RU2079474C1 - Method of refining natural minerals - Google Patents

Abstract

FIELD: jewelry. SUBSTANCE: invention relates to methods of treating natural minerals in order to improve their jewelry properties, in particular, charoites. Polished samples of charoite rock of various modifications are degreased with acetone or alcohol and dyed with 3-10% aqueous solution of active organic dye (active brilliantly violet 4KF, mixture of active red 6F and active turquoise K) with neutral electrolyte additive at 90 C for three days. Active dyes contain functional groups capable to form strong covalent bonds with samples. Dyes penetrate to a depth from 0.5 mm to full dyeing depending on structure and mineral constitution of samples. Acquired coloration is resistant to atmosphere conditions, water, soda, weak alkalis, acids, and temperatures up to 200 C. Dyeing does not fade in the sun and allows to preserve texture peculiarities of charoite. Treated samples of low-grade cheap charoite acquire intense violet color which confers them high jewelry quality. EFFECT: upgraded low-grade minerals. 3 cl, 1 tbl

Description

 The invention relates to methods for processing natural minerals in order to improve their jewelry qualities, in particular charoites.

 Known methods for coloring minerals with inorganic dyes, such as soluble salts of chromium, iron, cobalt, nickel, copper.

 Staining with inorganic compounds is accompanied by irreversible chemical reactions in the stone material with the formation of insoluble compounds resistant to atmospheric influences in the pore space.

 So, to stain agates and chalcedony in violet, a cobalt compound is used.

 However, a bright, stable, close to natural, color on charoite samples cannot be achieved by this method.

 Known and methods for the refinement of minerals based on the use of organic dyes.

 So, to enhance the color of turquoise samples, tinting it with aniline dyes or Prussian blue is used (A.N. Platonov, MN Taran, V.S. Balitsky. Nature of the color of gems. M. Nedra, 1984, p. 161 164).

 Organic dyes are also used to improve the color of pale jade samples (G. Smith. Gemstones. M. Mir, 1980, p. 450).

 However, after a few months, the artificial color is usually lost, and the necessary color effect for charoites cannot be achieved.

The closest technical solution to the invention is a method for staining natural jadeite with a solution of alcian green with pretreatment with an aqueous solution of nitric acid mixed with carbonic basic nickel at 90-100 ^° C, followed by fixing the color obtained with paraffin (a.s. N 502772, B 44 D 5 / 00, C 04 B 41/80, 1976).

 Treated in this way, samples of jadeite after treatment with an acid solution are covered with a thin network of etched intergranular gaps with a depth of 0.1-0.5 mm, into which the dye penetrates, staining off-grade jadeite in a bright green color, which is then fixed with paraffin.

 However, the known method is not suitable for charoite and charoite rocks for a number of reasons: firstly, the color achieved using alcian green does not correspond to the color necessary for charoite rocks; secondly, alcian green is an imported dye, and at present there are certain difficulties with its acquisition; thirdly, in the said prototype, the surface of jadeite samples is “etched” with nitric acid mixed with acidic nickel salt before painting to impart additional porosity to the painted surface.

 Charoite rocks requiring refinement are very heterogeneous in their mineral composition, they contain a large number of minerals (carbonates, sulfides, native minerals, etc.) that are soluble in an acidic environment, and an acidic environment would not only significantly violate their surface, but and would degrade the technological parameters of the breed.

 And finally, alcian green is a representative of phthalcyanine synthetic dyes, which are characterized by the properties of the main dyes. They are retained on the substrate mainly by ionic bonds, whose energy is of the order of 40–80 kJ / mol. And the greater the binding energy of the dye with the dyeing object, the more stable the color.

 The aim of the proposed method is to improve the jewelry properties of charoite.

This goal is achieved by the fact that polished samples of charoite rocks of various varieties are degreased with acetone or alcohol and stained with 3 10% solution of active organic dye at 90 ^o C. To improve the fixation of the dye, a neutral electrolyte, for example sodium chloride solution, is added to the dye solution.

 When degreasing a charoite sample, the residues of grinding oils are extracted from it, which contribute to the surface non-wettability, the maximum degree of pore openness and hinder the formation of covalent bonds of the dye and the sample.

 As coloring substances, use an aqueous solution of the active violet dye (TU 6-36-91-0-91) or a mixture of active red and blue dyes (TU 6-14-9992-85 and TU 6-36-5011400-11-89) .

 Active dyes are azo dyes (including complexes with transition metals Cu, Cr, Co), covering a gamut of colors from yellow to black.

 Active dyes contain functional groups capable of forming strong covalent bonds: E 110 630 kJ / mol. Dyes penetrate the samples to a depth of 0.5 mm to complete staining, depending on the structure and mineral composition of the sample.

 Samples belonging to the natural fibrous type of the banded-fibrous variety are stained over the entire depth.

 Samples containing in their mineral composition hard and dense grains such as quartz, aegirine and others in large quantities are stained with 0.5 1.0 mm.

 Samples are painted in various shades of intense purple. Visually, they become very similar in color to conditioned natural samples, which largely determines their cost.

 To fix the color, the samples are treated with an aqueous solution of a fixing agent of the type ДЦУ-2, У-2, Tanafix HM, Stabifix or a solution of acetic acid.

 Easy finishing of the samples on fine sandpaper and subsequent polishing on the felt with the use of polishing pastes give the samples shine.

The use of a 3-10% organic dye solution and simultaneous heat treatment at 90 ^o C for 3 days were established on the basis of numerous experiments using charoite samples of various varieties.

 It was found that at lower dye concentrations, a low processing temperature, and a shorter aging time, the color forms an unstable and unusual charoite in tone.

 When applying large concentrations of the dye, increasing the processing time, a noticeable increase and hardening of the violet color is not observed, and the color tone becomes very dark.

 When processed at higher temperatures, the color in the samples becomes dirty shades due to the partial decomposition of the organic dye solution.

 Example.

 Sanded charoite samples of light, whitish, dirty pinkish tones with various inclusions are washed with acetone and dried in air.

 Then it is placed in a closed vessel with a 5% solution of active bright violet 4kT dye and a solution of neutral electrolyte as a color fixer, for example, sodium chloride solution, is added.

Samples are kept in solution at 90 ^o C for three days.

 The stained samples are removed from the vessel, washed with water and dried.

 Then the samples are treated with a fixative solution at room temperature. After subsequent washing and drying, the samples are polished and polished.

 Charoite samples processed in this way acquire an intense purple color, which gives them high jewelry quality.

 The table shows the results of processing charoite samples with aqueous solutions of various active organic dyes.

Acquired by charoite samples, the color is resistant to weathering, water, soda, soap, weak alkalis and acids, temperature effects up to 200 ^o C, does not fade in the sun.

Claims (3)

1. The method of refinement of natural minerals by coloring using organic dyes, heat treatment and fixing the color, characterized in that the staining of charoite is carried out in 3 10% aqueous solutions of active organic dyes with the addition of a neutral electrolyte at 90 ^o C for 3 days.  2. The method according to claim 1, characterized in that the active dye violet 4 kT is used as a dye.  3. The method according to claim 1, characterized in that as a dye using a mixture of active red 6F and active turquoise K.

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