CN115924967B - Method for preparing titanium dioxide by using titanium slag and titanium dioxide - Google Patents
Method for preparing titanium dioxide by using titanium slag and titanium dioxide Download PDFInfo
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Abstract
The invention relates to the field of solid waste treatment, and discloses a method for preparing titanium dioxide by utilizing titanium slag and titanium dioxide thereof. The method comprises the following steps: (1) leaching titanium slag in water, followed by filtration; (2) Filtering the residue obtained in the step (1) and containingMixing the solution with the oxidant for reaction, filtering, soaking the obtained filter residues in alkaline solution, and filtering; (3) Mixing the filter residue obtained in the step (2), an acid solution and optional low-molecular organic matters for reaction, taking out an upper solid-liquid mixture, centrifuging and drying; (4) And (3) mixing the material obtained in the step (3) with a roasting additive, and then calcining in an oxygen-containing atmosphere. The method can be used for preparing TiO in titanium slag 2 The method can be used for recycling the anatase titanium dioxide with higher activity, and has great application prospect.
Description
Technical Field
The invention relates to the field of solid waste treatment, in particular to a method for preparing titanium white powder by utilizing titanium slag and titanium white powder thereof.
Background
NH 3 The SCR denitration technology is the denitration method most applied in the field of coal burning at present, and the denitration catalyst is NH 3 The key point in SCR denitration technology. At present, the SCR denitration catalyst can be deactivated after long-time use, and the deactivated denitration catalyst can not be used any more, but is filled with a large amount of harmful elements, so that the SCR denitration catalyst has great harm to human beings and the environment, and therefore, the SCR denitration catalyst needs to be treated by adopting a proper method.
The sodium roasting method is an effective method which is relatively simple and widely used for recycling valuable metal elements in the waste denitration catalyst, and can separate two valuable metals of tungsten and vanadium in the waste denitration catalyst and obtain chemical products of vanadium and tungsten through subsequent treatment. However, in the sodium roasting method, a large amount of sodium salt and a waste denitration catalyst are generally adopted for mixed roasting, and most of titanium element in the waste denitration catalyst is converted from titanium dioxide into various salts such as sodium titanate while valuable metal vanadium and tungsten are separated, so that the titanium element in the waste denitration catalyst is difficult to recycle.
Although the titanium slag obtained by a sodium roasting method of the waste denitration catalyst is treated to obtain a titanium white product in the prior art at present, the treatment method is only aimed at titanium slag with low impurity content and high titanium dioxide content, and most of prepared rutile type titanium white which is low in activity and difficult to be used for preparing chemicals is low in subsequent application value, and the recycled titanium white is disordered in component, poor in quality and narrow in application range.
In addition, since the titanium slag obtained by the sodium roasting method contains a large amount of Na element, the titanium pigment used for preparing the denitration catalyst industrially has extremely strict requirements on the Na element content. And the titanium dioxide content in the titanium slag obtained by the waste denitration catalyst through the sodium roasting method is still higher, and the value of further recycling still exists.
Disclosure of Invention
The invention aims to solve the problems that titanium slag obtained by a sodium roasting method of a waste denitration catalyst in the prior art is difficult to recycle, and the recycled titanium white product is low in activity, poor in quality and the like, and provides a method for preparing titanium white by using titanium slag and titanium white thereof, wherein TiO in the titanium slag can be prepared by the method 2 The method can be used for recycling the anatase titanium dioxide with higher activity, and has great application prospect.
In order to achieve the above object, according to one aspect of the present invention, there is provided a method for preparing titanium pigment using titanium slag, the method comprising the steps of:
(1) Leaching titanium slag in water, and then filtering;
(2) Mixing the filter residue obtained in the step (1) with a solution containing an oxidant for reaction, filtering, soaking the obtained filter residue in an alkaline solution, and filtering;
(3) Mixing the filter residue obtained in the step (2), an acid solution and optional low-molecular organic matters for reaction, taking out an upper solid-liquid mixture, centrifuging and drying;
(4) Mixing the material obtained in the step (3) with a roasting additive, and calcining in an oxygen-containing atmosphere;
the titanium slag is obtained by a sodium roasting method through a waste denitration catalyst, and TiO (titanium dioxide) in the titanium slag 2 The content of (2) is more than or equal to 60wt%;
the concentration of the solute in the acidic solution is 0.02-1mol/L;
the molecular weight of the low molecular organic matters is less than or equal to 600.
