RU2300507C1 - Ceramic mass - Google Patents

Abstract

FIELD: building industry; building materials industry; chemical industry; production of the compositions of the ceramic masses for manufacture of the wall building components.

SUBSTANCE: the invention is pertaining to the compositions of the ceramic masses for manufacture of the wall building products, predominantly the bricks and can be used in the industry of building materials. The technical result of the invention is the increased strength, the architectural expressiveness and the decreased degree of the general shrinkage. The indicated technical result is reached due to the fact, that the ceramic mass contains the clay loam, the combustible additive, the ferrous-containing production waste and the clay aggregate swelling clay. As the combustible additive the ceramic mass contains the "scop" - the sediment of the waste waters from the chemical treatment of the industrial wastes of production of the paperboard, and as the ferrous-containing wastes they use the sediment from the cyclones of the purification of the surfaces of the steel constructions or the details by the shot-blast machine at following components ratio( in the volumetric %): clay loam - 64-66; the combustible addition - 6-9; the ferrous-containing waste - the finely-disperse sediment from the cyclones after purification of the steel details separators from a skinning of steel details and designs surfaces by the shot-blasting apparatus - 7-13; the ceramsite swelling clay - 15-20.

EFFECT: the invention ensures the increased strength, the architectural expressiveness and the decreased degree of the general shrinkage.

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Description

The invention relates to compositions of ceramic masses for the manufacture of wall building products, mainly bricks, and can be used in the building materials industry.

Known ceramic mass, including clay raw materials, fading components (coal, sawdust), barite weighting agent and iron-containing waste of steel wire production in the following ratio of all components, wt.%:

clay 83-87 sawdust 4-5 coal 2.5-3.5 barite weighting agent 4-5 iron waste steel wire production 2.5-3.5

(See the Author's certificate of the Russian Federation No. 2083526, MKI ³ C 04 B 33/00, published 1997).

Along with the great advantages of the known composition (water absorption is reduced, a beautiful architectural appearance is achieved), there are also disadvantages, specifically:

1. Sophisticated technology for the preparation of molding material, because barite weighting agent and iron-containing waste of steel wire production must be preliminarily ground in mills to a finely dispersed state. Otherwise, defects (smelting, "fly") will form on the surface of the products, which is not allowed for face bricks.

2. Insufficient strength of dried bricks (scrap is increased due to half-timber). The latter contributes to the barite weighting agent.

3. An increased degree of carbonization inside the brick (dark areas), including the appearance of individual dark spots on the front surface. The latter is promoted by organic burnable additives (coal and sawdust).

The closest composition of the ceramic mass in terms of the quality and technical solution is given in the article by A.I. Efimov, "The Use of Iron-Containing Wastes in the Production of Ceramic Brick". 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).

The known composition contains components in the following ratio, vol.%:

loam 70 wood sawdust eighteen iron containing sludge - waste aniline-dye production 12

Known composition has the following advantages:

1. Two types of waste are utilized at once (sawdust and iron-containing sludge).

2. Iron-containing sludge does not require pre-treatment.

3. The relatively low density of the brick 1630-1650 kg / m ³ .

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 M 125 and above.

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. The ecology of the surrounding air is disturbed in the drying shop, since the smell is not quite pleasant, inherent in aniline dyes.

4. The production technology is becoming more complicated, since the sludge is pre-dried.

The objective of the invention is to increase the strength, architectural expressiveness and reduce the degree of general shrinkage.

To accomplish the task, the ceramic mass includes clay loam, a burnable additive, and iron-containing production waste, characterized in that it contains “oskop” as a burn-out additive — sewage sludge from chemical treatment of cardboard waste, and sludge is taken as iron-containing waste from cleaning the surface of steel structures or parts with a shot blasting machine and expanded clay expanded clay was additionally introduced in the following ratio of all components, vol.%:

loam 64-66 burnable additive 6-9 iron-containing waste - fine sediment from cyclones from surface cleaning steel parts and structures shot blasting apparatus 7-13 expanded clay expanded clay 15-20

Tests were conducted where components with the following characteristic properties were used.

