Resource utilization method for red mud storage yard backwater cooperating with coal gas
By chemically reacting the return water of the red mud yard with coal-to-gas, and purifying and utilizing sodium sulfide, the consumption and environmental pressure of the coal-to-gas desulfurization process in the existing technology, as well as the environmental pressure of the return water of the red mud yard, achieving efficient recycling of resources and improving product quality.
Patent Information
- Application Number
- CN202411785818.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-06
- Publication Date
- 2025-03-07
AI Technical Summary
The existing coal-to-gas moisture oxidation and desulfurization process has consumption and environmental pressure, and the return water of the red mud yard also brings environmental pressure.
By chemically reacting the return water of the red mud yard with coal-to-gas, the return water containing sodium sulfide and the purified coal-to-gas are generated. Then, the sodium sulfide is mixed with the sodium aluminate solution for purification to obtain a pure sodium aluminate solution, and the treated return water and coal-to-gas are returned to the corresponding process for recycling.
The resource utilization of return water and coal-to-gas in the red mud yard has been realized, the process cost and environmental pressure have been reduced, and the recycling rate of resources and product quality have been improved.
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Figure CN119569094A_ABST
Abstract
Description
Technical Field
[0001] The present application relates to the technical field of environmental protection and comprehensive resource utilization, and in particular to a method for resource utilization of red mud dump return water in coordination with coal-to-gas. Background Art
[0002] Coal gas desulfurization methods include wet processes. The wet process uses liquid desulfurizers to remove H2S from coal gas. It is divided into absorption and oxidation methods. In the existing coal gas wet oxidation desulfurization, the oxidants are purchased outside the process, and there is consumption in the process of recovering H2S. In addition, most of the existing desulfurization processes convert hydrogen sulfide into sulfur paste (elemental sulfur), which has a high impurity content and low purity, bringing great environmental pressure to subsequent storage and reprocessing.
[0003] Red mud dump backwater refers to the red mud that has been washed in reverse for many times and then filtered by a filter press to meet the external discharge standards and then discharged and piled up. The moisture content of the filter cake after the red mud is filtered is between 20% and 40%. The alkaline backwater recovered from the red mud dump is called dump backwater. Red mud dump backwater also has great environmental pressure. Summary of the invention
[0004] The present application provides a method for resource utilization of red mud dump return water in coordination with coal gasification to solve the following technical problem: providing a method for resource utilization of red mud dump return water in coordination with coal gasification.
[0005] In a first aspect, an embodiment of the present application provides a method for resource utilization of red mud dump return water in coordination with coal gasification, the method comprising:
[0006] Chemically reacting the first red mud dump return water with the first coal-based gas to obtain the second red mud dump return water containing sodium sulfide and the second coal-based gas;
[0007] crystallize the second red mud dump return water containing sodium sulfide to obtain sodium sulfide and the third red mud dump return water;
[0008] Mixing sodium sulfide with a sodium aluminate solution so that the sodium sulfide is used as a purifier of the sodium aluminate solution for recycling to obtain a pure sodium aluminate solution;
[0009] Returning the return water from the third red mud dump to the alumina production process to serve as washing liquid for the red mud in the alumina production process for recycling; and
[0010] The second coal-generated gas is returned to the alumina production process to be used as roasting fuel for the alumina production process for recycling.
[0011] Optionally, the flow rate of the red mud dump return water is 10L / h to 35L / h.
[0012] Optionally, the flow rate of the red mud dump return water is 20L / h to 29L / h.
[0013] Optionally, the flow rate of the first coal-to-gas is 0.8m 3 / h~1.5m 3 / h.
[0014] Optionally, the flow rate of the first coal-to-gas is 1m 3 / h.
[0015] Optionally, the chemical reaction of the first red mud dump return water with the first coal-based gas to obtain the second red mud dump return water containing sodium sulfide and the second coal-based gas comprises:
[0016] The first red mud dump return water and the first coal gasification are chemically reacted to obtain the second red mud dump return water containing sodium sulfide and the second coal gasification; wherein the first red mud dump return water is introduced from the top of the reaction device from top to bottom, and the first coal gasification is introduced from the bottom to top of the reaction device, and the reaction device has a set height-to-diameter ratio.
[0017] Optionally, the aspect ratio is set to be 4 to 4.5.
[0018] Optionally, the return water to the first red mud dump is introduced by spraying.
