A method for improving the whiteness of black talcum powder and its product

Abstract

The present invention provides a method for improving the whiteness of black talc powder and a product thereof, relating to the field of non-metallic mineral processing technology. Specifically, the method comprises the following steps: 1) wet ultrafine grinding the black talc powder to obtain a slurry; 2) adjusting the solid content of the slurry obtained in step 1), adding a flocculant, stirring, and then allowing to stand and separate; 3) removing the upper slurry from the layered slurry in step 2), adding an oxidant thereto, and allowing to stand; 4) filtering the talc slurry treated in step 3), washing, and drying to obtain the whitened black talc powder. The present invention utilizes an ultrafine grinding method to separate most of the carbon in the black talc from the talc, then utilizes a flocculant to flocculate the carbon particles, causing the unflocculated talc to suspend in the middle and upper portions of the slurry. Finally, the middle and upper portions of the slurry are treated with an oxidant to obtain talc with high whiteness. The overall whitening method is simple, efficient, low in energy consumption, safe, and environmentally friendly, making it particularly suitable for large-scale industrial production.

Description

Technical Field

[0001] The invention belongs to the technical field of non-metallic mineral processing, and particularly relates to a method for improving the whiteness of black talcum powder and a product thereof. Background Art

[0002] Due to its unique physical and chemical properties and lamellar structure, talc is widely used in ceramics, chemicals, metallurgy, papermaking, plastics, coatings, medicine, cosmetics, and sculpture. Talc's crystal structure allows it to be processed into fine flaky particles. These particles have a large specific surface area and good dispersibility. They are thermally non-conductive and have excellent electrical insulation properties. Talc porcelain made from high-quality talc is a high-end insulating product. The high aspect ratio of flaky talc also offers excellent adsorption and covering power. Combined with its excellent chemical stability, talc is suitable as a coating raw material, improving the coating's fire resistance and weathering resistance.

[0003] Whiteness is a key technical indicator that influences the application of talc. White talc can be widely used in the production of rubber, plastics, coatings, putty, and other products. Furthermore, if you want to produce white or colored products, you must use white talc.

[0004] Black talc is a general term for black and grayish-black talc. Its black color is primarily due to its carbon content. The primary mineral in black talc is talc, along with some quartz and carbon. my country has abundant black talc resources, but its low whiteness limits its widespread application, limiting it to industries such as ceramics and rubber. Consequently, the whiteness issue has become a bottleneck hindering the development of the black talc industry.

[0005] According to statistics, Jiangxi Guangfeng is the world's largest and highest-grade "black talc capital". The silicon and magnesium contents of Guangfeng black talc can reach about 60% and 30% respectively, making it a rare high-grade black talc mine at home and abroad. After reasonable grinding and calcination at an appropriate temperature, the whiteness of Guangfeng black talc can reach 96.5%. The properties of the calcined enstatite are stable, which provides a way for the application of black talc. It is a superior masterbatch to replace kaolin in the manufacture of high-end daily-use ceramics, building ceramics, craft ceramics and industrial ceramics, and the price is very cost-effective compared to kaolin. However, the calcination method in the existing technology requires high energy consumption, and after calcination, it is no longer talc. The enstatite produced can only be used in the ceramic field, which limits the application field of black talc after whitening.

[0006] Therefore, it is a technical problem that needs to be solved urgently by those skilled in the art to provide a method for whitening black talc with low energy consumption, without changing the crystal structure of the talc and with high product whiteness, so that the product can be widely used in various talc application fields. Summary of the Invention

[0007] The present invention aims to provide a method for improving the whiteness of black talc powder, addressing the prior art issue of low whiteness due to the high carbon content in Jiangxi Guangfeng black talc. The present invention utilizes ultrafine grinding to separate the majority of carbon particles from the talc particles. This method then utilizes a flocculant for selective flocculation. Explorative research has shown that the addition of a flocculant causes the carbon particles to sink to the bottom of the slurry, while the unflocculated talc remains suspended in the upper middle portion, where the carbon content is less than 1%. This upper middle portion is then treated with an oxidant to produce high-whiteness talc. This overall whitening method is simple, efficient, energy-efficient, safe, and environmentally friendly, making it particularly suitable for large-scale industrial production.

[0008] To achieve the above object, the present invention provides a method for improving the whiteness of black talcum powder, comprising the following steps:

[0009] 1) wet ultrafine grinding black talc to obtain a slurry;

[0010] 2) adjusting the solid content of the slurry obtained in step 1), adding a flocculant, stirring, and then allowing to stand and separate;

[0011] 3) In the layered slurry of step 2), take out the upper layer slurry, add an oxidant thereto, and let it stand;

[0012] 4) filtering the talc slurry treated in step 3), washing, and drying to obtain whitened black talc powder.

