CN112624538A - Green and efficient red mud carbon dioxide carbonization dealkalization system and process - Google Patents
Green and efficient red mud carbon dioxide carbonization dealkalization system and process Download PDFInfo
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Abstract
The invention relates to a green and efficient red mud carbon dioxide carbonization dealkalization system and a process, wherein the dealkalization system comprises a red mud slurry stirring tank, a carbonization reactor, an iron remover, a dewatering screen, an ion separator and a water storage tank which are sequentially connected; the dealkalization process comprises the following steps: prepared red mud slurry and CO introduced from the bottom of the red mud slurry stirring tank2Carrying out pre-carbonization reaction; then feeding the mixture into a carbonization reactor to be filled with CO2Carbonizing and dealkalizing, and simultaneously performing ultrasonic action on the slurry; removing iron from the obtained slurry, and dehydrating/screening to obtain filtrate and dealkalized red mud product with low water content; and precipitating the filtrate, separating by an ion separator to obtain a concentrated solution containing high-concentration carbonate and a low-concentration circulating liquid, drying the concentrated solution to obtain carbonate, and reusing the low-concentration circulating liquid as circulating water. The invention realizes the continuous efficient red mud carbonization and dealkalization in the whole process, no harmful substances are generated in the reaction process, the dealkalized red mud is separated by grades,the carbonate product is efficiently recycled, and the water resource is recycled.
Description
Technical Field
The invention relates to the technical field of industrial waste disposal, in particular to a green and efficient red mud carbon dioxide carbonization dealkalization system and process.
Background
In the alumina industry, a large amount of industrial waste residues discharged after alumina is extracted from bauxite are red due to the fact that the industrial waste residues contain a large amount of iron oxide, and the industrial waste residues are called red mud. Typically, 0.6-2.0 tons of red mud are discharged per 1 ton of alumina produced. Bayer process, sintering process and combination process adopted in alumina industry are all required to be dissolved out in alkaline environment in the process of extracting alumina from bauxite, so that red mud is rich in a large amount of alkaline substances. Taking red mud produced by Bayer process as an example, the pH value is as high as more than 11. At present, no effective large-scale red mud utilization technology and scheme exist in the global scope. According to incomplete statistics of the global aluminum association, the global red mud yield exceeds 8 million tons in 2018. Most of these red mud piles are present in specially constructed red mud yards. Not only occupies a large amount of land, but also causes serious pollution to the local environment. The leaching of alkali and heavy metals can cause pollution to underground water and soil, and fine particles form dust under the action of wind power. In addition, a large amount of red mud accumulated in a yard may collapse under severe weather conditions, and the life and environmental safety of the area are threatened.
One key problem restricting the resource application of red mud is the high alkalinity of red mud. The alkaline substances in the red mud are divided into soluble alkali and insoluble alkali. Soluble alkali is easy to remove, but insoluble alkali can slowly release Na/K plasma into the solution, so that the red mud keeps high alkalinity for a long time. The high alkalinity of the red mud seriously limits the large-scale application of the red mud in the fields of building materials such as cement, ceramics and building bricks, and the fields of organic fillers, water purification, catalysis, soil recovery and the like. Researchers have conducted a lot of research on the dealkalization problem of red mud for a long time, and have also obtained certain technical achievements. At present, the red mud dealkalization technology mainly comprises the following steps: water alkali-eluting method, soda lime alkali-eluting method, waste acid neutralization method, carbonization alkali-eluting method, etc. However, these techniques have one or more problems of low efficiency, secondary pollution, poor production continuity, etc. Taking carbonization dealkalization as an example, CO in industrial tail gas is utilized2Carbonate is produced by carbonation reaction with alkaline substances in the red mud, the reaction time is long generally, and most of the existing process technologies are intermittent treatment and cannot be operated continuously. In addition, studies have shown that the pH of red mud returns to near its original pH after a period of time following single dealkalization by carbonization. Therefore, the research on the efficient green red mud dealkalization process applicable to industrial continuous production is an urgent problem to solve the red mud hazard and realize resource utilization.
Disclosure of Invention
Aiming at the defects of the existing red mud dealkalization technology, the invention provides a green and efficient red mud carbon dioxide carbonization dealkalization system and process, which realize continuous and harmless red mud dealkalization treatment and promote the solution of the red mud resource utilization problem.
