and other additives. Within the temperature range of 20°C to 100°C, it has high H2S removal performance, while also having a certain degree of removal effect on mercaptans, organic sulfur compounds, and most nitrogen oxides. After the reaction, the waste iron oxide desulfurizer contains large amounts of harmful organic compounds such as naphthalene, benzene, and tar. Its main components also include inorganic compounds such as elemental sulfur, FeS, and Fe2S3. This hazardous waste, if randomly dumped, not only pollutes the environment but also poses significant safety risks, potentially causing explosions, fires, and other accidents.

[0003] Baking soda desulfurization ash is a byproduct of the sodium-based desulfurization process. This process uses baking soda as a desulfurizer. It is ground into an ultrafine powder in a mill and sprayed into high-temperature flue gas, where it comes into contact with the flue gas, undergoing physical and chemical reactions with acidic gases such as SO2, HCl, and HF, effectively removing the gases. The baking soda desulfurization ash collected by the bag filter is primarily composed of Na2SO4, incompletely oxidized Na2SO3, and a small amount of unreacted NaHCO3.

[0004] Currently, the main methods for disposing of spent iron oxide desulfurizers are landfill and return to the desulfurizer manufacturer. Landfilling can pollute the surrounding environment and soil, while return to the desulfurizer manufacturer not only faces high disposal fees of 5,000-8,000 yuan per ton, but also presents significant uncontrollable risks after solid waste transfer. Regarding the utilization of baking soda desulfurization ash, due to the short application time and small production volume of this process, a large-scale resource utilization approach has yet to be established. Given the chemical composition of baking soda desulfurization ash, its resource utilization is primarily hindered by the presence of a certain amount of Na2SO3. While Na2SO3 has been reported in the literature, it is primarily used for treating hexavalent chromium, mineral processing, and wastewater treatment, but high-temperature incineration is not an option. Summary of the Invention

[0005] The purpose of the present invention is to provide a method for the synergistic treatment of baking soda desulfurization ash and waste iron oxide desulfurizer, utilizing the coal-fired boiler of a self-contained power plant and its supporting desulfurization and denitrification facilities, combining the characteristics of the two solid wastes, and treating them in a comprehensive resource-based manner, thereby conveniently and cheaply solving the problem of difficult disposal of large amounts of metallurgical solid waste accumulation.

[0006] In order to achieve the above purpose, the technical solutions adopted are as follows:

[0007] The method for collaboratively treating baking soda desulfurization ash and waste iron oxide desulfurizer comprises the following steps:

[0008] (1) Baking soda desulfurization ash is placed in a mixing tank, and water is added according to a water-ash ratio of (3-5):1 to stir into a fluidized slurry; waste iron oxide desulfurizer and coal are mixed uniformly at a mass ratio of (1-5):1000, and the mixed fuel is obtained after grinding with steel balls;

[0009] (2) atomizing the slurry at a fuel delivery port of a pulverized coal boiler, mixing the slurry with the mixed fuel, and then feeding the mixed fuel into a furnace for combustion;

[0010] (3) The volatile matter is purified by the terminal gas purification device to generate desulfurization gypsum, and the ash is mixed with fly ash and bottom ash.

[0011] According to the above scheme, the baking soda desulfurization ash is a particle with a size of less than 200 mesh (75 μm); the main chemical components include: 30-60% Na2SO4, 10-20% Na2SO3, 20-60% NaHCO3, 0-1% NaCl, and 0-1% NaNO3.

[0012] According to the above scheme, the waste iron oxide desulfurizer is 0-5mm particles; the main chemical components include: 45%-60% FeS, 10%-25% Fe2O3, 10%-15% CaO, 5%-10% C, and 5%-15% metal oxides (including Al2O3 and MgO).

[0013] According to the above scheme, in step 1, the waste iron oxide desulfurizer is evenly mixed with the coal and then spread on the feed belt and sent to the pulverizing system for grinding with steel balls to obtain the mixed fuel.

[0014] According to the above scheme, the mud described in step 2 is delivered to the fuel delivery port through the sludge delivery pipe under the action of the high-pressure mud pump. The fuel delivery port is equipped with a special atomizing nozzle for mud two-phase flow, which atomizes the mud and mixes it into the mixed fuel.

[0015] According to the above scheme, in step 2, the mass ratio of baking soda desulfurization ash to waste iron oxide desulfurizer is 1:(2-5) and completely burned in a pulverized coal boiler.

