CN112299475A - Nanometer titanium dioxide for ultra-pure high-specific-surface-area denitration and preparation method thereof - Google Patents

Nanometer titanium dioxide for ultra-pure high-specific-surface-area denitration and preparation method thereof Download PDF

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CN112299475A
CN112299475A CN202011208619.3A CN202011208619A CN112299475A CN 112299475 A CN112299475 A CN 112299475A CN 202011208619 A CN202011208619 A CN 202011208619A CN 112299475 A CN112299475 A CN 112299475A
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titanyl sulfate
agglomerated
less
controlled
titanium dioxide
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荚玉冬
赵志国
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Anhui Dino Environmental Protection New Material Technology Co ltd
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Anhui Dino Environmental Protection New Material Technology Co ltd
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    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
    • C01G23/00—Compounds of titanium
    • C01G23/04—Oxides; Hydroxides
    • C01G23/047—Titanium dioxide
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J21/00—Catalysts comprising the elements, oxides, or hydroxides of magnesium, boron, aluminium, carbon, silicon, titanium, zirconium, or hafnium
    • B01J21/06—Silicon, titanium, zirconium or hafnium; Oxides or hydroxides thereof
    • B01J21/063—Titanium; Oxides or hydroxides thereof
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B82—NANOTECHNOLOGY
    • B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
    • B82Y30/00—Nanotechnology for materials or surface science, e.g. nanocomposites
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B82—NANOTECHNOLOGY
    • B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
    • B82Y40/00—Manufacture or treatment of nanostructures
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2006/00—Physical properties of inorganic compounds
    • C01P2006/12—Surface area
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2006/00—Physical properties of inorganic compounds
    • C01P2006/80—Compositional purity
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2006/00—Physical properties of inorganic compounds
    • C01P2006/80—Compositional purity
    • C01P2006/82—Compositional purity water content

Abstract

The invention discloses a nano titanium dioxide for ultra-pure high specific surface area denitration and a preparation method thereof, wherein the preparation method comprises the following steps: (1): carrying out acidolysis, sedimentation, hot filtration, crystallization, ferrous separation and controlled filtration on the titanium concentrate to obtain a relatively pure titanyl sulfate solution; (2): freezing and crystallizing the titanyl sulfate solution, and then carrying out solid-liquid separation to obtain a titanyl sulfate filter cake; (3): concentrating the obtained titanyl sulfate filter cake, and hydrolyzing by adding seed crystals under micro pressure to obtain larger agglomerated particle size; (4): bleaching the agglomerated titanyl sulfate by three-washing and one-bleaching; (5): heating the titanyl sulfate obtained in the step (4) to 50-65 ℃ by steam, adjusting the titanyl sulfate to 20-50 g/l, and controlling the dried finished product S to be less than or equal to 2000 ppm; (6): and pressing and calcining in a rotary kiln. The invention has the beneficial effects that: simple process flow, low manufacturing cost, high product purity, low sulfate radical content and strong low-temperature poisoning resistance.

Description

Nanometer titanium dioxide for ultra-pure high-specific-surface-area denitration and preparation method thereof
Technical Field
The invention relates to the field of environment-friendly materials, in particular to a Selective Catalytic Reduction (SCR) flue gas denitration catalyst carrier material TiO2The preparation technique of (1).
Background
At present, the mainstream denitration technology of the boiler of each enterprise in China is an SCR flue gas denitration technology, the core of the SCR denitration technology is an SCR denitration catalyst, and the SCR denitration catalyst is mainly divided into three types according to the shape: the honeycomb, plate and corrugated plate type catalysts have the advantages of small occupied area, strong poisoning resistance, easiness in replacement, good maintenance and the like under the same catalysis condition, and occupy most of the market share, but the plate type catalysts are more suitable for the environment with severe catalysis conditions due to the structural characteristics of the plate type catalysts, have the advantages of strong gas permeability, pressure reduction and the like, and also become a non-negligible component part of the SCR denitration catalyst market.
