CN113005288B - Titanium-containing pellet containing waste SCR catalyst and preparation method thereof - Google Patents
Titanium-containing pellet containing waste SCR catalyst and preparation method thereof Download PDFInfo
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
- C22B1/00—Preliminary treatment of ores or scrap
- C22B1/14—Agglomerating; Briquetting; Binding; Granulating
- C22B1/24—Binding; Briquetting ; Granulating
- C22B1/242—Binding; Briquetting ; Granulating with binders
- C22B1/243—Binding; Briquetting ; Granulating with binders inorganic
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21B—MANUFACTURE OF IRON OR STEEL
- C21B5/00—Making pig-iron in the blast furnace
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
- C22B1/00—Preliminary treatment of ores or scrap
- C22B1/005—Preliminary treatment of scrap
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
- C22B1/00—Preliminary treatment of ores or scrap
- C22B1/02—Roasting processes
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
- C22B1/00—Preliminary treatment of ores or scrap
- C22B1/14—Agglomerating; Briquetting; Binding; Granulating
- C22B1/24—Binding; Briquetting ; Granulating
- C22B1/2406—Binding; Briquetting ; Granulating pelletizing
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Abstract
The application relates to a titanium-containing pellet containing a waste SCR catalyst and a preparation method thereof, and belongs to the technical field of waste catalyst recovery, wherein the pellet comprises an iron-containing raw material, catalyst powder and a liquid-phase auxiliary agent, the catalyst powder is waste SCR catalyst powder, and the catalyst powder contains titanium oxide with the titanium oxide content of not less than 60%; the liquid phase auxiliary can form a low melting point substance with a melting point lower than 1230 ℃. The pellets not only effectively recover the waste SCR catalyst and realize the volume reduction, harmless and recycling treatment of the waste SCR catalyst, but also have excellent metallurgical properties by utilizing the bonding effect generated after the waste SCR catalyst powder is added, and finally the pellets with good performance indexes such as green pellet falling and compression strength, bursting temperature, compression strength after roasting and the like are produced.
Description
Technical Field
The application relates to the technical field of waste catalyst recovery, in particular to a titanium-containing pellet containing a waste SCR catalyst and a preparation method thereof.
Background
The titanium-containing pellets are raw materials for blast furnace protection, vanadium titano-magnetite is adopted in the production of the conventional titanium-containing pellets, and a large amount of binders are often required to be added in the pelletizing process due to poor pelletizing performance of the vanadium titano-magnetite, so that the production cost is high, but the pellet quality is still poor.
Meanwhile, the waste SCR denitration catalyst is taken as a dangerous solid waste, if the waste SCR denitration catalyst is randomly piled or improperly disposed, the waste SCR denitration catalyst is very likely to cause serious harm to the natural environment and human health, and meanwhile, the waste of resources is also caused. The current policy has strict treatment requirements on the waste SCR catalyst, and the recovery treatment mode in the prior art mainly comprises solidification/stabilization treatment and chemical treatment recovery aiming at the recovery treatment of the waste SCR denitration catalyst, wherein the solidification/stabilization treatment means can solve the current placement problem of the waste catalyst, but has hidden pollution hazards to the environment in the long term; the chemical treatment recovery method is easy to produce pollution waste liquid in the implementation process, and has complex flow and high cost. Therefore, a suitable solution is urgently required from the technical and economical viewpoints, and the harmless and resource efficient utilization treatment of the waste SCR denitration catalyst is realized. Through patent search, the technical proposal of the waste SCR flue gas denitration catalyst metallurgical sintering treatment method (application number: CN 201610280554.0) is as follows: crushing and grinding the waste catalyst to obtain powder, adding the powder into a sintering mixture according to a certain proportion, granulating, and finally fixing the waste catalyst in a sintering ore for sintering; for the technical scheme, the applicant carries out a reproduction test on a sintering cup, and discovers that the waste catalyst is directly added into sintering production, so that the metallurgical performance of the sintering ore is greatly negatively influenced, and the quality index of the sintering ore cannot meet the production requirement. Therefore, when seeking to treat spent catalyst using metallurgical production processes, it is not straightforward to add spent catalyst to the production process for treatment.
