CN111362538B - Method for continuously dealkalizing red mud - Google Patents
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Abstract
The invention relates to the field of harmless treatment of industrial solid waste, in particular to a method for continuously dealkalizing red mud, which comprises the following steps: 1) pretreatment: preparing red mud and water into slurry, putting the slurry into a microwave reaction kettle, adding a mixed microbial powder/bagasse compound into the slurry, and mixing and stirring for 300-460 seconds under a microwave condition to obtain a pretreatment substance; 2) magnetic separation; 3) dealkalizing with calcium oxide; 4) dealkalizing oxalic acid; 5) separating liquid crystal; the method simultaneously realizes separation and recovery of elements such as silicon, iron, aluminum and the like, is beneficial to realizing resource comprehensive utilization of the red mud, has thorough dealkalization and low energy consumption, is green and ecological in the dealkalization process, and cannot generate secondary pollution.
Description
Technical Field
The invention relates to the field of harmless treatment of industrial solid wastes, in particular to a method for continuously dealkalizing red mud.
Background
The red mud is a large amount of industrial byproducts generated in the process of extracting aluminum oxide from bauxite by an alkaline process in aluminum production enterprises, is red strong-alkaline insoluble waste, and is basically made of Fe2O3，SiO2，Al2O3，Na2O, CaO and the like, generally account for 80 to 85 percent of the total chemical composition, and in addition, a small amount of MgO and TiO may be contained2、MnO、Cr2O3、SO3And a very small amount of rare elements, wherein the iron oxide content is high; the red mud is reddish red, has fine particles and difficult sedimentation, has a complex cemented frame pore structure, is mainly divided into three-stage structures of an aggregate, an aggregate and an aggregate, and various complicated gaps are formed among the three structures, so that the red mud has the advantages of fine particle size, strong water holding capacity (large water content), large specific surface area and high alkali content (taking Na as the raw material)2O, measured), the pH value is generally 10.0-12.5, and the waste liquid contains fluorine, iron and other impurity elements, so the waste liquid belongs to strong-alkaline harmful solid waste.
The harm of the red mud is reflected in that: 1) the alkaline liquor in the red mud permeates into the nature, so that the integral pH value of the surrounding water body is increased, and meanwhile, the toxicity of compounds in the water body is influenced by the pH value; 2) sodium, aluminum, fluoride and the like contained in the red mud enter underground water through various channels, the quality of a water body is also seriously polluted, harmful ions in various pollutants can be enriched in a human body after the polluted underground water is drunk for a long time, and irreparable harm is caused to the health of the human body, even the damage of an ecological system is caused; 3) because the natural specific gravity of the red mud particles is small, after the surface of the red mud is dried, a large amount of extremely fine red mud particles form flying dust in windy weather, and the flying dust falls into the air, thereby causing serious pollution to the surrounding environment and the atmosphere. The current research on comprehensive utilization of red mud mainly focuses on several aspects: (1) producing building materials such as cement, concrete and the like by using the red mud; (2) recovering valuable metals in the red mud; (3) developing a novel red mud material; (4) producing red mud microcrystalline glass, silicon fertilizer, ceramics and the like. However, the problem of efflorescence exists in the resource utilization process of the red mud, so that the dealkalization of the red mud is of great importance.
The dealkalization of the red mud is to reduce Na in the red mud2O、Na2CO3And the content of sodium-containing compounds can prolong the service life and improve the performance of red mud reuse and prevent secondary pollution. At present, the common methods for dealkalizing red mud are as follows: 1) acid leaching dealkalization: by utilizing the principle of acid-base neutralizationThe concentrated acid leaching method is used for realizing dealkalization of the red mud, acid reagents such as hydrochloric acid, sulfuric acid, phosphoric acid, nitric acid and the like are used as acid leaching agents, but secondary pollution can be caused when residue after the red mud is treated by the acid leaching method is treated, the method is poor in operation environment, high in requirement on acid resistance of equipment, high in equipment maintenance cost, large in waste liquid amount and difficult to treat; 2) lime water heating method: also known as Ca2+The displacement method comprises the steps that lime and red mud react at high temperature and high pressure to enable the lime and the red mud to generate lattice displacement reaction, Na + in the red mud tetrahedrite is replaced by Ca2+ to generate nepheline, and partial Na + in the red mud is transferred into solution, so that the alkali content of the red mud is reduced, but the reaction of reactants in the method needs 1-3 h to be heated to 300 ℃ in a reaction kettle, the energy consumption is high, and the sodium removal cost is high after the lime is added; 3) dealkalizing by a lime sintering method: the calcium oxide and the red mud are mixed and then are reacted in a pressure kettle at the temperature of 100-200 ℃ for sodium removal, but the energy consumption is larger. In addition, there are also dealkalization methods with various integrated technologies, and for example, the dealkalization of red mud disclosed in patent No. 200810231008.3 includes dilute sulfuric acid dealkalization stage and pressurized calcium oxide dealkalization, but there are problems that it is difficult to reduce the pH of red mud, a washing step is required, the amount of waste liquid to be treated is large, and it is difficult to reuse the waste liquid. Therefore, there is still a need to develop an efficient and ecological dealkalization method.
Disclosure of Invention
The invention provides a method for continuously dealkalizing red mud to solve the technical problems.
