CN110803717B - Method for carrying out reduction pre-magnetization on calcium iron garnet hydrate based on aqueous solution - Google Patents
Method for carrying out reduction pre-magnetization on calcium iron garnet hydrate based on aqueous solution Download PDFInfo
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- C01—INORGANIC CHEMISTRY
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- C01G49/009—Compounds containing, besides iron, two or more other elements, with the exception of oxygen or hydrogen
Abstract
A method for carrying out reduction pre-magnetization on hydrated calcium iron garnet based on aqueous solution, belonging to the field of red mud recovery. The method comprises the following steps: mixing the hydrated calcium iron garnet which is a solid waste generated by the high-pressure hydration treatment of the red mud with water, pouring the mixture into a high-temperature high-pressure reaction kettle, and sealing the reaction kettle; introducing inert gas to evacuate air, introducing high-pressure reducing gas to reach pressure P, heating to 80-260 ℃, reducing at constant temperature and constant pressure to perform pre-magnetization to obtain pre-magnetized hydrated calcium iron garnet; the pressure P is 1.0< P is less than or equal to 3.0 atm; the pre-magnetization time is more than or equal to 30 min; after the reduction and pre-magnetization are finished, reducing the pressure of the high-temperature and high-pressure reaction kettle to normal pressure, introducing inert gas, and diluting until the content of the reducing gas is below the safe content value in the air; and (3) carrying out magnetic separation on the obtained pre-magnetized hydrated calcium iron garnet, wherein the iron separation rate is 65-70%. The method realizes the utilization of the hydrated calcium iron garnet generated after the high-pressure hydration treatment of the red mud, and has simple operation and high added value of products.
Description
Technical Field
The invention relates to the technical field of red mud recovery, in particular to a method for carrying out reduction pre-magnetization on hydrated calcium iron garnet based on an aqueous solution.
Background
The red mud is industrial solid waste in the process of producing alumina from bauxite, and 1.0-1.8 t of red mud is generally produced every 1t of alumina is produced. It is called red mud because it contains pure ferric oxide in free state and shows red color. The red mud produced by the prior art (Bayer process or sintering process) contains a large amount of Na2O·Al2O3·1.7SiO2·nH2And O has the characteristic of strong basicity (sodium oxide: silicon oxide is approximately equal to 1.0 according to the mass ratio). The disposal method is mainly piled up in a storage yard for a long time, not only needs certain capital construction cost, but also occupies a large amount of land, a large amount of valuable metal ores and rich alkali liquor can not be reasonably utilized, and the environment is polluted, so that the land is alkalized, and the underground water is polluted. The comprehensive utilization of red mud, although being studied by many people, is also useful for producing cement, bricks, tiles, insulating bricks, microporous calcium silicate and other building materials, such as building additives used in the field of building materials. However, because calcium-containing silicate is added in the process of manufacturing cement, the micro-dissociated calcium ions can promote Na in the red mud2O·Al2O3·1.7SiO2·nH2The precipitation of sodium ions in O enables the material developed above to be used in the processThere is a problem of alkali return, which causes many problems, making these materials prepared from red mud impractical for practical use.
The red mud produced by the existing process is further treated by a high-pressure hydration method, and the product is hydrated calcium iron garnet (3 CaO. Fe)2O3·nSiO2·mH2O (n-1-2)), and the hydrated calcium iron garnet contains low alkali (sodium-silicon ratio)<0.002 (mass ratio of sodium oxide to silicon oxide)) and high iron content (total iron content is more than or equal to 20 percent). Although the product solves the problem of high alkali content of red mud, the product cannot be effectively applied. This is because the hydrated calcium iron garnet contains silica and a high amount of water cannot be applied to iron making; compared with ceramic materials, the iron content of the cement is too high (the total iron content of the cement is required to be less than or equal to 7 percent), and the cement cannot be applied to building materials. In addition, the hydrated calcium iron garnet is a compound of calcium oxide, silicon oxide and iron oxide with crystal water, wherein the iron oxide has low activity, does not exist in a free pure substance form like ferric oxide in the traditional red mud, and cannot be directly separated by magnetic separation after being subjected to reduction pre-magnetization like the red mud. However, the hydrated calcium iron garnet has fine particles (particle size)<20 microns) and has large surface energy and high activity. If the characteristics of small particles, large surface energy, high activity and high iron content can be fully utilized, the comprehensive utilization value of the iron-containing composite material is greatly improved. And the hydrated calcium iron garnet has fine particles and is easy to agglomerate at high temperature. The pre-magnetization powder is dispersed in water, does not agglomerate among particles, is favorable for improving the pre-magnetization speed at a lower temperature, and can be widely applied.
