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INVENTION
Patent of the Russian Federation RU2286965

A METHOD OF OBTAINING A MAGNESIUM BINDING

The name of the inventor: Kramar Lyudmila Yakovlevna (RU); Trofimov Boris Yakovlevich (RU); Chernykh Tamara Nikolaevna (RU); Zahezin Alexander Evgenievich (RU); Gorbanenko Vyacheslav Mikhailovich
The name of the patent holder: Kramar Lyudmila Yakovlevna (RU); Trofimov Boris Yakovlevich (RU); Chernykh Tamara Nikolaevna (RU); Zahezin Alexander Evgenievich (RU); Gorbanenko Vyacheslav Mikhailovich
Address for correspondence: 454016, Chelyabinsk, ul. Tchaikovsky, 185, app. 503, L.Ya. Kramar
Date of commencement of the patent: 2005.05.23

The invention relates to the production of building materials, in particular to a method for producing a magnesia astringent from high magnesian rocks - magnesite or brucite, containing magnesium-serpentinite hydrosilicates, ultrabasites and the like, as well as from a specially formulated magnesite batch with natural magnesium silicosilicates, and can Be used for the production of building board products and panels for the interior cladding of buildings, window sills, staircases, and for the production of dry construction mixtures, heat insulating materials and products for the installation of monolithic floors. The technical result is the preparation of a magnesia binder high in strength, not prone to cracking and having low linear shrinkage during hardening, and the expansion of the raw material base for the production of a magnesia binder. In the method for producing a magnesia binder, high magnesian rocks containing 15-40% by weight of magnesium hydrosilicates are crushed to a fraction of less than 60 mm, baked at 1050-1100 ° C for 2-3 hours, then ground into powder-passed through a 008 sieve - 78-84%.

DESCRIPTION OF THE INVENTION

The invention relates to the production of building materials, in particular to a process for the production of magnesia astringent from waste materials for the production of magnesia refractories including high magnesian rocks (magnesite or brucite) and magnesium hydrosilicates - serpentinites, ultrabasites and the like, and from a specially formulated charge Magnesite with natural magnesium hydrosilicates.

Known raw material for the preparation of binder (RU 937396, C 04 B 9/06, 1982), containing serpentinite and limestone in the following ratio, by weight:

The firing of this mixture is carried out in a rotating cement kiln at 1400 ° C. In the obtained system there is an active dicalcium silicate and magnesium oxide, mainly in the active form and partly in the bound state in the form of forsterite and magnesioferrite. This magnesia cement has a rather high strength, but requires high firing temperatures (up to 1400 ° C), it has a very significant linear shrinkage, in addition, this binder is most effective in the production of refractories.

A raw mixture for the manufacture of a magnesia binder is also known (RU 2089523, C 04 B 9/00), comprising dolomite and serpentinized ultrabasite at the following component ratio, by weight:

This mixture was baked at a temperature of 780 ° C. for 2 hours. The technical result achieved with the use of the invention is to shorten the time of setting and increase the adhesion to the wood.

The disadvantage of this solution is the low strength of the stone obtained when the binder is hardened, and also the limitation of the area of ​​use of the resulting binder (application only in the manufacture of wood-mineral products), which may be due to high shrinkage in the forming stone during hardening of the binder and the formation of cracks in the rigid System.

The astringent is known (SU 1433924, C 04 B 9/00), comprising components in the following ratio, by weight:

This binder provides excellent strength and linear shrinkage properties for hardening. The disadvantage is the additional energy expenditure for firing serpentine.

The closest to the claimed invention is the process according to RU 2245862 (C 04 B 35/03, C 04 B 9/06).

Production of talcum powder containing 73% magnesite, 20% talc, 5% chlorite and 2% other minerals, after coarse cleaning, crushing and sorting to a fraction of 0 ... 20 mm, is pre-dried, then fired for 3 hours in an oven at 900 ° C, is ground into a powder to a fraction of 0.08 mm to obtain magnesian binders. The resulting binder meets the requirements of GOST 1216-87. This method is considered economical, waste-free and environmentally safe.

However, astringent, used in construction, demands are made that differ from the requirements imposed on astringents for refractory materials. In addition, there is no data on the quality of products produced from the obtained materials: strength, cracking tendency for hardening and the magnitude of linear deformations. The claimed invention solves the problem of obtaining a magnesia binder for construction purposes from magnesian rocks with a high content of serpentinite, which are not suitable for the production of refractories having high strength, not prone to cracking and having low linear shrinkage during hardening.