Preferably, the oxidant is hydrogen peroxide or persulfate.
Preferably, the mass concentration of the hydrogen peroxide is 5-30%;
preferably, the concentration of the persulfate is 10-200g/L.
Preferably, in step (2), the reaction conditions include: the temperature is 60-80 ℃ and the time is 6-24h.
Preferably, in step (2), the liquid to solid ratio at the time of the reaction is 5-10ml:1g.
Preferably, the concentration of the alkaline substance in the alkaline solution is 0.05-3g/L.
Preferably, in step (2), the soaking conditions include: the temperature is 60-110deg.C, and the time is 60-120min.
Preferably, in step (3), the reaction conditions include: the temperature is 60-90deg.C, and the time is 60-120min.
Preferably, the roasting additive is one or more selected from ammonium bicarbonate, coal slime and carbon powder.
Preferably, the conditions of the calcination include: the temperature is 600-750 ℃ and the time is 0.5-4h.
Preferably, the weight ratio of the material obtained in the step (3) to the amount of the roasting additive is 1:0.05-0.25.
The second aspect of the invention provides titanium dioxide prepared by the method.
The method of the invention can recycle the titanium slag obtained by recycling the waste denitration catalyst through a sodium roasting method and prepare a high-activity titanium dioxide product, the method comprises the steps of firstly placing the titanium slag into an oxidizing solution for reaction, then soaking the titanium slag into an alkaline solution to remove heavy metal elements and As elements attached to the surface of the titanium slag, and then reacting the filter residue after removing the heavy metal elements and the As elements in an acidic solution, the inventor of the invention surprisingly discovers that in the reaction system, the reaction system can be obviously layered by regulating the concentration of the acidic solution, and the titanium dioxide obtained by separating, collecting and calcining the solid-liquid mixture on the upper layer has regular appearance, and the TiO in the titanium dioxide 2 The titanium dioxide has high purity, excellent water dispersibility and better quality. The titanium dioxide prepared by the method has larger specific surface area and higher pore volume, completely meets the requirements of the standard HG/T4525-2013 titanium dioxide for catalysts, and has great application prospect.
Drawings
FIG. 1 is an XRD spectrum of the titanium pigment recovered in examples 1-3;
FIG. 2 is an SEM image of the titanium pigment recovered in example 1.
Detailed Description
The following describes specific embodiments of the present invention in detail with reference to the drawings. It should be understood that the detailed description and specific examples, while indicating and illustrating the invention, are not intended to limit the invention.
The endpoints and any values of the ranges disclosed herein are not limited to the precise range or value, and are understood to encompass values approaching those ranges or values. For numerical ranges, one or more new numerical ranges may be found between the endpoints of each range, between the endpoint of each range and the individual point value, and between the individual point value, in combination with each other, and are to be considered as specifically disclosed herein.
In the invention, the sodium roasting method is to mix the waste denitration catalyst with sodium salt and then calcine the mixture at high temperature, so that insoluble metal oxide in the waste denitration catalyst is changed into sodium salt corresponding to the insoluble metal oxide, and the subsequent leaching and collection are facilitated.
In the invention, the residual amount of the heavy metal element refers to the sum of the contents of the metal element Ni, pb, cr, zn and Cu in the finally recovered titanium white powder.
The invention provides a method for preparing titanium dioxide by utilizing titanium slag, which comprises the following steps:
(1) Leaching titanium slag in water, and then filtering;
(2) Mixing the filter residue obtained in the step (1) with a solution containing an oxidant for reaction, filtering, soaking the obtained filter residue in an alkaline solution, and filtering;
(3) Mixing the filter residue obtained in the step (2), an acid solution and optional low-molecular organic matters for reaction, taking out an upper solid-liquid mixture, centrifuging and drying;
(4) And (3) mixing the material obtained in the step (3) with a roasting additive, and then calcining in an oxygen-containing atmosphere.