The method is realized by the following technical scheme:
a method for continuously dealkalizing red mud comprises the following steps:
1) pretreatment: taking the red mud and water according to the weight ratio of 1: (2-3) preparing slurry according to the mass ratio, putting the slurry into a microwave reaction kettle, adding 75-85 per mill of mixed microbial powder/bagasse compound into the slurry, and mixing and stirring for 300-460 seconds under the microwave condition to obtain a pretreatment substance;
2) magnetic separation: sequentially placing the pretreated substance under the conditions of the intensity of 1.4-1.8T and the intensity of 0.4-0.6T for magnetic separation to obtain the de-iron and de-silicon red mud, and separating iron elements and colloid components containing silicon dioxide;
3) calcium oxide dealkalization: adding calcium oxide into the de-ferrated and desilicated red mud, and controlling the calcium-sodium ratio to be (3-3.5): 1, uniformly mixing the materials, supplementing water until the liquid-solid ratio is (2.7-3.3):1, uniformly stirring, and reacting for 3-6h under the condition that the reaction temperature is controlled to be 20-99 ℃;
4) dealkalizing oxalic acid: adding oxalic acid accounting for 5-15% of the weight of the red mud into the calcium oxide dealkalized product, stirring for 20-60min, and carrying out solid-liquid separation to obtain solid matters, namely dealkalized red mud;
5) separation liquid crystal treatment: adding a dispersing agent with the mass of 1-5% into the separation liquid, heating for 500-.
The mass ratio of the mixed microbial powder to the bagasse in the mixed microbial powder/bagasse compound is 1: (94-99).
The mixed microbial powder is yeast powder and activated lactic acid bacteria powder, and the weight ratio of the yeast powder to the activated lactic acid bacteria powder is 1.1: (1.4-1.9) in terms of mass ratio.
The preparation method of the activated lactobacillus powder comprises the steps of inoculating the lactic acid bacteria which are frozen and stored into a liquid culture medium, carrying out activated culture at the temperature of 37 ℃, carrying out subculture for the second generation to obtain activated lactobacillus, carrying out centrifugal separation, washing collected bacterial sludge for 2-3 times by using sterilized normal saline, and freezing to prepare the lactic acid bacteria powder.
The lactic acid bacteria are lactobacillus amyloliquefaciens, bacillus coagulans and pediococcus acidilactici according to the weight ratio of 1: (8-11): (0.3-0.7) in mass ratio.
The culture medium consists of the following raw materials in parts by weight: 35-45g/L of unhydrolyzed macromolecular protein, 1-6g/L of honey, 6-9g/L of tryptone, 0.1-1.7g/L of diammonium citrate, 11-17g/L of anhydrous sodium acetate and MgSO4·7H2O 0.2-0.5g/L，MnSO4·4H20.1-0.2g/L of O, and water.
The preparation method of the mixed microbial bacteria powder/bagasse compound comprises the steps of placing the bagasse at 0-4 ℃ for standing for 20-30min, stirring the bagasse at the rotation speed of 100-300 rpm until the material temperature is 30-35 ℃, adding the mixed microbial bacteria powder, continuing stirring for 60-90s, stopping stirring, and naturally cooling until the material temperature is room temperature.
The microwave power in the step 1) is 100-180W.
The colloid component containing the silicon dioxide can be prepared into the bagasse porous carbon/silicon dioxide composite material with lithium storage performance after being processed, and is used for the field of lithium batteries.
Preferably, the reaction temperature in step 3) is 60-99 ℃.
The dosage of the oxalic acid accounts for 5-15% of the mass of the red mud.
The dispersing agent is polyethylene glycol.
The temperature of the microwave in the step 5) is 91-96 ℃.
The bagasse is cooled firstly and then mechanically stirred, so that the cell wall is damaged, the nutrient components required by acid production by lactic acid bacteria are provided, the granularity of the bagasse can be increased by adopting a mechanical stirring method, the activity of the effective components of the bagasse is improved, and an unstable compound can be formed by combining natural cooling, so that the separation of microbial powder and the bagasse compound is facilitated, and meanwhile, the phenolic hydroxyl structure in a large amount of lignin can be ensured. In addition, the compound prepared by the method has the characteristics of short preparation time and low energy consumption.
The invention utilizes the better synergistic effect of the lactobacillus amyloliquefaciens, the bacillus coagulans, the pediococcus acidilactici and the yeast, has higher acid production rate and acid production activity, and can produce various lactic acids, wherein the L-lactic acid is abundant.
The microwave is an electromagnetic wave with short wavelength and high frequency, which is a short name of a limited frequency band in radio waves, the frequency of the microwave is 300 MHz-300 GHz, namely the wavelength of the electromagnetic wave is 1 mm-1 m, and the microwave is a general name of millimeter waves, centimeter waves and decimetric waves; the microwave heating has penetrability, so that each point in the object can generate heat uniformly, the red mud is a weak wave absorption substance, the lignin wave absorption capacity is higher than that of the red mud, the excessive lignin can absorb the microwave and generate heat per se, the carbothermic reduction is generated, and the reduction of iron elements in the red mud to form magnetic Fe is facilitated3O4And elemental iron; simultaneously, the application selects low-power microwaves, the yeast is excited in a short time by the biological effect of the microwaves, the yeast can cooperate with the bacteria lactobacillus to avoid the influence of the microwaves to inhibit, and the lactobacillus is ensuredAcid molecules produced by lactic acid bacteria can interact with microwaves at the later stage of microwave treatment, so that acid liquor permeates into the red mud, and the aggregate and aggregate in the red mud can be damaged, so that a red mud cemented frame hole structure can be opened to form an ion channel, and ions can participate in replacement and dissolution; in addition, the bagasse contains lignin which is a high polymer consisting of three units with a phenylpropane structure, wherein phenolic hydroxyl groups in lignin molecules can be chelated with active metal ions on the surface of the red mud, and meanwhile, calcium dioxide in the red mud and the lignin molecules are connected to form hydrogen bonds, which is beneficial to destroying aggregate desilication in the red mud.
