CN113149469B - Method for producing lime by combining waste coal with sintering plant - Google Patents
Method for producing lime by combining waste coal with sintering plant Download PDFInfo
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- CN113149469B CN113149469B CN202110534319.2A CN202110534319A CN113149469B CN 113149469 B CN113149469 B CN 113149469B CN 202110534319 A CN202110534319 A CN 202110534319A CN 113149469 B CN113149469 B CN 113149469B
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- waste coal
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- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B2/00—Lime, magnesia or dolomite
- C04B2/10—Preheating, burning calcining or cooling
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- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B2/00—Lime, magnesia or dolomite
- C04B2/02—Lime
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B2/00—Lime, magnesia or dolomite
- C04B2/10—Preheating, burning calcining or cooling
- C04B2/104—Ingredients added before or during the burning process
Abstract
The invention discloses a method for producing lime by combining waste coal with a sintering plant, and relates to the technical field of building materials. When the lime is produced from the waste coal, the waste coal is pretreated firstly, and then the lime is produced; during pretreatment, performing two-stage microwave heating on the waste coal, soaking the waste coal in a sodium hydroxide solution during the first-stage microwave heating, stirring and introducing mixed gas of water vapor and carbon dioxide after heating, changing the temperature during the second-stage microwave heating, stopping heating after evaporating the solution to dryness, and performing ball milling to obtain the pretreated waste coal; and adding calcium carbonate into the pretreated waste coal to form a mixed material, and sintering for three times to prepare lime. The lime produced by the method for producing lime by combining waste coal with a sintering plant has no impurities, and when the lime is used as a building material, no free calcium oxide influences the stability of the material, so that the safety and the strength of the material can be greatly improved.
Description
Technical Field
The invention relates to the technical field of building materials, in particular to a method for producing lime by combining waste coal with a sintering plant.
Background
Lime is an air-hardening inorganic gelling material with calcium oxide as a main component. The lime is a product with high calcium carbonate content such as limestone, dolomite, chalk, shells and the like, and is calcined at 900-1100 ℃. Lime was the earliest gelling material used by humans. The lime has wide application range in civil engineering and can also be used in medicine in China. Therefore, ancient streams have passed poems, namely swampus songs, which take lime as the subject.
If the waste coal can be used for producing lime, the use of the raw materials can be reduced, and the effect of waste utilization can be achieved. And lime with higher activity can be prepared, and when the lime is used as a building material, free calcium oxide does not influence the stability of the material, so that the safety and the strength of the material are greatly improved.
Disclosure of Invention
The invention aims to provide a method for producing lime by combining waste coal with a sintering plant so as to solve the problems in the background technology.
In order to solve the above technical problem, a first aspect of the present invention provides the following technical solutions: a method for producing lime by combining waste coal with a sintering plant is characterized by comprising the following process flows:
and (4) preprocessing and sintering.
Preferably, the method comprises the following specific steps:
(1) soaking the waste coal in a sodium hydroxide solution with the mass fraction of 20-50%, carrying out first microwave heating, stirring after heating, and introducing mixed gas of water vapor and carbon dioxide;
(2) directly carrying out secondary microwave heating on the waste coal subjected to the primary microwave heating, stopping heating after the solvent is evaporated to dryness, and naturally cooling to room temperature;
(3) placing the cooled waste coal in a ball mill for ball milling to prepare pretreated waste coal;
(4) adding calcium carbonate into the pretreated waste coal to form a mixed material, performing primary sintering, and performing secondary sintering when no gas escapes from the system;
(5) keeping the temperature unchanged, sintering the mixed material subjected to the second sintering for the third time, and naturally cooling to room temperature to obtain a finished product.
Preferably, in the step (1): the mass ratio of the waste coal to the sodium hydroxide solution is 1: 10; the volume ratio of the water vapor to the carbon dioxide is 1: 1-1: 2, the stirring speed is 500-800 rpm.