By analyzing the composition of the spent SCR catalyst,it was found that the main component was TiO 2 And the waste SCR catalyst has the characteristics of large specific surface area, strong water absorption, good static balling property and the like, if the waste SCR catalyst is added in the pellet production process to produce titanium-containing pellets, a feasible way is provided for the mass disposal of the waste SCR catalyst, and the problems that the conventional titanium-containing pellets are difficult to ball in the production process, the ore return rate is high and the like can be solved. The applicant carries out an trial experiment, the waste SCR catalyst with the mass fraction of 2.5% -10% is finely ground and then added into the pellet process, and the applicant surprisingly finds that the green pellet dropping strength, the compressive strength, the dry pellet and other performance indexes are obviously improved and the pellets are easier to pellet along with the addition of the waste SCR catalyst. But due to TiO 2 The introduction of the catalyst can cause insufficient consolidation in the pellets and crack, thereby reducing the strength of the pellets after roasting. Therefore, the waste SCR catalyst is treated by the pellet production process, the waste SCR catalyst can be considered to replace bentonite to be used as a binder, but the waste SCR catalyst cannot be simply added into pellet raw materials, the influence caused by adding the waste SCR catalyst is required to be fully considered, and the method adopts an optimized adding mode to realize harmless and recycling treatment of the waste SCR catalyst without influencing pellet production on the premise of fully analyzing a pellet strength reducing mechanism by combining theoretical analysis with practice.
Disclosure of Invention
Technical problem to be solved by the application
Aiming at the technical problems that the traditional titanium-containing pellet production process is difficult to be pelletized and the pellet performance is easy to be influenced, the titanium-containing pellet containing the waste SCR catalyst and the preparation method thereof are provided; the method provided by the application can obviously improve the properties of green pellet strength, compressive strength, bursting temperature, roasting pellet strength and the like, does not influence pellet production indexes, and provides a new method for harmless and resource efficient utilization of the waste SCR denitration catalyst.
Technical proposal
In order to achieve the above purpose, the technical scheme provided by the application is as follows:
the titanium-containing pellet of the waste SCR catalyst comprises an iron-containing raw material, catalyst powder and a liquid-phase auxiliary agent, wherein the catalyst powder is waste SCR catalyst powder, and the catalyst powder contains titanium oxide with the content of not less than 60%; the liquid phase auxiliary can form a low melting point substance with a melting point lower than 1230 ℃. The pellets not only effectively recover the waste SCR catalyst, but also have excellent metallurgical properties by utilizing the bonding effect generated after the waste SCR catalyst powder is added.
Preferably, the content of the low-melting-point substances in the pellets is not less than 5% of the dry material ratio of the pellets.
The application relates to a preparation method of titanium-containing pellets containing waste SCR (selective catalytic reduction) catalysts, which comprises the steps of taking iron-containing raw materials, waste SCR catalyst powder with titanium oxide content not less than 60% and liquid phase auxiliary agents as pelletizing raw materials, uniformly mixing, pelletizing to prepare green pellets, and drying, preheating and roasting the green pellets to form finished pellets; the reduction of the volume of the waste SCR catalyst, innocuity and recycling treatment are realized, and finally, the pellets with good performance indexes such as green pellet dropping and compressive strength, bursting temperature, roasting pellet compressive strength and the like are produced.
Preferably, the specific steps are as follows:
(1) Pretreatment of pelleting raw materials
Taking a waste SCR catalyst, removing fly ash of a plug in the waste SCR catalyst, and preparing separated waste SCR catalyst bodies into waste SCR catalyst powder;
taking liquid phase auxiliary raw materials to prepare liquid phase auxiliary powder;
(2) Pelletizing material mixing
Mixing an iron-containing raw material, waste SCR catalyst powder and liquid-phase auxiliary agent powder to dynamically contact the pelletizing raw materials to prepare a pelletizing material;
(3) Pelletizing the pelletizing material to obtain green pellets, and drying, preheating and roasting the green pellets to form finished pellets.
Preferably, in the step of pretreatment of the pelletization raw material, the iron-containing raw material, the waste catalyst and the liquid-phase auxiliary agent particles reach a mass percentage content of-0.074 mm particle size fraction of not less than 98%.
