BG64820B1 - Process for turning out civil engineering articles and ceramic mass for the production thereof - Google Patents

Abstract

Bricks, ceramic blocks, tiles and large size blocks are produced by the method. The ceramic material is prepared by mixing clay, sand as filler, calcium oxide and aqueous solution of a hardener and sodium silicate as liquid glass. The products are moulded and subjected to heat treatment including a stage of preliminary drying, heating in humid medium in a closed space saturated by steam and subsequent drying by continuous reduction of humidity. The pre-drying is made in humidity levels of 10-12% at temperature range from 50 to 60 deg. C in a humid atmosphere û at temperature range from 95 to 105 deg. C for 2 hrs, subsequent drying for 8-10 h at temperature range of 120 to 130 deg. C to a level of residual humidity of 10 to 15%. The dry components content in the ceramic material is calculated as dry matter and includes, in mass %: filler û sand, from 0.1 to 50.0, calcium oxide from 3.4 to 15.0, hardener 0.1-4.0. sodium silicate 0.1-4.0, the remainder being clay.

Description

(54) METHOD OF MANUFACTURING CONSTRUCTION PRODUCTS AND CERAMIC MASS FOR PRODUCING THEM

Technical field

The invention relates to a method of manufacturing construction products and ceramic mass for their production, which are used in the manufacture of bricks, ceramic stones, tiles, blocks of large sizes.

BACKGROUND OF THE INVENTION

A method for the production of building materials is known, including the preparation of a molding compound composed of clay, sand filler 0.1-50.0%, calcium hydroxide 4.5-20.0% in the form of slaked lime mixed with aqueous solution of hardener 0.3-4.0%. The molding of the articles and their processing involves the step of pre-drying, heating in a humid environment in an enclosed space saturated with money, and subsequent drying with a gradual decrease in humidity. Pre-drying is carried out to a humidity level of 12-14% at a temperature of 60-70 ° C, and heating in a humid environment is carried out at a subsequent drying for 8-10 h, with a gradual increase in temperature to 120 ° C and retention at this temperature / 1 /.

The method cited has the following disadvantages:

The use of calcium hydroxide / slaked lime / increases the cost of production, requiring its use in the form of pieces that are partially carbonized in the process of preparing the mass, pre-drying and heating in a humid environment, which reduces the water resistance of the products.

During the preparation of the molding mass, there is insufficient dissolution of the clay, which negatively affects the water absorption, water resistance and resistance to low temperatures of the products, as well as the stability of the properties of the finished products during the different seasons of the year.

The products have a high water absorption capacity, which makes it difficult to use them to cover buildings and to cover roofs with tiles.

SUMMARY OF THE INVENTION

The method of manufacturing construction products according to the invention involves the preparation of a ceramic mass consisting of clay, sand filler, calcium oxide mixed with aqueous hardener solution and sodium silicate, which consists in pre-mixing the components by embedding the hardener in clay, mechanical mixing of the prepared mass with quicklime, dissolution of the clay for 12-14 h and final mixing of the molding mass.

The molding of the articles and their processing includes the steps of pre-drying, heating in a humid environment in a vapor-saturated enclosure, and subsequent drying with a gradual decrease in humidity, with the pre-drying having a humidity level of 10-12% at 50- 60 ° C, heating in a humid environment is carried out at a temperature of 95-105 ° C for 2 h, and subsequent drying is carried out for 8-10 h with a gradual rise in temperature to 120-130 ° C to a residual level humidity of the order of 1, 0-1,5%.

The crude ceramic mass for the production of building materials according to the invention according to the proposed method has the following composition in wt.% Calculated as dry matter:

-filler-sand 0,1-50,0

- calcium oxide / quicklime / 3,4-15,0

- hardener / caustic soda, soda ash, ammonium salts / or mixtures thereof 0,1-4,0

- sodium silicate 0.1 -4.0

- the rest is clay.

An example of an embodiment of the invention

The clay from the quarry enters the loosening facility and moves through the belt conveyor to the feeder. The sand from the quarry does the same with a conveyor belt and goes into the same feeder. The sand is metered there in terms of the amount of clay. From the storage site, the clay-sand mixture is conveyed by conveyor to the sand-clay mixture hopper located above the plate feeder. The dispenser delivers the required amount of mixture on the conveyor to the mixer.

Hardener / e.g. an aqueous solution of sodium hydroxide or calcined soda or ammonium salts / with the sodium silicate dissolved therein (eg water glass) is fed into the front of the mixer with a dispenser of liquids.

