RU2371417C2 - Ceramic mixture - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention relates to compositions of ceramic mixtures for making wall structures, mainly brick, and can be used in the industry of construction materials. The ceramic mixture for making bricks contains acidic loam, expanded-clay, residue from filters for removing iron from fresh water, containing the following in wt %: Fe(OH)₃ - 44 to 50 in terms of Fe₂O₃, organic impurities (plant residue) - 10, mineral component: CaCO₃, MgCO₃, CaSO₄ - the rest, in the following ratio of components in wt %: loam - 60 to 85; expanded-clay - 15 to 40; residue from filters for removing iron from fresh water, over 100% - 0.05 to 1.3. The said ratio of components of the ceramic mixture provides for obtaining Al₂O₃ content from 13.4 to 14.5 wt % and Fe₂O₃ - 6.8 to 7.6 in calcinated substance.

EFFECT: increased strength-to-weight ratio and prevention of overall contraction.

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Description

The invention relates to compositions of ceramic materials for the production of bricks (stones) and can be used in the manufacture of building materials and products.

The known composition of the ceramic mass for the production of bricks (stones), including facial, by mixing loam with another type of clay raw material, which, in accordance with the requirements of OST 21-78-88, is unconventional in an individual form for brick, but quite acceptable raw material in as a corrective additive that increases the strength and other properties of wall ceramics given in (see RF Patent No. 2270178, IPC С04В 33/00, published February 20, 2006, Bull. No. 5).

The preparation of the ceramic mass consists in dosing and mixing loam with clay clay substandard for ceramic bricks, for example, pyritized raw materials with preliminary heat treatment to completely burn out organic impurities, as well as transfer pyrite to iron oxide (Fe ₂ O ₃ ), followed by mixing with finely divided additives, performing the role of otoshchiteli, smoothly.

Known ceramic mass has the following advantages:

1. Utilized raw materials for wall ceramics (stones, bricks);

2. Clay raw materials meet the requirements of OST 21-78-88, and enriched (in comparison with loam) with alumina oxide and iron oxide (smooth), which play a significant role in the formation of the structure of ceramic bricks, which ultimately has a positive effect on increasing its strength frost resistance;

3. An increase in the architectural expressiveness of the brick is achieved;

4. Increases the strength and crack resistance of raw brick during drying.

Along with these advantages, there are also disadvantages, specifically:

1. The heat-energy-intensive process of pre-treatment of pyritized clay raw materials and ash TPP;

2. Relatively low compressive strength of 20-27.5 MPa, which does not provide a brick grade higher than Ml25 for facing bricks with high voidness, for example 42%;

3. A relatively low coefficient of structural quality of full-bodied bricks, since pyritized clays contribute to an increase in the average density of bricks, which is 1920 kg / m ³ and higher.

The composition of the ceramic mass known in the article by A.I. Efimov “Application of iron-containing waste in the production of ceramic bricks” is known. M .; VNIIESM, express information, series No. 4, Industry of ceramic wall materials and porous aggregates, issue 3, 1987. (See composition No. 2, page 2, table 1.)

Known composition has the following advantages:

1. Iron-containing sludge and sawdust are utilized;

2. Iron-containing sludge does not require additional grinding;

3. Relatively low brick density.

Along with these advantages, there are also disadvantages, specifically:

1. The insufficiently high strength of the brick, 15-17.5 MPa, which limits the production of face bricks with the brand M125 and above, especially hollow;

2. Low architectural appearance, for example, fading, carbonization spots, which limits the production of facing bricks. Fading is formed due to the content of soluble salts, alkaline and alkaline-earth metals in the iron-containing sludge, and dark spots due to the combustion of sawdust;

3. Low coefficient of structural quality.

The closest composition of the ceramic mass according to the technical solution and qualitative composition is given in the RF Patent No. 2300507 C1, IPC S04V 33/132, publ. 06/10/2007, Bull. No. 16 and including components, with the following ratio:

about.% wt.% - loam 64-66 67-69 - organo-mineral burnable additive (osprey) 6-9 1.6-1.8 - iron-containing waste - fine sediment from cyclones from surface cleaning steel parts and structures shot blasting apparatus 7-13 8.2-12 expanded clay expanded clay 15-20 17,4-23

According to the calculation, the calcined ceramic of the oxides Al ₂ O ₃ 11.65-13.186 wt.% And Fe ₂ O ₃ 8.045-9.11 wt.% Is included in the known composition according to the calculation.

