Treatment methods for desulfurization ash in semi-dry sintering flue gas desulfurization processes

Abstract

This invention provides a method for treating desulfurization ash from a semi-dry sintering flue gas desulfurization process. The desulfurization ash from the semi-dry sintering flue gas desulfurization process is pre-mixed evenly with dolomite powder, and then added to a blended ore for secondary mixing. This ensures more uniform mixing of the desulfurization ash during sintering, with the desulfurization ash and dolomite powder mutually coating each other. After sintering, the granulation and mixing are uniform, preventing the desulfurization ash from being removed during subsequent sintering. This ensures that the amount of flux in the material layer, i.e., the amount of liquid phase, is not reduced, thus guaranteeing the strength of the sintered ore. This invention can consume the desulfurization ash from the semi-dry sintering flue gas desulfurization process, utilizing its high calcium content to act as a flux substitute, reducing flux consumption, stabilizing the sintering process, and obtaining qualified sintered ore with the required chemical composition after sintering. This meets the needs of blast furnace production, protects the environment, saves resources, and reduces the economic burden on enterprises.

Description

Technical Field

[0001] This invention belongs to the field of chemical manufacturing technology and relates to a method for treating desulfurization ash. Background Technology

[0002] Desulfurization ash is a solid waste produced by semi-dry and dry flue gas desulfurization, while sintering flue gas desulfurization ash is a particulate mixture produced after sintering flue gas reacts with desulfurizing agent and is separated by a cyclone separator or bag filter.

[0003] Sintering flue gas desulfurization (FGD) processes are classified into dry, semi-dry, and wet methods. Dry FGD has low efficiency, while wet FGD is corrosive and produces aerosols. Semi-dry FGD largely avoids the problems associated with both dry and wet methods, offering advantages such as meeting emission standards for the outlet flue gas and no corrosion to equipment and pipelines. Due to its advantages of low investment, small footprint, low water consumption, minimal equipment corrosion, dry byproducts, no wastewater generation, and simple process, semi-dry FGD has effectively overcome some of the problems and shortcomings of wet FGD, and has gradually become the dominant direction in FGD. However, with the promotion of semi-dry FGD, the desulfurization ash produced is difficult to utilize. The treatment of desulfurization ash from semi-dry FGD still mainly relies on stockpiling, which not only occupies land resources but also causes secondary pollution to the environment. Furthermore, the management and treatment costs increase the economic burden on enterprises. The comprehensive utilization of desulfurization ash has gradually become a major obstacle to the development of semi-dry FGD. The desulfurization ash from the semi-dry sintering flue gas desulfurization process is unstable and contains a large amount of calcium sulfite (CaSO3·0.5H2O). It is characterized by high calcium content, fine particle size, strong hydrophilicity, and poor stability. When the desulfurization ash is directly used in traditional sintering batching, it is difficult to granulate and mix it evenly during the sintering process. In addition, some of the desulfurization ash will be directly absorbed as dust during the sintering process, resulting in a lack of flux in the material layer, a reduction in the liquid phase, and poor strength of the sintered ore. Summary of the Invention

[0004] To address the problems in the background art regarding the difficulty in granulating and mixing desulfurization ash from the semi-dry sintering flue gas desulfurization process during sintering, and the resulting poor strength of the sintered ore, this invention provides a method for treating desulfurization ash from the semi-dry sintering flue gas desulfurization process.

[0005] The method of the present invention includes:

[0006] Step 1: Dry the desulfurization ash and then crush it with a crusher to obtain fine desulfurization ash powder;

[0007] Step 2: Pre-mix the desulfurization ash fine powder and dolomite powder in a mass ratio of (15-20):(80-85) and mix them thoroughly to obtain a homogeneous ash powder mixture;

[0008] Step 3: Use the ash powder homogenate as an ingredient in the preparation of the homogenized ore, wherein the ash powder homogenate accounts for 6.6-7.2% of the weight of the homogenized ore.

