43results about How to "High whiteness" patented technology

The present disclosure relates to a lyocell material with controlled whiteness by hydrogen peroxide treatment and a manufacturing method thereof, wherein the lyocell material has improved whiteness due to an aging effect through drying and packaging by a predetermined amount of hydrogen peroxide remaining in a tow, and may replace a CA cigarette filter to lower environmental pollution problems caused by discarded cigarette butts, and thus the lyocell material is suitable as a cigarette filter.

The application provides a continuous production method and system of calcium hydroxide with high whiteness and high specific surface area, and relates to the technical field of limestone deep processing. The continuous production method comprises the following steps: step one: continuously adding quicklime particles into the inlet of a primary digester, continuously adding digestion water and an additive into the inlet of the primary digester, and carrying out premixing and pre-digestion under stirring conditions; step two: continuously introducing the discharge of the primary digester into a secondary digester, continuously adding digestion water and an additive into the inlet of the secondary digester, and stirring and digesting and aging; step three: the discharge of the secondary digester is sequentially introduced into a tertiary digester, a quaternary digester and a quinary digester for digestion and aging, and the product is obtained after grading by a grader. The method can continuously prepare calcium hydroxide with high whiteness and high specific surface area, and has the characteristics of simple process, short time consumption, remarkable effect and low energy consumption, and has been applied in actual production and has good use effect.

The invention relates to a full-particle-size flotation process method for improving the recovery rate of lepidolite through fine silt pretreatment. The full-particle-size flotation process method comprises the following steps that crushed lepidolite raw ore is subjected to ore grinding operation; conveying the ore grinding product to a first hydrocyclone; feeding an underflow product of the first hydrocyclone into a five-lamination high-frequency vibrating screen, returning an oversize product to a ball mill for regrinding, and removing iron from an undersize product; feeding the non-magnetic material subjected to iron removal into a spreading chute; carrying out shaking table roughing and re-selection on the distributed ore concentrate; feeding the cloth sliding tailings and the shaking table roughing and checking tailings into a first-section cyclone; overflow of the first-section cyclone is fed into a first deep-cone thickener; the deep cone underflow is added into a fine silt pretreatment tank, a dispersing agent is added into the fine silt pretreatment tank, uniform stirring and pretreatment are performed, and pretreated fine silt is obtained; and the first-section cyclone underflow and pretreated fine silt mixed ore pulp is added into a flotation stirring barrel, a matched collecting agent is added, and flotation operation is carried out. The method can improve the recovery rate of lepidolite, synchronously improve the whiteness of feldspar and the like.

This invention discloses a hydrophilic organosilicon finishing agent and its preparation method, belonging to the field of textile auxiliaries technology. The finishing agent is prepared by compounding polyurethane-modified silicone oil and amide-modified polyether silicone oil at a mass ratio of 1:1~2, followed by emulsification with an emulsifier. The polyurethane-modified silicone oil is obtained by polymerizing a blocked polyurethane prepolymer with terminal epoxy polyether silicone oil and block silicone oil; the amide-modified polyether silicone oil is obtained by amidation reaction of terminal epoxy polyether silicone oil and polyether amine in the presence of organic acid. This invention, through the synergistic effect of the two-component compound, provides skeletal support and elastic recovery through polyurethane segments and a hydrophilic surface layer through amide groups, effectively solving the problem of balancing hand feel and hydrophilicity in nylon-spandex fabrics. The finished fabric hand feel rating can reach level 4 or higher, water droplet diffusion time can be as low as 0.9s, the emulsion has good stability, and it is not prone to oil drift, significantly superior to similar products on the market.