The method is favorable for removing iron and silicon dioxide in the red mud by utilizing magnetic separation, avoids the reduction of calcium oxide activity caused by the influence of multiple impurities in the calcium oxide dealkalization reaction, improves the concentration of a reaction system, and is further favorable for reducing the reaction temperature. The iron elements can be effectively separated by adopting the magnetic field intensity of 1.4-1.8T, the colloid components consisting of silicon dioxide and wood can be effectively separated by adopting the magnetic field intensity of 0.4-0.6T, because sodium-containing components in the red mud have no magnetism, and magnetic iron components can be separated by magnetic separation, the microwave is utilized in combination with a pretreatment stage, the microwave not only has thermal characteristics but also has electromagnetic characteristics, and the colloid components absorbing the microwave have microwave electromagnetic properties, and can be separated by a weak magnetic field.
The invention uses the dispersing agent to process the separating liquid, so that amorphous aluminum hydroxide is homogenized and dispersed in the separating liquid, and then microwave crystallization is used to quickly and efficiently form the slurry of aluminum hydroxide microcrystal with low viscosity, thereby improving the filtering effect.
Has the advantages that:
the dealkalization process realizes normal-pressure dealkalization, and when the dealkalization temperature is 60-99 ℃, the dealkalization efficiency is up to 95 percent, compared with the existing dealkalization process, the dealkalization temperature is reduced, the dealkalization time is shortened, and the energy consumption is saved.
The lime does not need to be washed after dealkalization, water consumption is saved, meanwhile, the oxalic acid belongs to organic acid, can be biodegraded, and has no pollution to the environment compared with the existing inorganic acid dealkalization process.
The method simultaneously realizes separation and recovery of elements such as silicon, iron, aluminum and the like, is beneficial to realizing resource comprehensive utilization of the red mud, has thorough dealkalization and low energy consumption, is green and ecological in the dealkalization process, and cannot generate secondary pollution.
Detailed Description
The following is a detailed description of the embodiments of the present invention, but the present invention is not limited to these embodiments, and any modifications or substitutions in the basic spirit of the embodiments are included in the scope of the present invention as claimed in the claims.
Example 1
A method for continuously dealkalizing red mud comprises the following steps:
1) pretreatment: taking the red mud and water according to the weight ratio of 1: 3, putting the prepared slurry into a microwave reaction kettle, adding 85 per mill of mixed microbial powder/bagasse compound into the slurry, and mixing and stirring for 460s under the microwave condition to obtain a pretreated substance;
2) magnetic separation: sequentially placing the pretreated substance under the conditions of the intensity of 1.8T and 0.6T for magnetic separation to obtain de-iron and de-silicon red mud, and separating iron elements and colloid components containing silicon dioxide;
3) calcium oxide dealkalization: adding calcium oxide into the de-iron desiliconized red mud, and controlling the calcium-sodium ratio to be 3.5: 1, uniformly mixing materials, supplementing water until the liquid-solid ratio is 3.3:1, uniformly stirring, and reacting for 6 hours under the condition that the reaction temperature is controlled to be 99 ℃;
4) dealkalizing oxalic acid: adding oxalic acid accounting for 15% of the mass of the red mud into the calcium oxide dealkalized product, stirring for 60min, and carrying out solid-liquid separation to obtain a solid matter, namely dealkalized red mud;
5) separation liquid crystal treatment: adding 5% of dispersant by mass into the separation liquid, heating under microwave condition for 800s, filtering, and drying the filtrate to obtain metal elements such as aluminum, sodium and the like;
the mass ratio of the mixed microbial powder to the bagasse in the mixed microbial powder/bagasse compound is 1: 99;
the mixed microbial powder is yeast powder and activated lactic acid bacteria powder, and the weight ratio of the yeast powder to the activated lactic acid bacteria powder is 1.1: 1.9 in mass ratio;
the preparation method of the activated lactobacillus powder comprises the steps of inoculating the lactic acid bacteria which are frozen and stored into a liquid culture medium, carrying out activated culture at the temperature of 37 ℃, carrying out subculture for the second generation to obtain activated lactobacillus, carrying out centrifugal separation, washing collected bacterial sludge for 2-3 times by using sterilized normal saline, and freezing to prepare the lactic acid bacteria powder;
the lactic acid bacteria are lactobacillus amyloliquefaciens, bacillus coagulans and pediococcus acidilactici according to the weight ratio of 1: 11: 0.7 in mass ratio;
the culture medium consists of the following raw materials in parts by weight: 45g/L of unhydrolyzed macromolecular protein, 6g/L of honey, 9g/L of tryptone, 1.7g/L of diammonium citrate, 17g/L of anhydrous sodium acetate and MgSO4·7H2O 0.5g/L，MnSO4·4H20.2g/L of O, and is prepared by water;
the preparation method of the mixed microbial powder/bagasse compound comprises the steps of placing bagasse at 4 ℃ for standing for 30min, stirring the bagasse at a rotating speed of 300 revolutions/min until the material temperature is 35 ℃, adding the mixed microbial powder, continuing stirring for 90s, stopping stirring, and naturally cooling until the material temperature is room temperature;
the microwave power in the step 1) is 180W;
the colloid component containing the silicon dioxide can be prepared into a bagasse porous carbon/silicon dioxide composite material with lithium storage performance after being processed, and is used for the field of lithium batteries;
the dispersing agent is polyethylene glycol;
the temperature of the microwave in the step 5) is 96 ℃.
