177 results about "Black liquor" patented technology

The invention discloses a ZnO / PES mixed matrix ultrafiltration membrane and a polyaniline-ZnO / PES mixed matrix nanofiltration membrane as well as a preparation method and an application of the ZnO / PES mixed matrix ultrafiltration membrane and the polyaniline-ZnO / PES mixed matrix nanofiltration membrane. PES is used as an organic polymer, PEG1500 is used as a pore-foaming agent, ZnO is used as a nano filler, and the ZnO / PES composite ultrafiltration membrane is prepared through a non-solvent induced phase inversion method. The preparation method comprises the following steps: synthesizing a polyaniline coated ZnO nano composite material, blending zinc nitrate hexahydrate in ammonia water with a polyaniline solution to form a nano composite structure, and preparing the polyaniline-ZnO / PES mixed matrix nanofiltration membrane by taking the synthesized nano composite particles as a filler. According to the mixed matrix membrane technology, alkali and lignin in the black liquor can be directly recovered, compared with alkali recovery through a combustion method, the mixed matrix membrane technology has the advantages of being easy to operate, not complex in process, low in investment cost, small in occupied area, low in energy consumption, good in environmental compatibility and the like, and meanwhile subsequent high-valued comprehensive utilization can be conducted on lignin.

The invention belongs to the technical field of green chemistry and sustainable chemical engineering, and discloses a method for recovering an acidic eutectic solvent by combining anti-solvent precipitation with activated carbon adsorption. Water-insoluble high-molecular-weight lignin in the deep eutectic solvent black liquor is removed by an anti-solvent precipitation technology, and then residual low-molecular-weight water-soluble lignin and polysaccharide in the solution are further adsorbed and removed by using activated carbon with high specific surface area and rich pore structure; and the eutectic solvent with high purity and unobviously changed structure is recovered. The method is suitable for various acidic deep-eutectic solvents, the operation is simple, water and activated carbon in the recovery process can be repeatedly used, and the obtained water-insoluble lignin, water-soluble lignin and polysaccharide have high application value.

The invention provides a method for researching membrane pollution of lignin particles in porous ceramic membrane filtration, which simulates the process of filtering black liquor lignin by a porous ceramic membrane based on a developed semi-analytical DEM-CFD coupling interface. The method mainly studies the formation mechanism of membrane pollution and the type of membrane pollution in the process of filtering black liquor lignin by the porous ceramic membrane, analyzes the influence of lignin particle concentration and particle size and black liquor flow velocity on the porous ceramic membrane filtration process, and further obtains the influence of lignin particle concentration and particle size and black liquor flow velocity on membrane pollution. And theoretical basis and microscopic information are provided for selection of subsequent membrane pollution control methods.

The present application relates to biomass high-value utilization technical field, more specifically to a kind of papermaking by-product black liquor high-value water phase preparation lignin amine cationic surfactant method, comprising the following steps: pulping black liquor is adjusted pH with acid or alkali, centrifugal to take upper clear liquid, add epoxy chloropropane, temperature is raised to certain temperature and is reacted for 30min.Then, add amine reagent and react for a certain time, after cooling, centrifugal, wash after the lower layer precipitate is dried to obtain lignin amine cationic surfactant.The present application not only can make papermaking by-product black liquor waste into treasure-high-value water phase synthesis lignin amine cationic surfactant, and the preparation process of the lignin amine cationic surfactant is simple, energy consumption is low, the whole process is green, no waste water discharge, without black liquor purification, without adding formaldehyde, also without alkali recovery;Easy to realize industrial production, with broad market prospect.

Methods, apparatuses, and systems for extracting lignin from non-wood black liquor are disclosed. The non-wood black liquor is heated to a first temperature to degrade hemicelluloses contained therein. The liquid is then cooled to a second temperature. The pH of the cooled liquid is chemically reduced to precipitate lignin from the liquid. The liquid is filtered to separate the precipitated lignin from the liquid.