The invention discloses a desulfurization ash resource utilization process which comprises the following steps: performing magnetic separation on desulfurization ash, and mixing with water to obtain first desulfurization ash slurry; adding a mixed solution of sodium acetate and hydrochloric acid, reacting to obtain second desulfurized fly ash slurry with acidic pH, and collecting CO2 generated in the reaction process; introducing air to oxidize the second desulfurized fly ash slurry at the temperature of 60-80 DEG C, and stirring to react to obtain third desulfurized fly ash slurry; performing solid-liquid separation on the third desulfurized fly ash slurry to obtain solid calcium sulfate and a mixed solution of calcium acetate and sodium chloride; adding sodium carbonate into the mixed solution of calcium acetate and sodium chloride, and performing solid-liquid separation after reaction to obtain solid calcium carbonate and the mixed solution of calcium acetate and sodium chloride; a mixed solution of calcium acetate and sodium chloride is collected and circularly used for preparing the first desulfurized fly ash slurry. According to the method, the resource utilization process of the desulfurized fly ash is optimized, generation of harmful gases such as sulfur dioxide and ammonia gas is avoided, and valuable calcium sulfate and calcium carbonate products are obtained.

This invention relates to a method for desiliconizing green liquor in papermaking, belonging to the field of papermaking pulping chemical regeneration technology. This method aims to solve the technical problem in existing technologies where direct carbon dioxide is introduced into green liquor for desiliconization, resulting in the formation of colloids from the generated silicic acid, making subsequent solid-liquid separation difficult. The key points of the technical solution are: first, solid-liquid separation of the green liquor is performed to obtain a clear green liquor; then, white mud slurry is added to the clear liquor as seed crystals, and carbon dioxide gas is introduced to carry out a carbonization reaction, generating an easily separable silicon-containing suspension; next, solid-liquid separation is performed on the silicon-containing suspension to obtain a silicon-containing filter cake and a causticizing mother liquor; finally, calcium hydroxide is added to the causticizing mother liquor to carry out a causticizing reaction, obtaining white liquor and recyclable white mud slurry. This method is mainly applied to the desiliconization and purification of green liquor during the alkali recovery process in papermaking, and can utilize carbon dioxide in industrial flue gas to achieve carbon resource utilization; the separated silicon-containing filter cake can be further processed into activated calcium silicate products.

The invention discloses an art glaze based on ceramic waste and a preparation method thereof, and relates to the technical field of ceramic glazes, the art glaze is prepared from the following components by weight: 30-50 parts of frit, 5-15 parts of quartz, 10-20 parts of calcite, 3-6 parts of burnt zinc, 6-10 parts of titanium dioxide, 25-35 parts of barium carbonate, 10-25 parts of modified ceramic powder, 2-4 parts of iron oxide red, and 3-6 parts of talc. According to the invention, high-valued recycling of the ceramic waste is realized, waste is turned into wealth, the production cost and environmental load are remarkably reduced, and the obtained art glaze is flat and bright in glaze surface, unsophisticated and elegant in color and lustre, warm and moist in texture like jade, and excellent in thermal shock resistance and weather resistance. According to the technology, the problems that a traditional glaze layer is prone to cracking and pinhole defects are effectively solved, double improvement of environmental protection benefits and product quality is achieved, and the technology has extremely high market popularization value.

The invention belongs to the technical field of organic compounds and artificial boards, and relates to a whitening agent, a preparation method thereof and application of the whitening agent in whitening type medium density fiberboards, the whitening agent comprises the following components by mass percent: 2-5% of hydrogen peroxide, 0.2-0.6% of sodium silicate, 0.5-1.5% of sodium hydroxide, 0.1-0.4% of water-soluble stilbene fluorescent whitening agent and the balance of water. The preparation method comprises the following steps: sequentially adding the components into water at 60-65 DEG C, stirring and dissolving, and keeping the temperature at 60 DEG C for later use. When being applied, the cleaning agent is added in a wood chip washing process, the mass of the cleaning agent is 1-1.5% of the total mass of cleaning water for the first time, and 0.05-0.08% of the cleaning agent is supplemented per hour subsequently. According to the whitening agent, through the synergistic effect of chemical oxidation and physical color complementing, the whiteness of a fiberboard reaches 31-36 (only 14 in a conventional process), the physical and chemical properties meet the GB / T 11718-2021 standard, and the whitening agent is environmentally friendly, free of residues, simple to prepare and apply, suitable for industrial continuous production and capable of remarkably improving the added value of products.

