RU2527393C2 - Method of selecting composition of heat-resistant stone casting - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention relates to selection of mineralogical composition of heat-resistant stone casting for operation under conditions of higher temperatures 250-900°C, which can be used at enterprises of metallurgical, chemical, ore mining and processing, power and other fields of industry. On diagram "albite-anortite-diopside" (Al-An-Di) in the field 1300-Di-1300°C figurative point of composition of heat-resistant stone casting is selected, quantitative content of components SiO₂, Al₂O₃, CaO, MgO, Na₂O is selected on the diagram in said point and selection of appropriate industrial mineralogical composition is performed. After that, recalculation is carried out with quantitative combination of free Fe₂O₃ with Al₂O₃, and TiO₂, MnO, FeO with MgO, and after that, with application of specified quantitative content of SiO₂, Al₂O₃, CaO, MgO, Na₂O determined are: figurative point on the diagram, quantitative content of SiO₂, Al₂O₃, CaO, MgO, Na₂O in said point, with further estimation of corresponding it physical-mechanical parameters: for points, located in the field of diagram Al-An-Di above the liquidus line 1300-1300°C, composition can be used in production, for points below liquidus line 1300-1300°C it is necessary to select new industrial composition.

EFFECT: more accurate selection of stone casting compositions with preliminarily specified characteristics and account of admixtures, present in raw materials.

3 tbl, 9 dwg

Description

The invention relates to the selection of the mineralogical composition of heat-resistant stone casting, operating at elevated temperatures of 250-900 ° C, which can be used in enterprises of metallurgical, chemical, mining, energy and other industries.

When choosing the compositions of heat-resistant stone casting, as a rule, they take the compositions of well-known stone foundries and increase the strength properties and, accordingly, the operating temperatures of operation due to the introduction of mineralizers — Cr ₂ O ₃ , TiO ₂ , ZrO ₂ , Ba ₂ O ₃ , Fe ₃ C and others. This method of selecting the composition of stone casting is long in time and requires a large number of physicochemical studies (List of products. Catalog. Pervouralsky plant of mining equipment, 2002).

The closest is the method of choosing the composition of stone casting (Art. N. N. Ormont “On the use of an asymmetric state diagram for characterizing the physicochemical properties of basalts and diabases.” Moscow University Bulletin, No. 5, 1950, prototype) using the diagram “ albite-anorthite-diopside ”(Al-An-Di, where: Al - Na ₂ O _3, Al ₂ O ₆ , 6SiO ₂ ; An - CaO, Al ₂ O ₃ , 2SiO ₂ ; Di - CaO, MgO, 2SiO ₂ ), comprising selecting the figurative point in the chart, determining the quantitative content at this point five components SiO _2, Al ₂ O _3, CaO, MgO, Na ₂ O and selection of appropriate industrial th composition of the raw materials.

The method of choosing the composition of stone casting, proposed N.N. Ormont, allows you to determine the chemical composition of the melt at any point in the diagram, pre-analyze the processes of mineral formation, the sequence of separation of minerals and the effect of individual oxides on the technological and strength properties of castings.

As a rule, charge materials, in addition to the basic oxides SiO ₂ , Al ₂ O ₃ , CaO, MgO, Na ₂ O, contain in small quantities, up to 6%, their accompanying impurities TiO ₂ , MnO, FeO, Fe ₂ O ₃ or specially introduced Cr ₂ O ₃ and others. Due to the presence of these impurities in the chemical composition of stone casting, the corresponding figurative point shifts in the field of the Al-An-Di diagram and the physicochemical properties of stone casting change accordingly.

The basis of the invention is the task to improve the method of selecting the composition of heat-resistant stone casting using the Al-An-Di diagram by taking into account impurities in industrial compositions and recalculating the composition of the main elements, which will speed up the choice of the composition of stone casting with predetermined characteristics.

In order to take them into account when calculating the composition of the figurative points in the Al-An-Di diagram, the authors propose to include impurities in the main composition of the diopside-pyroxene phase:

1. Iron oxides Fe ₂ O ₃ and FeO in the form of magnetite Fe ₃ O _4, consisting of one weight part of FeO and 2.22% Fe ₂ O ₃ , having a melting point of more than 1800 ° C, is the first to precipitate and acts as crystallization centers for subsequent formed phases.

