High-purity purification preparation method of lapis lazuli pigment

Abstract

The invention discloses a high-purity purification preparation method of lapis lazuli pigment, and relates to the technical field of mineral pigment preparation. The method comprises the following steps: preparing materials (weighing lapis lazuli powder, beeswax, resin and rosin according to a ratio of 4: 1: 1: 2), mixing and heating to a liquid state, cooling and air-drying for 5-7 days, scrubbing with alkaline water (warm alkaline water at 40-45 DEG C for 1 hour), dewaxing with boiling water, cleaning with ultrasonic waves, and drying the powder. The embodiment verifies that the purity of particles of 350 meshes or above of the purified lapis lazuli pigment reaches 85%-90%, the color saturation is improved by 32%, and the application requirements of traditional art are met. The method is simple and convenient to operate, solves the problems of low purity of lapis lazuli pigment, especially insufficient color of fine particles of 350 meshes or above in the prior art, and can effectively improve the quality of the pigment.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of mineral pigment preparation, and particularly relates to a high-purity purification preparation method of lapis lazuli pigment. BACKGROUND

[0002] As a natural mineral pigment, lapis lazuli pigment has an irreplaceable position in rock varnish and mural painting, and its color is praised as "color phase like heaven". Traditional murals such as Dunhuang murals rely on high-purity lapis lazuli to achieve artistic effects, but currently, lapis lazuli pigments used in China mostly rely on imported raw stones from Afghanistan, which are processed into pigments through simple processes such as crushing, grading and water flying. In the prior art, lapis lazuli is prepared by a single grinding method, that is, through the steps of ore dressing, crushing and coarse grinding (80-100 mesh), washing and grading, magnetic separation to remove iron filings, acid washing to remove impurities, and finally drying the powder. Although this method can obtain basic pigments, it lacks effective purification processes, resulting in insufficient pigment purity, especially the color phase purity of fine particles above 350 mesh, which is as low as 60%-70%, which cannot restore the deep blue tone in traditional murals, affecting artistic restoration and cultural heritage.

[0003] The prior art is a simple crushing and grading method, which includes the following steps: removing impurities by ore dressing, crushing and coarse grinding to 80-100 mesh, washing and grading by water flying, magnetic separation to remove iron filings, acid washing to dissolve carbonate impurities, and finally drying the powder. However, this method has significant drawbacks: poor purification effect, mineral impurities remaining on the surface of lapis lazuli particles, low blue value, and inability to meet the needs of high-precision artistic creation. For example, the color phase purity of 350 mesh lapis lazuli fine particles is only 65%, resulting in dull colors when copying murals, and the acid washing process may introduce chemical residues, reducing the safety of the pigment.

[0004] Lapis lazuli pigment raw materials are valuable (top-grade Afghan lapis lazuli costs tens of thousands of yuan per kilogram), and the prior art does not solve the problem of purification, making high-purity preparation processes almost lost. This not only restricts the development of rock varnish and mural painting, but also affects the protection of cultural heritage. Therefore, there is an urgent need for an efficient purification method that optimizes material ratios and processes to improve the purity and color beauty of lapis lazuli, especially fine particles, while also considering process feasibility. SUMMARY

[0005] The technical problem to be solved by the present application is to overcome the above-mentioned defects of the prior art, and to provide a preparation method that optimizes material ratios and processes to improve the purity and color beauty of lapis lazuli, especially fine particles.

[0006] The technical solution adopted by the present application to solve its technical problem is as follows:

[0007] A high-purity purification preparation method of lapis lazuli pigment, comprising the following steps,

[0008] (S1) Material weighing, accurately weigh the malachite powder, beeswax, resin, and pine resin according to the mass ratio of 4:1:1:2;

[0009] (S2) Melt mixing, heat the beeswax, resin, and pine resin to 80-85℃ to melt into a liquid state, after stirring, add the malachite powder, and continue stirring until a uniform slurry is formed;

[0010] (S3) Filtration and molding, pour the slurry into a non-stick plate after filtration, cool to room temperature to solidify, roll into a long strip and segment;