Known composition has the following advantages:

1. Increases the strength of the brick.

2. The architectural look rises.

3. The degree of general shrinkage is reduced due to the small degree of expansion of mixed clay raw materials during the firing process, that is, fire shrinkage is excluded.

Along with these advantages, there are also disadvantages, specifically:

1. Low coefficient of structural quality due to insufficient compressive strength and relatively high average density of solid brick, fired at a maximum temperature of 1000 ° C. The last negative property is promoted by iron-containing waste - precipitate from cyclones from cleaning the surface of steel parts and structures with a shot blasting machine, as well as an insufficient amount of introduced Al ₂ O ₃ oxide (11.65-13.186 wt.%).

2. The process of plastic formation of hole bricks is complicated, due to sticking of osprey cellulose-fiber particles to the press cores, as well as quick wear of the core surface due to friction with very hard steel particles contained in the moldable mass introduced by iron-containing waste.

3. The overall shrinkage is not sufficiently reduced due to the expansion of dry brick during firing, since the introduced iron-containing component (ZhSD) contributes to an increase in the strength of ceramic reinforcement, but has little effect on the degree of expansion.

The objective of the invention is to increase the coefficient of structural quality by eliminating general shrinkage due to expansion during firing within the tolerance of the size of finished products, without reducing the architectural appearance.

To accomplish the task in a ceramic mass for the production of bricks, including acidic loam, expanded clay clay, finely dispersed iron and organomineral wastes, precipitate from filters from deferrization of fresh water containing, wt.%: Fe (finely dispersed) is used as finely dispersed iron and organomineral wastes. OH) ₃ - 44-50 in terms of

Fe ₂ O ₃ , organic impurities (plant residues) - 10, mineral component: CaCO ₃ , MgCO ₃ , CaSO ₄ - the rest, and dosing of all components is carried out on the basis of obtaining in this mixture the content of Al ₂ O ₃ within 13.4- 14.4 wt.% And Fe ₂ O ₃ - 6.8-7.6 wt.% For the calcined substance, and the filter cake from the deferrization of fresh water is introduced in excess of 100% clay mixture based on the calcined substance of the missing amount of Fe2O ₃ in the specified the limit, in the following ratio of components, wt.%:

loam - 60-82;

expanded clay expanded clay - 18-40;

sediment from deferrization filters

fresh water, in excess of 100% - 0.1-1.2.

Characterization of the components adopted in the experiments on the implementation of the composition

1. Loam. In the experiments, five average loam samples were taken from various deposits in the regions of the central region of Russia: the Tula region (from two deposits), the Oryol, Kaluga and Smolensk regions. All loams meet the requirements of GOST 9169-75 in terms of their technological parameters. They are fusible and acidic loamy raw materials having a compressive strength of 11.9-17 MPa at a temperature of 950 ° C. All loams are non-sintering and moderately soft fusible raw materials. The content of sulfur, sulfate impurities meet the requirements of OST 21-78-88. In terms of strength, the crock belongs to low-strength types of clay raw materials. Table 1 shows the chemical composition of the loam, adopted in experimental experiments implementing the proposed method.

Table 1 The chemical composition of loams taken in experiments No. p / p Deposit of acidic loam and related area The content of oxides, wt.% R _cr at t _max = 950 ° C SiO ₂ Al ₂ O ₃ TiO ₂ Fe ₂ O ₃ CaO + MgO K ₂ O + Na ₂ O SO ₃ p.p.p. one Novomoskovsk (Tula region) 72.28 11.64 0.2 4.0 4.39 3.28 traces 4.21 17 2 Osinogorsk (Tula region) 73.36 11.79 0.2 4.39 2,4 3.14 traces 4.82 12.8 3 Safonovskoe (Smolensk region) 75,2 11.55 - 3.9 3.2 3.4 traces 2.75 14.2 four Zdorovetskoe (Oryol region) 75.56 9.6 0.9 3,54 3.95 - traces 4.82 11.9 5 Vorotynskoe I (Kaluga Region) 73.02 11.9 7.09 4.39 2.86 2.59 traces 4.22 13.65