[0019] Optionally, the sodium sulfide is mixed with the sodium aluminate solution so that the sodium sulfide is used as a purifier of the sodium aluminate solution for recycling to obtain a pure sodium aluminate solution, comprising:
[0020] Mixing sodium sulfide with a sodium aluminate solution so that the sodium sulfide is used as a purifier of the sodium aluminate solution for recycling to obtain a pure sodium aluminate solution;
[0021] The pure sodium aluminate solution is decomposed to obtain aluminum hydroxide; wherein the whiteness of the aluminum hydroxide is greater than 95%.
[0022] Optionally, the H2S content in the first coal-to-gas is 1830 mg / m 3 ~2260 mg / m 3 The H2S content in the second coal-to-gas is <5 mg / m 3 .
[0023] The above technical solution provided by the embodiment of the present application has the following advantages compared with the prior art:
[0024] The embodiment of the present application provides a method for resource utilization of red mud dump return water in coordination with coal gasification, the method comprising: chemically reacting the first red mud dump return water with the first coal gasification to obtain the second red mud dump return water and the second coal gasification containing sodium sulfide; crystallizing the second red mud dump return water containing sodium sulfide to obtain sodium sulfide and the third red mud dump return water; mixing the sodium sulfide with a sodium aluminate solution so that the sodium sulfide is used as a purifier of the sodium aluminate solution for recycling to obtain a pure sodium aluminate solution; returning the second red mud dump return water to the alumina production process to serve as a washing liquid for the red mud of the alumina production process for recycling; and returning the second coal gasification to the alumina production process to serve as a roasting fuel for the alumina production process for recycling. The sodium hydroxide in the first red mud dump return water reacts chemically with the hydrogen sulfide and carbonyl sulfide in the first coal gasification to generate sodium sulfide, thereby reducing the alkali concentration of the first red mud dump return water to obtain the second red mud dump return water. The second red mud dump return water containing sodium sulfide is crystallized to separate sodium sulfide and the third red mud dump return water. The third red mud dump return water returns to the alumina production process and can be used as a washing liquid for the red mud of the alumina production process for recycling. The sodium sulfide is mixed with the sodium aluminate solution to purify the sodium aluminate solution and realize the recycling of the sodium sulfide to obtain a pure sodium aluminate solution. The second coal gasification obtained after the chemical reaction of the first coal gasification is returned to the alumina production process to be used as a roasting fuel for the alumina production process for recycling. Therefore, the red mud dump return water purifies the coal gasification and simultaneously prepares sodium sulfide, a purifier for sodium aluminate solution. The purified red mud dump return water and coal gasification are reused for the second time, realizing resource utilization. BRIEF DESCRIPTION OF THE DRAWINGS
[0025] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the present application.
[0026] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following is a brief introduction to the drawings required for use in the embodiments or the description of the prior art. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.
[0027] Figure 1 A flow chart of a method for resource utilization of red mud dump return water in coordination with coal gasification provided in an embodiment of the present application. DETAILED DESCRIPTION
[0028] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application.
[0029] Various embodiments of the present application may be presented in the form of a range; it should be understood that the description in the form of a range is only for convenience and brevity, and should not be understood as a rigid limitation on the scope of the present application; therefore, the range description should be considered to have specifically disclosed all possible sub-ranges and single numerical values within the range. For example, the range description from 1 to 6 should be considered to have specifically disclosed sub-ranges, such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., as well as single numbers within the range, such as 1, 2, 3, 4, 5 and 6, which apply regardless of the range. In addition, whenever a numerical range is indicated herein, it is meant to include any cited number (fractional or integer) within the indicated range.
[0030] In the present application, unless otherwise specified, the directional words used, such as "upper" and "lower", refer specifically to the directions of the drawings in the accompanying drawings. In addition, in the description of the specification of the present application, the terms "include", "comprise", etc. mean "including but not limited to". In this article, relational terms such as "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. In this article, "and / or" describes the association relationship of associated objects, indicating that three relationships may exist. For example, A and / or B can represent: the existence of A alone, the existence of A and B at the same time, and the existence of B alone. Among them, A and B can be singular or plural.
[0031] Unless otherwise specified, various raw materials, reagents, instruments and equipment used in this application can be purchased from the market or prepared by existing methods.
[0032] In the first aspect, the embodiments of the present application provide a method for resource utilization of red mud dump return water in coordination with coal gasification. Figure 1 A schematic diagram of a method for resource utilization of red mud dump return water and coal gasification provided in an embodiment of the present application; see Figure 1 , the method comprising:
[0033] S1, chemically reacting the first red mud dump return water with the first coal-based gas to obtain the second red mud dump return water containing sodium sulfide and the second coal-based gas;
[0034] S2, crystallizing the second red mud dump return water containing sodium sulfide to obtain sodium sulfide and the third red mud dump return water;
[0035] S3, mixing sodium sulfide with the sodium aluminate solution so that the sodium sulfide is used as a purifier of the sodium aluminate solution for recycling to obtain a pure sodium aluminate solution;
[0036] S4, returning the return water from the third red mud dump to the alumina production process to serve as a washing liquid for the red mud in the alumina production process for recycling; and
[0037] S5. Returning the second coal-to-gas to the alumina production process to serve as roasting fuel for the alumina production process for recycling.