In the method of the invention, the waste denitration catalyst contains 60 to 85 weight percent of titanium dioxide and 1 to 6 weight percent of WO 3 And 0.05 to 1 wt.% of V 2 O 5 。
In the method of the present invention, the temperature of the sodium salt roasting method is controlled to be not less than 650 ℃, preferably 650 to 800 ℃, and the roasting time and the conditions other than the temperature of the sodium salt roasting method are not particularly limited.
In the method, the titanium slag is obtained by a sodium roasting method from a waste denitration catalyst, and the method can be used forTo remove TiO in the titanium slag 2 The titanium slag with lower content and higher impurity content is recycled, when the content of titanium dioxide in the titanium slag is only 60 weight percent, the titanium slag can be treated by adopting the method of the invention, and the TiO in the titanium slag 2 The content of (C) is not less than 60% by weight, preferably 65-80% by weight.
In the method, the titanium slag is leached in water, substances such as sodium tungstate and sodium vanadate contained in the titanium slag can be promoted to be leached in water, most of titanium element is reserved in filter residues to be extracted, and the filtered filtrate can be used for collecting tungsten element and vanadium element in the filtrate in a conventional mode. Specifically, the tungsten element and the vanadium element can be mobile phones in a mode of ion adsorption or precipitation by a salt solution.
In a specific embodiment, the leaching conditions in step (1) include: the temperature is 40-60 ℃ and the time is 6-12h.
In the method of the present invention, in step (2), before mixing the filter residue obtained in step (1) with the solution containing the oxidizing agent, the filter residue obtained in step (1) needs to be dried, and the dried filter residue is ball-milled, where the ball-milling conditions include: the rotating speed of ball milling is 240-320rpm, the ball milling time is more than or equal to 2 hours, and the particle size of the ball milled material is less than or equal to 100 meshes.
In a specific embodiment, in the step (2), the filter residue obtained in the step (1) is reacted in a solution containing an oxidant, and then the reacted filter residue is soaked in an alkaline solution to remove heavy metal elements (Ni, pb, cr, zn and Cu) and As elements attached to the surface of the titanium slag, wherein the heavy metal elements and the As elements are the main reasons for promoting the deactivation of a denitration catalyst, the requirements on the residual quantity of the heavy metal elements and the content of the As elements in the recovered titanium dioxide are strict, the residual quantity of the heavy metal elements is required to be lower than 5 mug/g, and the content of the As elements is required to be lower than 1 mug/g.
In a specific embodiment, the step (2) includes: mixing the filter residues obtained in the step (1) in a solution containing an oxidant for reaction, filtering after the reaction is finished, drying the filter residues obtained by filtering, soaking the dried filter residues in an alkaline solution, and filtering.
In the method of the invention, the oxidant is hydrogen peroxide or persulfate.
In particular embodiments, the persulfate may be sodium persulfate, potassium persulfate, or ammonium persulfate.
In the method, the mass concentration of the hydrogen peroxide is 5-30%, preferably 8-15%; the concentration of the persulfate is 10-200g/L, preferably 50-100g/L. Specifically, the mass concentration of the hydrogen peroxide can be 5%, 10%, 15%, 20%, 25% or 30%; the concentration of the persulfate may be 10g/L, 50g/L, 100g/L, 150g/L or 200g/L.
In a specific embodiment, in step (2), the reaction conditions include: the temperature is 60-80 ℃ and the time is 6-24h. Specifically, the temperature of the reaction may be 60 ℃, 65 ℃, 70 ℃, 75 ℃, or 80 ℃; the reaction time may be 6h, 10h, 12h, 15h, 20h or 24h.
In a specific embodiment, in step (2), the liquid to solid ratio at the time of the reaction is 5-10ml:1g, preferably 6-8ml:1g. Specifically, the liquid to solid ratio at the time of the reaction may be 5mL:1g, 6mL:1g, 7mL:1g, 8mL:1g, 9mL:1g, or 10mL:1g.
In a specific embodiment, the concentration of the alkaline substance in the alkaline solution is 0.05-3g/L, preferably 1-2.5g/L. Specifically, the concentration of the alkaline substance in the alkaline solution may be 1g/L, 2g/L or 2.5g/L.