1. Loam of the Osinogorsk deposit (Tula region). According to the particle size distribution I, the loam layer is characterized by the composition: clay particles 10%, sand 60%, dusty 30%. Loam II layer is characterized by composition: clay particles 6%, sand particles 40%, dusty 55%. Raw materials are low in the number of coarse inclusions with a predominance of small sandy-stony and carbonate inclusions. This raw material belongs to the group of "sour". Loams are non-sintering, low melting, moderately plastic raw materials (plasticity number 10–13), with the exception of the second layer, it is low plastic (plasticity number 3-5). Loam water absorption of 13%, compressive strength of 81-134 kg / cm ² , with a bend of 29-44 kg / cm ² (at a temperature of 950-1000 ° C). The color after firing is red.

According to the chemical composition, the loams are characterized by the following component content,%: SiO ₂ 68.21-78.5, AI ₂ O ₃ 8.89-13.95, Fe ₂ O ₃ 3.24-5.47, CaO 0.65- 2.85, MgO 0.6-1.7, SO ₃ 0.02-0.18, Na ₂ O 0.57-1.06, K ₂ O 1.72-2.92, TiO ₂ 0.1 -0.2, pp. 3.11-5.34.

2. The burn-out additive is “osprey” sewage sludge from the chemical treatment of cardboard waste with organic acids such as citric acid. Has a high humidity of 60-80%. In dry condition it has the following properties:

- average density - 420-470 kg / m ³ ;

- the proportion in the sludge of dry osprey is - 20-40%.

Table 1 - Chemical composition of osprey. The content of oxides, wt.% one 2 3 four 5 6 7 SiO ₂ Al ₂ O ₃ Cao MgO Fe ₂ About ₃ T _i O ₂ RFP 26-30 17-20 0.15-0.18 0.6-0.2 0.1-0.3 0.05-0.1 rest Table 2 - the Material composition of the osprey The name of the substances that make up the mineral residue of osprey, before its combustion Sample Number Average value one 2 3 one 2 3 four 5 Cellulose fiber 51 55 fifty 52 Kaolin 46.7 41.9 47.9 45.5 Impurities (rosin, organic acids) 2,3 3,1 2.1 2,5

Based on the data in Table 2, the burn-out additive is a cellulose-fibrous organomineral substance, that is, it is a composite production waste. The reason for the oversized average density of the osprey is the presence in its material composition of aluminosilicate substance (kaolin).

3. Iron-containing waste is iron-containing dust that settles in cyclones. Such dust is formed when cleaning the surfaces of steel industrial valves (for example, valves of gas pipelines, etc.). A shot with a diameter of less than 2 mm along with a stream of air is sent by the apparatus to the steel surface of the parts, and under high pressure. Under the action of shot blows, the surface of steel or cast-iron parts becomes smooth, shiny. The resulting iron dust settles in cyclones. Particles of a flask consisting of clay and quartz ground sand are also removed from the surface.

The composition contains at least 50% (Fe + Fe ₂ O ₃ + FeO). The rest is aluminosilicate dust (Al ₂ O ₃ + SiO ₂ ) from the flask. Before use, the precipitate from cyclones is sieved through a sieve with a mesh diameter of 0.315 mm. Granules of steel shot are retained on the sieve, and the sifted component is introduced into the molding ceramic mass. Part of the erased microparticles from steel balls (fractions) falls into the composition of the specified additives. The specific surface of dust from cyclones is 120-140 m ² / kg.

4. Expanded clay expanded clay is a highly dispersed clay, the composition of which is dominated by small parts (less than 0.001 mm), and their amount varies from 35 to 83%. Clay is slightly calcareous, medium plastic, the plasticity number 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 coefficient of expansion is relatively small, varies from 2.5 to 5.0. The temperature of the beginning of the expansion of 1000-1150 ° C. Water absorption ranges from 3% to 7%. The compressive strength is 36–40 MPa.

