Treatment procedure for reducing carbon dioxide emission by using red mud waste
By converting red mud waste into a carbon dioxide absorbent for flue gas treatment, the environmental hazards of red mud are mitigated, and carbon dioxide emissions are reduced, contributing to net zero carbon emissions and providing a carbon source for aquatic photosynthesis.
Patent Information
- Application Number
- CN202310684654.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2023-06-09
- Publication Date
- 2024-12-10
AI Technical Summary
The disposal of red mud waste from aluminum smelting poses significant environmental hazards due to its alkalinity, corrosiveness, and potential for heavy metal and radioactive contamination, leading to land waste and air pollution, with no effective treatment methods currently in place.
A treatment procedure is developed to convert red mud waste into a carbon dioxide absorbent by mixing it with water to dissolve alkaline substances, producing a red mud solid-liquid mixture or elutriation liquid, which is then used in a water scrubber to absorb CO2 from flue gas, with optional filtration to remove solid particles.
The process effectively reduces carbon dioxide emissions and transforms harmful red mud into a carbon source for aquatic photosynthesis, achieving net zero carbon emissions and mitigating environmental pollution.
Smart Images
Figure CN119098025A_ABST
Abstract
Description
[Technical field]
[0001] The present invention relates to a treatment procedure for reducing carbon dioxide emissions by using red mud waste, which is a preparation treatment procedure for producing carbon dioxide absorbent by using red mud waste to effectively reduce the overall red mud waste, and an application treatment procedure for using the produced carbon dioxide absorbent to leach and absorb carbon dioxide contained in flue gas flow to effectively reduce carbon dioxide emissions. [Background technology]
[0002] In the aluminum smelting process of producing metallic aluminum, "red mud waste" will be produced. For the convenience of explanation, "red mud waste" will be referred to as "red mud" below, that is, in this specification, the term "red mud" is essentially equivalent to "red mud waste". Aluminum has a very active chemical property, so it is difficult for us to find its metallic form in nature. Therefore, the primary task of the aluminum smelting industry is to try to refine (convert) various aluminum compounds into elemental aluminum. At present, aluminum is basically obtained by electrolyzing aluminum oxide, so the production of aluminum oxide has become a very important front-end operation for the production of aluminum. Aluminum oxide is commonly found in bauxite in nature, but the composition of bauxite is not only aluminum oxide. Even if it is bauxite with a high aluminum oxide content, the weight percentage of aluminum oxide is often only about 60%, and the rest is "silicon dioxide", "iron trioxide", "titanium dioxide" and other compounds. Therefore, in order to produce metallic aluminum, it is necessary to first try to separate aluminum oxide from other compounds in bauxite. The actual process of separating alumina from bauxite is that the mined bauxite must first be crushed and ground to turn large pieces of bauxite into small particles of powder. The bauxite powder is then added to a high-concentration sodium hydroxide aqueous solution. Under high temperature and pressure, the alumina in the bauxite reacts with sodium hydroxide to form water-soluble sodium aluminate. The other components do not react with alkali and therefore remain in solid form. The alkaline solution containing sodium aluminate is then cooled and a small amount of aluminum hydroxide is added to cause the sodium aluminate in the solution to gather around the aluminum hydroxide, so that a large amount of aluminum hydroxide will precipitate from the solution. The aluminum hydroxide is then calcined at high temperature to become alumina, and then electrolyzed to obtain metallic aluminum.
[0003] A critical step in the above-mentioned production process of separating alumina is to use alkaline solution to produce alumina, so as to separate alumina from other components in bauxite. In other words, solid compounds such as silicon dioxide, ferric oxide, titanium dioxide, etc. that cannot be dissolved by alkaline solution will be filtered out with the sodium hydroxide solution. The main component of ferric oxide is dark red, so the final waste is a dark red or brick red mud-like fluid, which is called "red mud".
[0004] After the "red mud" is separated from the bauxite, the aluminum smelting plant may generally adopt "wet stacking" as a passive treatment. "Wet stacking" is to discharge the red mud into a pre-excavated pool, and let the water in the pool evaporate naturally to leave solid red mud; or "dry stacking" is also a passive treatment. "Dry stacking" is to first remove the water in the red mud and then stack the solid red mud in the open air. However, whether it is wet stacking or dry stacking, it is at best passive stacking. In fact, no treatment is done to the red mud at all. Therefore, the harm of red mud to nature still exists and will not weaken or disappear with stacking. It is estimated that there are more than 2 billion tons of red mud temporarily stored in the world without proper treatment.
