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CONSTRUCTION MATERIALS. CONSTRUCTION COMPOSITIONS, MIXTURES AND COMPOSITIONS FOR MANUFACTURING BUILDING MATERIALS AND CONSTRUCTION OF CONSTRUCTION WORKS
INVENTION
Patent of the Russian Federation RU2081087

MASS FOR MANUFACTURE OF BUILDING PRODUCTS AND METHOD OF ITS PRODUCTION

The name of the inventor: Sereda AB; Kalinichenko II; Popov BA; Goryainov V.E .; Sereda BP; Smirnov S.V .; Kominova LV; Lekanov L.P.
The name of the patent holder: Joint-stock company "Hrompik"
Address for correspondence:
The effective date of the patent: 1995.01.17

The invention relates to the production of building products based on a magnesia-gypsum binder, in particular, to the production of building products based on the waste of production of monochromate sodium-waste sludges of chromate production and can be used in enterprises producing building materials or in chrome plants. The object of the invention is the utilization of waste slurries of chromate production with the simultaneous production of building materials on its basis, the expansion of their use due to non-toxic mass, the improvement of the quality of products and the reduction in the cost of the process. The invention consists in the fact that the mass for the manufacture of building products consists of a mixture of detoxified chromate slurry, organic filler, sulfuric acid and water with the following proportions of components, by weight: chromium slurry 46.0-61.0; Sulfuric acid - 11.0-21.5; Organic filler - 4,0-10,0; Water - the rest. The method for producing a mass for the manufacture of building products is that a chromate slurry in an amount of 20-50% by weight of the original is mixed with water in a weight ratio providing T: M in a mixture of 1: 1 to 3, respectively, acid is introduced from the weight ratio Sludge of magnes. : H 2 SO 4 in the range 0.9-1.65 and after stirring the reaction mixture for 20-60 minutes at a temperature of 80-90 ° C., the organic filler and the rest of the slurry are introduced into the obtained magnesia-gypsum binder and the resulting mass Dried to a moisture content of 5-15% by weight, molded and cured. To prevent the reverse process of chromium (III) transition from the water-insoluble state into the chromium (VI) compounds, a sulfur-containing reducing agent in an amount of 0.1-0.5% by weight of the introduced slurry can be introduced into the mass. Sulfur, sulfide, sulfite or sodium thiosulfate is used as sulfur reducing agents.

DESCRIPTION OF THE INVENTION

The invention relates to the production of building products based on a magnesia-gypsum binder, in particular, to the production of building products based on the waste of monochromate sodium production of waste slurries of chromate production and can be used in enterprises producing construction materials or in chrome plants.

A mass is known for road construction, consisting of waste slag of chromate production and sulphite-bardy concentrates [1]

A mass is known for the production of refractory materials, cement and silicate bricks, consisting of chromate sludge and sand [1]

The main drawbacks of the known compositions include the substantial limited use of products made on the basis of waste chromate slurries containing hexavalent chromium compounds.

A method is known for producing a mass for the production of silica brick, which consists in that the chromate slurry is preliminarily hydrothermally treated to hydrate magnesium oxide, mixed with sand and subjected to compression at a pressure of 160-200 kgf / cm 3 [1]

The disadvantages of the known masses and methods for their production are low efficiency and limited use of finished products.

The closest to the intended, is the mass for the manufacture of cement, containing, by weight. 42-94 active magnesium oxide, 5-38 magnesium sulfate, which can be mixed with magnesium chloride, 1-20 organic filler, which is a wood pulp and / or inorganic filler, which is glass fiber [2]

A process for preparing a known mass comprises mixing an aqueous solution of magnesium sulfate (or magnesium sulphate and chloride) and a filler with magnesium oxide. The resulting products are used mainly for the production of building materials that have a small mass, incombustibility and good thermal insulation properties [2]

A disadvantage of the known mass and method of its manufacture is that its composition includes relatively scarce and relatively expensive components, for example, such as active magnesium oxide and salts of the latter, which significantly increases the cost of manufactured construction products.

The technical problem of the invention is the utilization of waste slurries of chromate production with the simultaneous production of building materials on its basis, the expansion of the field of application of the latter due to the production of a nontoxic mass, the improvement of the quality of products and the reduction in the cost of the process.

The problem is achieved by the fact that the claimed mass and the method for its preparation differ from the known solution in that a chromium-containing slime, previously neutralized (free of hexavalent chromium compounds), is used as the magnesium-containing compound and inorganic filler.

The process of detoxification of chromate slurry is that the chromium (VI) present in it is converted to chromium (III) compounds. This is achieved by treating it in an alkaline solution with sulfur-containing reducing agents at 120-160 ° C. In this case, the chromium (VI) compounds, both water- and acid-soluble, become water-insoluble compounds of chromium (III).