The application discloses a preparation method of a pesticide lignosulfonate sodium dispersant composition and belongs to the technical field of dispersants. The method comprises the following steps: S1, taking papermaking black liquor as raw material, performing standing precipitation, flocculation precipitation, membrane concentration and acid precipitation treatment to obtain purified lignin; S2, adding the purified lignin into water, adjusting the pH of the system to 10-11, then adding hydrogen peroxide to perform pre-oxidation, then adding formaldehyde and sodium sulfite to perform sulfomethylation reaction, and adding formaldehyde to perform polycondensation reaction; cooling and discharging, and performing spray drying to obtain lignosulfonate sodium; and S3, adding the lignosulfonate sodium and 1-ethyl-3-methyl imidazolium L-lactate into water and stirring and uniformly mixing, adding stevioside to perform ultrasonic treatment, forming a homogeneous system, and performing spray drying to obtain the pesticide lignosulfonate sodium dispersant composition. The lignosulfonate sodium dispersant composition can effectively improve the pesticide dispersion stability and pesticide biological activity, and meets the pesticide use requirement.

This invention discloses a rice straw-based liquid mulch film emulsion, its preparation method, and its application. The preparation method includes: treating pretreated rice straw with an alkaline solution in sodium hydroxide to obtain rice straw fibers and a silicon-containing black liquor; washing and bleaching the rice straw fibers to obtain bleached rice straw fibers; allowing the silicon-containing black liquor to stand, adjusting the pH value, and allowing it to stand again to obtain a silicon-containing dispersion; mixing and activating the bleached rice straw fibers with an alkaline alcohol solution, followed by etherification with chloroacetic acid to obtain carboxymethyl cellulose; mixing polyvinyl alcohol and carboxymethyl cellulose solutions, adding the silicon-containing dispersion under stirring, and then adding water to obtain the rice straw-based liquid mulch film emulsion. The rice straw-based liquid mulch film emulsion prepared by this invention can be used for soil covering in cultivated soils, exhibiting excellent film-forming strength, toughness, light-blocking properties, and soil cover adaptability. It has a wide range of raw material sources, a simple preparation process, and is suitable for large-scale promotion.

The present invention discloses a sodium ion battery hard carbon material, a preparation method thereof, and a sodium ion battery using the hard carbon material. The hard carbon material is a composite porous material inlaid with hollow porous spheres and porous carbon sheets. Compared with the prior art, the advantages of the present invention are: a method for preparing sodium ion hard carbon materials from concentrated papermaking black liquor in a short process using spray pyrolysis, using spray pyrolysis to construct a precursor material with a hollow porous spherical structure; using an aqueous solution to collect the precursor material, and removing impurities through solid-liquid separation and washing; and then further regulating the microstructure of the carbon material through two-stage heat treatment to obtain a hard carbon negative electrode material with high specific capacity, excellent rate performance, and cycle stability. Using the hard carbon material as the negative electrode, a high-energy-density sodium ion battery is prepared.

The invention relates to a composition comprising a hydraulic binder, optionally a fly ash aggregate, and at least one additive, wherein the additive is a combustion residue obtained from the combustion of black liquor, and wherein the additive is present in a concentration of 0.01% to 6.0% by weight based on the total amount of the composition. The invention further relates to a building material containing this composition.

The present invention relates to a method for preparing cross-linked lignin in the form of particles using hydrothermal treatment with a liquid made from black liquor, comprising lignin and a cross-linking agent or a precursor thereof, and having an electrical conductivity of more than 15 mS / cm, preferably more than 25 mS / cm to 400 mS / cm. The present invention also relates to cross-linked lignin produced using the above-mentioned method. The present invention also relates to cross-linked lignin particles having a glass transition temperature Tg of at least 160°C or no glass transition temperature and a STSA surface area of at least 10 m 2 / g. The present invention also relates to rubber articles, in particular industrial rubber articles or tires, comprising cross-linked lignin particles as filler.

The utility model relates to a multistage flash evaporation and vacuum low-temperature negative-pressure black liquor concentration system based on industrial waste heat, which belongs to the technical field of flash evaporation and comprises at least one heat exchange unit and at least two flash evaporation units sequentially connected in series. The concentration medium outlet of the flash evaporation unit located at the last effect is communicated with the concentration medium inlet of the heat exchange unit equivalent to the flash evaporation unit of the last effect located at the last effect, and when the number of the heat exchange units is at least two, the heat exchange units are sequentially connected in series. The flash evaporation unit located at the first effect communicates with the heat exchange unit equivalent to the flash evaporation unit located at the first effect through a heating unit. The concentration medium generated by the last-effect flash evaporation unit flows back to the previous-effect heat exchange unit to serve as a heat source, energy recycling is achieved, the requirement for external heat input is reduced, and therefore the energy efficiency of the whole system is improved; the plurality of heat exchange units which are sequentially connected in series can more effectively utilize temperature gradient to transfer heat, so that the heat can be more uniformly transferred to each flash evaporation unit, and the heat transfer effect is enhanced.