Preferably, the liquid phase auxiliary agent comprises sintered return ores and waste incineration fly ash.
Preferably, in the sintered return ores, the calcium ferrite content is not less than 30%; the CaO content in the waste incineration fly ash is not less than 30 percent.
Preferably, after the sintered return ores and the waste incineration fly ash are prepared into powder, the powder is uniformly mixed according to the proportion of 1:1-1.5, and the powder is roasted for 3-5 hours under the air atmosphere condition at 600-900 ℃.
Preferably, the iron-containing raw material comprises magnetite, and TFe in the magnetite is more than or equal to 60.00%.
Preferably, the dynamic contact is carried out between the pelletizing raw materials, and then the static contact is carried out; the dynamic contact time is 40-45min, and the static contact time is 15-20min.
In the above preparation process, the further preferred steps are as follows:
step one, raw material pretreatment
(1) Preparing a waste catalyst: taking a waste catalyst, removing impurities in the waste catalyst, and crushing and grinding the waste catalyst;
(2) Preparing a liquid phase auxiliary agent: taking sintered return ores, grinding the return ores into powder; taking waste incineration fly ash, washing the fly ash with water to remove Na, K, cl and the like in the fly ash, and drying the fly ash to prepare powder;
(3) Preparing a pelletizing raw material: weighing and proportioning the iron-containing raw materials and the waste catalyst, and the liquid phase auxiliary agent and other pelleting materials after roasting according to the weight percentage, sampling and measuring the water content, uniformly mixing according to the actual supplementary water content, loading the mixture into a wetting mill together with 5kg (plus or minus 0.1 kg) steel balls, and setting for 40-45min for wetting pretreatment. After finishing the wet grinding, the pellet size is sieved and used as a pelletizing raw material.
Step two, pelletizing test
Green pellet preparation was accomplished using a disc pelletizer. Each batch of pelletization material is 3kg (+ -0.1 kg), and the pelletization time is about 20min. Adding the treated pelletizing raw material into a disc pelletizer to supplement water, pelletizing to produce a core with proper particle size, and continuously adding the pelletizing raw material into the disc pelletizer to supplement water to enable the pelletizing raw material to grow into pellets. Screening after pelletizing, and selecting qualified green pellets to detect the water content of the pellets and the green pellet performance (green pellet falling strength, compressive strength and bursting temperature).
Step three, green pellet treatment
And (5) taking part of green pellets for drying, and carrying out dry pellet strength test and preheating roasting test.
Preferably, the waste catalyst in the first step is a sintered SCR waste catalyst, and the titanium oxide content is more than or equal to 60.00%;
preferably, in the first step, the grain size of the screened return ores is 3-5mm, and the content of the granular calcium ferrite is more than or equal to 30%;
preferably, in the first step, the iron-containing raw material is magnetite-Zhang Zhuang mineral powder, and TFe is more than or equal to 60.00%;
preferably, after the sintered return ores and the fly ash in the liquid phase auxiliary agent are prepared into powder, uniformly mixing the powder according to the proportion of 1:1, and roasting the powder for 3 to 5 hours at 900 ℃ under the air atmosphere condition;
preferably, in the first step, the adding proportion of the waste catalyst accounts for 2.5-10% of the total mass of the iron-containing raw material, and the adding proportion of the waste catalyst and the liquid phase auxiliary agent is 1:1;
preferably, the iron-containing raw material, the waste catalyst and the liquid phase auxiliary agent particles in the first step reach the mass percentage content of the particle size fraction of-0.074 mm to be more than or equal to 98%;
preferably, the moisture of the pelletizing raw material in the step one is 7.5-8.0%;
preferably, the Zhang Zhuang mineral powder, the return ore and the incineration fly ash in the first step have the following components in a table;
table 1, zhuang Kuang main chemical composition/wt.%
Table 2 main chemical composition of return mine/wt.%
TABLE 2 incineration fly ash main chemical composition/wt.%
Preferably, in the second step, the main parameters of the disc pelletizer are as follows: diameter Φ=1000 mm, disk rotation speed 25-30r/min, inclination 45 ° (±1°);
preferably, the green ball prepared in the second step has water content of about 8.0-8.5%;
preferably, the green pellets prepared in the second step have a granularity of 12.5mm-15.0mm and are qualified green pellets;
preferably, in the third step, the drying system is that the blowing flow rate is 0.5-0.8m/s and the temperature is 280-300 ℃;
preferably, the preheating and roasting system adopted in the third step is as follows: preheating at 950 deg.C (+ -10 deg.C) for 15-20min; the roasting temperature is 1200 ℃ (+/-10 ℃) and the time is 20-25min.