2. It is known that trivalent Fe3 ⁺ and Al ³⁺ isomorphically replace and complement each other, are part of pyroxenes. Therefore, unused Fe ₂ O ₃ combined with Al ₂ O ₃ .

3. TiO ₂ , MnO, and FeO remaining unused have MgO with close ion radius sizes of 0.75-0.82.10 ^-8 , identical coordination numbers of 6, and close electronegativity of 170-220 kcal / g atom, which allows them to According to the authors, together with MgO it is isomorphic to replace each other in the formula of diopside Ca (Mg, Fe, Ti, Mn) Si ₂ O ₆ , participating in the formation of mineralogical phases based on diopside and pyroxenes.

The problem is solved in that in the method for selecting the composition of heat-resistant stone casting, including the selection of a figurative point in the field 1300-Di-1300 of the diagram “albite-anorthite-diopside” (Al-An-Di), determination of the quantitative content of components at this point in the diagram SiO ₂ , Al ₂ O ₃ , CaO, MgO, Na ₂ O and the selection of the appropriate industrial mineralogical composition, according to the invention, are then recalculated - quantitatively combine free Fe ₂ O ₃ with Al ₂ O ₃ , a TiO ₂ , MnO, FeO with MgO , and the specified quantitative content of the components SiO ₂ , Al ₂ O ₃ , CaO, MgO, Na ₂ O additionally determines on the diagram a figurative point and the quantitative content of SiO ₂ , Al ₂ O ₃ , CaO, MgO, Na ₂ O components at this point, and the physicochemical parameters corresponding to it are estimated using the albite-anorthite-diopside diagram - for points that are located in the chart field above the liquidus line 1300-1300 ° C, the industrial composition can be used in production, and for points located below the liquidus line 1300-1300 ° C it is necessary to select a new industrial composition.

When choosing the chemical composition of heat-resistant stone casting, the authors relied on the recommendations accumulated during its production and operation:

1. The higher the temperature of the liquidus of the melt above the temperature at which products made of heat-resistant castings are operated, the longer their service life.

2. The number of mineralogical phases should be minimized, which reduces the amount of residual stresses in the castings.

3. The more uniform the structure over the thickness of the casting, the lower the level of shrinkage and residual stresses.

4. The difference between the temperature of the product in use and the liquidus temperature must be at least 400 ° C.

To solve these problems when developing compositions of heat-resistant stone casting, the authors propose to use a triple diagram of “albite-anorthite-diopside” (Al-An-Di) (Figs. 1 and 2), namely, the section located in the diagram field above the liquidus line 1300- 1300 ° C.

Table 1 shows the chemical compositions of the selected figurative points 1, 2, 3, 4 and 5.

Table 1 The chemical composition of the figurative points in the field of the Al-An-Di diagram The name of the charge (industrial composition) Content-
% SiO ₂ Al ₂ O ₃ CaO MgO Na ₂ O Fe ₂ O ₃ FeO TiO ₂ MnO Cr ₂ O ₃ Figurative point 1 one hundred 55.5 - 25.9 18.6 - Figurative point 2 one hundred 60.9 8.4 14.8 10.8 5.1 Figurative point 3 one hundred 51,4 12,4 23.6 12.6 - Figurative point 4 one hundred 54.3 9.0 21.8 13.8 1,1 Figurative point 5 one hundred 53.0 10.6 22.58 13,2 0.7

The presence on the diagram "albite-anorthite-diopside" of the temperatures of the liquidus lines and the viscosity data of reference points within 1300-Di-1300 (Fig. 1 and Fig. 2) allows us to analyze the processes of mineral formation, the sequence of allocation of minerals and the effect of individual oxides on technological and strength properties of castings.

The viscosity characteristics of the melts within the field 1300-Di-1300 are 60-170 poise. Such melts are suitable for casting products of any complexity.

