RU2414442C1 - Composition for wall ceramic - Google Patents

Abstract

FIELD: chemistry. ^ SUBSTANCE: invention relates to compositions of ceramic mixtures for making wall construction articles, mainly bricks. The composition for wall ceramic contains semi-acidic clay containing over 20 wt % Al2O3, including pyritised, clay which contains sulphate and sulphite impurities (over 2% in terms of the SO3Çè-2 ion), hemihydrate gypsum -CaSO40.5H2O, expanded vermiculite with particle size 0-1.25 mm, liquid silicate glass with density 1.3 g/cm3 and acidic loam, with the following ratio of components, wt %: acidic loam 18-50; said clay 28-42; gypsum hemihydrate 20.5-37; expanded vermiculite 1.5-3, liquid silicate glass over 100% of the dry mixture 0.2-0.5. ^ EFFECT: high average density and strength of articles. ^ 3 tbl

Description

The invention relates to compositions of ceramic masses for the manufacture of wall building products of predominantly effective and conditionally effective bricks and porous-hollow stones, and can be used in the building materials industry.

The known composition of porous ceramics for thermal insulation of walls, mainly thermal units, including wt.%:

expanded vermiculite 40-50; highly plastic clay 50-60.

(see K.E. Goryainov, K.N. Dubenetsky, S.G. Vasilkov and others. Technology of heat-insulating materials and light concrete. - M .: Publishing house of building literature - 1966, p. 212, paragraph "but".).

Advantages of ceramic products made on the basis of known mass composition:

- simple technology for the formation of semi-finished products - casting method with short-term vibration;

- products are used for thermal insulation of the surface of thermal units with temperatures up to 1000 ° C;

- contains only two components.

Along with the advantages of the composition of the ceramic mass, there are also disadvantages:

- low density and strength of the product (average density 300 kg / m ³ , tensile strength in bending of 1.8-2 kgf / cm ² (0.18-0.2 MPa)), which limits the use of products for self-supporting structures of walls of residential and industrial buildings, including for walls of thermal units.

Known and the second composition of the ceramic mass for wall ceramics, is given in the patent of the Russian Federation No. 2270178, IPC ⁷ С04В 33/00, publ. 02/20/2006. Known composition includes, wt.%:

clay fusible raw materials (loam + semi-acid pyritized clay) 83-85; - heat treated: 1) carbon-containing refractory clay 8.5-10; 2) low calcium lignite ash 2.0-5; cullet (ground) 0.9-1.5; finely expanded vermiculite filler fractions 0-1.25 mm 1.5-2; chalk production waste containing hydrated lime 48-49 wt.% 0.1-0.5.

Based on the known composition of the ceramic mass, wall bricks are obtained with increased density (more than 1400 kg / m ³ ) and a sufficiently high strength grade of at least M100.

Along with the advantages of the known composition of the mass, there are the following disadvantages.

1. It is impossible to obtain porous ceramics from a known mass, for example, conditionally effective with an average density of not more than 1400 kg / m ³ , since the spoiling gases are previously removed by heat treatment.

2. Heat and mechanical energy-intensive mass preparation process associated with preliminary heat treatment and subsequent crushing of heat-treated components, as well as the formation of semi-finished products by semi-dry or extrusion molding methods.

3. High average density of full-bodied products (more than 1400 kg / m ³ ).

The closest composition of the ceramic mass for the manufacture of porous ceramics with high thermal insulation properties is given in the book (II Moroz. Technology of building ceramics. - Kiev: - 1980, p. 348). The known composition includes components in the following ratio, wt.%:

perlite expanded sand 45; clay 45; gypsum semi-aquatic 10; air-entraining additive "PO-6" 7 (in excess of 100% dry mix);

Along with great advantages (low average density 200 kg / m ³ - 300 kg / m ³ , respectively low thermal conductivity - 0.06 W / m ° C, simple molding technology (casting into molds), there are the following disadvantages.