Advantageous effects
Compared with the prior art, the application has the following advantages:
(1) The titanium-containing pellet of the waste SCR catalyst comprises an iron-containing raw material, catalyst powder and a liquid-phase auxiliary agent, wherein the catalyst powder is waste SCR catalyst powder, and the catalyst powder contains titanium oxide with the content of not less than 60%; the liquid phase auxiliary can form a low melting point substance with a melting point lower than 1230 ℃. The pellets not only effectively recover the waste SCR catalyst, but also have excellent metallurgical properties by utilizing the bonding effect generated after the waste SCR catalyst powder is added.
(2) According to the preparation method of the titanium-containing pellets containing the waste SCR catalyst, disclosed by the application, the waste catalyst generated by the SCR denitration process of an iron and steel enterprise is used for replacing bentonite as an additive and is mixed with the binder and the iron-containing raw material to be subjected to pelleting treatment, so that the problem that the waste catalyst is difficult to recycle can be effectively solved, the gangue component content in the pellets is reduced, and compared with the common titanium-containing pellets, the iron grade is higher. The waste SCR catalyst has the characteristics of large specific surface area, strong water absorption, good static balling performance and the like, is a good substitute for bentonite, and finally produces pellets with good performance indexes such as green pellet dropping and compressive strength, bursting temperature, roasting pellet compressive strength and the like, thereby realizing the volume reduction, harmless and recycling treatment of the waste SCR catalyst.
(3) According to the preparation method of the titanium-containing pellets containing the waste SCR catalyst, the low-melting-point liquid phase auxiliary agent prepared by adding substances such as sintered return ores and incineration fly ash of garbage factories into the pellets, wherein the low-melting-point substances form a liquid phase in the pellet roasting process, and the liquid phase is solidified in the condensing process to solidify the pellets, so that the problem that TiO in the waste catalyst is caused in the process of producing the titanium-containing pellets is effectively solved 2 The introduction of the liquid phase auxiliary agent causes insufficient consolidation in the pellet and cracks, so that the strength of the pellet after roasting is reduced, and the mechanical property of the pellet is improved.
(4) According to the titanium-containing pellet containing the waste SCR catalyst, the liquid-phase auxiliary agent is added into the pellet, so that TiO in the waste catalyst is effectively avoided 2 The problem of low pellet strength is caused; meanwhile, tiO contained in the spent catalyst 2 The method has a good furnace protection effect on a blast furnace hearth, in addition, V, W elements in the waste catalyst are reduced into simple substances to enter molten iron, V and W elements belong to beneficial elements in a steelmaking process, and steel quality can be greatly improved after the V and W elements are remained in the molten steel, so that the volume reduction, harmlessness and recycling treatment and utilization of the waste SCR catalyst are realized.
(5) Aiming at the problems of complex process, high production cost, large influence on pellet quality and the like of the existing technology of replacing bentonite with an organic binder or an inorganic binder, the application provides a preparation method of a titanium-containing pellet containing a waste SCR catalyst, which uses a material with large production amount and low recycling rate of the waste SCR catalyst as a pelletizing raw material, effectively solves the problems of reduced taste and quality of the pellet added with bentonite, has reasonable technology and obvious economic benefit, and has wider application prospect.
(6) The preparation method of the titanium-containing pellets containing the waste SCR catalyst, disclosed by the application, utilizes the pellet process to cooperatively treat the waste incineration fly ash, and has important practical significance in promoting the harmonious development of cities and steel plants, building green developed city steel plants and the like.
Drawings
FIG. 1 is a flow chart of the preparation method of the present application.