The mainstream production technology of the SCR plate type catalyst at abroad is to use nano titanium dioxide with ultrahigh specific surface area for denitration and 100m of specific surface area2The nano titanium dioxide for denitration near/g is mixed according to a certain proportion, then is mixed, coated, dried and calcined to produce the plate-type catalyst, and the nano titanium dioxide for denitration with ultra-high specific surface area has low crystallinity, small single crystal particles (6-8 nm) and 100m specific surface area2The mixing of the/g denitration titanium dioxide (the single crystal particles are 16-20 nm) can better fill the pores of respective powder, and the wear-resisting strength of the coating layer can be effectively increased while the catalytic specific surface area is improved.
At present, the domestic nano titanium dioxide for denitration with ultra-high specific surface area has relatively low localization degree due to the technical barriers of small amount, high production cost, difficult control of specific surface area and the like. Even the imported nano titanium dioxide with ultra-high specific surface area for denitration is used for medium-high temperature catalysts, the sulfate radical content of the powder is high and is about 2.5-3%. Can better inhibit SO at a high-temperature section2/SO3However, the conversion rate of (2) is problematic in the application of low-temperature plate catalysts, and the produced ammonium sulfate salt is more, which results in catalyst poisoning.
Chinese patent publication No. CN107298460B discloses titanium dioxide with low sulfur and ultrahigh specific surface area, and a preparation method and application thereof, but the method is directly used for water washing in a squeezing section and is limited by material concentration fluctuation and the state of used filter cloth, so that the effect of reducing sulfate radicals can be achieved, and the sulfate radicals cannot be stabilized in a narrow range. The production practicability is weaker, and equipment needs to be added.
Disclosure of Invention
The invention aims to solve the technical problems that the existing nano titanium dioxide for denitration with ultra-pure high specific surface area has high sulfate radical content, or the sulfur content can be controlled at a lower level, but the phenomena of large sulfate radical fluctuation, unstable production and the like exist, so that the nano titanium dioxide for denitration with ultra-pure high specific surface area and the preparation method thereof are provided.
The technical scheme of the invention is as follows: a preparation method of nanometer titanium dioxide for ultra-pure denitration with high specific surface area comprises the following steps:
(1): carrying out acidolysis, sedimentation, hot filtration, crystallization, ferrous separation and controlled filtration on the titanium concentrate to obtain a relatively pure titanyl sulfate solution;
(2): freezing and crystallizing the titanyl sulfate solution, controlling the iron-titanium ratio of the titanyl sulfate solution to be less than 0.2, and then carrying out solid-liquid separation to obtain a titanyl sulfate filter cake, wherein the freezing and crystallizing temperature is controlled to be below 6-8 ℃, and the environmental temperature is controlled to be below 20 ℃;
(3): concentrating the titanyl sulfate filter cake obtained in the previous step to TiO2The concentration is 155-165 g/l, and the larger agglomerated particle size is obtained by the micro-pressure hydrolysis of the added seed crystal, and the TiO is controlled2The agglomerate grain size is more than 2.0 and less than 2.2 of D50, and more than 3.0 and less than 4.0 of D90;
(4): the agglomerated titanyl sulfate is bleached by three-washing and one-bleaching, and the specific operation is that the one-time washing: mining
Washing for more than 4 hours by using a process water temperature of 55-65 ℃ and a molal leaf filter, controlling the iron content to be below 300ppm, and bleaching: adding concentrated sulfuric acid and aluminum powder into the agglomerated titanyl sulfate subjected to primary water washing at 65-70 ℃, and preserving heat for 3 hours, wherein the volume ratio of the agglomerated titanyl sulfate to the concentrated sulfuric acid is 1.8: 1.5, the mass of the added aluminum powder is 0.19-0.22 times of the total volume of the agglomerated titanyl sulfate, and Ti is controlled3+The content of the aluminum powder is 0.5-0.8%, the iron content after primary water washing is 200-500 ppm, if the iron content exceeds the standard, the aluminum powder needs to be added again, the mass of the added aluminum powder is 0.65 × 27/240+3+ the total volume of the agglomerated titanyl sulfate, and the dissolution reaction is carried out for 30 min; and (3) secondary water washing: controlling the volume flow of the agglomerated titanyl sulfate subjected to primary water washing to be 19 times of the volume of the agglomerated titanyl sulfate, heating to 65 ℃, preserving the temperature for 120min, and then adopting desalted waterWashing the filter leaves for more than 3 hours at the water temperature of 55-65 ℃ by using a molal leaf filter, and controlling the iron content to be below 25 ppm; and (3) washing for the third time: adding desalted water into the titanyl sulfate subjected to secondary water washing in a molar leaf filter, and pulping for more than 4 hours, wherein the water temperature is controlled to be 55-65 ℃, and the iron content is controlled to be below 30 ppm;
(5): heating the titanyl sulfate obtained in the step (4) to 50-65 ℃ by steam, adjusting the titanyl sulfate to 20-50 g/l, and controlling the dried finished product S to be less than or equal to 2000 ppm;
(6): pressing, calcining in a rotary kiln at 150-250 deg.C under BET of 200m2/g or more and water content of 5% or less, and grinding with stainless steel Raymond mill to obtain TiO2The content is more than or equal to 99 percent, and s is less than or equal to 2000 ppm.