[0005] Because red mud contains alkaline substances such as sodium and potassium, solid red mud or the liquid after red mud washing is alkaline. Therefore, if there is no treatment, red mud will cause serious harm to the nature as follows:
[0006] 1. A lot of land is wasted in order to pile up red mud, and the wasted land will only increase. Red mud contains a large amount of highly corrosive sodium hydroxide, and some of it also contains toxic heavy metals and even radioactive elements. Therefore, the land where red mud has been piled will not be able to be used for other purposes for a long time.
[0007] 2. To produce 1 ton of aluminum ingots, about 2.5 tons of red mud are generated. The output is very large. When it is piled up, it is generally left on the surface, causing the soluble sodium salts and harmful heavy metals and even radioactive elements in the red mud to seep into the ground for a long time. At the same time, the stench drifts in the air, causing serious environmental pollution and endangering human health. [Summary of the invention]
[0008] The objectives of the present invention are: 1. To provide a preparation and treatment procedure that can utilize red mud waste to prepare and produce carbon dioxide absorbent, so as to effectively reduce the overall red mud waste. 2. To provide an application and treatment procedure that can utilize the produced carbon dioxide absorbent to leach and absorb carbon dioxide contained in flue gas flow, so as to effectively reduce carbon dioxide emissions.
[0009] To achieve the above-mentioned purpose, the present invention provides a processing procedure for preparing a carbon dioxide absorbent using red mud waste, which is to mix a solid red mud waste with a water liquid for washing, wherein the pH value of the solid red mud waste is between 9.4 and 10.7. If the mass of the water liquid 20 is 100%, the mass of the solid red mud waste is 1.0% to 10.0%. During the washing process, alkaline substances such as sodium, potassium, calcium, and magnesium contained in the red mud waste are washed and dissolved in the water liquid to produce a red mud solid-liquid mixed liquid, which can be used as the carbon dioxide absorbent.
[0010] The present invention further provides a processing procedure for preparing a carbon dioxide absorbent using red mud waste, which is to mix and elute a solid red mud waste with a water liquid, wherein the pH value of the solid red mud waste is between 9.4 and 10.7. If the mass of the water liquid 20 is 100%, the mass of the solid red mud waste is 1.0% to 10.0%. During the elutriation process, alkaline substances such as sodium, potassium, calcium, and magnesium contained in the red mud waste are elutriated and dissolved in the water liquid to produce a red mud solid-liquid mixed liquid. The red mud solid-liquid mixed liquid is pumped through a filtering device to remove solid particles, and after passing through the filtering device, a red mud elutriated liquid is produced. The red mud elutriated liquid can be used as the carbon dioxide absorbent.
[0011] In the above-mentioned process of preparing a carbon dioxide absorbent from red mud waste, the red mud solid-liquid mixture and / or the red mud washing liquid can be mixed with red mud seepage water having a pH value (pH value) of 9.5 or above and used as a carbon dioxide absorbent.
[0012] The present invention also provides an application processing procedure for reducing carbon dioxide emissions by using a carbon dioxide absorbent, wherein the carbon dioxide absorbent generated above is introduced into a water scrubber, and the flue gas flow rising through the water scrubber is washed from top to bottom, thereby absorbing and removing the carbon dioxide content in the flue gas flow.
[0013] In the above-mentioned application treatment procedure of reducing carbon dioxide emissions by using carbon dioxide absorbent, the gas-liquid volume ratio of the water scrubber is between 35 and 65, and the residence time of the flue gas in the water scrubber is between 0.6 and 2.0 seconds.
[0014] In the above-mentioned application and treatment procedure for reducing carbon dioxide emissions by using carbon dioxide absorbents, the carbon dioxide absorbent can be guided out of a temporary retention tank before and after entering the water scrubber for elution; the flue gas flow is in a guided state when passing upward after being eluted through the inside of the water scrubber. In the above-mentioned application and treatment procedure for reducing carbon dioxide emissions by using carbon dioxide absorbents, the water scrubber can be set to one to four sections connected in series, and the flue gas flow after elution by the first section of the water scrubber is guided into the inside of the next section of the water scrubber for ascent, and at the same time, the carbon dioxide absorbent is guided into each section of the water scrubber to perform an up-to-down elution action on the flue gas flow rising through the water scrubber to absorb and remove the carbon dioxide content in the flue gas flow.