Disclosure of Invention
The invention provides a method for carrying out reduction and pre-magnetization on hydrated calcium iron garnet based on an aqueous solution. The method ensures that the conversion rate of converting the ferric oxide in the hydrated calcium iron garnet into the ferroferric oxide is more than 95 percent, the pre-magnetized product can be used for magnetic separation, and the iron separation rate is more than or equal to 65 percent. The method realizes the utilization of the hydrated calcium iron garnet produced after the high-pressure hydration treatment of the red mud, has simple operation and high added value of products, and can greatly improve the high added value effective utilization of the red mud.
The invention is realized by the following technical scheme:
the invention relates to a method for carrying out reduction pre-magnetization on hydrated calcium iron garnet based on an aqueous solution, which comprises the following steps:
step 1: mixing material
Mixing hydrated calcium iron garnet with water to obtain a mixed solution; pouring the mixed solution into a high-temperature high-pressure reaction kettle, and sealing;
step 2: reducing pre-magnetization
Introducing inert gas into the high-temperature high-pressure reaction kettle to evacuate air, introducing high-pressure reducing gas into the mixed solution to reach a pressure P, heating to 80-260 ℃, reducing at constant temperature and constant pressure to carry out pre-magnetization to obtain pre-magnetized hydrated calcium iron garnet; wherein the pressure P is 1.0< P is less than or equal to 3.0 atm; the pre-magnetization time is more than or equal to 30 min;
and step 3: reducing blood pressure
After reduction and pre-magnetization are finished, reducing the pressure of the high-temperature high-pressure reaction kettle to normal pressure, introducing inert gas into the high-temperature high-pressure reaction kettle, and diluting until the content of the reducing gas is below the safe content value in the air;
and 4, step 4: separation of
And (3) carrying out magnetic separation on the obtained pre-magnetized hydrated calcium iron garnet, wherein the iron separation rate is 65-70%.
In the step 1, the hydrated calcium iron garnet is solid waste generated after the red mud is subjected to high-pressure hydration treatment.
In the step 1, according to the volume ratio, the calcium iron garnet hydrate: the water is less than or equal to 2: 3.
In the step 1, in order to ensure the treatment scale, the calcium iron garnet hydrate is preferably selected according to the volume ratio: and 3 is selected from water (1-2).
In the step 1, the chemical formula of the hydrated calcium iron garnet is as follows: 3 CaO. Fe2O3·nSiO2·mH2O, wherein n is 1-2, m is a positive integer, and m is more than or equal to 1; particle size<20 μm, by mass, of Na2O：SiO2<0.002。
In the step 2, the inert gas is argon or argon-nitrogen mixed gas.
In the step 2, the reducing gas is a reducing gas capable of reducing hydrated calcium iron garnet at normal temperature and normal pressure meeting thermodynamic calculation, and is preferably CO, natural gas, blast furnace gas or H2One or more of the above;
in the step 2, the main component of the natural gas is CH4The volume purity is more than or equal to 98 percent; the main components of the blast furnace gas are CO and H2CO and H2The volume purity of the product is more than or equal to 98 percent; the volume purity of the CO is more than or equal to 98 percent; said H2The volume purity of the product is more than or equal to 98 percent.
In the step 2, electric heating or high-temperature oil bath heating is adopted for heating.
In the step 2, the conversion rate of converting iron oxide in the pre-magnetized hydrated calcium iron garnet into ferroferric oxide is more than or equal to 95%.
In the step 2, the pre-magnetization time is preferably 3-20 h.
In the step 3, the inert gas is argon and/or nitrogen.
In the step 3, the value of the safe content of the reducing gas in the air is determined according to the explosion limit of the combustible gas in the air.
In the invention, the solution after magnetic separation is subjected to solid-liquid separation, the liquid can be reused as water for mixing hydrated calcium-iron-garnet for recycling, and the filtered solid is magnetic separation slag and can be used as a cement material.
The invention relates to a method for carrying out reduction pre-magnetization on hydrated calcium iron garnet based on an aqueous solution, which relates to a chemical reaction equation as follows: 3Fe2O3+CO(g)＝2Fe3O4+CO2(g) Or 12Fe2O3+CH4(g)＝8Fe3O4+CO2(g)+2H2O or 3Fe2O3+5H2(g)＝2Fe3O4+5H2And O. Thermodynamic calculations show that the chemical reactions can proceed spontaneously at normal temperature and pressure. In practice, however, the kinetic rate is very slowThus, it is not practical.