In the scheme, the titanium concentrate in the step (1) comprises the following components in percentage by mass: TiO 22＞46%，Fe2O3＜7%，SiO2＜3%，S＜0.2%，P＜0.006%，MgO＜0.06%，Al2O3＜1.5%，MnO＜0.7%，V2O5Less than 0.1 percent, and the rest trace elements of Cu, Co, Ni, Cr and As are less than 0.02 percent.
The freezing crystallization in the step (2) in the scheme is carried out twice.
The nanometer titanium dioxide for the denitration with the ultra-pure high specific surface area is prepared by the method.
The invention has the advantages of simple process flow, low manufacturing cost, high product purity, low sulfate radical content and strong low-temperature poisoning resistance.
Detailed Description
The technical solution of the present invention is clearly and completely described below with reference to the following embodiments. It is to be understood that the described embodiments are merely exemplary of the invention, and not restrictive of the full scope of the invention. All other embodiments based on the embodiments in the present invention, without any inventive work, will be apparent to those skilled in the art from the following description.
The first embodiment is as follows:
(1): the mass fraction is as follows: TiO 22＞46%，Fe2O3＜7%，SiO2＜3%，S＜0.2%，P＜0.006%，MgO＜6.5%，Al2O3＜1.5%，MnO＜0.7%，V2O5Less than 0.1 percent, and the balance trace elements of Cu, Co, Ni, Cr and As are less than 0.02 percent, and then the titanium concentrate is subjected to acidolysis, sedimentation, hot filtration, crystallization, ferrous separation and controlled filtration to obtain a relatively pure titanyl sulfate solution;
(2): freezing and crystallizing the titanyl sulfate solution twice, controlling the iron-titanium ratio of the titanyl sulfate solution to be less than 0.2, and then carrying out solid-liquid separation to obtain a titanyl sulfate filter cake, wherein the freezing and crystallizing temperature is controlled to be below 6 ℃, and the environmental temperature is controlled to be below 20 ℃;
(3): concentrating the titanyl sulfate filter cake obtained in the previous step to TiO2At a concentration of 155g/l and by
Adding seed crystal to hydrolyze under micro pressure to obtain larger agglomerated particle size, and controlling TiO2The agglomerate grain size is more than 2.0 and less than 2.2 of D50, and more than 3.0 and less than 4.0 of D90;
(4): the agglomerated titanyl sulfate is bleached by three-washing and one-bleaching, and the specific operation is that the one-time washing: mining
Washing for more than 4 hours by using a process water temperature of 55-65 ℃ and a molal leaf filter, controlling the iron content to be below 300ppm, and bleaching: adding concentrated sulfuric acid and aluminum powder into the agglomerated titanyl sulfate subjected to primary water washing at 65-70 ℃, and preserving heat for 3 hours, wherein the volume ratio of the agglomerated titanyl sulfate to the concentrated sulfuric acid is 1.8: 1.5, the mass of the added aluminum powder is 0.22 times of the total volume of the agglomerated titanyl sulfate, and Ti is controlled3+The content of the aluminum powder is 0.5-0.8%, the iron content after primary water washing is 200-500 ppm, if the iron content exceeds the standard, the aluminum powder needs to be added again, the mass of the added aluminum powder is 0.65 × 27/240+3+ the total volume of the agglomerated titanyl sulfate, and the dissolution reaction is carried out for 30 min; and (3) secondary water washing: controlling the volume flow of the agglomerated titanyl sulfate subjected to primary water washing to be 19 times of the volume of the agglomerated titanyl sulfate, heating to 65 ℃, keeping the temperature for 120min, washing for more than 3 hours by using a desalted water at 65 ℃ and a molar leaf filter, and controlling the iron content to be below 50 ppm; and (3) washing for the third time: adding desalted water into the titanyl sulfate after secondary water washing in a molar leaf filter for pulping for more than 4 hours, controlling the water temperature at 65 ℃, and controlling ironThe content is below 30 ppm;
(5): heating the titanyl sulfate obtained in the step (4) to 50 ℃ by steam, and adjusting the titanyl sulfate to be 20 g/l;
(6): squeezing with a filter press, controlling solid content to 50-55%, calcining in a rotary kiln at 150 deg.C under controlling BET not less than 200m2/g and water content not more than 5%, pulverizing with stainless steel Raymond mill, and measuring TiO with X-ray fluorescence spectrometer2The content is more than or equal to 99 percent, and s =1798ppm of ultrapure high specific surface area denitration nanometer titanium dioxide.
