CN1247461C - Method for preparing oxide of bimetal and hydrotalcite by using Bayer red mud as raw material - Google Patents
Method for preparing oxide of bimetal and hydrotalcite by using Bayer red mud as raw material Download PDFInfo
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- CN1247461C CN1247461C CN 200410067225 CN200410067225A CN1247461C CN 1247461 C CN1247461 C CN 1247461C CN 200410067225 CN200410067225 CN 200410067225 CN 200410067225 A CN200410067225 A CN 200410067225A CN 1247461 C CN1247461 C CN 1247461C
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Abstract
The present invention discloses a method for preparing bimetal oxide and hydrotalcite from bajer red mud as raw material, which comprises the following steps: mixing the oxide and hydroxide of bivalent metal and red mud; treating the mixture with pulping, drying and calcination to prepare bimetal oxide; hydrating the bimetal oxide in a carbonate or hydrocarbonate solution to prepare hydrotalcite. The method has the advantages of simple technological process and little equipment investment, and adopts industrial waste as raw material so as to greatly reduce the cost and consumption and simultaneously solve the problems of the placement and environmental damage of large amounts of red mud. The bimetal oxide and hydrotalcite as the prepared products can be used as catalysts and catalyst carriers in the field of chemistry and chemical industry, the material for infrared absorption, ultraviolet absorption and barriers in the field of functional material and the flame retardant agents and PVC stabilizing agents in the field of plastic industry. The bimetal oxide and hydrotalcite as the prepared products have strong adsorption effect on many poisonous and harmful negative ions in the field of environment protection, and thus, the prepared products can be used for sewage processing, pollution prevention and environment restoration.
Description
Technical Field
The invention relates to a method for preparing bimetallic oxide and hydrotalcite by taking industrial waste red mud formed in the production process of alumina by a Bayer process as a raw material.
Background
The red mud is the waste with the largest quantity in the production process of the alumina and is also the largest pollution source. About 0.5-2.0 tons of red mud is formed per ton of alumina produced. At present, wet dam building and red mud piling are adopted in alumina plants, and alkali liquor contained in the red mud is easy to leak, so that underground water is polluted and soil salinization is caused. If the red mud is stacked after being dried and dehydrated, a large amount of energy is consumed, and the land is still occupied. The environmental hazard caused by the piling up of the red mud has attracted social attention.
There are three methods for producing alumina in the world today, the bayer process, the sintering process and the combined process. The Bayer process proposed by Karl Bayer (1887) is suitable for the treatment of high alumina, high iron, bauxite of the boehmite type and the gibbsite type. The method uses NaOH to selectively dissolve Al in ore2O3And precipitating pure Al (OH) from the solution3And then calcined to obtain the alumina. Oxidation in discharged red mudHigh Al, Fe oxide and alkali contents, high pH value up to 13.2, and high corrosion. The sintering method and the combined method are suitable for processing high-aluminum, high-silicon and low-iron diaspore type, kaolinite type and nepheline type bauxite to produce red mud CaO, SiO2High content, low content of alumina and iron oxide. The method provided by the invention is suitable for treating Bayer process red mud, and the chemical composition of the method is shown in reference document [1]]。
According to the characteristic of high iron content of the Bayer red mud, some mineral companies propose a development scheme of taking the Bayer red mud as an iron-making raw material, namely: drying and dehydrating the Bayer red mud, roasting in a reducing atmosphere to convert iron oxide into magnetite, and magnetically separating to prepare the metallurgical agglomerate. The product obtained by the method has low added value, is difficult to compete with the existing iron ore, and is not put into use due to economic factors. Attempts have also been made to use bayer red mud as a covering layer and absorbent for landfill, and to use red mud for the development of artificial soil, both of which have the main purpose of solving the problem of stacking a large amount of red mud and the problem of environment, rather than developing a secondary product. The current situation of comprehensive utilization of red mud is described in the references [1-5].
Since the main constituents of bayer red mud are hydroxides of Al and fe (iii), it is theoretically possible to use them as raw materials for the preparation of bimetallic oxides and hydrotalcites.