[0009] Step 4: Calculate the proportions of the mixed ore, return ore, fuel, and flux involved in the batching according to conventional sintering batching, and form the mixture;

[0010] Step 5: Feed the mixture into the sintering machine for feeding, ignition and sintering to obtain sintered ore.

[0011] Furthermore, in step two, the desulfurization ash fine powder and dolomite powder are fed into a high-powered mixer and mixed evenly.

[0012] Furthermore, in step three, the ash powder mixture is fed into the batching ore bin for building the blended ore pile, and mixed evenly to obtain the blended ore.

[0013] Furthermore, in step three, the homogenized ore comprises the following components in the following weight ratios: 5-10% carbide powder, 8-10% arsenic powder, 10-25% MAC powder, 10-25% king powder, 5-10% super-fine powder, 5-8% added powder, 8-15% mixed powder, 1-8% high-silica powder, 5-6% IOC6 powder, 5-8% Roy Mountain MB powder, 4-6% homogenized material, 0.1-0.3% iron dust and sludge, 1-2% undersize powder, and 6.6-7.2% ash powder homogenate.

[0014] Furthermore, in step four, the mixture consists of the following components in the following weight ratios: 58-65% blended ore, 25-30% recycled ore, 3.4-4% fuel, and 6.6-8% solvent.

[0015] Furthermore, the fuel is pulverized coal.

[0016] Furthermore, the solvent is limestone and granular ash, wherein the weight ratio of limestone is 3.6-4.5% and the weight ratio of granular ash is 3-3.5%.

[0017] Furthermore, in step four, the mixture is composed of the following components in the following weight ratios: 62.4% blended ore, 27% recycled ore, 3.4% coal powder, 4.0% limestone, and 3.2% granular ash. The mixture composed of these components exhibits minimal changes in all chemical compositions before and after sintering, resulting in a very stable sintering process.

[0018] Furthermore, in step four, the mixture is composed of the following components in the following weight ratios: 59% homogenizing powder, 26% recycled ore, 3.6% coal powder, 3.45% limestone, 4.4% dolomite, and 3.55% granular ash. The mixture composed of these components exhibits minimal changes in all chemical compositions before and after sintering, resulting in a very stable sintering process.

[0019] Furthermore, in the method described above, the weight ratio of the ash powder mixture to the homogenized ore is adjusted according to the SO2 emission concentration in the sintering machine.

[0020] Compared with existing technologies, this invention pre-mixes the desulfurization ash and dolomite powder in the semi-dry sintering flue gas desulfurization process, and then adds them to the mixed ore for secondary mixing. This makes the desulfurization ash more uniformly mixed during the sintering process, with the desulfurization ash and dolomite powder mutually coating each other. After sintering, the granulation is uniform, and the desulfurization ash is also prevented from being removed during subsequent sintering. This ensures that the amount of flux in the material layer, i.e., the amount of liquid phase, does not decrease, thus guaranteeing the strength of the sinter. This invention can consume the desulfurization ash from the semi-dry sintering flue gas desulfurization process. Utilizing its high calcium content, the desulfurization ash can act as a substitute flux, reducing flux consumption, stabilizing the sintering process, and obtaining qualified sinter with the required chemical composition after sintering. This meets the needs of blast furnace production, protects the environment, saves resources, and reduces the economic burden on enterprises. Attached Figure Description

[0021] Figure 1 This is a flowchart of the method of the present invention. Detailed Implementation

[0022] To make the technical problems, technical solutions, and beneficial effects to be solved by this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and are not intended to limit the scope of this application.

[0023] The process for treating desulfurization ash in a semi-dry sintering flue gas desulfurization process is illustrated in the flowchart below. Figure 1 As shown, the specific steps are as follows.

[0024] Step 1: Dry the desulfurization ash and then crush it with a crusher to obtain fine desulfurization ash powder.

[0025] The desulfurization ash from the semi-dry sintering flue gas desulfurization process has a high mass fraction of CaO, CaSO3, and CaSO4, which can replace part of the flux in sintering.