Example two:
(1): the mass fraction is as follows: TiO 22＞46%，Fe2O3＜7%，SiO2＜3%，S＜0.2%，P＜0.006%，MgO＜6.5%，Al2O3＜1.5%，MnO＜0.7%，V2O5Less than 0.1 percent, and the balance trace elements of Cu, Co, Ni, Cr and As are less than 0.02 percent, and then the titanium concentrate is subjected to acidolysis, sedimentation, hot filtration, crystallization, ferrous separation and controlled filtration to obtain a relatively pure titanyl sulfate solution;
(2): freezing and crystallizing the titanyl sulfate solution twice, controlling the iron-titanium ratio of the titanyl sulfate solution to be less than 0.2, and then carrying out solid-liquid separation to obtain a titanyl sulfate filter cake, wherein the freezing and crystallizing temperature is controlled to be below 6 ℃, and the environmental temperature is controlled to be below 20 ℃;
(3): concentrating the titanyl sulfate filter cake obtained in the previous step to TiO2At a concentration of 158g/l and by
Adding seed crystal to hydrolyze under micro pressure to obtain larger agglomerated particle size, and controlling TiO2The agglomerate grain size is more than 2.0 and less than 2.2 of D50, and more than 3.0 and less than 4.0 of D90;
(4): the agglomerated titanyl sulfate is bleached by three washes and one bleaching, and the specific operation is as follows: primary water washing: mining
Washing for more than 4 hours by using a process water temperature of 55-65 ℃ and a molal leaf filter, controlling the iron content to be below 300ppm, and bleaching: adding concentrated sulfuric acid and aluminum powder into the agglomerated titanyl sulfate subjected to primary water washing at 65-70 ℃, and preserving heat for 3 hours, wherein the volume ratio of the agglomerated titanyl sulfate to the concentrated sulfuric acid is 1.8: 1.5, the mass of the added aluminum powder is 0.19 times of the total volume of the agglomerated titanyl sulfate, and Ti is controlled3+The content of the aluminum powder is 0.5-0.8%, the iron content after primary water washing is 200-500 ppm, if the iron content exceeds the standard, the aluminum powder needs to be added again, the mass of the added aluminum powder is 0.65 × 27/240+3+ the total volume of the agglomerated titanyl sulfate, and the dissolution reaction is carried out for 30 min; and (3) secondary water washing: controlling the volume flow of the agglomerated titanyl sulfate subjected to primary water washing to be 19 times of the volume of the agglomerated titanyl sulfate, heating to 65 ℃, keeping the temperature for 120min, washing for more than 3 hours by using a desalted water at 65 ℃ and a molar leaf filter, and controlling the iron content to be below 50 ppm; and (3) washing for the third time: adding desalted water into the titanyl sulfate subjected to secondary water washing in a molar leaf filter, and pulping for more than 4 hours, wherein the water temperature is controlled to be 55-65 ℃, and the iron content is controlled to be below 30 ppm;
(5): heating the titanyl sulfate obtained in the step (4) to 60 ℃ by steam, and adjusting 30 g/l of titanyl sulfate;
(6): pressing, calcining in rotary kiln at 200 deg.C under BET of 200m or more 2/g, pulverizing with stainless steel Raymond mill, and measuring TiO with X-ray fluorescence spectrometer2The content is more than or equal to 99 percent, and s =1650ppm of the product, namely the ultra-pure high specific surface area denitration nanometer titanium dioxide.