In particular embodiments, the alkaline solution may be a NaOH solution, a KOH solution, or an aqueous ammonia solution.
In a specific embodiment, in step (2), the soaking conditions include: the temperature is 60-110deg.C, and the time is 60-120min. Specifically, the soaking temperature may be 60 ℃, 70 ℃, 80 ℃, 90 ℃, 100 ℃ or 110 ℃; the soaking time can be 60min, 70min, 80min, 90min, 100min, 110min or 120min.
In the method according to the invention, in step (3)The sodium titanate in the filter residue obtained in the step (2) is converted into titanic acid when the filter residue reacts with the acid solution, the inventor of the invention unexpectedly finds that under the combined action of the acid solution and the low-molecular organic matters in the reaction system in the step (3), a uniform solid-liquid mixture is formed in the reaction system by materials with complete structures and uniform particle sizes in the titanic acid, the solid-liquid mixture is left on the upper layer of the solution, a part with incomplete structures and complex components becomes a precipitate and is left on the bottom of the solution, obvious boundaries exist between the solid-liquid mixture on the upper layer and the precipitate on the bottom, then the solid-liquid mixture on the upper layer can be separated, and the titanium dioxide with regular morphology, uniform particle sizes and good water dispersibility is obtained by drying and calcining. In the reaction system of the step (3), the reason for delamination of the reaction system may be that the titanic acid with regular morphology and smaller particle size easily adsorbs H on the surface thereof in the acidic solution + And OH (OH) - The two ions increase the compatibility between substances and water, so that the upper-layer regular-morphology material and the lower-layer irregular-morphology material can be separated, then the upper-layer solid-liquid mixture is collected and calcined to obtain the regular-morphology anatase titanium dioxide, the band gap width of the anatase titanium dioxide is slightly larger than that of the rutile titanium dioxide, and photogenerated electrons and holes are not easy to be compounded on the surface, so that the anatase titanium dioxide has higher activity than the rutile titanium dioxide, and the subsequent application value is wider.
In the method, in order to separate and obtain the material with complete morphology and uniform particle size, it is necessary to control the concentration of the acidic material in the acidic solution in the step (3), when the concentration of the acidic material in the acidic solution is too high, the content of titanium dioxide in the titanium dioxide is too low, and when the concentration of the acidic material in the acidic solution is too low, the weight of the solid-liquid mixture without the upper layer in the reaction system in the step (3) is too low, so that the yield of the finally recovered titanium dioxide is too low.
In a preferred embodiment, the concentration of solute in the acidic solution is controlled to be 0.02-1mol/L, preferably 0.1-0.8mol/L. Specifically, the concentration of the solute in the acidic solution may be 0.1mol/L, 0.2mol/L, 0.3mol/L, 0.4mol/L, 0.5mol/L, 0.6mol/L, 0.7mol/L or 0.8mol/L.
In a specific embodiment, the acidic solution is selected from one of a hydrochloric acid solution, a sulfuric acid solution, or a nitric acid solution.
In the method of the present invention, the "low molecular organic matter" refers to an organic matter having a relatively low molecular mass, which can promote the reaction in the step (3), and the molecular weight of the low molecular organic matter is less than or equal to 600, preferably 50 to 300.
In a specific embodiment, a low molecular organic compound, which is preferably an aqueous solution, is selected, and the low molecular organic compound may be a low molecular alcohol compound, a low molecular carboxylic acid compound, or a low molecular aldehyde compound.
In more specific embodiments, the low molecular alcohol compound may be ethanol or ethylene glycol; the low molecular carboxylic acid compound can be acetic acid or sodium acetate; the low molecular aldehyde compound may be acetaldehyde.
In a specific embodiment, the liquid-solid ratio of the low molecular organic matter to the titanium slag is 0.2-3mL:1g, preferably 0.5-2mL:1g.
In the method of the present invention, in step (3), the reaction conditions include: the temperature is 60-90deg.C, and the time is 60-120min. Specifically, the temperature of the reaction may be 60 ℃, 70 ℃, 80 ℃, or 90 ℃; the reaction time may be 60min, 80min, 100min or 120min.
