CN113051847B - Evaluation method and optimization method for thermal stability of blast furnace slag - Google Patents
Evaluation method and optimization method for thermal stability of blast furnace slag Download PDFInfo
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- 239000002893 slag Substances 0.000 title claims abstract description 208
- 238000000034 method Methods 0.000 title claims abstract description 47
- 238000005457 optimization Methods 0.000 title claims description 7
- 238000011156 evaluation Methods 0.000 title description 14
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- 239000000126 substance Substances 0.000 claims description 25
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- 230000008025 crystallization Effects 0.000 claims description 10
- 229910018072 Al 2 O 3 Inorganic materials 0.000 claims description 9
- 230000007704 transition Effects 0.000 claims description 9
- 229910004298 SiO 2 Inorganic materials 0.000 claims description 6
- SNAAJJQQZSMGQD-UHFFFAOYSA-N aluminum magnesium Chemical compound [Mg].[Al] SNAAJJQQZSMGQD-UHFFFAOYSA-N 0.000 claims description 5
- 239000013078 crystal Substances 0.000 claims description 3
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- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 claims 1
- 229910052782 aluminium Inorganic materials 0.000 claims 1
- 229910052749 magnesium Inorganic materials 0.000 claims 1
- 239000011777 magnesium Substances 0.000 claims 1
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 abstract description 12
- 229910052742 iron Inorganic materials 0.000 abstract description 6
- 238000013021 overheating Methods 0.000 abstract description 4
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- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06F—ELECTRIC DIGITAL DATA PROCESSING
- G06F30/00—Computer-aided design [CAD]
- G06F30/20—Design optimisation, verification or simulation
- G06F30/28—Design optimisation, verification or simulation using fluid dynamics, e.g. using Navier-Stokes equations or computational fluid dynamics [CFD]
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- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06F—ELECTRIC DIGITAL DATA PROCESSING
- G06F2113/00—Details relating to the application field
- G06F2113/08—Fluids
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- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06F—ELECTRIC DIGITAL DATA PROCESSING
- G06F2119/00—Details relating to the type or aim of the analysis or the optimisation
- G06F2119/08—Thermal analysis or thermal optimisation
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- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06F—ELECTRIC DIGITAL DATA PROCESSING
- G06F2119/00—Details relating to the type or aim of the analysis or the optimisation
- G06F2119/14—Force analysis or force optimisation, e.g. static or dynamic forces
Abstract
A method for evaluating and optimizing the thermal stability of blast furnace slag relates to the technical field of iron making, and comprises the following steps: s1: obtaining the quality and production temperature of each component in the slag; calculating a first enthalpy change value of the slag heating stage based on thermodynamic software; calculating a second enthalpy change value of the slag heating stage based on the thermodynamic reaction formula; s2: taking the average value of the first enthalpy change value and the second enthalpy change value as an actual enthalpy change value; s3: adjusting the alkalinity of slag, and repeatedly executing the steps S1-S2 to obtain a plurality of groups of actual enthalpy change values of slag with different alkalinity; s4: based on the second law of thermodynamics, taking the average value of the actual enthalpy change values of a plurality of groups of slag with different alkalinity as the total heat required by the slag heating stage; s5: and (3) inputting total heat into the slag, and calculating the change rate of the viscosity of the slag with the alkalinity of the slag after the total heat is input. The method can realize quantitative research on the thermal stability of the blast furnace slag, and avoid the problems of overheating of the blast furnace slag, insufficient furnace temperature and the like.
Description
Technical Field
The invention relates to the technical field of iron making, in particular to an evaluation method and an optimization method for the thermal stability of blast furnace slag.
Background
The reasonable utilization of energy is the direction of exploring and developing in all industries, and along with the continuous development of economy and society, the demand for energy is increased. The demand for energy in the ferrous metallurgy industry as a support industry is particularly great, and blast furnace iron making is one of the most energy consuming parts of the whole industry. In the blast furnace ironmaking process, a considerable part of heat is not reasonably utilized, and in order to ensure the physicochemical reaction temperature required by smelting, slag is often overheated, which has adverse effect on the service life of blast furnace equipment. Therefore, controlling reasonable heat in slag is important to energy conservation and emission reduction in the iron and steel industry and improving the energy utilization efficiency. To achieve reasonable control of the heat in the slag, a precondition is to define the thermal stability of the slag.