The application relates to the technical field of medical textile materials, and discloses an antibacterial and breathable medical gauze sheet, which comprises a base material and an antibacterial functional layer loaded on the base material, and the functional layer is formed by chemical reaction of carboxymethyl chitosan, tannic acid, boric acid, citric acid and zinc ions. Through boric acid complexation and citric acid competitive coordination, a double interpenetrating network structure of covalent bonds and coordination bonds is formed inside and outside the gauze fibers. The structure effectively inhibits the oxidative browning of tannic acid and eliminates the difference in the skin-core distribution of the functional components. The obtained gauze sheet is not only high in whiteness and good in breathability, but also has excellent washing fastness and long-acting and broad-spectrum antibacterial performance.

The present application relates to a kind of polybutylene terephthalate resin composition and its preparation method and application, the polybutylene terephthalate resin composition includes biobased polybutylene terephthalate resin, titanium element, phosphorus element and cobalt element;The weight content of titanium element in the polybutylene terephthalate resin composition is 20-150ppm, the weight content of phosphorus element is 2-50ppm, the weight content of cobalt element is 4-100ppm;The mass ratio of titanium element, phosphorus element and cobalt element in the polybutylene terephthalate resin composition is (2-20):(1-2):(1-10).The polybutylene terephthalate resin composition provided by the present application, by controlling the weight content and mass ratio of titanium element, phosphorus element and cobalt element within suitable range, can make polybutylene terephthalate resin composition have high whiteness, excellent mechanical properties and aging resistance.

The invention provides a whitening type composite modifier as well as a preparation method and application thereof, and belongs to the technical field of inorganic material modification. The whitening type composite modifier provided by the invention is prepared from the following preparation raw materials in parts by mass: 55 to 65 parts of titanium dioxide, 2 to 5 parts of a fluorescent whitening agent, 15 to 25 parts of an aluminate coupling agent, 5 to 10 parts of a titanate coupling agent, 10 to 20 parts of stearic acid, 2 to 5 parts of a dispersing agent and 1 to 2 parts of an antioxidant. The whitening type composite modifier can be applied to modification of various inorganic powder, the whiteness of the inorganic powder treated by the whitening type composite modifier is obviously improved, and the dispersity and the stability are obviously improved.

This invention discloses an adenine-based heat stabilizer and its application in PVC composites, belonging to the field of heat stabilizer technology. The heat stabilizer is an adenine-based substance or a compound of an adenine-based substance and an auxiliary stabilizer. The adenine-based substance is adenine or adenine nucleoside, and the auxiliary stabilizer is at least one of calcium salt stabilizers, zinc salt stabilizers, and polyol stabilizers. This adenine-based heat stabilizer can improve the initial whiteness of PVC and impart better long-term stability to PVC. Its application in PVC composites can effectively improve the thermal stability and mechanical properties of PVC composites, possessing practical application value.

This invention belongs to the field of resin preparation technology, specifically relating to a polyphenylene sulfide resin and its preparation method. The preparation method includes the following steps: a composite stabilizer, anhydrous sodium sulfide, and a polar solvent are first mixed; the resulting first mixture undergoes a dehydration reaction to obtain a dehydrated reaction solution; the dehydrated reaction solution is then mixed with p-dichlorobenzene; the resulting second mixture undergoes prepolymerization and postpolymerization sequentially to obtain the polyphenylene sulfide resin; the composite stabilizer includes carbodiimide having the structure of formula I, lithium chloride, and sodium hydroxide; R 1 -(N=C=N) n -R 2 Equation I; n is an integer from 1 to 20; R 1 and R 2 The polymer is independently selected from substituted or unsubstituted alkyl, cycloalkyl, aryl, or aralkyl groups. The composite stabilizer in this invention effectively inhibits excessive hydrolysis by polar solvents, improves reaction efficiency, and controls the polymer molecular structure, thereby obtaining high molecular weight, high yield, and high whiteness PPS resin.

