PL152383B1 - MIXTURE FOR THE PRODUCTION OF CERAMIC FURNED MATERIALS - Google Patents

Description

REPUBLIC POLAND PATENT DESCRIPTION 152 383 Additional patent to patent no. --- Int. Cl. ⁵ C04B 33/13 IN Reported: B6 09 12 / P. 261392, / Precedence —-— READER OFFICE 0 1 f L M A PATENT Application announced: 88 06 09 RP Patent description published: 1991 05 31

Creators of the invention: Piotr Wasilewski, Jerzy Czerniec, Andrzej Mianowski, Henryk Stanek, Jan Cebula, Jan Płatek, Tomasz Radko, Jarosław Polański

Authorized by the patent: * Wincenty Pstrowski Silesian University of Technology, Gliwice / Poland /; Polish-German ITHK Company, Chorzów / Poland /

MIXTURE FOR THE PRODUCER OF CERAMIC FURNED MATERIALS

The present invention relates to a composition for the production of ceramic fired materials, in particular bricks.

In the process of etching metal products with a sulfuric acid solution, they brush away the spent etching baths, which are neutralized with milk of lime or hydrated lime.

The purpose of this treatment is to neutralize the residual sulfuric acid and to precipitate hydroxides, mainly iron, so that after filtering off the excess sludge, the filtrate can be reused or discharged to the collector.

In general, humid, water-based sludges, containing 50-70% of water, involve a number of technological measures to restore their functional properties. Due to the serious difficulties in draining these shashams, dehydration is most often used in thermal processes until they become dry.In this case, thermal treatment is not only extremely energy-consuming and expensive, but most of all it leads to significant emissions of oxygen sulfur compounds formed during thermal dissociation of sulfates present in the slime. Such systems are sensitive to the dissociation temperature, and this parameter largely determines their color and the degree of durability. White sludges are used as pigments, inter alia, in many ceramics. There are also known sophisticated technologies for the recovery of magnetite and other oxides or free non-ferrous metals. In general, however, 95-99.5% of sludge is discharged to landfills *.

From the Polish patent description No. 118902, there is known a method of producing ceramic products with the addition of waste sludge from the chemigraphic process. This method seems to be burdened with many shortcomings of a technological nature. First of all, the amount and amount of iron and calcium oxides contained in the said sludge necessitates the use of drying agents in the process of techiologization. Thus, up to 15% by weight of drying material - brick flour, or up to 0.5% by weight of hydrated lime is added, which in practice is reluctant to use due to dusting, hygroscopy and special health and safety requirements.

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Obtaining the content of chloride ions in accordance with the applicant's description at the level of -0.4 wt% in the chemigraphic sludge also requires many technological steps. The proportion of chloride ions in the order of 1% by weight practically eliminates the technological usefulness of the sludge for thermal processes, inter alia, due to the emission of hydrogen chloride. The lack of reactive combinations of gel and calcium present in the chemigraphic sludge means that in order to obtain the expected increase in mechanical strength of products, their total content above 70% by weight is necessary. Consequently, an excess of calcium compounds can result in w; the occurrence of the so-called efflorescence in the final products, while too much iron may increase the thermal conductivity of these products. Thus, the brick mix according to patent description No. 118902 must be composed of three components, i.e. clay, properly prepared chemigraphic sludge and a drying agent.

The above disadvantages are eliminated by the mixture according to the invention. The mixture for the production of ceramic fired materials, in particular bricks according to the invention, containing 75-95% by volume of ideological brick clay, is characterized by the fact that it contains 25-5% by volume of ideological sludge after neutralizing the salvage of metals composed of colloidal iron / 11 / and iron hydroxide systems. (111) in an amount of at least 5% by weight, based on iron. Such a mixture, thanks to plasticization with reactive colloidal hydroxide systems, may contain echo-stimulating components with a low thermal conductivity of 0.1-0.4 W / mK determined at the ambient temperature, in the amount of 5-10% dbt in relation to the mixture. It is preferable to use post-seasoning post-neutralization sludge - to partially dewater it below 40-50% by weight of water without pre-treatment.

In general, the addition of any substances with a high content of iron (11) and iron (111) oxides and calcium to brick clays has a positive effect on the properties of the fired materials, which results from the simple effect of lowering the sintering temperature. This effect was found in the cited patent description No. 118902.

Introducing the sludge according to the invention into brick clayey clay with a clearly reduced proportion of iron compounds, but not less than 5% by weight in terms of iron, unexpectedly increases the degree of homogeunization of the brick mix and unforced self-regulation of the water level in the mix without using it. drying agents. The supposed calculation of this phenomenon consists in the unexpected. properties of wet colloidal iron hydroxide systems / 11 / and iron / 111 /, the spray of the formation of non-techgometrics! 'Cznyoh due to oxygen. On the other hand, the equilibrium states, due to the proportion of water in the preparation phase of the brick mix and later in the accelerated sintering process, use the high elekbokineic potential of the mixed hydroxide systems of iron / 11 / and iron / 111 /, despite the fact that the mass fraction of iron connections in the sludge calculated on iron is on average in the order of 15% by weight, so its share in the brick mix is small.