The invention is realized in this way, a green and high-efficiency red mud carbon dioxide carbonization dealkalization system, which comprises a red mud slurry stirring tank, a carbonization reactor, an iron remover, a dewatering screen, an ion separator and a water storage tank;
the outlet at the bottom of the red mud slurry stirring tank is connected with the inlet of a carbonization reactor, the outlet of the carbonization reactor is connected with the inlet of an iron remover, the outlet of the iron remover is connected with the inlet of a dewatering screen, the filtrate outlet of the dewatering screen is connected with an ion separator, the concentrated solution outlet of the ion separator is connected with a dryer, the dilute solution outlet of the ion separator is connected with the inlet of a water storage tank, and the outlet of the water storage tank is connected with the water inlet of the red mud slurry stirring tank through a water pump;
the top of the red mud slurry stirring tank is provided with a red mud inlet, a reaction auxiliary agent inlet and a water inlet, the red mud slurry stirring tank is of an inverted cone structure and comprises a cylinder body located at the upper part and a cone body located at the lower part, the middle part of the cylinder body is provided with a stirrer, a porous air duct I communicated with a fan is arranged in the cone body in the circumferential direction, and the porous air duct I is used for providing CO required by the pre-carbonation dealkalization reaction for the slurry in the tank body2A gas;
a second porous air guide pipe communicated with the fan is arranged in the carbonization reactor along the whole bottom in the length direction, and the second porous air guide pipeFor supplying CO required for carbonation reaction into the carbonation reactor2A gas; two side surfaces of the carbonization reactor are provided with high-power ultrasonic generators at equal intervals to promote the dealkalization reaction process; the inlet to the outlet of the carbonization reactor are arranged from high to low in an inclined mode, and the angle alpha of inclination with the horizontal direction is more than 5 degrees and less than 25 degrees;
the ultrasound generated by the ultrasonic generator can lead CO introduced into the red mud slurry2The gas generates cavitation action, the gas is easier to react with alkaline substances in the red mud, and meanwhile, the ultrasonic action can destroy a carbonate coating layer formed on the surface of the red mud after the reaction is finished, so that the inhibition effect of the physical isolation of carbonate products on the core dealkalization reaction in the red mud particles is eliminated, and the dealkalization of the red mud is more complete; in addition, the ultrasonic treatment can destroy large particles formed by the agglomeration of the red mud particles, thereby being beneficial to subsequent screening.
The iron remover is used for recovering iron, cobalt, nickel and other ferromagnetic metal materials in the red mud slurry, and the recovered materials are produced as byproducts.
The dewatering screen is used for dewatering the dealkalized red mud slurry after iron removal, and separating dealkalized red mud products with low water content and filtrate.
The ion separator is used for carrying out concentration-dilution separation on the filtrate separated by the dewatering screen to separate out a concentrated solution containing high-concentration carbonate and a low-concentration circulating liquid.
Preferably, an alkali-resistant coating is coated inside the red mud slurry stirring tank body; the carbonization reactor is coated with an alkali-resistant coating inside and is wrapped with a sound absorption material layer outside.
Preferably, the iron remover is an electromagnetic iron remover or a permanent magnet iron remover.
Preferably, the dewatering screen is a high-frequency and double-layer structure screen, the mesh number of the upper layer screen is 80-150 meshes, the mesh number of the lower layer screen is 400-800 meshes, and the two screens can be exchanged according to the actual application requirements. The dealkalized red mud separated by the dewatering screen has the upper layer coarse particle screen residue which can be used as a water purifying agent, a chemical sewage adsorbent, a baking-free brick raw material and the like, and the lower layer fine particle dealkalized red mud which can be used as a raw material of cement, ceramics, an organic filler and the like.
Preferably, the filtrate outlet of the dewatering screen is connected with an ion separator through a sedimentation tank. The filtrate is precipitated by the precipitation tank and then subjected to ion separation, so that the separation efficiency is higher, and the purity of the recovered carbonate is higher.