[0011] (S4) Air drying and solidification, segment the material in a well-ventilated environment and air dry for 5-7 days, turn over and knead every day;

[0012] (S5) Purification with alkaline water, knead the dried material in warm alkaline water at 40-45℃ for 60 minutes, the alkaline water is a 0.5-1wt% sodium carbonate aqueous solution, replace the alkaline water every 20 minutes;

[0013] (S6) Dewaxing and refining, after purification, move the material to boiling water for 5 minutes to remove wax, and then wash with 40kHz ultrasonic wave for 10 minutes;

[0014] (S7) Drying, low-temperature drying at 60℃ until the water content is ≤2%, obtaining the purified malachite pigment.

[0015] The above-mentioned high-purity purification preparation method of malachite pigment, preferably, the heating temperature in step (S2) is strictly controlled at 80-85℃, a temperature lower than 80℃ leads to insufficient dissolution of the resin, and a temperature higher than 85℃ initiates carbonization of the pine resin.

[0016] The above-mentioned high-purity purification preparation method of malachite pigment, preferably, a 200-mesh stainless steel screen is used for filtration in step (S3) to intercept undispersed mineral aggregates. The present application precisely intercepts >75μm mineral aggregates, eliminating the optical interference of pyrite.

[0017] The above-mentioned high-purity purification preparation method of malachite pigment, preferably, the air drying environment in step (S4) has a humidity of ≤40%, and the material is kneaded 3 times a day to promote the formation of internal microcracks, mechanical force induces directional microcracks (depth 5-10μm), and improves the penetration efficiency of alkaline water.

[0018] The above-mentioned high-purity purification preparation method of malachite pigment, preferably, during the kneading operation in step (S5), the hands are smeared with linseed oil to reduce the adsorption loss of the material surface. An oil film barrier is used to reduce the adsorption loss of fine particles and improve the yield.

[0019] Preferably, in the step (S6), the ultrasonic cleaning is performed by using a stepwise temperature program, i.e., first cleaning at 25 DEG C for 2 minutes, then cleaning at 40 DEG C for 5 minutes, and finally cleaning at 55 DEG C for 3 minutes. The temperature gradient of the present application can dissolve the wax-impurity complex, and avoid local overheating degradation.

[0020] The preparation method of the present application can form a complex coating layer by melting the resin with a specific acid value, beeswax with a saponification value of 85-100 mgKOH / g and pine resin at a precise temperature of 80-85 DEG C to coat the impurities of the pretreated lapis lazuli powder; after removing the mineral agglomerates by filtering through a 200 mesh metal screen, dynamic air drying (assisted by mechanical kneading and pressing) is performed in an environment with a humidity of ≤40%, to induce the formation of oriented microcracks with a density of ≥12 strips / mm 2 ; then, the impurities are efficiently dissolved in warm alkaline water at 40-45 DEG C by using the microcrack channels, and finally, the wax-impurity complex is completely stripped by using a stepwise temperature ultrasonic program (25 DEG C→55 DEG C), so that the purity of the lapis lazuli particles with a size of more than 350 meshes is increased to 85%-90%, the CIE b* value is ≤-40, and the color index is restored to the standard of traditional mural pigments.

[0021] The lapis lazuli pigment high-purity purification preparation method has the following advantages: preferably, the final product meets the following indexes: the proportion of particles with a size of more than 350 meshes is ≥95%; the CIE b* value is ≤-40 under D65 light source; and the content of non-lapis lazuli mineral impurities is ≤2%.

[0022] The present application has the following advantages:

[0023] (1) The present application can increase the purity of lapis lazuli pigment with a size of more than 350 meshes to 85%-90% by using resin-beeswax complex coating (precise temperature control at 80-85 DEG C) and stepwise ultrasonic dissociation technology, and solve the industry problem of impure color of fine particles;

[0024] (2) The present application can block the color development interference of impurities by using the complex coating layer, so that the CIE b* value is ≤-40 (D65 light source), the saturation is increased by more than 30% compared with the raw material, and the traditional beauty of "color like the sky" is restored;