The thermal stability of slag is the capability of the slag to resist heat fluctuation, and when the input heat in smelting equipment changes, the slag with higher thermal stability can only generate smaller temperature change under the condition of fluctuation of the input heat, thereby avoiding adverse effects on melt fluidity and slag-gold reaction in the smelting process.
In recent years, with the continuous enlargement of blast furnaces and the change of the ingredients of furnace charge materials in China, the requirements on the thermal stability of slag are higher and higher. However, due to the reduction in the number of high quality ores of high grade and the increase in price costs, imported ores and low grade ores are the choice for large enterprises. But with too much Al being charged into the furnace 2 O 3 The composition such as MgO and the like deteriorates the thermal stability of the slag, and excessive Al is present in the slag 2 O 3 When the slag is used, a high-melting-point compound with strong crystallization capacity is generated, so that the enthalpy change of the slag is increased, the fluidity is deteriorated, and the metallurgical performance is deteriorated; when the MgO content is too high, high-melting-point substances are formed, so that the viscosity of slag is increased, the fluidity is deteriorated, the amount of sintering molten agent is increased, the coke ratio is increased, and the principle of economic ironmaking is not met; furthermore, it is possible to provide a device for the treatment of a disease. Heat during blast furnace damping down and re-blowingThe fluctuation is obvious, and the thermal stability of the slag can also obviously influence smelting. The slag is taken as one of main byproducts of the blast furnace, and the related high-temperature materialization process of the slag in the smelting process has been studied more, but the heat stability of the slag is more closely compared with the energy-saving emission-reduction and high-efficiency production, and a system evaluation method for the heat stability is not formed at present.
In practical production, the adding amount of the blast furnace fuel is a link which is easy to control. When the furnace slag component changes due to the fluctuation of the furnace burden ore component, if the thermal stability of the furnace slag can be clarified, the heat of the furnace entering can be timely adjusted, so that the furnace slag starts from the thermal stability of the furnace slag, a reasonable theoretical heat value is obtained by matching, the energy utilization rate is improved, and the fluctuation of the furnace temperature of the blast furnace is slowed down. Blind guessing that the amount of fuel fed into the furnace can cause the increase of consumption of coke and coal dust, thereby causing resource waste and economic cost increase, and being not beneficial to the adjustment of the fluidity of slag in the blast furnace and influencing metallurgical performance. Therefore, the reasonable evaluation method for the thermal stability of the slag is explored, the buffer capacity of the slag and the heat utilization efficiency of the slag can be improved when the furnace condition of the blast furnace fluctuates, and slag components in the furnace can be pertinently regulated according to the evaluation result, so that the slag in the furnace tends to be in a state with better thermal stability, and the method has important significance for efficient, stable and smooth operation of blast furnace smelting in China.
The invention is used for the related calculation of the thermal stability of the blast furnace slag through a reaction balance calculation module in thermodynamic software. And then, reducing software errors through mathematical integral calculation to obtain a thermal stability evaluation image very close to an actual result, and guiding actual production.
Compared with the traditional blast furnace thermal fluctuation experience estimation method, the method can realize accurate measurement of furnace overheating or insufficient heat through evaluation of the thermal stability of the furnace slag, can be timely and quickly suitable for large-scale production, and more importantly, the evaluation thought is constructed by combining a software calculation result and a thermodynamic equation result, so that systematic errors are offset greatly, the industrial application prospect is wide, and the method has important social benefit for finally solving the irregular problem of the thermal fluctuation of the blast furnace slag.
Disclosure of Invention
The invention provides a method for evaluating the thermal stability of blast furnace slag. The method fully utilizes a reaction balance calculation module and mathematical integral calculation of metallurgical thermodynamic software to obtain a thermal stability numerical image very close to an actual result, realizes quantitative research on the thermal stability of the blast furnace slag, further carries out accurate and reliable production guidance, and effectively avoids the problems of overheating or insufficient furnace temperature of the blast furnace slag and the like.