In a specific embodiment, in step (3), the filter residue obtained in step (2) is further dried before being reacted.
In the method of the invention, in the step (4), the titanic acid in the material obtained in the step (3) is heated to be TiO after being mixed with the roasting additive and being calcined in the oxygen-containing atmosphere 2 And (5) after the calcination is finished, obtaining the titanium dioxide product.
In a specific embodiment, the calcination additive may promote the calcination reaction, and the calcination additive is one or more selected from ammonium bicarbonate, coal slime and carbon powder.
In the method of the invention, the weight ratio of the material obtained in the step (3) to the amount of the roasting additive is 1:0.05-0.25, preferably 1:0.1-0.2. Specifically, the weight ratio of the material obtained in the step (3) to the amount of the roasting additive may be 1:0.05, 1:0.1, 1:0.15, 1:0.2 or 1:0.25.
In a specific embodiment, the oxygen-containing atmosphere is air or a mixture of oxygen and an inert gas.
In a specific embodiment, the mixed gas of oxygen and inert gas may be a mixed gas of oxygen and argon, and the content of the oxygen in the mixed gas of oxygen and inert gas may be 2-10% by volume.
In the method of the present invention, in step (4), the conditions of the calcination include: the temperature is 600-750deg.C, preferably 650-700deg.C, and the time is 0.5-4 hr, preferably 2-3.5 hr. Specifically, the temperature of the calcination may be 650 ℃, 660 ℃, 670 ℃, 680 ℃, 690 ℃, or 700 ℃; the calcination time may be 2h, 2.5h, 3h or 3.5h.
In the method, the step (4) further comprises the steps of carrying out wet ball milling on the calcined material, drying and sieving to obtain the titanium white powder product, wherein the condition of wet ball milling is not limited, and the operation is carried out according to the common condition in the prior art.
The invention also provides titanium dioxide prepared by the method.
In the invention, the titanium dioxide in the titanium dioxide is in an anatase type crystal form, the activity of the titanium dioxide is higher than that of rutile type titanium dioxide recovered by a waste denitration catalyst in the prior art, the D50 particle size of the titanium dioxide is smaller, and the prepared titanium dioxide is higher in quality and has higher commercial value and wider application prospect.
The invention also provides application of the titanium dioxide in preparation of a denitration catalyst.
In the present inventionIn the denitration catalyst, tiO is generally used 2 The titanium dioxide prepared by the method can be used as a raw material of the denitration catalyst, and the titanium slag recovered by a sodium roasting method from the waste denitration catalyst is treated to remove impurities which deactivate the denitration catalyst, and then the titanium dioxide with regular morphology and good water dispersibility is recovered by adopting a specific mode, wherein the performance of the titanium dioxide completely meets the standard of HG/T4525-2013 titanium dioxide for catalyst, can be well used as the denitration titanium dioxide, and has higher commercial value and wide application prospect.
The present invention will be described in detail by way of examples, but the scope of the present invention is not limited thereto.
In the following examples and comparative examples, the titanium slag was obtained from a waste denitration catalyst obtained by a sodium roasting method at a roasting temperature of 700 ℃ for 3 hours, and the waste denitration catalyst was obtained from a waste denitration catalyst of a coal-fired power plant, and the waste denitration catalyst contained 70wt% of titanium dioxide and 3wt% of WO 3 And 0.5wt% of V 2 O 5 。
TiO in the titanium slag described in examples 1-3 2 、WO 3 And V 2 O 5 The content of each metal element in the titanium slag is obtained through an ICP-OES test.