The neutralization of used digestive baths is aimed at successive neutralization of sulfuric acid residues and precipitation of methyl hydroxides. In this process, the iron / 11 / oxidizes to form iron hydroxide / 111 /, which during the seasoning of the sludge, and then during drying and thermal treatment of the products, finally turns into iron oxide / 111 /. An intermediate step in this process is the reversible reaction of iron hydroxide formation. Its direction depends on the total amount of water in the system. This property enables the stabilization of the moisture of the brick mixture without the need to add drying agents. The brick mix according to the invention creates very favorable conditions for homogenization through plasticization and self-regulation of the moisture level. Dooatkgwo, the beneficial effect achieved after the introduction of the described colloidal systems contained in the sludge into the brick mix is the inhibition of the formation of the so-called calcium efflorescence. Too many calcium canons in the brick raw material is undesirable due to the formation of crystalline overgrowths - blooms in the finished products. When introduced into the raw material together with calcium ions, the stoichometrically equivalent or slightly larger amount of iron ions do not form.

This advantageous effect can be explained by the formation of complex CaO-Fe20p ringlets

152 393 which may contain elements of the calcium-iron spinel structure. Such a structure also has a positive effect on the course of the process in the production of products.

An advantage of the composition according to the invention is therefore that it is easy to dispose of the waste sludge after etching in the direction of the ceramic fired material. It ignores the costly technology of roasting the humid hydroxide noise to the background of the circuits. The physical and chemical properties of the colloidal hydroxide systems contained in the sludge enable better preparation of raw materials for the production of bricks by increasing the h-masenniation and self-regulation of the moisture of the brick mix.

Examples of the use of the invention. In all the examples of using the exchange, the basic raw material for the production of bricks was brick clay - Miocene clay with a grain composition similar to that shown in Table 1 and with a chemical composition presented in Table 2. Table 3 shows the chemical composition of the post-neutralization glass used in the examples of use. as a result of neutralizing the spent etching bites with lime milk, after drying to constant mash at the temperature of 378 K.

Table 1

Grain size, mm Percentage of £ Age 4+ 0.0 2-4 1.88. 1 - 2 2.62 0.5 - 1 . 3.40 0.2 - 0.5 2.10 0.06 - 0.2 5.18 Less than 0.06 84.82 Blackboard 2 Chemical composition 1 It changed in% by mass Ignition losses 11.14 SiO2 56.50 ^a1 2 ° 3 14.10 ^P * 2 ° ³ 5.50 CaO 4.90 MgO 3.05 K20 2.30 On ₂ O 0.39 TiO2 0.79 SO ^ 1.48

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Table 3

- Ingredient Percentage by weight, 4 Sample 1 Sample 2 Sample 3 Medium r ~ soy- 32-35 30-32 30-32 30.7-33.0 P ^{e3 +} / Fe ²⁺ 15.8-17.3 15.8-17.3 8.6-10.1 13.5-14.9 Ce ²⁺ 18.7-22.6 18.0-20.2 20.2-23.0 18.9-21.6 ^ul 2 ° 3 3.0-4.0 3.0-4.0 3.0-4.0 3.0-4.0 MgO 0.4-0.6 0.4-0.6 0.4-0.6 0.4-0.6 other 3, O-5, O 7.0-13.0 7.0-17.0 5.7-11.7

Example I · * on a laboratory scale, a mixture for the production of bricks was prepared, containing 804 by volume of brick clay and 204 by volume of post-neutralization sludge with a water content of 454 by weight. After obtaining the appropriate plasticity and homogeneity, the bricks with 35x25x15 mm calibrations were obtained. The bricks were air dried at room temperature in 1 laboratory dryer at 363 »and then they were poured in a muffle furnace at 1223 K ·

The following parameters were determined for the bricks obtained:

- ^Ge s ^t OSS actual p _r "228 ° kg / m ^

- ^{t g} es oad ozorną ^p-p = ΊόβΟ kg ^ rn ^

- porosity P = 274

- tenderness N = 184

The fragment of the bricks was well sintered, uniform in the turn ·

Example 11 · A mixture for the production of bricks was prepared on a laboratory scale, containing: 754 by volume of brick clay, 154 by volume of post-neutralization sludge with the content of 454 by weight of water and 104 by volume of technical microspheres with a thermal conductivity coefficient of Λ = 0.246 W / mK determined at room temperature The donation of bricks and the method of production are given in example I

The following parameters were determined for the bricks obtained:

- actual density ²⁰⁸⁰ kg / m2

- ^Ge hundred ozorn ^{SC p and} p _p = ¹ 3 ^{60 kg} ^ m ^

- porosity P = 35 &

- / ascension N = 224

Example d III. On an industrial scale, a batch of perforated bricks was produced from a mixture of: 604 volumetric clay bricks, 204 volumetric post-neutralizing sludge with a content of 604 by weight water. with technological instructions ran smoothly. Table 4 presents the parameters of bricks from the current production and brick-works and made of a mixture with the addition of e-neutralization sludge according to the index

Table 4

Paramer ¹ - Ί Current production Production according to the invention Compressive strength / MPa / 3.0 3.5 Nasiąk ^^ ć / 4 / 15.4 16.4 Volumetric weight / kg / m ^ / 1150 1100

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Claims (3)

Patent claims 1 · Mixture for the production of ceramic fired materials, especially bricks, containing 75-955% by volume of brick clay j, characterized by the fact that it contains 25-5% by volume of post-neutralization sludge - from etching of metals composed of colloidal iron hydroxide systems / 11 / and iron / 111 / in an amount of at least 5% by weight, based on iron. 2. Mix according to claim 1, characterized in that it contains slimming components in an amount of at least 5-1% by volume with a thermal conductivity of 0.1-0.4 W / mK determined at ambient temperature. Mixture according to claim 1 or 2, characterized in that the post-neutralization sludge is partially dehydrated to a level of more than 40-50% by weight of water without pre-treatment.