The method of obtaining the ceramic mass is as follows: experiments were carried out to realize the composition of the ceramic mass using components taken by volume indicated in table 3. In total, five batches of molding masses were prepared. First, the osprey was dried to a moisture content of 60%. The obtained wet scum sludge was mixed with dry finely dispersed pre-sieved through a sieve with a hole diameter of 0.315 mm iron-containing loose sediment taken from a cyclone. The resulting semi-dry mixture was mixed with a volume-dosed powder consisting of two clays — loam and expanded clay (clay particle diameter less than 2 mm). The mixture of semi-dry powders was moistened with water to a molding moisture content of 20%. From the obtained plastic mass, samples 50 × 50 × 50 mm in size were molded (manually) under a specific pressure of 2.5 MPa, followed by drying at a maximum temperature of 75 ± 5 ° C for 72 hours, and then fired in a ring factory furnace at t _max = 1000 ° C. After firing, they were tested for strength and architectural appearance (see table 4).

Table 3 - the composition of the ceramic mass No. Mass components (dry) The numbers of the experimental masses and their compositions Prototype% by p / p one 2 3 four 5 volume one. Loam 68 66 65 64 64 70 2. Burnout additive: 2.1. Osprey (on a dry component) 5,6 6 8 9 9.5 2.2. Sawdust - - - - - eighteen 3. Iron-containing sludge (dry) - aniline-ink waste production - - - - - 12 Iron-containing waste - finely divided (dry) sludge from four. cyclones from cleaning the surface of steel structures, parts by shot blasting apparatus 12,4 13 9 7 6 5. Expanded clay expanded clay fourteen fifteen eighteen twenty 20.5 - Note: compositions No. 1 and No. 5 are prohibitive.

Table 4 - Properties of wall ceramic samples No. The properties Numbers of experimental masses and parameter values Prototype one 2 3 four 5 one. The limit of compressive strength, MPa 30,2 31.5 24.2 20.7 17.1 18.7 2. Color after firing Red Light red with an orange tint Dark red with dark spots from carbonization 3. Shrinkage: 3.1. Air (after drying) 8.0 8.12 8.75 9.00 9.27 8.6 3.2. Total 8.8 8.5 8.2 8.0 7.8 12,4

Note: compositions No. 1 and No. 5 are not recommended for implementation at the plant, since composition No. 1 does not achieve an architectural appearance, and for composition No. 5, the strength is lower than that of the known composition (prototype).

As can be seen from table No. 4, the composition of the proposed ceramic mass corresponding to mixtures No. 2; 3; 4 (see table 3), meets the goal, since in comparison with the prototype is observed:

a) strength increases by 2-12.8 MPa (or 16-68%);

c) architectural expressiveness is increased due to the acquisition of lighter tones with an orange tint and the exclusion of high formations;

c) fire shrinkage is almost completely eliminated, and consequently, the degree of general shrinkage is also reduced (by 32-36%).

The physicochemical essence of achieving the goal is explained by the combination of the positive effect on the loam of all three additives specifically:

1. “Skop” plays the role of not only a burn-out additive, due to the combustion of the cellulosic component, but also contributes to crack resistance during drying, since cellulose fibers inhibit the process of rapid evaporation of moisture in the first (dangerous) period of heating of ceramic raw material. Ultimately, this has a positive effect on the strength of burnt bricks. "Osprey" is more lyophilic in comparison with the wood sawdust contained in the composition. In addition, the “osprey” contains 60-70% white ash, consisting of metakaolinite Al ₂ O ₃ · 2SiO ₂ , which, as you know, goes into mullite 3Al ₂ O ₃ · 2SiO ₂ amorphous silica in accordance with the decomposition reaction:

Mullite increases strength, and amorphous silica binds soluble salts of alkali and alkaline earth metals into insoluble silicates (see Frost Technology of building ceramics. - Kiev. Vishka school 1980. - 384 p., Specifically p. 144 above.)

For example: a) Ca ₂ SO ₄ + SiO ₂ = Ca ₂ SiO ₃ + SO ₃ ↑

b) Na ₂ SO ₄ + SiO ₄ = Na ₂ SiO ₃ + SO ₃ ↑

The formation of a glass phase enhances strength and prevents the formation of light spots on the surface of ceramics, and the white color of the ash from the combustion of osprey helps the red-burning loams to acquire light colors after firing.