Example 1
(1) Leaching titanium slag in water at 40 ℃ for 4 hours, and then filtering to obtain filter residues;
(2) Drying the filter residue obtained in the step (1), ball-milling to below 200 meshes, and then placing in hydrogen peroxide solution (with the mass concentration of 10%) for reaction, wherein the reaction temperature is 80 ℃, the reaction time is 10 hours, and the liquid-solid ratio during the reaction is 7mL:1g; filtering after the reaction is finished, soaking the obtained filter residue in NaOH solution (the concentration of NaOH is 1 g/L), wherein the soaking temperature is 80 ℃, the soaking time is 60min, and filtering;
(3) Centrifugally drying the filter residue obtained in the step (2), and then mixing the filter residue with hydrochloric acid solution (the concentration of hydrochloric acid is 0.05 mol/L) for reaction, wherein the reaction temperature is 80 ℃, and the reaction time is 60min; after the reaction is finished, taking out the upper layer solid-liquid mixture, centrifuging for 3-4 times to obtain a solid material, and drying the solid material;
(4) Mixing the material obtained in the step (3) with a roasting additive ammonium bicarbonate according to the weight ratio of 1:0.1, and then calcining in air at the calcining temperature of 700 ℃ for 2 hours; carrying out wet ball milling on the calcined product after the calcination is finished, and then drying and sieving the calcined product with a 400-mesh sieve to obtain titanium dioxide;
wherein the titanium slag contains 76.85wt% of TiO 2 WO 3.47wt% 3 V at 0.78wt% 2 O 5 The content of As element in the titanium slag is 103 mug/g, and the content of heavy metal (Ni, pb, cr, zn and Cu) is 122 mug/g.
Example 2
(1) Leaching titanium slag in water at 40 ℃ for 4 hours, and then filtering to obtain filter residues;
(2) Drying the filter residue obtained in the step (1), ball-milling to below 200 meshes, and then placing in hydrogen peroxide solution (with the mass concentration of 10%) for reaction, wherein the reaction temperature is 70 ℃, the reaction time is 12 hours, and the liquid-solid ratio is 8mL:1g during the reaction; filtering after the reaction is finished, soaking the obtained filter residue in NaOH solution (the concentration of NaOH is 1.5 g/L) at 75 ℃ for 60min, and filtering;
(3) Centrifugally drying the filter residue obtained in the step (2), and then mixing the filter residue with hydrochloric acid solution (the concentration of hydrochloric acid is 1 mol/L) for reaction, wherein the reaction temperature is 80 ℃, and the reaction time is 70min; after the reaction is finished, taking out the upper layer solid-liquid mixture, centrifuging for 3-4 times to obtain a solid material, and drying the solid material;
(4) Mixing the material obtained in the step (3) with calcined additive coal slime according to the weight ratio of 1:0.15, and calcining in air at 680 ℃ for 3 hours; carrying out wet ball milling on the calcined product after the calcination is finished, and then drying and sieving the calcined product with a 400-mesh sieve to obtain titanium dioxide;
wherein the titanium slag contains 76.85wt% of TiO 2 WO 3.47wt% 3 V at 0.78wt% 2 O 5 The content of As element in the titanium slag is 103 mug/g, and the content of heavy metal (Ni, pb, cr, zn and Cu) is 122 mug/g.
Example 3
(1) Leaching titanium slag in water at 40 ℃ for 4 hours, and then filtering to obtain filter residues;
(2) Drying the filter residue obtained in the step (1), ball-milling to below 200 meshes, and then placing the filter residue in hydrogen peroxide solution (the mass concentration is 10%) and ethanol (the liquid-solid ratio of the ethanol to the titanium slag is 0.3:1 ml/g) for reaction, wherein the reaction temperature is 80 ℃, the reaction time is 10 hours, and the liquid-solid ratio in the reaction is 7mL:1g; filtering after the reaction is finished, soaking the obtained filter residue in NaOH solution (the concentration of NaOH is 1.5 g/L) at the temperature of 100 ℃ for 70min, and filtering;
(3) Centrifugally drying the filter residue obtained in the step (2), and then mixing the filter residue with hydrochloric acid solution (the concentration of hydrochloric acid is 0.05 mol/L) for reaction, wherein the reaction temperature is 90 ℃, and the reaction time is 80min; after the reaction is finished, taking out the upper layer solid-liquid mixture, centrifuging for 3-4 times to obtain a solid material, and drying the solid material;
(4) Mixing the material obtained in the step (3) with a roasting additive ammonium bicarbonate according to the weight ratio of 1:0.1, and then calcining in air at the calcining temperature of 700 ℃ for 2 hours; carrying out wet ball milling on the calcined product after the calcination is finished, and drying to obtain titanium dioxide;
wherein the titanium slag contains 76.85wt% of TiO 2 WO 3.47wt% 3 V at 0.78wt% 2 O 5 The content of As element in the titanium slag is 103 mug/g, and the content of heavy metal (Ni, pb, cr, zn and Cu) is 122 mug/g.
