CN113753985B - Method for preparing water treatment agent by utilizing red mud - Google Patents
Method for preparing water treatment agent by utilizing red mud Download PDFInfo
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Abstract
The invention provides a method for preparing a water treatment agent by utilizing red mud, which comprises the following steps of oxidizing the red mud to obtain oxidized mud; then dealkalizing the oxidized mud under the condition that the pH value is 5.0-6.8, and obtaining dealkalized red mud and filtrate after solid-liquid separation; adding magnesium-containing mineral powder into the dealkalized red mud for ore blending to obtain a base material; then, sequentially adding hydrochloric acid and sulfuric acid into the base material, and carrying out staged double-acidification to obtain a double-acidification material; and finally, drying, cooling and crushing to obtain the water treatment agent. The invention fully utilizes the useful components of iron, aluminum, silicon and the like in the red mud, and can effectively remove phosphorus, nitrogen and algae from eutrophic water body through the synergistic action of iron salt, aluminum salt, magnesium salt and silicon dioxide. The invention is a solid waste resource utilization method with short process, simple method and low investment.
Description
Technical Field
The invention relates to the technical field of resource utilization of solid wastes, in particular to a method for preparing a water treatment agent by utilizing red mud.
Background
The rapid development of economy is usually at the cost of high energy consumption and high resource consumption in industrial and agricultural production. The energy and resources that are not utilized in the production process are discharged into the environment in the form of sewage, waste gases and solid waste, causing pollution to the water, atmosphere and soil environment. The sedimentation of pollutants in the atmosphere and the surface runoff of rainfall flowing through farmlands and the ground can guide the pollutants into the water body finally, so that the water body becomes the final collection position of the pollutants in various forms.
Water is not only the foundation of human life, but also the foundation for the survival of natural living things. However, the pollution and eutrophication of offshore, rivers, lakes and reservoirs have become one of the major environmental problems in China nationwide. The occurrence of the water body pollution events is directly related to the pollution of the related water areas, in particular to the overhigh concentration of inorganic nutrient salts such as nitrogen, phosphorus and the like. Some water network rivers have total nitrogen as high as 10mg/L and total phosphorus in excess of 1mg/L. The eutrophication of the water body seriously influences the function and effective action of the water body, and causes huge economic and environmental losses. Therefore, many countries worldwide conduct a great deal of research and prevention and control work on the eutrophication problem of water bodies.
The red mud is polluting waste residue discharged when aluminum oxide is extracted in the aluminum industry, and generally 1.5 tons of red mud is generated for each 1 ton of aluminum oxide. The red mud produced in the world is about 7000 million tons, and the red mud produced in China is more than 3000 million tons every year. A large amount of red mud cannot be fully and effectively utilized, and can only be stacked by a large-area yard, so that a large amount of land is occupied, the environment is polluted, and the production and the life of human beings are influenced in many aspects, so that the yield and the harm of the red mud are reduced to the maximum extent, and the multi-channel and large-dosage resource utilization is realized.
For a long time, the comprehensive utilization of red mud is a world problem due to high alkali content and the like. The pH value of the red mud and the attached liquid thereof is 10.5-12.3, and the red mud and the attached liquid simultaneously contain renewable oxides or metal elements, thereby becoming the basis of the resource utilization of the red mud; various mineral particles in the red mud have the characteristics of good dispersibility, large specific surface area, good stability in solution and the like, and have wide application prospects in the field of environmental remediation.
Analysis and research show that: the red mud has complex mineral components, the main components of the red mud are calcium, aluminum, silicon, iron and the like, the main minerals are aragonite and calcite, the content of the aragonite and the calcite can reach 65%, and the red mud is opal, gibbsite, goethite and a small amount of titanium ore, siderite, water glass, sodium aluminate and caustic soda.
China always pays attention to the comprehensive utilization work of red mud, and develops the research work of comprehensive utilization technology in multiple disciplines and multiple fields. According to the physical properties, chemical components and mineral compositions of the red mud, the utilization method of the red mud is researched in a targeted manner, and the method is an effective way for realizing red mud reclamation.