Preferably, in the step (1): the first microwave heating power is 300-800W, the frequency is 1.0-1.5 GHz, the temperature is 90-120 ℃, and the time is 10-20 min.
Preferably, in the step (2): the second microwave heating power is 2000-3000W, the frequency is 2-3 GHz, and the temperature is 1400-1800 ℃.
Preferably, in the step (3): the ball milling time is 10-15 min.
Preferably, in the step (4): the mass ratio of the pretreated waste coal to the calcium carbonate is 1: 1-1: 2; and (3) carrying out gradient temperature rise during the first sintering, keeping the temperature for 1-2 hours when the temperature rises to 200-300 ℃ every time, and raising the temperature to 1500-1800 ℃.
Preferably, in the step (5): and ventilating during the third sintering, wherein the ventilating rate is 5-10L/h.
In a second aspect of the invention, a method for producing lime by combining waste coal with a sintering plant is characterized in that the lime produced by combining the waste coal with the method for producing lime by combining the sintering plant comprises the following raw materials in parts by weight: 20-40 parts of waste coal, 10-15 parts of sodium hydroxide and 20-80 parts of calcium carbonate; the content of calcium oxide in the waste coal is 5-10%.
Compared with the prior art, the invention has the following beneficial effects:
when lime is produced from waste coal, the waste coal is pretreated firstly, and then the lime is produced; during pretreatment, performing two-stage microwave heating on the waste coal, soaking the waste coal in a sodium hydroxide solution during the first-stage microwave heating, stirring and introducing mixed gas of water vapor and carbon dioxide after heating, changing the temperature during the second-stage microwave heating, stopping heating after evaporating the solution to dryness, and performing ball milling to obtain the pretreated waste coal; during the first stage of microwave heating, the waste coal is soaked in a sodium hydroxide solution, calcium oxide in the waste coal is converted into calcium hydroxide, the calcium hydroxide is stirred and introduced with mixed gas of water vapor and carbon dioxide after heating, and tar remained in the waste coal is volatilized or dissolved in the solution along with the escape of the gas, so that most of impurities in the waste coal can be removed; changing the temperature during the second stage of microwave heating to ensure that calcium oxide is regenerated from calcium hydroxide, and evaporating tar in the solvent to dryness while calcium silicate is generated from the calcium hydroxide and the silicon dioxide; the thermal stress of the mineral phase in the waste coal after twice microwave heating is increased, the grindability of the waste coal is enhanced, and the ball milling energy is reduced; the two-stage microwave heating pretreatment mode not only completely removes impurities in the waste coal, but also enables the components of the pretreated waste coal to be calcium silicate, aluminum oxide, iron oxide and magnesium oxide, can be directly used for preparing lime and reduces the ball milling energy.
Adding calcium carbonate into the pretreated waste coal to form a mixed material, and sintering for three times to prepare lime; the first sintering is carried out with slow gradient temperature rise, when calcium carbonate is decomposed into calcium oxide, lattice transition can occur, the rhombohedral lattice of the calcium carbonate is changed into the cubic lattice of the calcium oxide, the crystallization is promoted to grow rapidly by slowing down the temperature, most of calcium oxide crystals are irregular along with the escape of carbon dioxide, the irregular shape is combined with calcium silicate, aluminum oxide, iron oxide and magnesium oxide in the pretreated waste coal to form combined calcium oxide, and meanwhile, a porous structure is also formed, so that the activity degree of the prepared lime is higher, and the second sintering is carried out when no gas escapes from the system; stirring under sealed condition during the second sintering, wherein the residual carbon dioxide in the mixed material escapes through stirring and temperature rise, so that the pressure during sintering is increased, a small part of incompletely-developed calcium oxide crystals have internal defects, and the internal defects collapse under the action of pressure and are recombined on the surface of the combined calcium oxide; the third sintering is carried out by slow ventilation, so that the calcium oxide blocking the pores of the combined calcium oxide flies out, the activity of the lime is ensured, the raw materials are utilized to the maximum extent, and the free calcium oxide is removed; the lime prepared by three times of sintering has higher activity, and when the lime is used as a building material, no free calcium oxide influences the stability of the material, and the safety and the strength of the material can be greatly improved.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
To illustrate the process of the present invention more clearly, the following examples are provided to illustrate the process of the present invention, and the test methods for each index of lime produced in the following examples are as follows:
purity: the lime produced in examples 1 and 2 and comparative example 1 was dissolved in water, titrated with acid, and the content of available calcium oxide was measured to calculate the purity of lime.