Hydrotalcite is also known as Layered Double Hydroxides, abbreviated as LDH. It has a layered structure, structured layers consisting of hydroxides of divalent and trivalent metals, filled with carbonate or other anions between the structured layers, and is therefore also referred to as anionic clay. Hydrotalcite is converted into a Double metal oxide, abbreviated as LDO, after dehydration by heating and loss of hydroxyl groups. It partially retains the original layered structure, and can recover and rebuild the crystal structure of hydrotalcite by absorbing water molecules, anions and hydroxide radicals in aqueous solution.
LDH and LDO are artificial synthetic layered mineral materials which are popular in recent years and can be used as catalysts and catalyst carriers in the fields of chemistry and chemical engineering; in the field of functional materials, as infrared and ultraviolet absorbing and blocking materials; in the plastic industry, can be used as a flame retardant and a PVC stabilizer; in the field of environmental protection, the compounds have strong adsorption effect on a plurality of toxic and harmful anions, so the compounds have wide application prospect in the aspects of sewage treatment, pollution prevention, environmental remediation and the like.
Reference to the literature
[1]Yangshuang, Caozaihua, the current situation of comprehensive utilization and development of red mud produced by alumina. Mineral protection and utilization, 1999 (6): 46-49.
[2]Ginger is delightful and peaceful, and the current situation of comprehensive utilization of red mud in an alumina plant is provided. Environmental science and technology, 2003, 26 (1): 40-42.
[3]And (4) comprehensive utilization of the wintersweet, the Maolanan and the red mud. Non-ferrous metals industry, 2002 (5): 57-58.
[4]Plum autumn, utilization and development of aluminum industrial waste residues. Light metals, 1995(1), 26-27.
[5]Nevin Yalcin，Vahdettin Sevinc，Utilization of bauxite waste in ceramicglazes.Ceramics International，2000，26：485-493.
Disclosure of Invention
The invention aims to provide a method for preparing bimetallic oxide and hydrotalcite by using Bayer red mud as a raw material.
The Bayer red mud comprises the following chemical components: al (Al)2O3：22～25％；SiO2：16～19％；Fe2O3：32～39％；CaO：0～2％；Na2O：8～13％；TiO2: 7-9%; (see reference for details [1]])
The method for preparing the bimetallic oxide by taking the Bayer red mud as the raw material comprises the following steps
1) Grinding hydroxide or oxide of divalent metal elements which is 0.5-3 times of the dry weight of the red mud to be smaller than 300 meshes, adding the hydroxide or oxide and the red mud into a stirrer, adding water which is 2-8 times of the dry weight of the red mud, and uniformly stirring to prepare ore pulp;
2) dewatering the ore pulp, drying in the air or dryingat a temperature lower than 90 ℃, and calcining at 450-750 ℃ to 2-EGrinding for 5 hours to less than 200 meshes for later use, wherein the obtained product is a bimetal oxide with a chemical structural general formula of Mm (Al, Fe)3+) n.ox, wherein M is one of magnesium, zinc and nickel, and x is M +3 n/2.
The method for preparing the hydrotalcite by using the Bayer red mud as the raw material comprises the following steps:
1) grinding hydroxide or oxide of divalent metal elements which is 0.5-3 times of the dry weight of the red mud to be smaller than 300 meshes, adding the hydroxide or oxide and the red mud into a stirrer, adding water which is 2-8 times of the dry weight of the red mud, and uniformly stirring to prepare ore pulp;
2) dewatering the ore pulp, airing or drying at a temperature lower than 90 ℃, calcining for 2-5 hours at a temperature of 450-750 ℃, grinding to less than 200 meshes for later use, wherein the obtained product is a bimetal oxide, and the general chemical structure formula of the bimetal oxide is Mm (Al, Fe)3+) n.ox, wherein M is one of magnesium, zinc and nickel, and x is M +3 n/2;
3) preparing soluble carbonate or bicarbonate into a solution with the concentration of 0.5-2 mol/L, adding the product obtained in the step 2) into the solution according to the proportion of adding 200-300 g of bimetallic oxide into each gram of molecular carbonate or bicarbonate, uniformly mixing, continuously stirring for 5-10 hours, filtering or centrifugally dewatering, washing for 2-3 times with clean water, dewatering, airing or drying at the temperature lower than 90 ℃, and grinding to less than 200 meshes for later use, wherein the obtained product is hydrotalcite, and the chemical structural general formula of the hydrotalcite is as follows: [ M]A1-x(Al，Fe3+)x(OH)2]X+[(CO3)x/2·nH2O]，X＝0.5～0.17；M/(Al+Fe3+)＝1～5。
The divalent metal element refers to one or more of magnesium, zinc and nickel, and the hydroxide or oxide thereof can be natural minerals or commercial products.