Example 2
A method for continuously dealkalizing red mud comprises the following steps:
1) pretreatment: taking the red mud and water according to the weight ratio of 1: 2, putting the prepared slurry into a microwave reaction kettle, adding 75 per mill of mixed microbial powder/bagasse compound into the slurry, and mixing and stirring for 300 seconds under the microwave condition to obtain a pretreatment substance;
2) magnetic separation: sequentially placing the pretreated substance under the conditions of the intensity of 1.4T and the intensity of 0.4T for magnetic separation to obtain de-iron and de-silicon red mud, and separating iron elements and colloid components containing silicon dioxide;
3) calcium oxide dealkalization: adding calcium oxide into the de-ironed and desiliconized red mud, and controlling the calcium-sodium ratio to be 3:1, uniformly mixing, supplementing water until the liquid-solid ratio is 2.7:1, uniformly stirring, and reacting for 3 hours under the condition that the reaction temperature is controlled to be 20 ℃;
4) dealkalizing oxalic acid: adding oxalic acid accounting for 5% of the mass of the red mud into the calcium oxide dealkalized product, stirring for 20min, and carrying out solid-liquid separation to obtain a solid substance, namely dealkalized red mud;
5) separation liquid crystal treatment: adding a dispersing agent with the mass of 1% into the separation liquid, heating for 500s under the microwave condition, filtering, and drying the filtrate to obtain metal elements such as aluminum, sodium and the like;
the mass ratio of the mixed microbial powder to the bagasse in the mixed microbial powder/bagasse compound is 1: 94;
the mixed microbial powder is yeast powder and activated lactic acid bacteria powder, and the weight ratio of the yeast powder to the activated lactic acid bacteria powder is 1.1: 1.4 in mass ratio;
the preparation method of the activated lactobacillus powder comprises the steps of inoculating the lactic acid bacteria which are frozen and stored in a liquid culture medium, carrying out activated culture at the temperature of 37 ℃, carrying out subculture for the second generation to obtain activated lactobacillus, carrying out centrifugal separation, washing collected bacterial sludge for 2 times by using sterilized normal saline, and freezing to prepare the lactic acid bacteria powder;
the lactic acid bacteria are lactobacillus amyloliquefaciens, bacillus coagulans and pediococcus acidilactici according to the weight ratio of 1: 8: 0.3 of mass ratio;
the culture medium consists of the following raw materials in parts by weight: 35g/L unhydrolyzed macromolecular protein, 1g/L honey, 6g/L tryptone, 0.1g/L diammonium citrate, 11g/L anhydrous sodium acetate and MgSO4·7H2O 0.2g/L，MnSO4·4H20.1g/L of O, and is prepared by water;
the preparation method of the mixed microbial powder/bagasse compound comprises the steps of placing bagasse at 0 ℃ for standing for 20min, stirring the bagasse at a rotating speed of 100 revolutions per minute until the material temperature is 30 ℃, adding the mixed microbial powder, continuing stirring for 60s, stopping stirring, and naturally cooling until the material temperature is room temperature;
the microwave power in the step 1) is 100W;
the colloid component containing the silicon dioxide can be prepared into a bagasse porous carbon/silicon dioxide composite material with lithium storage performance after being processed, and is used for the field of lithium batteries;
the dispersing agent is polyethylene glycol;
the temperature of the microwave in the step 5) is 91 ℃.
