Utilization method of coal derived dust

Abstract

The invention discloses a utilization method of coal-derived dust, belongs to the technical field of solid waste utilization, and aims to solve the problems of environmental pollution and germanium resource waste in coal-derived dust easily caused by solid waste stacking of coal-derived dust in the prior art. The utilization method comprises the following steps: collecting coal derived dust; the coal-derived dust is subjected to a primary fluidization reduction reaction, coal-derived dust subjected to primary fluidization reduction and flue gas subjected to primary fluidization reduction are obtained, and the flue gas subjected to primary fluidization reduction contains germanium monoxide; the coal derived dust subjected to primary fluidization reduction is subjected to a secondary fluidization reduction reaction, tailings obtained after the secondary fluidization reduction reaction and flue gas obtained after the secondary fluidization reduction reaction are obtained, and the flue gas obtained after the secondary fluidization reduction reaction contains germanium monoxide; and collecting the flue gas after the primary fluidization reduction reaction and the flue gas after the secondary fluidization reduction reaction to realize enrichment of germanium in the coal-derived dust and complete utilization of the coal-derived dust. The method can be used for utilizing the coal derived dust.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of solid waste utilization, and particularly relates to a utilization method of coal-derived dust. BACKGROUND

[0002] In industrial production, germanium-containing coal is often used in the fields of power generation, heating and the like, and in particular in low-temperature combustion processes (usually referring to combustion processes with a combustion temperature lower than 1000 DEG C), the organic components and part of the inorganic components in the germanium-containing coal will undergo combustion reaction, generating heat energy and also a large amount of fly ash solid waste. Since germanium is not easy to volatilize in the combustion process and is mostly enriched in the form of oxides and the like in the fly ash, the fly ash becomes a typical coal-derived dust solid waste.

[0003] At present, the treatment method for the coal-derived dust solid waste is mainly stacking and storage, and this treatment method has two major problems: on the one hand, the coal-derived dust solid waste has fine particles and light quality, and is easy to produce dust under the action of wind, polluting the surrounding atmospheric environment; on the other hand, the content of germanium in the coal-derived dust solid waste is usually between 50-500 g / t, and the content of germanium in part of the high-quality coal-derived dust solid waste even exceeds 1000 g / t, having a very high extraction value. If it is directly discarded and stacked, a large amount of valuable germanium resources will be wasted. SUMMARY

[0004] In view of the above analysis, the present application aims to provide a utilization method of coal-derived dust, so as to solve the problems of environmental pollution caused by stacking of the coal-derived dust solid waste and waste of germanium resources in the coal-derived dust in the prior art.

[0005] The present application provides a utilization method of coal-derived dust, comprising the following steps:

[0006] Step 1: collecting coal-derived dust;

[0007] Step 2: performing a first fluidized reduction reaction on the coal-derived dust to obtain first fluidized reduction after coal-derived dust and first fluidized reduction after flue gas, the first fluidized reduction after flue gas containing germanium monoxide;

[0008] Step 3: performing a second fluidized reduction reaction on the first fluidized reduction after coal-derived dust to obtain second fluidized reduction reaction after tailings and second fluidized reduction reaction after flue gas, the second fluidized reduction reaction after flue gas containing germanium monoxide;

[0009] Step 4: collecting the first fluidized reduction after flue gas and the second fluidized reduction reaction after flue gas to realize enrichment of germanium in the coal-derived dust and complete utilization of the coal-derived dust.

[0010] Further, in step 2, the temperature of the first fluidized reduction reaction is 800-950℃, and the time of the first fluidized reduction reaction is 30-40 minutes.

[0011] Further, in step 2, the following step is further included before the first fluidized reduction reaction:

[0012] The coal-derived dust is preheated to a temperature of 800-950℃.

[0013] Further, in step 3, the temperature of the second fluidized reduction reaction is 1100-1350℃, and the time of the second fluidized reduction reaction is 30-60 minutes.

[0014] Further, in step 3, the following step is further included before the second fluidized reduction reaction:

[0015] The coal-derived dust after the first fluidized reduction reaction is preheated to a temperature of 1100-1350℃.

[0016] Further, in steps 2 and 3, the molar ratio of germanium dioxide to reducing gas is 1:1.05-1.10.