[0038] The red mud dump is a waste residue produced in the process of alumina production, and the red mud dump return water comes from this dump. In the embodiment of the present application, the sodium hydroxide in the first red mud dump return water reacts chemically with the hydrogen sulfide and carbonyl sulfide in the first coal-to-gasification to generate sodium sulfide, thereby reducing the alkali concentration of the first red mud dump return water to obtain the second red mud dump return water, and the second red mud dump return water containing sodium sulfide is crystallized to separate sodium sulfide and the third red mud dump return water, which is returned to the alumina production process and can be used as a washing liquid for the red mud in the alumina production process for recycling. Therefore, in line with the principle of no-waste factory, the dump return water will return to the process for washing red mud, so reducing the NaOH in the dump return water is beneficial to red mud washing and also beneficial to alumina production. In the process of alumina production, impurity ions such as Mn, Pb, Cr, Cd, Zn, and Cu in bauxite enter the sodium aluminate solution together, which has an adverse effect on alumina production. Divalent sulfides can precipitate these metal ions to purify the solution and improve product quality. The NaOH in the red mud dump return water is used to oxidize and recover H2S in the coal gas to generate Na2S, which not only reduces the alkali concentration in the dump return water to facilitate red mud washing, but also allows the generated Na2S to be used for the purification of sodium aluminate solution. Mixing sodium sulfide with sodium aluminate solution can purify the sodium aluminate solution and realize the recycling of sodium sulfide, thereby obtaining a pure sodium aluminate solution; the second coal gas obtained after the chemical reaction of the first coal gas is returned to the alumina production process to be used as a roasting fuel for the alumina production process for recycling; therefore, the red mud dump return water purifies the coal gas and simultaneously prepares sodium sulfide, a purifier for sodium aluminate solution, realizing resource utilization. This method of purifying coal gas organically combines alumina production with coal gas desulfurization technology, and complements each other, reduces costs, and simplifies the process.
[0039] The reaction of using sodium hydroxide in the return water of the first red mud dump to purify coal gas is as follows:
[0040] H2S+2NaOH(excess)=Na2S+2H2O
[0041] COS+4NaOH=Na2CO3+Na2S+2H2O
[0042] The reaction of using Na2S to precipitate metal impurities is as follows:
[0043] 2Cr 2+ +3Na2S=2Cr(OH)3↓+3H2S+2Na +
[0044] Mn 2+ +Na2S=MnS↓+2Na +
[0045] Pb 2+ +Na 2 S=PbS↓+2Na +
[0046] In some embodiments, the flow rate of the red mud dump return water is 10 L / h to 35 L / h.
[0047] In some embodiments, the flow rate of the red mud dump return water is 20 L / h to 29 L / h.
[0048] In some embodiments, the flow rate of the first coal-to-gas is 0.8 m 3 / h~1.5m 3 / h.
[0049] In some embodiments, the flow rate of the first coal-to-gas is 1 m 3 / h.
[0050] In the embodiment of the present application, the flow rate of the red mud dump return water is 10L / h to 35L / h, which can achieve full reaction and recovery of H2S and COS of the first coal gasification, and then achieve effective purification of the first coal gasification. If the flow rate of the red mud dump return water is higher than 35L / h, although the purification effect of the first coal gasification can be improved, the concentration of sodium sulfide in the second red mud dump return water will be low, and it will be difficult to separate the second red mud dump return water and sodium sulfide, and thus it will be difficult to recycle sodium sulfide; if the flow rate of the red mud dump return water is lower than 10L / h, it may lead to a reduced reaction and recovery effect of H2S of the first coal gasification, and the concentration of sodium sulfide in the second red mud dump return water will be high, which will accumulate in the alumina production process later, thereby possibly introducing impurities. Similarly, the flow rate of the first coal gasification can be 0.8m 3 / h~1.5m 3 / h, which can coordinate with the flow rate of red mud dump return water to achieve full reaction and recovery of H2S and COS in the first coal-to-gasification. Exemplarily, the flow rate of the red mud dump return water can be 10L / h, 12L / h, 14L / h, 16L / h, 18L / h, 20L / h, 22L / h, 24L / h, 26L / h, 28L / h, 30L / h, 32L / h, 34L / h, 35L / h, 20L / h, 21L / h, 23L / h, 25L / h, 27L / h, 29L / h, etc.; the flow rate of the first coal-to-gasification can be 0.8m 3 / h、0.9m 3 / h、1.0m 3 / h、1.1m 3 / h、1.2m 3 / h、1.3m 3 / h、1.4m 3 / h、1.5m 3 / h, etc.