[0025] (3) The present application can form oriented microcracks with a density of ≥12 strips / mm2 by using dynamic air drying (humidity ≤40% and mechanical kneading and pressing), so that the penetration efficiency of alkaline water is increased by 220%, and the calcite residue is reduced to <0.5%;

[0026] (4) The present application can realize the synergistic effect of 200 mesh filtering and stepwise ultrasonic (25 DEG C→55 DEG C), so that the pyrite residue is ≤0.1%, and the wax stripping rate is >99%;

[0027] (5) The present application does not involve strong acid in the whole process, the alkaline washing liquid can be recycled, the purity deviation of 10 times magnification production batch is <0.5%, and the energy consumption is reduced by 40%. BRIEF DESCRIPTION OF DRAWINGS

[0028] Figure 1 is a flow chart of a high-purity purification method of lapis lazuli pigment in the present application. DETAILED DESCRIPTION

[0029] In order to facilitate the understanding of the present application, the following will be a more comprehensive and detailed description of the present application in combination with the preferred embodiments, but the protection scope of the present application is not limited to the following specific embodiments.

[0030] Unless otherwise defined, all the professional terms used in the following have the same meaning as generally understood by those skilled in the art. The professional terms used in the present application are only for the purpose of describing the specific embodiments, and are not intended to limit the protection scope of the present application.

[0031] Unless otherwise specified, various raw materials, reagents, instruments and equipment used in the present application can be purchased from the market or can be prepared by existing methods.

[0032] Example 1

[0033] Reference Figure 1 A high-purity purification method of lapis lazuli pigment in the present application includes the following steps,

[0034] (S1) Material weighing, weighing 400g of lapis lazuli powder, 100g of bleached beeswax with a saponification value of 95mgKOH / g, 100g of mastic resin with an acid value of 4mgKOH / g, and 200g of dust-free pine resin;

[0035] (S2) Melt mixing, place the beeswax, resin and pine resin in a porcelain bowl and melt at 83℃±1℃ for 30 minutes, then add the lapis lazuli powder after stirring to liquid state, and continue stirring to form a uniform slurry;

[0036] (S3) Filtration and molding, the slurry is filtered through a 200-mesh stainless steel screen to remove >75μm agglomerates, then poured onto a non-stick plate and cooled to room temperature to solidify, rubbed into 2cm diameter strips and cut into 10cm segments;

[0037] (S4) Air drying and curing, the segmented material is placed in a 35% humidity and ventilated environment, and manually kneaded 3 times a day for 6 days to form microcracks;

[0038] (S5) Alkaline purification, immerse the air-dried material in 42℃ warm alkaline water containing 0.8wt% sodium carbonate, and knead for 60 minutes after rubbing with linseed oil with both hands, and replace the alkaline water every 20 minutes;

[0039] (S6) dewaxing and refining, the material is transferred into boiling water and boiled for 5 minutes, and then put into a 40 kHz ultrasonic cleaning machine and cleaned according to a ladder program of 25 DEG C / 2 min→40 DEG C / 5 min→55 DEG C / 3 min;

[0040] (S7) drying, dried in a 60 DEG C oven until the water content is 1.8%, and high-purity lapis lazuli pigment is obtained.

[0041] It is detected that the purity of the high-purity lapis lazuli pigment prepared in the embodiment reaches 88% (65% of raw material), the blue value b* is -42.5 (the raw material is -32.1), the color saturation is improved by 32%, the calcite residue is reduced to 0.3% (5.8% of raw material), and the pyrite residue is less than 0.1%. 83 DEG C melting forms a hydrogen bond wrapping layer (wrapping rate 92%) of resin-bee wax, 200 mesh filtering removes >75 μm agglomerates, and humidity 35% air drying combined with kneading generates 18 strips / mm 2 microcracks, and the alkali water penetration rate reaches 0.32 mm / min, which is improved by 220% compared with the conventional process. The final pigment particle size distribution is concentrated (D90=68 μm), and the water content is 1.8%, which meets the traditional fresco color standard.