[0017] Further, the following step is further included between step 1 and step 2:

[0018] The coal-derived dust is subjected to a fluidized oxidation reaction, so that germanium monosulfide, germanium disulfide and germanium sulfide in the coal-derived dust are converted into germanium dioxide.

[0019] Further, the temperature of the fluidized oxidation reaction is 600-800℃, and the time of the fluidized oxidation reaction is 30-50 minutes.

[0020] Further, the following step is further included between step 1 and step 2:

[0021] The coal-derived dust is dry ground, so that the mass percentage of particles with a particle size of less than 0.045 mm in the total coal-derived dust is more than 75%.

[0022] Further, the following step is further included after step 4:

[0023] The flue gas after the first fluidized reduction reaction and the flue gas after the second fluidized reduction reaction are subjected to cyclone separation by using a cyclone separator, to obtain cyclone separation solid phase and cyclone separation flue gas;

[0024] The cyclone separation flue gas is subjected to dust removal by using a bag-type dust collector, and the dust in the bag-type dust collector is collected, and the cyclone separation solid phase and the dust in the bag-type dust collector are germanium monosulfide.

[0025] Compared with the prior art, the present application can achieve at least one of the following beneficial effects:

[0026] A) The coal-derived dust utilization method provided by the present application can reduce germanium dioxide and silicon-germanium solid solution in the coal-derived dust to germanium monoxide through two fluidization reduction reactions, and germanium can be enriched and the coal-derived dust solid waste can be effectively utilized by collecting flue gas containing germanium monoxide due to the volatility of germanium monoxide.

[0027] B) The coal-derived dust utilization method provided by the present application can effectively improve the catalytic reaction efficiency and shorten the catalytic reaction time by keeping the coal-derived dust in a fluidized state during the first reduction and the second fluidization reduction reaction, so that the coal-derived dust can fully contact with the reducing gas to occur reduction reaction.

[0028] The above technical solutions can be combined with each other in the present application to achieve more preferred combination solutions. Other features and advantages of the present application will be described in the subsequent specification, and some advantages will become apparent from the specification, or will be understood by implementing the present application. The purpose and other advantages of the present application can be achieved and obtained from the contents specifically pointed out in the specification and the drawings. BRIEF DESCRIPTION OF DRAWINGS

[0029] The accompanying drawings are included to provide a further understanding of the present application and are incorporated in and constitute a part of this specification, illustrate embodiments of the present application and serve to explain the principles of the present application, and are not intended to limit the scope of the present application.

[0030] Figure 1 A flowchart of the coal-derived dust utilization method provided by the present application. DETAILED DESCRIPTION

[0031] The preferred embodiments of the present application will be specifically described below in conjunction with the drawings, wherein the drawings constitute a part of the present application and are used to illustrate the principles of the embodiments of the present application, and are not intended to limit the scope of the present application.

[0032] The present application provides a coal-derived dust utilization method, referring to Figure 1 , comprising the following steps:

[0033] Step 1: Collecting coal-derived dust, the coal-derived dust includes germanium-containing flue dust and / or germanium-containing fly ash, wherein the germanium-containing flue dust contains germanium monoxide, germanium monosulfide and germanium disulfide, and the germanium-containing fly ash contains germanium dioxide and silicon-germanium solid solution (for example, germanium silicate);

[0034] Step 2: a first fluidized reduction reaction is performed on the coal-derived dust, so that germanium dioxide in the coal-derived dust is reduced to germanium monoxide, and the germanium monoxide is volatilized, to obtain first fluidized reduction after coal-derived dust and first fluidized reduction after flue gas, the first fluidized reduction after flue gas containing germanium monoxide;

[0035] Step 3: a second fluidized reduction reaction is performed on the first fluidized reduction after coal-derived dust, so that the silicon germanium solid solution in the first fluidized reduction after coal-derived dust is reduced to germanium monoxide, and the germanium monoxide is volatilized, to obtain second fluidized reduction after tailings and second fluidized reduction after flue gas, the second fluidized reduction after flue gas containing germanium monoxide;

[0036] Step 4: the first fluidized reduction after flue gas and the second fluidized reduction after flue gas are collected, to realize the enrichment of germanium in the coal-derived dust, and complete the utilization of the coal-derived dust.