In view of the above, there is a need to design an improved method for preparing water treatment agent by using red mud to solve the above problems.
Disclosure of Invention
In order to overcome the defects of the prior art, the invention aims to provide a method for preparing a water treatment agent by using red mud. The invention fully utilizes the useful components of iron, aluminum, silicon and the like in the red mud, and can perform the control functions of dephosphorization, denitrification and algae removal on the eutrophic water body through the synergistic effect of iron salt, aluminum salt, magnesium salt and silicon dioxide.
In order to realize the aim, the invention provides a method for preparing a water treatment agent by utilizing red mud, which comprises the following steps:
s1, preparing red mud slurry, and then adding an oxidant to oxidize the red mud to obtain oxidized mud slurry;
s2, dealkalizing the oxidized slurry obtained in the step S1 under the condition that the pH value is 5.0-6.8, and then carrying out solid-liquid separation to obtain dealkalized red mud and filtrate;
s3, adding magnesium-containing mineral powder into the dealkalized red mud obtained in the step S2 for ore blending to obtain a base material;
s4, sequentially adding hydrochloric acid and sulfuric acid into the base material obtained in the step S3, and carrying out double acidification by stages to obtain a double-acidification material; and then drying, cooling and crushing to obtain the water treatment agent.
As a further improvement of the invention, in step S1, the oxidizing mud comprises 100 parts by weight of water, 20-50 parts by weight of red mud and 0.1-2.5 parts by weight of oxidant; the oxidant is one or more of hydrogen peroxide, ozone, chlorine dioxide, perchlorate, chlorate or hypochlorite.
In a further improvement of the invention, in step S2, dilute hydrochloric acid with a mass concentration of 2-15% is used for dealkalization, and the dealkalization time is 1-5 h.
As a further improvement of the invention, in the step S3, the mass ratio of the dealkalized red mud to the magnesium-containing mineral powder is (2-10) to 1; the magnesium-containing mineral powder is a mineral containing magnesium oxide, magnesium chloride or magnesium carbonate or a processed product thereof.
As a further improvement of the invention, the magnesium-containing mineral powder is one or more of magnesite, dolomite, brucite, light-burned magnesite and calcined dolomite.
As a further improvement of the invention, in step S4, the addition amount of the hydrochloric acid is 10-40% of the weight of the base material, and the addition amount of the sulfuric acid is 10-40% of the weight of the base material; the mass concentration of the hydrochloric acid is 5-25%, and the mass concentration of the sulfuric acid is 95%.
As a further improvement of the invention, the mass concentration of the hydrochloric acid is 8-10%, and the addition amount is 20-40% of the weight of the base material.
As a further improvement of the present invention, the preparation method further comprises: adding a precipitation regenerant into the filtrate obtained in the step S2 to obtain dilute hydrochloric acid and a precipitate, wherein the precipitate comprises Mg (OH) 2 And CaSO 4 (ii) a The regenerated dilute hydrochloric acid is used for dealkalization in step S2, and Mg (OH) 2 For ore blending in step S3.
As a further improvement of the present invention, it is characterized in that, in step S4, the water treatment agent is used for in-situ or ex-situ treatment of a water body, and the application amount of the water treatment agent is 30g/m when the water treatment agent is used for water treatment 3 ～300g/m 3 。
As a further improvement of the invention, when the water treatment agent is used for ex-situ treatment of water, lime milk is adopted to adjust the pH value of sewage to 7.5-9.9, and then the water treatment agent is added.