The invention discloses a preparation method of a nitrogen-sulfur co-doped lignin-based hierarchical porous carbon material and supercapacitor energy storage application, and belongs to the technical field of preparation methods and application of porous carbon materials, and the preparation method comprises the following steps: (1) dropwise adding an ammonium sulfate solution into sulfate pulping black liquor, and adjusting the pH value, after standing reaction, drying to obtain ammonium sulfate precipitated lignin; (2) uniformly mixing lignin with potassium tartrate and potassium nitrate, drying and grinding to obtain a mixture; and (3) pyrolyzing the mixture in an inert atmosphere, washing the carbonized product with dilute acid, filtering, and drying to obtain the porous carbon material. Potassium tartrate promotes formation of graded pores through the mild pore-forming effect, and the foaming effect of potassium nitrate can inhibit formation of coal tar and excessive carbon skeleton etching in the pyrolysis process. The supercapacitor electrode material prepared from the porous carbon has high specific capacitance, excellent cycling stability and high energy density.

Compositions and methods for the removal and prevention of scale in pulp mills in a continuous and real-time process. More particularly the composition includes one or more chelating ligands, one or more copolymers, and one or more surfactants. The scale removing composition is added to the black liquor stream in pulp and paper processes to remove scaling, such as scaling from calcium carbonate, from surfaces in contact with the black liquor stream, such as in digestors and evaporators.

The invention provides a composite geopolymer material as well as a preparation method and application thereof, and belongs to the technical field of geopolymer materials. The method comprises the following steps: providing initial alkalinity and soluble salt ions of a system by using papermaking black liquor ash, providing an aluminum-silicon precursor by using coal gangue powder, obtaining geopolymer slurry with proper rheology through coupling regulation and control of proportion, granularity and water-binder ratio, and forming the geopolymer slurry into a sample blank; then absorbing industrial furnace tail gas by using a composite amine solution to prepare a CO2-rich solution, soaking the sample blank for a short time to enable the CO2-rich solution to uniformly permeate into pores, heating in a medium-low temperature and high humidity environment to promote the CO2-rich solution to slowly release CO2 into the plate, and synchronously evolving with a gel network to form uniform and stable carbonate microcrystals and compact pore walls, so as to achieve the purpose of improving the performance of the plate. According to the process, the surface layer density and the size stability are rapidly improved, meanwhile, CO2 resource solid storage and amine liquid closed-loop circulation are achieved, NaOH / water glass does not need to be additionally added, the corrosivity and the safety risk are low, and the process is suitable for continuous industrial production.

The invention discloses a lignin-styrene-butadiene latex core-shell material, a preparation method thereof and application of the lignin-styrene-butadiene latex core-shell material in a PE composite material, and the preparation method comprises the following steps: dissolving lignin in an organic solvent to obtain a lignin solution; the preparation method comprises the following steps: adding an emulsifier and distilled water into a reaction kettle, stirring, dropwise adding a lignin solution to form a stable oil-in-water emulsion, dropwise adding an initiator, styrene and butadiene into the oil-in-water emulsion, carrying out a thermal insulation reaction, and carrying out suction filtration, washing and drying to obtain the lignin-styrene-butadiene latex core-shell material. In addition, the core-shell material, PE, a plasticizer, a lubricant, an anti-blocking agent and the like are subjected to blending, extrusion granulation and film blowing forming, and the PE composite material is prepared. The core-shell structure effectively shields polar functional groups on the surface of the lignin, and obviously improves the compatibility and dispersity of the lignin in a PE matrix, so that the mechanical property of the composite film is enhanced, the surface defects are obviously reduced, and the high-valued resource utilization of the lignin in the papermaking black liquid is realized.

The invention discloses a method for pulping by using sugarcane leaves, and belongs to the technical field of pulping and papermaking. The method comprises the following technical steps: (1) pretreatment of sugarcane leaves: immersing crushed sugarcane leaves into a mixed solution, carrying out microwave irradiation, and filtering to obtain a cooked material; (2) two-stage cooking: putting the cooking material into cooking liquor containing a composite cooking agent, and carrying out first-stage cooking, so as to obtain first slurry; a silicon dispersing agent is added into the first slurry for second-stage cooking, and second slurry is obtained; and (3) pulping: carrying out solid-liquid separation, washing and screening on the second pulp to prepare paper pulp. The method for pulping by using sugarcane leaves has the advantages of high desilicication rate, high lignin removal rate, high cellulose retention rate, small amount of alkali (sodium hydroxide) required in the production process, low viscosity of black liquid, low equipment scaling possibility, low equipment cleaning frequency, high production efficiency and low production cost.