To determine the figurative points within the field at any point of the triangle 1300-Di-1300, the authors used the method proposed by N.N. Ormont, with the introduction of improvements developed and confirmed by the authors in the process of numerous laboratory and industrial experiments.

The proposed method is illustrated in the figures:

Figure 1 - presents a diagram of "albite-anorthite-diopside" indicating the percentage of basic oxides on the sides of the triangle;

Figure 2 is a diagram of Al-An-Di indicating the temperature and viscosity characteristics in the field of the diagram, including in the field 1300-Di-1300.

Figure 3 is a template for determining the content of Na ₂ O in a diagram;

Figure 4 is a template for determining the MgO content in a diagram;

Figure 5 is a template for determining the CaO content in a diagram;

6 is a template for determining the content of Al ₂ O ₃ in a diagram;

7 is a template for determining on the diagram the content of SiO ₂ ;

On Fig - diagram of Al-An-Di in the XY coordinate system to determine the position of the figurative point 4-1 with the calculated content of components SiO ₂ , Al ₂ O ₃ , CaO, MgO, Na ₂ O (table 1, 2).

Figure 9 is a diagram of Al-An-Di in the XY coordinate system for determining the position of the figurative point 5-1 with the calculated content of components SiO ₂ , Al ₂ O ₃ , CaO, MgO, Na ₂ O (table 1, 2). An example of the method.

For example, we select on the diagram "albite-anorthite-diopside" two figurative points 4 and 5 (figure 2, table 1).

We make the templates shown in Figs. 3, 4, 5, 6, 7, which are proposed and described in the methods described in the closest analogue (Art. N. N. Ormont “On the use of an asymmetric state diagram for characterizing the physicochemical properties of basalts and diabases ”,“ Bulletin of Moscow University ”, a series of physical, mathematical and natural sciences, issue 3, 1950, No. 5, pp. 117-132).

Templates are made in the form of:

- right triangles for determining the percentage of oxides SiO ₂ , MgO, Na ₂ O;

- triangle with an angle of 48 ° - for CaO;

- a triangle with an angle of 27 ° - for Al ₂ O ₃ .

Using the templates, draw straight lines through the selected figurative points of points 4, 5 on the sides of the triangle of the Al-An-Di diagram (Fig. 1) and determine the percentage of oxides. The total amount of oxides should be 100% (tab. 1). Based on the obtained values of oxides, we select the composition of the industrial charge — compositions 4-1 and 5-1 (Table 2) —and determine the chemical composition of the main oxides and impurities. We determine the amount of magnetite and high-temperature mineralizers that will not participate in subsequent calculations, combine the remaining Fe ₂ O ₃ with Al ₂ O ₃ , a FeO, TiO ₂ , MnO with MgO and recalculate to determine the 100% content of the five basic oxides of SiO ₂ , Al ₂ O ₃ , CaO, MgO, Na ₂ O.

To determine the location of the figurative points on the Al-An-Di diagram using templates 3, 4, 5, 6 and 7, we draw straight lines from the points that determine the percentage obtained when calculating the five basic oxides of industrial compounds 4-1 and 5-1 (figure 1).

The resulting lines of compositions 4-1 and 5-1 are transferred to the X-albit-Y coordinate system (Figs. 8, 9). As can be seen in Fig. 8, straight lines have 10 intersection points with each other. The distance from the intersection point to the coordinate line X and Y in mm is recorded, averaged and transferred to the Al-An-Di diagram to determine the location of the figurative points 4-1 and 5-1 (Figs. 8, 9).

Below is the calculation and location of the figurative point 4-1 in Fig.8.

Albit-Y = 68 + 60 + 60 + 60 + 60 + 60 + 58 + 56 + 53 + 27 = 562: 10 = 56.2

Albit-X = 68 + 60 + 60 + 55 + 55 + 55 + 55 + 54 + 52 + 48 = 562: 10 = 56.2

We draw straight lines at an angle of 90 ° from the X-Y line at a distance of 56.2 and 56.2 mm and at the point of their intersection we determine the location of the figurative point 4-1 on the Al-An-Di diagram.

Using the same scheme, we determine the location of the figurative point 5-1 on the Al-An-Di diagram (Fig. 9).