The soluble carbonate or bicarbonate is one or more of sodium carbonate, ammonium carbonate, sodium bicarbonate, ammonium bicarbonate, sodium carbonate hydrate or ammonium carbonate hydrate.
The invention has the advantages of simple process flow and less equipment investment; the main raw materials have wide sources and low price. Compared with the existing coprecipitation method, the method simplifies the production process, adopts natural minerals and industrial wastes as raw materials, greatly reduces the cost and consumption, and solves the problems of stacking of a large amount of red mud and environmental harm. The obtained product bimetal oxide and hydrotalcite can be used as a catalyst and a catalyst carrier in the fields of chemistry and chemical engineering; in the field of functional materials, as infrared and ultraviolet absorbing and blocking materials; in the plastic industry, can be used as an antibacterial additive, a flame retardant and a PVC stabilizer; in the field of environmental protection, they have a strong adsorption effect on many toxic and harmful anions, and thus can be used for water purification, sewage treatment, pollution control and environmental remediation.
Detailed Description
The basis for preparing bimetallic oxides and hydrotalcite from Bayer red mud is that Al and Fe (III) contained in the red mud and added divalent metal hydroxides and oxides can form solid melts during high-temperature calcination, and the solid melts can be hydrolyzed into hydrotalcite in an aqueous solution of carbonate.
The ratio of the divalent metal element in the additive to the trivalent metal element in the red mud has certain influence on the performance of the final product. Generally, when the former is used in a higher amount, the crystal structure of the product is more stable; when the latter is used in high amount, the product has better adsorption performance. The molar ratio of the divalent to trivalent metal elements is preferably controlled to be in the range of 1: 1 to 4: 1. In practical application, the dry weight ratio of the additive to the red mud can be controlled between 0.5: 1 and 3: 1. The most commonly used hydroxides and oxides of divalent elements are Mg (OH)2And MgO, which may be a natural mineral or a commercially available product. The additive should be ground to less than 300 mesh prior to dosing.
The water adding amount can be adjusted according to the drying degree of the red mud, so that the product after stirring is sticky and flowable ore pulp. The water consumption is too low, and the raw materials are difficult to stir uniformly; the water consumption is too high, which greatly increases the energy consumption of the subsequent process and the equipment abrasion. The recommended water consumption is 3-5 times of the feeding amount.
Because the hydroxide and the oxide of the divalent element have slight solubility, the hydroxide and the oxide are easy to be uniformly mixed with the components in the red mud in the stirring process.
The stirred ore pulp can be dehydrated by methods such as filtration, filter pressing or centrifugation, natural drying is adopted as far as possible, or drying is carried out at the temperature of not more than 90 ℃, so that the ore pulp can be further aged in the drying process. The purpose of calcination is to convert the raw mixture into a solid solution. The calcined product is a bimetal oxide, can be directly put on the market as a product, and can also be used as a raw material for further synthesizing the hydrotalcite.
And (3) hydrolyzing the bimetallic oxide in a carbonate solution to obtain the hydrotalcite. Representative chemical reactions in solution are:
the molar ratio of LDO to carbonate in the reaction is 1: 1, and the molar amount of carbonate is controlled to be 1.2-1.5 times of that of LDO, so as to ensure the complete reaction. The kind of carbonate has little influence on the hydrolysis reaction. For cost reasons, it is preferred to use NaCO3. And (3) washing the hydrolysate for 2-3 times after dehydration to remove excessive carbonate.
The present invention is further illustrated by the following examples.
Example 1: bimetallic oxides are prepared from brucite and bayer red mud.
