RU2150441C1 - Roasting-free refractory material - Google Patents

Abstract

FIELD: refractories industry, more particularly manufacture of refractory products for lining of heat assemblies operating at temperature up to 1400 C. SUBSTANCE: roasting-free refractory material comprises as hydrotation components, binding agent, lime and tripoli, as ceramic structure forming components, spent sulfur production catalyst and pyrite cinders and as filler fireclay having fractions, wt.%; 0-0.63 mm fractions, 25; 0.63-1.25 mm fractions, 12.5; 1.25-2.5 mm fractions, 62.5; ratio of components is as follows, wt. %; spent sulfur production catalyst, 20.0-22.1; pyrite cinders, 5.3-6.8; tripoli, 5.6-7.2; lime, 6.0-6.68; fireclay, 57.5-62.5. EFFECT: reduced pressing pressure, lower price and no ecological problems are involved, since two types of large tonnage waste products are utilized. 3 tbl

Description

The invention relates to the refractory industry and can be used in the manufacture of refractory products for lining thermal units with operating temperatures up to 1400 ^o C.

Known non-fired refractory / Ilyina N.V. Lining rotary kilns of the cement industry. - M .: Stroyizdat, 1967. - S. 46./ [1] from clinker-cement concrete, including, by weight. %:
Portland cement clinker - 50 - 67
Portland cement - 33-50
The main disadvantages are:
slow hardening speed;
a sharp decrease in strength at operating temperatures;
low thermal stability (one heat exchange 1300 ^o C - water);
the composition is expensive, consisting of clinker components.

Also known is the raw material mixture for the manufacture of refractory concrete / a.s. USSR N 1077860, M.C. From 04 to 35/66, 28/06. Raw mix for the manufacture of refractory concrete / Shpolyansky M.A., Wack E.G. and others. - Publ. 06/30/87. - Bull. N 24, 1987 // Discoveries. Inventions. / [2], in which the role of a hydraulic binder is performed by calcium aluminates. The raw material mixture has the following composition, wt.%:
The waste of the catalyst carrier of the conversion of natural gas - 60 - 80
Calcium Aluminates - 20 - 40
This composition of the binder and aggregate provides a set of strength in a shorter time than from clinker-cement concrete, and the predominance of Al ₂ O ₃ in the composition is a fairly high temperature of application.

 However, this composition has its drawbacks. The main disadvantage is a significant, almost two-fold, decrease in strength after firing. This effect is explained by the destruction, starting with dehydration, of a cement stone consisting of calcium hydroaluminates. In addition, the composition is expensive, requiring a scarce clinker component - specially made clinker calcium aluminates.

 As a part of / Arbuzova T.E., Sukhov V.Yu., Ryabova M.V. Technology of composite pressed materials for general construction and special purposes. - Building materials, N 8, 1998. - S. 10-12./ [3] some of these shortcomings are missing. The composition of the binder includes non-deficient components: lime and flask. High temperature firing is not required for binder preparation. A significant set of strength occurs already during the pressing of products due to contact condensation hardening. However, such a composition cannot be used for lining thermal units due to the destruction of cement stone that occurs when heated.

 Known refractory mass / a.s. USSR N 1502534, M.C. From 04 to 33/22. Refractory mass / Suvorov S.A., Makarov V.N. and others. - Publ. 08/23/89. - Bull. N 31, 1989 // Discoveries. Inventions. / [4] contains some components similar to the claimed composition, namely: a spent sulfur production catalyst and chamotte aggregate. However, it is different in composition, ratio of components, technical nature and the achieved result from the claimed one: the products after molding do not have mounting strength, they must be fired before use, like well-known piece refractories.

The closest in technical essence and the achieved result is the composition of non-fired refractory (prototype) / RF Patent N 2016875, M.Kl. From 04 to 35/00. Non-fired refractory / Perepelitsin V.A., Sprygin A.I. and others. - Publ. 07/30/94. - Bull. N 14, 1994 // Discoveries. Inventions. / [5], including:
Tricalcium silicate - 35 - 60
Four-calcium aluminoferrite - 2 - 5
Periclase - 10 - 18
Magnesian Spinelid - 3 - 6
Dicalcium Silicate - Else
The non-fired refractory is produced by mixing the raw materials, mixing the resulting mixture with water, pressing the products and holding the pressed products in air, after which the products are ready for use. The tetra-calcium aluminoferrite and tricalcium silicate contained in the refractory provide intensive formation of a hydration and ceramic structure, while periclase and magnesia spinel are highly refractory fillers. Hydration components contribute to obtaining significant strength after hardening, and sintering during heat treatment to maintain a significant part of the gained strength.