Albite-Y = 50 + 55 + 55 + 56 + 56 + 57 + 57 + 62 + 62 + 62 = 572: 10 = 57.2

Albit-X = 57 + 60 + 60 + 60 + 62 + 62 + 62 + 67 + 67 + 72 = 629: 10 = 62.9

Then we prepare from the mineral raw materials the composition of the charges, similar in chemical composition to the figurative points 4 and 5 (table 2).

table 2 Examples of calculating the chemical composition of the figurative points 4-1 and 5-1 The name of the charge (industrial composition) Content-
% SiO ₂ Al ₂ O ₃ CaO MgO Na ₂ O Fe ₂ O ₃ FeO TiO ₂ MnO Cr ₂ O ₃ Figurative point 4 one hundred 54.3 9.0 21.8 13.8 1,1 Industrial composition: Blast furnace slag 35.0 Dolomite 7.0 Quartz sand 13.0 Pereklazokhromit 10.0 Granite Screenings 35.0 Carry out a chemical analysis of the industrial charge one hundred 53.08 9.13 20.24 12.0 1.46 1,54 0.4 0.25 0.35 1.55 We recalculate (wt.%): 0.89% Fe ₂ O ₃ + 0.4% FeO = 1.29% magnetite and 1.55% Cr ₂ O _{3 are} not taken into account in further calculations 0.65% Fe ₂ O ₃ + 9.13 Al ₂ O ₃ = 9.78 Al ₂ O ₃ (total) 0.25% TiO ₂ + 0.35% MnO + 12.0% MgO = 12.6% MgO (total) 97.27 53.08 9.78 20.24 12.7 1.46 The resulting composition is recalculated to 100 wt.% Figurative point 4-1 one hundred 54.57 10.06 20.81 13.06 1,50 The name of the charge (industrial composition) Content-
% SiO ₂ Al ₂ O ₃ CaO MgO Na ₂ O Fe ₂ O ₃ FeO TiO ₂ MnO Cr ₂ O ₃ Figurative point 5 one hundred 53.0 10.6 22.5 13,2 0.7 Industrial composition: Dolomite 44.0 Pereklazokhromit 3.0 Fire-clay 7.0 Quartz sand 46.0 Carry out a chemical analysis of the industrial charge one hundred 51.62 10.32 22.11 12.79 0.56 1.45 0.25 0.1 0.1 0.7 We recalculate (wt.%): 0.55% Fe ₂ O ₃ + 0.25% FeO = 0.80% magnetite and 0.7% Cr ₂ O _{3 are} not taken into account in further calculations 0.9% Fe ₂ O ₃ + 10.32.% Al ₂ O ₃ = 11.22.% Al ₂ O ₃ (total) 0.1% TiO ₂ + 12.79% MgO + 0.1% MnO = 12.99% MgO (total) 98.5 51.62 11.22 22.11 12,99 0.56 The resulting composition is recalculated to 100 wt.% Figurative point 5-1 one hundred 52.40 11.39 22.45 13.19 0.57

Table 3 shows the physicomechanical characteristics of stone casting compositions of figurative points 1, 2, 3, 4, 4-1, 5, 5-1.

Table 3 Physico-mechanical characteristics of stone casting compositions Technological parameters Figure Point Number on Al-An-Di Chart one 2 3 four 4-1 5 5-1 Temperature ° C at liquidus 1390 1310 1280 1320 1310 1310 1305 Melt viscosity in poises with liquidus 83 234 158 165 160 146 148 Melt viscosity in poises at + 25 ° C 80 178 138 136 130 138 140 Melt viscosity in poises at + 50 ° C 78 148 120 120 118 128 126 Liquid flow, mm (when filling channels каналов8 mm) 45 twenty 40 35 35 35 34 Heat resistance, heat exchange, 900-20 ° C on plates 200 × 200 × 25 28 16 26 28 26 24 23 Compressive strength, MPa (on samples 20 × 20 × 20 mm) 200 180 300 280 300 180 220

The compositions of the figurative points 1, 2, and 3 located at the extreme points of the field of the triangle 1300-Di-1300 of the Al-An-Di diagram are usually not used, because do not contain the optimal composition of oxides, providing sufficient heat resistance and strength of stone casting.