The invention has the beneficial effects that:
1. the method for preparing the water treatment agent by using the red mud mainly comprises the steps of oxidation, dealkalization, ore blending, double-acidification and the like, and can prevent Fe in the dealkalization process through oxidation 2+ The leaching of (2) can also improve the purity of the gypsum in the regeneration step. The filtrate after dealkalization can be regenerated into hydrochloric acid and a magnesium-containing compound which are respectively used for dealkalization and ore blending steps, so that the resource utilization rate is high. Firstly, hydrochloric acid reacts with magnesium oxide and calcium oxide in the base material preferentially to generate chloride salt, so that calcium sulfate generated by directly using sulfuric acid can be prevented from blocking the reaction of the sulfuric acid with iron and aluminum; then sulfuric acid reacts with ferric oxide and aluminum oxide in the base material to generate sulfate, so that the use amount of the sulfuric acid can be reduced. Finally dryingBreaking, allowing the free silica to polymerize and promoting the mechanical activation of the silica. The invention fully utilizes the useful components of iron, aluminum, silicon and the like in the red mud, and can effectively remove phosphorus, nitrogen and algae from eutrophic water body through the synergistic action of iron salt, aluminum salt, magnesium salt and silicon dioxide.
2. The invention takes the solid waste red mud produced in the alumina industry as the basic raw material, has simple material selection, process and equipment, and is an applicable preparation method; by adopting the method, the cyclic resource utilization of each component in the red mud can be realized; the prepared algaecide can be directly sprayed on the water surface or the algaecide is added with water to be prepared into suspension liquid which is sprayed on the water surface to realize in-situ treatment; and the pH value of the sewage can be adjusted by lime milk and the like, and then the algaecide is added for ectopic treatment, so that the method is convenient and flexible.
Drawings
FIG. 1 is a flow chart of a method for preparing a water treatment agent by using red mud according to the invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in detail below with reference to specific embodiments.
It should be noted that, in order to avoid obscuring the present invention with unnecessary details, only the structures and/or processing steps closely related to the scheme of the present invention are shown in the specific embodiments, and other details not closely related to the present invention are omitted.
In addition, it is also to be noted that the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus.
Referring to fig. 1, the method for preparing a water treatment agent by using red mud provided by the invention is realized by the following technical scheme:
s1, oxidation: adding water into red mud and stirringStirring to obtain slurry with liquid-solid ratio of above 2, adding oxidant into the slurry, and adding Fe 2+ Oxidation to Fe 3+ And obtaining the oxidized slurry. The oxidant is one or more of hydrogen peroxide, ozone, chlorine dioxide, perchlorate, chlorate or hypochlorite, chlorite and the like. The addition amount of the oxidant is 0.2-5% of the mass of the red mud.
In the step, the Fe in the red mud is oxidized by an oxidant 2+ Oxidation to Fe 3+ Not only can prevent Fe in step S2 2+ The leaching of (2) can also improve the purity of the gypsum in the regeneration step.
S2, dealkalization: adding dilute hydrochloric acid into the oxidized slurry, adjusting the pH value of the slurry to 5.0-6.8, keeping the pH value for more than 1 hour, and carrying out solid-liquid separation to obtain dealkalized red mud and filtrate. The dilute hydrochloric acid is hydrochloric acid with the mass concentration of 2-15%, and the solid-liquid separation can be one of settling clarification, centrifugal filtration, vacuum filtration, pressure filtration and other methods.
In the step, the alkali in the red mud is neutralized by hydrochloric acid, so that the filtering performance of the red mud is improved, and the red mud can be reduced by more than 30%; to obtain a chlorine salt solution of calcium, magnesium, sodium, etc., and further, by-products such as gypsum, magnesium oxide, etc., can be obtained by the method in the regeneration step.
S3, ore blending: adding magnesium-containing mineral powder into the dealkalized red mud and uniformly stirring to obtain a base material. The adding amount of the magnesium-containing mineral powder is as follows in parts by weight: dealkalized red mud: magnesium-containing mineral powder = 2-10, preferably 100 parts of red mud and 20-40 parts of magnesium-containing mineral powder; the magnesium-containing mineral powder is any mineral or processed product thereof containing magnesium oxide, magnesium chloride or magnesium carbonate, such as one or more of magnesite, dolomite, brucite, light-burned magnesite, calcined dolomite and the like. The stirring method is not limited as long as the uniform mixing of the raw materials can be ensured.