[0016] According to the above scheme, in step 2, the temperature inside the pulverized coal boiler is controlled at 1250-1400°C, the flue gas residence time is 5s, the solid phase residence time is 5s, and the furnace outlet temperature is higher than 900°C.

[0017] According to the above scheme, the gas purification device in step 3 is a limestone-gypsum wet desulfurization + SCR denitrification process.

[0018] Compared with the prior art, the present invention has the following positive effects:

[0019] (1) To ensure a relatively stable and low-cost electricity supply, large industrial enterprises have mostly invested in self-owned power plants and established corresponding environmental protection facilities such as desulfurization and denitrification in accordance with relevant national regulations. They have reserved a certain amount of processing capacity and have the ability to co-dispose of high-sulfur substances. This makes up for the environmental problem of excessive flue gas emissions caused by the insufficient flue gas purification capacity of ordinary incinerators to dispose of high-sulfur solid waste. The present invention uses a process method for co-disposal of waste iron oxide desulfurizers with power plants. This method has the characteristics of comprehensive pollutant treatment and large disposal capacity, and has good technical and economic benefits.

[0020] (2) The reaction temperature in the pulverized coal boiler is above 1250℃, which can fully burn the organic hazardous components such as tar, naphthalene, benzene, CnHm, HCN, etc. adsorbed by the waste iron oxide desulfurizer, and finally generate CO2 which is discharged into the atmosphere with the flue gas, which can solve the problem of organic pollution in the desulfurizer.

[0021] (3) Compared with the combustion temperature of only 900℃ in solid waste and garbage treatment furnaces such as garbage incinerators, the gas phase temperature in the furnace is above 1250℃, and the gas residence time is as long as 5s. In addition, research has shown that the sulfur contained in the fuel has a certain inhibitory effect on the formation of dioxins. Therefore, the sulfur in the waste iron oxide desulfurizer can inhibit the chlorine introduced by the baking soda desulfurization ash, thereby avoiding the formation of dioxins. The iron in the waste iron oxide desulfurizer can also react with the alkali metal in the baking soda desulfurization ash, thereby preventing the corrosion of the furnace lining during the baking soda desulfurization ash co-combustion process.

[0022] (4) The combined synergistic treatment of baking soda desulfurization ash and waste iron oxide desulfurizer can effectively eliminate its pollution hazards to the environment without adding other additional equipment, and can recover the C and S elements therein, thereby obtaining better economic benefits. The present invention can make the exhaust flue gas meet the ultra-low emission environmental protection requirements by reasonably configuring the addition amount of waste iron oxide desulfurizer and baking soda desulfurization ash, and the ash mixed with fly ash and bottom ash emissions can meet environmental protection requirements. However, if the addition amount of waste iron oxide desulfurizer exceeds the scope of the present invention, the outlet tail gas emissions will not meet the standards, and if the addition amount of baking soda desulfurization ash exceeds the scope of the present invention, it will cause corrosion to the boiler. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 : Flow chart of the collaborative treatment process of baking soda desulfurization ash and waste iron oxide desulfurizer of the present invention. DETAILED DESCRIPTION

[0024] The following examples further illustrate the technical solutions of the present invention but are not intended to limit the scope of protection of the present invention.

[0025] The specific embodiment provides a method for co-processing baking soda desulfurization ash and waste iron oxide desulfurizer, Figure 1 As shown:

[0026] (1) Baking soda desulfurization ash is placed in a mixing tank, and water is added according to a water-ash ratio of (3-5):1 to form a fluidized slurry; waste iron oxide desulfurizer and coal are mixed evenly at a mass ratio of (1-5):1000, spread on a feed belt, and sent to a pulverizing system for grinding with steel balls to obtain a mixed fuel;

[0027] (2) atomizing the slurry at a fuel delivery port of a pulverized coal boiler, mixing the slurry with the mixed fuel, and then feeding the mixed fuel into a furnace for combustion;

[0028] (3) The volatile matter is purified by the terminal gas purification device to generate desulfurization gypsum, and the ash is mixed with fly ash and bottom ash.

[0029] Specifically, baking soda desulfurization ash is a particle with a size of less than 200 mesh (75 μm); its main chemical components include: 30-60% Na2SO4, 10-20% Na2SO3, 20-60% NaHCO3, 0-1% NaCl, and 0-1% NaNO3.

[0030] Specifically, the waste iron oxide desulfurizer is 0-5 mm particles; the main chemical components include: 45%-60% FeS, 10%-25% Fe2O3, 10%-15% CaO, 5%-10% C, and 5%-15% metal oxides (including Al2O3 and MgO).