This invention discloses a method for preparing hard carbon derived from the aerial roots of banyan trees, belonging to the field of new energy materials technology. The method includes the following steps: Step 1: Freshly cut banyan aerial roots are washed, dried, crushed, and sieved; Step 2: Choline chloride (ChCl) and lactic acid (LA) are mixed in a certain proportion to prepare DES; Step 3: The DES from Step 2 is mixed with the banyan aerial root powder from Step 1 and reacted, then subjected to delignification. The delignified black liquor is washed with anhydrous ethanol and deionized water and filtered to obtain a filter cake, which is then dried in an oven; Step 4: The filter cake from Step 3 is ground into powder and calcined at a medium-low temperature to obtain pre-carbonized banyan aerial root powder; Step 5: The pre-carbonized powder from Step 4 is calcined at a medium-high temperature, acid-washed, and dried to obtain banyan aerial root-derived hard carbon. This invention discloses a green, environmentally friendly, and high-performance method for preparing derived hard carbon, applicable to battery anode materials, realizing the high-value utilization of biomass waste.

The invention discloses a hydroxymethylated superfine lignin modified degradable mulching film and a preparation method thereof. The hydroxymethylated superfine lignin modified degradable mulching film comprises the following components in parts by weight: 60-89 parts of PBAT, 1-10 parts of PLA, 10-30 parts of hydroxymethylated superfine lignin, 0.1-5 parts of a plasticizer, 0.1-3 parts of a light stabilizer, 0.1-3 parts of an antioxidant, 0.1-5 parts of a lubricant and 0.1-5 parts of an anti-blocking agent. A preparation method of the hydroxymethylated superfine lignin comprises the following steps: filtering papermaking black liquor, adding the filtered papermaking black liquor and formaldehyde into a reaction kettle, fully reacting at 70-90 DEG C and 300-600 rpm for 2-5 hours, cooling to room temperature after the reaction is complete, and carrying out precipitation, filtering, drying and ultrasonic treatment to obtain the 20-300 nm hydroxymethylated superfine lignin. The papermaking black liquid is selected as the raw material, so that the raw material cost of the biodegradable mulching film is reduced. Besides, the aldehyde modifier reacts with lignin to form nanoscale hydroxymethylated superfine lignin, so that the dispersity and compatibility of the nanoscale hydroxymethylated superfine lignin in a degradable material are improved, the mechanical strength of the biodegradable mulching film is further improved, and the outdoor use time of the biodegradable mulching film can be prolonged.

The application relates to the technical field of ion batteries, and discloses a nitrogen-doped carbon material and a preparation method and application thereof, wherein the preparation method of the nitrogen-doped carbon material comprises the following steps: (1) adding an acidic solution into papermaking black liquor to obtain alkali lignin; (2) dissolving the alkali lignin in a mixed solution of ammonia water and an organic solvent to obtain an alkali lignin solution; (3) carrying out hydrothermal reaction on the alkali lignin solution to obtain a pre-nitrogenation product; and (4) mixing the pre-nitrogenation product with calcium chloride, drying and pyrolyzing to obtain the nitrogen-doped carbon material; the pyrolysis temperature is 400-800 DEG C, and the pyrolysis time is 3-5 h. The nitrogen-doped carbon material is prepared by taking papermaking black liquor as a biomass raw material, efficient utilization of waste is realized, nitrogen elements in the nitrogen-doped carbon material are uniformly distributed in a carbon skeleton, the nitrogen content and the specific surface area of the nitrogen-doped carbon material can be accurately controlled through a pyrolysis process, and the adsorption and storage behaviors of the nitrogen-doped carbon material for potassium can be quantitatively controlled.