Comparative example 1
The process was carried out according to example 1, except that in step (2), the residue obtained in step (1) was not reacted in a hydrogen peroxide solution, and was immersed in a NaOH solution, and the subsequent treatment was continued after the immersion was completed.
Comparative example 2
The procedure was carried out as in example 1, except that in step (2), the residue obtained in step (1) was reacted in a hydrogen peroxide solution, and the residue obtained by filtration was directly subjected to the operation of step (3).
Comparative example 3
The procedure was carried out as in example 1, except that step (3) was not carried out, and the residue obtained in step (2) was dried and then subjected to step (4).
Comparative example 4
The procedure of example 1 was followed, except that no calcination additive was added in step (4).
Comparative example 5
The procedure of example 1 was followed, except that in step (3), the concentration of the hydrochloric acid solution was 0.01mol/L.
Comparative example 6
The procedure of example 1 was followed, except that in step (3), the concentration of the hydrochloric acid solution was 2.5mol/L.
Comparative example 7
Provides titanium dioxide purchased from the blue chemical industry Co., ltd, and the model is BA01.
Test case
Test example 1
XRD was used to test the crystal forms of the final titanium dioxide of examples 1-3, and the spectra are shown in FIG. 1. As can be seen from FIG. 1, the XRD patterns of the titanium dioxide recovered in examples 1-3 are identical to the standard PDF patterns of anatase titanium dioxide, which shows that the crystal form of titanium dioxide in the titanium dioxide recovered finally by the method of the invention is anatase. The crystal form of the titanium dioxide in the titanium dioxide finally recovered by the invention is different from that of the titanium dioxide recovered by the prior art, and the activity is higher.
Test example 2
The morphology of the titanium dioxide product obtained in example 1 was tested by SEM, and the morphology diagram of the titanium dioxide obtained in example 1 is shown in fig. 2. The graph shows that the titanium dioxide recovered by the method provided by the invention is regular in appearance and uniform in particle size.
Test example 3
The titanium white powders recovered in examples 1 to 3 and the products obtained in comparative examples 1 to 6 and the products described in comparative example 7 were tested for properties.
Specific surface area: testing was performed according to the method of Standard GB/T19587-2004, with the test results shown in Table 1;
pore volume: testing was performed according to the standard GB/T31590-2015 method, and the test results are shown in Table 1;
TiO 2 purity: testing TiO in titanium white powder and products by adopting X-ray fluorescence spectrum 2 And calculating the TiO content of the obtained titanium white powder 2 The purity is calculated by the following steps: tiO in the sample to be measured 2 The weight of the sample to be tested, and the test results are shown in Table 1;
the content of As element in the titanium dioxide: the ICP-OES test was performed, and the test results are shown in Table 1;
na element in titanium dioxide: the ICP-OES test was performed, and the test results are shown in Table 1;
residual amount of heavy metals (Ni, pb, cr, zn and Cu) in titanium dioxide: the ICP-OES test was performed, and the test results are shown in Table 1;
d50 particle size: the test was performed using a laser particle sizer, and the test results are shown in table 1;
burning decrement: the titanium white powder of examples 1-3 and the products of comparative examples 1-7 were placed in a muffle furnace at 600 ℃ and calcined for 5 hours, and the weight difference before and after the calcination was measured, and the results are shown in Table 1;
the dispersibility of titanium pigment in water was tested: the specific test method comprises the following steps: 200g of a sample to be measured is added into 1L of water, the sample is dispersed for 15min by adopting a high-speed dispersing machine, the rotating speed is 2000r/min, the dispersing time is 15min, then the sedimentation height of titanium dioxide particles in the solution is tested after the sample is kept stand for 50h, when the dispersibility of the titanium dioxide in the water is better, the particles which are settled after the titanium dioxide is kept stand are fewer, and the sedimentation height of the particles in the solution is smaller, and the result is shown in a table 1.