The disadvantages of this composition are:
low relative strength at operating temperatures (compared to the original after hardening);
the composition is expensive, requiring scarce materials.

 The technical result of the invention is to increase the residual strength at operating temperatures, increase thermal stability, reduce production costs, and also utilize industrial waste.

 The technical result in the invention is achieved by the fact that lime and tripoli are used as hydration components of the binder, spent catalyst for sulfur production and pyrite cinders are used as components forming the ceramic structure, and chamotte of fractional composition, wt.%: Fraction 0 ... 0.63 mm - 25; fractions of 0.63 ... 1.25 mm - 12.5; fractions 1.25 ... 2.5 mm - 62.5; in the following ratio of components, wt. %: spent sulfur production catalyst 20.0 - 22.1; pyrite cinders 5.3-6.8; Tripoli 5.6 - 7.2; lime 6.0-6.68; fireclay 57.5 - 62.5.

Spent sulfur production catalyst - 20.0 - 22.1
Pyrite cinders - 5.3 - 6.8
Tripoli - 5.6 - 7.2
Lime - 6.0 - 6.68
Fireclay - 57.5 - 62.5
The spent sulfur production catalyst consists of rounded granules with a diameter of 3 - 7 mm with a specific surface area of 100 - 125 m ² / g and consists of 95 - 97% of the chemically active component γ-Al ₂ O ₃ . Impurities contain sulfur, sulfates and carbon / Menkovsky M.A., Yavorsky V.G. Sulfur technology. - M.: Chemistry, 1985. - 328 p. / [6].

 Pyrite cinder is formed during the burning of flotation pyrites in fluidized bed furnaces. The main component is iron oxide. Silica and iron oxide are present in the impurities.

 Tripoli is a beige-gray friable rock, consisting of amorphous silica with inclusions of glandular opoka fragments.

 Calcium quicklime, lump.

 Fireclay is obtained by roasting clay and subsequent crushing.

 The increase in strength after molding products made of ceramic concrete is achieved due to the presence of lime and tripoli in the composition, providing contact condensation hardening during pressing / Arbuzova T.E., Sukhov V.Yu., Ryabova M.V. Technology of composite pressed materials for general construction and special purposes . - Building materials, N 8, 1998. - S. 10-12. / [3].

 The increase in the strength of ceramic products after firing was obtained through targeted processes of solid-phase sintering of the binder, in which the active form of alumina forms a continuous series of solid solutions with additives in a wide temperature range, and other strengthening compounds between the charge components are formed.

Known / State diagrams of silicate systems: Reference. Vol. 2. Metal-oxygen compounds of silicate systems / Toropov N.A., Barzakovsky V.P. and others. - Leningrad: Science, Leningrad. Otdel., 1970. - P. 18-34./ [7] that the increased activity of γ-Al ₂ O ₃ to chemical interaction with other components is manifested up to 940 ^o C, and moderate - up to 1200 ^o C, that is, to a temperature transition to α-Al ₂ O ₃ .

/Диаграммы состояния силикатных систем: Справочник. Вып. 1. Двойные системы / Торопов Н. А. , Барзаковский В.П. и др. - Ленинград: Наука, Ленинград, отд., 1970. - С. 151-153/ [9];

Подбор гранулометрического состава заполнителя производился с условием получения смеси, обладающей максимальной плотностью, чтобы уменьшить усадочные деформации при термообработке. Такими свойствами обладает смесь следующих фракций, мас.%: фр. 1,25...2,5 - 62,5: фр. 0,63...1,25 - 12,5; фр. < 0,63 - 25.Acceleration of sintering of alumina is observed in the presence of additives capable of forming solid solutions in alumina / Kukolev G.V., Leve E.N. The influence of the production method and the degree of dispersion of alumina on its sintering ability in the presence of various additives. - Journal of practical chemistry. T. XXVIII, N 9, 1955. - S. 909-915./ [8]. These additives include Fe ₂ O ₃ . The temperature at which the formation of a solid solution based on Al ₂ O ₃ in the Al ₂ O ₃ - Fe ₂ O ₃ system begins at about 900 ^o C. With increasing temperature up to 1400 ^o C, the amount of iron oxide in the composition of the solid solution increases / State diagrams of silicate systems: Reference . Vol. 1. Binary systems / Toropov N.A., Barzakovsky V.P. et al. - Leningrad: Science, Leningrad, Dep., 1970. S. 257-260./ [9]. The ratio between the components of the binder (lime, tripoli, spent catalyst for sulfur production and pyrite cinder) in the proposed composition is selected taking into account the following provisions:
1) the ratio between lime and tripoli is taken optimal for the manifestation of contact-condensation properties / Arbuzova T.E., Sukhov V.Yu., Ryabova M.V. Technology of composite pressed materials for general construction and special purposes. - Building materials, N 8, 1998. - S. 10-12 / [3];
2) the total amount of lime and tripoli taken is the minimum to ensure the transport strength of the products after molding;
3) the ratio between the spent catalyst and pyrite cinders, in addition to Fe ₂ O ₃ , contains oxides of FeO and SiO ₂ , is determined by calculation by the chemical composition of the components and the molecular weights of the oxides so that all components do not remain inert and form during firing between solid solutions or compounds. It was taken into account that the following reactions are possible:
a) at a temperature of more than 700 ^o C there is a destruction of calcium hydrosilicates, which played a role to ensure the desired strength after molding