Example 3
A method for continuously dealkalizing red mud comprises the following steps:
1) pretreatment: taking the red mud and water according to the weight ratio of 1: 2.5, putting the prepared slurry into a microwave reaction kettle, adding 80 per mill of mixed microbial powder/bagasse compound into the slurry, and mixing and stirring for 380 seconds under the microwave condition to obtain a pretreatment substance;
2) magnetic separation: sequentially placing the pretreated substance under the conditions of the intensity of 1.6T and 0.5T for magnetic separation to obtain de-iron and de-silicon red mud, and separating iron elements and colloid components containing silicon dioxide;
3) calcium oxide dealkalization: adding calcium oxide into the de-iron desiliconized red mud, and controlling the calcium-sodium ratio to be 3.2: 1, uniformly mixing, supplementing water until the liquid-solid ratio is 3:1, uniformly stirring, and reacting for 4.5 hours at the reaction temperature of 66 ℃;
4) dealkalizing oxalic acid: adding oxalic acid accounting for 10% of the mass of the red mud into the calcium oxide dealkalized product, stirring for 40min, and carrying out solid-liquid separation to obtain a solid matter, namely dealkalized red mud;
5) separation liquid crystal treatment: adding 3% dispersant by mass into the separated liquid, heating under microwave condition for 650s, filtering, and drying the filtrate to obtain metal elements such as aluminum, sodium, etc.;
the mass ratio of the mixed microbial powder to the bagasse in the mixed microbial powder/bagasse compound is 1: 97, a stabilizer;
the mixed microbial powder is yeast powder and activated lactic acid bacteria powder, and the weight ratio of the yeast powder to the activated lactic acid bacteria powder is 1.1: 1.7 in mass ratio;
the preparation method of the activated lactobacillus powder comprises the steps of inoculating the lactic acid bacteria which are frozen and stored in a liquid culture medium, carrying out activated culture at the temperature of 37 ℃, carrying out subculture for the second generation to obtain activated lactobacillus, carrying out centrifugal separation, washing collected bacterial sludge for 3 times by using sterilized normal saline, and freezing to prepare the lactic acid bacteria powder;
the lactic acid bacteria are lactobacillus amyloliquefaciens, bacillus coagulans and pediococcus acidilactici according to the weight ratio of 1: 9: 0.5 of mass ratio;
the culture medium consists of the following raw materials in parts by weight: 40g/L of unhydrolyzed macromolecular protein, 4g/L of honey, 7g/L of tryptone, 0.9g/L of diammonium citrate, 15g/L of anhydrous sodium acetate and MgSO4·7H2O 0.3g/L，MnSO4·4H20.15g/L of O, and is prepared by water;
the preparation method of the mixed microbial powder/bagasse compound comprises the steps of placing bagasse at 2 ℃ for standing for 25min, stirring the bagasse at a rotating speed of 200 revolutions per minute until the material temperature is 32 ℃, adding the mixed microbial powder, continuing stirring for 75s, stopping stirring, and naturally cooling until the material temperature is room temperature;
the microwave power in the step 1) is 150W;
the colloid component containing the silicon dioxide can be prepared into a bagasse porous carbon/silicon dioxide composite material with lithium storage performance after being processed, and is used for the field of lithium batteries;
the dispersing agent is polyethylene glycol;
the temperature of the microwave in the step 5) is 95 ℃.
Example 4
A method for continuously dealkalizing red mud comprises the following steps:
1) pretreatment: taking the red mud and water according to the weight ratio of 1: 3, putting the prepared slurry into a microwave reaction kettle, adding 75 per mill of mixed microbial powder/bagasse compound into the slurry, and mixing and stirring for 420 seconds under the microwave condition to obtain a pretreatment substance;
2) magnetic separation: sequentially placing the pretreated substance under the conditions of the intensity of 1.4T and 0.6T for magnetic separation to obtain de-iron and de-silicon red mud, and separating iron elements and colloid components containing silicon dioxide;
3) calcium oxide dealkalization: adding calcium oxide into the de-ironed and desiliconized red mud, and controlling the calcium-sodium ratio to be 3:1, uniformly mixing materials, supplementing water until the liquid-solid ratio is 3:1, uniformly stirring, and reacting for 6 hours at the reaction temperature of 54 ℃;
4) dealkalizing oxalic acid: adding oxalic acid accounting for 15% of the mass of the red mud into the calcium oxide dealkalized product, stirring for 20min, and carrying out solid-liquid separation to obtain a solid matter, namely dealkalized red mud;
5) separation liquid crystal treatment: adding a dispersing agent with the mass of 1% into the separation liquid, heating for 800s under the microwave condition, filtering, and drying the filtrate to obtain metal elements such as aluminum, sodium and the like;
the mass ratio of the mixed microbial powder to the bagasse in the mixed microbial powder/bagasse compound is 1: 94;
the mixed microbial powder is yeast powder and activated lactic acid bacteria powder, and the weight ratio of the yeast powder to the activated lactic acid bacteria powder is 1.1: 1.9 in mass ratio;
the preparation method of the activated lactobacillus powder comprises the steps of inoculating the lactic acid bacteria which are frozen and stored in a liquid culture medium, carrying out activated culture at the temperature of 37 ℃, carrying out subculture for the second generation to obtain activated lactobacillus, carrying out centrifugal separation, washing collected bacterial sludge for 2 times by using sterilized normal saline, and freezing to prepare the lactic acid bacteria powder;
the lactic acid bacteria are lactobacillus amyloliquefaciens, bacillus coagulans and pediococcus acidilactici according to the weight ratio of 1: 11: 0.3 of mass ratio;
the culture medium consists of the following raw materials in parts by weight: 45g/L of unhydrolyzed macromolecular protein, 6g/L of honey, 6g/L of tryptone, 0.1g/L of diammonium citrate, 17g/L of anhydrous sodium acetate and MgSO4·7H2O 0.2g/L，MnSO4·4H20.1g/L of O, and is prepared by water;
the preparation method of the mixed microbial powder/bagasse compound comprises the steps of placing bagasse at 3 ℃ for standing for 25min, stirring the bagasse at a rotating speed of 180 revolutions per minute until the material temperature is 32 ℃, adding the mixed microbial powder, continuing stirring for 60s, stopping stirring, and naturally cooling until the material temperature is room temperature;
the microwave power in the step 1) is 120W;
the colloid component containing the silicon dioxide can be prepared into a bagasse porous carbon/silicon dioxide composite material with lithium storage performance after being processed, and is used for the field of lithium batteries;
preferably, the reaction temperature in the step 3) is 75 ℃;
the using amount of the oxalic acid accounts for 8 percent of the mass of the red mud;
the dispersing agent is polyethylene glycol;
the temperature of the microwave in the step 5) is 94 ℃.