[0031] Specifically, the mud in step 2 is delivered to the fuel delivery port through the sludge delivery pipe under the action of a high-pressure mud pump. The fuel delivery port is equipped with a special atomizing nozzle for mud two-phase flow, which atomizes the mud and then mixes it into the mixed fuel.

[0032] Specifically, in step 2, the baking soda desulfurization ash and the waste iron oxide desulfurizer are completely burned in a pulverized coal boiler at a mass ratio of 1:(2-5).

[0033] Specifically, in step 2, the temperature in the pulverized coal boiler is controlled at 1250-1400°C, the flue gas residence time is 5s, the solid phase residence time is 5s, and the furnace outlet temperature is higher than 900°C.

[0034] Specifically, the gas purification device in step 3 is a limestone-gypsum wet desulfurization + SCR denitrification process.

[0035] Example 1

[0036] 1) Place baking soda desulfurization ash with a chemical composition of 60% Na2SO4, 18% Na2SO3, 20% NaHCO3, 1% NaCl, and 1% NaNO3 in a mixing tank, add an appropriate amount of pure water according to a water-cement ratio of 3:1, and stir into fluidized mud. Then, under the action of a high-pressure mud pump, send it to the fuel delivery port through the sludge delivery pipe. The fuel delivery port is equipped with a special atomizing nozzle for mud two-phase flow. The mud is atomized and mixed into the fuel and sent to the furnace for incineration.

[0037] 2) Use a forklift to mix the waste iron oxide desulfurizer with a chemical composition of 60% FeS, 20% Fe2O3, 10% CaO, 5% C and 5% of a small amount of Al2O3, MgO and other metal oxides with coal at a mass ratio of 5:1000. After mixing, the whole mixture should be uniform without visible agglomerates, lumps, or interlayers. Then spread the mixture evenly on the feed belt and send it to the pulverizing system for grinding with steel balls and then sent to the furnace for incineration.

[0038] 3) The baking soda desulfurization ash and the waste iron oxide desulfurizer are completely burned in the boiler at a mass ratio of 1:5. The temperature in the pulverized coal boiler is controlled at 1300°C, the flue gas residence time is 5s, the solid phase residence time is 5s, and the furnace outlet temperature is 950°C. The volatile matter is purified by the terminal gas purification device to generate desulfurization gypsum, and the ash is mixed with fly ash and bottom ash. The emissions meet environmental protection requirements, and all by-products are sold outside.

[0039] Example 2:

[0040] 1) Place baking soda desulfurization ash with a chemical composition of 30% Na2SO4, 10% Na2SO3, 59% NaHCO3, 0.5% NaCl, and 0.5% NaNO3 in a mixing tank, add an appropriate amount of pure water according to a water-cement ratio of 4:1, and stir it into fluidized mud. Then, under the action of a high-pressure mud pump, send it to the fuel delivery port through the sludge delivery pipe. The fuel delivery port is equipped with a special atomizing nozzle for mud two-phase flow. The mud is atomized and mixed with the fuel and sent to the furnace for incineration.

[0041] 2) Use a forklift to mix the waste iron oxide desulfurizer with a chemical composition of 50% FeS, 10% Fe2O3, 15% CaO, 10% C and 15% of a small amount of metal oxides such as Al2O3 and MgO with the coal at a mass ratio of 3:1000. After mixing, the whole mixture should be uniform without visible agglomerates, lumps, or interlayers. Then spread the mixture evenly on the feed belt and send it to the pulverizing system for grinding with steel balls and then sent to the furnace for incineration.

[0042] 3) The baking soda desulfurization ash and the waste iron oxide desulfurizer are completely burned in the boiler at a mass ratio of 1:3. The temperature in the pulverized coal boiler is controlled at 1250°C, the flue gas residence time is 5s, the solid phase residence time is 5s, and the furnace outlet temperature is 910°C. The volatile matter is purified by the terminal gas purification device to generate desulfurization gypsum, and the ash is mixed with fly ash and bottom ash. The emissions meet environmental protection requirements, and all by-products are sold out.

[0043] Example 3:

[0044] 1) Place baking soda desulfurization ash with a chemical composition of 40% Na2SO4, 15% Na2SO3, and 45% NaHCO3 in a mixing tank, add an appropriate amount of pure water according to a water-cement ratio of 5:1, and stir it into fluidized mud. Then, under the action of a high-pressure mud pump, send it to the fuel delivery port through the sludge delivery pipe. The fuel delivery port is equipped with a special atomizing nozzle for mud two-phase flow. The mud is atomized and mixed with the fuel and sent to the furnace for incineration.