The invention is carried out under relatively high pressure, and can improve reducing agent CO or natural gas (CH)4) Or blast furnace gas (CO + H)2) Or H2Partial pressure and improved activity, which is favorable for promoting the forward progress of the reaction, accelerating the reaction rate and improving the conversion rate of reducing the ferric oxide in the hydrated calcium iron garnet into the ferroferric oxide. The method adopts hydrated calcium iron garnet, wherein Si is a stable crystal lattice formed by atoms, Ca, Fe and O, and SiO is2Not existing in a traditional free mode, part of ferric iron is reduced into ferrous iron during gas-solid-liquid three-phase interface reaction, oxygen ions form water molecules to leave, and meanwhile, the water molecules in the hydrated calcium iron garnet also leave. The process causes the collapse of the original stable crystal lattice, and the high-pressure water environment is favorable for the nucleation and growth of the generated ferroferric oxide into a simple substance.
The conversion rate of ferric oxide reduced and pre-magnetized in the hydrated calcium iron garnet to ferroferric oxide is more than or equal to 95 percent, and the pre-magnetized product is subjected to magnetic separation, so that the separation rate of iron is 70 to 65 percent. The invention greatly improves the large-scale material application of the red mud, is beneficial to reducing the existing alumina production source, is beneficial to environmental protection and has high added value.
Detailed Description
The present invention will be described in further detail with reference to examples.
In the following examples, the total iron content of the adopted hydrated calcium iron garnet is more than or equal to 20% by mass, and the sodium oxide: silicon oxide < 0.002.
In the following examples, natural gas was used whose main component was CH4The volume purity is more than or equal to 98 percent; the blast furnace gas used comprises CO and H as main components2CO and H2The volume purity of the product is more than or equal to 98 percent; the volume purity of the adopted CO is more than or equal to 98 percent; by the use of H2The volume purity of the product is more than or equal to 98 percent.
Example 1
A method for carrying out reduction pre-magnetization on hydrated calcium iron garnet based on aqueous solution comprises the following steps:
step 1: mixing material
Mixing 2 volumes of hydrated calcium iron garnet with 3 volumes of water to obtain a mixed solution; pouring the mixed solution into a high-temperature high-pressure reaction kettle, and sealing;
step 2: reducing pre-magnetization
Introducing Ar into a high-temperature high-pressure reaction kettle, evacuating air in the high-temperature high-pressure reaction kettle, inserting a pipe orifice into which reducing gas is introduced into the mixed solution, introducing high-pressure CO into the high-temperature high-pressure reaction kettle to ensure that the pressure of the high-temperature high-pressure reaction kettle is 3.0atm, heating to 260 ℃ by adopting electric heating, reducing for 20 hours at constant temperature and constant pressure, and pre-magnetizing to obtain pre-magnetized hydrated calcium iron garnet;
and step 3: reducing blood pressure
After reduction and pre-magnetization are finished, reducing the pressure of the high-temperature high-pressure reaction kettle to normal pressure, introducing argon into the high-temperature high-pressure reaction kettle, and diluting until the content of the reduction gas CO is below the safe content value in the air;
and 4, step 4: separation of
Opening the reaction kettle, and carrying out magnetic separation on the obtained low sodium calcium iron garnet hydrate after pre-magnetization; .
And 5:
and (3) carrying out solid-liquid separation on the solution after magnetic separation, wherein the liquid can be used as water for pre-magnetizing and mixing the hydrated calcium-iron garnet again for recycling, and the filtered solid is magnetic separation slag and can be used as a cement material.
In the present example, the conversion rate of converting the iron sesquioxide in the hydrated calcium iron garnet into the magnetic separation ferroferric oxide is 99.9%, and the separation rate of the magnetic separation iron is 70%.
Example 2
A method for carrying out reduction pre-magnetization on hydrated calcium iron garnet based on an aqueous solution, which is the same as the example 1 and is characterized in that:
step 1: mixing material
1 volume of hydrated calcium iron garnet was mixed with 2 volumes of water.
The other ways are the same.
In the present embodiment, the conversion rate of converting the iron sesquioxide into the magnetic separation ferroferric oxide in the calcium iron garnet hydrate is 98%, and the separation rate of the magnetic separation iron is 67%.
Example 3
A method for carrying out reduction pre-magnetization on hydrated calcium iron garnet based on an aqueous solution, which is the same as the example 1, and is characterized in that:
step 2: reducing pre-magnetization
The pressure of the high-pressure CO is 2.0 atm;
the other ways are the same.
In the present example, the conversion rate of converting the iron sesquioxide into the magnetic separation ferroferric oxide in the hydrated calcium iron garnet is 97%, and the separation rate of the magnetic separation iron is 67%.
Example 4
A method for carrying out reduction pre-magnetization on hydrated calcium iron garnet based on an aqueous solution, which is the same as the example 1, and is characterized in that:
step 2: reducing pre-magnetization
The pressure of the high-pressure CO is 1.1 atm;
the other ways are the same.