Detailed Description
For the purpose of making the objects, technical solutions and advantages of the embodiments of the present application more clear, the technical solutions of the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present application, and it is apparent that the described embodiments are some embodiments of the present application, but not all embodiments of the present application; moreover, the embodiments are not independent, and can be combined with each other as required, so that a better effect is achieved. All other embodiments, which can be made by those skilled in the art based on the embodiments of the application without making any inventive effort, are intended to be within the scope of the application.
The titanium-containing pellet of the waste SCR catalyst comprises an iron-containing raw material, catalyst powder and a liquid-phase auxiliary agent, wherein the catalyst powder is waste SCR catalyst powder, and the catalyst powder contains titanium oxide with the content of not less than 60%; the liquid phase auxiliary can form a low melting point substance with a melting point lower than 1230 ℃. The pellets not only effectively recover the waste SCR catalyst, but also have excellent metallurgical properties by utilizing the bonding effect generated after the waste SCR catalyst powder is added; the content of low-melting-point substances in the pellets is not less than 5% of the dry material ratio of the pellets.
The application relates to a preparation method of titanium-containing pellets containing waste SCR (selective catalytic reduction) catalysts, which comprises the steps of taking iron-containing raw materials, waste SCR catalyst powder with titanium oxide content not less than 60% and liquid phase auxiliary agents as pelletizing raw materials, uniformly mixing, pelletizing to prepare green pellets, and drying, preheating and roasting the green pellets to form finished pellets; the reduction of the volume of the waste SCR catalyst, innocuity and recycling treatment are realized, and finally, the pellets with good performance indexes such as green pellet dropping and compressive strength, bursting temperature, roasting pellet compressive strength and the like are produced.
Preferably, the specific steps are as follows:
(1) Pretreatment of pelleting raw materials
Taking a waste SCR catalyst, removing fly ash of a plug in the waste SCR catalyst, and preparing separated waste SCR catalyst bodies into waste SCR catalyst powder; the iron-containing raw material, the waste catalyst and the liquid phase auxiliary agent particles reach the mass percentage content of-0.074 mm particle size fraction of not less than 98%.
Taking liquid phase auxiliary raw materials to prepare liquid phase auxiliary powder; the liquid phase auxiliary agent comprises sintered return ores and waste incineration fly ash, wherein the content of calcium ferrite in the sintered return ores is not less than 30%; the CaO content in the waste incineration fly ash is not less than 30%, in addition, after the sintered return ores and the waste incineration fly ash are made into powder, the powder is uniformly mixed according to the proportion of 1:1-1.5, and the powder is roasted for 3-5 hours under the air atmosphere condition at 600-900 ℃.
(2) Pelletizing material mixing
Mixing an iron-containing raw material, waste SCR catalyst powder and liquid-phase auxiliary agent powder to dynamically contact the pelletizing raw materials to prepare a pelletizing material; the iron-containing raw material comprises magnetite, and TFe in the magnetite is more than or equal to 60.00%; carrying out dynamic contact and then static contact on the pelletizing raw materials; the dynamic contact time is 40-45min, and the static contact time is 15-20min.
(3) Pelletizing the pelletizing material to obtain green pellets, and drying, preheating and roasting the green pellets to form finished pellets.
Example 1
The application provides a preparation method of titanium-containing pellets containing waste SCR (selective catalytic reduction) catalysts, which can properly solve the technical problems that the existing waste SCR catalysts are large in production amount and difficult to recycle, the traditional titanium-containing pellets are difficult to be pelletized in the production process, and the pellet performance is poor. The pellet ore produced by the method can meet various performance indexes of the pellet ore required by the blast furnace, and a new treatment method can be provided for the harmless and recycling efficient utilization of the waste SCR denitration catalyst.