According to a first aspect of the present invention, there is provided a method for evaluating the thermal stability of blast furnace slag, the method comprising the steps of:
s1: obtaining the quality and production temperature of each component in the slag;
s2: calculating a first enthalpy change value of the slag heating stage based on thermodynamic software;
calculating a second enthalpy change value of the slag heating stage based on the thermodynamic reaction formula;
s3: taking the average value of the first enthalpy change value and the second enthalpy change value as an actual enthalpy change value;
s4: regulating the alkalinity of slag to obtain a plurality of groups of slag with different alkalinity, and repeatedly executing the steps S1-S3 to obtain the actual enthalpy change values of the plurality of groups of slag with different alkalinity;
s5: based on the second law of thermodynamics, taking the average value of the actual enthalpy change values of a plurality of groups of slag with different alkalinity as the total heat required by the slag heating stage;
s6: inputting total heat into the slag, and calculating the change rate of the slag viscosity after the total heat is input along with the change of the slag alkalinity;
wherein, the larger the absolute value of the viscosity change rate of the slag is, the worse the thermal stability of the slag is.
Further, the viscosity change rate is calculated as follows:
wherein VCR is the slag viscosity change rate, eta j And j is a positive integer for slag viscosity.
Further, the production temperature ranges from 1200 ℃ to 1600 ℃.
Further, the first enthalpy change value is calculated as follows:
the mass of each component in the slag is input into thermodynamic calculation software, and the enthalpy value H of the slag at 298K temperature is calculated respectively 298 And the enthalpy value H of the slag at the production temperature T t The first enthalpy change value delta H A ＝H t -H 298 。
Further, the second enthalpy change value is calculated by:
and inquiring an inorganic crystal structure database according to the quality and the production temperature of each component in the slag to obtain the specific heat capacity of the slag, and calculating a second enthalpy change value by using the specific heat capacity of the slag.
Further, the calculation mode of the specific heat capacity of the slag is as follows:
C pCaO ＝1.048-2.046×10 4 T -2 -2.388T -1/2 +1.836×10 6 T -3 (T＝298～2845K)
C pMgO ＝1.516-1.541×10 4 T -2 -7.349T -1/2 +1.45×10 4 T -3 (T＝298～3098K)
wherein C is pi Is the specific heat capacity of a substance i in the slag, wherein the substance i comprises CaO and SiO 2 、MgO、Al 2 O 3 Any one of them; m is m i Mass of substance i; t is the actual calculated temperature;
further, the second enthalpy change value is calculated as follows:
ΔH B ＝∑m i ΔH i
ΔH i is the enthalpy change value of the substance i in the slag; delta tr H i Is the enthalpy of crystallization transition of substance i in the slag; delta l s H i Is the solid-liquid transition enthalpy of the substance i; t (T) tr Is the transition temperature; t (T) M Is the slag melting temperature; t is the actual calculated temperature; ΔH B Is a second enthalpy change value; m is m i Mass of substance i; s is solid phase crystallization; l is liquid phase crystallization.
Further, the evaluation method further comprises the steps of linearly inputting the total heat into the slag, and calculating a slag temperature change rate in the total heat input process, wherein the larger the absolute value of the slag temperature change rate is, the worse the thermal stability of the slag is.
According to a second aspect of the present invention, there is provided a blast furnace slag optimizing method, the method comprising:
and (3) finely adjusting the slag component for a plurality of times, repeating the heat stability evaluation method, and selecting the slag component with the minimum absolute value of the slag viscosity change rate as the optimal slag.
Further, the slag component fine adjustment comprises one or more of component fine adjustment, alkalinity fine adjustment and magnesium-aluminum ratio fine adjustment;
wherein the fine-tuning of the components comprises adjusting the components of the slag;
the fine adjustment range of the alkalinity fine adjustment is 0.7-1.4;
the fine tuning range of the magnesium-aluminum ratio fine tuning is 0.3-1.0.