In the present example, the conversion rate of converting the iron sesquioxide into the magnetic separation ferroferric oxide is 96%, and the separation rate of the magnetic separation iron is 66%.
Example 5
A method for carrying out reduction pre-magnetization on hydrated calcium iron garnet based on an aqueous solution, which is the same as the example 1, and is characterized in that:
step 2: reducing pre-magnetization
Reducing for 3 hours at constant temperature and constant pressure;
the other ways are the same.
In the present embodiment, the conversion rate of converting the iron sesquioxide into the magnetic separation ferroferric oxide in the calcium iron garnet hydrate is 98%, and the separation rate of the magnetic separation iron is 65%.
Example 6
A method for carrying out reduction pre-magnetization on hydrated calcium iron garnet based on an aqueous solution, which is the same as the example 1, and is characterized in that:
step 2: reducing pre-magnetization
Reducing for 5 hours at constant temperature and constant pressure;
the other ways are the same.
In the present embodiment, the conversion rate of converting the iron sesquioxide into the magnetic separation ferroferric oxide in the calcium iron garnet hydrate is 98%, and the separation rate of the magnetic separation iron is 66%.
Example 7
A method for carrying out reduction pre-magnetization on hydrated calcium iron garnet based on an aqueous solution, which is the same as the example 1, and is characterized in that:
step 2: reducing pre-magnetization
Reducing for 10 hours at constant temperature and constant pressure;
the other ways are the same.
In the present embodiment, the conversion rate of converting the iron sesquioxide into the magnetic separation ferroferric oxide in the calcium iron garnet hydrate is 98%, and the separation rate of the magnetic separation iron is 67%.
Example 8
A method for carrying out reduction pre-magnetization on hydrated calcium iron garnet based on an aqueous solution, which is the same as the example 1, and is characterized in that:
step 2: reducing pre-magnetization
Reducing for 15h at constant temperature and constant pressure;
the other ways are the same.
In the present embodiment, the conversion rate of converting the iron sesquioxide into the magnetic separation ferroferric oxide in the calcium iron garnet hydrate is 98%, and the separation rate of the magnetic separation iron is 68%.
Example 9
A method for carrying out reduction pre-magnetization on hydrated calcium iron garnet based on an aqueous solution, which is the same as example 3, and is characterized in that:
step 2: reducing pre-magnetization
Reducing for 3 hours at constant temperature and constant pressure;
the other ways are the same.
In the present embodiment, the conversion rate of converting the iron sesquioxide into the magnetic separation ferroferric oxide in the calcium iron garnet hydrate is 98%, and the separation rate of the magnetic separation iron is 65%.
Example 10
A method for carrying out reduction pre-magnetization on hydrated calcium iron garnet based on an aqueous solution, which is the same as example 3, and is characterized in that:
step 2: reducing pre-magnetization
Reducing for 5h at constant temperature and constant pressure;
the other ways are the same.
In the present example, the conversion rate of converting the iron sesquioxide into the magnetic separation ferroferric oxide in the hydrated calcium iron garnet is 99%, and the separation rate of the magnetic separation iron is 66%.
Example 11
A method for carrying out reduction pre-magnetization on hydrated calcium iron garnet based on an aqueous solution, which is the same as example 3, and is characterized in that:
step 2: reducing pre-magnetization
Reducing for 10 hours at constant temperature and constant pressure;
the other ways are the same.
In the present example, the conversion rate of converting the iron sesquioxide into the magnetic separation ferroferric oxide in the hydrated calcium iron garnet is 99%, and the separation rate of the magnetic separation iron is 66%.
Example 12
A method for carrying out reduction pre-magnetization on hydrated calcium iron garnet based on an aqueous solution, which is the same as example 3, and is characterized in that:
step 2: reducing pre-magnetization
Reducing for 15h at constant temperature and constant pressure;
the other ways are the same.
In the present example, the conversion rate of converting the iron sesquioxide into the magnetic separation ferroferric oxide is 99%, and the separation rate of the magnetic separation iron is 67%.
Example 13
A method for carrying out reduction pre-magnetization on hydrated calcium iron garnet based on an aqueous solution, which is the same as example 5, and is characterized in that:
step 2: reducing pre-magnetization
Reducing for 15h at constant temperature and constant pressure;
the other ways are the same.
In the present embodiment, the conversion rate of converting the iron sesquioxide into the magnetic separation ferroferric oxide in the hydrated calcium iron garnet is 99%, and the separation rate of the magnetic separation iron is 68%.
Example 14
A method for carrying out reduction pre-magnetization on hydrated calcium iron garnet based on an aqueous solution, which is the same as example 4, and is characterized in that:
step 2: reducing pre-magnetization
Reducing for 10 hours at constant temperature and constant pressure;
the other ways are the same.