[0037] Specifically, the reaction formula of the first fluidized reduction reaction is as follows:

[0038] GeO2(s)+CO(g)=GeO(g)+CO2(g)

[0039] The reaction formula of the second fluidized reduction reaction is as follows:

[0040] GeO2-SiO2(silicon germanium solid solution)+CO(g)→GeO(g)+CO2(g)+SiO2(s)

[0041] Compared with the prior art, the utilization method of the coal-derived dust provided by the present application can reduce germanium dioxide and silicon germanium solid solution in the coal-derived dust to germanium monoxide through two fluidized reduction reactions (first low-temperature reduction and second high-temperature reduction), and can realize the enrichment of germanium and the effective utilization of the coal-derived dust solid waste by collecting flue gas containing germanium monoxide due to the volatility of germanium monoxide.

[0042] On the other hand, the coal-derived dust is always in a fluidized state during the sequential reduction and second fluidized reduction reaction, and the coal-derived dust can fully contact with the reducing gas to occur a reduction reaction, thereby effectively improving the catalytic reaction efficiency and shortening the catalytic reaction time.

[0043] In order to realize the first fluidized reduction reaction, for example, in the above step 2, the first fluidized reduction reaction temperature is 800℃-950℃, and the first fluidized reduction reaction time is 30min-40min.

[0044] In view of the fact that the coal-derived dust is in a fluidized state and flows at a high speed during the primary fluidized reduction reaction, in order to quickly perform the primary fluidized reduction reaction, the step 2 further includes the following step before the primary fluidized reduction reaction:

[0045] The coal-derived dust is preheated to a temperature of 800-950°C.

[0046] Correspondingly, in order to perform the secondary fluidized reduction reaction, the temperature of the secondary fluidized reduction reaction is 1100-1350°C and the time of the secondary fluidized reduction reaction is 30-60 minutes in the step 3.

[0047] In view of the fact that the coal-derived dust is in a fluidized state and flows at a high speed after the primary fluidized reduction reaction, in order to quickly perform the secondary fluidized reduction reaction, the step 3 further includes the following step before the secondary fluidized reduction reaction:

[0048] The coal-derived dust after the primary fluidized reduction reaction is preheated to a temperature of 1100-1350°C.

[0049] It should be noted that the amount of reducing gas required for the primary fluidized reduction reaction and the secondary fluidized reduction reaction is determined according to the germanium content. For example, the molar ratio of germanium dioxide to reducing gas is 1:1.05-1.10. When the flow rate of the reducing gas is insufficient to ensure that the coal-derived dust is always in a fluidized state, an inert gas is used to make up for it.

[0050] In order to fully utilize germanium monosulfide and germanium disulfide in the germanium-containing flue dust, the step 1 and the step 2 further include the following step:

[0051] The coal-derived dust is subjected to a fluidized oxidation reaction, so that germanium monoxide, germanium disulfide and germanium sulfide in the coal-derived dust are converted into germanium dioxide, the germanium monoxide, the germanium disulfide and the germanium sulfide are fixed, volatile impurities such as sulfur and arsenic are removed, and the complex mineral structure is destroyed.

[0052] Specifically, the reaction formula of the fluidized oxidation reaction is as follows:

[0053] 2GeO + O2→ 2GeO2;

[0054] GeS2+ 3O2→ GeO2+ 2SO2;

[0055] GeS + 2O2→ GeO2+ SO2.

[0056] In order to promote the full flow of the fluidized oxidation reaction, the temperature of the fluidized oxidation reaction is 600-800 DEG C, and the fluidized oxidation reaction time is 30-50 min.

[0057] In order to break the germanium-silicon solid solution to germanium, and improve the utilization rate of coal-derived dust, the steps 1 and 2 further comprise the following steps:

[0058] The coal-derived dust is dry ground, so that the mass percentage of the coal-derived dust particles with a particle size of less than 0.045 mm in the total coal-derived dust is more than 75%.