Compared with the prior art, the blast furnace slag heat stability evaluation method provided by the invention has the following advantages:
the hysteresis exists in the prediction of the furnace temperature of a plurality of blast furnaces in China, the charging quantity of fuel is not matched with the composition change of furnace charge in time, so that the problem of insufficient slag-to-metal reaction caused by overheating of slag or insufficient temperature easily occurs in production, and the high importance is placed on how to reasonably distribute smelting energy sources. The heat stability of the slag is judged by experience, so that not only is a unified measurement standard difficult to form, but also the wide popularization is difficult. The evaluation method is based on the heat absorption and release behavior of a melt in metallurgy, firstly, the quenched slag taken out from a furnace is made into powder, then the components of a sample are measured, then the enthalpy data and the viscosity data of the slag with the components under a certain temperature step are calculated by using metallurgical thermodynamic software, and finally, the heat stability parameter of the slag is obtained through integral calculation and mapping.
According to the invention, on the basis of grasping slag components, the temperature and viscosity of the slag under the condition of fixed heat are solved, and the obtained viscosity data are analyzed and plotted to obtain parameters for the thermal stability of the slag. The method has the advantages of simple operation, easy grasp and wide application range, and can rapidly evaluate the heat stability of different slag. The method not only can realize reasonable energy distribution of the blast furnace slag, but also can give optimization opinion from the angles of temperature and components, solves the problem that the fluctuation of slag heat in the blast furnace is difficult to predict in the blast furnace ironmaking process, and has wide industrial application prospect.
Drawings
The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the invention.
In the drawings:
FIG. 1 is a schematic flow chart of a method for evaluating the thermal stability of blast furnace slag according to the present invention;
FIG. 2 is a graph showing the temperature fluctuation with heat according to the embodiment of the invention;
FIG. 3 is a graphical representation of the thermal stability of an embodiment of the present invention.
Detailed Description
Reference will now be made in detail to exemplary embodiments, examples of which are illustrated in the accompanying drawings. When the following description refers to the accompanying drawings, the same numbers in different drawings refer to the same or similar elements, unless otherwise indicated. The implementations described in the following exemplary examples do not represent all implementations consistent with the invention. Rather, they are merely examples of apparatus and methods consistent with aspects of the invention as detailed in the accompanying claims.
The terms first, second and the like in the description and in the claims, are used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order. It is to be understood that the data so used may be interchanged where appropriate such that the embodiments of the invention described herein may be implemented, for example, in sequences other than those illustrated or otherwise described herein. Furthermore, the terms "comprises," "comprising," and "having," and any variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, system, article, or apparatus that comprises a list of steps or elements is not necessarily limited to those steps or elements expressly listed but may include other steps or elements not expressly listed or inherent to such process, method, article, or apparatus.
A plurality, including two or more.
And/or, it should be understood that for the term "and/or" as used in this disclosure, it is merely one type of association relationship describing the associated object, meaning that there may be three relationships. For example, a and/or B may represent: a exists alone, A and B exist together, and B exists alone.
As shown in fig. 1, the method is based on the second law of thermodynamics, provides a concept of digitizing the thermal stability of the specific blast furnace slag, fully utilizes metallurgical thermodynamic databases and thermodynamic calculation, derives a numerical image capable of representing the thermal stability of the slag by taking chemical components and actual temperature of the blast furnace slag as parameters, obtains an optimized countermeasure for the specific slag by calculation results, and further improves the thermal stability of the slag by fine tuning the components of the specific slag, so that the smelting production process is more stable. The evaluation method specifically comprises the following steps:
first, slag taken out from the blast furnace is fedOven drying, removing water, grinding into micropowder, and assaying to determine main chemical components (CaO and SiO) 2 、MgO、Al 2 O 3 Etc.). The actual temperature of the slag in the blast furnace is measured on site by a temperature measuring instrument, and is represented by T, and the unit is: K.
wherein the numerical range of the on-site measured temperature T of the blast furnace slag is 1200-1600 ℃;
the main chemical composition range of the slag is mass percent CaO=25-49%; mass% SiO 2 ＝25～49％；mass％MgO＝4～12％；mass％Al 2 O 3 ＝10～25％。
Secondly, assuming that the melt meets the second law of thermodynamics under the condition of high temperature, it is known that under the condition of constant pressure, the enthalpy change value of the slag in a fixed temperature section is equal to the heat input during the temperature rise of the slag, namely:
ΔQ＝ΔU+PΔV＝ΔH
wherein DeltaQ is the total energy change, J, of slag in the heating process; ΔU is the internal energy change value J of slag; p is air pressure, pa; deltaV is the change value of the slag volume, m 3 The method comprises the steps of carrying out a first treatment on the surface of the Δh is the enthalpy change value of the slag during the temperature rise, J.