[0013] In a preferred embodiment, in step 1), the chemical composition and content of the black talc powder are: talc>85%, dolomite and quartz stone total content<10%, carbon 1-5%.

[0014] In a preferred embodiment, in step 1), the wet ultrafine grinding method is: using black talc as raw material, using ball milling media and adding appropriate amount of water for ball milling, wherein the ball milling media comprises one of zirconia ceramic beads, diamond or alumina ceramic beads, and the ball milling media size is The filling rate of the grinding media in the grinding chamber is 65-80%

[0015] In a preferred embodiment, in step 1), the particle size of the slurry after wet ultrafine grinding is 800-4000 mesh.

[0016] In a preferred embodiment, in step 2), the solid content of the slurry after adjustment is 5-30%.

[0017] In a preferred embodiment, in step 2), the flocculant is one or more of polyaluminum chloride, polyferric chloride or polyacrylamide.

[0018] In a preferred embodiment, in step 2), the mass ratio of the flocculant to black talc is (0.1-1.0):100.

[0019] In a preferred embodiment, in step 3), the oxidant is one or more of sodium hypochlorite, hydrogen peroxide and ozone.

[0020] In a preferred embodiment, in step 3), the mass ratio of the oxidant to black talc is (1-15):100.

[0021] Another object of the present invention is to provide a white high-grade talc product prepared by any one of the above methods.

[0022] Compared with the prior art, the technical solution of the present invention has the following advantages:

[0023] 1. The present invention effectively removes carbon impurities from black talc through ultrafine grinding, flocculation sedimentation, and oxidation. This eliminates the need for high-temperature calcination, a process that is energy-efficient, environmentally friendly, safe, and efficient. It can continuously produce large quantities of high-whiteness, low-cost talc products, significantly reducing costs and increasing efficiency.

[0024] 2. Because the method of the present invention does not use the traditional calcination process, it does not cause the talc mineral structure to undergo phase changes and does not transform into enstatite. Therefore, it can effectively expand the application field of black talc whitening products and be widely used in the preparation of plastics, rubber, coatings and other materials.

[0025] 3. The present method can fully utilize the black talc ore produced in Guangfeng District, Shangrao City, Jiangxi Province. After purification and whitening treatment according to the present invention, one ton of raw black talc ore can produce 700-800 kilograms of white talc powder with a whiteness of over 86% and 200-300 kilograms of carbon-rich ore powder. The carbon-rich ore powder, enriched with carbon, can be further processed or sold as a byproduct, expanding the resource utilization of black talc ore and improving economic benefits. DETAILED DESCRIPTION

[0026] In order to enable those skilled in the art to better understand the present invention, the present invention is further described in detail below in conjunction with specific embodiments. However, it should be understood that the protection scope of the present invention is not limited by the specific embodiments.

[0027] The embodiments of the present invention provide a method for improving the whiteness of black talc powder and a product thereof, thereby solving the technical problems of high energy consumption and high cost in the prior art of calcining and whitening black talc.

[0028] The technical solution of this application is described in detail below through specific embodiments:

[0029] The present invention provides a method for improving the whiteness of black talcum powder, which specifically comprises the following steps:

[0030] 1) wet ultrafine grinding black talc to obtain a slurry;

[0031] 2) adjusting the solid content of the slurry obtained in step 1), adding a flocculant, stirring, and then allowing to stand and separate;

[0032] 3) In the layered slurry of step 2), take out the upper layer slurry, add an oxidant thereto, and let it stand;

[0033] 4) filtering the talc slurry treated in step 3), washing, and drying to obtain whitened black talc powder.

[0034] In a preferred embodiment, in step 1), the chemical composition and content of the black talc powder are: talc>85%, dolomite and quartz stone total content<10%, carbon 1-5%.

[0035] In a preferred embodiment, in step 1), the wet ultrafine grinding method is: using black talc as raw material, using ball milling media and adding appropriate amount of water for ball milling, wherein the ball milling media comprises one of zirconia ceramic beads, diamond or alumina ceramic beads, and the ball milling media size is The filling rate of the grinding medium in the grinding chamber is 65-80%; more preferably, the size of the grinding medium is Filling rate 70-80%.