Silicate systems state diagrams: Reference. Vol. 1. Binary systems / Toropov N. A., Barzakovsky V. P. et al. - Leningrad: Science, Leningrad, Dep., 1970. - S. 151-153 / [9];

The selection of the particle size distribution of the filler was carried out with the condition of obtaining a mixture with a maximum density in order to reduce shrinkage deformation during heat treatment. These properties are possessed by a mixture of the following fractions, wt.%: Fr. 1.25 ... 2.5 - 62.5: fr. 0.63 ... 1.25 - 12.5; fr. <0.63 - 25.

 The optimal ratio between binder and aggregate was selected to ensure sufficient mounting and working strength.

For the experiments were used:
spent catalyst for sulfur production at the Sterlitamak gas processing complex;
Tripoli Gorodetsky field;
calcium lime with an activity of 84%;
pyrite cinder of the Chapaevsky chemical plant;
as a filler - crushed and fractionated chamotte grade SHA.

 The chemical compositions of the components are given in table. 1.

 The proposed composition of ceramic concrete is illustrated by the examples given in table. 2.

In the manufacture of products made of ceramic concrete, the batch-weighted components of the binder were subjected to dry joint grinding in a ball mill to a specific surface of 1500 - 2500 cm ² / g. The resulting powder was closed with water in a ratio of 1: 1.1 and subjected to intensive hydration of the suspension with a high-speed mixer for 30-40 minutes. After that, an aggregate of optimal grain size was introduced into the hydrated mass of the binder. The resulting mixture was dried to a molding moisture content of 10-15%. The products were pressed at a pressure of 60 MPa in metal molds with double-sided pressing, then dried at a temperature of 120 ^o C until complete moisture loss. The resulting products were fired in the structure according to the accelerated mode: raising the temperature to a maximum at a speed of 300 ^o C / h, holding at a maximum temperature of 1300 and 1400 ^o C - 3 hours, cooling - 7 hours. The test results of the samples after firing are presented in table. 3.

 From the data presented in table. 2 and 3 it follows that compositions 1-3 are optimal in strength after molding and firing, as well as in thermal resistance. When going beyond the boundary, the purpose of the invention is not achieved. Compositions N 4 - 7 have lower values of thermal resistance, determined by the number of heat exchanges in two modes. For composition No. 4, where tripoli and lime content is above the upper limit, maximum strength after molding is characteristic, but the processes of subsequent intensive destruction of calcium hydrosilicates lead to a significant decrease in strength after firing. With a decrease in tripoli and lime, the products after molding are of low strength (composition N 5), which is explained by the insufficient content of calcium hydrosilicates.

 The introduction of pyrite cinder above the upper limit, as in the composition of N 6 does not lead to increased strength. With a lack of pyrite cinder (composition N 7), the processes of solid-phase reactions do not go through to the end, which affects the strength. The increase in the content of the spent catalyst is not rational, since it is the most valuable component, and, in addition, the excess of its share does not lead to a significant change in properties (composition N 7). When the content of the spent catalyst is less than the lower limit (compositions N 4 and 6), alumina is not enough for solid-phase reactions and the strength after firing is reduced.

 With a total amount of binders (spent catalyst, pyrite cinder, lime and tripoli) of more than 42.5% (compositions Nos. 4 and 5), the largest value of linear changes (shrinkage) after heat treatment was recorded.

 The highest strength of compositions with a content of chamotte aggregate 57.5-62.5%. With an increase in the amount of aggregate (compositions N 6 and 7), the strength decreases both before firing and after it. However, the introduction of more aggregate reduces shrinkage of products. At the same time, the strength of samples with 57.5-62.5% aggregate, both before and after firing, is sufficient for the installation and operation of any design of the thermal unit.