In the step, magnesium-containing minerals are added into the dealkalized red mud, which is a raw material for providing magnesium salts for modification in the step S4, and the magnesium salts have phosphorus and nitrogen removal effects in the treatment of phosphorus and nitrogen-containing sewage.
S4, double acidification: under the condition of stirring, hydrochloric acid is added into the base material in batches, and then sulfuric acid is added into the base material in batches, so that the base material is modified into a double-acid-salt material. The batch adding mode can be selected, or the batch adding mode can be selected for more than 2 times; the hydrochloric acid is industrial hydrochloric acid with the concentration of 5-25%, and the preferred mass concentration is 8-10%; the sulfuric acid is 95% industrial sulfuric acid; the addition of the hydrochloric acid is 10 to 40 percent of the weight of the base material; the addition amount of the sulfuric acid is 10-40% of the weight of the base material. The use of concentrated hydrochloric acid is not recommended in the present invention in order to improve the working environment.
In the step, the activity of each component in the base material is utilized, hydrochloric acid is preferentially reacted with magnesium oxide and calcium oxide in the base material to generate chloride salt, so that calcium sulfate generated by directly using sulfuric acid is prevented from blocking the reaction of the sulfuric acid with iron and aluminum; then sulfuric acid reacts with iron oxide and aluminum oxide in the base material to generate sulfate, so that the use amount of the sulfuric acid can be reduced.
In the preparation practice, the adding amount of the hydrochloric acid is 75 to 100 percent of the theoretical amount of the reaction between the hydrochloric acid and the magnesium oxide in the base material; the addition amount of the sulfuric acid is determined according to the sulfuric acid and Fe in the base material 2 O 3 、Al 2 O 3 70-100% of the theoretical amount of the reaction is added.
The step is the technical core of the invention, namely, hydrochloric acid is selected to enable calcium oxide and calcium carbonate, magnesium oxide and magnesium carbonate in the base material to generate corresponding calcium chloride and magnesium chloride, so that calcium sulfate generated by directly using sulfuric acid is avoided. The newly generated calcium sulfate is colloid and may block the reaction of sulfuric acid with Fe and Al, so lowering the salinization effect.
S5, product formation: and (5) heating and drying the double-acid salt material obtained in the step (S4) to obtain a dry material, cooling, then crushing to-0.5 mm and 100%, and sealing and packaging to obtain the water treatment agent which is mainly used as an algaecide for a water body. The heating is to heat the double-acid salinization material to 50-200 ℃, preferably 150-200 ℃ by any heating mode, and dry for 1.0-1.5 h; drying is carried out on the basis that the moisture of the dry materials does not influence crushing; as the pulverization, any physical pulverization method can be used.
The step is not only the drying process of the double-acid salt compound, but also the polymerization process of the free silicon dioxide; the crushing is applied by using a medicament, and is also beneficial to the mechanical activation of silicon dioxide.
The heating temperature is limited within the range of 50-200 ℃, and the hydrolysis of the hydrated magnesium chloride during dehydration can be effectively prevented from generating magnesium oxide and hydrogen chloride gas, so that the product quality can be ensured, and the environmental pollution can be avoided.
S6, application: aiming at the eutrophic water body or the water body with the phenomena of water bloom, red tide, blue algae and the like, the algaecide obtained in the step S5 is scattered on the water surface or added with water to be prepared into suspension liquid which is sprayed on the water surface, so that the effects of removing phosphorus, nitrogen and algae can be achieved, and the in-situ treatment is realized. Under the condition of ectopic treatment, the pH of the sewage can be adjusted to 7.5-9.9 by lime milk, and the algaecide is added, so that the application effect of the algaecide can be better exerted. The amount of the algaecide is recommended to be 30g/m 3 ～300g/m 3 。
Preferably, S6 is specifically: under the condition of ectopic treatment, the pH of the sewage can be adjusted to 7.5-9.9 by lime milk, quicklime and the like, and the algaecide is added, so that the application effect of the algaecide can be better exerted. The dosage of the algaecide is 30g/m 3 ～200g/m 3 。
Obviously, the algaecide of the invention can be used for treating eutrophic water bodies and industrial wastewater and domestic sewage, and in order to facilitate the application of the algaecide, the invention does not claim the step and does not limit the application, usage and dosage of the algaecide.