[0015] In the above-mentioned application process of reducing carbon dioxide emission by using carbon dioxide absorbent, the removal rate of carbon dioxide contained in the flue gas stream by each water scrubber is between 36% and 54%, with an average of 45% (n=7).
[0016] In the above-mentioned application treatment procedure of reducing carbon dioxide emissions by using a carbon dioxide absorbent, after the carbon dioxide contained in the flue gas flow is absorbed by the carbon dioxide absorbent, it will react to produce carbonates or bicarbonates. Therefore, after the carbonates or bicarbonates dissolved in the liquid are separated from the toxic and harmful heavy metals, the harmless carbonates or bicarbonates can be discharged into the ocean and become a carbon source for photosynthesis of aquatic plants in the ocean.
[0017] The advantages and beneficial effects of the present invention are:
[0018] 1. Using red mud waste to prepare a red mud solid-liquid mixture, and using the red mud solid-liquid mixture as a carbon dioxide absorbent;
[0019] 2. Using red mud waste to prepare a red mud solid-liquid mixture, filtering the red mud solid-liquid mixture to obtain a red mud elutriation liquid, and using the red mud elutriation liquid as a carbon dioxide absorbent;
[0020] 3. The red mud solid-liquid mixture or the red mud washing liquid can be added with "red mud seepage water" with a pH value (pH value) of more than 9.5 and mixed to be used as a carbon dioxide absorbent;
[0021] 4. The red mud solid-liquid mixture or the red mud washing liquid is used as a carbon dioxide absorbent and guided into the first to fourth stage water washing towers to fully wash the rising flue gas flow to absorb and remove the carbon dioxide content in the flue gas flow, thereby contributing to the net zero carbon emission action.
Brief Description of the Drawings
[0022] Figure 1 This is a schematic diagram of the first preparation process of the present invention for preparing a carbon dioxide absorbent using red mud.
[0023] Figure 2 It is a schematic diagram of the application processing procedure of the present invention using the generated carbon dioxide absorbent to wash the flue gas flow in a water washing tower.
[0024] Figure 3 It is a schematic diagram of a continuous application treatment procedure in which the water washing tower in the present invention is configured as four sections connected in series.
[0025] Figure 4 This is a schematic diagram of the second preparation process of the present invention for preparing a carbon dioxide absorbent using red mud.
[0026] The numbers in the figure are explained as follows:
[0027] Solid red mud waste 10 Water 20
[0028] Red mud solid-liquid mixture 30 Liquid pump 40
[0029] Liquid pump 40a Water washing tower 50
[0030] Water washing tower 51 Water washing tower 52
[0031] Water washing tower 53 Filter device 60
[0032] Red mud washing liquid 70 Liquid pump 80
[0033] Infusion pipeline Tb1 Infusion pipeline Tb2
[0034] Inlet pipeline Tb3 Gas pipeline Tb4
[0035] Liquid outlet pipe Tb5 Liquid outlet pipe Tb6
[0036] Slot A Slot B
[0037] Large collection tank C [Specific implementation method]
[0038] In view of the fact that red mud waste is essentially bound to be produced and exist, the present invention develops a treatment procedure for reducing carbon dioxide emissions using red mud waste, so as to contribute to the "net zero carbon emission" action. It is known that the pH value of red mud is between 9.4 and 10.7, with an average of 10.4, which means that the nature of red mud waste is alkaline. Now, the present invention is to study the use of the red mud waste to first prepare a carbon dioxide absorbent, which is used to leach the flue gas flow during the flue gas flow emission process to absorb the carbon dioxide contained in the flue gas flow, which can significantly reduce carbon emissions. Therefore, the front end of the present invention is the preparation process of the carbon dioxide absorbent, and the back end is the application process of the carbon dioxide absorbent.