Lime activity: and (3) measuring the activity degree of lime by adopting an acid-base titration method, wherein the activity degree is more than 320mL, and the active lime is obtained.
Example 1
The lime produced by the method for producing lime by combining waste coal with a sintering plant mainly comprises the following components in parts by weight:
20 parts of waste coal, 10 parts of sodium hydroxide and 20 parts of calcium carbonate; the content of calcium oxide in the waste coal is 5-10%.
A method for producing lime by combining waste coal with a sintering plant comprises the following steps:
(1) soaking the waste coal in a sodium hydroxide solution with the mass fraction of 20%, wherein the mass ratio of the waste coal to the sodium hydroxide solution is 1: 10, carrying out first microwave heating with the power of 300W, the frequency of 1.0GHz, the temperature of 90 ℃ and the time of 10min, stirring after heating, and introducing mixed gas of water vapor and carbon dioxide, wherein the volume ratio of the water vapor to the carbon dioxide is 1: 1, stirring speed is 500 rpm;
(2) directly carrying out secondary microwave heating on the waste coal subjected to the primary microwave heating, wherein the power is 2000W, the frequency is 2GHz, the temperature is 1400 ℃, stopping heating after the solvent is evaporated to dryness, and naturally cooling to room temperature;
(3) placing the cooled waste coal into a ball mill for ball milling for 10min to prepare pretreated waste coal;
(4) adding calcium carbonate into the pretreated waste coal to form a mixed material, wherein the mass ratio of the pretreated waste coal to the calcium carbonate is 1: 1, carrying out primary sintering, raising the temperature to 1500 ℃, keeping the temperature at 250 ℃ per liter for 1h, carrying out secondary sintering when no gas escapes from a system after the temperature reaches 1500 ℃, and stirring the secondary sintering under a sealed condition at the stirring speed of 1000 rpm;
(5) keeping the temperature unchanged, sintering the mixed material subjected to the second sintering for the third time, performing ventilation sintering at the ventilation rate of 5L/h, and naturally cooling to room temperature to obtain a finished product.
Example 2
The lime produced by the method for producing lime by combining waste coal with a sintering plant mainly comprises the following components in parts by weight:
20 parts of waste coal, 10 parts of sodium hydroxide and 20 parts of calcium carbonate; the content of calcium oxide in the waste coal is 5-10%.
A method for producing lime by combining waste coal with a sintering plant comprises the following steps:
(1) soaking waste coal in a sodium hydroxide solution with the mass fraction of 50%, wherein the mass ratio of the waste coal to the sodium hydroxide solution is 1: 10, performing first microwave heating with the power of 800W, the frequency of 1.5GHz, the temperature of 120 ℃ and the time of 20min, stirring after heating, and introducing mixed gas of water vapor and carbon dioxide, wherein the volume ratio of the water vapor to the carbon dioxide is 1: 2, the stirring speed is 800 rpm;
(2) directly carrying out secondary microwave heating on the waste coal subjected to the primary microwave heating, wherein the power is 3000W, the frequency is 3GHz, the temperature is 1800 ℃, stopping heating after the solvent is evaporated to dryness, and naturally cooling to room temperature;
(3) placing the cooled waste coal into a ball mill for ball milling for 15min to prepare pretreated waste coal;
(4) adding calcium carbonate into the pretreated waste coal to form a mixed material, wherein the mass ratio of the pretreated waste coal to the calcium carbonate is 1: 2, carrying out primary sintering, raising the temperature to 1800 ℃, carrying out heat preservation for 2 hours when the temperature is raised to 300 ℃, carrying out secondary sintering when no gas escapes from the system after the temperature is raised to 1800 ℃, and carrying out secondary sintering under the sealed condition with the stirring speed of 1500 rpm;
(5) and keeping the temperature unchanged, sintering the mixed material subjected to the second sintering for the third time, performing ventilation sintering at the ventilation rate of 10L/h, and naturally cooling to room temperature to obtain a finished product.