Calcium oxide is fed in the required quantity, by pneumatic transport from the storage part into the hopper and from it into the middle part of the mixer with a screw feeder-dispenser. Water is introduced into the mixer as needed to process the clay and lime wetting mass.

The ceramic mass prepared in the mixer is fed with a belt conveyor, a squeegee, a rolling mill, grinded in bulk and stored in a charge storage room, where it remains for 12-24 hours.

From the charge store with a multi-bucket excavator, the mass is fed along a conveyor belt to a screw mill. It is finely ground and fed to a vacuum press. Planetary, rotor or other mills may be used in place of rollers and auger mills to ensure the dispersion and even distribution of components in the mass.

The molding humidity of the resulting mass is 16-24% depending on the plastic and rheological properties of the clay.

The block formed in the vacuum compressor is cut with a machine for cutting the products of the required length, and the received products are loaded on special pallets in cassettes. Crane carts are loaded into the humidifier with periodic action. The load factor of the camera according to the volume of the working area is 0.5-0.75.

In the chambers, a forced circulation of an energy carrier (steam-air mixture) is carried out in a closed loop: heat exchanger working zone-heat exchanger.

Under a special program, the product is heated uniformly for 0.5-1 hours to a temperature of 60 ° C outdoors and kept at this temperature until it reaches a humidity of 10-12%. It is then heated indoors to a temperature of 95-105 ° C, with the heating rate not exceeding 60 ° C / h and remaining at this temperature for 2 hours. The temperature was then raised to 120-130 ° C for 810 h. Excess moisture (no more than 10% / h) is removed from the camera.

Subsequently, the final removal of moisture from the chamber is carried out for 2-3 h by gently replacing the vapor-air medium with the dry air chamber, maintaining a temperature of 120130 ° C in the chamber. When the humidity in the chamber is reduced to 1-1.5%, the heat supply to the chamber is stopped and cooling to a temperature of 70 ° C is started, by supplying atmospheric air, the speed of cooling of the product must not exceed 50 ° C. / h. After the product has cooled to the specified temperature, the chamber is opened, the product cartridges are unloaded with an electric crane at the finished production site, where the products are removed from the cassettes and sent to the finished production warehouse.

The table gives examples of specific components of the raw ceramic mass for clay with different mineralogical composition, the estimates refer to the weight of the components in the dry state and the properties of the products prepared by them using the method. Calcium hydroxide is introduced in the form of quicklime and the hardener is sodium hydroxide. Sodium silicate is introduced in the form of a liquid glass module 1.6.

The optimal composition of the different clays corresponds to high strength, high coefficient of water resistance, low degree of water absorption, increased resistance to low temperatures of the produced material, good plasticity of the molding mass, especially necessary for forming large-sized products.

Mixtures containing the upper limit of calcium hydroxide and hardener have a higher compressive strength but have a low water resistance, due to the high content of these components.

Mixtures containing the upper bound of sand and low clay content are characterized by a decrease in the plasticity of the mat and the strength of the material. The low content of sand causes a decrease in strength, with the heat treatment increasing the amount of cracks in the articles and, accordingly, the percentage of marriage increases due to the high coefficient of density of the body during drying.

The maximum content of calcium hydroxide (20%) is determined by economic considerations (relatively high cost), as well as by the lack of a significant influence on the properties of the finished product as its content is further increased.

The minimum content of calcium hydroxide and hardener is determined by the reduction of the strength characteristics and the water resistance of the finished products.

The maximum content of the hardener is determined by the appearance of salts on the surface of the articles, ceasing to further improve the properties of the finished products, as well as by economic considerations.

The replacement of the sodium base as a hardener with calcined salts, ammonium salts or a mixture of these substances is carried out by recalculating the sodium hydroxide or hydroxyl ions and does not significantly alter the results obtained; however, the formation of ammonium salts reduces the formation of salts maximum content of hardener.

The minimum sodium silicate content is determined by the amount of low modulus silicates in the clay composition, and the maximum sodium silicate content is determined by the amount of high modulus silicates in the clay composition.

Simultaneously with the introduction of the sodium silicate, the curing activator is proportionally introduced with mixing.