[0045] 2) Use a forklift to mix the waste iron oxide desulfurizer with a chemical composition of 45% FeS, 25% Fe2O3, 12% CaO, 8% C and 10% of a small amount of metal oxides such as Al2O3 and MgO with the coal at a mass ratio of 1:1000. After mixing, the whole mixture should be uniform without visible agglomerates, lumps, or interlayers. Then spread the mixture evenly on the feed belt and send it to the pulverizing system for grinding with steel balls and then sent to the furnace for incineration.

[0046] 3) The baking soda desulfurization ash and the waste iron oxide desulfurizer are completely burned in the boiler at a mass ratio of 1:2. The temperature in the pulverized coal boiler is controlled at 1400°C, the flue gas residence time is 5s, the solid phase residence time is 5s, and the furnace outlet temperature is 930°C. The volatile matter is purified by the terminal gas purification device to generate desulfurization gypsum, and the ash is mixed with fly ash and bottom ash. The emissions meet environmental protection requirements, and all by-products are sold out.

[0047] Test results of heavy metal toxicity leaching of fly ash and desulfurization gypsum:

[0048] In accordance with the requirements of GB5085.3-2007 Hazardous Waste Identification Standard - Leaching Toxicity Identification, the desulfurized gypsum and fly ash solids obtained by burning desulfurized ash mixed with baking soda and waste iron oxide desulfurizer were pretreated to prepare toxic leachates. The toxic leachates of fly ash and desulfurized gypsum were then analyzed according to QSH003-2018 inductively coupled plasma emission spectrometry. The results are shown in Table 1.

[0049] Table 1

[0050]

[0051]

[0052] The test results show that the ash after high-temperature combustion of waste iron oxide desulfurizer has no negative impact on desulfurization gypsum, fly ash and slag, and there is no environmental risk and it can be taken out normally.

Claims

1. A method for synergistically treating baking soda desulfurization ash and waste iron oxide desulfurizer, characterized in that The steps include: (1) Baking soda desulfurization ash is placed in a mixing tank, and water is added according to a water-ash ratio of (3-5):1 to form a fluidized slurry; the waste iron oxide desulfurizer and coal are mixed uniformly at a mass ratio of (1-5):1000, and a mixed fuel is obtained after grinding with a steel ball; the baking soda desulfurization ash is a particle with a size of less than 200 mesh; the main chemical components include: 30-60% Na2SO4, 10-20% Na2SO3, 20-60% NaHCO3, 0-1% NaCl, 0-1% NaNO3; the waste iron oxide desulfurizer is a particle with a size of 0-5mm; the main chemical components include: 45%-60% FeS, 10%-25% Fe2O3, 10%-15% CaO, 5%-10% C, and 5%-15% metal oxides; (2) The slurry is atomized and mixed with the mixed fuel at the fuel delivery port of the pulverized coal boiler, and then fed into the furnace for combustion; the temperature in the pulverized coal boiler is controlled at 1250-1400°C, the flue gas residence time is 5 seconds, the solid phase residence time is 5 seconds, and the furnace outlet temperature is higher than 900°C; (3) The volatile matter is purified by the terminal gas purification device to generate desulfurization gypsum, and the ash is mixed with fly ash and bottom ash.

2. The method for collaboratively treating baking soda desulfurization ash and waste iron oxide desulfurizer as claimed in claim 1, characterized in that In step 1, the waste iron oxide desulfurizer is evenly mixed with the coal and then spread on the feed belt and sent to the pulverizing system for grinding with steel balls to obtain the mixed fuel.

3. The method for collaboratively treating baking soda desulfurization ash and waste iron oxide desulfurizer as claimed in claim 1, characterized in that The mud in step 2 is delivered to the fuel delivery port through the sludge delivery pipe under the action of a high-pressure mud pump. The fuel delivery port is equipped with a special atomizing nozzle for mud two-phase flow, which atomizes the mud and then mixes it into the mixed fuel.

4. The method for synergistically treating baking soda desulfurization ash and waste iron oxide desulfurizer as claimed in claim 1, characterized in that In step 2, the baking soda desulfurization ash and the waste iron oxide desulfurizer are completely burned in a pulverized coal boiler at a mass ratio of 1: (2-5).

5. The method for synergistically treating baking soda desulfurization ash and waste iron oxide desulfurizer as claimed in claim 1, characterized in that The gas purification device in step 3 is a limestone-gypsum wet desulfurization + SCR denitrification process.

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