Comparative example 1
The lime produced by the method for producing lime by combining waste coal with a sintering plant mainly comprises the following components in parts by weight:
20 parts of waste coal and 20 parts of calcium carbonate; the content of calcium oxide in the waste coal is 5-10%.
A method for producing lime by combining waste coal with a sintering plant comprises the following steps:
(1) adding calcium carbonate into waste coal to form a mixed material, wherein the mass ratio of the waste coal to the calcium carbonate is 1: 1, carrying out primary sintering, raising the temperature to 1500 ℃, keeping the temperature at 250 ℃ per liter for 1h, carrying out secondary sintering when no gas escapes from a system after the temperature reaches 1500 ℃, and stirring the secondary sintering under a sealed condition at the stirring speed of 1000 rpm;
(2) and (5) keeping the temperature unchanged, sintering the mixed material subjected to the second sintering for the third time, performing ventilation sintering at the ventilation rate of 5L/h, and naturally cooling to room temperature to obtain a finished product.
Comparative example 2
The lime produced by the method for producing lime by combining waste coal with a sintering plant mainly comprises the following components in parts by weight:
20 parts of waste coal, 10 parts of sodium hydroxide and 20 parts of calcium carbonate; the content of calcium oxide in the waste coal is 5-10%.
A method for producing lime by combining waste coal with a sintering plant comprises the following steps:
(1) soaking the waste coal in a sodium hydroxide solution with the mass fraction of 20%, wherein the mass ratio of the waste coal to the sodium hydroxide solution is 1: 10, carrying out first microwave heating with the power of 300W, the frequency of 1.0GHz, the temperature of 90 ℃ and the time of 10min, stirring after heating, and introducing mixed gas of water vapor and carbon dioxide, wherein the volume ratio of the water vapor to the carbon dioxide is 1: 1, stirring speed is 500 rpm;
(2) directly carrying out secondary microwave heating on the waste coal subjected to the primary microwave heating, wherein the power is 2000W, the frequency is 2GHz, the temperature is 1400 ℃, stopping heating after the solvent is evaporated to dryness, and naturally cooling to room temperature;
(3) placing the cooled waste coal into a ball mill for ball milling for 10min to prepare pretreated waste coal;
(4) adding calcium carbonate into the pretreated waste coal to form a mixed material, wherein the mass ratio of the pretreated waste coal to the calcium carbonate is 1: 1, sintering at 1500 ℃ for 10h, and naturally cooling to room temperature after sintering to obtain a finished product.
Effect example 1
Table 1 below shows the results of the analysis of lime purity using the present invention to test examples 1 and 2 and comparative example 1.
TABLE 1
| Purity (%) | |
| Example 1 | 92.1 |
| Example 2 | 91.9 |
| Comparative example 1 | 70.6 |
By comparing the purity of the lime in the examples 1 and 2 with that in the comparative example 1, it can be obviously found that most impurities in the waste coal can be removed by immersing the lime in sodium hydroxide and performing the pretreatment of ball milling after two times of microwave heating in the examples 1 and 2, so that the purity of the lime produced by the waste coal combined with the method for producing lime in a sintering plant is higher.