[0039] The preparation of the carbon dioxide absorbent can be carried out in two processing procedures. For the first processing procedure, please refer to Figure 1As shown, firstly, a solid red mud waste 10 is selected as a material, and the pH value of the solid red mud waste 10 is between 9.4 and 10.7. Then, the solid red mud waste 10 is mixed and washed with a water liquid 20. If the mass of the water liquid 20 is 100%, the mass of the solid red mud waste 10 is 1.0% to 10.0%. In the process of mixing and washing the solid red mud waste 10 and the water liquid 20, the alkaline substances such as sodium, potassium, calcium, and magnesium contained in the red mud waste 10 are washed out and dissolved in the water liquid 20. At this time, the washing liquid is directly a red mud solid-liquid mixed liquid 30. Because the mass ratio of the solid red mud waste 10 to the water 20 is 1.0% to 10.0%: 100%, after the washing process, the alkaline substances such as sodium, potassium, calcium, and magnesium contained in the solid red mud waste 10 can be fully washed out and dissolved in the red mud solid-liquid mixture 30. In other words, the red mud solid-liquid mixture 30 is a solid-liquid mixture, but the liquid mass ratio accounts for more than 90% of the red mud solid-liquid mixture 30, and a high amount of alkaline substances such as sodium, potassium, calcium, and magnesium are dissolved in the liquid. As for the solid, it is a tiny powdery substance that cannot be dissolved in the liquid after the solid red mud waste 10 is fully washed, and the mass ratio accounts for a small part of the red mud solid-liquid mixture 30. The red mud solid-liquid mixture 30 produced after the above-mentioned treatment procedure is a carbon dioxide absorbent claimed by the present invention.
[0040] Then, the red mud solid-liquid mixture 30 is used as a carbon dioxide absorbent to wash the flue gas flow during the flue gas flow discharge process to absorb the carbon dioxide contained in the flue gas flow. For an application process, please refer to Figure 2As shown, a liquid pump 40 is mainly used to pump the red mud solid-liquid mixture 30 into a temporary retention tank A and a temporary retention tank B through a liquid infusion pipeline Tb1, that is, the red mud solid-liquid mixture 30 is first injected into the temporary retention tanks A and B to wait for use. During the process, the pH value (pH value) of the red mud solid-liquid mixture 30 in the temporary retention tanks A and B is frequently detected. When the pH value (pH value) of the red mud solid-liquid mixture 30 is measured to drop to 8.0-8.3, appropriate response will be performed. After an appropriate amount of the red mud solid-liquid mixture 30 is injected into the temporary retention tanks A and B, the temporary retention tank A (or the temporary retention tank B) can be selectively used first, and the red mud solid-liquid mixture 30 in the temporary retention tank A (or the temporary retention tank B) is pumped and guided to the upper side wall of a water washing tower 50 by a liquid delivery pipeline Tb2, and the inside of the water washing tower 50 is fully rinsed by a uniform water spraying plate provided in the water washing tower 50. At the same time, a flue gas flow is injected from the lower side wall of the water washing tower 50 through an inlet pipeline Tb3, so that the flue gas flow passes through the water washing tower 50 from bottom to top. During the process, the carbon dioxide, sulfur dioxide, nitrogen oxides, and particulate pollutants contained in the flue gas flow will be absorbed and removed by the red mud solid-liquid mixture 30 (i.e., a carbon dioxide absorbent). Therefore, when the flue gas flow is guided out from the top of the water washing tower 50 by a gas delivery pipeline Tb4, the carbon dioxide content in the gas flow has been greatly reduced. When the temporary retention tank A (or the temporary retention tank B) is selected to be used first, that is, although the other temporary retention tank B (or the temporary retention tank A) has been injected with the red mud solid-liquid mixture 30, it is temporarily stopped from being pumped into the washing tower 50 and is in a waiting state.
[0041] The gas-liquid volume ratio of the water scrubber 50 is preferably between 35 and 65, and the residence time of the flue gas (gas) in the water scrubber 50 is preferably between 0.6 and 2.0 seconds; the red mud solid-liquid mixture 30 enters the water scrubber 50 from the side wall above the water scrubber 50, and after being fully rinsed by the uniform watering plate provided in the water scrubber 50, the red mud solid-liquid mixture 30 that has absorbed carbon dioxide drips downward and converges The red mud solid-liquid mixture 30 is collected at the bottom of the water washing tower 50, and then the liquid can be guided out through a liquid outlet pipeline Tb5 from the side wall of the water washing tower 50 which is relatively lower than the inlet pipeline of the flue gas flow, and then selectively returned to the temporary retention tank A (or the temporary retention tank B) downward. Therefore, the red mud solid-liquid mixture 30 will circulate between the temporary retention tank A (or the temporary retention tank B) and the water washing tower 50, thereby continuously and fully eluting the flue gas flow continuously passing through the inside of the water washing tower 50.