In the present embodiment, the conversion rate of converting the iron sesquioxide into the magnetic separation ferroferric oxide in the calcium iron garnet hydrate is 98%, and the separation rate of the magnetic separation iron is 66%.
Example 15
A method for carrying out reduction pre-magnetization on hydrated calcium iron garnet based on an aqueous solution, which is the same as example 4, and is characterized in that:
step 2: reducing pre-magnetization
Reducing for 5 hours at constant temperature and constant pressure;
the other ways are the same.
In the present embodiment, the conversion rate of converting the iron sesquioxide into the magnetic separation ferroferric oxide in the calcium iron garnet hydrate is 98%, and the separation rate of the magnetic separation iron is 66%.
Example 16
A method for carrying out reduction pre-magnetization on hydrated calcium iron garnet based on an aqueous solution, which is the same as example 5, and is characterized in that:
step 2: reducing pre-magnetization
Reducing for 3 hours at constant temperature and constant pressure;
the other ways are the same.
In the present embodiment, the conversion rate of converting the iron sesquioxide into the magnetic separation ferroferric oxide in the calcium iron garnet hydrate is 98%, and the separation rate of the magnetic separation iron is 65%.
Example 17
A method for carrying out reduction pre-magnetization on hydrated calcium iron garnet based on an aqueous solution, which is the same as the example 1, and is characterized in that:
step 2: reducing pre-magnetization
Heating to 110 ℃, and reducing at constant temperature and constant pressure;
the other ways are the same.
In the present example, the conversion rate of converting the iron sesquioxide into the magnetic separation ferroferric oxide is 96%, and the separation rate of the magnetic separation iron is 66%.
Example 18
A method for carrying out reduction pre-magnetization on hydrated calcium iron garnet based on an aqueous solution, which is the same as example 17 and is characterized in that:
step 2: reducing pre-magnetization
Reducing for 15h at constant temperature and constant pressure;
the other ways are the same.
In the present example, the conversion rate of converting the iron sesquioxide into the magnetic separation ferroferric oxide in the hydrated calcium iron garnet is 96%, and the separation rate of the magnetic separation iron is 66.5%.
Example 19
A method for carrying out reduction pre-magnetization on hydrated calcium iron garnet based on an aqueous solution, which is the same as example 17 and is characterized in that:
step 2: reducing pre-magnetization
Reducing for 10 hours at constant temperature and constant pressure;
the other ways are the same.
In the present example, the conversion rate of converting the iron sesquioxide into the magnetic separation ferroferric oxide is 96%, and the separation rate of the magnetic separation iron is 66%.
Example 20
A method for carrying out reduction pre-magnetization on hydrated calcium iron garnet based on an aqueous solution, which is the same as example 17 and is characterized in that:
step 2: reducing pre-magnetization
Reducing for 5 hours at constant temperature and constant pressure;
the other ways are the same.
In the present example, the conversion rate of converting the iron sesquioxide into the magnetic separation ferroferric oxide in the hydrated calcium iron garnet is 95%, and the separation rate of the magnetic separation iron is 65%.
Example 21
A method for carrying out reduction pre-magnetization on hydrated calcium iron garnet based on an aqueous solution, which is the same as example 17 and is characterized in that:
step 2: reducing pre-magnetization
Reducing for 3 hours at constant temperature and constant pressure;
the other ways are the same.
In the present example, the conversion rate of converting the iron sesquioxide into the magnetic separation ferroferric oxide in the hydrated calcium iron garnet is 95%, and the separation rate of the magnetic separation iron is 65%.
Example 22
A method for carrying out reduction pre-magnetization on hydrated calcium iron garnet based on an aqueous solution, which is the same as the example 1, and is characterized in that:
step 2: reducing pre-magnetization
Heating to 100 ℃, and reducing at constant temperature and constant pressure;
the other ways are the same.
In the present example, the conversion rate of converting the iron sesquioxide into the magnetic separation ferroferric oxide in the hydrated calcium iron garnet is 95%, and the separation rate of the magnetic separation iron is 66%.
Example 23
A method for carrying out reduction pre-magnetization on hydrated calcium iron garnet based on an aqueous solution, which is different from the method in example 22 in that:
step 2: reducing pre-magnetization
Reducing for 15h at constant temperature and constant pressure;
the other ways are the same.
In the present example, the conversion rate of converting the iron sesquioxide into the magnetic separation ferroferric oxide is 96%, and the separation rate of the magnetic separation iron is 66%.
Example 25
A method for carrying out reduction pre-magnetization on hydrated calcium iron garnet based on an aqueous solution, which is the same as example 23, and is characterized in that:
step 2: reducing pre-magnetization
Reducing for 10 hours at constant temperature and constant pressure;
the other ways are the same.