[0026] Step 2: Pre-mix the desulfurization ash fine powder and dolomite powder in a mass ratio of (15-20):(80-85) and mix them thoroughly to obtain a homogeneous ash powder mixture.

[0027] Specifically, the desulfurization ash fine powder and dolomite powder are fed into a high-powered mixer and mixed evenly.

[0028] Step 3: Use the ash powder homogenate as an ingredient in the preparation of the homogenized ore, wherein the ash powder homogenate accounts for 6.6-7.2% of the weight of the homogenized ore.

[0029] Specifically, the ash powder mixture is fed into the batching ore bin for building a homogenized ore pile, and mixed evenly to obtain homogenized ore.

[0030] More specifically, the blended ore comprises the following components in the following weight ratios: 5-10% carbide powder, 8-10% arsenic powder, 10-25% MAC powder, 10-25% king powder, 5-10% super-fine powder, 5-8% added powder, 8-15% mixed powder, 1-8% high silica powder, 5-6% IOC6 powder, 5-8% Roy Mountain MB powder, 4-6% homogenized material, 0.1-0.3% iron dust and sludge, 1-2% undersize powder, and 6.6-7.2% ash powder homogenate.

[0031] Step 4: Calculate the proportions of the mixed ore, return ore, fuel, and flux involved in the batching according to conventional sintering batching, and form a mixture.

[0032] Specifically, the mixture consists of the following components in the following weight ratios: 58-65% blended ore, 25-30% recycled ore, 3.4-4% fuel, and 6.6-8% solvent. The fuel is pulverized coal.

[0033] More specifically, the solvent is limestone and granular ash, wherein the weight ratio of limestone is 3.6-4.5% and the weight ratio of granular ash is 3-3.5%.

[0034] Preferably, the mixture consists of the following components in the following weight ratio: 62.4% blended ore, 27% recycled ore, 3.4% pulverized coal, 4.0% limestone, and 3.2% particulate ash. The mixture composed of these components exhibits minimal changes in all chemical compositions before and after sintering, resulting in a very stable sintering process.

[0035] Preferably, the mixture consists of the following components in the following weight ratios: 59% blending powder, 26% recycled ore, 3.6% coal powder, 3.45% limestone, 4.4% dolomite, and 3.55% granular ash. The mixture composed of these components exhibits minimal changes in all chemical compositions before and after sintering, resulting in a very stable sintering process.

[0036] In this method, the weight ratio of the ash powder mixture to the homogenized ore is adjusted according to the SO2 emission concentration in the sintering machine.

[0037] Example 1

[0038] The desulfurization ash is dried and then crushed by a crusher to obtain fine desulfurization ash powder.

[0039] The desulfurization ash fine powder and dolomite powder are pre-mixed at a mass ratio of 15:85 and fed into a high-power mixer to be fully mixed evenly to obtain a homogeneous ash powder mixture.

[0040] The ash powder homogenate is fed into the batching ore bin for building the homogenized ore pile, and mixed evenly to prepare homogenized ore. The composition of homogenized ore is as follows: 5% carbide powder, 9% arsenic powder, 13.8% MAC powder, 20% king powder, 10% super special powder, 7% added powder, 8.2% mixed powder, 1.2% high silica powder, 6% IOC6 powder, 7% Roy Mountain MB powder, 5.8% homogenized material, 0.3% iron dust sludge, and 6.7% ash powder homogenate.

[0041] The proportions of blended ore, recycled ore, fuel, and flux involved in the batching process are calculated according to conventional sintering batching methods, and the mixture is then formed. The composition of the mixture is as follows: blended ore 62.4%, recycled ore 27%, pulverized coal 3.4%, limestone 4.0%, and granular ash 3.2%.

[0042] The mixture is fed into a sintering machine for feeding, ignition, and sintering to obtain sintered ore.

[0043] Example 2

[0044] The desulfurization ash is dried and then crushed by a crusher to obtain fine desulfurization ash powder.

