DE2818169A1 - METHOD FOR MANUFACTURING PLASTER PRODUCTS - Google Patents

Description

I.

Proizvodstvenno-tekhnieheskoe obiedinenie "Rosorgtekhstrom" Rostovsky-na-Donu branch

PROCESS ZTOi MANUFACTURE OF PLASTER PRODUCTS

NISSEH

The present invention relates to building materials, in particular to methods of making plaster products.

The invention is used in the manufacture of cladding panels for exterior and interior finishing
of buildings, of architectural components, finishing elements in the construction industry.

In modern production, building plaster is used as hemihydrate
GaSO · 0.5 HO, which is obtained in special companies, is used as a basic raw material for the manufacture of plaster products. _{Natural gypsum stone (CaSO ^ · 2 H 2} O) is broken in ball mills for the production of the above-mentioned building plaster

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crushed into powder. Thereafter, the crushed gypsum in specific Gypsum boilers is subjected, with stirring and at a temperature of about 180 ⁰ C over a period of 4 to 8 hours to a heat treatment · After cooling gypsum is packaged in a protected against the ingress of moisture condition for the production of gypsum products forwarded to the production companies.

When manufacturing components, building plaster hemihydrate CaSO ^ '0.5 H ₂ O is moistened with water a few minutes before the molds are pulled (the water-plaster weight ratio is 0.4 to 0.6). It takes 5 to 15 minutes for the plaster to harden in the mold. After stripping the product obtained is dried according to the size of the products Dei a temperature of from $ 0 to 6O ⁰ G in the course of 8 to 16 hours.

All products manufactured using the known process have a high porosity and water absorption capacity and can therefore only be used for interior construction work (partition walls, Floor covering, visible surfaces and sound-absorbing panels) can be used. Also is the known method difficult to implement because it requires the use of a raw material that has been pretreated in a certain way.

Also known is a process for the production of plaster products, which allows the breaking of gypsum stone - natural gypsum double hydrate CaSO ^ · 2 H ₂ O up to the formation of partial

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surfaces with a specific surface area of 2500 to

2800 cm / g, and then mixing the broken gypsum stone with water in amounts in which the water to gypsum weight ratio is 0.1 to 0.2. Products are then formed from the prepared mixture by pouring the mixture into the mold. For compaction, the mixture is subjected to shaking. The molded components are subjected to a hydrothermal treatment in a water vapor atmosphere under a pressure of 70 to 7 * 5 atm. The hydrothermal treatment mentioned takes place in a pressure vessel, where building plaster double hydrate is dehydrated to building plaster hemihydrate. To solidify the products through hydration, they are immersed in water until they are saturated. (SU copyright certificate No. 502653)

A disadvantage of this process is the high moisture content of the mixture to be molded, which in connection with the subsequent heat-moisturizing treatment of the products leads to the production of products that have a porous structure - the water absorption capacity is 10 to 20% - and insufficient frost resistance - 10 to 15 cycles - have (one cycle means freezing to a temperature of -15 to -20 ⁰ G over the course of 4 hours and thawing in water over the course of 4 hours). In addition, the implementation of the heat treatment in

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Pressure vessel, which is a periodically acting equipment, no possibility of gypsum products in the flow process and automate the process as a whole.

Is also known a method described in SU-Author's Certificate no. 62733 A method of producing gypsum products. According to this process, the crushed gypsum stone - JNacurgips double hydrate CaSO ^ * 2 H ₂ O - is moistened to 6 to 10% if necessary in the presence of fillers in the case of the manufacture of products by pressing or tamping. In the case of the manufacture of products by pouring or shaking in, the mass is moistened with a larger amount of water until it has a plastic consistency. The components formed in this or that way are subjected to a hydrothermal treatment, for which the products are placed in a pressure vessel to which steam is supplied under a pressure of at least 1 atm. Storage under pressure takes 3 to 6 hours. According to the above-mentioned author's certificate, the building gypsum double hydrate is recrystallized even at low pressures (1 to 1.5 atm) by converting into the building gypsum hemihydrate with the occurrence of Maxt forces between the crystals of the hemihydrate, which gives the products considerable strength immediately gives the hydrothermal treatment. Then the water vapor is slowly released. Huh

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hydrothermal treatment and cooling takes place in the products the hydration process of gypsum hemihydrate dissolves the water remaining in the forums, which is accompanied by an additional increase in strength

The disadvantages of the process mentioned are inherent in

highlighted the previously mentioned procedure · Bs must it should be noted that using the mentioned Process of molded products from the mixtures of plastic consistency (the water / plaster weight ratio is more than 0.1) practically cannot have high values of resistance to frost and water. In hydrothermal steam treatment In the pressure vessel, the porosity of the products formed by pressing is less than 14 to 15% and the required values of frost resistance (35 Cycles and more) not achieved.

ms is the purpose of the present invention to eliminate the disadvantages mentioned.