TABLE 1
As can be seen from the results in Table 1, the method of the invention can recycle the titanium slag obtained by the sodium roasting method of the waste denitration catalyst to obtain anatase type titanium dioxide with higher activity, the titanium dioxide meets the specification of the standard HG/T4525-2013 titanium dioxide for catalyst, and the finally obtained titanium dioxide still has excellent physical properties, large specific surface area, high pore volume and smaller D50 particle size, and can be better applied to the preparation of the denitration catalyst. In addition, the concentration of the acidic solution used in step (3) in comparative example 5 was low, resulting in no collection of the solid-liquid mixture of the upper layer, and thus no final titanium pigment product was obtained. Meanwhile, the content of heavy metal, as and Na in the titanium dioxide finally obtained by the invention is very low, and the titanium dioxide product has better quality and wider application.
The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited thereto. Within the scope of the technical idea of the invention, a number of simple variants of the technical solution of the invention are possible, including combinations of the individual technical features in any other suitable way, which simple variants and combinations should likewise be regarded as being disclosed by the invention, all falling within the scope of protection of the invention.
Claims (12)
1. The method for preparing the titanium dioxide by utilizing the titanium slag is characterized by comprising the following steps of:
(1) Leaching titanium slag in water, and then filtering;
(2) Mixing the filter residue obtained in the step (1) with a solution containing an oxidant for reaction, filtering, soaking the obtained filter residue in an alkaline solution, and filtering;
(3) Mixing the filter residue obtained in the step (2), the acid solution and the low-molecular organic matters for reaction, taking out an upper solid-liquid mixture, and then carrying out centrifugal drying;
(4) Mixing the material obtained in the step (3) with a roasting additive, and calcining in an oxygen-containing atmosphere;
the titanium slag is obtained by a sodium roasting method through a waste denitration catalyst, and TiO (titanium dioxide) in the titanium slag 2 The content of (2) is more than or equal to 60wt%;
the concentration of the solute in the acidic solution is 0.02-2mol/L;
the acidic solution is selected from hydrochloric acid solution, sulfuric acid solution or nitric acid solution;
the low molecular organic matter is selected from ethanol, ethylene glycol, acetic acid, sodium acetate or acetaldehyde;
the roasting additive is one or more than two selected from ammonium bicarbonate, coal slime and carbon powder.
2. The method for preparing titanium white powder by utilizing titanium slag according to claim 1, wherein the oxidant is hydrogen peroxide or persulfate.
3. The method for preparing titanium white powder by utilizing titanium slag according to claim 2, wherein the mass concentration of the hydrogen peroxide is 5-30%.
4. The method for preparing titanium pigment by using titanium slag according to claim 2, wherein the concentration of the persulfate is 10-200g/L.
5. The method for preparing titanium pigment by using titanium slag according to claim 1, wherein in the step (2), the reaction conditions include: the temperature is 60-80 ℃ and the time is 6-24h.
6. The method for producing titanium white powder by using titanium slag according to claim 1, wherein in the step (2), the liquid-solid ratio at the time of the reaction is 5-10ml:1g.
7. The method for preparing titanium white powder by using titanium slag according to claim 1, wherein the concentration of alkaline substances in the alkaline solution is 0.05-3g/L.
8. The method for preparing titanium white powder by using titanium slag according to claim 1, wherein in the step (2), the soaking conditions include: the temperature is 60-110deg.C, and the time is 60-120min.
9. The method for preparing titanium pigment using titanium slag as claimed in claim 1, wherein in the step (3), the reaction conditions include: the temperature is 60-90deg.C, and the time is 60-120min.
10. The method for preparing titanium white powder by using titanium slag according to claim 1, wherein the calcining conditions include: the temperature is 600-750 ℃ and the time is 0.5-4h.
11. The method for preparing titanium white powder by utilizing titanium slag according to claim 1, wherein the weight ratio of the material obtained in the step (3) to the amount of the roasting additive is 1:0.05-0.25.
12. A titanium white powder obtained by the method for producing titanium white powder using titanium slag as claimed in any one of claims 1 to 11.
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