A green and efficient red mud carbon dioxide carbonization dealkalization process comprises the following steps:
s1, red mud slurry preparation: crushing red mud, feeding the crushed red mud into a red mud slurry stirring tank at a constant speed, adding water according to a certain water-solid ratio, and stirring and mixing the water and the water by a stirrer to ensure that the red mud slurry fully stirred in the red mud slurry stirring tank and CO introduced from the bottom of the red mud slurry stirring tank2Pre-carbonization reaction is carried out to obtain slurry A.
S2, carbonization and dealkalization: the slurry A in the red mud slurry stirring tank enters a carbonization reactor through a bottom outlet, flows from a high position to a low position in the carbonization reactor under the action of gravity, and is introduced with CO at the bottom of the carbonization reactor2A carbonation reaction occurs; meanwhile, the slurry A is subjected to ultrasonic action through ultrasonic generators arranged on two sides of the carbonization reactor; and after the reaction is finished, discharging the slurry from an outlet at the bottom of the carbonization reactor to obtain dealkalized red mud slurry B.
S3, iron removal: and removing iron from the dealkalized red mud slurry B through an iron remover, and recovering magnetic metal materials such as iron, cobalt, nickel and the like in the dealkalized red mud slurry B to obtain dealkalized red mud slurry C after iron removal. The magnetic metal material recovered by the iron remover is output as a by-product.
S4, dewatering/screening: and (3) the dealkalized red mud slurry C after iron removal enters a dewatering screen for dewatering to obtain filtrate A and a dealkalized red mud product A with low water content.
S5, filtering the filtrate and circulating water: and after the filtrate A enters a sedimentation tank for sedimentation, separating by an ion separator to obtain a concentrated solution B containing high-concentration carbonate and a low-concentration circulating liquid C. And drying the concentrated solution B to obtain carbonate which is output as a byproduct. And the low-concentration circulating liquid C enters a water storage tank, is reused as circulating water and is pumped into the red mud slurry stirring tank by a water pump.
Preferably, in the step S1, the water-to-solid ratio of the red mud slurry is (0.1-10): 1.
Preferably, when red mud slurry is prepared, a reaction auxiliary agent for red mud carbonization and dealkalization can be added, and the reaction auxiliary agent is Ca (OH)2、CaO、MgO、CaCl2、MgCl2The mass ratio of the addition amount of the reaction auxiliary agent to the red mud solid is (0-0.1): 1.
Preferably, the red mud is derived from red mud slurry discharged in the alumina production process or a red mud disposal site; CO 22The gas is from chemical industry, building material, steel, electric power industry and other industries and contains high-concentration CO2Generally requires CO in the industrial tail gas2The concentration is more than 30%.
Preferably, the dealkalized red mud product a with low water content is classified and sieved by a double-layer structured dewatering sieve to obtain dealkalized red mud solids with different particle sizes, which are respectively: a large-sized dealkalized red mud product a1 and a small-sized dealkalized red mud product a 2.
The invention has the following advantages and beneficial effects:
1. the main process of red mud carbonization and dealkalization is transferred to the specially designed carbonization reactor with the ultrasonic assistance, the technological process is changed from the traditional long-time static reaction into a continuous flow dynamic process, and the continuous operation of the red mud carbonization and dealkalization process is realized; meanwhile, the introduction of ultrasonic action in the red mud carbonization process promotes the carbonization reaction process of alkali in the red mud and improves the dealkalization rate of the red mud; meanwhile, the ultrasonic action also plays a role in dispersing the red mud particles, thereby being beneficial to the screening and separation of the subsequent procedures.
2. The invention adopts CO in the industrial tail gas2The components are the red mud carbonization dealkalizing agent, and the reaction raw materials and the reaction products can not cause secondary pollution. The method consumes greenhouse gas CO through carbonization and dealkalization2Realizes the treatment of waste by waste. The process route simultaneously and obviously contributes to red mud disposal and carbon dioxide emission reduction by considering the existing red mud stacking amount.
3. The red mud CO of the invention2In the carbonization dealkalization process, materials naturally move from high to low under the action of gravity in the dealkalization reaction process, and special conveying equipment is not needed; the water can be recycled, and the actual water demand of the processIs small. The magnetic metal materials such as iron, cobalt, nickel and the like in the red mud can be recovered, the dealkalized red mud obtained by grading can be used as raw materials of various products, and the product carbonate obtained by carbonizing and dealkalizing the red mud can be output as a byproduct after drying. The invention can not only eliminate CO in the high-alkali red mud and the industrial tail gas2Has obvious environmental and social benefits and considerable economic benefits.