[0042] Example 2

[0043] A high-purity lapis lazuli pigment preparation method of the present application comprises the following steps,

[0044] (S1) material weighing, same as the raw material ratio of example 1;

[0045] (S2) melting and mixing,

[0046] Group A, 78 DEG C melting, resin is not completely dispersed;

[0047] Group B, 83 DEG C melting;

[0048] Group C, 88 DEG C melting, pine resin is slightly carbonized;

[0049] (S3) filtering and forming, same as example 1, 200 mesh stainless steel screen is used for filtering;

[0050] (S4) air drying and solidification, A / C group is placed in a humidity 45% environment, B group is placed in a humidity 35% environment, and both are air dried for 6 days;

[0051] (S5) alkali water purification, rubbing for 60 minutes at 42 DEG C warm alkali water, and changing water twice;

[0052] (S6) dewaxing and refining, the material is transferred into boiling water and boiled for 5 minutes, and then put into a 40 kHz ultrasonic cleaning machine and cleaned according to a ladder program of 25 DEG C / 2 min→40 DEG C / 5 min→55 DEG C / 3 min;

[0053] (S7) drying, drying in an oven at 60°C, comparing the performance difference of three groups.

[0054] It is detected that the embodiment verifies the influence of critical parameters on performance, B group (standard 83°C): purity 88%, b*-42.5, calcite residue 0.3%, consistent with example 1; A group (78°C): due to insufficient resin melting, the wrapping rate is only 61%, the purity drops to 72%, b* is-36.2, and the calcite residue rises to 3.1%; C group (88°C): the gray degree increases due to the carbonization of turpentine, the purity drops to 68%, b* is-34.8, and the carbonized impurities account for 12%. Under the humidity of 45% in the A / C group, the microcrack density is only 5 / mm 2 (B group 18 / mm 2 ), and the residual calcite after alkali washing is 8.5%. The data prove that the temperature of 80-85°C and the humidity of ≤40% are the process threshold.

[0055] Example 3

[0056] A method for preparing a high-purity lapis lazuli pigment according to the present application, comprising the following steps,

[0057] (S1) material weighing, weighing lapis lazuli powder 400g, saponification value 95mgKOH / g bleached beeswax 100g, acid value 7mgKOH / g frankincense 100g, and dust-free pine resin 200g;

[0058] (S2) melting and mixing, melting beeswax, frankincense and pine resin at 83°C for 30 minutes, and adding lapis lazuli powder after stirring to liquid state;

[0059] (S3) filtration and forming, continuously filtering the slurry through three layers of 200-mesh stainless steel mesh, and cooling and sectioning by rolling;

[0060] (S4) air drying and curing, placing in a humidity of 35%, mechanically kneading and pressing once every 2 hours, and air drying for 6 days;

[0061] (S5) alkali purification, immersing the air-dried material into 42°C warm alkali water containing 0.8wt% sodium carbonate, rubbing for 90 minutes after rubbing with linseed oil by both hands, and replacing the alkali water every 30 minutes;

[0062] (S6) de-waxing and refining, transferring the material into boiling water and boiling for 5 minutes, then putting into a 40kHz ultrasonic cleaning machine, and cleaning according to the ladder program of 25°C / 2min→40°C / 5min→55°C / 3min;

[0063] (S7) drying, drying in an oven at 60°C to a water content of 1.8%, and obtaining the purified lapis lazuli pigment.

[0064] The high-purity lapis lazuli pigment prepared in this embodiment has a purity of 85%, a blue value b* of -41.0, and an acid residue of 2.8%. Three layers of 200-mesh filters are used to remove agglomerates (>75 μm) caused by uneven dispersion of frankincense, and the residual is reduced to 0.6%; intensive kneading (once every 2 hours) maintains the microcrack density at 15 lines / mm 2 ; the yield of 350-mesh particles is 95% under the protection of linseed oil. Although the purity is slightly reduced, the color performance meets the demand for fresco copying, confirming that resins with an acid value of ≤5 mgKOH / g can be expanded to frankincense.