Example three:
(1): the mass fraction is as follows: TiO 22＞46%，Fe2O3＜7%，SiO2＜3%，S＜0.2%，P＜0.006%，MgO＜6.5%，Al2O3＜1.5%，MnO＜0.7%，V2O5Less than 0.1 percent, and the balance trace elements of Cu, Co, Ni, Cr and As are less than 0.02 percent, and then the titanium concentrate is subjected to acidolysis, sedimentation, hot filtration, crystallization, ferrous separation and controlled filtration to obtain a relatively pure titanyl sulfate solution;
(2): freezing and crystallizing the titanyl sulfate solution twice, controlling the iron-titanium ratio of the titanyl sulfate solution to be less than 0.2, and then carrying out solid-liquid separation to obtain a titanyl sulfate filter cake, wherein the freezing and crystallizing temperature is controlled to be below 7 ℃, and the environmental temperature is controlled to be below 20 ℃;
(3): concentrating the titanyl sulfate filter cake obtained in the previous step to TiO2At a concentration of 162g/l and by
Seed crystal is added to be hydrolyzed under the micro pressure to obtain larger agglomerated grain diameter,controlling TiO2The agglomerate grain size is more than 2.0 and less than 2.2 of D50, and more than 3.0 and less than 4.0 of D90;
(4): the agglomerated titanyl sulfate is bleached by three-washing and one-bleaching, and the specific operation is that the one-time washing: mining
Washing for more than 4 hours by using a process water temperature of 55-65 ℃ and a molal leaf filter, controlling the iron content to be below 300ppm, and bleaching: adding concentrated sulfuric acid and aluminum powder into the agglomerated titanyl sulfate subjected to primary water washing at 65-70 ℃, and preserving heat for 3 hours, wherein the volume ratio of the agglomerated titanyl sulfate to the concentrated sulfuric acid is 1.8: 1.5, the mass of the added aluminum powder is 0.20 times of the total volume of the agglomerated titanyl sulfate, and Ti is controlled3+The content of the aluminum powder is 0.5-0.8%, the iron content after primary water washing is 200-500 ppm, if the iron content exceeds the standard, the aluminum powder needs to be added again, the mass of the added aluminum powder is 0.65 × 27/240+3+ the total volume of the agglomerated titanyl sulfate, and the dissolution reaction is carried out for 30 min; and (3) secondary water washing: controlling the volume flow of the agglomerated titanyl sulfate subjected to primary water washing to be 19 times of the volume of the agglomerated titanyl sulfate, heating to 65 ℃, keeping the temperature for 120min, washing for more than 3 hours by using a desalted water at 65 ℃ and a molar leaf filter, and controlling the iron content to be below 50 ppm; and (3) washing for the third time: adding desalted water into the titanyl sulfate subjected to secondary water washing in a molar leaf filter, and pulping for more than 4 hours, wherein the water temperature is controlled at 60 ℃, and the iron content is controlled to be below 30 ppm;
(5): heating the titanyl sulfate obtained in the step (4) to 55 ℃ by steam, and adjusting 40 g/l of titanyl sulfate;
(6): pressing, calcining in rotary kiln at 210 deg.C and BET not less than 200m2/g, pulverizing, and measuring TiO by X-ray fluorescence spectrometer2The content is more than or equal to 99 percent, and S =1540ppm of the product, namely the ultra-pure high specific surface area denitration nanometer titanium dioxide.