Example 5
A method for continuously dealkalizing red mud comprises the following steps:
1) pretreatment: taking the red mud and water according to the weight ratio of 1: 2.2, preparing slurry, putting the slurry into a microwave reaction kettle, adding 82 per mill of mixed microbial powder/bagasse compound into the slurry, and mixing and stirring for 360 seconds under the microwave condition to obtain a pretreatment substance;
2) magnetic separation: sequentially placing the pretreated substance under the conditions of the intensity of 1.5T and 0.4T for magnetic separation to obtain de-iron and de-silicon red mud, and separating iron elements and colloid components containing silicon dioxide;
3) calcium oxide dealkalization: adding calcium oxide into the de-iron desiliconized red mud, and controlling the calcium-sodium ratio to be 3.4: 1, uniformly mixing, supplementing water until the liquid-solid ratio is 3.3:1, uniformly stirring, and reacting for 4 hours at the reaction temperature of 90 ℃;
4) dealkalizing oxalic acid: adding oxalic acid accounting for 12% of the weight of the red mud into the calcium oxide dealkalized product, stirring for 30min, and carrying out solid-liquid separation to obtain a solid matter, namely dealkalized red mud;
5) separation liquid crystal treatment: adding a dispersing agent with the mass of 2% into the separation liquid, heating for 600s under the microwave condition, filtering, and drying the filtrate to obtain metal elements such as aluminum, sodium and the like;
the mass ratio of the mixed microbial powder to the bagasse in the mixed microbial powder/bagasse compound is 1: 95;
the mixed microbial powder is yeast powder and activated lactic acid bacteria powder, and the weight ratio of the yeast powder to the activated lactic acid bacteria powder is 1.1: 1.5 in mass ratio;
the preparation method of the activated lactobacillus powder comprises the steps of inoculating the lactic acid bacteria which are frozen and stored into a liquid culture medium, carrying out activated culture at the temperature of 37 ℃, carrying out subculture for the second generation to obtain activated lactobacillus, carrying out centrifugal separation, washing collected bacterial sludge for 2-3 times by using sterilized normal saline, and freezing to prepare the lactic acid bacteria powder;
the lactic acid bacteria are lactobacillus amyloliquefaciens, bacillus coagulans and pediococcus acidilactici according to the weight ratio of 1: 9: 0.5 of mass ratio;
the culture medium consists of the following raw materials in parts by weight: 37g/L unhydrolyzed macromolecular protein, 5g/L honey, 8g/L tryptone, 1g/L diammonium citrate, 13g/L anhydrous sodium acetate and MgSO4·7H2O 0.4g/L，MnSO4·4H20.2g/L of O, and is prepared by water;
the preparation method of the mixed microbial powder/bagasse compound comprises the steps of placing bagasse at 3 ℃ for standing for 25min, stirring the bagasse at a rotating speed of 200 revolutions per minute until the material temperature is 32 ℃, adding the mixed microbial powder, continuing stirring for 70s, stopping stirring, and naturally cooling until the material temperature is room temperature;
the microwave power in the step 1) is 150W;
the colloid component containing the silicon dioxide can be prepared into a bagasse porous carbon/silicon dioxide composite material with lithium storage performance after being processed, and is used for the field of lithium batteries;
preferably, the reaction temperature in the step 3) is 78 ℃;
the using amount of the oxalic acid is 7 percent of the mass of the red mud;
the dispersing agent is polyethylene glycol;
the temperature of the microwave in the step 5) is 93 ℃.
Comparative example 1
The difference from example 3 is that: the pretreatment of the step 1) and the magnetic separation treatment of the step 2) are not carried out.
Comparative example 2
The difference from example 3 is that: the magnetic separation treatment of the step 2) is not carried out.
Comparative example 3
The difference from example 3 is that: without pretreatment in step 1).
Comparative example 4
The difference from example 3 is that: comprises the steps of 1) pretreatment; 2) magnetic separation; 3) dealkalizing oxalic acid; 4) dealkalizing with calcium oxide; 5) and (5) separating liquid crystal.
Comparative example 5
The difference from example 3 is that: microwave is not used in the pretreatment of the step 1).