[0065] Example 4

[0066] A method for preparing high-purity lapis lazuli pigment according to the present application, comprising the following steps,

[0067] (S1) Material weighing, scaling up by 10 times, lapis lazuli 4 kg, beeswax 1 kg, mastic resin 1 kg, pine resin 2 kg;

[0068] (S2) Melt mixing, melt the materials in a sandwich reaction kettle at a constant temperature of 83℃±0.5℃, with a stirring rate of 30 rpm;

[0069] (S3) Filtering and forming, after mixing, the slurry is pumped into a 200-mesh stainless steel vibration screen machine, with an amplitude of 2 mm and a frequency of 50 Hz, and the material is automatically cut into strips;

[0070] (S4) Air drying and solidification, the strips are placed in a constant humidity room with a humidity of 35%, and a mechanical arm kneads the strips once every 4 hours with a pressure of 5±0.3 N, and the strips are air dried for 7 days;

[0071] (S5) Purification with alkaline water, in a circulating temperature-controlled alkaline washing tank, the temperature is 42±0.5℃, the belt speed is 0.2 m / min, and the total processing time is 60 minutes;

[0072] (S6) Dewaxing and refining, a series of ultrasonic units are used for continuous treatment in three temperature zones of 25℃→40℃→55℃, with a total time of 10 minutes;

[0073] (S7) Drying, fluidized bed dryer at 60℃ to dry to a moisture content of 1.8%.

[0074] The high-purity lapis lazuli pigment prepared in this embodiment has excellent batch consistency, with a purity of 87.5% and a b* of -42.2 in the first batch, and a purity of 88.1% and a b* of -42.4 in the second batch, and a stable moisture content of 1.9%. The sandwich reaction kettle has a temperature control of ±0.5℃, which makes the thickness deviation of the wrapping layer less than 0.2 μm; the mechanical arm kneading (5N±0.3N) ensures the microcrack density at 17-19 lines / mm 2; vibration sieve removes >75μm agglomerates (0.4% residual). The series connection of ultrasonic units reduces the specific energy consumption by 40%, and the impurity residue is still ≤0.35% (calcite <0.2%, pyrite <0.1%) under 10 times production, verifying the scalability of the process.

[0075] Comparative Example 1

[0076] A method for purifying lapis lazuli according to the present comparative example, comprising the following steps,

[0077] (S1) Material weighing, weighing lapis lazuli powder 400g, bleached beeswax with saponification value 95mgKOH / g 100g, martis resin with acid value 4mgKOH / g 100g, and dust-free pine resin 200g;

[0078] (S2) Melt mixing, place the beeswax, resin, and pine resin in a porcelain bowl and melt at 83℃±1℃ for 30 minutes. After stirring to a liquid state, add the lapis lazuli powder and continue stirring to form a uniform slurry;

[0079] (S3) Filtration and molding, filter the slurry through a 200-mesh stainless steel screen to remove >75μm agglomerates, then pour it onto a non-stick plate and cool to room temperature to solidify, roll it into a 2cm diameter strip and cut it into 10cm segments;

[0080] (S4) Air drying and solidification, place the segmented material in a humidity-controlled environment (humidity 60%) for 7 days without kneading and pressing;

[0081] (S5) Alkali purification, immerse the air-dried material in 42℃ warm alkali water containing 0.8wt% sodium carbonate, and knead for 60 minutes after applying linseed oil with both hands. Replace the alkali water every 20 minutes;

[0082] (S6) Dewaxing and refining, transfer the material to boiling water and boil for 5 minutes, then immerse it in 40kHz single-temperature ultrasonic cleaning for 10 minutes (25℃ constant temperature);

[0083] (S7) Drying, dry the comparative sample at 60℃.

[0084] After testing, the purity of the lapis lazuli pigment prepared in this comparative example is only 75%, the blueness value b* is -35.6, and the calcite residue is as high as 8.3%. Static solidification under 60% humidity results in a microcrack density of 0, an alkali water penetration rate of only 0.1mm / min, and calcite cannot be effectively dissolved. Single-temperature ultrasonic (25℃) further causes 8.3% wax residue, blocking the pores of the pigment. The data show that humidity control and kneading and pressing are necessary conditions for purification.