[0036] In a preferred embodiment, in step 1), the particle size of the slurry after wet ultrafine grinding is 800-4000 mesh, preferably 1250-4000 mesh. In the present invention, by controlling the parameters of the wet grinding method, a slurry with an ultrafine particle size is obtained, so that most of the carbon in the black talc is separated from the talc, facilitating subsequent removal.

[0037] In a preferred embodiment, in step 2), the solid content of the slurry after adjustment with water is 5-30%, preferably, the solid content of the slurry after adjustment is 10-15%.

[0038] In a preferred embodiment, in step 2), the flocculant is one or more of polyaluminum chloride, polyferric chloride or polyacrylamide.

[0039] In a preferred embodiment, in step 2), the mass ratio of the flocculant to the black talc is (0.1-1.0):100. Preferably, the mass ratio of the flocculant to the black talc is (0.3-0.6):100.

[0040] The flocculant selected in the present invention is cheap, easy to purchase, and can achieve the effect of flocculating carbon elements with a relatively small amount. In terms of the amount of flocculant used, if it exceeds the above range, it will cause resource waste and reduce the yield of high-whiteness talc.

[0041] In a preferred embodiment, in step 2), the stirring condition is: stirring at 100-2000 rpm for 5-40 min, preferably, the stirring condition is 300-1200 rpm; and the standing time is 10-20 min.

[0042] In the present invention, a flocculant is added to a black talc slurry with an ultrafine particle size and then stirred sufficiently to cause the free carbon particles in the black talc to flocculate. After standing, the carbon particles sink to the bottom of the slurry, while the lighter talc that has not been flocculated will be suspended in the upper part of the slurry, thereby preliminarily separating the two.

[0043] In a preferred embodiment, in step 2), the middle and lower layers of slurry after stratification are collected, filtered, washed, and dried to obtain carbon-rich ore powder. Detection shows that the carbon content of the carbon-rich ore powder is about 20%, which can be further processed or sold as a carbon raw material.

[0044] In a preferred embodiment, in step 3), the oxidant is one or more of sodium hypochlorite, hydrogen peroxide and ozone, wherein ozone includes one of gaseous ozone and liquid ozone.

[0045] In a preferred embodiment, in step 3), the mass ratio of the oxidant to black talc is (1-15):100.

[0046] In the present invention, adding an oxidant to the preliminarily separated black talc particles further reduces the carbon content in the talc. Furthermore, the reaction product produced by the selected oxidant is colorless, exhibiting a significant whitening and carbon removal effect. Furthermore, after flocculation and separation, the carbon content in the upper layer of liquid is less than 1%. Only a small amount of oxidant is required to oxidize the carbon element, saving reagent usage and reducing production costs.

[0047] In a preferred embodiment, in step 3), the oxidant is liquid ozone water, and the mass ratio of the liquid ozone water to black talc is (3-8):100.

[0048] In a preferred embodiment, in step 3), the oxidation reaction time is 4-200 hours.

[0049] In a preferred embodiment, in step 4), the filtration, washing, and drying can be performed using conventional methods known to those skilled in the art, as long as the desired operation is achieved. Preferably, the washing step involves rinsing the mixture 2-4 times with deionized water to remove surface oxidants, and the drying step involves drying at 60-150°C for 2-4 hours.

[0050] Another object of the present invention is to provide a white high-grade talc product prepared by any one of the above methods.

[0051] Unless otherwise specified, the technical means used in the present invention are conventional means well known to those skilled in the art. The various raw materials, reagents, instruments, and equipment used in the present invention can be purchased from the market or prepared by existing methods. Unless otherwise specified, the reagents used in the present invention are of analytical grade.

[0052] The black talc used in the examples of the present invention is produced in Guangfeng District, Shangrao City, Jiangxi Province. The black talc contains more than 85% talc, less than 10% dolomite and quartz stone in total, 1-5% carbon, and 6.78% whiteness.

[0053] The whiteness test method described in the embodiment of the present invention is the "Whiteness Measurement Method of Building Materials and Non-metallic Mineral Products (GB / T 5950-2008)".

[0054] Example 1

[0055] A method for whitening black talc comprises the following steps:

[0056] 1. Wet-grind black talc powder to 1000 mesh to obtain a slurry;

[0057] 2. Adjust the solid content of the slurry in step 1) to 5%, add 0.1% of the mass of black talc as polyaluminum chloride flocculant, stir for 10 minutes and then let it stand to allow the carbon particles in the black talc to flocculate and sink to the bottom of the slurry;

[0058] 3. Take out the upper layer of the slurry separated from the upper and lower layers in step 2), add sodium hypochlorite oxidant with a mass ratio of 3% of black talc powder to carry out oxidation and carbon removal treatment for 24 hours;

[0059] 4. Take out the slurry after oxidation in step 3), filter, wash and dry it to obtain the whitened talc powder.