[0045] The desulfurization ash fine powder and dolomite powder are pre-mixed at a mass ratio of 15:85 and fed into a high-power mixer to be fully mixed evenly to obtain a homogeneous ash powder mixture.

[0046] The ash powder homogenate is fed into the batching ore bin for building the homogenized ore pile, and mixed evenly to prepare homogenized ore. The composition of homogenized ore is as follows: 7.7% carbide powder, 8% arsenic powder, 22% MAC powder, 16.1% king powder, 5.5% added powder, 14.1% mixed powder, 4.9% high silica powder, 4.2% IOC6 powder, 8% Roy Mountain MB powder, 0.4% iron dust sludge, 2% undersize powder, and 7.1% ash powder homogenate.

[0047] The proportions of blending ore, recycled ore, fuel, and flux involved in the batching are calculated according to conventional sintering batching methods, and the mixture is formed as follows: blending powder 59%, recycled ore 26%, coal powder 3.6%, limestone 3.45%, dolomite 4.4%, and granular ash 3.55%.

[0048] The mixture is fed into a sintering machine for feeding, ignition, and sintering to obtain sintered ore.

[0049] Example 3

[0050] The desulfurization ash is dried and then crushed by a crusher to obtain fine desulfurization ash powder.

[0051] The desulfurization ash fine powder and dolomite powder are pre-mixed in a mass ratio of 18:82 and fed into a high-power mixer to be fully mixed evenly to obtain a homogeneous ash powder mixture.

[0052] The ash powder homogenate is fed into the batching trough of the homogenized ore pile and mixed evenly to prepare homogenized ore. The composition of homogenized ore is as follows: 6% carbide powder, 8% arsenic powder, 20% MAC powder, 12% king powder, 8% super-special powder, 6% added powder, 9% mixed powder, 5% high silica powder, 5.5% IOC6 powder, 6% Roy Mountain MB powder, 5.5% homogenized material, 0.2% iron dust and sludge, 2% undersize powder, and 6.8% ash powder homogenate.

[0053] The proportions of blended ore, recycled ore, fuel, and flux involved in the batching are calculated according to conventional sintering batching methods, and the mixture is formed as follows: blended ore 62%, recycled ore 26%, pulverized coal 4%, limestone 4.5%, and granular ash 3.5%.

[0054] The mixture is fed into a sintering machine for feeding, ignition, and sintering to obtain sintered ore.

[0055] Example 4

[0056] The desulfurization ash is dried and then crushed by a crusher to obtain fine desulfurization ash powder.

[0057] The desulfurization ash fine powder and dolomite powder are pre-mixed in a mass ratio of 16:84 and fed into a high-power mixer to be fully mixed evenly to obtain a homogeneous ash powder mixture.

[0058] The ash powder homogenate is fed into the batching trough of the homogenized ore pile and mixed evenly to prepare homogenized ore. The composition of homogenized ore is as follows: 8% carbide powder, 8% arsenic powder, 18% MAC powder, 10% king powder, 10% super special powder, 6% added powder, 10% mixed powder, 4% high silica powder, 5.5% IOC6 powder, 6% Roy Mountain MB powder, 5.5% homogenized material, 0.3% iron dust and sludge, 1.5% undersize powder, and 7.2% ash powder homogenate.

[0059] The proportions of blended ore, recycled ore, fuel, and flux involved in the batching are calculated according to conventional sintering batching methods, and the mixture is formed as follows: blended ore 58%, recycled ore 30%, pulverized coal 4%, limestone 4.5%, and granular ash 3.5%.

[0060] The mixture is fed into a sintering machine for feeding, ignition, and sintering to obtain sintered ore.

[0061] Example 5

[0062] The desulfurization ash is dried and then crushed by a crusher to obtain fine desulfurization ash powder.

[0063] The desulfurization ash fine powder and dolomite powder are pre-mixed at a mass ratio of 20:80 and fed into a high-power mixer to be fully mixed evenly to obtain a homogeneous ash powder mixture.