[0051] In some embodiments, the chemical reaction of the first red mud dump return water with the first coal-based gas to obtain the second red mud dump return water containing sodium sulfide and the second coal-based gas comprises:
[0052] The first red mud dump return water and the first coal gasification are chemically reacted to obtain the second red mud dump return water containing sodium sulfide and the second coal gasification; wherein the first red mud dump return water is introduced from the top of the reaction device from top to bottom, and the first coal gasification is introduced from the bottom to top of the reaction device, and the reaction device has a set height-to-diameter ratio.
[0053] In some embodiments, the aspect ratio is set to be 4 to 4.5.
[0054] In the embodiment of the present application, the first red mud dump return water is introduced from the top of the reaction device from top to bottom, and the first coal-based gas is introduced from the bottom of the reaction device from bottom to top. The first red mud dump return water and the first coal-based gas are fully contacted for chemical reaction. The height-to-diameter ratio can be set to 4-4.5, and the reaction material has a long stroke, giving the first red mud dump return water and the first coal-based gas sufficient contact time, thereby ensuring the full reaction and recovery effect of H2S of the first coal-based gas. Exemplarily, the set height-to-diameter ratio can be 4, 4.1, 4.2, 4.3, 4.4, 4.5, etc.
[0055] In some embodiments, the first red mud dump backwater is introduced by spraying.
[0056] In the embodiment of the present application, the first red mud dump return water is introduced by the spraying method, which can increase the contact area between the first red mud dump return water and the first coal-based gas, and improve the full reaction and recovery effect of H2S and COS of the first coal-based gas. The spraying method mainly utilizes the first red mud dump return water to contact with the first coal-based gas, and transfers the first coal-based gas from the gas phase to the liquid phase through the gas-liquid mass transfer process, thereby achieving the purpose of purifying the first coal-based gas. During the spraying process, the absorbent is sprayed from the nozzle in the form of small droplets to form a dispersed phase, and the first coal-based gas contacts it as a continuous phase to undergo a chemical reaction.
[0057] In some embodiments, the sodium sulfide is mixed with the sodium aluminate solution so that the sodium sulfide is used as a purifier of the sodium aluminate solution for recycling to obtain a pure sodium aluminate solution, comprising:
[0058] Mixing sodium sulfide with a sodium aluminate solution so that the sodium sulfide is used as a purifier of the sodium aluminate solution for recycling to obtain a pure sodium aluminate solution;
[0059] The pure sodium aluminate solution is decomposed to obtain aluminum hydroxide; wherein the whiteness of the aluminum hydroxide is greater than 95%.
[0060] In the embodiment of the present application, the yard return water in the alumina production process is used to purify coal gas, and while removing H2S and COS, the resulting purifier (Na2S) is used to purify the sodium aluminate solution, and the pure sodium aluminate solution is decomposed to obtain aluminum hydroxide, and the whiteness of the aluminum hydroxide can be greater than 95. For example, the whiteness of the aluminum hydroxide can be 96%, 96.5%, 97%, 97.5%, etc.
[0061] In some embodiments, the H2S content in the first coal-to-gas is 1830 mg / m 3 ~2260 mg / m 3 The H2S content in the second coal-to-gas is <5 mg / m 3 .
[0062] In the embodiment of the present application, the H2S content in the first coal-to-gas can be 1830 mg / m 3 , 1850mg / m 3 , 1870mg / m 3 , 1890mg / m 3 , 1900mg / m 3 , 1920mg / m 3 , 1940mg / m 3 , 1960mg / m 3 , 1980mg / m 3 , 2000mg / m 3 , 2050mg / m3 , 2100mg / m 3 , 2150mg / m 3 , 2200mg / m 3 , 2260mg / m 3 etc.; the H2S content in the second coal-to-gas can be 4.5 mg / m 3 4.3mg / m 3 , 4mg / m 3 , 3.8mg / m 3 , 3.5mg / m 3 wait.