Regeneration: adding a regenerant to the chloride salt solution obtained in step S2 to precipitate Mg (OH) respectively 2 And CaSO 4 And regenerating the solution into dilute hydrochloric acid. The regenerant comprises: sulfuric acid, lime milk or quicklime, etc. In the regeneration process, the addition amount of the regenerant is determined according to the concentration of calcium ions and magnesium ions in the solution. The regeneration process takes place as follows:
MgCl 2 +Ca(OH) 2 ＝Mg(OH) 2 ↓+CaCl 2
CaCl 2 +H 2 SO 4 ＝CaSO 4 ↓+2HCl
in the step, the regenerated dilute hydrochloric acid can be used for S2 dealkalization; precipitate outLai Mg (OH) 2 Can be directly used for ore blending in the step S3; precipitated CaSO 4 Can be used as building materials.
The preferred embodiments are:
s1, adding 100 parts of water, 30-40 parts of red mud and 1-2 parts of hydrogen peroxide as oxidants into a stirring tank in sequence, and uniformly stirring to obtain the oxidized slurry.
S2, while stirring and oxidizing the slurry, neutralizing alkali in the slurry by using dilute hydrochloric acid with the mass concentration of 8-10%, detecting the pH value at any time, keeping the pH value of the slurry within the range of 5.5-6.0 for 1.5 hours, performing sedimentation separation to obtain settled solids, namely dealkalized red mud, and obtaining supernatant for extracting magnesium hydride and calcium sulfate.
Example 1
Red mud produced by Guangxi division of Medium aluminum is selected, and the red mud is analyzed to be mainly Fe in component 2 O 3 、Al 2 O 3 CaO and SiO 2 And the like, as shown in Table 1.
TABLE 1 Main chemical composition (wt%) of red mud of the aluminum Guangxi division
| Fe 2 O 3 | Al 2 O 3 | SiO 2 | TiO 2 | CaO | MgO | Na 2 O |
| 36.6 | 18.8 | 8.5 | 6.8 | 17.6 | 1.1 | 3.6 |
The invention uses red mud to prepare water treatment agent (algaecide), and the preferred embodiment is as follows:
(1) And (3) sequentially adding 100 parts of water, 30 parts of red mud and 0.5 part of hydrogen peroxide into the stirring tank, and stirring for 5 minutes to obtain the oxidized slurry.
(2) While stirring and oxidizing the slurry, neutralizing alkali in the slurry by using dilute hydrochloric acid with the mass concentration of 8%, detecting the pH value at any time, keeping the pH value of the slurry within the range of 5.0-6.0 for 1.5 hours, settling and separating to obtain settled solids, namely dealkalized red mud, and obtaining supernatant for extracting magnesium hydride and calcium sulfate.
The dealkalized red mud was analyzed, and the main chemical components are shown in table 2.
TABLE 2 main chemical composition (wt%) of dealkalized red mud of Guangxi division of aluminum
| Fe 2 O 3 | Al 2 O 3 | SiO 2 | TiO 2 | CaO | MgO | Na 2 O |
| 50.1 | 24.8 | 12.1 | 9.2 | 2.5 | 0.2 | 0.3 |
(3) According to the dealkalized red mud: and (3) adding light-burned magnesite powder with the MgO content of 94.5wt% into the dealkalized red mud, and uniformly stirring to obtain the base material, wherein the weight part of the magnesium-containing mineral powder is = 5.