[0064] The ash powder homogenate is fed into the batching ore bin for building the homogenized ore pile, and mixed evenly to prepare homogenized ore. The composition of homogenized ore is as follows: 10% carbide powder, 10% arsenic powder, 20% MAC powder, 10% king powder, 10% super special powder, 6% added powder, 10.2% mixed powder, 4.1% high silica powder, 5% IOC6 powder, 6% Roy Mountain MB powder, 0.1% iron dust sludge, 2% undersize powder, and 6.6% ash powder homogenate.

[0065] The proportions of blended ore, recycled ore, fuel, and flux involved in the batching are calculated according to conventional sintering batching methods, and the mixture is formed as follows: blended ore 65%, recycled ore 25%, pulverized coal 3.4%, limestone 3.6%, and granular ash 3%.

[0066] The mixture is fed into a sintering machine for feeding, ignition, and sintering to obtain sintered ore.

[0067] The components of the mixed ore and sintered ore in Examples 1-5 were tested respectively, and the results are shown in Table 1. It can be seen that the chemical composition of the sintered ore obtained after sintering in this invention meets the requirements, and the components meet the needs of blast furnace production.

[0068] Table 1. Summary of the composition of blended ore and sintered ore

[0069]

[0070]

[0071] This invention, by employing the aforementioned technical solution, solves the problems of fine particle size, strong hydrophilicity, unstable properties, difficulty in granulation using traditional batching methods, and the direct absorption of some desulfurization ash as dust during exhaust sintering in the sintering machine, resulting in insufficient flux, insufficient CaO, reduced liquid phase, and decreased strength of the sintered ore. This invention mixes desulfurization ash with dolomite powder, and the mixed ore is further mixed during the build-up process. This ensures thorough mixing and coating of dolomite powder, desulfurization ash, and other components, effectively preventing the desulfurization ash from being absorbed during sintering, consuming the ash, utilizing its fluxing effect, and stabilizing the sintering process. Furthermore, the proportion of desulfurization ash added during the process can be adjusted according to the SO2 emission concentration of the sintering machine.

[0072] In particular, the mixtures of Examples 1 and 2 showed little change in all chemical components before and after sintering, and the sintering process was very stable.

[0073] The above-described embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application, and should all be included within the protection scope of this application.

Claims

1. A method for treating desulfurization ash from a semi-dry sintering flue gas desulfurization process, characterized in that, include: Step 1: Dry the desulfurization ash and then crush it with a crusher to obtain fine desulfurization ash powder; Step 2: Pre-mix the desulfurization ash fine powder and dolomite powder in a mass ratio of (15-20):(80-85) and mix them thoroughly to obtain a homogeneous ash powder mixture; Step 3: Use the ash powder homogenate as an ingredient in the preparation of the homogenized ore, wherein the ash powder homogenate accounts for 6.6-7.2% of the weight of the homogenized ore; Step 4: Calculate the proportions of the blending ore, return ore, fuel, and flux involved in the batching process according to conventional sintering batching methods, and form a mixture. The mixture consists of the following components in the following weight ratios: blending ore 58-65%, return ore 25-30%, fuel 3.4-4%, and flux 6.6-8%. The flux is limestone and granular ash, wherein the weight ratio of limestone is 3.6-4.5% and the weight ratio of granular ash is 3-3.5%. The fuel is pulverized coal. Step 5: Feed the mixture into the sintering machine for feeding, ignition and sintering to obtain sintered ore; In the method, the weight ratio of the ash powder mixture to the mixed ore is adjusted according to the SO2 emission concentration in the sintering machine.

2. The method for treating desulfurization ash in the semi-dry sintering flue gas desulfurization process according to claim 1, characterized in that: In step two, the desulfurization ash fine powder and dolomite powder are fed into a high-powered mixer and mixed evenly.

3. The method for treating desulfurization ash in the semi-dry sintering flue gas desulfurization process according to claim 2, characterized in that: In step three, the ash powder mixture is fed into the batching ore bin for building the blended ore pile, and mixed evenly to obtain the blended ore.

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