Third, the main components (CaO, siO) of the slag 2 、MgO、Al 2 O 3 ) Inputting metallurgical thermodynamic calculation software such as Thermo-calc or FactSage according to the mass (or mass percentage) to obtain the enthalpy value H of the slag at 298K 298 。
Fourth, calculate the heat capacity value C of slag at the actual production temperature T pt Enthalpy value H t The enthalpy change value of slag in the heating process is changed from delta H A The representation is:
ΔH A ＝H t -H 298
fifth, there are systematic errors due to metallurgical thermodynamic software data derived from experimental acquisition fits of different periods, here based on NIST Inorganic Crystal Structure Database (ICSD), website: https:// www.nist.gov/srd/nist-standard-reference-database-3 gives the thermodynamic equation for C using the thermodynamic equation p298 、H 298 、C pt 、H t Calculating again to obtain enthalpy change value delta H B . And averaging the enthalpy change value obtained by the reaction formula calculation with the enthalpy change value obtained by the software calculation to obtain an actual enthalpy change value delta H so as to finish the compensation measure for the system error.
C pCaO ＝1.048-2.046×10 4 T -2 -2.388T -1/2 +1.836×10 6 T -3 (T＝298～2845K)
C pMgO ＝1.516-1.541×10 4 T -2 -7.349T -1/2 +1.45×10 4 T -3 (T＝298～3098K)
Wherein C is pi Is the specific heat capacity of a substance i in the slag, wherein the substance i comprises CaO and SiO 2 、MgO、Al 2 O 3 Any one of them; m is m i Mass of substance i; t is the actual calculated temperature;
further, the second enthalpy change value is calculated as follows:
ΔH B ＝∑m i ΔH i
ΔH i is the enthalpy change value of the substance i in the slag; delta tr H i Is the enthalpy of crystallization transition of substance i in the slag; delta l s H i Is the solid-liquid transition enthalpy of the substance i; t (T) tr Is the transition temperature; t (T) M Is the melting temperature of slagA degree; t is the actual calculated temperature; ΔH B Is a second enthalpy change value; m is m i Mass of substance i; s is solid phase crystallization; l is liquid phase crystallization.
Sixthly, as known from the second step, ΔH can be used as the heat input of slag during the heating period; in order to simulate the actual production process, adjusting the slag alkalinity to obtain a plurality of groups of slag with different alkalinity, and repeatedly executing the steps to obtain the actual enthalpy change values of the plurality of groups of slag with different alkalinity; the average value of the actual enthalpy change values of a plurality of groups of slag with different alkalinity is taken as the total heat quantity Q and the unit J required by the slag heating stage. The percentage decrease (increase) of Q is performed, such as 95% Q, 90% Q, 85% Q, 80% Q, 75% Q. In metallurgical thermodynamic software, the mass of the slag component is input again, the set temperature range is 1796-2096K, the step length is 0.1, and the corresponding slag temperature can be obtained after the slag component is matched with 95% Q, 90% Q, 85% Q, 80% Q and 75% Q. The numerical relation between the heat fluctuation and the temperature change is obtained, and the change amplitude of the temperature along with the heat fluctuation can be used for representing the thermal stability of the slag, wherein the larger the change amplitude is, the worse the thermal stability is.
Seventh, at a constant total heat input Q, the temperature T of each alkalinity slag i The following corresponding viscosity is calculated, and the following is set:
wherein VCR is the slag viscosity change rate, eta j And j is a positive integer for slag viscosity.
The calculated VCR values are plotted to produce a numerical display of thermal stability. In the image, the greater the absolute value of VCR, the worse the thermal stability of the slag.
And (3) fine-tuning the proportion of main slag components of the blast furnace, repeating the steps, and selecting the slag component with the best thermal stability as the production and slag distribution optimization direction of the actual slag.