This application relates to the technical field of textile printing and dyeing, specifically disclosing a continuous flat-width pretreatment bleaching and washing process for knitted fabrics. The continuous flat-width pretreatment bleaching and washing process for knitted fabrics includes the following steps: pre-wetting: pre-wetting the knitted fabric with a pre-wetting solution to obtain a wetted knitted fabric; vacuum impregnation bleaching: vacuum impregnating and bleaching the wetted knitted fabric with a bleaching solution to obtain a bleached knitted fabric; steaming reaction: sending the bleached knitted fabric into a steaming chamber for a steaming reaction to obtain a steamed knitted fabric; washing: adding the steamed knitted fabric to a washing tank for washing, followed by neutralization treatment to obtain a washed knitted fabric; cooling and setting: cooling and setting the width of the washed knitted fabric to obtain the pretreated bleached knitted fabric.

This invention discloses a method for preparing cubic nano-calcium carbonate based on monosaccharide regulation. Using monosaccharides as crystal guiding agents, the resulting cubic nano-calcium carbonate exhibits a cubic structure with an average particle size of 81-115 nm. The monosaccharide is either glucose or fructose. The preparation method includes the following steps: 1. Preparation of calcium oxide; 2. Preparation of monosaccharide-nano-calcium carbonate. The amount of monosaccharide added is 0.8-1.2 wt.% of the calcium oxide mass; the calcium oxide yield is 65-75%. The resulting nano-calcium carbonate has a whiteness value of 90.6-97.3 wb and an oil absorption value of 65.3-89.6 g DOP / 100 g CaCO3.

The invention provides a preparation method and application of high-dispersity food-grade titanium dioxide, and relates to the technical field of food additives. The preparation method comprises the following steps: S1, mixing a titanium dioxide crude product with concentrated sulfuric acid and deionized water, carrying out acid pickling, stirring for 20-40 minutes, adding deionized water, carrying out water washing, and carrying out filter pressing until filtrate is neutral, so as to obtain a filter cake; s2, filtering the filter cake through a sieve shaker, sanding, adding deionized water to dilute and wash until the conductivity of the slurry is stabilized below 400 [mu] S / cm, and grading to obtain slurry containing fine particles; s3, carrying out filter pressing on the slurry containing the fine particles, adding deionized water into an obtained filter cake, re-dispersing, and then carrying out spray drying and crushing to obtain food-grade titanium dioxide; the food-grade titanium dioxide obtained by the preparation method provided by the invention has excellent dispersity and long-term suspension stability, extremely high whiteness and extremely low color cast, the content of harmful heavy metals is reduced to an extremely low level, the particle size is controlled to be 0.3 mu m or below through fine processing steps of sanding, diluting and grading, the pore structure is larger than 50 nm, and the food-grade titanium dioxide has relatively good compactness and is suitable for industrial production. The agglomeration phenomenon is effectively reduced, and the method can be widely applied to food.

This invention provides a method for preparing and applying a trifluoromethoxyamide-bridged aromatic amine compound. The preparation method utilizes a continuous flow reaction system comprising two continuous flow reaction units connected in series, namely reaction unit A and reaction unit B. An amidation reaction is carried out in reaction unit A, and a reduction reaction is carried out in reaction unit B. The prepared trifluoromethoxyamide-bridged diamine compound exhibits high purity and whiteness and can be used to prepare polyimides for various electrical and optical components.

The application relates to the technical field of ceramics, and discloses a high-gloss high-whiteness ceramic glaze and a preparation method thereof.The high-gloss high-whiteness ceramic glaze comprises, in terms of weight fractions, 35-40 parts of calcite, 38-45 parts of wollastonite, 0.6-1.4 parts of potassium feldspar, 0.3-0.8 parts of calcined kaolin, 0.6-1.3 parts of clay, 1.2-2.8 parts of calcined zinc oxide, 4-16 parts of high-dispersibility zirconium silicate powder and the like; the phytic acid-based polyethylene glycol contains hydroxyl groups and a large number of sodium phosphate groups, can improve the interaction between polyethylene glycol molecular chains and the surface of zirconium silicate powder, effectively realizes surface modification and modification of the zirconium silicate powder, is favorable for overcoming the agglomeration of the zirconium silicate, and can be uniformly dispersed in a ceramic glaze matrix, and the gloss and whiteness of the glaze surface of the glaze are remarkably improved.