So, ash from the "osprey" helps to increase strength, message light tone and reduce the degree of salinization.

2. Iron-containing waste, introduced with dust from cyclones from cleaning the surface of steel parts or structures, simultaneously plays the role of flux, since it contains at least 50% Fe ₂ O ₃ , and the role of a thinning additive, since the rest (up to 100%) falls on the proportion of aluminosilicate component (heat-treated flask consisting of clay and silica). All meadows, including Fe ₂ O ₃ , increase the strength of loams due to the formation of a glass phase consisting of fayalite - FeSiO ₃ . Glass phase, as you know, binds crystalline minerals such as mullite into a strong conglomerate. The amount of Fe ₂ O ₂ in the composition of the accepted loams% is additionally replenished with the introduction of expanded clay expanded clay containing 1.5-2 times more of this oxide in comparison with loams.

It should be noted that the novelty of increasing the strength of ceramic products lies not only in the action of Fe ₂ O ₂ melt, but also in the reinforcing action of steel microparticles, that is, the proposed composition of the ceramic mass makes it possible to obtain a dispersed ceramic composite reinforced with microparticles of steel.

3. Expanded clay contributes to an increase in strength, since it is half acid, and the accepted loams are acidic, that is, not only the amount of melt - Fe ₂ O ₂ , but also Al ₂ O ₃ , and, therefore, the amount of the main mullite mineral increase in the loam. In addition, this clay also contributes to an increase in crack resistance during drying of the raw material, since it is more plastic than loam. It has been established by science and practice that the addition of more plastic clays to less plastic loams contributes to the tensile strength in the process of drying raw brick, which counteracts shrinkage stresses (see K. Nakhrotyan, Drying and firing in the construction ceramics industry. - M.: Stroyizdat , 1962. - 604 p.).

Ultimately, this also helps to increase the strength of the calcined products. Due to expanded clay clay, fire shrinkage is almost eliminated, and therefore, the degree of general shrinkage is reduced, but not so much that the size of the bricks established by GOST 530-95 "Ceramic bricks and stones" increases. This process is regulated by the established rate of addition of this clay in the composition of the mass, i.e. is in the proposed composition within 15-20% of dry weight. The decrease in the degree of general shrinkage is explained by one factor - a sign of the onset of expanded clay clay expansion at a brick firing temperature (1000 ° C). The color of this clay after firing is light brown. The combination of colors red from burnt loams, white from osprey and light brown from expanded clay clay gives light red color to ceramic with an orange tint.

4. Economic feasibility in comparison with the prototype is as follows:

4.1. Based on the proposed composition, it is possible to produce not only ordinary wall, but also front bricks, which have a higher selling price (20-25% higher).

4.2. "Skop" and iron-containing fine particles do not require additional processing, and the iron-containing slurry of the prototype is pre-dried, which is associated with heat and energy consumption.

4.3. Decreases by 10-15% rejects when drying raw.

4.4. The burn-out additive in the composition of the prototype - (wood) sawdust is among the expensive waste, as other building materials such as wood concrete, fiberboard and others are made on their basis. "Skop" in the composition of the proposed structure is ten times cheaper than sawdust, and also occupies the area of agricultural land, i.e. there is a osprey disposal aimed at protecting the environment.

4.5. The consumption of molding material is reduced (saved) by reducing the overall shrinkage of prefabricated bricks.

4.6. Two underutilized wastes are disposed of.

Conclusion: based on clause 4.1.-4.6. the cost of wall ceramic products from the proposed mass composition is 15-20% lower in comparison with the products of the prototype.

Claims (1)

Ceramic mass, including loam, a burn-out additive, an iron-containing production waste, characterized in that it contains a “osprey” as a burn-out additive - sewage sludge from chemical treatment of cardboard production waste, and a precipitate from cyclones from cleaning steel surfaces is taken as iron-containing waste structures or parts with a shot blasting machine and expanded clay expanded clay was additionally introduced, with the following ratio of all components, vol.%: Loam 64-66 Burnout Additive 6-9 iron waste - fine precipitate from cyclones from cleaning the surface of steel parts and designs by shot blasting apparatus 7-13 Expanded clay expanded clay 15-20