From table 1 it is seen that for the experiments accepted loams containing, wt.%:

SiO ₂ between 72.28-75.56 Al ₂ O ₃ between 9.6-11.9 Fe ₂ O ₃ within the range of 3.54-4.39 CaO + MgO in the range of 2.86-4.39 K ₂ O + Na ₂ O within 2.59-3.28 pp in the range of 2.75-4.82

and with a compressive strength calcined at a temperature of 950 ° C 11.9-17 MPa.

2. Iron-containing waste (ZhSOD) - this is the sediment from the deferrization filters of fresh underground water. Color is light yellow. The particle size is 0-0.315 mm. Dry bulk density ρ = 550 kg / m ³ . Chemical composition, wt.%: Fe (OH) ₃ - 44-50 in terms of Fe ₂ O ₃ , organic impurities 10 - plant residues, the rest is the mineral component: CaCO ₃ , MgCO ₃ , CaSO ₄ .

3. Expanded clay expanded clay.

3.1. Expanded clay of the Bernikovsky deposit of the Tula region (KG-1). This is a highly dispersed clay. Clay is medium plastic, the number of plasticity is 17.8-25.7.

The chemical composition of clay: contains, wt.%: SiO ₂ 40.9-62.28, Fe ₂ O ₃ 10.18-25.7; Al ₂ O ₃ 12.9-24.53; CaO 0.88-4.0; MgO 0.36-3.35; TiO ₂ 0.62-1.02; p.p.p. 1.31 - 11.97.

In terms of refractoriness, clay refers to fusible t _fire. less than 1350 ° C. The expansion coefficient varies from 2.5 to 5.0. The temperature of the start of expansion is 950-1000 ° C. Water absorption from 3% to 7%. The compressive strength is 36–40 MPa.

In the experiment adopted expanded clay clay, containing, wt.%: SiO ₂ 51.59;

Al ₂ O ₃ 18.72; TiO ₂ 0.82; Fe ₂ O ₃ 17.94; CaO + MgO 4.3; pp 6.63.

3.2. Expanded clay of the Porechensky deposit of the Tula region (KG-2) is a semi-acidic and fusible raw material with a swelling start temperature of 950-1000 ° С. In terms of plasticity, clay refers to both medium and highly plastic raw materials with a plasticity number of 19-36. The experiment adopted medium plastic claydite clay with a plasticity number of 22.

The chemical composition of clay: contains, wt.%: SiO ₂ 52.7%, Fe ₂ O ₃ 10.4%; Al ₂ O ₃ 18.4; CaO + MgO 4.5; TiO ₂ 0.75; K ₂ O + Na ₂ O 2,4; SiO ₃ - traces, pp 10.85.

KG-3 - expanded clay mixed from with 50% KG-1 and 50% KG-2. Chemical composition wt.%: SiO ₂ 52.15%; Al ₂ O ₃ 18.56; TiO ₂ 0.785; Fe ₂ O ₃ 14.17%; CaO + MgO 4.4; K ₂ O + Na ₂ O 1,2; pp 8.745.

The implementation of the method of preparation of ceramic mass.

Experience No. 1. Initially, a mixture was prepared from dry powders of acidic loam of the Novomoskovsk deposit (HC), expanded clay clay of the Bernikovsky deposit (KG-1) containing an increased amount of Fe ₂ O _{3 of} 17.94 wt.%. Dosed components were introduced into the dry mixture, respectively, loam 85 wt.% (1360 g) and 15 wt.% (240 g) expanded clay (KG-1). The result was 1600 g.