[0060] After testing, the whiteness of the black talc after whitening in this embodiment is 86%.

[0061] Example 2

[0062] A method for whitening black talc comprises the following steps:

[0063] 1. Wet-grind black talc powder to 4000 mesh to obtain a slurry;

[0064] 2. Adjust the solid content of the slurry in step 1) to 30%, add 1.0% polyacrylamide flocculant by weight of black talc powder, stir for 30 minutes and then let it stand to allow the carbon particles in the black talc powder to flocculate and sink to the bottom of the slurry;

[0065] 3. Take out the upper layer of the slurry separated from the upper and lower layers in step 2), add ozone water oxidant with a weight ratio of 15% of black talc powder to carry out oxidation and carbon removal treatment for 150 hours;

[0066] 4. Take out the slurry after oxidation in step 3), filter, wash and dry it to obtain the whitened talc powder.

[0067] After testing, the whiteness of the black talc after whitening in this embodiment is 91%.

[0068] Example 3

[0069] A method for whitening black talc comprises the following steps:

[0070] 1. Wet-grind black talc powder to 2500 mesh to obtain a slurry;

[0071] 2. Adjust the solid content of the slurry in step 1) to 10%, add 0.5% of the mass of black talc powder as polyferric chloride flocculant, stir for 20 minutes and then let it stand to allow the carbon particles in the black talc powder to flocculate and sink to the bottom of the slurry;

[0072] 3. Take out the upper layer of the slurry separated from the upper and lower layers in step 2), add hydrogen peroxide with a concentration of 5% by weight of black talc powder, and perform oxidation and carbon removal treatment for 130 hours;

[0073] 4. Take out the slurry after oxidation in step 3), filter, wash and dry it to obtain the whitened talc powder.

[0074] After testing, the whiteness of the black talc after whitening in this embodiment is 89%.

[0075] The foregoing descriptions of specific exemplary embodiments of the present invention are for purposes of illustration and description. These descriptions are not intended to limit the invention to the precise forms disclosed, and it is apparent that many variations and modifications are possible in light of the foregoing teachings. The exemplary embodiments have been selected and described for the purpose of explaining the specific principles of the invention and their practical application, thereby enabling those skilled in the art to realize and utilize a variety of exemplary embodiments of the invention and various options and modifications. The scope of the invention is intended to be defined by the claims and their equivalents.

Claims

1. A method for improving the whiteness of black talcum powder, characterized in that: The following steps are involved: 1) Wet ultrafine grinding of black talc powder to obtain a slurry; 2) adjusting the solid content of the slurry obtained in step 1), adding a flocculant, stirring, and then allowing to stand and separate; 3) In the layered slurry of step 2), take out the upper layer slurry, add an oxidant thereto, and let it stand; 4) filtering, washing, and drying the talc slurry treated in step 3) to obtain whitened black talc powder; In step 1), the chemical composition and content of the black talc powder are: talc>85%, dolomite and quartz stone total content<10%, carbon 1-5%, whiteness 6.78%; In step 1), the wet ultrafine grinding method comprises: using black talc as raw material, using ball milling media and adding an appropriate amount of water for ball milling, wherein the ball milling media comprises one of zirconia ceramic beads, diamond or alumina ceramic beads, the ball milling media has a size of φ0.08-1.5 mm, and the filling rate of the ball milling media in the grinding chamber is 65-80%; In step 2), the flocculant is one or more of polyaluminum chloride, polyferric chloride or polyacrylamide; the mass ratio of the flocculant to black talc (0.1-1.0) is 100; In step 3), the oxidant is one or more of sodium hypochlorite, hydrogen peroxide and ozone; the mass ratio of the oxidant to black talc is (1-15): 100; After being purified and whitened by this method, one ton of black talc ore can produce 700-800 kg of white talc powder with a whiteness of more than 86% and 200-300 kg of carbon-rich ore powder.

2. The method for improving the whiteness of black talcum powder as claimed in claim 1, wherein In step 1), the particle size of the slurry after wet ultrafine grinding is 800-4000 mesh.

3. The method for improving the whiteness of black talcum powder as claimed in claim 1, wherein In step 2), the solid content of the slurry is adjusted to 5-30%.