[0042] Because the upper water washing tower 50 continuously performs the leaching action on the flue gas flow, the pH value of the liquid collected downward will slowly drop to 8.0-8.3. Therefore, when the temporary retention tank A (or the temporary retention tank B) in the circulation work detects that the pH value of the liquid drops to 8.0-8.3, the liquid discharge work of the temporary retention tank A (or the temporary retention tank B) is stopped, and at the same time, the temporary retention tank B (or the temporary retention tank A) is switched to pump the red mud solid-liquid mixture 30 into the water washing tower 50 through the liquid delivery pipeline Tb2 to fully rinse the flue gas flow in the water washing tower 50. Then, the liquid after absorbing carbon dioxide is also guided back to the temporary retention tank B (or the temporary retention tank A) through the liquid outlet pipeline Tb4. The circulation flow is stopped until the pH value of the liquid in the temporary retention tank B (or the temporary retention tank A) is detected to drop to 8.0-8.3. As for the temporary retention tank A (or the temporary retention tank B) that stopped working because the pH value of the liquid dropped to 8.0-8.3, the red mud solid-liquid mixture 30 (the pH value dropped to 8.0-8.3) was guided to a large collection tank C by a liquid outlet pipeline Tb6 for retention and waiting for subsequent treatment, thereby emptying the temporary retention tank A (or the temporary retention tank B). Then, new red mud solid-liquid mixture 30 (the pH value was between 9.4 and 10.7) was injected and waited for use.
[0043] After the flue gas flow is washed through the inside of the water washing tower 50, the carbon dioxide, sulfur dioxide, nitrogen oxides, and particulate pollutants contained therein are partially removed by the red mud solid-liquid mixture 30 (i.e., a carbon dioxide absorbent), so the proportion of carbon dioxide in the flue gas flow will decrease. Based on this, the water washing tower 50 can be set to be connected in series with one to four sections. When the water washing tower is set to be connected in series with four sections, the state is as follows: Figure 3 As shown, the first stage of the water washing tower 50 is Figure 2As shown, there are then a second-stage water washing tower 51, a third-stage water washing tower 52 and a fourth-stage water washing tower 53 in sequence. The configuration of each water washing tower 51, 52, 53 is the same as that of the first-stage water washing tower 50. Therefore, each water washing tower 50, 51, 52, 53 is respectively and individually equipped with a temporary retention tank A and a temporary retention tank B, and the liquid infusion pipeline Tb1 will be connected to pump the red mud solid-liquid mixture 30 into each temporary retention tank A and each temporary retention tank B for retention. Then, each water washing tower 50, 51, 52, 53 is respectively and individually equipped with a liquid infusion pipeline Tb2 to guide the red mud solid-liquid mixture 30 in the corresponding temporary retention tank A (or temporary retention tank B) to the corresponding water washing tower 50, 51, 52, 53 relative to the upper side wall to enter, so as to clean the corresponding water washing tower 50. , 51, 52, 53 are fully eluted inside, and the eluted liquids are collected downwards, and then each is led back to the corresponding temporary retention tank A (or temporary retention tank B) through a liquid outlet pipe Tb5, so the red mud solid-liquid mixed liquid 30 will form a circulation flow between each section of the water washing tower 50, 51, 52, 53 and the corresponding temporary retention tank A (or temporary retention tank B); at the same time, each section of the water washing tower 50, 51, 52, 53 is respectively provided with a liquid outlet pipe Tb6 below the temporary retention tank A and the temporary retention tank B corresponding to each section of the water washing tower 50, 51, 52, 53, so that when necessary, the red mud solid-liquid mixed liquid 30 (referring to the pH value (pH value) reduced to 8.0-8.3) can be selectively guided to the same large collection tank C for retention and waiting for subsequent treatment, so the large collection tank C can be shared by the same one.