The slime of chromate production is a large-capacity unutilized waste of chrome plants. The composition of the latter can be represented by such basic mineral phases and products of their hydration as aluminates, hydroaluminates, chromato-aluminates, silicates, calcium aluminoferrites, magnesium oxide, magnesium hydroxide, aluminum, calcium, sulfates and chromates of calcium, sodium, etc. In dry sludge Chromate production is contained, in terms of oxides, wt. 2-3.7 CrO 3 , 7-9 Cr 2 O 3 , 23-28 MgO, 28-32 CaO, 10-12 Fe 2 O 3 , 6-8 Al 2 O 3 , 4-6 SiO 2 [1, P.104, 113]

As the organic filler, cellulose-containing raw materials are used, for example, wood pulp produced according to GOST 18110-72 or sawing waste, or lignin-containing raw materials, for example, hydrolytic lignin. The composition and properties of the latter are described in the monograph.

The essence of the invention consists in the fact that the mass for the manufacture of building products consists of a mixture of a magnesium-containing compound, an inorganic and organic filler, sulfuric acid and water, with the neutralized chromium slurry being used as the magnesium-containing compound and inorganic filler at the following component ratios, Slime of chromate production 46,0-61,0; Sulfuric acid - 11.0-21.5; Organic filler 4,0-10,0; Water the rest.

The method of obtaining a mass for the manufacture of construction products is that the chromate slurry in an amount of 20-50 wt. From the initial (the so-called magnesium sludge) is mixed with water in a mass ratio providing T: G in the mixture in the range 1: 1-3, the acid is introduced from the mass ratio of the sludge of magnesium: H 2 SO 4 in the range of 0.9-1, 65 and after stirring the reaction mixture for 20-60 minutes at a temperature of 80-90 ° C., the organic filler and the rest of the slurry (so-called slurry feed) are introduced into the obtained magnesia-gypsum binder; The resulting mass is dried to a moisture content of 5-15 wt. Mold and cure. To prevent the reverse process of chromium (III) transition from the water-insoluble state to the chromium (VI) compounds, a sulfur-containing reducing agent can be introduced into the mass. As sulfur-containing reducing agents sulfur, sulfite, sulfite or sodium thiosulfite is used. The reducing agent is introduced in an amount of 0.1-0.5 wt. From the introduced slurry.

The comparative evaluation of the proposed and known mass for the manufacture of construction products and the method of its production allows us to identify the following distinguishing features: the qualitative and quantitative composition of the claimed mass and the order and modes of the method for obtaining the claimed mass.

All of the foregoing allows us to conclude that the claimed invention complies with the criterion of "Novelty."

In the scientific and technical literature, methods for the preparation of building products are described, based on the introduction into the composition of raw materials for the manufacture of building materials (for road construction, silicate brick, cement, etc.) waste sludges of chromate production. However, the use of the invention makes it possible to obtain articles that do not contain toxic hexavalent chromium and are characterized by increased density and mechanical strength. This effect is ensured by the use of detoxified slag of chromate production, on the one hand, and magnesia-gypsum binder, obtained on its basis and representing a mixture of water-soluble and insoluble products of sulfuric acid decomposition of chromate slime, on the other.

Synthesis of the magnesia-gypsum binder is carried out by sulfuric acid decomposition of a part of the slime of chromate production in an amount of 20-50 wt. From the starting at a temperature of 80-90 ° C for 20-60 minutes. The completeness of the interaction of sulfuric acid with the slurry, achieved with the claimed process parameters and ensuring a high degree of decomposition of its mineral phases, leads to a sufficiently reaction mixture of the magnesia-gypsum binder. Subsequent mixing with filler ensures a uniform distribution of the filler in the magnesia-gypsum binder and makes it possible to obtain the raw material of sufficient plasticity. Along with a uniform distribution of binder and fillers, a sufficient density and mechanical strength of the products obtained during the formation and subsequent curing are provided.

Thus, the proposed mass for the manufacture of construction products and the method of its production contains a number of new features that, in our opinion, provide a new technical result, namely: the production of non-toxic cheap products of improved quality. This allows us to conclude that the claimed solution meets the criterion of "Inventive level".

The following are examples of the implementation of the invention.

Used neutralized slime chromate production, does not contain hexavalent chromium, composition, weight. 30.2 CaO, 25.2 MgO, 10.4 Fe 2 O 3 , 7.1 Al 2 O 3 , 5.2 SiO 2 , 9.2 Cr 2 O 3 .

A sample of air-dry sludge in an amount of 20-50% of the initial sludge to obtain a magnesia-gypsum binder is mixed with a predetermined amount of water from a T: F mass ratio of 1: 3 to obtain an aqueous slurry which is placed in a stirred and heated reactor and heated To 80-90 o C. After reaching the set temperature, sulfuric acid is introduced into the suspension with constant stirring in an amount providing a mass ratio of the magnesium sludge . : An acid within the range of 0.9-1.65.

The reaction mixture is stirred for 20-60 minutes to obtain a so-called magnesia-gypsum binder. The latter is then transferred to a laboratory twin-shaft electric-heated mixer, into which a filler and a sulfur-containing reducing agent selected from the following substances: sulfur, sulfide, sulfite or sodium thiosulfate are sequentially introduced. Wood pulp or lignite as an organic filler is introduced in an amount of 20-60 wt. From the sample of sludge . , While the inorganic amount of sludge / sludge, ie, 20-80% of the original sludge. The amount of reducing agent is 0.1-0.5 wt. From chromate slime.