1) Weighing 50 kg of brucite, grinding to less than 300 meshes, weighing 50 kg of Bayer red mud dry powder, adding into a stirrer, adding 350 kg of water, and stirring uniformly;
2) and (3) putting the mixture on a filter cloth, filtering and dehydrating, calcining for 3 hours at 500 ℃ after air drying, cooling and grinding to less than 200 meshes for later use.
Example 2: bimetallic oxides are prepared from magnesite and bayer red mud.
1) Weighing 150 kg of magnesite, heating to 400 ℃, and keeping the temperature for 3 hours to decompose the magnesite into MgO;
2) weighing 50 kg of Bayer red mud dry powder, adding the Bayer red mud dry powder and MgO obtained in the previous step into a stirrer, adding 500 kg of water, and uniformly stirring;
3) and (3) putting the mixture on a filter cloth, filtering and dehydrating, calcining for 3 hours at 450 ℃ after air drying, cooling and grinding to less than 200 meshes for later use.
Example 3: bimetallic oxides were prepared from commercial zinc oxide and bayer red mud.
1) Weighing 60 kg of commercial zinc oxide and 100 kg of dry Bayer red mud powder, adding the commercial zinc oxide and the dry Bayer red mud powder into a stirrer, adding 600 kg of water, and stirring uniformly;
2) and (3) putting the mixture on a filter cloth, filtering and dehydrating, calcining for 4 hours at 750 ℃ after air drying, cooling and grinding to less than 200 meshes for later use.
Example 4: bimetallic oxides were prepared from commercial NiO and bayer red mud.
1) Weighing 60 kg of commercial nickel oxide and 100 kg of dry Bayer red mud powder, adding the commercial nickel oxide and the dry Bayer red mud powder into a stirrer, adding 500 kg of water, and uniformly stirring;
2) and (3) putting the ground mixture on a filter cloth, filtering and dehydrating, calcining for 2 hours at 500 ℃ after air drying, cooling and grinding to less than 200 meshes for later use.
Example 5: hydrotalcite is prepared from bimetallic oxides.
1) Weighing 150 kg of sodium carbonate, adding one ton of water, fully stirring to completely dissolve the sodium carbonate, adding 400 kg of bimetallic oxide into the solution, uniformly mixing, and continuously stirring for 6 hours;
2) after filtering and dehydrating, adding one ton of water, fully stirring to uniformly mix, filtering again, and repeating the steps;
3) or oven drying at 80 deg.C, grinding to less than 200 mesh, and packaging.
Example 6: hydrotalcite is prepared from bimetallic oxides.
1) Weighing 150 kg of sodium bicarbonate, adding one ton of water, fully stirring to completely dissolve the sodium bicarbonate, adding 300 kg of bimetallic oxide into the solution, uniformly mixing, and continuously stirring for 8 hours;
2) after filtering and dehydrating, adding one ton of water, fully stirring to uniformly mix, filtering again, and repeating the steps;
3) or oven drying at 80 deg.C, grinding to less than 200 mesh, and packaging.
Example 7: hydrotalcite is prepared from bimetallic oxides.
1) Weighing 100 kg of ammonium carbonate, adding one ton of water, fully stirring to completely dissolve the ammonium carbonate, adding 300 kg of bimetallic oxide into the solution, uniformly mixing, and continuously stirring for 7 hours;
2) after filtering and dehydrating, adding one ton of water, fully stirring to uniformly mix, filtering again, and repeating the steps;
3) or oven drying at 80 deg.C, grinding to less than 200 mesh, and packaging.
Example 8: hydrotalcite is prepared from bimetallic oxides.
1) Weighing 150 kg of ammonium bicarbonate, adding one ton of water, fully stirring to completely dissolve the ammonium bicarbonate, adding 350 kg of bimetallic oxide into the solution, uniformly mixing, and continuously stirring for 8 hours;
2) after filtering and dehydrating, adding one ton of water, fully stirring to uniformly mix, filtering again, and repeating the steps;
3) or oven drying at 80 deg.C, grinding to less than 200 mesh, and packaging.