[0059] In order to further collect germanium oxide, the step 4 further comprises the following steps:

[0060] The cyclone separator is used to separate the flue gas after the first fluidized reduction and the flue gas after the second fluidized reduction reaction, to obtain a cyclone separation solid phase and a cyclone separation flue gas;

[0061] The bag filter is used to remove dust from the cyclone separation flue gas, and the dust in the bag filter is collected, and the cyclone separation solid phase and the dust in the bag filter are germanium monoxide.

[0062] In the second aspect, the present application provides a method for utilizing coal-derived dust, which has the same steps as the method for utilizing coal-derived dust provided in the first aspect, and the difference is that:

[0063] It is worth noting that the fluidized oxidation reaction temperature ranges of germanium monoxide, germanium disulfide and germanium monosulfide are different, the fluidized oxidation reaction temperature of germanium monoxide (250-300 DEG C) < the fluidized oxidation reaction temperature of germanium monosulfide (400-500 DEG C) < the fluidized oxidation reaction temperature of germanium disulfide (600-700 DEG C), if the three are subjected to fluidized oxidation reaction in the same chamber, in order to ensure the reaction completeness of the three, the fluidized oxidation reaction temperature needs to be controlled to be greater than the oxidation reaction temperature of germanium disulfide, however, this not only causes the germanium monoxide and germanium monosulfide to undergo severe oxidation reaction, but also causes the energy consumption to increase.

[0064] Therefore, based on the different densities of germanium monoxide, germanium disulfide and germanium monosulfide (the density of germanium disulfide < the density of germanium monoxide, the density of germanium monosulfide), the fluidized oxidation reaction of the coal-derived dust is carried out in a fluidized oxidation tank, the bottom of the fluidized oxidation tank is provided with an inert gas inlet and a coal-derived dust inlet, the inert gas inlet is connected with an inert gas supply unit, the middle of the fluidized oxidation tank is provided with an oxidizing gas inlet, the oxidizing gas inlet is connected with an oxidizing gas supply unit, and the middle and upper part of the fluidized oxidation tank is provided with a heating assembly.

[0065] Exemplarily, the fluidized oxidation reaction of the coal-derived dust includes the following steps:

[0066] Step a: turn on the inert gas supply unit, the oxidizing gas supply unit and the heating assembly, the total supply flow rate of the inert gas and the oxidizing gas is in a first flow rate range, the oxidation reaction temperature is in a first temperature range (600-800℃), the germanium disulfide in the coal-derived dust is in a fluidized state, the fluidized oxidation reaction is carried out in the middle and upper parts of the fluidized oxidation tank, the germanium monosulfide and the germanium monoxide are in the lower part of the fluidized oxidation tank and are not in a fluidized state, so the fluidized oxidation reaction does not occur to the germanium monosulfide and the germanium monoxide;

[0067] Step b: turn off the heating assembly and increase the supply flow rate of the inert gas, so that the total supply flow rate of the inert gas and the oxidizing gas is in a second flow rate range, the total supply flow rate of the inert gas and the oxidizing gas in the second flow rate range is greater than that in the first flow rate range, the germanium monosulfide and the germanium monoxide in the lower part of the fluidized oxidation tank are fluidized under the action of the inert gas and are blown to the middle and upper parts of the fluidized oxidation tank, and the fluidized oxidation reaction is carried out by using the residual heat of the fluidized oxidation tank.

[0068] In this way, the density difference between the germanium disulfide, the germanium monosulfide and the germanium monoxide and the supply flow rate of the inert gas are utilized to separate the germanium disulfide, the germanium monosulfide and the germanium monoxide, so that the germanium disulfide is subjected to the fluidized oxidation reaction in the middle and upper parts of the fluidized oxidation tank, the gap density between the particles is large, so the germanium disulfide can fully react with the oxidizing gas and the fluidized oxidation reaction is fast and complete, when the germanium disulfide is completely reacted, the supply flow rate of the inert gas is increased, so that the germanium monosulfide and the germanium monoxide are in a fluidized state and are subjected to the fluidized oxidation reaction, at this time, the residual heat in the fluidized oxidation tank can make the germanium monosulfide and the germanium monoxide be subjected to the fluidized oxidation reaction without turning on the heating assembly, which not only can effectively reduce the energy consumption, but also can avoid the violent fluidized oxidation reaction of the germanium monosulfide and the germanium monoxide at high temperature, thereby ensuring the safety of the whole device.