The viscosity characteristics and fluidity of the melts located in the Al-An-Di diagram field above the eutectic line 1300-1300 ° C make it possible to produce stone products of any complexity (Table 3).

Heat resistance of plates 200 × 250 × 25 mm above 20 heat exchangers at 900-20 ° C is recommended for operation in any industrial conditions.

Samples of castings of compositions of figurative points located in the upper part of the field of the Al-An Di diagram contain up to 80% of diopside with a homogeneous structure and grain size of 0.1-0.15 mm. The gaps between the crystals are filled with residual glass (10-15%) and wollastonite formations, i.e. the structure contains only 3 phases - diopside, wollastonite, glass.

Closer to the line 1300-1300 ° C in the field of the structure diagram of the composition of figurative points, which are on the right side of the Al-An-Di diagram, replenished with anorthite components mainly pyroxene composition by increasing the content of Al ₂ O ₃ , which increases the strength properties of castings, but while reducing heat resistance by reducing the content of CaO and MgO.

On the left side of the diagram, the figurative points are enriched with albite components mainly in the form of plagioclase due to an increase in the content of Na ₂ O and a decrease in the amount of MgO. The percentage of glass, which reduces the crystallization ability of the melt, and, accordingly, the heat resistance and strength properties of castings, significantly increases.

The figurative points of the compositions of heat-resistant stone casting located in the field of the diagram on the line 1300-1300 ° C or below it can be used in operating conditions of temperatures lower than 900 ° C.

As practice shows, the interaction of basic oxides in the production of heat-resistant castings is influenced by a large number of factors: the constancy of the chemical composition of the charge used, temperature fluctuations in the furnace during melting and cooling of castings, environmental humidity, etc. Therefore, the most reliable way to assess the suitability of an industrial charge is chemical analysis of the resulting products.

The petrographic analysis of the selected compositions in the field 1300-Di-1300 of the Al-An-Di diagram confirms their high quality (Table 3) and confirms the method proposed by the authors for choosing the composition of heat-resistant stone casting.

As shown by studies of the processes of melting and solidification of stone products (Khan B.Kh., Bykov II and others. “Solidification and crystallization of stone casting", 1969. Collection "Problems of stone casting", 1975), the temperature of casting stone of melts is 20-100 ° C above the melting temperature, the solidification process of the casting is stretched by 100-400 ° C during the cooling process and the choice of pouring temperature 50 ° C above the liquidus line is quite justified.

The composition selected by this method ensures the thermal stability of the plates 200 × 200 × 30 for at least 20 heat exchanges at 900–20 ° C and the melt viscosity at a temperature of 50 ° C above the melting point of at least 120 poises.

The method of choosing the chemical composition of heat-resistant stone products using the advanced Al-An-Di diagram has been tested at stone-making enterprises and can be widely used by specialists in the development of technologies.

Claims (1)

The method of choosing the composition of heat-resistant stone casting by selecting the figurative point on the diagram "albite-anorthite-diopside" (Al-An-Di) in the field 1300-Di-1300 ° C, determining the quantitative content of SiO ₂ , Al ₂ components on this diagram O ₃ , CaO, MgO, Na ₂ O and the selection of the appropriate industrial mineralogical composition, characterized in that then they are recalculated - quantitatively combine free Fe ₂ O ₃ with Al ₂ O ₃ , and TiO ₂ , MnO, FeO with MgO and after that the specified quantitative content of the components SiO ₂ , Al ₂ O ₃ , CaO, MgO, Na ₂ O is again determined on the diag For example, a figurative point, the quantitative content of SiO ₂ , Al ₂ O ₃ , CaO, MgO, Na ₂ O components at this point and the corresponding physical and mechanical indicators are estimated using the diagram “albite-anorthite-diopside” - for points that are located in the chart field above the liquidus line 1300-1300 ° C, the industrial composition can be used in production, and for points below the liquidus line 1300-1300 ° C, it is necessary to select a new industrial composition.

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