4. The invention realizes the continuous efficient red mud carbonization and dealkalization in the whole process. The dealkalized raw materials are easy to obtain, no harmful substances are generated in the reaction process, the dealkalized red mud is subjected to fractional separation, the dealkalized carbonate product is efficiently recycled, and the water resource is recycled.
5. The dealkalization process is carried out at normal temperature and normal pressure, does not need to add a heat source and a high-pressure device, and has low equipment requirement, simple operation and good safety.
Drawings
Fig. 1 is a process flow diagram of a red mud carbon dioxide carbonization dealkalization system provided by the embodiment of the invention.
In the figure: 1. a feeder; 2. a reaction auxiliary agent feeder; 3. a red mud slurry stirring tank; 31. a stirrer; 32. a porous first gas guide pipe; 4. a carbonization reactor; 41. a porous gas guide pipe II; 42. an ultrasonic generator; 5. a de-ironing separator; 6. dewatering screen; 7. a sedimentation tank; 8. an ion separator; 9. a water storage tank; 10. a fan; 11. a water pump; 12. and a dryer.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
In the description of the present invention, it is to be noted that, unless otherwise explicitly specified or limited, the terms "connected" and "connected" are to be interpreted broadly, e.g., as being fixed or detachable or integrally connected; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.
The embodiment of the invention provides a green and efficient red mud carbon dioxide carbonization dealkalization system, which comprises a red mud slurry stirring tank 3, a carbonization reactor 4, an iron remover 5, a dewatering screen 6, an ion separator 8 and a water storage tank 9; the bottom outlet of the red mud slurry stirring tank 3 is connected with the inlet of a carbonization reactor 4, the outlet of the carbonization reactor 4 is connected with the inlet of an iron remover 5, the outlet of the iron remover 5 is connected with the inlet of a dewatering screen 6, the filtrate outlet of the dewatering screen 6 is connected with an ion separator 8, the concentrated solution outlet of the ion separator 8 is connected with a dryer 12, the dilute solution outlet of the ion separator 8 is connected with the inlet of a water storage tank 9, and the outlet of the water storage tank 9 is connected with the water inlet of the red mud slurry stirring tank 3 through a water pump 11.
The top of the red mud slurry stirring tank 3 is provided with a red mud inlet, a reaction auxiliary agent inlet and a water inlet, and the interior of the red mud slurry stirring tank 3 is coated with an alkali-resistant coating; the red mud slurry stirring tank 3 is of an inverted cone structure and comprises a cylinder positioned on the upper part and a cone positioned on the lower part, wherein a stirrer 31 is arranged in the middle of the cylinder, a porous air guide pipe I32 communicated with a fan is arranged in the cone in the circumferential direction, and the porous air guide pipe I32 is used for providing CO required by the pre-carbonation dealkalization reaction for the slurry in the tank body2A gas.
A second porous gas guide pipe 41 communicated with the fan is arranged in the carbonization reactor 4 along the whole length direction of the bottom, and the second porous gas guide pipe 41 is used for providing CO required by the carbonation reaction into the carbonization reactor 42A gas; two side surfaces of the carbonization reactor 4 are provided with high-power ultrasonic generators 42 at equal intervals to promote the dealkalization reaction process; the inlet to the outlet of the carbonization reactor 4 is arranged from high to low in an inclined mode, and the angle alpha of inclination with the horizontal direction is more than 5 degrees and less than 25 degrees; the carbonization reactor 4 is coated with an alkali-resistant coating inside and is wrapped with a sound absorption material layer outside.
The ultrasound generated by the ultrasound generator 42 can lead CO introduced into the red mud slurry2Gas hairThe raw cavitation effect is easier to react with alkaline substances in the red mud, and the ultrasonic effect can destroy a carbonate coating layer formed on the surface of the red mud after the reaction is finished, so that the inhibition effect of the physical isolation of carbonate products on the core dealkalization reaction in the red mud particles is eliminated, and the dealkalization of the red mud is more complete; in addition, the ultrasonic treatment can destroy large particles formed by the agglomeration of the red mud particles, thereby being beneficial to subsequent screening.