[0044] As for the flow of flue gas, each section of the water washing tower 50, 51, 52, 53 has a side wall opposite to the lower side thereof, each of which is provided with an inlet pipe Tb3 for introducing the flue gas flow, and each section of the water washing tower 50, 51, 52, 53 has a top end thereof, each of which is provided with a gas delivery pipe Tb4 for guiding the flue gas flow out. However, in order to allow the flue gas flow to be continuously eluted through each section of the water washing tower 50, 51, 52, 53, the first section of the water washing tower 50, 51, 52, 53 is provided with a gas delivery pipe Tb4 for guiding the flue gas flow out. The gas delivery pipeline Tb4 of the water washing tower 50 is directly connected to the inlet pipeline Tb3 of the second section of the water washing tower 51, and the gas delivery pipeline Tb4 of the second section of the water washing tower 51 is directly connected to the inlet pipeline Tb3 of the third section of the water washing tower 52, and the gas delivery pipeline Tb4 of the third section of the water washing tower 52 is directly connected to the inlet pipeline Tb3 of the fourth section of the water washing tower 53; therefore, the flue gas flow is delivered from the inlet pipeline Tb3 of the first section of the water washing tower 50 to the inlet pipeline Tb3 of the first section of the water washing tower 50. Into, flows upward (and is rinsed) in the water washing tower 50 of the first section, and then is guided upward from the gas transmission pipeline Tb4 of the water washing tower 50 of the first section, and immediately enters the water washing tower 51 of the second section from the flow inlet pipeline Tb3 of the water washing tower 51 of the second section and flows upward (and is rinsed); in the same action, the flue gas flow is guided upward from the gas transmission pipeline Tb4 of the water washing tower 51 of the second section, and immediately enters the water washing tower 52 of the third section from the flow inlet pipeline Tb3 of the water washing tower 52 of the third section and flows upward (and is rinsed), and then is guided upward from the gas transmission pipeline Tb4 of the water washing tower 52 of the third section, and immediately enters the water washing tower 53 of the fourth section from the flow inlet pipeline Tb3 of the water washing tower 53 and flows upward (and is rinsed), and finally is guided upward from the gas transmission pipeline Tb4 of the water washing tower 53 of the fourth section and then proceeds with the subsequent procedures (may be directly discharged or subjected to other treatments).
[0045] It can be seen from the description that the red mud solid-liquid mixture 30 will continuously circulate between each section of the water washing tower 50, 51, 52, 53 and its corresponding temporary retention tank A (or the temporary retention tank B), and the flue gas flow is guided through each section of the water washing tower 50, 51, 52, 53 for multiple sections of continuous elution, so that the carbon dioxide content of the flue gas flow can be gradually reduced after passing through each section of the water washing tower 50, 51, 52, 53.
[0046] The above is the first treatment process for preparing a carbon dioxide absorbent using the red mud waste. As for the second treatment process for preparing a carbon dioxide absorbent using the red mud waste, please refer to Figure 4As shown, the process is similar to the first treatment process. First, a solid red mud waste 10 is selected as a material. The pH value of the solid red mud waste 10 is between 9.4 and 10.7. Then, the solid red mud waste 10 is mixed and washed with a water solution 20. If the mass of the water solution 20 is 100%, the mass of the solid red mud waste 10 is 1.0% to 10.0%. In the process of mixing and washing the solid red mud waste 10 and the water solution 20, the alkaline substances such as sodium, potassium, calcium, and magnesium contained in the red mud waste 10 are washed out and dissolved in the water solution 20.
[0047] The elutriation liquid at this time is the red mud solid-liquid mixed liquid 30 produced by the first treatment procedure, because sometimes even after sufficient elutriation, a few solid particles in the red mud cannot be completely dissolved into tiny powders. Even if the solid volume has been greatly reduced, it is still in a particle state, which will affect the absorption effect during the elution action. Therefore, a liquid pump 40a can be used to pump the red mud solid-liquid mixed liquid 30 through a filter device 60 to remove the solid particles. The filter device 60 is preferably 200-700 μm in pore size. The filtrate after passing through the filter device 60 is a red mud elutriation liquid 70 that is finer (only liquid and a few powders) than the red mud solid-liquid mixed liquid 30. Therefore, it can be seen that the second treatment procedure is mainly to add a step of filtering the red mud solid-liquid mixed liquid 30 to remove particles and obtain a fine red mud elutriation liquid 70 compared to the first treatment procedure.
[0048] Then, the red mud washing liquid 70 can be used as a carbon dioxide absorbent to wash the flue gas flow in the water washing tower 50. Figure 4 and Figure 2 As shown, and combined with reference Figure 4 and Figure 3 As shown, a pumping pump 80 is used to pump the red mud washing liquid 70 to the temporary retention tank A and the temporary retention tank B corresponding to the first to fourth water washing towers 50, 51, 52, 53 through the liquid delivery pipe Tb1 to wait for use. In other words, the red mud washing liquid 70 is allowed to continuously circulate between each water washing tower 50, 51, 52, 53 and its corresponding temporary retention tank A (or the temporary retention tank B) in exactly the same manner as the aforementioned operation process. At the same time, the flue gas flow is also guided to pass through each water washing tower 50, 51, 52, 53 for multiple stages of continuous washing. The only difference is that the aforementioned red mud solid-liquid mixture 30 is replaced by the red mud washing liquid 70. However, the effects are exactly the same, and the carbon dioxide content of the flue gas flow can also be reduced step by step after passing through each water washing tower 50, 51, 52, 53, and even the carbon dioxide content in the flue gas flow discharged from the last water washing tower 53 can reach an extremely low state.