Example four:
(1): the mass fraction is as follows: TiO 22＞46%，Fe2O3＜7%，SiO2＜3%，S＜0.2%，P＜0.006%，MgO＜6.5%，Al2O3＜1.5%，MnO＜0.7%，V2O5Less than 0.1 percent and the balance of trace elements of Cu, Co, Ni, Cr and As are less than 0.02 percent by acid treatmentDecomposing, settling, hot filtering, crystallizing, separating ferrous, controlling and filtering to obtain a relatively pure titanyl sulfate solution;
(2): freezing and crystallizing the titanyl sulfate solution twice, controlling the iron-titanium ratio of the titanyl sulfate solution to be less than 0.2, and then carrying out solid-liquid separation to obtain a titanyl sulfate filter cake, wherein the freezing and crystallizing temperature is controlled to be below 8 ℃, and the environmental temperature is controlled to be below 20 ℃;
(3): concentrating the titanyl sulfate filter cake obtained in the previous step to TiO2At a concentration of 165g/l and by
Adding seed crystal to hydrolyze under micro pressure to obtain larger agglomerated particle size, and controlling TiO2The agglomerate grain size is more than 2.0 and less than 2.2 of D50, and more than 3.0 and less than 4.0 of D90;
(4): the agglomerated titanyl sulfate is bleached by three-washing and one-bleaching, and the specific operation is that the one-time washing: mining
Washing for more than 4 hours by using a process water temperature of 55-65 ℃ and a molal leaf filter, controlling the iron content to be below 300ppm, and bleaching: adding concentrated sulfuric acid and aluminum powder into the agglomerated titanyl sulfate subjected to primary water washing at 65-70 ℃, and preserving heat for 3 hours, wherein the volume ratio of the agglomerated titanyl sulfate to the concentrated sulfuric acid is 1.8: 1.5, the mass of the added aluminum powder is 0.22 times of the total volume of the agglomerated titanyl sulfate, and Ti is controlled3+The content of the aluminum powder is 0.5-0.8%, the iron content after primary water washing is 200-500 ppm, if the iron content exceeds the standard, the aluminum powder needs to be added again, the mass of the added aluminum powder is 0.65 × 27/240+3+ the total volume of the agglomerated titanyl sulfate, and the dissolution reaction is carried out for 30 min; and (3) secondary water washing: controlling the volume flow of the agglomerated titanyl sulfate subjected to primary water washing to be 19 times of the volume of the agglomerated titanyl sulfate, heating to 65 ℃, keeping the temperature for 120min, washing for more than 3 hours by using a desalted water at 65 ℃ and a molar leaf filter, and controlling the iron content to be below 50 ppm; and (3) washing for the third time: adding desalted water into the titanyl sulfate subjected to secondary water washing in a molar leaf filter, and pulping for more than 4 hours, wherein the water temperature is controlled at 65 ℃, and the iron content is controlled to be below 30 ppm;
(5): heating the titanyl sulfate obtained in the step (4) to 65 ℃ by steam, adjusting 50g/l of titanyl sulfate, and controlling the dried finished product S to be less than or equal to 2000 ppm;
(6) squeezing and then calcining in rotary kilnCalcining at 180 deg.C and BET of not less than 200m2/g, grinding with stainless steel Raymond mill, and measuring TiO with X-ray fluorescence spectrometer2The content is more than or equal to 99 percent, and s =1430ppm of the product ultra-pure high specific surface area denitration nanometer titanium dioxide.
Compared with the sulfur content of the finished product of the Chinese invention patent CN107298460B which can be reduced to below 0.4%, the sulfur content can be controlled to be below 2000ppm by heating with steam before pressing, and the sulfur content is further reduced, which is unexpected for the technical personnel in the field, as is well known, the sulfur content can be controlled to be below 0.4%, but the breakthrough of the sulfur content to below 0.2% cannot be realized by the prior art, the minimum sulfur content can only be about 0.21%, the fluctuation range of the sulfur content is large and unstable, and the sulfur content is at least 0.21% and at most 0.35% according to several sets of comparative experimental data in the specific implementation mode part of the patent. The lowest sulfur content can be controlled to 1798ppm, 1650ppm, 1540ppm and 1430ppm, the fluctuation range of the sulfur content is narrow, and the product performance is stable. And this application utilizes former production line just can realize, need not to add equipment, and the low energy consumption of temperature is few.