The iron remover 5 is used for recovering iron, cobalt, nickel and other ferromagnetic metal materials in the red mud slurry, and the recovered materials are produced as byproducts. The iron remover 5 is an electromagnetic iron remover or a permanent magnet iron remover.
The dewatering screen 6 is used for dewatering the dealkalized red mud slurry after iron removal, and separating dealkalized red mud products with low water content and filtrate. The dewatering screen 6 is a high-frequency, double-layer structure screen, the mesh number of the upper layer screen is 80-150 meshes, the mesh number of the lower layer screen is 400-800 meshes, and the two screens can be exchanged according to the actual application requirements. The dealkalized red mud separated by the dewatering screen 6 has the upper coarse particle screen residue which can be used as a water purifying agent, a chemical sewage adsorbent, a baking-free brick raw material and the like, and the lower fine particle dealkalized red mud which can be used as a raw material of cement, ceramics, an organic filler and the like.
The ion separator 8 is used for carrying out concentration-dilution separation on the filtrate separated by the dewatering screen 6 to separate out a concentrated solution containing high-concentration carbonate and a low-concentration circulating liquid. The filtrate outlet of the dewatering screen 6 is connected with an ion separator 8 through a sedimentation tank 7. The filtrate is precipitated by the precipitation tank 7 and then subjected to ion separation, so that the separation efficiency is higher, and the purity of the recovered carbonate is higher.
A green and efficient red mud carbon dioxide carbonization dealkalization process comprises the following steps:
s1, red mud slurry preparation: crushing the red mud, feeding the crushed red mud into a red mud slurry stirring tank 3 at a constant speed, adding water according to a certain water-solid ratio, and stirring and mixing the mixture by a stirrer 31 to ensure that the red mud slurry fully stirred in the red mud slurry stirring tank 3 and CO introduced from the bottom of the red mud slurry stirring tank 32Pre-carbonization reaction is carried out to obtain slurry A.
S2, carbonization and dealkalization: slurry A in the red mud slurry stirring tank 3 passes throughThe bottom outlet enters a carbonization reactor 4, the slurry A flows from a high position to a low position in the carbonization reactor 4 under the action of gravity and is introduced with CO at the bottom of the carbonization reactor 42A carbonation reaction occurs; meanwhile, the slurry a is subjected to an ultrasonic action by ultrasonic generators 42 arranged on both sides of the carbonization reactor 4; and after the reaction is finished, discharging the slurry from an outlet at the bottom of the carbonization reactor 4 to obtain dealkalized red mud slurry B.
S3, iron removal: and removing iron from the dealkalized red mud slurry B by using an iron remover 5, and recovering magnetic metal materials such as iron, cobalt, nickel and the like in the dealkalized red mud slurry B to obtain dealkalized red mud slurry C after iron removal. The magnetic metal material recovered by the iron remover 5 is output as a by-product.
S4, dewatering/screening: and (3) feeding the dealkalized red mud slurry C subjected to iron removal into a high-frequency dewatering screen 6 for dewatering to obtain filtrate A and a dealkalized red mud product A with low water content. The dealkalized red mud product A with low water content is classified and sieved by a dewatering sieve 6 with a double-layer structure to obtain dealkalized red mud solids with different particle sizes, which are respectively: a large-sized dealkalized red mud product a1 and a small-sized dealkalized red mud product a 2.
S5, filtering the filtrate and circulating water: after the filtrate A enters a sedimentation tank 7 for sedimentation, a concentrated solution B containing high-concentration carbonate and low-concentration circulating liquid C are obtained after separation by an ion separator 8. And drying the concentrated solution B to obtain carbonate which is output as a byproduct. The low-concentration circulating liquid C enters a water storage tank 9 to be reused as circulating water and is pumped into the red mud slurry stirring tank 3 by a water pump 11.
Preferably, in the step S1, the water-solid ratio of the red mud slurry is (0.1-10): 1; the stirring speed of the stirrer 31 is 100-300 r/min.