1. Low strength of finished products: with a bend of 0.2-0.5 MPa, with a compression of 0.5-1 MPa (see Yu.P. Gorlov. Technology of heat-insulating and acoustic materials and products. - M: Higher school. - 1989, p.195, table.9.2.), Which limits their use as effective, conditionally effective and porous-full-bodied stones with the brand M100, respectively, and for stones no lower than M 35 (GOST 530-2007).

2. The low strength of the semi-finished products (with a compression of 0.1 MPa) formed by pouring into molds, which complicates the process of form stripping and drying, since the drying of semi-finished products is carried out on pallets of products (see the manufacturing method in the prototype).

3. Low architectural appearance - since the color of the crock is red with the presence of efflorescence, due to the large amount of PO-6 added and the lack of semi-aquatic gypsum. The latter, as is known, performs not only the role of a porizer, a stabilizer of a slip, but also a bleach that transforms a red-burning shard into a light-burning one.

The objective of the invention is to increase the average density and strength to the parameters of effective and conditionally effective ceramics (class 1.2; 1.4), as well as architectural expressiveness by obtaining light tones of the shard (light cream, cream) without efflorescence.

To accomplish this, as part of the mass for wall ceramics, including clay, gypsum β-CaSO ₄ · 0.5H ₂ O, expanded mineral powder and an air-entraining additive, acid loam is additionally introduced, the clay is taken half-acid with an Al ₂ O ₃ content _of at least 20 wt. .%, including pyritized, containing sulfate and sulfite impurities (more than 2% in terms of SO ₃ ^-2 ion), and vermiculite sand of a fraction of 0-1.25 mm was taken as expanded mineral powder, they are introduced as an air-entraining additive liquid silicate glass with a density of 1300 kg / m ³ , in the following ratio of all components, wt.%:

- loam 18-50; semi-acid specified clay, including including substandard pyritized 28-42; semi-aquatic gypsum 20.5-37; expanded vermiculite fr. 0-1.25 mm 1.5-3; silicate glass with a density of 1.3 g / cm over 100% dry mix 0.2-0.5

Characterization of mass components

1. Acidic loam of the Obidim deposit (Tula region):

- moderately ductile (ductility number 11.8-12.9);

- non-sintering, fusible clay raw materials;

- the strength of the shard of loam, with a firing temperature of 1000 ° C 15-17 MPa, redburning.

Chemical composition, wt.%: SiO ₂ - 71.16-72.43; Al ₂ O ₃ + TiO ₂ - 10.08-12.15; Fe ₂ O ₃ - 4.91-5.83; CaO - 1.86-2.40; MgO - 0.71-1.4; SO ₃ - 0.01-0.04; P.P.P. - 7.74-9.28.

2. Semi-acid fusible clay pyritized. (Kukuevsky field of the Tula region)

Table 1 The chemical composition of clay pyritized raw materials Chemical composition (oxides) Requirements OST 21-78-88 for chemical composition,% Clay Kukuevskaya pyritized,% - Al ₂ O ₃ > 7 22.45 - Fe ₂ O ₃ + FeO <14 5.3 - CaO + MgO <20 3.39 - sulfate and sulfide-containing impurities in terms of ion SO ₃ ^-2 <2 3.19 - Na ₂ O + K ₂ O <7 2.26 - SiO ₂ <85 53.7 - loss on ignition rest

As can be seen from the chemical composition, the clay of the Kukuevskoye deposit does not correspond to OST 21-78-88 in terms of the content of sulfate and sulfite-containing impurities (> 2% in terms of SO ₃ ^-2 ion), i.e. for wall ceramics are substandard. Contains> 20% Al ₂ O ₃ , is medium plastic. Refractoriness 1280-1290 ° C, i.e. is fusible. Pyrite in terms of ion SO ₃ ^-2 contains (> 2%), therefore, is pyritized. A ceramic crock burnt at a temperature of 1000 ° C has a strength of 42 MPa, while in accepted loams the strength of a crock is 15-17 MPa. Therefore, such clay is added to loams to increase the strength of ceramics.

Instead of pyritized clay, expanded clay clay containing at least 20% Al ₂ O ₃ can be taken.