The fine adjustment of the component proportion comprises fine adjustment of components, for example, the components can also be CSMAL-FeO five-membered slag, CSMAL-FeO-TiO 2 Six-membered slag, etc.; binary basicity fine tuning, R limitationRanging from 0.7 to 1.4; the magnesium-aluminum ratio is finely adjusted, and the magnesium-aluminum ratio is limited to be 0.3-1.0.
Examples: blast furnace slag final slag of certain iron works
Firstly, carrying out assay analysis on final slag obtained from a blast furnace in an iron works to determine main chemical components of the slag: mass% cao=42%, mass% SiO 2 ＝35％、mass％MgO＝8％、mass％Al 2 O 3 ＝15％。
The main component of slag (CaO, siO 2 、MgO、Al 2 O 3 ) Inputting the above mass percentages into a reaction balance module of a metallurgical thermodynamic database to obtain the enthalpy value H of the slag at 298K 298 ＝-1438355.2J。
Calculating the enthalpy value H of the slag at the actual production temperature of 1773K by using a reaction balance module in metallurgical thermodynamic software t ＝-1218753.7J,ΔH A ＝219601.5J。
Reusing the relevant thermodynamic reaction to reuse C p298 、H 298 、C pt 、H t Calculating to obtain delta H B = 219573.2J. For DeltaH A And DeltaH B Averaging to obtain Δh= 219587.35J to complete the compensation measure for the systematic error. The slag basicity is adjusted to obtain a plurality of Δh, and an average value of the plurality of Δh is taken as a final Δh (omitted here).
Further, from the second law of thermodynamics, Δh can be set to Q, q= 219587.35J as a heat input criterion of slag during the temperature rise. And (3) increasing and decreasing the percentage of Q: -5%Q = -10979.337J, -10% q= -21958.74J, -15% q= -32938.1J, -20% q= -43917.47J, -25% q= -54896.84J. In the reaction balance module of metallurgical thermodynamic software, the slag components are input again, the set temperature range is 1796-2096K, the step length is 0.1, and the slag temperatures of 95% Q, 90% Q, 85% Q, 80% Q and 75% Q, which are 1703.2K, 1691.2K, 1683K, 1676.2K and 1667.4K respectively, can be obtained after the slag components are matched with 95% Q, 90% Q, 85% Q, 80% Q and 75% Q.
Then, the slag composition was finely adjusted so that the binary basicity of the slag was varied in the range of r=0.8 to 1.3, and as shown in fig. 2, the relationship between the basicity and the temperature of the slag was observed after the above Q (i.e., 95% Q, 90% Q, 85% Q, 80% Q, 75% Q) was constantly inputted, to judge the thermal stability of the slag.
As shown in FIG. 3, the temperature T at which each alkalinity slag is at a constant total heat input Q i The corresponding viscosities are calculated, for example: the basicity of the slag ranges from 0.8 to 1.2 as shown in the table below.
| Alkalinity (basicity) | CaO/％ | SiO 2 /％ | MgO/％ | Al 2 O 3 /％ |
| 0.8 | 34.22 | 42.78 | 8 | 15 |
| 0.9 | 36.47 | 40.53 | 8 | 15 |
| 1 | 38.50 | 38.50 | 8 | 15 |
| 1.1 | 40.33 | 36.67 | 8 | 15 |
| 1.2 | 44.18 | 36.82 | 8 | 11 |
Thus, the calculation of VCR is given by way of example in the following equation: five groups of slag, 0.8-1.2, then the slag Viscosity Change Rate (VCR) is = (viscosity of 0.9-viscosity of 0.8)/viscosity of 0.8, then a plurality of VCR data are plotted as shown in fig. 3.
Wherein VCR is the slag viscosity change rate, eta j And j is a positive integer and represents the slag group number.
It should be noted that, in this document, 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. Without further limitation, an element defined by the phrase "comprising one … …" does not exclude the presence of other like elements in a process, method, article, or apparatus that comprises the element.
The foregoing embodiment numbers of the present invention are merely for the purpose of description, and do not represent the advantages or disadvantages of the embodiments.
The embodiments of the present invention have been described above with reference to the accompanying drawings, but the present invention is not limited to the above-described embodiments, which are merely illustrative and not restrictive, and many forms may be made by those having ordinary skill in the art without departing from the spirit of the present invention and the scope of the claims, which are to be protected by the present invention.