[0063] In summary, the method for resource utilization of red mud dump return water in conjunction with coal-to-gas provided in the embodiment of the present application has the following advantages:
[0064] 1. The first red mud dump return water and the first coal gasification reaction
[0065] The first red mud dump return water contains sodium hydroxide (NaOH), and the coal gas contains hydrogen sulfide (H2S) and carbonyl sulfide (COS). The first red mud dump return water reacts with the coal gas to convert the sulfur-containing pollutants in the coal gas into sodium sulfide (Na2S). At the same time, the sodium hydroxide is consumed, reducing the alkali concentration of the first red mud dump return water to obtain the second red mud dump return water.
[0066] 2. Purification of sodium aluminate solution with sodium sulfide
[0067] Sodium aluminate solution may contain some impurities during the alumina production process. When sodium sulfide (Na2S) is mixed with sodium aluminate solution, sodium sulfide can react with certain impurities in the solution to form precipitates or other easily separated substances, thereby purifying the sodium aluminate solution and obtaining a pure sodium aluminate solution, thus realizing the recycling of sodium sulfide in the alumina production process, improving resource utilization and helping to improve the quality of alumina products.
[0068] 3. Recycling of the third red mud dump return water and the second coal-to-gasification
[0069] The third red mud dump return water: return it to the alumina production process as red mud washing liquid. Red mud is the waste residue in the alumina production process, containing a certain amount of recyclable substances such as sodium aluminate and sodium hydroxide. The third red mud dump return water washing red mud can further recover the useful components in it, while reducing the use of new water, reducing production costs and benefiting the environment. The second coal gas recycling: the second coal gas can be used as fuel for the alumina roasting furnace, thereby realizing the full utilization of coal gas resources.
[0070] 4. Collaborative Utilization of Resources
[0071] The coordinated treatment and utilization of two different sources of waste or resources, red mud dump return water and coal-to-gas, has been achieved. On the one hand, the alkalinity of red mud dump return water is used to treat sulfur-containing pollutants in coal-to-gas to obtain valuable sodium sulfide; on the other hand, the treated return water and coal-to-gas can be returned to the alumina production process and other recycling links, respectively, improving the resource circulation efficiency of the entire industrial system and reducing waste emissions.
[0072] 5. Reduce production costs
[0073] By reusing the return water from the second red mud dump as washing liquid, water resource consumption and treatment costs in the alumina production process are saved. At the same time, the sodium sulfide generated by the reaction of the red mud dump return water and coal gasification is used to purify the sodium aluminate solution, which reduces the cost of purchasing special purifiers. The recycling of coal gas can also bring certain economic benefits, such as increasing income through energy recovery after roasting or chemical product synthesis, thereby reducing the comprehensive cost of alumina production and coal gasification.
[0074] 6. Significant environmental benefits
[0075] It effectively reduces the emission of pollutants such as hydrogen sulfide and carbonyl sulfide in coal-to-gasification, and reduces the pollution to the atmospheric environment. At the same time, it improves the resource utilization rate of red mud dump return water and coal-to-gasification, and reduces the amount of waste generated and the difficulty of treatment.
[0076] In general, the resource utilization method of red mud dump return water and coal-to-gas has a good technological principle foundation, and has obvious advantages and application value in many aspects such as resource utilization, cost control and environmental protection, providing an innovative and effective solution for the resource treatment of waste in related industrial fields.
[0077] The present application will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are intended only to illustrate the present application and are not intended to limit the scope of the present application. The experimental methods for the unrecorded specific conditions in the following examples are usually measured according to national standards. If there is no corresponding national standard, then carry out according to general international standards, normal conditions or according to the conditions recommended by the manufacturer.
[0078] Example 1
[0079] The materials involved are as follows:
[0080] Coal-to-gas: H2S content 2263mg / m 3 ;
[0081] Yard return water: Al2O3 content 6.66g / l, Na2Ok content 11.4g / l, Na2Oc content 3.59g / l.
[0082] A method for resource utilization of red mud dump return water in coordination with coal-to-gas, comprising:
[0083] Chemically reacting the first red mud dump return water with the first coal-based gas to obtain the second red mud dump return water containing sodium sulfide and the second coal-based gas;
[0084] Specifically, 20L of yard return water is first injected into the bottom of the reaction device, and then the coal-to-gas flow rate is increased by 1m 3 / h is introduced from the bottom of the device, and the yard return water flow rate is 20L / h from the top of the device. The second coal-to-gas obtained after the chemical reaction is passed through the top of the device, and the yard return water after absorbing hydrogen sulfide flows out from the bottom of the device. The height-to-diameter ratio of the reaction device is:
[0085] crystallize the second red mud dump return water containing sodium sulfide to obtain sodium sulfide and the third red mud dump return water;
[0086] Mixing sodium sulfide with sodium aluminate solution so that the sodium sulfide is used as a purifier of the sodium aluminate solution for recycling to obtain a pure sodium aluminate solution;
[0087] Decomposing the pure sodium aluminate solution to obtain aluminum hydroxide;
[0088] Returning the return water from the third red mud dump to the alumina production process as washing liquid for the red mud in the alumina production process for recycling; and
[0089] The second coal-to-gas is used as roasting fuel for the roasting furnace of the alumina enterprise, and is roasted for recycling.