Claims (3)
1. A method for preparing bimetallic oxide by using Bayer red mud as a raw material is characterized by comprising the following steps:
1) grinding hydroxide or oxide of divalent metal elements which is 0.5-3 times of the dry weight of the red mud to be smaller than 300 meshes, adding the hydroxide or oxide and the red mud into a stirrer, adding water which is 2-8 times of the dry weight of the red mud, and uniformly stirring to prepare ore pulp;
2) dewatering the ore pulp, airing or drying at a temperature lower than 90 ℃, calcining for 2-5 hours at a temperature of 450-750 ℃, grinding to less than 200 meshes for later use, wherein the obtained product is a bimetal oxide, and the general chemical structure formula of the bimetal oxide is Mm (Al, Fe)3+) n.ox, wherein M is one of magnesium, zinc and nickel, and x is M +3 n/2.
2. A method for preparing hydrotalcite by using Bayer red mud as a raw material is characterized by comprising the following steps:
1) grinding hydroxide or oxide of divalent metal elements which is 0.5-3 times of the dry weight of the red mud to be smaller than 300 meshes, adding the hydroxide or oxide and the red mud into a stirrer, adding water which is 2-8 times of the dry weight of the red mud, and uniformly stirring to prepare ore pulp;
2) dewatering the ore pulp, airing or drying at a temperature lower than 90 ℃, calcining for 2-5 hours at a temperature of 450-750 ℃, grinding to less than 200 meshes for later use, wherein the obtained product is a bimetal oxide, and the general chemical structure formula of the bimetal oxide is Mm (Al, Fe)3+) n.ox, wherein M is one of magnesium, zinc and nickel, and x is M +3 n/2;
3) preparing soluble carbonate or bicarbonate into a solution with the concentration of 0.5-2 mol/L, adding the product obtained in the step 2) into the solution according to the proportion of adding 200-300 g of bimetallic oxide into each gram of molecular carbonate or bicarbonate, uniformly mixing, continuously stirring for 5-10 hours, filtering or centrifugally dewatering, washing for 2-3 times with clean water, dewatering, airing or drying at the temperature lower than 90 ℃, and grinding to less than 200 meshes for later use, wherein the obtained product is hydrotalcite, and the chemical structural general formula of the hydrotalcite is as follows: [ M]A1-x(Al，Fe3+)x(OH)2]X+[(CO3)x/2·nH2O]，X＝0.5～0.17；M/(Al+Fe3+)＝1～5。
3. The method of claim 2, wherein the soluble carbonate or bicarbonate is one or more of sodium carbonate, ammonium carbonate, sodium bicarbonate, ammonium bicarbonate, sodium carbonate hydrate, or ammonium carbonate hydrate.
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN101624457B (en) * | 2008-07-09 | 2011-07-27 | 北京理工大学 | Environmental protection based red mud combination modification synergism fire-retardant polyethylene |
| CN102585845B (en) * | 2010-12-31 | 2014-04-09 | 梁清源 | Inorganic mineral composite flame retardant and preparation method thereof |
| CN103464090B (en) * | 2013-08-21 | 2016-10-05 | 青岛科技大学 | Red mud modification method, modified substance and application of modified substance in adsorption of brilliant blue dye |
| CN110204788A (en) * | 2019-06-13 | 2019-09-06 | 湘潭大学 | A kind of preparation method of alginate/hydrotalcite flame retardant composite material |
| CN112850793A (en) * | 2021-02-11 | 2021-05-28 | 贵州大学 | High-value utilization method of red mud |
| CN113716588B (en) * | 2021-08-17 | 2023-04-18 | 湖南恒光化工有限公司 | Low-cost preparation method of magnesium-aluminum hydrotalcite |
| CN115259095B (en) * | 2022-07-13 | 2023-11-07 | 塔里木大学 | Method for preparing hydrotalcite type layered hydroxide by using saline-alkali soil and application |
| CN115745003A (en) * | 2022-12-02 | 2023-03-07 | 华北科技学院 | Iron-magnesium-aluminum carbonate type hydrotalcite material prepared from red mud as well as preparation method and application thereof |
| CN116444054B (en) * | 2023-06-14 | 2023-08-29 | 济南山源环保科技有限公司 | Boiler water treatment agent and preparation method thereof |
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