TABLE

- -------——— -. it: ———: -: ----- - .. - ¹ ------------ Content of components in wt% dry matter Properties of finished articles ---- 1 Source clay 0 CO - CL «X ° ° - Do I ® b b f M f F (0 ® ® F * ho X H XX I £” * ^yao - ³ * £ Ξ ί 'x o h h h and b h n H «<O® ® * i ^x * ® and <c x x ο ® о · < ⁼ oh x 1 Ο е »о а х а а х ί» о а х ч б х х а е т- о ω -и х ο о (- XX · Б С о <_ S О © · О О ЯН с “® ^a ® ^and k = 1. O O O o o _w ® X AND COW X w Remarks № 1 53.50 32.00 11.00 3.50 320 0.85 12 70 Prototype 56.39 33.54 - 6.40 - 3.67 55.18 32.89 - 8.34 - 3.59 54.14 32.52 - 10.00 - 3.54 55.13 32.85 - 8.33 0.10 3.59 55.08 32.82 - 8.32 0.20 3.58 54.90 32.73 - 8.30 0.50 3.57 280 0.81 350 0.87 10 76 310 0.84 360 0.87 380 0.92 5.6 88 320 0.85 Optimal Optimal № 2 80.00 10.00 8.80 1.20 270 0.83 13 70 Prototype 84.56 10.57 - 3.40 - 1.27 81.89 10.22 - 6.66 - 1.23 80.00 10.08 - 8.00 - 1.20 81.06 10.12 - 6 , 59 1.50 0.73 80.94 10.11 - 6.59 1.70 0.66 80.55 10.00 - 6.55 2.50 0.40 210 0.77 300 0.85 11 75 280, 81 310 0.85 340 0.88 9 80 290 0.79 Optimal Optimal № 3 65.50 16.40 17.45 0.65 200 0.84 13 70 Prototype 70.60 17.70 - 10.00 - 0.70 68.98 17.12 - 13.22 - 0.68 67.59 16.81 - 15.00 - 0.66 68.80 17.07 - 13.18 0.40 0.55 68.59 17.01 - 13.14 0.90 0.38 68.30 16.93 - 13.09 1.50 0.18 210 0.79 240 0.86 12 72 220 0.82 270 0.79 310 0.88 10 76 290 0.76 Optimal Optimal № 4 66.00 16.80 15.70 1.50 320 0.85 12 70 Prototype 71.07 17.93 - 9.40 - 1.60 68.65 17.90 - 11.89 - 1.56 68.19 17.27 - 13.00 - 1.54 67.75 17.63 - 11 , 73 2.00 0.89 67.32 17.46 - 11.66 3.00 0.56 66.86 17.93 - 11.58 4.00 0.23 240 0.78 350 0.89 9 77 380 0.80 350 0.86 380 0.93 7 85 340 0.78 Optimal Optimal

Claims (4)

1. Method for the production of construction products by the preparation of a molding mass consisting of clay, sand, calcium hydroxyl, mixed with aqueous hardener solution, plastic molding of the articles and their heat treatment, including the stage of pre-drying, heating in humid environment in a vapor-saturated enclosure and | θ subsequent drying with a gradual decrease in humidity, characterized in that the calcium hydroxide is introduced as calcium oxide and the molded ceramic mass is prepared in three stages: but drying Di- | $ stirring for 12-24 h until final quenching and hydrolysis of the clay, and final blending until a homogeneous mixture is achieved, whereby the introduction of the components of the molding mass is carried out, initially to the clay-sand mixture. the hardener is added and then calcium oxide is added. Method according to claim 1, characterized in that the pre-drying was carried out at a humidity level of ΙΟΙ 2% at a temperature of 50-60 ° C, heating in a humid environment was carried out at a temperature of 95-105 ° C during 2-4 h, and subsequent drying is carried out for 8 - 10 h, with a gradual increase in temperature from 100 ° C to 13 ° C to a degree of residual humidity of the order of 1.5-2.0%. 3. Ceramic mass for the manufacture of construction products, including clay, sand, calcium hydroxide in the form of lime and a hardener in the form of sodium hydroxide, soda ash, ammonium salts, and a mixture thereof, characterized in that instead of calcium the hydroxide contains calcium oxide and additional sodium silicate, for example in the form of liquid glass. Ceramic mass according to claim 3, characterized in that it contains the indicated components in the following ratio by weight, calculated as dry matter: - sand 0,1-50,0 - calcium oxide 3,4-15,0 - hardener 0,1-4,0 - sodium silicate 0.1 -4.0 - clay the rest. Literature 1. BG 61566. Publication of the Patent Office of the Republic of Bulgaria 1113 Sofia, 52-B Dr. GM Dimitrov Blvd.