In the present example, the conversion rate of converting the iron sesquioxide into the magnetic separation ferroferric oxide in the hydrated calcium iron garnet is 95.5%, and the separation rate of the magnetic separation iron is 65.5%.
Example 25
A method for carrying out reduction pre-magnetization on hydrated calcium iron garnet based on an aqueous solution, which is different from the method in example 22 in that:
step 2: reducing pre-magnetization
Reducing for 3 hours at constant temperature and constant pressure;
the other ways are the same.
In the present example, the conversion rate of converting the iron sesquioxide into the magnetic separation ferroferric oxide in the hydrated calcium iron garnet is 95%, and the separation rate of the magnetic separation iron is 65%.
Example 26
A method for carrying out reduction pre-magnetization on hydrated calcium iron garnet based on an aqueous solution, which is the same as the example 1, and is characterized in that:
step 2: reducing pre-magnetization
Heating to 90 ℃, and reducing at constant temperature and constant pressure;
the other ways are the same.
In the present example, the conversion rate of converting the iron sesquioxide into the magnetic separation ferroferric oxide in the hydrated calcium iron garnet is 95.5%, and the separation rate of the magnetic separation iron is 65%.
Example 27
A method for carrying out reduction pre-magnetization on hydrated calcium iron garnet based on an aqueous solution, which is different from the method in example 26 in that:
step 2: reducing pre-magnetization
Reducing for 15h at constant temperature and constant pressure;
the other ways are the same.
In the present example, the conversion rate of converting the iron sesquioxide into the magnetic separation ferroferric oxide in the hydrated calcium iron garnet is 96%, and the separation rate of the magnetic separation iron is 65.5%.
Example 28
A method for carrying out reduction pre-magnetization on hydrated calcium iron garnet based on an aqueous solution, which is different from the method in example 26 in that:
step 2: reducing pre-magnetization
Reducing for 10 hours at constant temperature and constant pressure;
the other ways are the same.
In the present example, the conversion rate of converting the iron sesquioxide into the magnetic separation ferroferric oxide in the hydrated calcium iron garnet is 95.5%, and the separation rate of the magnetic separation iron is 65.5%.
Example 29
A method for carrying out reduction pre-magnetization on hydrated calcium iron garnet based on an aqueous solution, which is different from the method in example 26 in that:
step 2: reducing pre-magnetization
Reducing for 3 hours at constant temperature and constant pressure;
the other ways are the same.
In the present example, the conversion rate of converting the iron sesquioxide into the magnetic separation ferroferric oxide in the hydrated calcium iron garnet is 95%, and the separation rate of the magnetic separation iron is 65%.
Example 30
A method for carrying out reduction pre-magnetization on hydrated calcium iron garnet based on an aqueous solution, which is the same as the example 1, and is characterized in that:
step 2: reducing pre-magnetization
Heating to 80 deg.C, keeping constant temperature and pressure;
the other ways are the same.
In the present example, the conversion rate of converting the iron sesquioxide into the magnetic separation ferroferric oxide in the hydrated calcium iron garnet is 95%, and the separation rate of the magnetic separation iron is 65%.
Example 31
A method for carrying out reduction pre-magnetization on hydrated calcium iron garnet based on an aqueous solution, which is different from the method in example 30 in that:
step 2: reducing pre-magnetization
Reducing for 15h at constant temperature and constant pressure;
the other ways are the same.
In the present example, the conversion rate of converting the iron sesquioxide into the magnetic separation ferroferric oxide in the hydrated calcium iron garnet is 95%, and the separation rate of the magnetic separation iron is 65%.
Example 32
A method for carrying out reduction pre-magnetization on hydrated calcium iron garnet based on an aqueous solution, which is different from the method in example 30 in that:
step 2: reducing pre-magnetization
Reducing for 10 hours at constant temperature and constant pressure;
the other ways are the same.
In the present example, the conversion rate of converting the iron sesquioxide into the magnetic separation ferroferric oxide in the hydrated calcium iron garnet is 95%, and the separation rate of the magnetic separation iron is 65%.
Example 33
A method for carrying out reduction pre-magnetization on hydrated calcium iron garnet based on an aqueous solution, which is the same as example 32 except that:
step 2: reducing pre-magnetization
Reducing for 3 hours at constant temperature and constant pressure;
the other ways are the same.
In the present example, the conversion rate of converting the iron sesquioxide into the magnetic separation ferroferric oxide in the hydrated calcium iron garnet is 95%, and the separation rate of the magnetic separation iron is 65%.