(4) Adding 8% dilute hydrochloric acid for 4 times while stirring the base material, wherein the addition amount of the hydrochloric acid is 25% of the weight of the base material; then adding 95% industrial concentrated sulfuric acid for 6 times, wherein the addition amount of the sulfuric acid is 40% of the weight of the base material, and modifying the base material into a double-acid acidized material.
(5) Heating the double-acid salt material to 170-190 ℃ in a rotary dryer by using combustion flue gas, and drying for 1.2-1.5 h; and after drying, grinding the dry materials by using a ball mill, and sealing and packaging to obtain the finished product algaecide A.
Example 2
The red mud in the example 1 is selected, and the red mud produced by the Guangxi branch company of Middling aluminum is still used for preparing the water treatment agent (algaecide), and the preferred specific implementation mode is as follows:
(1) 100 parts of water, 30 parts of red mud and 2 parts of calcium hypochlorite are sequentially added into a stirring tank, and stirred for 5 minutes to obtain oxidized slurry.
(2) While stirring and oxidizing the slurry, neutralizing alkali in the slurry by using dilute hydrochloric acid with the mass concentration of 8%, detecting the pH value at any time, keeping the pH value of the slurry within the range of 5.0-6.0 for 2.0 hours, settling and separating to obtain settled solids, namely dealkalized red mud, and obtaining supernatant for extracting magnesium hydride and calcium sulfate.
The dealkalized red mud is analyzed, and the main chemical components are shown in table 3:
TABLE 3 main chemical composition (wt%) of dealkalized red mud of Alguangxi division
| Fe 2 O 3 | Al 2 O 3 | SiO 2 | TiO 2 | CaO | MgO | Na 2 O |
| 50.0 | 24.8 | 12.3 | 9.5 | 2.1 | 0.2 | 0.1 |
(3) According to the dealkalized red mud: mgCl is added into dealkalized red mud according to the weight ratio of magnesium chloride hexahydrate =4 2 Magnesium chloride hexahydrate content of 43.2wt%And stirring uniformly to obtain the base material.
(4) Stirring the base material, and adding 8% dilute hydrochloric acid for 4 times, wherein the addition amount of the hydrochloric acid is 10% of the weight of the base material; adding 95% industrial concentrated sulfuric acid for 6 times, wherein the addition amount of the sulfuric acid is 50% of the weight of the base material, so that the base material is modified into a double-acid-salt material.
(5) Heating the double-acid salt material to 170-190 ℃ in a rotary dryer by using combustion flue gas, and drying for 1.4-1.6 h; and after drying, grinding the dry materials by using a ball mill, and sealing and packaging to obtain the finished product algaecide B.
Example 3
Selecting Bayer process red mud produced by Henan division of Medium-aluminum, analyzing the red mud to mainly contain Al 2 O 3 、SiO 2 、Fe 2 O 3 And CaO and the like, as shown in Table 4.
TABLE 4 Main chemical composition (wt%) of red mud from the Alhenan division
| Fe 2 O 3 | Al 2 O 3 | SiO 2 | TiO 2 | CaO | MgO | Na 2 O |
| 12.9 | 25.8 | 16.2 | 6.6 | 23.6 | 1.3 | 3.1 |
The invention uses red mud to prepare algaecide, and the preferred embodiment is as follows:
(1) 100 parts of water, 40 parts of red mud and 2 parts of calcium hypochlorite are sequentially added into a stirring tank, and stirring is carried out for 5 minutes to obtain oxidized slurry.
(2) While stirring and oxidizing the slurry, neutralizing alkali in the slurry by using dilute hydrochloric acid with the mass concentration of 8%, detecting the pH value at any time, keeping the pH value of the slurry within the range of 5.0-6.0 for 2.0 hours, settling and separating to obtain settled solids, namely dealkalized red mud, and obtaining supernatant for extracting magnesium hydride and calcium sulfate.