The invention is based on the object of a method for producing such low-pore plaster products to create that have increased water and frost resistance.

This object is achieved in that in the production of plaster products by a method that is described in the shape of the crushed natural gypsum double hydrate

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CaüO · 2 H "0 with subsequent heat treatment and solidification of the molded products, according to the invention the mentioned heat treatment of the molded products is carried out in the air atmosphere at a temperature which is ^{equal to a value within 100 to 200 0} C, the temperature rise up to the mentioned value proceeds at a rate of 2 to 3 degrees / min, after which the heat-treated products are cooled to a temperature not exceeding 50 ° G, and the products are solidified by moistening them.

The method according to the invention offered the possibility of producing plaster products with the following properties which are unusual for plaster products: water absorption 7 to 15%, frost resistance 40 to 30 cycles, compressive strength of the products 170 to 300 kp / cm.

To ν monolithic structure and a sufficient To ensure high strength of the gypsum products during their solidification, the heat treatment is used in the course of a Time taken for the dehydration of at least 90 to 95 vol.% Building plaster double hydrate of the formed Components is necessary.

To achieve a value for the water absorption of Fercigips products within 7 to 10%, according to the invention, a comminuted, water-mixed construction gypsum Dop-

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formed pelhydrate, with the water-eye gypsum double hydrate -Weight ratio is 0.04 to 0.15 and more suitably 0.05 to 0.10.

ü for the manufacture of plaster products, the products Replace marble, granite and other types of stone, it is expedient according to the invention to use the ßaugips double hydrate comminuted to a fraction with a particle size of 1 to 10 mm in an amount of 40% by weight and up to one Fraction with a specific surface area of the particles of

2
To form 1700 to 1800 cm / g in an amount of 60% by weight,

for the production of Üir certificates with a denser Structure and better mechanical properties and rust resistance, it is expedient, according to the invention, to shape the syrup products by pressing at a specific

2
To carry out a pressure of at least 60 kp / cm

The aforementioned and other objects and portions of the present invention will be made apparent from those set forth below detailed description of the method of manufacture

the
of plaster products and / or implementation examples of the same

explained in more detail.

In the implementation of the method proposed in the present invention, the natural gypsum stone, ie the building gypsum double hydrate CaSO ^ 2 RpO, is used in a preparatory step in a jaw and hammer crusher up to a specific surface area of the particles of 100 to 200 cm ² / g.

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is broken, as the starting material. The actual size of the specific surface area of the starting material depends on the thickness of the product that is intended to be manufactured. So is; it is, for example, expedient to break the gypsum stone up to a specific surface area of 600 to 900 cm / g with a thickness of the future product of 15 to 30 mm. With the üickenverminderung the specific surface area of the broken stone to increase, Jei the preparation of (iipserzeugnisse ¹ ^ ax Articles made of marble, granite and other Mausteinaruen replace, we also propose a mixture of calcined gypsum-Doppelnydrat that up to a fraction of 1 to 10 mm and a fraction with a specific surface area of the particles of about 2000 cm / g was used as starting material . % Fraction with a specific surface area of the particles of 1700

2
to mix up to 1d00 cm / g.

The building gypsum double hydrate CaSO ^ * 2 H ₂ O, which is fine to the required size, is moistened with stirring until a mixture is formed in which the weight ratio of water / gypsum double hydrate is 0.04 to 0.15. The size of the said ratio depends on the conditions of the subsequent shaping and the characteristics of the equipment used; so the water-building plaster double hydrate weight ratio must be used when molding the product

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se aui two-stage presses with a specific pressure of

75 to 250 kgf / cm are 0.05 to 0.07. Besides, it must water-building plaster double hydrate weight ratio, as said above, for the production of plaster products, the water absorption of which is 7 to 15%, 0.05 to 0.1.

Products are formed from the prepared mixture, e.g. by pressing or vibrating Pressed products do not have to have the specific pressure

be below 60 kp / cm. ISs were determined experimentally by us, that if this condition is observed, products with a denser structure and "better mechanical properties." getting produced.