[0085] Comparative Example 2

[0086] A method for purifying lapis lazuli according to the present comparative example, comprising the following steps,

[0087] (S1) Material weighing, take 400g of lapis lazuli powder, 100g of bleached beeswax with a saponification value of 95mgKOH / g, 100g of mastic resin with an acid value of 4mgKOH / g, and 200g of dust-free pine resin;

[0088] (S2) Melt mixing, place the beeswax, resin, and pine resin in a porcelain bowl and melt at 83℃±1℃ for 30 minutes. After stirring to a liquid state, add the lapis lazuli powder and continue stirring to form a uniform slurry;

[0089] (S3) Direct forming, skip the filtering step, and pour the slurry directly onto a non-stick plate to cool and roll;

[0090] (S4) Air drying and curing, place the formed material in a 35% humidity ventilated environment and manually knead 3 times a day for 6 days to form microcracks;

[0091] (S5) Alkaline purification, immerse the air-dried material in 42℃ warm alkaline water containing 0.8wt% sodium carbonate, and knead for 60 minutes after applying linseed oil with both hands. Replace the alkaline water every 20 minutes;

[0092] (S6) Delipidation refining, after purification, transfer the material to boiling water and boil for 5 minutes, then put it into a 40kHz ultrasonic cleaning machine and follow the 25℃ / 2min→40℃ / 5min→55℃ / 3min step program for cleaning;

[0093] (S7) Drying, dry in a 60℃ oven until the moisture content is 1.8%, and obtain the purified lapis lazuli pigment.

[0094] After testing, the purity of the lapis lazuli pigment prepared in this example dropped to 70%, the blueness value b* decreased to -38.5, and the pyrite residue reached 0.8%. Without 200 mesh filtering, the proportion of >100μm agglomerates was 23%(including 5.2% pyrite), and the encapsulated iron sulfide released Fe 2+ , making the pigment color gray. The air-dried microcrack density reached 17 / mm 2 , but the impurities inside the agglomerates could not contact the alkaline solution, resulting in 4.5% calcite residue.

[0095] Example 3

[0096] A lapis lazuli purification preparation method of this example includes the following steps,

[0097] (S1) Material weighing, take 400g of lapis lazuli powder, 100g of bleached beeswax with a saponification value of 95mgKOH / g, 100g of mastic resin with an acid value of 4mgKOH / g, and 200g of dust-free pine resin;

[0098] (S2) melt mixing, melt the beeswax, resin, and turpentine in a porcelain bowl at 83℃±1℃ for 30 minutes, add the malachite powder after stirring to liquid state, and continue stirring to form a uniform slurry;

[0099] (S3) filtration and molding, filter the slurry through a 200-mesh stainless steel screen to remove >75μm agglomerates, then pour it onto a non-stick plate and cool to room temperature to solidify, roll it into a 2cm diameter strip and cut it into 10cm segments;

[0100] (S4) air drying and curing, place the segments in a 35% humidity environment and manually knead them 3 times a day for 6 days to form microcracks;

[0101] (S5) purification with alkaline water, immerse the dried segments in 42℃ warm alkaline water containing 0.8wt% sodium carbonate, and knead them for 60 minutes with hands coated with linseed oil, replacing the alkaline water every 20 minutes;

[0102] (S6) dewaxing and refining, after purification, transfer the segments to boiling water and boil them for 5 minutes, then put them into a 40kHz ultrasonic cleaner and follow the program 25℃ / 2min→40℃ / 5min→55℃ / 3min;

[0103] (S7) drying, dry the segments in a 60℃ oven until the moisture content is 1.8%, and obtain the purified malachite pigment.

[0104] The purity of the malachite pigment prepared in the comparative example is only 72%, the blue value b* is as low as -34.1, and the calcite residue is as high as 4.1%. The ratio mismatch (beeswax:resin=1:0.5) results in a wrapping coverage of only 54%, and the lack of resin causes the exposure of calcite; the excess beeswax forms a wax layer with uneven thickness, and after stepwise ultrasonic cleaning, there are still 12% of wax residues, and after alkaline washing, the pigment agglomeration rate increases, and the yield of 350-mesh fine particles is insufficient.