In this composition of dry alumina, the Al ₂ O ₃ content for the calcined substance was determined by calculation, which amounted to 13.08 wt.%, And the amount of Fe ₂ O _{3 was} 6.22 wt.% (See table 2, mixture No. 1). An iron-containing precipitate from the filters from water deferrization of 0.05% per calcined substance, that is, Fe ₂ O ₃ , in addition to 100% of the specified alumina mixture, was introduced into the mixture. Moreover, in the total mixture, the Al ₂ O ₃ content slightly decreased to 13.01 wt.%, And the Fe ₂ O ₃ content increased by 0.05 wt.% And amounted to 6.27 wt.% (See table 2, the mixture No. 1).

A mixture of dry powders in an amount of 1601.2 g (taking into account the additive) was moistened to molding moisture, manually molded samples 50 × 50 × 50 mm in size, followed by natural drying at room temperature and fired in a muffle furnace at a maximum temperature of 950 ° C and holding 1 hour.

After firing, the samples were tested for indications of general shrinkage, average density and strength. Since ceramic samples of experiment No. 1 had a total shrinkage of 5.1%, which does not correspond to the task, and the compressive strength is less than the strength of the prototype (30.5 MPa), this experiment No. 1 is assigned to the beyond.

Experiments No. 2, 3, 4 were carried out similarly to experiment No. 1, with the only difference being that in each subsequent experiment, the additive was increased — the filter cake from the deferrization of fresh water and the amount of clay clay KG-1 containing 17.94 Fe ₂ O ₃ wt .%.

Experiment No. 5 was carried out similarly to experiment No. 1, but with a large amount of additive - filter cake from deferrization of fresh water, and also mixed claydite clay was used from 50% KG-1 and 50% KG-2 containing 14.17 Fe ₂ O ₃ wt.%.

Experiments No. 6, 7, 8, 9 were carried out similarly to the previous ones, but with expanded clay clay KG-2 containing 10.4 Fe ₂ O ₃ wt.% And with a large amount of additives - filter cake from the de-ironing of fresh water. Experience No. 9 is transcendent, since the strength is practically not higher than in the prototype method.

Experience No. 10, 11. The preparation of the ceramic mass by the prototype method was carried out in the traditional way, that is, all components of the mixture are dosed and mixed in a certain ratio (see table 2, mixture No. 10, 11). In the prototype method, there are fundamental differences from the proposed, specifically:

1. There is no stage of theoretical calculation to determine the amount of alumina and Fe ₂ O ₃ oxides without and with an additive (ZhSD), which have a very strong influence (especially Fe ₂ O ₃ ) on the expansion of expanded clay during firing and general shrinkage (see Rogova M.I. . Technology of artificial aggregates and ceramics: Textbook for high schools. - M .: Stroyizdat, 1974, p. 82-84);

2. In the prototype method, the composition corresponding to the maximum strength with a slightly reduced overall shrinkage is adopted for the optimal mass composition. In the proposed method, the composition with zero general shrinkage and with the provision of achieving higher strength compared to the prototype method with a simultaneous decrease and average density is adopted for the optimal composition of the mass being prepared, which contributes to an increase in the coefficient of structural quality (c.c.) .

table 2 The test results of the optimal composition of the masses prepared by known and proposed methods No. p / p The optimal composition of the masses prepared by the proposed method, wt.% The number of introduced oxides, wt.% Properties of ceramics from optimal masses Compressive strength R _SJ, MPa The average density ρ, kg / m ³ c.k.k. K = R _cr / ρ General shrinkage,% The presence of salting Al ₂ O ₃ Fe ₂ O ₃ one NS-85