The present application relates to a phosphogypsum flotation impurity removal and whitening process, belonging to the technical field of solid waste treatment of phosphorus chemical industry, solves the problems of long process flow, complex operation, limited increase range of whiteness and purity of calcium sulfate dihydrate of the existing phosphogypsum impurity removal and whitening process. A phosphogypsum flotation impurity removal and whitening process, comprising the following steps: mixing phosphogypsum with water according to a certain mass percentage, and adding a certain amount of flotation reagent A; the ore pulp is stirred and scrubbed at high speed for a certain time; after scrubbing, the ore pulp is introduced into the flotation equipment for once reverse flotation; the underflow of reverse flotation is introduced into the stirring tank, and a certain amount of flotation reagent B is added; the ore pulp in the stirring tank is introduced into the flotation equipment for once again positive flotation, and the obtained foam product is obtained; the foam product is filtered and dewatered to obtain phosphogypsum concentrate. The process flow is short, the amount of flotation reagent is small, and the first-class product standard of GB / T23456-2018 "phosphogypsum" is met.

The invention provides a method for preparing nano calcium carbonate through amine cycle by capturing carbon dioxide through ferronickel slag, and belongs to the technical field of waste resource utilization and carbon dioxide capture and utilization. The method comprises the following steps: mixing ferronickel slag powder with an ammonium chloride solution, and performing leaching reaction to obtain a mixed solution; adding ammonium hydroxide into the mixed solution to adjust the pH value, and filtering to obtain a leaching solution; introducing the flue gas into an ammonia water absorption tower to prepare an ammonium bicarbonate solution; the ammonium bicarbonate solution and the leachate are subjected to a carbonization reaction, nano calcium carbonate is obtained, ammonia gas generated by the carbonization reaction is recycled to an absorption tower to be reused, and a closed amine circulation system is formed. According to the amine circulation method, efficient utilization of CaO in the ferronickel slag can be achieved, meanwhile, CO2 in the flue gas is captured, the purity of obtained nano calcium carbonate is larger than or equal to 93%, the whiteness is larger than or equal to 94%, the nano calcium carbonate has the advantages of being small in particle size, good in dispersity and high in additional value, and cooperative utilization of high-additional-value recycling of the ferronickel slag and carbon dioxide emission reduction is achieved.

The present application relates to coal gangue resource utilization field, specifically to a kind of coal gangue preparation calcined kaolin for glass fiber method, comprising: coal gangue is ground and homogenized, the obtained homogenized powder is made into concentration 30wt%-40wt% ore pulp, after magnetic separation impurity removal, add dilute acid leaching, then add complexing agent, solid-liquid separation, after drying the refined powder is calcined;Calcined powder is mixed with whitening agent, ground to particle size less than 325 mesh, that is, it is made into.The present application method controls the composition of powder in reasonable range by homogenization, combined with magnetic separation, leaching, complexing selective impurity removal, improve the whiteness of final product;The setting of calcination system can control the COD level of product and inhibit the generation of mullite, so that the product meets the standard of calcined kaolin for glass fiber, and the coal gangue can be used to prepare calcined kaolin for glass fiber at low cost.

The invention discloses ultra-white quartz sand, raw materials for manufacturing the ultra-white quartz sand comprise quartz ore and a composite fluxing agent, raw materials for manufacturing the composite fluxing agent comprise sodium chloride powder and potassium chloride, the mass fraction of the quartz ore is 100 parts, and the mass fraction of the composite fluxing agent is 0.9-1.1 parts. The high-purity quartz ore and high-precision color sorting equipment are adopted, visible impurities and part of harmful impurities are preliminarily removed, a good foundation is laid for the subsequent process, the arranged composite pickling solution contains hydrochloric acid, concentrated sulfuric acid and oxalic acid, compared with a single pickling solution, different types of impurities can be removed in a targeted mode, and the production efficiency is improved. The removal rate of impurities such as iron and aluminum is obviously improved; and secondly, sodium chloride powder and potassium chloride are added as fluxing agents in the drying and calcining process, and two-stage calcining and inert gas protection are adopted, so that trace impurities can be further removed, the crystal structure of the quartz ore can be optimized, and the whiteness and purity of the product can be improved.