The molded plaster products are fed to a system for their heat treatment, for example a continuous dryer or a tunnel dryer. According to the present invention, the thermal treatment of the molded products is carried out in the air atmosphere. The temperature rise in the i'rockner (, from room temperature) proceeds at a rate 2-3 deg / min up to a chosen in the range between 100 and 200 ⁰ C vVert on. The maximum temperature at which the heat treatment takes place and the duration of the heat treatment depend on the thickness of the product. Pure 6 to 7 mm thick products, the maximum temperature value is, for example, 150 to 160 ⁰ G, whereby the J & r certificate is stored at the stated temperature for a time that

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for the dehydration of at least 90 to 95% by volume of gypsum double hydrate of the molded products is necessary and sufficient. In the case of the dehydration mentioned, the Keeping the process practically complete, and further storage of the products in the dryer is economical inexpedient. During the heat treatment of the products, the natural gypsum double hydrate CaS (X · 2 HpO with the excretion of mechanically bound as well as crystallized water in the plaster of paris hemihydrate CaSO. · 0.5 HpO over, being the starting crystal structure because of the recrystallization of double hydrate to hemihydrate is disturbed. With a certain degree of compaction the mixture takes place when molding during heat treatment a certain destruction of building plaster double hydrate particles takes place, to which a constant release of water contributes. It will

the

the contact area ^v individual particles larger. The subsequent solidification of the products, which takes place during moistening, already takes place in a changed coarse structure of the product - the crystallization of building plaster double hydrate will promote an increase in strength and a greater decrease in porosity of the product. It must be pointed out that it is inappropriate to raise the temperature of the heat treatment above 200 ° C, because the formation of anhydride at temperatures above 200 ⁰ C is possible, to reduce the strength and

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Prost resistance values of the products leads.

After heat treatment, the product can be applied to any known way e.g. by air cooling by means of a fan

convection
or more natural ^v cooled to 40 to 50 0. The product is then moistened to saturation, i.e. wetted with an amount of water that is necessary for the crystallization of building plaster hemihydrate to form building plaster double hydrate. Based on the weight of the dried product, this amount is approx. 1 <3% by weight. The moistening can be achieved by immersing the product in water,

or
dustier ^ by saturating the product with water vapor

be brought about.

As a result of the water saturation, the building plaster hemihydrate OaSO ^ * 0.5 H ₂ O goes back into the building plaster double hydrate GaSO. · 2 H ₂ O, whereby it recrystallizes to form a solid structure.

The products are then dried naturally or inevitably, which gives them an ultimate compressive strength of 100 to 300 kp / cm ² .

If necessary, the finished product can be ground, polished or any other surface treatment according to known methods.

The present invention envisions the possibility of adding a color such as a mineral color into the initial mixture of georoched building plaster double hydrate

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CaSO ^ · 2 H ₅ O with water, which brings a change in the color range of the finished products and does not affect their manufacturing process.

The structural analysis of the plaster product can be used to determine the process by which it was manufactured is.

As can be seen from the wording of the description, the method according to the invention enables production an extensive nomenclature of Gipssteinerugnxsse with increased physical-mechanical properties and extended area of application in sow beings.

Because the frost resistance of these products the frost resistance of the known plaster products exceeds 6 times, they can be used for exterior cladding of buildings and structures are used. The shaping by pressing also offers the possibility of Manufacture products of different designs and obtain a visible surface with an ornament.

The technology of the invention also provides a waste-free operation and does not pollute the environment.

Example 1.

Natural gypsum stone is put in a jaw crusher and after that in a ball mill up to a specific upper

O
area of the particles of 1000 cm / g crushed. The humid

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The powder is moistened to form a mixture with a water / gypsum stone weight ratio of 0.07 and the latter is molded on a hydraulic press at a specific pressure of 150 kp / cm. The molded product is placed in a drying cabinet in which it is subjected to a heat treatment during which the temperature in the cabinet is increased at a rate of 2 ° G / min up to 160 ° C. At this temperature, the product becomes 1.5 hours stored for a long time, after which it is cooled ^{to a temperature of 47 0 G in the course of 20 minutes.} The product is then moistened to saturation by immersing it in a water bath and then dried in the open air.

The compressive strength of the finished product is

115 kp / cm, frost resistance - 50 cycles, water absorbency 9%

Example 2.

Efatur gypsum is crushed in a jaw crusher. After that, part of it is put in a ball mill up

to a specific surface area of 17OO cm / g and the other part crushed in a hammer crusher to a fraction of 1.0 to 10.0 mm.

Then 40 wt.% Of the gypsum fraction is 1.0 to 10.0 mm with 60 wt.% Gypsum powder having a specific

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see surface of 1700 cm / g mixed and the processed mixture up to a water-gypsum stone weight ratio of 0.06. The mixture is on a press

molded at a specific pressure of 170 kgf / cm. The product obtained is placed in a drying oven in which the temperature is increased at a rate of 2 ° C / min to 180 ⁰ G. The product is stored at this temperature for 2 hours and then naturally cooled to a temperature of 43 ° over the course of 30 minutes.

Thereafter, the product is moistened by atomization of moisture on its surfaces and easily dried in a drying oven at a temperature of 5O ⁰ G in the course of 3 hours.