Experimental example 1
Taking bayer process red mud as an example, the comprehensive pH value of the red mud is 8.4, qualitative and quantitative analysis is performed on the element types and contents of the red mud by using an X-ray fluorescence spectrometer (XRF) technology, and the detection results are shown in table 1:
TABLE 1
Based on the XRF detection result, the content of the red mud in oxide forms of CaO, SiO2, Al2O3, Fe2O3, Na2O, MgO, TiO2 and the like is calculated, and is shown in Table 2:
table 2:
the red mud is divided into 10 groups, and after being treated in examples 1-5 and comparative examples 1-5, the element types and contents of the dealkalized red mud are qualitatively and quantitatively analyzed by adopting an X-ray fluorescence spectrometer (XRF) technology, and the dealkalization conditions are shown in Table 3:
TABLE 3
Experimental example 2
On the basis of experimental example 1, the following comparative experiments were set up for testing:
comparison 1: replacing the mixed microbial powder/bagasse compound with bagasse on the basis of the embodiment 1;
comparison 2: replacing the mixed microbial powder/bagasse compound with an activated lactic acid bacteria powder/bagasse compound on the basis of the embodiment 1;
comparison 3: replacing the mixed microbial powder/bagasse compound with a yeast/bagasse compound on the basis of the embodiment 1;
comparison 4: on the basis of the embodiment 2, replacing the mixed microbial powder/bagasse compound by an activated lactobacillus amyloliquefaciens/bagasse compound;
comparison No. 5: on the basis of the embodiment 2, replacing the mixed microbial powder/bagasse compound with an activated bacillus coagulans/bagasse compound;
comparison 6: replacing the mixed microbial powder/bagasse compound with an activated pediococcus acidilactici/bagasse compound on the basis of the embodiment 2;
comparison 7: replacing the mixed microbial powder/bagasse compound with a mixed microbial powder/lignin compound on the basis of the embodiment 4;
comparison No. 8: replacing the mixed microbial powder/bagasse compound with a mixed microbial powder/cellulose compound on the basis of the embodiment 4;
comparison 9: replacing the mixed microbial powder/bagasse compound with a mixed microbial powder/straw compound on the basis of the embodiment 4;
comparison 10: replacing the mixed microbial powder/bagasse compound with a mixed microbial powder/starch compound on the basis of the embodiment 5;
the types and contents of elements in the dealkalized red mud are qualitatively and quantitatively analyzed by adopting an X-ray fluorescence spectrometer (XRF) technology, and the dealkalization conditions are shown in a table 4:
TABLE 4
Experimental example 3
On the basis of experimental example 1, the following comparative experiments were set up for testing:
comparison 11: oxalic acid was replaced with citric acid on the basis of example 4;
comparison 12: oxalic acid was replaced with tartaric acid on the basis of example 4;
comparison 13: oxalic acid was replaced with hydrochloric acid on the basis of example 4;
comparison 14: oxalic acid was replaced with nitric acid on the basis of example 4;
comparison 15: replacing oxalic acid with bamboo vinegar on the basis of the embodiment 4;
the types and contents of elements in the dealkalized red mud are qualitatively and quantitatively analyzed by adopting an X-ray fluorescence spectrometer (XRF) technology, and the dealkalization conditions are shown in a table 5:
TABLE 5
Experimental example 4
On the basis of experimental example 1, the following comparative experiments were set up for testing:
the calcium oxide dealkalization temperatures were set to 20 ℃, 30 ℃, 40 ℃, 50 ℃, 60 ℃, 70 ℃, 80 ℃, 90 ℃, 100 ℃, 120 ℃, 130 ℃, 140 ℃, 150 ℃, 160 ℃, 170 ℃, 180 ℃, 190 ℃ and 200 ℃ respectively based on the example 3, and the results are shown in Table 6;
TABLE 6
Experimental example 5
The red mud of Bayer process in the experimental example 1 is taken and treated respectively in the examples 1-5 and the comparative examples 1-5 to prepare dealkalized red mud, and the dealkalized red mud, mineral powder, standard sand, water glass, desulfurized gypsum and admixture are prepared into baking-free bricks to be subjected to a blooming experiment; the preparation method of the baking-free brick comprises the following steps: putting the red mud, the mineral powder, the standard sand, the water glass, the desulfurized gypsum and the additive into a stirrer, and adding water to uniformly mix to obtain a mixture; weighing a proper amount of mixture, loading the mixture into a standard brick die, putting the standard brick die on an electronic universal tester, pressurizing to 20MPa at the loading speed of 1.0MPa/s and holding the load for 30s, unloading and demoulding at the same speed, covering the pressed green brick with a preservative film, putting the green brick into a drying box at 40 ℃, removing the preservative film after 3d, then putting the green brick on a sample frame, naturally curing for 28d, spraying water once a day, and curing for 30 d; m (modified red mud), m (mineral powder), m (standard sand), m (desulfurized gypsum), m (water glass), m (admixture), m (water), 55:22:23:2:3:2: 20; meanwhile, untreated Bayer process red mud is used as a control group;
TABLE 7 chemical compositions of mineral powder and desulfurized gypsum
Experiment of efflorescence
Taking 1 sample from each formula, putting the sample into a (105 +/-5) DEG C blast drying oven for drying for 24h, taking out the sample, cooling to room temperature, placing the surface with holes on the top surface of the sample upwards in a tray, injecting distilled water into the tray, exposing the sample outside, and recording the time; the time for soaking the sample in the tray is 24 days, water is often added in 2 days to keep the water level in the tray high, and then the sample is soaked in the water, wherein the test requires that the environmental temperature is 16-32 ℃ and the relative humidity is 35% -60%; after 24 days, the sample was taken out, left for 4 days under the same environmental conditions, and then dried in a forced air drying oven at (105. + -. 5 ℃ C.) to a constant temperature. The degree of blooming after drying was observed, and severe blooming occurred in the control group, while the cases of examples 1 to 5 and comparative examples 1 to 5 are shown in Table 8:
TABLE 8
Meanwhile, the compressive strength performance of the baking-free brick is tested by referring to a test method of JC/T422-2007 'non-sintered garbage tailing brick', the compressive strength of a control group is 18.1MPa, and the results of the cases of examples 1-5 and comparative examples 1-5 are shown in Table 9;
TABLE 9
Thus, it can be seen that: the bricks prepared from the dealkalized red mud have the advantages of insignificant blooming phenomenon and excellent compression resistance, and can be used for preparing building materials.