Example 34
A method for carrying out reduction pre-magnetization on hydrated calcium iron garnet based on an aqueous solution, which is the same as the example 1, and is characterized in that:
step 2: reducing pre-magnetization
The pressure of the high-pressure natural gas is 3.0 atm;
the other ways are the same.
In the present embodiment, the conversion rate of converting the iron sesquioxide into the magnetic separation ferroferric oxide in the calcium iron garnet hydrate is 98%, and the separation rate of the magnetic separation iron is 66%.
Example 35
A method for carrying out reduction pre-magnetization on hydrated calcium iron garnet based on an aqueous solution, which is the same as the example 1, and is characterized in that:
step 2: reducing pre-magnetization
The pressure of the high-pressure natural gas is 2.0 atm;
the other ways are the same.
In the present example, the conversion rate of converting the iron sesquioxide into the magnetic separation ferroferric oxide in the calcium iron garnet hydrate is 97%, and the separation rate of the magnetic separation iron is 65%.
Example 36
A method for carrying out reduction pre-magnetization on hydrated calcium iron garnet based on an aqueous solution, which is the same as the example 1, and is characterized in that:
step 2: reducing pre-magnetization
The pressure of the high-pressure natural gas is 1.1 atm;
the other ways are the same.
In the present example, the conversion rate of converting the iron sesquioxide into the magnetic separation ferroferric oxide in the hydrated calcium iron garnet is 95%, and the separation rate of the magnetic separation iron is 65%.
Example 37
A method for carrying out reduction pre-magnetization on hydrated calcium iron garnet based on an aqueous solution, which is the same as the example 1, and is characterized in that:
step 2: reducing pre-magnetization
The pressure of the high-pressure blast furnace gas is 3.0 atm;
the other ways are the same.
In the present example, the conversion rate of converting the iron sesquioxide into the magnetic separation ferroferric oxide in the hydrated calcium iron garnet is 99%, and the separation rate of the magnetic separation iron is 69%.
Example 38
A method for carrying out reduction pre-magnetization on hydrated calcium iron garnet based on an aqueous solution, which is the same as the example 1, and is characterized in that:
step 2: reducing pre-magnetization
The pressure of the high-pressure blast furnace gas is 2.0 atm;
the other ways are the same.
In the present embodiment, the conversion rate of converting the iron sesquioxide into the magnetic separation ferroferric oxide in the calcium iron garnet hydrate is 98%, and the separation rate of the magnetic separation iron is 66%.
Example 39
A method for carrying out reduction pre-magnetization on hydrated calcium iron garnet based on an aqueous solution, which is the same as the example 1, and is characterized in that:
step 2: reducing pre-magnetization
The pressure of the high-pressure blast furnace gas is 1.1 atm;
the other ways are the same.
In the present example, the conversion rate of converting the iron sesquioxide into the magnetic separation ferroferric oxide in the hydrated calcium iron garnet is 97%, and the separation rate of the magnetic separation iron is 66%.
Example 40
A method for carrying out reduction pre-magnetization on hydrated calcium iron garnet based on an aqueous solution, which is the same as the example 1, and is characterized in that:
step 2: reducing pre-magnetization
The pressure of the high-pressure blast furnace gas is 3.0 atm;
the other ways are the same.
In the present example, the conversion rate of converting the iron sesquioxide into the magnetic separation ferroferric oxide is 99%, and the separation rate of the magnetic separation iron is 67%.
EXAMPLE 41
A method for carrying out reduction pre-magnetization on hydrated calcium iron garnet based on an aqueous solution, which is the same as the example 1, and is characterized in that:
step 2: reducing pre-magnetization
The pressure of the high-pressure blast furnace gas is 2.0 atm;
the other ways are the same.
In the present example, the conversion rate of converting the iron sesquioxide into the magnetic separation ferroferric oxide in the hydrated calcium iron garnet is 97%, and the separation rate of the magnetic separation iron is 66%.
Example 42
A method for carrying out reduction pre-magnetization on hydrated calcium iron garnet based on an aqueous solution, which is the same as the example 1, and is characterized in that:
step 2: reducing pre-magnetization
The pressure of the high-pressure blast furnace gas is 1.1 atm;
the other ways are the same.
In the present example, the conversion rate of converting the iron sesquioxide into the magnetic separation ferroferric oxide in the hydrated calcium iron garnet is 95%, and the separation rate of the magnetic separation iron is 65%.
Example 43
A method for carrying out reduction pre-magnetization on hydrated calcium iron garnet based on an aqueous solution, which is the same as the example 1, and is characterized in that:
step 2: reducing pre-magnetization
High pressure H2The pressure of (2) is 3.0 atm;
the other ways are the same.