The aim is achieved due to the fact that in the method for producing the magnesia binder, high-magnesian rocks containing hydrosilicates-serpentinites of 15-40 wt.%, Which are crushed to a fraction of less than 60 mm, are used as feedstock, are calcined at a temperature of 1050-1100 ° C for 2-3 hours, then grind into powder until passing through a sieve 008 - 78-84% by weight.

Crushing of the rock to a fraction of less than 60 mm ensures the least material loss during subsequent firing in a rotary kiln.

Firing at a temperature of 1050-1100 ° C for 2 ... 3 hours provides a magnesium astringent medium activity, characterized by high strength, small linear shrinkage and no tendency to cracking.

Thermal treatment of these magnesia rocks at lower temperatures (with the firing time up to 6 ... 8 hours) leads to the formation of astringent high activity, subject to cracking at the initial time of hardening and when exposed to water.

An increase in the temperature and time of roasting leads to a decrease in the activity of the main constituent of the binder, magnesium oxide, due to its crystallization and the transition to periclase, which can cause cracking of products based on the resulting binder at a later date, air hardening (this phenomenon can manifest itself within a year) Storage of samples in water (for 7 days).

The chemical composition of the initial rocks is given in Table 1, the mineralogical composition in Table 2.

The characteristics of the proposed magnesia binders are shown in Table 3.

From the data presented in the table it can be seen that the rocks of magnesite and brucite, including serpentinites in an amount of 15-40%, ensure the production of a quality binder only as a result of roasting at 1050 ... 1100 ° C and holding at these temperatures at least 2 and not More than 3 hours. Breeds that include insignificant iron impurities, for example brucites, after firing form a binder with high whiteness, which allows us to recommend its use for decorative decorative materials, mineral paints, putty.

To obtain building materials, the binder is thoroughly mixed with aggregates or without them for 1 ... 3 minutes and with an aqueous solution of magnesium chloride (bischofite) with a density of 1.2 g / cm ³ in an amount providing a molten mixture mobility, the mixture is poured into molds and Leave to harden at temperatures not lower than 10 ° C, preferably at 20 ... 25 ° C.

The invention makes it possible to expand the raw material base for the production of magnesia binder, incl. By recycling waste products of refractories. The invention can be used in the manufacture of slabs and panels for interior lining of buildings, window sills, staircases, and for the production of dry construction mixtures, heat insulating materials, monolithic floors, and the like.

Table 3
No.	Breed	Firing conditions	Properties
			Passage through a sieve 008,%	Propensity to crack formation *	R *, * MPa	***,%	Colour
1	Brucite	700 ° С 2 hours	76	Samples crack and disintegrate into blocks with air hardening		-	white
2	Magnesite		81	Samples crack and disintegrate into blocks with air hardening		-	gray
3	Brucite	800 ° С 2 hours	78	Samples crack and disintegrate into blocks with air hardening		-	white
4	Magnesite		83	Samples crack and disintegrate into blocks with air hardening			gray
5	Brucite	900 ° С 2 hours	75	Samples crack and disintegrate into blocks after 1 day of storage in water	24		white
6th	Magnesite		82	Samples crack and disintegrate into blocks after 1 day of storage in water	20	0.42	gray
7th	Brucite	1000 ° С 2 hours	78	Samples crack and disintegrate into blocks after 1 day of storage in water	56	0.21	white
8	Magnesite		82	Samples crack and disintegrate into blocks after 1 day of storage in water	55	0.18	gray
9	Brucite	1050 ° С 2 hours	78	Samples do not crack when stored for more than 7 days in water	74	0.03	white
10	Magnesite		80	Samples do not crack when stored for more than 7 days in water	77	0.025	gray
eleven	Brucite	1100 ° C for 2 hours	9	Samples do not crack when stored for more than 7 days in water	74	0.027	white
12	Magnesite		2	Samples do not crack when stored for more than 7 days in water	75	0.032	gray
13	Brucite	1200 '' 'From 2 hours	2	Samples have separate through cracks when stored for more than 2 days in water	42	-	white
14	Magnesite		4	Samples have separate through cracks when stored for more than 2 days in water	39	-	gray
* Cake samples made from a cement paste of normal density

CLAIM

A process for producing a magnesia binder, characterized in that high magnesian rocks containing 15-40% by weight of magnesium hydrosilicates are crushed to a fraction of less than 60 mm, baked at 1050-1100 ° C for 2-3 hours, then ground into a powder - Passage through a sieve 008 - 78-84%.

print version
Publication date 17.01.2007gg

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