The utility model relates to the technical field of papermaking, in particular to bamboo pulp black liquor extraction equipment for a paper mill, which not only prevents impurities in black liquor from being blocked in a filter screen and avoids the trouble of frequently cleaning the filter screen, but also improves the filtration and extraction efficiency and accelerates the extraction of the black liquor. Comprising a filtering mechanism; the device further comprises an extrusion mechanism, a stirring mechanism, a distillation mechanism and an air extraction mechanism, the extrusion mechanism is installed on the filtering mechanism and extrudes the black liquor, the stirring mechanism is installed on the extrusion mechanism and pretreats the black liquor, the distillation mechanism is installed on the filtering mechanism and distills the black liquor, and the air extraction mechanism is installed on the distillation mechanism and extracts steam.

This invention provides a low-cost and environmentally friendly papermaking pulping process, comprising the following steps: S1. Pretreatment of papermaking fiber plant raw materials. S2. Oxy-alkali cooking: The pretreated papermaking fiber plant raw materials are mixed with an aqueous sodium carbonate solution, and cooked for 0.5–5 hours using oxygen as an oxidant. Then, sodium hydroxide is added, and cooking continues for 0.3–2 hours. Finally, the pulp and black liquor are separated by pressing. S3. Black liquor treatment: The black liquor is mixed with fiber waste, pressed, and burned as biomass fuel. S4. Recovery and causticization. This papermaking pulping process uses sodium carbonate and a small amount of sodium hydroxide for staged oxy-alkali pulping, and the generated black liquor is mixed with fiber waste and burned to recover sodium carbonate and heat, reducing the causticization rate and pulping costs.

The application discloses an acid pickling corrosion inhibitor prepared based on bamboo pulp papermaking black liquor, and a preparation method and application thereof, and relates to the technical field of acid pickling corrosion inhibitors. The method comprises the following steps: (1) adding concentrated sulfuric acid into the bamboo pulp papermaking black liquor, adjusting the pH value of the solution to 1-3, and then fully reacting, standing and settling, and separating to obtain a precipitate A and a filtrate A; the precipitate A is washed and dried to obtain lignin; (2) the filtrate A is concentrated through multi-effect vacuum reduced pressure evaporation to obtain a precipitate B; (3) the precipitate B is extracted through sewage ethanol extraction, suction filtration and washing to obtain an ethanol extraction liquid and a precipitate C; the ethanol extraction liquid is distilled through reduced pressure distillation to obtain an ethanol extraction liquid; the precipitate C is recrystallized, and after removing solid inorganic salts, the precipitate C is distilled through reduced pressure distillation to obtain a distillation liquid; the ethanol extraction liquid and the distillation liquid are mixed, and then evaporated through reduced pressure evaporation and dried to obtain the acid pickling corrosion inhibitor.

The application discloses a method for preparing bio-oil by co-pyrolysis of black liquor solids and waste plastics with Ni-Mo / HZSM-5 as a catalyst, and high-quality bio-oil is prepared by co-pyrolysis of black liquor solids and waste plastics with Ni-Mo / HZSM-5 as a catalyst. Research shows that the addition of plastics can significantly improve the yield of hydrocarbons. The total hydrocarbon of black liquor solids, black liquor solids and polypropylene, and black liquor solids and polyethylene increases by 6%, 78% and 45% respectively under the catalytic pyrolysis of Ni-Mo / HZSM-5, and waste plastics have a synergistic effect on the pyrolysis of black liquor solids. When black liquor solids and polyethylene are co-pyrolyzed, the yield of alkanes is the highest at 69.44% at a temperature of 650 DEG C. When black liquor solids and polypropylene are co-pyrolyzed, the yield of alkanes is the highest at 44.9% at a temperature of 550 DEG C. The obtained pyrolysis bio-oil is mainly composed of hydrocarbons, and is a kind of high-quality bio-oil.

The invention belongs to the technical field of bio-based composite materials and functional packaging materials, and discloses a method for extracting nano lignin in papermaking black liquor, a lignin-based composite membrane and a preparation method thereof.The method comprises the steps that polyhydroxyalkanoate and a nano lignin solution are mixed and subjected to a water-bath heating reaction for 4-8 h under the air isolation condition, and after the water-bath heating reaction is completed, the lignin-based composite membrane is obtained; performing ultrasonic treatment to obtain reaction liquid; and pouring the reaction liquid into a film, and drying to obtain the film. Compared with a pure PHA membrane, the mechanical property of the composite membrane is greatly improved.

Methods, apparatuses, and systems for extracting lignin from non-wood black liquor are disclosed. The non-wood black liquor is heated to a first temperature to degrade hemicelluloses contained therein. The liquid is then cooled to a second temperature. The pH of the cooled liquid is chemically reduced to precipitate lignin from the liquid. The liquid is filtered to separate the precipitated lignin from the liquid.