The finished product is marked with a on the front Grinding wheel ground.

The compressive strength of the finished product is 280

kp / cm, frost resistance - 50 cycles, water absorbency 10%.

Example 3 «

Uatur gypsum stone is crushed in a jaw crusher. After that, part of it is put in a ball mill up

to a specific surface of 2000 cm / g and the other part of the gypsum stone in a hammer crusher up to a fraction of 1 to 7 mm.

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Thereupon 40 wt. % Gypsum stone with a fraction 1 to 7 are now. with 60 wt.% ground gypsum with a specific surface of 2000 cm / g is mixed. The prepared mixture is moistened until a water / gypsum stone weight ratio of 0.1 is reached. The mixture is put on a press at a specific pressure of

ρ
200 kp / cm molded. The finished product is placed in a drying oven in which the temperature rise (from room temperature) at a rate of 3 deg / min up to a temperature of 1Ö0 ° G is going · For iiehydratation of 90 vol.% Alabaster-Doppelhydrat of the molded product the product is stored for 1 hour at this temperature then the product is cooled down ^{at room temperature in the course of 30 minutes to a temperature of 40 ° G}

The cooled product is moistened to saturation by atomizing moisture onto its surface and ^{lightly dried in a drying cabinet at a temperature of 50 °} C. over the course of 3 hours.

It is possible to grind the finished product on the front with a grinding wheel

The compressive strength of the finished product is 240 kp / cm, the frost resistance - 45 cycles »

Example 4.

Natural gypsum stone is processed in a jaw crusher and then in a ball mill to a specific surface area of

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100 cm / g comminuted, moistened until a water / gypsum stone weight ratio of 0.05 is reached and molded on presses at a specific pressure of 20 kg / cm ¹ ". The molded product is placed in a drying cabinet, in which the temperature is set a rate of 2 deg / min to a (temperature increased from 140 ^0G. the shelf life for this! temperature is 1.5 hours ^ and during this time the dehydration of 95% by volume · Alabaster-Doppelhydrat takes place.

The product is cooled under natural conditions to a freezing temperature of 50 ° C over the course of 20 minutes. Moistening takes place by atomizing moisture onto the surface of the product. The subsequent drying of the product takes place in the drying cabinet at a temperature i ^? on 50 G over the course of 3 hours.

The compressive strength of the finished product is

kp / cm, the frost resistance - 40 cycles.

Example 5.

Gypsum stone with natural moisture of 5% is made Broken down to a specific Oberflach® of 800 cm / g and fed to the shaping by pressing. The pressing

follows o at a specific pressure of 300 kp / cm · the heating of the molded products up to a temperature of 160 ° G is carried out at a rate of 2 degrees / min. Storage at the maximum temperature of the product

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takes 2 hours, the dehydration of external

gypsum double hydrate is 92% by volume. The product is cooled down ^{to a temperature of 40 °} C. in the course of 30 minutes under natural conditions.

The moistening of the products was

cnen carried out into the water until saturation. The compressive strength of the finished product <frost resistance - 45 cycles.

strength of the finished product is 150 kp / cm, the

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Claims (1)

PAIBBIABSFEÜCHI (I · / ¹ method for the production of plaster products, which comprises the shaping of crushed natural gypsum double hydrate OaSCL 2 H ₂ O with subsequent heat treatment and solidification of the molded product, characterized in that the above-mentioned heat treatment of the molded product in an air atmosphere at a Temperature from 100 to 200 ⁰ O takes place, the temperature rise up to the mentioned value at a rate of 2 to 3 degrees / min, after which the heat-treated products are cooled to a temperature of not more than 50 ° G, and the solidification of the products by their Moistening takes place. 2. Process for producing plaster products according to claim 1, characterized in that the heat treatment is carried out over a period of time which is necessary for the dehydration of at least 90 to 95% by volume of gypsum double hydrate of the molded products. 3 · The method for producing plasterers products according to any one of claims 1 $ _t 2 characterized ge - 8Q98U / Q9SS 281816S kennze rest t ₉ that pulverized, mixed with water Alabaster-Doppelhydrat _s is formed wherein the water-Alabaster-Doppelhydrat-üewichtsverhältnis 0.05 to 0.1 » 4e A method for producing plasterer products according to any one of claims 1 to 3 s characterized in that the eye gypsum hi-hydrate, comminuted up to a fraction of 1 to 10 hue in an amount of 40 % by weight and up to a fraction with a specix'isehen The upper surface area of the particles is from 1700 to 1800 approx / g in an amount of 60% by weight «. 5 »Procedure for the manufacture of plaster products any one of claims 1 to 4, characterized in that, that the! shaping of the products by EE? essea at a specific pressure of at least 60 kp / cffl is carried out »