3. Bentonite semi-acid clay. High plasticity (plasticity number 32-35), fusible. The chemical composition includes wt.%: SiO ₂ - 54; Al ₂ O ₃ - 17.5 (half-acid); TiO ₂ 0.6; Fe ₂ O ₃ 6.9; CaO - 2.6; MgO - 2.7; K ₂ O - 2.7; SO ₃ - 0.9; PPP - the rest.

Due to its high ductility and low content of sulfur compounds, such clay is recommended for heat-insulating products, i.e. Designed for mass prototype.

4. The semi-acid refractory clay of the Lukoshinsky deposit. Meets the requirements of TU RSFSR-434-84. The plasticity number is 15-20. Refractoriness 1430-1570 ° С. Chemical composition, wt.%: SiO ₂ - 61-63; Al ₂ O ₃ - 20-27; Fe ₂ O ₃ - 2-3; CaO - 1.5-1.7; MgO - 0.5-0.7; Na ₂ O + KL ₂ O - 2.1-2.5; P.P.P. - 7-8%.

5. Semi-aquatic building gypsum - β-CaSO ₄ · 0.5H ₂ O, produced in the city of Novomoskovsk, Tula region.

Basic properties:

Brand G4. Bulk density 650 kg / m ³ . Normal density is 49-50%. Start setting 6 minutes, end setting 12 minutes. The compressive strength of 4.2 MPa, and in the dry state 11-12 MPa.

The chemical composition includes, wt.%: Β-CaSO ₄ · 0.5H ₂ O - 89.1; CaCO ₃ - 9.1; SiO ₂ - 1-8.

6. Liquid glass (sodium).

The chemical composition includes, wt.%: SiO ₂ - 30.0; Al ₂ O ₃ - 0.06; Fe ₂ O ₃ - 0.01; CaO - 0.02; SO ₃ - 0.15; Na ₂ O - 12; PPP - the rest.

Accepted liquid glass with a density of 1300 kg / m.

7. Swollen vermiculite. Particles of fraction 0-1.25 mm were accepted.

The chemical composition includes: (K ₂ O) Al ₂ O ₃ · SiO ₆ (MgO) ₆ · O ₂₀ (OH) ₄ . Bulk density 180-200 kg / m ³ . Meets the requirements of GOST 12865-67 "Expanded Vermiculite."

8. Expanded perlite sand - accepted for properties identical to vermiculite sand, ie fractions 0-1.25. Bulk density 200 kg / m ³ (for the prototype).

table 2 The compositions of ceramic masses Mass components Numbers and compositions of the mass, wt.% one* 2 3 four 5 6 7 8 one 2 3 four 5 6 7 8 9 1. Sour loam fifty fifty 45 32 thirty eighteen fifteen - 2. Semi-acidic clays containing at least 20% Al ₂ O ₃ 2.1. Pyrified Kukuev Clay - 28 - 31 - 42 44 - 2.2. Semi-acid refractory clay of the Lukoshinsky deposit - - eighteen - 31 - - - 3. Bentonite highly plastic (Al ₂ O ₃ - 17.5%) 28 - - - - - 45 4. Semi-aquatic gypsum β-CaSO ₄ · 0.5H ₂ O 20.5 20.5 35.25 35 36.5 37 38 10 5. Expanded vermiculite reclaimer fr. 0-1.25 mm 1,5 1,5 1.75 2 2.5 3 3.0 - 6. Expanded perlite sand fr. 0-1.25 mm - - - - - - - 45

one 2 3 four 5 6 7 8 9 7. Air entraining additive in excess of 100% dry mix 7.1. Liquid glass with a density of 1300 kg / m ³ (over 100%) 0.5 0.5 0.45 0.3 0.2 0.2 0.1 - 7.2. PO-6 (over 100%) - - - - - - - 7 Note: * compositions No. 1 and No. 2 are beyond the limits.