[0049] The pH value (pH value) of the red mud solid-liquid mixture 30 or the red mud washing liquid 70 must be above 8.0-8.3 to be used as a carbon dioxide absorbent. Therefore, when using the red mud solid-liquid mixture 30 or the red mud washing liquid 70, "red mud seepage water" can also be added. This is because red mud waste is often stored in the open air, and its storage place is often exposed to wind, sun and rain. Therefore, "red mud seepage water" can be collected at the low place of the red mud open-air storage place, that is, the liquid that slowly flows to the lower place after the rain falls on the red mud. Because the "red mud seepage water" has flowed through the alkaline substances such as sodium, potassium, calcium, and magnesium contained in the red mud waste, the pH value (pH value) of the "red mud seepage water" is often between 9.5 and 12.0. Therefore, the "red mud seepage water" can be collected and mixed with the red mud solid-liquid mixture 30 or the red mud washing liquid 70 to be used together as a carbon dioxide absorbent.
[0050] The above-mentioned methods respectively use the red mud solid-liquid mixture 30 as a carbon dioxide absorbent or use the red mud elutriation liquid 70 as a carbon dioxide absorbent to elute the flue gas flow to absorb the carbon dioxide contained in the flue gas flow. According to the data obtained by the actual experiment of the present inventor, no matter whether the red mud solid-liquid mixture 30 is used as the carbon dioxide absorbent or the red mud elutriation liquid 70 is used as the carbon dioxide absorbent, the removal rate of the carbon dioxide contained in the flue gas flow by each water washing tower 50, 51, 52 or 53 is between 36% and 54%, with an average of 45% (n=7). Therefore, it can be obtained that:
[0051] 1. When the water washing towers 50 and 51 are connected in series in two stages, the removal rate of carbon dioxide contained in the flue gas flow by washing can reach an average of 70.0%;
[0052] 2. When the water washing towers 50, 51, and 52 are connected in series in three sections, the removal rate of carbon dioxide contained in the flue gas flow by elution can reach an average of 83.5%.
[0053] 3. When the water washing towers 50, 51, 52, and 53 are connected in series in four sections, the removal rate of carbon dioxide contained in the flue gas flow by washing can reach an average of 91.0%.
[0054] It can be seen that whether the red mud solid-liquid mixture 30 or the red mud washing liquid 70 is used as the carbon dioxide absorbent, after the action of eluting the flue gas flow, the absorption and removal of the carbon dioxide contained in the flue gas flow is indeed very effective.
[0055] The above is to use the solid red mud waste 10 mixed with the water liquid 20 to elute into a red mud solid-liquid mixture 30, or even further pass through a filtering step to become a red mud elutriated liquid 70, and then use the red mud solid-liquid mixture 30 or the red mud elutriated liquid 70 as a carbon dioxide absorbent, and transport it into the water washing tower 50 or simultaneously transport it into multiple sections of water washing towers 50, 51, 52, 53 to form a circulation flow, so as to fully rinse the rising flue gas flow to absorb the carbon dioxide in the flue gas flow. It has been confirmed by experiments that the red mud solid-liquid mixture 30 or the red mud elutriated liquid 70 is used as a carbon dioxide absorbent, and the absorption and removal of carbon dioxide contained in the flue gas flow can indeed have a good effect.
[0056] As for the further effect of using the red mud solid-liquid mixture 30 or the red mud elutriation liquid 70 as a carbon dioxide absorbent to absorb and remove the carbon dioxide contained in the flue gas flow, because the red mud solid-liquid mixture 30 or the red mud elutriation liquid 70 contains alkaline substances such as sodium, potassium, calcium, and magnesium, it will react to produce carbonates or bicarbonates after absorbing carbon dioxide, and then the carbonates or bicarbonates dissolved in the liquid are separated from toxic and harmful heavy metals, and the harmless carbonates or bicarbonates can be discharged into the ocean to become a carbon source for photosynthesis of aquatic plants in the ocean. In other words, the ocean is turned into a storage place (carbon sink) for carbon dioxide, which can be slowly released in the ocean to provide aquatic plants with the carbon source required for photosynthesis. In general, the research and development and application of the present invention have indeed made effective contributions to the effective reduction of the overall red mud waste on the earth and the net zero carbon emission earth-saving action.