Experimental example 6
The method comprises the following steps of (1) preparing dealkalized red mud by treating Bayer process red mud in experimental example 1 in examples 1-5 and comparative examples 1-5 respectively; 100g of bentonite, 70g of peat and 50g of sawdust with the grain size of 0.3-0.45 mm are added into the red mud in turn, the mixture is uniformly mixed, and the red mud matrix is filled into a plastic flowerpot (20cm multiplied by 15cm) with 1000g per pot. And (3) sowing after the matrix is stable for 1 week, sowing 3 grass seeds in each pot, wherein each grass seed is 20, the sowing depth is about 2cm, and then covering soil and compacting. Watering is carried out immediately after sowing, the relative water content of the substrate in the depth of 10cm is ensured to be about 70 percent of the maximum field water capacity, and watering is carried out according to the dryness and the humidity of the substrate, so that the water requirement for the germination of grass seeds and the growth of plants is met. Calculating the germination rate after 7 d; wherein the bentonite has chemical purity, and cation exchange capacity of 0.98 × 10 measured by ammonium chloride-anhydrous ethanol method-3mol/100g, pH9.3. The organic matter content of the peat is 60 percent, and the humic acid content is 35 percent; the plant is ryegrass; meanwhile, untreated Bayer process red mud is used as a control group.
TABLE 10 Industrial and elemental analysis of sawdust
The statistical plant germination rates after 1 week of sowing are shown in table 11;
TABLE 11
Thus, it can be seen that: the dealkalized red mud prepared by the method can be used as a culture medium and has good germination promoting capacity for ryegrass.
Claims (8)
1. A method for continuously dealkalizing red mud is characterized by comprising the following steps:
1) pretreatment: taking the red mud and water according to the weight ratio of 1: 2-3, putting the prepared slurry into a microwave reaction kettle, adding 75-85 per mill of mixed microbial powder/bagasse compound into the slurry, and mixing and stirring for 300-460 seconds under the microwave condition to obtain a pretreatment substance;
2) magnetic separation: sequentially placing the pretreated substance under the conditions of the intensity of 1.4-1.8T and the intensity of 0.4-0.6T for magnetic separation to obtain the de-iron and de-silicon red mud, and separating iron elements and colloid components containing silicon dioxide;
3) calcium oxide dealkalization: adding calcium oxide into the de-ironed and desiliconized red mud, and controlling the calcium-sodium ratio to be 3-3.5: 1, after uniformly mixing, supplementing water until the liquid-solid ratio is 2.7-3.3:1, uniformly stirring, and reacting for 3-6h under the condition that the reaction temperature is controlled to be 20-99 ℃;
4) dealkalizing oxalic acid: adding oxalic acid accounting for 5-15% of the weight of the red mud into the calcium oxide dealkalized product, stirring for 20-60min, and carrying out solid-liquid separation to obtain solid matters, namely dealkalized red mud;
5) separation liquid crystal treatment: adding a dispersing agent with the mass of 1-5% into the separation liquid, heating under the microwave condition for 500-800s, filtering, and drying the filtrate to obtain aluminum and sodium metal elements;
the mixed microbial powder is yeast powder and activated lactic acid bacteria powder, and the weight ratio of the yeast powder to the activated lactic acid bacteria powder is 1.1: 1.4-1.9;
the lactic acid bacteria are lactobacillus amyloliquefaciens, bacillus coagulans and pediococcus acidilactici according to the weight ratio of 1: 8-11: 0.3-0.7 by mass ratio.
2. The method for continuously dealkalizing red mud according to claim 1, wherein the mass ratio of the mixed microbial powder to the bagasse in the mixed microbial powder/bagasse complex is 1: 94-99.
3. The method for continuously dealkalizing red mud according to claim 1 or 2, wherein the activated lactobacillus powder is prepared by inoculating the lactic acid bacteria preserved in a freezing way into a liquid culture medium, performing activated culture at the temperature of 37 ℃, performing subculture for the second generation to obtain the activated lactobacillus, performing centrifugal separation, washing the collected bacterial sludge with sterilized normal saline for 2-3 times, and freezing to prepare the lactic acid bacteria powder.
4. The method for continuously dealkalizing red mud according to claim 3, wherein the culture medium is composed of the following raw materials by weight: 35-45g/L of unhydrolyzed macromolecular protein, 1-6g/L of honey, 6-9g/L of tryptone, 0.1-1.7g/L of diammonium citrate, 11-17g/L of anhydrous sodium acetate and MgSO4∙7H2O 0.2-0.5g/L，MnSO4∙4H20.1-0.2g/L of O, and water.
5. The method for continuously dealkalizing red mud according to claim 1, wherein the preparation method of the mixed microbial powder/bagasse compound comprises the steps of placing the bagasse at 0-4 ℃ for standing for 20-30min, stirring the bagasse at a rotation speed of 100-300 rpm until the material temperature is 30-35 ℃, adding the mixed microbial powder, continuing stirring for 60-90s, stopping stirring, and naturally cooling until the material temperature is room temperature.
6. The method for continuously dealkalizing red mud according to claim 1, wherein the microwave power in the step 1) is 100-180W.
7. The method for continuously dealkalizing red mud according to claim 1, wherein the reaction temperature in the step 3) is 60-99 ℃.
8. The method for continuously dealkalizing red mud according to claim 1, wherein the temperature of the microwaves in the step 5) is 91-96 ℃.
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| CN113753985B (en) * | 2021-09-24 | 2023-01-20 | 南华大学 | Method for preparing water treatment agent by utilizing red mud |
| CN114408936A (en) * | 2022-02-26 | 2022-04-29 | 桂林理工大学 | Preparation method of sodium bentonite for metallurgical pellets based on red mud |
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