The specific experimental steps of the application are as follows:
step one: pretreatment of raw materials
(1) Preparing a waste catalyst: taking a waste SCR catalyst, pretreating to remove the fly ash of a plug in the waste catalyst, and then crushing and grinding to obtain catalyst powder of-200 meshes;
(2) Preparing a liquid phase auxiliary agent: firstly, taking sintered return ores, screening particles with the granularity of 3-5mm, and grinding the particles into powder with the granularity of-200 meshes. Secondly, the waste incineration fly ash is taken, washed firstly, na, K, cl and other ions in the fly ash are removed, and dried to prepare-200 mesh powder. Finally, uniformly mixing the sintered return ore powder and the incineration fly ash powder according to the mass ratio of 1:1, and roasting for 3 hours at 900 ℃ under the air atmosphere condition to obtain a low-melting-point substance;
(3) Preparing a pelletizing raw material: weighing and proportioning Zhang Zhuang mineral powder, waste SCR catalyst, liquid phase auxiliary agent and other pelletizing materials according to mass percentage, controlling the water content to be about 7.5-8%, uniformly mixing, loading the mixture and 5kg (plus or minus 0.1 kg) steel balls into a moistening mill, setting for 40-45min for moistening and grinding pretreatment, namely dynamic contact, carrying out moistening and grinding pretreatment, and standing the mixture, namely static contact time is 15-20min.
Step two, pelletizing test
The green pellet preparation is completed by a disc pelletizer, and the main parameters of the disc pelletizer are as follows: diameter Φ=1000 mm, disk rotation speed 25-30r/min, inclination 45 ° (±1°). Each batch of pelletization material is 3kg (+ -0.1 kg), and the pelletization time is about 20min. Adding the treated pelletizing raw material into a disc pelletizer to supplement water to produce a core with proper particle size, and continuously adding the pelletizing material into the disc pelletizer to supplement water to enable the core to grow into pellets, wherein the water content of the pellets is controlled to be 8-8.5%. Screening after pelletizing, and selecting qualified green pellets with the diameter of 12.5-15.0 mm for green pellet performance (green pellet falling strength, compressive strength and bursting temperature) detection.
Step three, green ball falling strength detection
12 green balls with similar sizes are selected, and each time one green ball is tested, the green balls freely fall from a height of 0.5m to a steel plate with the thickness of 10 mm. The falling test is repeated from 0 times until the green ball has cracks, namely the falling times. The average value was calculated as green falling strength.
Step four, green ball compressive strength detection
Green compressive strength measurements were performed on a green compressive strength measuring instrument (YHKC-2A type) according to ISO 4700 standard. 12 green balls with similar sizes are selected, and one green ball is tested at a time. The average value was calculated as green compressive strength.
Step five, detecting bursting temperature of green pellets
The green pellet burst temperature was measured using a dynamic assay. And randomly taking 50 qualified raw balls, loading the raw balls into a detection cup body, changing the air temperature of a bursting furnace from low temperature to high temperature, wherein the change gradient is 20 ℃, after the air temperature is stable, putting the cup body with the small balls into a blast heating furnace tube, heating air, flowing through the small balls, and penetrating through the bottom of the cup body, and performing bursting test on the raw balls. The cup body is placed for 5min. If the number of the green pellets burst is 2, the corresponding temperature is the green pellet burst temperature of the test. One group of experimental balls is tested for 3 times, and an average value of the burst temperatures of three times is taken as a detection index.
Step six, drying the green pellets
Putting the qualified green pellets into a 300 ℃ blast drying furnace for drying, wherein the blast flow rate is 0.5-0.8m/s, the temperature is 280-300 ℃, and the blast time is 5-15 min; the number of green pellets per drying was 100, in this case the blowing flow rate was 0.6m/s, the temperature was 300℃and the blowing time was 8min.
Step seven, roasting the pellets
The pellet roasting is carried out in a vertical tube furnace, the roasting temperature is 1280 ℃, and the roasting time is 15min.
Step eight, detecting the compressive strength of the roasting ball
The compression strength of the baked pellets was measured on a pellet compression strength tester (model WDW-QT-10) according to ISO 4700-1996. And selecting 12 roasting balls with similar sizes, testing one roasting ball at a time, and calculating an average value as the compression strength of the pellets.