The present invention relates to a thermoplastic resin composition, a method for preparing the same, and a molded article comprising the same. More specifically, the present invention relates to a thermoplastic resin composition, a method for preparing the same, and a molded article comprising the same; the thermoplastic resin composition comprises: 4 wt% to 31 wt% of an alkyl acrylate-aromatic vinyl compound-vinyl cyanide graft copolymer (A-1) containing an alkyl acrylate rubber having an average particle diameter of 50 nm to 150 nm; 1 wt% to 22 wt% of an alkyl acrylate-aromatic vinyl compound-vinyl cyanide graft copolymer (A-2) containing an alkyl acrylate rubber having an average particle diameter of more than 150 nm and 600 nm or less; 55 wt% to 77 wt% of an aromatic vinyl compound-vinyl cyanide copolymer (B); 7% to 12.5% by weight of a white pigment (C); and 3.5 wt% to 8 wt% of a white pigment auxiliary (D) having an average particle size of 2 [mu] m or less. According to the present invention, the present invention has the following effects: providing a thermoplastic resin composition, a method for preparing the thermoplastic resin composition, and a molded article comprising the thermoplastic resin composition; the thermoplastic resin composition maintains the excellent physical properties of conventional ASA-based resins, achieves high whiteness even if the input amount of white pigment is reduced, has excellent film processability, hiding power, and glossiness, has excellent appearance quality without protrusions on the surface of a sheet, and reduces manufacturing costs.

The invention provides a method for preparing melamine polyphosphate at low temperature, and relates to the field of melamine polyphosphate. The method for preparing melamine polyphosphate at low temperature comprises the following steps: dispersing polyphosphoric acid, reacting at low temperature and post-treating. The method for preparing melamine polyphosphate at low temperature can solve the problems of high intermediate dehydration temperature, complex process, high production cost and energy consumption, poor product chromaticity and stability, difficult solvent recovery and prominent safety and environmental protection risks in the existing production process; the melamine polyphosphate with good chromaticity and stability can be prepared in one step on the premise that high-temperature dehydration and solvent recovery are not needed, the process is simple and controllable, the production cost is low and the equipment requirement is low.

The application relates to a production method of titanium white powder for polycarbonate with high gloss and impact resistance. The method is as follows: slushing titanium dioxide primary powder, dispersing the titanium dioxide with silicate after pH adjustment, sand grinding, coating a first layer of mixed film of loose silicon oxide and aluminum oxide under wet alkaline condition, coating a third layer of barium sulfate film under acid condition with pH=5.5-6.5, pressure filtration, drying, air powder treatment, adding isopropyl tri(dioctyl phosphoric acid acyl oxygen) titanate during air powder treatment, and obtaining the product. The method has the advantages of simple process, easy operation, high gloss and high impact resistance of polycarbonate products by adding a small amount of titanium white powder, processing stability, high whiteness of polycarbonate products and light weight.

The present application relates to a kind of calcium hydroxide / natural zeolite composite humidity control material and its preparation method, belong to non-metallic mineral functional materials and inorganic humidity control material field.The natural zeolite of the present application is made into ore pulp by adding water, while according to the preset Ca (OH) 2 coating amount and the reaction molar ratio of NaOH and CaCl2 to react to generate Ca (OH) 2 NaOH and CaCl2 are weighed, and water is added to configure into respective uniform solution respectively;After that, NaOH solution and CaCl2 solution are added to natural zeolite ore pulp in parallel flow, and Ca (OH) 2 is uniformly precipitated and coated on the surface of natural zeolite particles;Prepared Ca (OH) 2 / natural zeolite composite powder suspension with certain liquid-solid ratio;Then Ca (OH) 2 / natural zeolite composite powder suspension is hydrothermally reacted;Finally, the hydrothermal reaction product is filtered, washed, dried and depolymerized, and the calcium hydroxide / natural zeolite composite humidity control material is prepared.The present application significantly improves the humidity control performance of natural zeolite, and the preparation method is energy-saving and green environmental protection, has greater application value and good application prospect in the field of building humidity control material.