This utility model relates to a black liquor concentration multi-effect evaporation tail gas recovery and utilization system, belonging to the field of energy-saving and environmental protection technology. The tail gas pipeline of the last effect of the multi-effect evaporation system is connected to the medium inlet on one side of the first heat exchanger. The other side of the first heat exchanger establishes black liquor medium circulation with the flash evaporator through a circulation pump. The exhaust steam generated by the flash evaporator enters the condenser through a channel. The flash evaporator is connected to the black liquor medium inlet of the multi-effect evaporation system through a black liquor discharge pipeline. A black liquor feed pipeline is provided on the other side of the first heat exchanger. This application significantly improves the energy cascade utilization efficiency and greatly reduces the overall energy consumption. The system recovers the waste heat of the tail gas of the last effect of the multi-effect evaporation system through the first heat exchanger, transferring the "waste heat energy" to the dilute black liquor to be concentrated, providing a heat source for the negative pressure flash evaporation of the flash evaporator; at the same time, the second heat exchanger realizes the heat exchange between the low-temperature feed dilute black liquor and the high-temperature pre-concentrated black liquor, tapping the potential for heat utilization.

The present invention relates to the field of papermaking black liquor resource utilization, and specifically to a method for recovering alkali and lignin from papermaking black liquor using cationic exchange dialysis. The method comprises the following steps: 1) ammonium ion exchange dialysis: using a cationic exchange dialysis device, the papermaking black liquor is passed through the cationic exchange dialysis device and subjected to cationic exchange dialysis with an aqueous solution containing ammonium ions to obtain desalted ammoniacal papermaking black liquor; 2) ammonia recovery: recovering ammonia from the desalted ammoniacal papermaking black liquor obtained in step 1) to obtain ammonia or ammonia water and desalted and dealkalized papermaking black liquor; 3) lignin separation: separating the precipitated lignin from the desalted and dealkalized papermaking black liquor obtained in step 2) to obtain a lignin precipitate and desalted, dealkalized and delignified papermaking black liquor. The method can simultaneously recover alkali and lignin from the papermaking black liquor and achieve desalination of the papermaking black liquor, with low energy consumption, low membrane fouling, and high alkali and lignin recovery rates.

The invention discloses a spatial reticular silicon paste type defoaming agent as well as a preparation method and application thereof. The preparation method comprises the following steps: putting fluorine-containing ethynyl MQ silicon resin, hydrogen-containing silicone oil, hydroxyl silicone oil, hydrophobic SiO2 and dimethyl silicone oil into a reaction kettle, carrying out nitrogen protection, stirring and heating to 65-90 DEG C, adding chloroplatinic acid, carrying out an addition reaction for 0.5-2 hours, then adding a base catalyst, continuing to heat to 120-140 DEG C, carrying out a condensation polymerization reaction for 2-4 hours, cooling and discharging to obtain spatial reticular silicon paste; mixing the spatial reticular silicon paste, the polyether modified silicone oil, polyether and the emulsifier, stirring and heating to 55-65 DEG C, adding deionized water for phase inversion emulsification, cooling, adding deionized water, and adding the thickener to obtain the spatial reticular silicon paste type defoaming agent. Compared with the traditional silicon paste type defoaming agent in papermaking pulping, especially chemical pulping, the defoaming agent prepared by the invention has the characteristics of high black liquor defoaming speed, good foam inhibition property, good pulp washing water filtration property, no toxicity, no harm and simple preparation process.

The invention discloses a method for preparing high-quality light calcium carbonate based on green liquid separation and impurity removal-crystal nucleus induction causticization granulation, and relates to the technical field of pulping and papermaking waste liquid treatment. According to the method, pulping black liquor is used as a raw material, calcium silicate is separated through fractional precipitation, granular calcium carbonate crystals are generated through crystal nucleus induction causticization reaction, and high-quality light calcium carbonate is prepared through multi-stage purification. The content of calcium carbonate prepared by the method can reach 98-99.5% of the purity of industrial calcium carbonate, the purity of calcium silicate byproducts is greater than or equal to 90%, the calcium silicate byproducts can be directly used for roadbed materials or cement retarders, the recovery rate of sodium hydroxide in the black liquor is greater than or equal to 92%, and resource utilization is realized.