Claims
1. A process for preparing a carbon dioxide absorbent using red mud waste, Features: A solid red mud waste is mixed with a water liquid for washing. The pH value of the solid red mud waste is between 9.4 and 10.
7. If the mass of the water liquid 20 is 100%, the mass of the solid red mud waste is 1.0% to 10.0%. During the washing process, alkaline substances such as sodium, potassium, calcium, and magnesium contained in the red mud waste are washed and dissolved in the water liquid to produce a red mud solid-liquid mixed liquid. The red mud solid-liquid mixed liquid serves as the carbon dioxide absorbent.
2. The process for preparing a carbon dioxide absorbent from red mud waste according to claim 1, Features: The red mud solid-liquid mixture is added with red mud seepage water having a pH value of more than 9.5 and mixed to be used as a carbon dioxide absorbent.
3. A process for preparing a carbon dioxide absorbent using red mud waste, Features: A solid red mud waste is mixed with a water liquid for elutriation. The pH value of the solid red mud waste is between 9.4 and 10.
7. If the mass of the water liquid 20 is 100%, the mass of the solid red mud waste is 1.0% to 10.0%. During the elutriation process, alkaline substances such as sodium, potassium, calcium, and magnesium contained in the red mud waste are elutriated and dissolved in the water liquid to produce a red mud solid-liquid mixed liquid. The red mud solid-liquid mixed liquid is pumped through a filter device to remove solid particles. After passing through the filter device, a red mud elutriation liquid is produced. The red mud elutriation liquid is used as the carbon dioxide absorbent.
4. The process for preparing a carbon dioxide absorbent from red mud waste according to claim 3, Features: The red mud washing liquid is mixed with red mud seepage water having a pH value of more than 9.5 and used as a carbon dioxide absorbent.
5. An application process for reducing carbon dioxide emissions using a carbon dioxide absorbent, Features: The carbon dioxide absorbent produced by claim 1, 2, 3 or 4 is introduced into a water scrubber to wash the flue gas flow rising through the water scrubber from top to bottom, thereby absorbing and removing the carbon dioxide content in the flue gas flow.
6. The process for reducing carbon dioxide emissions by using a carbon dioxide absorbent according to claim 5, Features: The gas-liquid volume ratio of the water scrubber is between 35 and 65, and the residence time of the flue gas flowing in the water scrubber is between 0.6 and 2.0 seconds.
7. The application process for reducing carbon dioxide emissions by using a carbon dioxide absorbent according to claim 5 or 6, Features: The carbon dioxide absorbent can be guided out of a temporary retention tank for retention before and after entering the water scrubber for leaching; the flue gas flow is in a guided state when passing upward after being leached through the inside of the water scrubber.
8. The process for reducing carbon dioxide emissions by using a carbon dioxide absorbent according to claim 5 or 6, Features: The water scrubber is configured to have one to four sections connected in series, and the flue gas flow after being eluted by the water scrubber of the previous section is guided into the water scrubber of the next section for rising. At the same time, the carbon dioxide absorbent is guided into the water scrubber of each section to elute the flue gas flow rising through the water scrubber from top to bottom to absorb and remove the carbon dioxide content in the flue gas flow.
9. The process for reducing carbon dioxide emissions by using a carbon dioxide absorbent according to claim 5 or 6, Features: The removal rate of carbon dioxide contained in the flue gas flow by the water scrubber in each section ranges from 36% to 54%, with an average of 45%.
10. The application process for reducing carbon dioxide emissions by using a carbon dioxide absorbent according to claim 5 or 6, Features: After the carbon dioxide contained in the flue gas flow is absorbed by the carbon dioxide absorbent, it will react to produce carbonates or bicarbonates. Therefore, after the carbonates or bicarbonates dissolved in the liquid are separated from the toxic and harmful heavy metals, the harmless carbonates or bicarbonates are discharged into the ocean and become a carbon source for photosynthesis of aquatic plants in the ocean.