In the present embodiment, the conversion rate of converting the iron sesquioxide into the magnetic separation ferroferric oxide in the hydrated calcium iron garnet is 99%, and the separation rate of the magnetic separation iron is 68%.
Example 45
A method for carrying out reduction pre-magnetization on hydrated calcium iron garnet based on an aqueous solution, which is the same as the example 1, and is characterized in that:
step 2: reducing pre-magnetization
High pressure H2The pressure of (2.0 atm);
the other ways are the same.
In the present embodiment, the conversion rate of converting the iron sesquioxide into the magnetic separation ferroferric oxide in the calcium iron garnet hydrate is 98%, and the separation rate of the magnetic separation iron is 66%.
Example 45
A method for carrying out reduction pre-magnetization on hydrated calcium iron garnet based on an aqueous solution, which is the same as the example 1, and is characterized in that:
step 2: reducing pre-magnetization
High pressure H2The pressure of (1.1 atm);
the other ways are the same.
In the present example, the conversion rate of converting the iron sesquioxide into the magnetic separation ferroferric oxide in the hydrated calcium iron garnet is 97%, and the separation rate of the magnetic separation iron is 66%.
Claims (9)
1. A method for carrying out reduction pre-magnetization on hydrated calcium iron garnet based on aqueous solution is characterized by comprising the following steps:
step 1: mixing material
Mixing hydrated calcium iron garnet with water to obtain a mixed solution; pouring the mixed solution into a high-temperature high-pressure reaction kettle, and sealing;
the hydrated calcium iron garnet is solid waste of red mud high-pressure hydration treatment, and the chemical formula of the hydrated calcium iron garnet is as follows: 3 CaO. Fe2O3·nSiO2·mH2O, wherein n =1-2, m is a positive integer, and m is more than or equal to 1; particle size<20 μm, by mass, of Na2O：SiO2<0.002；
Step 2: reducing pre-magnetization
Introducing inert gas into the high-temperature high-pressure reaction kettle to evacuate air, introducing high-pressure reducing gas into the mixed solution to reach a pressure P, heating to 80-260 ℃, and carrying out constant-temperature and constant-pressure reduction for pre-magnetization to obtain pre-magnetized hydrated calcium iron garnet; wherein the pressure P is 1.0< P is less than or equal to 3.0 atm; the pre-magnetization time is more than or equal to 30 min;
and step 3: reducing blood pressure
After reduction and pre-magnetization are finished, reducing the pressure of the high-temperature high-pressure reaction kettle to normal pressure, introducing inert gas into the high-temperature high-pressure reaction kettle, and diluting until the content of the reducing gas is below the safe content value in the air;
and 4, step 4: separation of
And (3) carrying out magnetic separation on the obtained pre-magnetized hydrated calcium iron garnet, wherein the iron separation rate is 65-70%.
2. The method for carrying out reductive pre-magnetization on calcium iron garnet hydrate based on aqueous solution according to claim 1, characterized in that, in the step 1, the ratio by volume of the calcium iron garnet hydrate: the water is less than or equal to 2: 3.
3. The method for reducing and pre-magnetizing hydrated calcium iron garnet based on aqueous solution as claimed in claim 1, wherein in the step 2, the reducing gas is a reducing gas which can reduce the hydrated calcium iron garnet at normal temperature and normal pressure according to thermodynamic calculation.
4. The method for reducing and pre-magnetizing hydrated calcium iron garnet according to claim 3, wherein the reducing gas is CO, natural gas, blast furnace gas, H2One or more of them.
5. The method for reductive pre-magnetization of hydrogecite based on aqueous solution according to claim 4, characterized in that the natural gas has CH as main component4The volume purity is more than or equal to 98 percent; the main components of the blast furnace gas are CO and H2CO and H2The volume purity of the product is more than or equal to 98 percent; the volume purity of the CO is more than or equal to 98 percent; said H2The volume purity of the product is more than or equal to 98 percent.
6. The method for carrying out reduction and pre-magnetization on hydrated calcium iron garnet based on aqueous solution according to claim 1, wherein in the step 2, the conversion rate of iron oxide in the pre-magnetized hydrated calcium iron garnet into ferroferric oxide is not less than 95%.
7. The method for carrying out reduction and pre-magnetization on calcium iron garnet hydrate based on an aqueous solution according to claim 1, wherein the pre-magnetization time in the step 2 is 3-20 h.
8. The method for reductive pre-magnetization of hydrated calcium iron garnet based on aqueous solution according to claim 1, characterized in that in step 3, the inert gas is argon and/or nitrogen.
9. The method for reductive pre-magnetization of hydrated calcium iron garnet based on aqueous solution as claimed in claim 1, characterized in that in step 3, the reduction gas to below the safe content value in air is determined according to the explosion limit of combustible gas in air.
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