[0105] The melting mixing, daily kneading to form microcracks, and stepwise ultrasonic cleaning in Example 1 achieve a purity of up to 88% and a deep blue tone of b* value -42.5, with a color saturation improvement of 32%; the omission of the kneading step in Comparative Example 1 results in a purity of 75% and a calcite residue of up to 8.3%, the cancellation of 200-mesh filtration in Comparative Example 2 increases the pyrite residue to 0.8%, and the ratio mismatch in Comparative Example 3 causes insufficient wrapping and 12% of wax residues. The present invention creatively combines material ratio (4:1:1:2), humidity control (≤40%), and mechanical kneading to induce microcracks, efficiently removes impurities, and at the same time, avoids the use of strong acid throughout the process, the alkaline water can be recycled, energy consumption is reduced by 40%, and Example 4 verifies the feasibility of industrialization, with a batch purity deviation of less than 0.5%, providing a reliable high-quality pigment for traditional mural art.

Claims

1. A method for high purity purification of lapis lazuli pigments, characterized by: The method comprises the following steps, (S1) material weighing, accurately weighing malachite powder, beeswax, resin, and pine resin according to a mass ratio of 4:1:1:2; (S2) melting and mixing, heating the beeswax, resin, and pine resin to 80-85℃ to melt into a liquid state, and then adding the malachite powder after stirring, and continuously stirring until a uniform slurry is formed; (S3) filtering and forming, pouring the slurry on a non-stick plate after filtering, cooling to room temperature to solidify, rubbing into a long strip and segmenting; (S4) air drying and solidifying, naturally air drying the segmented material in a ventilated environment for 5-7 days, and turning over and rubbing every day; (S5) alkali water purification, rubbing the air-dried material in warm alkali water at 40-45℃ for 60 minutes, the alkali water being a water solution containing 0.5-1wt% sodium carbonate, and replacing the alkali water every 20 minutes; (S6) dewaxing and refining, removing the wax from the purified material by boiling in boiling water for 5 minutes, and then cleaning by ultrasonic waves at 40kHz for 10 minutes; (S7) drying, drying at 60℃ to a water content of ≤2%, to obtain the purified malachite pigment.

2. The method for preparing high purity emerald pigment according to claim 1, characterized in that: The heating temperature in the step (S2) is strictly controlled at 80-85℃, and the resin is not fully dissolved when the temperature is lower than 80℃, and the pine resin is carbonized when the temperature is higher than 85℃.

3. The method for preparing high purity emerald pigment according to claim 1, characterized in that: The filtering in the step (S3) uses a 200-mesh stainless steel screen to intercept undispersed mineral agglomerates.

4. The method for preparing high purity emerald pigment according to claim 1, characterized in that: The air drying environment in the step (S4) has a humidity of ≤40%, and the material is rubbed 3 times a day to promote the formation of internal microcracks, which is beneficial to the subsequent penetration of alkali water.

5. The method for preparing high purity emerald pigment according to claim 1, characterized in that: The rubbing operation in the step (S5) uses linseed oil to reduce the adsorption loss on the surface of the material.

6. The method for preparing high purity emerald pigment according to claim 1, characterized in that: The ultrasonic cleaning in the step (S6) uses a stepwise temperature program, first cleaning at 25℃ for 2 minutes, then cleaning at 40℃ for 5 minutes, and finally cleaning at 55℃ for 3 minutes.

7. The method for preparing high purity emerald pigment according to claim 1, characterized in that: The resin is a natural resin with an acid value of ≤5mgKOH / g, selected from mastic resin, frankincense, or a combination thereof.

8. The method for preparing high purity emerald pigment according to claim 1, characterized in that: The beeswax is bleached beeswax with a saponification value of 85-100mgKOH / g.

9. The method for preparing high purity emerald pigment according to claim 1, characterized in that: The malachite powder is a pretreated powder with iron removed by magnetic separation, residual iron content ≤0.3%, and carbonates removed by pickling, with residual carbonates ≤1%.

10. The method for preparing high purity emerald pigment according to claim 1, characterized in that: The final product meets the following indicators: particle size of ≥95% above 350 mesh; CIE b* value ≤-40 under D65 light source; and non-malachite mineral impurity content ≤2%.

Images