Preferably, when red mud slurry is prepared, a reaction auxiliary agent for red mud carbonization and dealkalization can be added and fed into the red mud slurry stirring tank 3 by the reaction auxiliary agent feeder 2, wherein the reaction auxiliary agent is Ca (OH)2、CaO、MgO、CaCl2、MgCl2The mass ratio of the addition amount of the reaction auxiliary agent to the red mud solid is (0-0.1): 1.
Preferably, in the step S2, the power of the ultrasonic generator 42 is selected to be 400-800W.
Preferably, the red mud is derived from red mud slurry discharged in the alumina production process or a red mud disposal site; CO 22The gas is from chemical industry, building material, steel, electric power industry and other industries and contains high-concentration CO2Generally requires CO in the industrial tail gas2The concentration is more than 30%.
In conclusion, the invention realizes the continuous efficient red mud carbonization and dealkalization in the whole process. The dealkalized raw materials are easy to obtain, no harmful substances are generated in the reaction process, the dealkalized red mud is subjected to fractional separation, the dealkalized carbonate product is efficiently recycled, and the water resource is recycled. The whole dealkalization process is carried out at normal temperature and normal pressure, a heat source and a high-pressure device are not required to be added, the equipment requirement is low, the operation is simple, and the safety is good.
In order that the above-described embodiments of the invention may be better understood, further description thereof may be had with reference to specific examples.
Example 1
A green and efficient red mud carbon dioxide carbonization dealkalization process comprises the following steps:
s1, red mud slurry preparation: crushing red mud collected from a red mud yard, feeding the crushed red mud into a red mud slurry stirring tank 3 at a constant speed through a feeder 1, adding water according to a certain water-to-solid ratio, and stirring and mixing the mixture through a stirrer 31 to ensure that the red mud slurry fully stirred in the red mud slurry stirring tank 3 and CO introduced from the bottom of the red mud slurry stirring tank 32Pre-carbonization reaction is carried out to obtain slurry A.
S2, carbonization and dealkalization: the slurry A in the red mud slurry stirring tank 3 enters the carbonization reactor 4 through a bottom outlet, flows from a high position to a low position in the carbonization reactor 4 under the action of gravity, and is introduced with CO from the bottom of the carbonization reactor 42A carbonation reaction occurs; meanwhile, the slurry a is subjected to an ultrasonic action by ultrasonic generators 42 arranged on both sides of the carbonization reactor 4; so that the red mud slurry forms a 'cavitation' effect and the contact between gas and the red mud is increased. Meanwhile, the ultrasonic action peels off the carbonized product on the surface of the red mud, and the blocking effect of the carbonized product on the carbonization reaction is eliminated. And after the reaction is finished, discharging the slurry from an outlet at the bottom of the carbonization reactor 4 to obtain dealkalized red mud slurry B.
S3, iron removal: and removing iron from the dealkalized red mud slurry B by using an iron remover 5, and recovering magnetic metal materials such as iron, cobalt, nickel and the like in the dealkalized red mud slurry B to obtain dealkalized red mud slurry C after iron removal. The magnetic metal material recovered by the iron remover 5 is output as a by-product.
S4, dewatering/screening: and (3) feeding the dealkalized red mud slurry C subjected to iron removal into a high-frequency dewatering screen 6 for dewatering to obtain filtrate A and a dealkalized red mud product A with low water content. The dealkalized red mud product A with low water content is classified and sieved by a dewatering sieve 6 with a double-layer structure to obtain dealkalized red mud solids with different grain sizes, which are respectively: a large-sized dealkalized red mud product a1 and a small-sized dealkalized red mud product a 2. The dealkalized red mud product A1 can be used as a raw material of a sewage purifying agent, and the dealkalized red mud product A2 can be used as a substitute raw material for cement production.
S5, filtering the filtrate and circulating water: after the filtrate A enters a sedimentation tank 7 for sedimentation, a concentrated solution B containing high-concentration carbonate and low-concentration circulating liquid C are obtained after separation by an ion separator 8. The concentrated solution B is dried by a dryer 12 to obtain carbonate which is output as a byproduct. The low-concentration circulating liquid C enters a water storage tank 9 to be reused as circulating water and is pumped into the red mud slurry stirring tank 3 by a water pump 11.