30.5 1840 0.0166 5.1 no (KG-1) -15 ZhSOD-0,05> 100% 2 OGS-82

38.5 1845 0.02 0 no (KG-1) -18 ZhSOD-0,1 3 NS-80

41.41 1855 0,022 0 (+1.2) no (KG-1) -20 ZhSOD-0.3 four SAS-75.3

39.1 1860 0,021 0 (+2.5) no (KG-1) -24.7 ZhSOD-0.5 5 OGS-79.1

40,2 1850 0,022 0 (+1.8) no (KG-3) -20.9 ZhSOD-0.57 6 OGS-66

43 1900 0,023 0 (+1.8) No (KG-2) -34 ZhSOD-1 7 VRS-70

42.8 1895 0.0225 0 (+1.2) No (KG-2) -30 ZhSOD-1,1 8 ZDS-60

32,5 1890 0.0172 0 (+2.0) no (KG-2) -40 ZhSOD-1,2 9 ZDS-67

31.8 1885 0.0168 0 (+6) no (KG-2) -33 ZhSOD-1,3 10 Prototype 11.65 8,045 20.7 1920 0.011 8.0 no OGS-67 Skop-1.8 JSD-8.2 (KG-1) -23.0 eleven Prototype 13,186 9.11 31.5 1921 0.016 8.5 no OGS-69 Scop 1.6 JSD-12.4 (KG-1) -17.0

Note: 1. ZhSOD enter in excess of 100% alumina; in parentheses indicate the amount of Fe ₂ O ₃ wt.%, that is, Fe (OH ₃ ) per calcined substance.

2. Indices: NS - Novomoskovsky, OGS - Osinogorsk, САС - Safonovsky, VRS - Vorotynsky loam, (KG-1) - expanded clay clay containing Fe ₂ O ₃ 17.94 wt.%, (KG-2) - expanded clay containing Fe ₂ O ₃ 10.4 wt.%, (KG-3) - mixed expanded clay clay (KG-1) 50% :( KG-2) 50%; ZhSOD - iron-containing waste-sediment from filters from deferrization of fresh water in terms of

Fe ₂ O ₃ ;

ZhSD - iron-containing dust from cyclones from cleaning the surface of steel parts and structures with a shot blasting apparatus.

3. The numerator indicates the content of Fe ₂ O ₃ in the mixture of loam with expanded clay. The denominator contains the content of Fe ₂ O ₃ in the mixture of all components and with the addition of ZhSD.

4. In parentheses, an increase in the size of the samples relative to the dimensions of the raw sample (mm).

Analysis of the results obtained by implementing the method of preparation of ceramic mass:

The proposed method, in comparison with the known method (prototype), has the following advantages:

- the coefficient of structural quality is increased by 1.4-1.5 times due to an increase in strength by 26.7-57% and a decrease in average density by 1.5-4%;

- total shrinkage is completely eliminated due to the correct ratio of% Al ₂ O ₃ and% Fe ₂ O ₃ in the mixture. The latter contributes to a large degree of expanded clay clay, and at a lower temperature of 950 ° C;

- expanded the scope of natural expanded clay clays having a lower content of Fe ₂ O ₃ 10.4 wt.%, and in the composition of the prototype 17.94 wt.%. This is also facilitated by the addition of ZhSOD - an iron-containing waste from deferrization of fresh water (mainly Fe (OH) ₃ );

- it utilizes a less-used, but more common waste - filter cake from fresh water purification, which is environmentally friendly, acting as a pigment, as it imparts a brighter red color to the brick;

Physico-chemical essence of the achievement of the task

1. The following factors contribute to an increase in the degree of expansion of dry mass during firing up to the exclusion of general shrinkage:

a) an increase in the amount of reactive Fe ₂ O ₃ (melt) by a corresponding increase in the amount of expanded clay clay 18-49% (in the prototype 17-23 wt.%) and additionally introduced organo-iron additives, that is, Fe (OH) ₃ + organic, which is and an additional blowing agent that increases the expansion of expanded clay and the porosity of the mass in accordance with chemical reactions that occur during firing:

2Fe (OH) 3 → Fe ₂ O ₃ + 3H ₂ O pairs ↑

b) as a result of the reduction of Fe ₂ O ₃ in FeO, gases are released:

6Fe ₂ O ₃ → 4Fe ₃ O ₄ + O ₂ ↑ gas;

2Fe ₃ O ₄ → 6FeO + O ₂ ↑ gas;

Pe2O ₃ + 02РеО + СО ↑ gas;

Fe ₂ O ₃ + CO = 2FeO + CO ₂ ↑ gas.