Claims (4)

1. A preparation method of nanometer titanium dioxide for ultra-pure high specific surface area denitration is characterized by comprising the following steps: it comprises the following steps:
(1): carrying out acidolysis, sedimentation, hot filtration, crystallization, ferrous separation and controlled filtration on the titanium concentrate to obtain a relatively pure titanyl sulfate solution;
(2): freezing and crystallizing the titanyl sulfate solution, controlling the iron-titanium ratio of the titanyl sulfate solution to be less than 0.2, and then carrying out solid-liquid separation to obtain a titanyl sulfate filter cake, wherein the freezing and crystallizing temperature is controlled to be below 6-8 ℃, and the environmental temperature is controlled to be below 20 ℃;
(3): concentrating the titanyl sulfate filter cake obtained in the previous step to TiO2The concentration is 155-165 g/l, and the larger agglomerated particle size is obtained by the micro-pressure hydrolysis of the added seed crystal, and the TiO is controlled2The agglomerate grain size is more than 2.0 and less than 2.2 of D50, and more than 3.0 and less than 4.0 of D90;
(4): the agglomerated titanyl sulfate is bleached by three washes and one bleaching, and the concrete operation is carried outAs, one-time water washing: washing for more than 4 hours by adopting a process water temperature of 55-65 ℃ and a molal leaf filter, controlling the iron content to be below 300ppm, and bleaching: adding concentrated sulfuric acid and aluminum powder into the agglomerated titanyl sulfate subjected to primary water washing at 65-70 ℃, and preserving heat for 3 hours, wherein the volume ratio of the agglomerated titanyl sulfate to the concentrated sulfuric acid is 1.8: 1.5, the mass of the added aluminum powder is 0.19-0.22 times of the total volume of the agglomerated titanyl sulfate, and Ti is controlled3+The content of the aluminum powder is 0.5-0.8%, the iron content after primary water washing is 200-500 ppm, if the iron content exceeds the standard, the aluminum powder needs to be added again, the mass of the added aluminum powder is 0.65 × 27/240+3+ the total volume of the agglomerated titanyl sulfate, and the dissolution reaction is carried out for 30 min; and (3) secondary water washing: controlling the volume flow of the agglomerated titanyl sulfate subjected to primary water washing to be 19 times of the volume of the agglomerated titanyl sulfate, heating to 65 ℃, keeping the temperature for 120min, washing for more than 3 hours by using a desalted water at the temperature of 55-65 ℃ and a molar leaf filter, and controlling the iron content to be below 25 ppm; and (3) washing for the third time: adding desalted water into the titanyl sulfate subjected to secondary water washing in a molar leaf filter, and pulping for more than 4 hours, wherein the water temperature is controlled to be 55-65 ℃, and the iron content is controlled to be below 30 ppm;
(5): heating the titanyl sulfate obtained in the step (4) to 50-65 ℃ by steam, adjusting the titanyl sulfate to 20-50 g/l, and controlling the dried finished product S to be less than or equal to 2000 ppm;
(6): pressing, calcining in a rotary kiln at 150-250 deg.C under BET of 200m2/g or more and water content of 5% or less, and grinding with stainless steel Raymond mill to obtain TiO2The content is more than or equal to 99 percent, and s is less than or equal to 2000 ppm.
2. The preparation method of the ultrapure nano titanium dioxide with high specific surface area for denitration according to claim 1, which is characterized by comprising the following steps: the titanium concentrate in the step (1) comprises the following components in percentage by mass: TiO 22＞46%，Fe2O3＜7%，SiO2＜3%，S＜0.2%，P＜0.006%，MgO＜0.06%，Al2O3＜1.5%，MnO＜0.7%，V2O5Less than 0.1 percent, and the rest trace elements of Cu, Co, Ni, Cr and As are less than 0.02 percent.
3. The preparation method of the ultrapure nano titanium dioxide with high specific surface area for denitration according to claim 1, which is characterized by comprising the following steps: the freezing crystallization in the step (2) is carried out twice.
4. The nanometer titanium dioxide for the denitration of the ultrapure high specific surface area is characterized in that: the preparation method of the ultrapure high-specific surface area denitration nanometer titanium dioxide is characterized by being prepared by the preparation method of the ultrapure high-specific surface area denitration nanometer titanium dioxide of any one of claims 1 to 3.
CN202011208619.3A 2020-11-03 2020-11-03 Nanometer titanium dioxide for ultra-pure high-specific-surface-area denitration and preparation method thereof Pending CN112299475A (en)

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