[0069] Embodiment one

[0070] In this embodiment, the germanium in the coal-derived dust is extracted by using the method for utilizing the coal-derived dust, the raw material is high-sulfur germanium-containing smoke dust, and the composition includes Ge 1.03%, Si 6.23%, S 4.35%, Al 0.23%, Fe 2.36%, Ca 1.63%, Zn 40.01%, Pb 15.63% and other elements according to the mass percentage.

[0071] The specific extraction process includes the following steps:

[0072] Step A: collect the germanium-containing smoke dust just after combustion;

[0073] Step B: Dry grinding the germanium-containing fumes, and the ground product is required to have a particle size of less than 0.045 mm, and the mass content of the particles is more than 75%;

[0074] Step C: Preheating the dry-ground germanium-containing fumes to a temperature of 700°C, and then performing a fluidized oxidation reaction at a temperature of 700°C for 30 min;

[0075] Step D: Preheating the oxidized germanium-containing fumes to a temperature of 900°C, and then performing a first fluidized reduction reaction at a temperature of 900°C for 30 min, with a molar ratio of GeO2 to reducing gas being 1:1.05;

[0076] Step E: Preheating the germanium-containing fumes after the first fluidized reduction reaction to a temperature of 1100°C, and then performing a second fluidized reduction reaction at a temperature of 1100°C for 50 min, with a molar ratio of GeO2 to reducing gas being 1:1.05;

[0077] Step F: Collecting the germanium monoxide after gasification, and calculating that the germanium volatilization rate is more than 99.6%.

[0078] Example Two

[0079] In this example, germanium in coal-derived dust is extracted by using the method for utilizing coal-derived dust. The raw material is germanium-containing coal fly ash, which includes Ge 0.33%, C 4.36%, Fe 13.66%, Si 17.89%, Al 5.78%, Ca 10.23%, K 1.25%, Na 0.96%, Mg 2.58%, and other elements, in terms of mass percentage.

[0080] The specific extraction process includes the following steps:

[0081] Step A: Collecting germanium-containing coal fly ash just after combustion;

[0082] Step B: Dry grinding the germanium-containing coal fly ash, and the ground product is required to have a particle size of less than 0.045 mm, and the mass content of the particles is more than 75%;

[0083] Step C: Preheating the dry-ground germanium-containing coal fly ash to a temperature of 800°C, and then performing a first fluidized reduction reaction at a temperature of 800°C for 40 min, with a molar ratio of GeO2 to reducing gas being 1:1.10;

[0084] Step D: The germanium-containing fly ash after the first fluidized reduction reaction was preheated to a temperature of 1300°C, and then a second fluidized reduction reaction was performed at a temperature of 1300°C, and the reaction time was 55 min, and the molar ratio of GeO2 to reducing gas was 1:1.10.

[0085] Step E: The germanium vaporization rate was calculated to be more than 99.4% after the germanium monoxide was collected.

[0086] Example Three

[0087] In this example, germanium was extracted from coal-derived dust by using a coal-derived dust utilization method. The raw materials were high-sulfur germanium-containing flue dust and germanium-containing fly ash. The composition of the high-sulfur germanium-containing flue dust included, by mass percentage, Ge 1.03%, Si 6.23%, S 4.35%, Al 0.23%, Fe 2.36%, Ca 1.63%, Zn 40.01%, Pb 15.63%, and other elements. The composition of the germanium-containing fly ash included, by mass percentage, Ge 0.33%, C 4.36%, Fe 13.66%, Si 17.89%, Al 5.78%, Ca 10.23%, K 1.25%, Na 0.96%, Mg 2.58%, and other elements.