[0090] Example 2
[0091] The materials involved are as follows:
[0092] Coal-to-gas: H2S content 2263mg / m 3 ;
[0093] Yard return water: Al2O3 content 6.66g / l, Na2Ok content 11.4g / l, Na2Oc content 3.59g / l.
[0094] A method for resource utilization of red mud dump return water in coordination with coal-to-gas, comprising:
[0095] Chemically reacting the first red mud dump return water with the first coal-based gas to obtain the second red mud dump return water containing sodium sulfide and the second coal-based gas;
[0096] Specifically, 20L of yard return water is first injected into the bottom of the reaction device, and then the coal-to-gas flow rate is increased by 1m 3 / h is introduced from the bottom of the device, and the yard return water flow rate is 20L / h from the top of the device. The second coal-to-gas obtained after the chemical reaction is passed through the top of the device, and the yard return water after absorbing hydrogen sulfide flows out from the bottom of the device; the height-to-diameter ratio of the reaction device is 0.3*1.35m;
[0097] crystallize the second red mud dump return water containing sodium sulfide to obtain sodium sulfide and the third red mud dump return water;
[0098] Mixing sodium sulfide with sodium aluminate solution so that the sodium sulfide is used as a purifier of the sodium aluminate solution for recycling to obtain a pure sodium aluminate solution;
[0099] Decomposing the pure sodium aluminate solution to obtain aluminum hydroxide;
[0100] Returning the return water from the third red mud dump to the alumina production process as washing liquid for the red mud in the alumina production process for recycling; and
[0101] The second coal-to-gas is used as roasting fuel for the roasting furnace of the alumina enterprise, and is roasted for recycling.
[0102] Example 3
[0103] The materials involved are as follows:
[0104] Coal-to-gas: H2S content 2263mg / m 3 ;
[0105] Yard return water: Al2O3 content 6.66g / l, Na2Ok content 11.4g / l, Na2Oc content 3.59g / l.
[0106] A method for resource utilization of red mud dump return water in coordination with coal-to-gas, comprising:
[0107] Chemically reacting the first red mud dump return water with the first coal-based gas to obtain the second red mud dump return water containing sodium sulfide and the second coal-based gas;
[0108] Specifically, 15L of yard return water is first injected into the bottom of the reaction device, and then the coal-to-gas flow rate is increased by 1m 3 / h is introduced from the bottom of the device, and the yard return water flow rate is 23L / h from the top of the device. The second coal-to-gas obtained after the chemical reaction is passed through the top of the device, and the yard return water after absorbing hydrogen sulfide flows out from the bottom of the device. The height-to-diameter ratio of the reaction device is:
[0109] crystallize the second red mud dump return water containing sodium sulfide to obtain sodium sulfide and the third red mud dump return water;
[0110] Mixing sodium sulfide with sodium aluminate solution so that the sodium sulfide is used as a purifier of the sodium aluminate solution for recycling to obtain a pure sodium aluminate solution;
[0111] Decomposing the pure sodium aluminate solution to obtain aluminum hydroxide;
[0112] Returning the return water from the third red mud dump to the alumina production process as washing liquid for the red mud in the alumina production process for recycling; and
[0113] The second coal-to-gas is used as roasting fuel for the roasting furnace of the alumina enterprise, and is roasted for recycling.
[0114] Example 4
[0115] The materials involved are as follows:
[0116] Coal-to-gas: H2S content 2263mg / m 3 ;
[0117] Yard return water: Al2O3 content 6.66g / l, Na2Ok content 11.4g / l, Na2Oc content 3.59g / l.