Experiments on the implementation of the task

Experience 1. Dosed by weight of 560 g (28%) (composition No. 2, table 2) of pyritized substandard dry clay, which was dissolved in water taken in the amount of 1120 g (W / T = 2). The resulting slurry was passed through a sieve of 400 holes / cm ² to separate particles of pyrite Fe ₂ S fractions of more than 0.3 mm on the grid (see the article by L.S. tiles for floors. "- M: Abstracts of VNIIESM. Ceramic industry. Issue No. 1. - 1979. - p.14-16), and also carried out the separation of pyrite particles using a portable electromagnet.

Loam was added to the slurry, passed through a 1.0 mm roll gap (to exclude carbonate inclusions and to prevent a muffin defect). A slurry of two clays was mixed for two minutes, while mixing for 1.5 minutes, a mixture of semi-aquatic gypsum 410 g (20.5%) with vermiculite 30 g (1.5%), as well as 10 g (0.5) were added. %) (in excess of 100% dry mix) of liquid glass with a density of 1.3 g / cm ³ . The resulting slip in a thick sour cream with a water-hard ratio B / T = 0.56 was poured into molds with a size of 16 × 4 × 4 cm with short-term vibration (10-15 seconds) to smooth the surface and fill the corners of the mold. After 15 minutes, the molds were redistributed and (without pallets) dried at a temperature of 150-180 ° C for 10 hours, and then fired in a factory ring furnace together with a ceramic brick at a temperature of t _max = 1000 ° C.

A day later, ceramic samples made from the composition of the mixture No. 2 (table 2) were tested for the indication of average density, strength and water absorption. The color of the ceramics was perceived visually.

In a similar way, all ceramic samples were made from mixtures No. 1; 3; four; 5; 6; 7, including samples from the composition of the mass of the prototype No. 8. The test results are shown in table 3.

Table 3 Properties of ceramic samples Properties Unit of Change Number of masses, corresponding ceramic samples and property parameters one* 2 3 four 5 6 7 Prototype 8 Average density kg / m ³ 1450 1400 1348 1200 1250 1190 - 298 Strength at - bend MPa 4.2 5,6 4.82 3.6 2,8 1.9 - 0.3 - compression MPa 12.3 15.1 14.2 12.1 12.8 10,4 Collapsed 0.75 Color red cream. cream. light cream light cream light cream - red The presence of efflorescence there is no no no no no no there is Note: * compositions No. 1 and No. 7 are prohibitive, since the composition of mass No. 1 has an average density of samples higher than the density of conventionally effective ceramics (more than 1.4 g / cm ³ ), and the strength is less than that of samples of composition No. 2 from a similar by the quantitative composition of the components, but with the use of a semi-acid bentonite clay containing Al ₂ O ₃ less than 20%, efflorescences appear on the red surface.

Ceramic samples from composition No. 7 collapsed from the increased content of pyritized clay (44 wt.% And increased gas evolution due to exceeding the norm of semi-aquatic gypsum (over 42%)).

Analysis and conclusions of the test results of the properties of ceramic samples are shown in table 3.

1. The density of porous ceramics exceeds the density of the known 3.9-4.6 times.

2. Compression strength - 20 times.

3. Products have a high architectural appearance, as they do not have efflorescence on a light surface tone (cream, light cream).

4. Samples of ceramics from mass No. 2; 3; 5 correspond to class 1.4 in accordance with GOST 530-2007 and relate to conditionally effective ceramics, moreover porous-solid, and samples from mass No. 4 and No. 6 are effective (class in average density 1.2), i.e. average density not more than 1200 kg / m ³ .

Thus, the task of obtaining mass for a conditionally effective full-bodied ceramic brick (class 1.4) with a density of not more than 1400 kg / m ³ , an effective class of 1.2 with increased architectural expressiveness, a strength mark of at least M100 for brick and not less than M35 for corpulent stones achieved. The physico-chemical essence of achieving this goal is as follows.

1. In the composition of the mass (before firing), the role of a binder is played by semi-aquatic gypsum, and all other components play the role of a filler, each of which performs a certain function in the drying and firing process.

2. In the firing process, on the contrary, the clay component played the role of the ligament, and the semi-aquatic gypsum performs a number of the following functions.