In the embodiment 1, the mass ratio of the red mud and the water added in the step S1 is 1: 10; the stirring speed of the stirrer 31 is 150 r/min; CO 22Gas source selection of CO2Chemical industry waste gas with the concentration of more than 90 percent; the inclination angle of the carbonization reactor 4 in step S2 was 10 °; ultrasonic power 500W of the ultrasonic generator 42; in step S3, the iron remover 5 selects an electromagnetic iron remover; the mesh numbers of the two layers of the dewatering screen 6 in the step S4 are selected to be 80 mesh and 400 mesh, respectively.
Example 2
The difference from example 1 is that: the mass ratio of the red mud and the water added in the step S1 is 1:6, CaO is added as a reaction auxiliary agent for the carbonization and dealkalization of the red mud, and the mass ratio of the CaO to the red mud is 0.05: 1; the stirring speed of the stirrer 31 is 200 r/min; CO 22Gas source selection of CO2Cement industrial waste gas with concentration of more than 30%; the inclination angle of the carbonization reactor 4 in step S2 was 20 °; ultrasonic power 700W of the ultrasonic generator 42; step by stepIn step S3, the permanent magnet type iron remover 5 is selected as the iron remover 5; the mesh numbers of the two layers of the dewatering screen 6 in the step S4 are selected to be 100 mesh and 400 mesh, respectively. The dealkalized red mud product A1 is used as a raw material for preparing baking-free bricks, and the dealkalized red mud product A2 is used as an organic filler.
Finally, it should be noted that: the above examples are only intended to illustrate the technical solution of the present invention, but not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: it is to be understood that modifications may be made to the technical solutions described in the foregoing embodiments, or some or all of the technical features may be equivalently replaced, and the modifications or the replacements may not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the embodiments of the present invention.
Claims (10)
1. A green and efficient red mud carbon dioxide carbonization dealkalization system is characterized by comprising a red mud slurry stirring tank, a carbonization reactor, an iron remover, a dewatering screen, an ion separator and a water storage tank;
the outlet at the bottom of the red mud slurry stirring tank is connected with the inlet of a carbonization reactor, the outlet of the carbonization reactor is connected with the inlet of an iron remover, the outlet of the iron remover is connected with the inlet of a dewatering screen, the filtrate outlet of the dewatering screen is connected with an ion separator, the concentrated solution outlet of the ion separator is connected with a dryer, the dilute solution outlet of the ion separator is connected with the inlet of a water storage tank, and the outlet of the water storage tank is connected with the water inlet of the red mud slurry stirring tank through a water pump;
the top of the red mud slurry stirring tank is provided with a red mud inlet, a reaction auxiliary agent inlet and a water inlet; the red mud slurry stirring tank is of an inverted cone structure and comprises a cylinder positioned on the upper part and a cone positioned on the lower part, wherein a stirrer is arranged in the middle of the cylinder, a porous air duct I communicated with a fan is arranged in the cone in the circumferential direction, and the porous air duct I is used for providing CO required by the pre-carbonation dealkalization reaction for the slurry in the tank body2A gas;
a second porous air guide pipe communicated with the fan is arranged in the carbonization reactor along the whole bottom in the length directionThe second hole gas guide pipe is used for providing CO required by carbonation reaction in the carbonation reactor2A gas; two side surfaces of the carbonization reactor are provided with high-power ultrasonic generators at equal intervals; the inlet to the outlet of the carbonization reactor are arranged from high to low in an inclined mode, and the angle alpha of inclination with the horizontal direction is more than 5 degrees and less than 25 degrees;
the iron remover is used for recovering iron, cobalt, nickel and other ferromagnetic metal materials in the red mud slurry, and the recovered materials are produced as byproducts;
the dewatering screen is used for dewatering the dealkalized red mud slurry after iron removal, and separating dealkalized red mud product with low water content and filtrate;
the ion separator is used for carrying out concentration-dilution separation on the filtrate separated by the dewatering screen to separate out a concentrated solution containing high-concentration carbonate and a low-concentration circulating liquid.
2. The green and efficient carbon dioxide red mud dealkalization system of claim 1, wherein the red mud slurry stirring tank body is coated with an alkali-resistant coating inside; the carbonization reactor is coated with an alkali-resistant coating inside and is wrapped with a sound absorption material layer outside.