Mass ratio of sludge of magnesium . : Slam nap. In the raw material being prepared, the change is in the range from 1: 1 to 1: 4. The latter is thoroughly mixed and with a moisture content of 5-15 wt. From it on a lab press at a compaction pressure of 150-200 kg / cm 2, samples are formed with a diameter of 1 cm and a height of 0.8-1.0 cm, which are then cured, held in air at room temperature, after which the compressive strength is determined, Using the same press.

The results are shown in Table 1.

MASS FOR MANUFACTURE OF BUILDING PRODUCTS AND METHOD OF ITS PRODUCTION

Strength values ​​are given for samples cured in air for 7 days.

Products made from the proposed mass are characterized by sufficient high mechanical strength at an apparent density in the range of 1.624-2.213 g / cm 3 .

Comparative evaluation of the target product made on the basis of the proposed magnesia-gypsum binder (Table 1) and magnesium compounds (oxide, sulfate, magnesium chloride) used in the known prototype method (Table 2) showed that the known binder does not give Effect in the case of using as a filler slurry chromate production.

The choice and justification of the claimed parameters is due to the following.

Maintaining in the declared limits of the mass ratio T: M in the aqueous slurry of the slurry entering the acidic interaction, and the temperature and time parameters of the process provides 90-95% decomposition of the magnesium compounds of the slurry and the production of the magnesia-gypsum binder, the water-soluble part of which is represented by magnesium sulfate (60-100 g / l MgSO 4 ), and calcium compounds (0.7-2 g / l CaO), silicon (0.6-1.9 g / l SiO 2 ), aluminum (0.2-1 , 5 g / l Al 2 O 3 ) and iron (0.6-0.8 g / l Fe 2 O 3 ), insoluble by calcium sulphate and mineral phases of the original sludge.

When the content of the magnesia-gypsum binder in the claimed mass decreases (decrease in the ratio of the sludge of magnesium: sludge), the plasticity and formability of the mass deteriorate, and the mechanical strength of the products is reduced. This is due to the fact that sufficient wettability of the mass components and the filling of the smallest pores in it is not achieved, on the one hand, and the pressing effect (molding) is reduced, on the other. An increase in its content is higher than the upper limit, that is, an increase in the mass ratio of the sludge of magnesium . : Slime feed . In the raw material being prepared, it is economically impractical, because Increase the consumption of acid and the cost of decomposition of sludge.

As an organic filler, wood pulp and lignin are used. Introduction of it above the upper limit reduces the molding capacity of the claimed mass and the strength of the product obtained from it. The moisture content of the mold during molding is maintained in the range of 5-15 wt. Lowering the humidity below the lower limit reduces the effect of pressing (forming) at a given pressure; With an increase above the upper, moreover, it is associated with considerable difficulty in pressing and shrinking the articles upon curing.

CLAIM

1. A mass for the manufacture of building articles containing a magnesium-containing compound, inorganic and organic fillers and water, characterized in that as a magnesium-containing compound and an inorganic filler, it contains a neutralized chromate slurry and additionally sulfuric acid with the following component ratio,

Neutralized slime of chromate production 46 61

Sulfuric acid 11.0 21.5

Organic filler 4 10

Water Other

2. A method for producing a mass for the manufacture of building articles by preparing an aqueous solution of magnesium-containing raw material, mixing the solution with organic and inorganic fillers, followed by drying the resulting mixture, characterized in that a neutralized slime of chromate production in the amount of 20 50 is used to prepare the magnesium-containing raw material in the aqueous solution Wt. From the starting material, sulfuric acid is introduced into the aqueous slurry with stirring and heating, and the organic magnesia and the rest of the chromium slurry are subsequently introduced into the resulting magnesia-gypsum binder.

3. A method according to claim 2, characterized in that the chromate slurry is mixed with water in a weight ratio providing T F in a mixture of 1 to 3, respectively.

4. The method of claim 2, wherein sulfuric acid is introduced from the calculation of the slurry acid mass ratio in the range of 0.9 to 1.65.

5. A process according to claim 2, characterized in that the sulfur content of the reducing agents selected from the group sulfur or sulfide, sodium sulphite or sodium thiosulfate is introduced in an amount of 0.1 to 0.5% by weight. From the introduced slurry.

6. A process according to claim 2, characterized in that the reaction mixture is treated with sulfuric acid at 80 ° -90 ° C. for 20-60 minutes.

7. A process according to claim 2, characterized in that the inorganic filler-the rest of the slurry is added based on the weight ratio of the sludge of magnesium .

Sludge nap. 1 1 1 3.

8. A method according to claim 2, characterized in that the obtained raw material is dried before drying to a humidity of 5 to 15% by weight.

print version
Date of publication 18.12.2006гг