Effect example 2
Table 2 below shows the results of the analysis of the lime activity using the present invention for examples 1 and 2 and comparative example 2.
TABLE 2
| Activity (mL) | |
| Example 1 | 394 |
| Example 2 | 392 |
| Comparative example 1 | 300 |
By comparing the lime activity of examples 1 and 2 with that of comparative example 2, it is obvious that examples 1 and 2 have higher purity of lime produced by the method of producing lime by combining waste coal with a sintering plant through three times of sintering and combining sealing and ventilation conversion.
Finally, it should be noted that: although the present invention has been described in detail with reference to the foregoing embodiments, it will be apparent to those skilled in the art that changes may be made in the embodiments and/or equivalents thereof without departing from the spirit and scope of the invention. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (9)
1. A method for producing lime by combining waste coal with a sintering plant is characterized by comprising the following process flows: preprocessing and sintering;
the method for producing lime by combining waste coal with a sintering plant comprises the following specific steps:
(1) soaking the waste coal in a sodium hydroxide solution with the mass fraction of 20-50%, carrying out first microwave heating, stirring after heating, and introducing mixed gas of water vapor and carbon dioxide;
(2) directly carrying out secondary microwave heating on the waste coal subjected to the primary microwave heating, stopping heating after the solvent is evaporated to dryness, and naturally cooling to room temperature;
(3) placing the cooled waste coal in a ball mill for ball milling to prepare pretreated waste coal;
(4) adding calcium carbonate into the pretreated waste coal to form a mixed material, performing primary sintering, and performing secondary sintering when no gas escapes from the system;
(5) keeping the temperature unchanged, sintering the mixed material subjected to the second sintering for the third time, and naturally cooling to room temperature to obtain a finished product.
2. The method for producing lime by using waste coal combined with a sintering plant according to claim 1, wherein in the step (1): the mass ratio of the waste coal to the sodium hydroxide solution is 1: 10; the volume ratio of the water vapor to the carbon dioxide is 1: 1-1: 2, the stirring speed is 500-800 rpm.
3. The method for producing lime by using waste coal combined with a sintering plant according to claim 1, wherein in the step (1): the first microwave heating power is 300-800W, the frequency is 1.0-1.5 GHz, the temperature is 90-120 ℃, and the time is 10-20 min.
4. The method for producing lime by using waste coal combined with a sintering plant according to claim 1, wherein in the step (2): the second microwave heating power is 2000-3000W, the frequency is 2-3 GHz, and the temperature is 1400-1800 ℃.
5. The method for producing lime by using waste coal combined with a sintering plant according to claim 1, wherein in the step (3): the ball milling time is 10-15 min.
6. The method for producing lime by using waste coal combined with a sintering plant according to claim 1, wherein in the step (4): the mass ratio of the pretreated waste coal to the calcium carbonate is 1: 1-1: 2; and (3) carrying out gradient temperature rise during the first sintering, keeping the temperature for 1-2 hours every time the temperature rises to 200-300 ℃, and raising the temperature to 1500-1800 ℃.
7. The method for producing lime by using waste coal combined with a sintering plant according to claim 1, wherein in the step (4): and stirring the mixture under a sealed condition during the second sintering, wherein the stirring speed is 1000-1500 rpm.
8. The method for producing lime by using waste coal combined with a sintering plant according to claim 1, wherein in the step (5): and ventilating during the third sintering, wherein the ventilating rate is 5-10L/h.
9. The method for producing lime by combining waste coal and a sintering plant according to claim 1, wherein the lime produced by combining the waste coal and the method for producing lime by combining the waste coal and the sintering plant comprises the following raw materials in parts by weight: 20-40 parts of waste coal, 10-15 parts of sodium hydroxide and 20-80 parts of calcium carbonate; the content of calcium oxide in the waste coal is 5-10%.
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| CN108264247B (en) * | 2018-02-10 | 2020-10-30 | 广西华洋矿源材料有限公司 | Production process of active lime |
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