The presence of organic impurities in the sediment from filtration helps to ensure a reducing medium inside the ceramic mass (during firing) during the transition Fe ₂ O ₃ → FeO (see Rogovoy M.I. Technology of artificial aggregates and ceramics: Textbook for high schools, Moscow: Stroyizdat, 1974 , p. 82-84), as well as a decrease in average density. Based on paragraphs “a, b”, the amount of the additive is regulated (in terms of Fe ₂ O ₃ ) over 100% of the alumina mixture, since the excess of the additive not only helps to eliminate general shrinkage, but also increases the size of the products above (± 5; ± 4; ± 3 mm). The method provides no more than 3 mm. The last consideration is limited and the content of Fe ₂ O ₃ (within certain limits).

2. The increase in strength at a temperature of 950 ° C is facilitated by an increase in the composition of the mass in comparison with acidic loam, the amount of alumina Al ₂ O ₃ , but up to a certain amount in the range of 13.4 to 14.5 wt.%, Since with a lower content of Al ₂ O ₃ , an increase in strength is not achieved, and at more than 14.5 wt.%, The mass becomes more refractory and at a firing temperature of 950 ° C, brick underburning and, accordingly, a decrease in strength are observed. With an increase in Fe ₂ O ₃ oxides above 7.6 wt.%, An excessive mass expansion is observed during firing, that is, the size of ceramic products is beyond the tolerances for finished bricks.

In the composition of the prototype, the content of iron-containing microparticles exceeds 7.6% (8.045-9.11), since this composition also contains oxidized microparticles of steel, which have refractoriness and do not affect the amount of expanded clay clay and the whole mixture. Therefore, general shrinkage is not completely excluded and amounts to 8.5%.

4. An integrated approach to increasing the volume of finished products by expanding the mass during firing, with the exception of general shrinkage while increasing strength, increases the coefficient of structural quality. The last factor contributes to the addition of ZhSD.

The technical and economic feasibility of the method of preparation of ceramic mass is as follows:

1. Disposed of poorly used finely dispersed, and environmentally friendly waste - sediment from filters from deferrization of fresh water (mainly Fe (OH) ₃ ) that do not require pre-treatment (drying, grinding);

2. Clay raw materials are saved by the total shrinkage of 8-10% due to the corresponding exclusion of an increase in the cross section of the mouthpiece;

3. Heat and energy costs are saved, since the firing temperature is reduced by 50 ° C;

4. The main economic feasibility of the proposed method for the preparation of ceramic masses based on acidic low-strength loam with the addition (adjustment) to them of stronger semi-acidic clays that can swell during firing, while increasing strength, due to the enrichment of acidic loams Al ₂ O ₃ and more reactive fluff Fe ₂ O ₃ within certain limits, is to reduce the time to develop the optimal composition of the mass and introduce it into production practice. Correspondingly, labor and energy costs are reduced in case the plant transfers to a new deposit of loam and expanded clay. So, for example, to develop the composition of the mass of the prototype required more than 50 experiments in the laboratory for 1.2 years. To develop the optimal mass composition by the proposed method, for example, when switching to a new deposit of acidic loam or expanded clay clay and with a known chemical composition of the accepted raw materials, it will take 1-2 hours to work with a computer, with subsequent verification of the designed optimal mass composition by experience;

5. The specified economic feasibility allows to reduce the cost of the method by 20-25%.

Claims (1)

Ceramic mass for the production of bricks, including acidic loam, expanded clay clay, finely dispersed iron and organomineral waste, characterized in that as a finely dispersed iron and organomineral waste, a filter cake from the deferrization of fresh water containing, wt.%: Fe ( OH) ₃ - 44-50 in terms of Fe ₂ O ₃ organic impurities (plant residues) - 10, mineral component: CaCO ₃ , MgCO ₃ , CaSO ₄ - the rest, in the following ratio, wt.%:
Loam 60-85 Expanded clay expanded clay 15-40 Sludge from de-ironing filters fresh water, in excess of 100% 0.05-1.3
moreover, the specified ratio of the components of the ceramic mass provides obtaining in it the content of Al ₂ O ₃ in the range of 13.4-14.5 wt.%, and Fe ₂ O ₃ - 6.8-7.6 wt.% per calcined substance.