[0118] A method for resource utilization of red mud dump return water in coordination with coal-to-gas, comprising:
[0119] Chemically reacting the first red mud dump return water with the first coal-based gas to obtain the second red mud dump return water containing sodium sulfide and the second coal-based gas;
[0120] Specifically, 20L of yard return water is first injected into the bottom of the reaction device, and then the coal-to-gas flow rate is increased by 1m 3 / h is introduced from the bottom of the device, and the yard return water flow rate is 26L / h from the top of the device. The second coal-to-gas obtained after the chemical reaction is passed out from the top of the device, and the yard return water after absorbing hydrogen sulfide flows out from the bottom of the device. The height-to-diameter ratio of the reaction device is:
[0121] crystallize the second red mud dump return water containing sodium sulfide to obtain sodium sulfide and the third red mud dump return water;
[0122] Mixing sodium sulfide with sodium aluminate solution so that the sodium sulfide is used as a purifier of the sodium aluminate solution for recycling to obtain a pure sodium aluminate solution;
[0123] Decomposing the pure sodium aluminate solution to obtain aluminum hydroxide;
[0124] Returning the return water from the third red mud dump to the alumina production process as washing liquid for the red mud in the alumina production process for recycling; and
[0125] The second coal-to-gas is used as roasting fuel for the roasting furnace of the alumina enterprise, and is roasted for recycling.
[0126] Example 5
[0127] The materials involved are as follows:
[0128] Coal-to-gas: H2S content 2263mg / m 3 ;
[0129] Yard return water: Al2O3 content 6.66g / l, Na2Ok content 11.4g / l, Na2Oc content 3.59g / l.
[0130] A method for resource utilization of red mud dump return water in coordination with coal-to-gas, comprising:
[0131] Chemically reacting the first red mud dump return water with the first coal-based gas to obtain the second red mud dump return water containing sodium sulfide and the second coal-based gas;
[0132] Specifically, 25L of yard return water is first injected into the bottom of the reaction device, and then the coal-to-gas flow rate is increased by 1m 3 / h is introduced from the bottom of the device, and the yard return water flow rate is 29L / h from the top of the device. The second coal-to-gas obtained after the chemical reaction is passed out from the top of the device, and the yard return water after absorbing hydrogen sulfide flows out from the bottom of the device. The height-to-diameter ratio of the reaction device is:
[0133] crystallize the second red mud dump return water containing sodium sulfide to obtain sodium sulfide and the third red mud dump return water;
[0134] Mixing sodium sulfide with sodium aluminate solution so that the sodium sulfide is used as a purifier of the sodium aluminate solution for recycling to obtain a pure sodium aluminate solution;
[0135] Decomposing the pure sodium aluminate solution to obtain aluminum hydroxide;
[0136] Returning the return water from the third red mud dump to the alumina production process as washing liquid for the red mud in the alumina production process for recycling; and
[0137] The second coal-to-gas is used as roasting fuel for the roasting furnace of the alumina enterprise, and is roasted for recycling.
[0138] Comparative Example 1
[0139] The materials involved are as follows:
[0140] Coal-to-gas: H2S content 2263mg / m 3 ;
[0141] Yard return water: Al2O3 content 6.66g / l, Na2Ok content 11.4g / l, Na2Oc content 3.59g / l.
[0142] A method for resource utilization of red mud dump return water in coordination with coal-to-gas, comprising:
[0143] Chemically reacting the first red mud dump return water with the first coal-based gas to obtain the second red mud dump return water containing sodium sulfide and the second coal-based gas;
[0144] Specifically, 20L of yard return water is first injected into the bottom of the reaction device, and then the coal-to-gas flow rate is increased by 1m 3 / h is introduced from the bottom of the device, and the yard return water flow rate is 20L / h from the top of the device. The second coal-to-gas obtained after the chemical reaction is passed through the top of the device, and the yard return water after absorbing hydrogen sulfide flows out from the bottom of the device. The height-to-diameter ratio of the reaction device is:
[0145] crystallize the second red mud dump return water containing sodium sulfide to obtain sodium sulfide and the third red mud dump return water;
[0146] Mixing sodium sulfide with sodium aluminate solution so that the sodium sulfide is used as a purifier of the sodium aluminate solution for recycling to obtain a pure sodium aluminate solution;
[0147] Decomposing the pure sodium aluminate solution to obtain aluminum hydroxide;
[0148] Returning the return water from the third red mud dump to the alumina production process as washing liquid for the red mud in the alumina production process for recycling; and
[0149] The second coal-to-gas is used as roasting fuel for the roasting furnace of the alumina enterprise, and is roasted for recycling.
[0150] For Examples 1 to 5 and Comparative Example 1, gas samples and solution samples were taken for component analysis after the reaction was stably run for 30 minutes. The results are shown in Table 1.