In the embodiment, the added waste catalyst pellets consist of Zhang Zhuang mineral powder, SCR waste catalyst and liquid phase auxiliary agent, and the mass percentages of the pellet materials are shown in table 1. And then adding the pelletization material into a disc pelletizer to supplement water to produce the pellets, detecting the green pellet performance (green pellet falling strength, green pellet compressive strength and bursting temperature) after pelletization, measuring the compressive strength of the pellets after roasting, and recording experimental results as shown in table 2.
Table 1 balling raw material ratio,%
What is necessary to say is: the iron ore powder adopted in the added dead catalyst pellets is Zhang Zhuangkuang, and the iron ore powder comprises the following components in percentage by mass: TFe:65.75%, feO:26.5%, siO 2 ：6.75％，Al 2 O 3 :0.84%, caO:0.30%, mgO:0.48%, P:0.014%, S:0.054% and the balance of unavoidable impurities; the liquid phase auxiliary agent adopted by the application is obtained by uniformly mixing and roasting sintered return ores and incineration fly ash according to the mass ratio of 1:1, wherein the sintered return ores comprise the following components in percentage by mass: fe (Fe) 2 O 3 ：77.11％,SiO 2 ：5.18％,Al 2 O 3 :2.18%, caO:10.07%, mgO:2.40 percent, S is 0.08 percent, and the rest is unavoidable impurities; wherein the incineration fly ash comprises the following components in percentage by mass: TFe:1.34%, caO:40.8%, siO 2 ：6.13％，Al 2 O 3 :1.01%, mgO:1.89%, S4.76%, cl:10.19%, LOI:27.59, the balance being unavoidable impurities; the waste catalyst is waste generated in a flue gas SCR denitration system of a coal-fired power plant, and comprises the following components in percentage by mass: tiO (titanium dioxide) 2 ：87.27％，WO 3 ：4.66％，SiO 2 ：3.64％，CaO：1.32％，Al 2 O 3 ：0.87％，V 2 O 5 :0.52%, sx:0.43%, P:0.07%, na:0.09%, K:0.07% and the balance of unavoidable impurities.
Comparative example 1
The comparative example was used as a reference experiment, and the pellet preparation process of the comparative example was the same as that of example 1, except that: bentonite is added into the pellets to be used as a pellet binder, and no waste catalyst and liquid phase auxiliary agent are added. The dry material of the mixture comprises the following components in percentage by mass: zhang Zhuang magnetite: 98%, bentonite: 2%, adding water into a disc pelletizer to supplement water for producing pellets, detecting the green pellet performance (green pellet falling strength, compressive strength and bursting temperature) after pelletizing, measuring the compressive strength of the baked pellets, and recording experimental results as shown in table 2.
Comparative example 2
The pellet preparation process of this comparative example was the same as in example 1, except that: the waste SCR catalyst is added into the pellets to be used as a pellet binder, and no liquid phase auxiliary agent is added. The dry material of the mixture comprises the following components in percentage by mass: zhang Zhuang magnetite: 95%, spent catalyst: 5.0 percent of water is added into a disc pelletizer to supplement water to produce pellets, green pellet performance (green pellet falling strength, compressive strength and bursting temperature) is detected after pelletizing is completed, and the compressive strength of the roasted pellets is measured, and experimental results are recorded as shown in table 2.
Table 2 pellet performance test
By comparative analysis of green pellet properties and fired pellet compressive strengths of example 1, comparative example 1 and comparative example 2 in table 2, the following conclusions can be drawn:
(1) Experiments of the embodiment 1 and the comparative example 1 show that the waste SCR catalyst is used as a binder, and the low-melting-point liquid phase auxiliary agent prepared from materials such as sintered return ores, incineration fly ash of garbage factories and the like is added into the pelletizing raw material to carry out pellet production, so that the pellet performance is greatly improved, the average falling strength of green pellets and the average compressive strength of the green pellets are obviously improved, the burst temperature of the pellets is also improved, the production requirement is met, and the waste catalyst can be used as the binder in the pellet production process.
(2) Experiments of comparative examples 1 and 2 show that the liquid phase auxiliary agent is not added, the dead catalyst is directly added into the pelleting raw material as a binder for pellet production, the average dropping strength and the average compressive strength index of the obtained green pellets are obviously superior to those of the standard experiment, but the compressive strength of the pellets after roasting is greatly reduced from 3553N/P in the standard period to 2017N/P. The main reason is that after the bentonite is replaced by the waste catalyst, the liquid phase quantity in the pellet roasting process is reduced, and the part which is originally bonded by the liquid phase cannot be bonded effectively, so that the strength of the pellets after roasting is reduced.
