Method of preparing anticorrosion pigment

FIELD: chemistry.

SUBSTANCE: invention relates to protection of metals from corrosion using lacquer coatings. The engineering problem is solved using a method of preparing an anticorrosion pigment based on aspiration dust wastes from foundry electric furnaces. The aspiration dust is mixed with calcium hydroxide in water with content of calcium hydroxide in the mixture with aspiration dust equal to 8-11 wt %, and aspiration dust with calcium hydroxide in water is taken in ratio of 1:1 respectively. The obtained mixture is dried, calcined at 820-900°C for 3.5-5.5 hours and then ground up to the required degree of dispersion.

EFFECT: possibility of simplifying preparation of a highly efficient anticorrosion pigment and without presence of toxic components in it, as well as reduction of cost of the pigment and environmental conservation.

1 cl, 2 tbl, 15 ex

 

The invention relates to the field of protecting metals from corrosion paints.

It is known that the main protective function in the system of coatings on metals perform primers, anti-corrosive action of which is largely determined by the content and type of pigments. The most effective in this aspect are anti-corrosive pigments and inhibitors present in the coating composition can suppress corrosion processes even in violation of their integrity. However, the most widely used pigments-inhibitors, such as chromium and lead, are highly toxic.

A group of anti-corrosive pigments, representing an environmentally friendly alternative to chrome - and swingersadelaidel pigments, are ferrites are mixed oxides of the spinel structure of the General formula MeO·Fe2O3where Me is magnesium, zinc, tin, copper, calcium, cadmium, cobalt, barium, strontium, iron, manganese, see the book Korsunsky L. F., Kalin T.V., S. Stepin. Inorganic pigments. Ref. ed. - SPb.: Chemistry, 1992. S.138; article: Freedom M Properties of ferrites zinc and calcium as anti-corrosive pigments. // Protection of metals. - 1988. - 24. No. 1. - P.44-47; Nepesov K.K., Guriev, L.N., Vasiliev PS Physico-chemical and protective properties of ferrites metals (calcium, magnesium, zinc). // G go active. chemistry. - 1991. - V.64. No. 2. - S-425; Corrosion-electrochemical properties of systems steel-ferrites alkaline earth metals. / CAS, Longoria, Laslau. // Fo. Protection-92), 6-11 Sept. 1992. EXT. proc. Dokl. - S.; Protective properties of some ferritic metals. / CAS, Longoria, Laslau. // Theory and practice. electrochim. processes and Ecol. aspects of their use. Proc. Dokl. The age of three. nauch.-practical use. Conf., Barnaul, 1990. - S. These pigments are related to corrosion, protects the metal by means of giving an alkaline reaction corrosive environment, penetrating to the metal.

A method of obtaining anti-corrosive pigment - ferrite of calcium - iron oxide and calcium, see U.S. Pat. France 2396051, IPC C09D 5/08, 1979.

Recently, however, due to the depletion of the resource base is a significant rise in anti-corrosive pigments, therefore, more attention has been paid to obtaining pigments from waste products, see Kotelnikov BORN and other coating materials and their application. 1998, No. 6, p.8-10, and Savelyeva GT and other coating materials and their application. 1997, No. 7-8, p.14-16. On the one hand, many of technogenic wastes contain valuable components, and create places of burial of environmental problems. In many cases, these wastes are characterized by high dispersion. is it eliminates the need for preliminary grinding and activation of their surface when carrying out heterogeneous reactions of synthesis on their basis. Therefore, their use in obtaining anti-corrosive pigments is a promising way of reducing their value.

The closest in technical essence of the present invention is a method for anticorrosive pigment-based waste galvanoplastics containing oxides of iron and calcium. Before using galvanoscope washed from water-soluble salts, followed by drying, calcination and grinding to the desired degree of dispersion, see Makarov V.I., Ladygina O.V., Indacin E.A. Ferrites of calcium-based galvanostatic - new effective anti-corrosion pigments. // Paint-and-lacquer materials. - 1999. No. 5. - P.3-4.

The disadvantage of this method is the presence of a stage of washing galvanostatic from water-soluble salts with subsequent recycling of the wash water, in addition, the composition of galvanostatic includes compounds of chromium, resulting in increased toxicity of pigment.

The task of the invention is to simplify the process of obtaining high-performance anti-corrosive pigment without the presence in its composition of toxic components and industrial waste.

The technical problem is solved in that in the method of obtaining anti-corrosive pigment-based waste production, including drying and calcining, and RA is saying to the desired degree of dispersion, as waste use waste electric furnaces foundry - suction dust, including, wt.%: Fe2O3- 63.9-70.0, FeO - 7.0-11.32, SiO2- 8.9-16, Al2O3- 1.45-3.12, which is mixed with calcium hydroxide in water at a mass ratio of the specified suction dust and calcium hydroxide, equal 89-92:8-11, respectively, and the mass ratio of the above-mentioned mixture and water is 1:1, respectively, dried, and calcined at 820-900°C for 3.5-5.5 hours

Technical solution allows for exceptions washing of raw materials to facilitate the production of high efficient anti-corrosive pigment, surpassing the prototype to measure the effectiveness of the protective effect under optimal conditions obtain at 7.5% and does not contain toxic components.