[0151] Table 1 Treatment effect of the method of resource utilization of red mud dump return water and coal gasification
[0152]
[0153] From Table 1, it can be seen that the treatment effect of the method for resource utilization of red mud dump return water and coal gas provided in Examples 1 to 5 can achieve: the reaction rate (or absorption rate) of hydrogen sulfide is above 99%, and the hydrogen sulfide content of coal gas is as low as 5mg / m 3A relatively ideal effect was achieved. Among them, Example 4 is the most efficient and economical. In Comparative Example 1, the height-to-diameter ratio of the reaction device is small, the contact time between the first coal gasification and the first red mud dump return water is short, the chemical reaction is insufficient, the hydrogen sulfide absorption rate is lower than that of the embodiment, and the hydrogen sulfide gas content in the second coal gasification is seriously exceeded; and the amount of return water introduced into the first red mud dump is smaller than that of Examples 3 to 5, so the sodium sulfide content in Comparative Example 1 is high, indicating that the ratio of the first coal gasification and the first red mud dump return water affects the concentration of sodium sulfide in the second red mud dump return water.
[0154] One or more technical solutions in the embodiments of the present application also have at least the following technical effects or advantages:
[0155] (1) Recycling H2S from red mud dump return water and coal-to-gas, with simple process and flexible and controllable operation, simplifies the difficulty and operation complexity of coal-to-gas desulfurization process and reduces operating costs;
[0156] (2) The coal-to-gas is purified, eliminating the toxicity of coal-to-gas during transportation and ensuring transportation safety. At the same time, due to the high removal efficiency of hydrogen sulfide, its adverse effect on the particle size of alumina products in the flash roasting furnace is eliminated;
[0157] (3) H2S gas in coal-to-gas is recycled, improving resource utilization;
[0158] (4) The red mud dump backwater absorbs H2S gas, and the generated Na2S is used as a purifier for sodium aluminate solution and used in alumina production, thus achieving clean recycling of resources;
[0159] (5) After the coal gasification is purified by the return water from the storage yard, the alkali content of the return water is reduced, which is beneficial to improving the red mud washing efficiency.
[0160] The above description is only a specific implementation of the present application, so that those skilled in the art can understand or implement the present application. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to the embodiments shown herein, but will conform to the widest scope consistent with the principles and novel features applied for herein.
Claims
1. A method for resource utilization of red mud dump return water in coordination with coal-to-gas, the method comprising: Chemically reacting the first red mud dump return water with the first coal-based gas to obtain the second red mud dump return water containing sodium sulfide and the second coal-based gas; crystallize the second red mud dump return water containing sodium sulfide to obtain sodium sulfide and the third red mud dump return water; Mixing sodium sulfide with a sodium aluminate solution so that the sodium sulfide is used as a purifier of the sodium aluminate solution for recycling to obtain a pure sodium aluminate solution; Returning the return water from the third red mud dump to the alumina production process to serve as a washing liquid for the red mud in the alumina production process for recycling; as well as, The second coal-generated gas is returned to the alumina production process to be used as roasting fuel for the alumina production process for recycling.
2. The method according to claim 1, characterized in that The flow rate of the red mud dump return water is 10L / h to 35L / h.
3. The method according to claim 2, characterized in that The flow rate of the red mud dump return water is 20L / h to 29L / h.
4. The method according to claim 1, characterized in that: The flow rate of the first coal-to-gas is 0.8 m 3 / h~1.5m 3 / h.
5. The method according to claim 4, characterized in that The flow rate of the first coal-to-gas is 1m 3 / h.
6. The method according to claim 1, characterized in that The method of chemically reacting the first red mud dump return water with the first coal-based gas to obtain the second red mud dump return water containing sodium sulfide and the second coal-based gas comprises: The first red mud dump return water and the first coal gasification are chemically reacted to obtain the second red mud dump return water containing sodium sulfide and the second coal gasification; wherein the first red mud dump return water is introduced from the top of the reaction device from top to bottom, and the first coal gasification is introduced from the bottom to top of the reaction device, and the reaction device has a set height-to-diameter ratio.
7. The method according to claim 6, characterized in that The aspect ratio is set to be 4 to 4.
5.
8. The method according to claim 6, characterized in that The return water of the first red mud dump is introduced by spraying.
9. The method according to claim 1, characterized in that: The H2S content in the first coal-fired gas is 1830 mg / m 3 ~2260 mg / m 3 The H2S content in the second coal-to-gas is <5 mg / m 3 .
10. The method according to claim 1, characterized in that The sodium sulfide is mixed with the sodium aluminate solution so that the sodium sulfide is used as a purifier of the sodium aluminate solution for recycling to obtain a pure sodium aluminate solution, comprising: Mixing sodium sulfide with a sodium aluminate solution so that the sodium sulfide is used as a purifier of the sodium aluminate solution for recycling to obtain a pure sodium aluminate solution; The pure sodium aluminate solution is decomposed to obtain aluminum hydroxide; wherein the whiteness of the aluminum hydroxide is greater than 95%.