When the dealkalized red mud is analyzed, the main chemical components are shown in the table 5:
TABLE 5 main chemical composition (wt%) of dealkalized red mud of Alhenan division
| Fe 2 O 3 | Al 2 O 3 | SiO 2 | TiO 2 | CaO | MgO | Na 2 O |
| 19.5 | 38.4 | 24.6 | 9.9 | 3.1 | 0.3 | 0.1 |
(3) Dealkalized red mud in parts by weight: magnesium-containing mineral powder =4, calcined dolomite powder with the MgO content of 39.3wt% is added into the dealkalized red mud, and the mixture is uniformly stirred to obtain the base material.
(4) Adding 8% dilute hydrochloric acid for 4 times while stirring the base material, wherein the addition amount of the hydrochloric acid is 35% of the weight of the base material; adding 95% industrial concentrated sulfuric acid for 6 times, wherein the addition amount of the sulfuric acid is 30% of the weight of the base material, so that the base material is modified into a double-acid-salt material.
(5) Heating the double-acid salt material to 180-200 ℃ in a rotary dryer by using combustion flue gas, and drying for 1.5-1.8 h; and after drying, grinding the dry materials by using a ball mill, and sealing and packaging to obtain the finished product algaecide C.
In the application of the algaecide, the primary productivity of the water body is generally represented by the concentration of chlorophyll a (Chl-a), and the conclusion of the eutrophic lake steady-state conversion and ecosystem regulation and control principle (Zhongkou aquatic institute, zhongkou Wuhan plant institute and the like) is shown in the literature: "the limiting factors influencing the advantages of algae and submerged plants are TP concentration" and "the key link for regulating and controlling steady state conversion is to control TP concentration". In the following application examples, the invention is based on Total Phosphorus (TP), total Nitrogen (TN), transparency (Z) SD ) And chlorophyll a (Chl-a) as a parameter characterizing the effectiveness of the algaecide.
Application example A
The algaecide A prepared in example 1 was used to treat eutrophic water. The applied water body is lake water of a certain park, the water temperature is 30.8 ℃, the dominant algae species of the water body are blue algae, the suboptimal species are green algae, and the water body is green and is detected as eutrophic water. The comparison of the water quality at the respective dosages after 48h of the test with the direct application of algaecide A is shown in Table 6:
TABLE 6 comparison table of water quality indexes before and after treatment test (48 h)
Application example B
The algaecide B prepared in example 2 was used to treat eutrophic water. The water body used was the same as in application example a. With direct application of algaecide B, the respective water quality ratios after 48h of the test are shown in table 7:
TABLE 7 comparison table of water quality indexes before and after treatment test (48 h)
Application example C
The algaecide C prepared in example 3 was used to treat eutrophic water. The water body used was the same as in application example a. With direct application of algaecide C, the respective water quality ratios after 48h of the test are shown in table 8 below:
TABLE 8 comparison table of water quality indexes before and after treatment test (48 h)
Application example D
The eutrophic water body is treated and tested by adopting the algaecide A, B, C. The applied water body is lake water in the Dongting lake with the water temperature of 28.5 ℃, the dominant algae species of the water body are diatoms, and the suboptimal algae speciesIs green algae and blue algae, the water body is light green, and the water body is detected to be eutrophic water. When the algaecide is directly applied, 100g/m 3 Next, the water quality after 48h of the test is compared as shown in Table 9 below:
TABLE 9 water quality index comparison table before and after treatment test (48 h)
According to the test results of the application examples, the water treatment agent prepared by the invention can effectively remove Total Phosphorus (TP), total Nitrogen (TN) and chlorophyll a (Chl-a) in the water body, and has transparency (Z) SD ) The method is remarkably improved, and shows that the method for recycling the red mud is reasonable, low in recycling cost, high in resource utilization rate and convenient to put into practical application.