Claims (8)
1. A method for evaluating the thermal stability of blast furnace slag, comprising the steps of:
s1: obtaining the quality and production temperature of each component in the slag;
s2: calculating a first enthalpy change value of the slag heating stage based on thermodynamic software;
calculating a second enthalpy change value of the slag heating stage based on the thermodynamic reaction formula;
s3: taking the average value of the first enthalpy change value and the second enthalpy change value as an actual enthalpy change value;
s4: regulating the alkalinity of slag to obtain a plurality of groups of slag with different alkalinity, and repeatedly executing the steps S1-S3 to obtain the actual enthalpy change values of the plurality of groups of slag with different alkalinity;
s5: based on the second law of thermodynamics, taking the average value of the actual enthalpy change values of a plurality of groups of slag with different alkalinity as the total heat required by the slag heating stage;
s6: inputting total heat into the slag, and calculating the change rate of the slag viscosity after the total heat is input along with the change of the slag alkalinity;
wherein, the larger the absolute value of the viscosity change rate of the slag is, the worse the thermal stability of the slag is;
the first enthalpy change value is calculated as follows:
the mass of each component in the slag is input into thermodynamic calculation software, and the enthalpy value H of the slag at 298K temperature is calculated respectively 298 And the enthalpy value H of the slag at the production temperature T t The first enthalpy change value delta H A ＝H t -H 298 ；
The second enthalpy change value is calculated in the following way:
and inquiring an inorganic crystal structure database according to the quality and the production temperature of each component in the slag to obtain the specific heat capacity of the slag, and calculating a second enthalpy change value by using the specific heat capacity of the slag.
2. The method for evaluating the heat stability of blast furnace slag according to claim 1, wherein the viscosity change rate is calculated as follows:
wherein VCR is the slag viscosity change rate, eta j And j is a positive integer for slag viscosity.
3. The method for evaluating the heat stability of blast furnace slag according to claim 1, wherein the production temperature is in the range of 1200-1600 ℃.
4. The method for evaluating the heat stability of blast furnace slag according to claim 1, wherein the specific heat capacity of the slag is calculated as follows:
C pCaO ＝1.048-2.046×10 4 T -2 -2.388T -1/2 +1.836×10 6 T -3 ,T＝298～2845K；
C pMgO ＝1.516-1.541×10 4 T -2 -7.349T -1/2 +1.45×10 3 T -1 ，T＝298～3098K；
wherein C is pi Is the specific heat capacity of a substance i in the slag, wherein the substance i comprises CaO and SiO 2 、MgO、Al 2 O 3 Any one of them; t is the actual calculated temperature.
5. The method for evaluating the heat stability of blast furnace slag according to claim 1, wherein the second enthalpy change value is calculated as follows:
ΔH B ＝Σm i ΔH i
ΔH i is the enthalpy change value of the substance i in the slag; delta tr H i Is the enthalpy of crystallization transition of substance i in the slag; delta l s H i Is the solid-liquid transition enthalpy of the substance i; t (T) tr Is the transition temperature; t (T) M Is the slag melting temperature; t is the actual calculated temperature; ΔH B Is a second enthalpy change value; m is m i Mass of substance i; s is solid phase crystallization; l is liquid phase crystallization.
6. The method for evaluating the thermal stability of blast furnace slag according to claim 1, further comprising linearly inputting the total heat to the slag, and calculating a rate of change of the slag temperature during the total heat input, wherein the greater the absolute value of the rate of change of the slag temperature, the worse the thermal stability of the slag.
7. A blast furnace slag optimization method, characterized in that the method comprises:
the method for evaluating the heat stability according to any one of claims 1 to 6, wherein the slag component having the smallest absolute value of the change rate of the viscosity of the slag is selected as the optimum slag.
8. The blast furnace slag optimization process of claim 7, wherein the slag component trimming comprises one or more of component trimming, alkalinity trimming and magnesium to aluminum ratio trimming;
wherein the fine-tuning of the components comprises adjusting the components of the slag;
the fine adjustment range of the alkalinity fine adjustment is 0.7-1.4;
the fine tuning range of the magnesium-aluminum ratio fine tuning is 0.3-1.0.
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