Suction dust electric furnaces foundry - waste electric arc remelting steel is a fine powder reddish-brown color (specific surface in the initial state up to 3400 m2/kg), previously used in polyvinylchloride composition as a coloring component. Polyvinylchloride composition used in the manufacture of molded specialized products for Windows and doors for the construction and repair of buildings.

The composition of the dust suction (baghouse dust) the components go, wt.%: Fe2O3- 63.9-70.0; FeO - 7.0-11.32; SiO2- 8.9-16; Al2O3- 1,45÷3,12; MnO - 1,35÷3,82; CaO - 1,37÷3,13; MgO - 1,21÷of 5.83, see patent RU 2210579, C08L 27/06, 2003.

The resulting pigment is a highly dispersible powder dark brown color.

For a better understanding of the invention examples of specific performance.

Example 1 specific synthesis of pigment

Anti-corrosive pigment was prepared as follows. In 100 g of water is mixed with 92 g (92 wt.%) suction dust with 8 grams (8 wt.%) calcium hydroxide, then remove the water by drying. The resulting product is calcined at a temperature of 820°C for 5 hours, and then ground to the desired degree of dispersion.

Examples 2-15 similar to example 1. Conditions for obtaining pigment are shown in table 1.

For evidence of corrosion properties of the synthesized pigments were investigated the interaction of their aqueous extracts with steel. As a comparison object used ferrite pigment derived from galvanic sludge firm LLC Feros", Yaroslavl.

Test for anti-corrosive properties was carried out as follows.

As the samples used body steel 08 KP. Before the corrosion test was carried out by the abrasive surface with the subsequent degreasing mineral spirits and acetone.

About isocorrosion properties of the pigments was estimated by current density corrosion of steel in the background electrolyte and the electrolyte from the aqueous extract of the pigment and the indicator of the protective effect of γ.

As the background electrolyte used a 3%aqueous solution of sodium chloride. Aqueous extract of pigments prepared in accordance with the methodology described in the book, see Iagellonicae, Day, Iautomate. Laboratory pigments and pigmented paints, varnishes and lacquers. L.: Chemistry, 1990, s.

15 g of the pigment is placed in a chemical glass with a capacity of 150-300 ml, poured cylinder 50 ml of distilled water, heated to boiling and boiled for 30 minutes, the Suspension is cooled, the filtrate is poured into the cylinder and bring the volume to 50 ml with distilled water, then mixed with an equal volume of a 6%aqueous solution of sodium chloride. The resulting electrolyte is used for testing the next day after cooking.

The current density of steel corrosion is found from potentiodynamic polarization curves taken on the potentiostat at a rate of 0.2 mV/s in the area of potential corrosion (±30 mV) according to the method described in the articles, see Elisavetskiy A.M., Warriors, VN, Vlasov V.V., Katalov V.I. calculation of the parameters of equations of the kinetics of corrosion processes. Paints, No. 6, 1997, p.26-28; Abrosimova L.A., Kayumov A.A., Svetlakov A.P., sparrows Y.S. Determining current corrosion computer processing of polarization curves. // Paints and coatings. Current status and development trends. With whom. articles of the all-Russian scientific-of Techn. proc. students and young scientists, December 2005. The cauldron. state technology. University, Kazan, 2005, s-103.

The index of the protective effect of the pigment is determined by the formulawhere i0the current density corrosion in 3%sodium chloride solution (background electrolyte); i1the current density corrosion in 3%solution of sodium chloride containing aqueous extraction of the pigment, see the book beetle I.E. the Course of theory of corrosion and protection of metals. M.: metallurgy, 1976, p.350.

Anticorrosive properties of the pigments are shown in table 2.

As can be seen from examples of specific performance obtained by the present method, the pigments in corrosion properties are not inferior to the pigment obtained according to the prototype, containing toxic chromium components. Under optimal conditions obtain (example 6) protective effect in comparison with the prototype above 7.5%. In addition, in the process of obtaining a pigment-based suction dust no waste water.

Thus, the inventive method allows to obtain a high-performance anti-corrosive pigment-based waste foundry without the presence of the pigment composition of toxic components and industrial waste in its production and thereby reduce the cost and save the environment.

6.72·10-7
Table 2
Anticorrosive properties of pigments
Number examplePigmentThe current density corrosion, A/cm2The index of the protective effect
A solution of sodium chloride1.62·10-5-
Prototype6.7·10-724
1The claimed object6.75·10-724.0
2the same6.61·10-724.5
3"-"6.67·10-724.3
4"-"6.72·10-724.1
5"-" 6.61·10-724.5
6"-"6.28·10-725.8
7"-"6.48·10-725.0
8"-"6.67·10-724.3
9"-"6.69·10-724.2
10"-"6.45·10-725.1
11"-"6.45·10-725.1
12"-"6.61·10-724.5
13"-"6.81·10-723.8
14"-"6.69·10-724.2
15"-"24.1

The method of obtaining anti-corrosive pigment-based waste production, including drying and calcining and grinding to the desired degree of dispersion, characterized in that as a waste use waste electric furnaces foundry - suction dust, including, wt.%: Fe2O363,9-70,0, FeO 7,0-11,32, SiO28,9-16, Al2O31,45-3,12, which is mixed with calcium hydroxide in water at a mass ratio of the specified suction dust and calcium hydroxide, equal 89-92:8-11, respectively, and the mass ratio of the above-mentioned mixture and water is 1:1, respectively, followed by drying, calcination at 820-900°C for 3.5 to 5.5 hours



 

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