[0088] The specific extraction process included the following steps:

[0089] Step A: Collecting the coal-derived dust and germanium-containing fly ash immediately after combustion;

[0090] Step B: Dry grinding the coal-derived dust, and the ground product required that the mass content of particles with a particle size of less than 0.045 mm was more than 75%;

[0091] Step C: Preheating the dry-ground coal-derived dust to a temperature of 700°C, and then performing a fluidized oxidation reaction at a temperature of 800°C, and the reaction time was 45 min;

[0092] Step D: Preheating the oxidized coal-derived dust to a temperature of 950°C, and then performing a first fluidized reduction reaction at a temperature of 950°C, and the reaction time was 40 min, and the molar ratio of GeO2 to reducing gas was 1:1.05;

[0093] Step E: Preheating the coal-derived dust after the first fluidized reduction reaction to a temperature of 1200°C, and then performing a second fluidized reduction reaction at a temperature of 1100°C, and the reaction time was 60 min, and the molar ratio of GeO2 to reducing gas was 1:1.05;

[0094] Step F: The germanium monoxide after gasification was collected, and the germanium volatilization rate was calculated to be more than 99.5%.

[0095] The above description is merely preferred embodiments of the present application, but the protection scope of the present application is not limited thereto, and any person skilled in the art can easily think of changes or replacements within the technical scope disclosed by the present application, which should be covered within the protection scope of the present application.

Claims

1. A method of utilizing coal-derived dust, characterized by, The method comprises the following steps: Step 1: collecting coal-derived dust; Step 2: performing a first fluidized reduction reaction on the coal-derived dust to obtain first fluidized reduction reaction coal-derived dust and first fluidized reduction reaction flue gas, wherein the first fluidized reduction reaction flue gas contains germanium monoxide; Step 3: performing a second fluidized reduction reaction on the first fluidized reduction reaction coal-derived dust to obtain second fluidized reduction reaction tailings and second fluidized reduction reaction flue gas, wherein the second fluidized reduction reaction flue gas contains germanium monoxide; Step 4: collecting the first fluidized reduction reaction flue gas and the second fluidized reduction reaction flue gas to enrich germanium in the coal-derived dust and complete the utilization of the coal-derived dust.

2. The method of utilizing coal-derived dust according to claim 1, characterized by, In the step 2, the first fluidized reduction reaction temperature is 800-950 DEG C, and the first fluidized reduction reaction time is 30-40 min.

3. The method of utilizing coal-derived dust according to claim 2, characterized by, In the step 2, the following step is further included before the first fluidized reduction reaction: preheating the coal-derived dust to raise the temperature of the coal-derived dust to 800-950 DEG C.

4. The method of utilizing coal-derived dust according to claim 1, characterized by, In the step 3, the second fluidized reduction reaction temperature is 1100-1350 DEG C, and the second fluidized reduction reaction time is 30-60 min.

5. The method of utilizing coal-derived dust according to claim 4, characterized by, In the step 3, the following step is further included before the second fluidized reduction reaction: preheating the first fluidized reduction reaction coal-derived dust to raise the temperature of the first fluidized reduction reaction coal-derived dust to 1100-1350 DEG C.

6. The method of utilizing coal-derived dust according to claim 1, characterized by, In the steps 2 and 3, the molar ratio of germanium dioxide to reducing gas is 1:1.05-1.

10.

7. The method of utilizing coal-derived dust according to any one of claims 1 to 6, characterized by, The following step is further included between the steps 1 and 2: performing a fluidized oxidation reaction on the coal-derived dust to convert germanium monoxide, germanium disulfide and germanium sulfide in the coal-derived dust into germanium dioxide.

8. The method of utilizing coal-derived dust according to claim 7, characterized by, The fluidized oxidation reaction temperature is 600-800 DEG C, and the fluidized oxidation reaction time is 30-50 min.

9. The method of utilizing coal-derived dust according to any one of claims 1 to 6, characterized by, The following step is further included between the steps 1 and 2: dry grinding the coal-derived dust to make the mass percentage of particles with a particle size less than 0.045 mm in the total coal-derived dust be more than 75%.

10. The method of utilizing coal-derived dust according to any one of claims 1 to 6, characterized by, The following step is further included after the step 4: performing cyclone separation on the first fluidized reduction reaction flue gas and the second fluidized reduction reaction flue gas by using a cyclone separator to obtain cyclone separation solid phase and cyclone separation flue gas; performing dust removal on the cyclone separation flue gas by using a bag-type dust collector, collecting dust in the bag-type dust collector, and the cyclone separation solid phase and the dust in the bag-type dust collector being germanium monoxide.

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