2.1. The role of the porizer is more effective than carbonate-containing additives, since the molecular mass of gases is CO ₂ = 60 and SO ₂ = 80, that is, on the same path of exit of these gases from the mass of fired ceramics according to Newton’s second law F = ma , the force of SO ₂ gases is higher than that of CO ₂ gas. In addition, for the release of SO ₂ gases, free channels are created due to the preliminary allocation of chemically bound water:

.

.

2.2. The role of floodplain, due to the formation of CaO and, accordingly, the formation of the glass phase CaSiO ₃ , at t = 1000 ° C, feldspar can be formed - anorthite CaO · Al ₂ O ₃ · SiO ₂ having a crystalline structure. Thus, semi-aquatic gypsum, on the one hand, reduces the average density by porization, and on the other hand, increases strength.

2.3. The role of the bleach that converts red-burning clays into cross-burning ones, therefore, the appearance of high formations on the cream and light cream surfaces of wall ceramics is excluded.

The increased amount of semi-aquatic gypsum in the composition of the mass is 2-3 times more, compared with the composition of the prototype, contributes to:

3.1. the increase in strength formed by casting the semi-finished product, which makes it possible to dry raw brick without pallets, and in a state such as shrinkage;

3.2. increased crack resistance during drying, since internal stress is eliminated by compensating for the shrinkage of the clay component by expanding the gypsum component during hardening;

3.3. the term for the end of setting of the mass in the molds is reduced and, accordingly, the frequency of turnover of molds for the next filling with slip mass increases;

4. Expanded vermiculite in the state of the dust fraction (less than 1.25 mm) plays the role of a thinner additive in the drying process, and also helps to increase architectural expressiveness, frost resistance, heat resistance and lower average density.

5. Soluble glass acts as an air-entraining component, an electrolyte, and an alkali-containing melt that increases strength.

Economic feasibility in comparison with the composition of the mass of the prototype.

1. The consumption of expensive filler (scrubber) - expanded vermiculite is reduced by 15 times, moreover, with the provision for the disposal of the dust fraction (less than 0.16 mm) from electrostatic precipitators. This reduction allows you to compensate for the greater consumption in the claimed composition of semi-aquatic gypsum (in the prototype 10 wt.%, In the claimed composition of 20.5-37 wt.%, Which is 2-3.7 times more).

2. It is possible to increase the productivity of dryers, by eliminating pallets, and the possibility of drying in a stacked state and also reduces the cost of heat for evaporation of water.

3. It is possible to burn products together with ceramic bricks obtained by the traditional molding method.

4. The opportunity is provided for the use (utilization) of pyritized clays and dust fraction of vermiculite.

5. The scope of ceramic products in construction is expanding, due to the possession of self-supporting ceramics in building envelopes.

6. Due to the separation of pyrite from the slurry of pyritized clay by the sieve method and a portable electromagnet, the environmental situation in the firing workshop and the environment (outside the workshop) are improved, since the release of SO ₂ gas into the workshop and the atmosphere is prevented.

7. Retained pyrite is envisaged to be realized in the production of sulfuric acid and, thereby, sent for secondary use.

6. Based on the advantages specified in paragraphs 1-7, the cost of ceramic wall products is reduced by 20-25% with respect to the prototype.

Claims (1)

The composition of the mass for wall ceramics, including clay, semi-aquatic gypsum β-CaSO ₄ · 0.5H ₂ O, expanded mineral powder and an air-entraining additive, characterized in that they use semi-acid clay with an Al ₂ O ₃ content _of more than 20 wt.%, Including including pyritized, containing sulfate and sulfite impurities (more than 2% in terms of SO ₃ ^-2 ion), expanded vermiculite of a fraction of 0-1.25 mm is used as expanded mineral powder, and liquid silicate glass with a density of 1 is used as an air-entraining additive , 3 g / cm ³ , and additional but contains acidic loam, in the following ratio of components, wt.%:
sour loam 18-50 indicated clay 28-42 semi-aquatic gypsum 20,5-37 expanded vermiculite 1,5-3 silicate glass, in excess of 100% dry mix 0.2-0.5