This invention discloses an aluminum ash calcination denitrification whitening agent, its preparation method, and its application. By weight, the whitening agent comprises: 80-94 parts of grinding coating agent, 45-72 parts of hydrotalcite, 42-50 parts of perlite powder, 100-128 parts of diatomaceous earth, 58-65 parts of combustion aid, 75-90 parts of dispersant, 100-120 parts of adsorption and penetrating agent, 15-172 parts of dendritic mesoporous silica hollow spheres, 30-40 parts of aluminum wire, 280-300 parts of alumina, and 18-26 parts of silicate. At room temperature, the adsorbent and penetrant are mixed and stirred with the treated aluminum ash, and a dispersant is added and the mixture is stirred further. A grinding coating agent, hydrotalcite, perlite powder, diatomaceous earth, combustion improver, dendritic mesoporous hollow silica spheres, alumina, and silicates are added and thoroughly mixed to obtain a final mixture. The mixture is then sprayed into a burner in powder form and reacted with air. After stirring and calcination, aluminum wire is added and stirred and calcined again, followed by stirring and cooling to room temperature. This invention achieves the removal of toxic components from aluminum ash and the improvement of the whiteness of the calcined product.

This invention discloses a method for producing high-quality nano-calcium carbonate from desulfurization ash, comprising the following steps: magnetic separation of the desulfurization ash; mixing the magnetically separated desulfurization ash with water to obtain a first desulfurization ash slurry; adding a mixed solution of sodium acetate and hydrochloric acid to the first desulfurization ash slurry, reacting to obtain a second desulfurization ash slurry with an acidic pH, and collecting the CO2 generated during the reaction; performing solid-liquid separation on the second desulfurization ash slurry to obtain the byproduct calcium sulfite and a mixed solution of calcium acetate and sodium chloride; adding sodium hydroxide to the mixed solution of calcium acetate and sodium chloride to adjust the pH to alkaline, and then performing solid-liquid separation to obtain metal hydroxide slag and a mixed solution of calcium acetate and sodium chloride; statically mixing the mixed solution of calcium acetate and sodium chloride with a sodium carbonate solution containing sodium tripolyphosphate using a peristaltic pump, and separating to obtain solid nano-calcium carbonate. This invention achieves the resource utilization of desulfurization ash and also prepares high-quality nano-calcium carbonate.

The application belongs to the technical field of papermaking, and provides a food contactable double-coated copper-coated card paper, a preparation method and application thereof. The food contactable double-coated copper-coated card paper comprises, from the front side to the back side, a front side surface coating layer, a front side base coating layer, a base paper, a back side base coating layer and a back side surface coating layer which are sequentially stacked, and the base paper comprises, from the front side to the back side, a surface layer, a core layer and a bottom layer which are sequentially stacked, the front side base coating layer and the back side base coating layer are obtained by coating a first coating material, and the front side surface coating layer and the back side surface coating layer are obtained by coating a second coating material, wherein the first coating material comprises the following components: 65-grade ground calcium carbonate, a first latex and a starch-acrylate graft copolymer, and the second coating material comprises the following components: 95-grade ground calcium carbonate, a second latex and a starch-acrylate graft copolymer. The double-coated copper-coated card paper has the advantages of high printing surface strength, high gloss, low surface roughness, low difference between two sides and low heavy metal content.

The invention provides a bleaching control process for low-DCM extract sulfate hardwood pulp, and relates to the technical field of pulping and papermaking. By adjusting an existing pulping four-section bleaching process, the using amount of hydrogen peroxide in the EOP section and the using amount of chlorine dioxide in the D1 section are increased, chlorine dioxide in the D2 section is stopped, the using amount of chlorine dioxide in the front section of pulp papermaking is reduced, DCM extract rising from D2 wet pulp to a finished product pulp board is avoided, low-level control over the stable content of DCM extract in the pulp board product is achieved, and the production efficiency is improved. And the whiteness of the pulp board reaches 89.5% ISO or above, and the pulp board can meet the requirements of high-whiteness paper such as paper for daily use and the like.