 The compressive strength of the samples after heat treatment is 4.7-5 times higher than the strength of the samples after drying. These data confirm the occurrence of solid-phase reactions between the active alumina of the spent catalyst and iron oxide, as well as between the degradation products.

 The tendency to change the strength according to the prototype is different, since during heat treatment, a decrease in strength is first observed, and then a slight increase (Table 3). The low strength of the products after firing according to the prototype is explained by the presence in the composition of inactive, inert to the interaction of the components. Hardening occurs only due to liquid sintering (gluing) of ready-made refractory phases such as periclase and magnesia spinel, which is ensured by the formation of a melt.

Comparative analysis with the prototype allows us to conclude that the claimed composition is different from the known. Due to the differences in the proposed composition, a new positive effect is achieved, expressed in increasing the residual strength of non-calcined refractory after firing (at operating temperatures) and increasing thermal stability, as well as in protecting the environment by utilizing two wastes: a spent catalyst for sulfur production and pyrite cinder. In addition, the proposed composition of non-fired refractory in comparison with the prototype has other advantages:
technological - as the specific pressing pressure decreases from 120 to 60 MPa;
economic - the cost is reduced by replacing specially burned clinker components with industrial waste;
environmental - the environmental problem is being solved, since two types of large-tonnage waste are disposed of.

 Thus, the search conducted by the applicant for scientific, technical and patent sources of information of analogues and a prototype selected from the list of analogues made it possible to identify distinctive features in the claimed technical solution, therefore, the claimed composition of non-fired refractory meets the criteria of the invention of "novelty".

 The information found does not contain information about the indicated technical result, it does not reveal the influence of distinguishing features on the achievement of the technical result, therefore, this technical solution meets the criterion of "inventive step". The criterion of the invention "industrial applicability" is confirmed by the fact that the use of the proposed composition will allow to find widespread use of waste tonnage, the introduction of the proposed technical solution will not require significant capital costs.

Sources of information
1. Ilyina N.V. et al. Lining of rotary kilns of the cement industry. - M .: Stroyizdat, 1967 .-- S. 46.

 2. A. p. USSR N 1077860, M.C. From 04 to 35/66, 28/06. Raw mix for the manufacture of refractory concrete / Shpolyansky M.A., Wack E.G. and others. - Publ. 06/30/87. - Bull. N 24, 1987 // Discoveries. Inventions

 Z. Arbuzova T.E., Sukhov V.Yu., Ryabova M.V. Technology of composite pressed materials for general construction and special purposes. - Building materials, N 8, 1998. - S. 10-12.

 4. A.S. USSR N 1502534, M.C. From 04 to 33/22. Refractory mass / Suvorov S.A., Makarov V.N. and others. - Publ. 08/23/89. - Bull. N 31, 1989 // Discoveries. Inventions

 5. RF patent N 2016875, M.C. From 04 to 35/00. Non-fired refractory / Perepelitsin V.A., Sprygin A.I. and others. - Publ. 07/30/94. - Bull. N 14, 1994 // Discoveries. Inventions

 6. Menkovsky M.A., Yavorsky V.G. Sulfur technology. - M .: Chemistry, 1985 .-- 328 p.

 7. State diagrams of silicate systems: a Handbook. Vol. 2. Metal-oxygen compounds of silicate systems / Toropov NA, Barzakovsky VP et al. - Leningrad: Science, Leningrad. Dep., 1970 .-- S. 18-34.

 8. Kukolev G.V., Leve E.N. The influence of the production method and the degree of dispersion of alumina on its sintering ability in the presence of various additives. - Journal of practical chemistry. T. XXVIII, N 9, 1955 .-- S. 909-915.

 9. State diagrams of silicate systems: a Handbook. Vol. 1. Binary systems / Toropov N.A., Barzakovsky V.P. et al. - Leningrad: Science, Leningrad, Dep., 1970. - S. 257-260, 151-153.

Claims (1)

An unburned refractory, including hydration components and components that form the ceramic structure, as well as aggregate, characterized in that it contains lime and tripoli as hydration components, and spent catalyst for sulfur production and pyrite cinders as components forming the ceramic structure, and as a filler - chamotte fractional composition, wt.%: fractions 0 - 63 mm - 25; fractions of 0.63 - 1.25 mm - 12.5; fractions 1.25 - 2.5 mm - 62.5 in the following ratio of components, wt.%:
Spent sulfur production catalyst - 20.0 - 22.1
Pyrite cinders - 5.3 - 6.8
Tripoli - 5.6 - 7.2
Lime - 6.0 - 6.68
Fireclay - 57.5 - 62.5n

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