3. The green and efficient carbon dioxide red mud dealkalization system of claim 1, wherein the iron remover is an electromagnetic iron remover or a permanent magnet iron remover.
4. The green and efficient carbon dioxide carbonization and dealkalization system for red mud as claimed in claim 1, wherein the dewatering screen is a high-frequency and double-layer structure screen, the mesh number of the upper layer screen is 80-150 meshes, and the mesh number of the lower layer screen is 400-800 meshes.
5. The green and efficient carbon dioxide carbonizing and dealkalizing system for red mud of claim 1, wherein the filtrate outlet of the dewatering screen is connected with an ion separator through a sedimentation tank.
6. A green and efficient red mud carbon dioxide carbonization dealkalization process is characterized by comprising the following steps:
s1, red mud slurry preparation: crushing red mud, feeding the crushed red mud into a red mud slurry stirring tank at a constant speed, adding water according to a certain water-solid ratio, and stirring and mixing the water and the water by a stirrer to ensure that the red mud slurry fully stirred in the red mud slurry stirring tank and CO introduced from the bottom of the red mud slurry stirring tank2Carrying out pre-carbonization reaction to obtain slurry A;
s2, carbonization and dealkalization: the slurry A in the red mud slurry stirring tank enters a carbonization reactor through a bottom outlet, flows from a high position to a low position in the carbonization reactor under the action of gravity, and is introduced with CO at the bottom of the carbonization reactor2A carbonation reaction occurs; meanwhile, the slurry A is subjected to ultrasonic action through ultrasonic generators arranged on two sides of the carbonization reactor; after the reaction is finished, discharging the slurry from an outlet at the bottom of the carbonization reactor to obtain dealkalized red mud slurry B;
s3, iron removal: removing iron from the dealkalized red mud slurry B through an iron remover, and recovering magnetic metal materials such as iron, cobalt, nickel and the like in the dealkalized red mud slurry B to obtain dealkalized red mud slurry C after iron removal;
s4, dewatering/screening: the dealkalized red mud slurry C after iron removal enters a dewatering screen for dewatering to obtain filtrate A and a dealkalized red mud product A with low water content;
s5, filtering the filtrate and circulating water: after the filtrate A enters a sedimentation tank for sedimentation, separating by an ion separator to obtain a concentrated solution B containing high-concentration carbonate and a low-concentration circulating liquid C; and drying the concentrated solution B to obtain carbonate which is output as a byproduct, and delivering the low-concentration circulating liquid C into a water storage tank to be reused as circulating water and pumped into a red mud slurry stirring tank by a water pump.
7. The green and efficient carbon dioxide carbonization dealkalization process for red mud according to claim 6, wherein in the step S1, the water-solid ratio of the red mud slurry is (0.1-10): 1.
8. The green and efficient carbon dioxide carbonization dealkalization process of red mud according to claim 6, characterized in that in the step S1, red mud slurry is preparedDuring the material preparation, a reaction auxiliary agent for red mud carbonization and dealkalization can be added, wherein the reaction auxiliary agent is Ca (OH)2、CaO、MgO、CaCl2、MgCl2The mass ratio of the addition amount of the reaction auxiliary agent to the red mud solid is (0-0.1): 1.
9. The green and efficient carbon dioxide carbonization dealkalization process for red mud according to claim 6, characterized in that the red mud is derived from red mud slurry discharged from alumina production process or red mud disposal site; CO 22The gas is from chemical industry, building material, steel, electric power industry and other industries and contains high-concentration CO2Industrial exhaust gas, CO in industrial exhaust gas2The concentration is more than 30%.
10. The green and efficient carbon dioxide carbonization and dealkalization process for red mud according to claim 6, wherein the dealkalized red mud product A with low water content is classified and sieved by a dewatering sieve with a double-layer structure to obtain dealkalized red mud solids with different particle sizes, which are respectively: a large-sized dealkalized red mud product A1 and a small-sized dealkalized red mud product A2; the dealkalized red mud product A1 can be used as a water purifying agent, a chemical sewage adsorbent, a baking-free brick raw material and the like, and the dealkalized red mud product A2 can be used as a raw material of cement, ceramics, organic fillers and the like.
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