In conclusion, the method for preparing the water treatment agent by using the red mud provided by the invention fully utilizes the useful components such as iron, aluminum, silicon and the like in the red mud through the steps of oxidation, dealkalization, ore blending, double-acidification and the like, and can effectively perform the control functions of dephosphorization, denitrification and algae removal on the eutrophic water body through the synergistic effect of the iron salt, the aluminum salt, the magnesium salt and the silicon dioxide. The invention is a solid waste resource utilization method with short process, simple method and low investment, and the method can realize the effect of treating waste by waste.
Although the present invention has been described in detail with reference to the preferred embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the spirit and scope of the present invention.
Claims (10)
1. A method for preparing a water treatment agent by using red mud is characterized by comprising the following steps:
s1, preparing red mud slurry, and then adding an oxidant to oxidize the red mud to obtain oxidized mud slurry;
s2, dealkalizing the oxidized slurry obtained in the step S1 under the condition that the pH value is 5.0-6.8, and then carrying out solid-liquid separation to obtain dealkalized red mud and filtrate;
s3, adding magnesium-containing mineral powder into the dealkalized red mud obtained in the step S2 for ore blending to obtain a base material;
s4, sequentially adding hydrochloric acid and sulfuric acid into the base material obtained in the step S3, and carrying out double acidification by stages to obtain a double-acidification material; and then drying, cooling and crushing to obtain the water treatment agent.
2. The method for preparing a water treatment agent by using red mud according to claim 1, wherein in step S1, the oxidizing mud comprises 100 parts by weight of water, 20 to 50 parts by weight of red mud, 0.1 to 2.5 parts by weight of an oxidizing agent; the oxidant is one or more of hydrogen peroxide, ozone, chlorine dioxide, perchlorate, chlorate or hypochlorite.
3. The method for preparing a water treatment agent by using red mud according to claim 1, wherein in the step S2, dilute hydrochloric acid with the mass concentration of 2-15% is adopted for dealkalization, and the dealkalization time is 1-5 h.
4. The method for preparing the water treatment agent by using the red mud as claimed in claim 1, wherein in the step S3, the mass ratio of the dealkalized red mud to the magnesium-containing mineral powder is (2-10): 1; the magnesium-containing mineral powder is a mineral containing magnesium oxide, magnesium chloride or magnesium carbonate or a processed product thereof.
5. The method for preparing the water treatment agent by using the red mud as claimed in claim 4, wherein the magnesium-containing mineral powder is one or more of magnesite, dolomite, brucite, light-burned magnesite and calcined dolomite.
6. The method for preparing a water treatment agent by using red mud according to claim 1, wherein in step S4, the addition amount of the hydrochloric acid is 10-40% of the weight of the base material, and the addition amount of the sulfuric acid is 10-40% of the weight of the base material; the mass concentration of the hydrochloric acid is 5-25%, and the mass concentration of the sulfuric acid is 95%.
7. The method for preparing the water treatment agent by using the red mud as claimed in claim 6, wherein the mass concentration of the hydrochloric acid is 8-10%, and the addition amount is 20-40% of the weight of the base material.
8. The method for preparing a water treatment agent by using red mud according to claim 1, wherein the preparation method further comprises: adding a precipitation regenerant into the filtrate obtained in the step S2 to obtain dilute hydrochloric acid and a precipitate, wherein the precipitate comprises Mg (OH) 2 And CaSO 4 (ii) a The regenerated dilute hydrochloric acid is used for dealkalization in step S2, and Mg (OH) 2 For ore blending in step S3.
9. The method for preparing a water treatment agent using red mud according to any one of claims 1 to 8, wherein the water treatment agent is used as in-situ treatment or ex-situ treatment of a water body in an application amount of 30g/m for water treatment in step S4 3 ～300 g/m 3 。
10. The method for preparing a water treatment agent by using red mud according to claim 9, wherein when the water treatment agent is used for ex-situ treatment of a water body, the pH of the sewage is adjusted to 7.5 to 9.9 by using lime milk, and then the water treatment agent is added.
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