(3) Experiments of the embodiment 1, the comparative example 1 and the comparative example 2 show that the waste catalyst replaces bentonite to be used as a binder for pelletizing, the performance of the prepared green pellets can meet the standard experiment requirement, the production requirement is met, and meanwhile, a proper amount of liquid phase can be formed in the pellet roasting process by adding the liquid phase auxiliary agent, so that the pellets are effectively bonded, and the strength of the pellets after roasting is improved. Therefore, it can be seen that the waste catalyst cannot be simply used as a binder to replace bentonite to be added into pellet production, a pellet consolidation mechanism is required to be combined, a liquid phase auxiliary agent is reasonably added, and the influence of the addition of the waste catalyst on the strength after roasting is eliminated, so that the waste catalyst is effectively recycled in the pellet production process. The titanium-containing pellets produced simultaneously are used in the blast furnace protection period, and the recycling utilization of solid hazardous wastes such as waste catalysts, waste incineration fly ash and the like is realized.
The application uses the waste catalyst to replace bentonite as the binder for pelletizing, and simultaneously adds the liquid phase auxiliary agent, thus being capable of producing titanium-containing pellets meeting the blast furnace ironmaking requirement, the produced pellets have controllable titanium content and stable structure, and can be used for smelting at the initial stage of new blast furnace production or at the final stage of blast furnace age, wherein TiO is used for the production of the new blast furnace 2 The components can effectively protect the hearth of the blast furnace and prolong the service life of the blast furnace; meanwhile, the strong reducing atmosphere of the blast furnace can reduce V, W elements in the waste catalyst into simple substances to enter molten iron, and V and W elements belong to beneficial elements in the steelmaking process, and the steel quality can be greatly improved after the V and W elements are left in the molten steel; in addition, the fly ash generated by the incineration of the garbage is reasonably utilized, so that the reduction of the volume, the harmlessness and the recycling treatment and utilization of the waste SCR catalyst and the fly ash of the incineration of the garbage are realized.
The embodiment solves the problem of TiO in the waste catalyst 2 The problem of the reduction of the pellet strength caused by the introduction of the catalyst is found out by analyzing the characteristics of components in the spent catalyst and the physicochemical reaction of the components in the high-temperature roasting process 2 The pellet roasting process belongs to a non-reactant phase, and the inclusion in the pellet can influence the grain morphology in the pellet recrystallization process to prevent the grain growthAnd large, resulting in poor strength of the pellets after firing. In the embodiment, the sintered return ores and the waste incineration fly ash are subjected to pre-reaction treatment, the generated low-melting-point liquid phase auxiliary agent is added into the pelletizing raw material for pellet production, and the added sintered return ores are usually rich in 30-40% of Fe 2 O 3 Phase, according to the theory of calcium ferrite generation, starting from 400 ℃, fe 2 O 3 Reacts with CaO to form calcium ferrite (wherein the reaction product is CaO.Fe 2 O 3 Starting to generate 2 CaO.Fe at 500 DEG C 2 O 3 Generated at 400 ℃), the temperature is increased, and the reaction rate is greatly accelerated, so the liquid phase auxiliary agent is roasted for 3 hours at 900 ℃ in the embodiment, and Fe in the sintered return ore is utilized 2 O 3 Fully reacts with CaO in fly ash to form calcium ferrite, the melting point of the calcium ferrite phase is low (1216 ℃), and the calcium ferrite phase can form liquid phase at the roasting temperature of pellets to be filled between grains oxidized by magnetite, thereby playing a role of connecting the grains and eliminating TiO 2 Negative impact on pellet strength.
Example 2
The basic procedure of the method for producing titanium-containing pellets using the waste SCR catalyst as a binder in this example is the same as that of example 1, except that: the proportion of the waste catalyst in the waste catalyst pellets in the embodiment is 2.5% of the total mass of the iron-containing raw material, and the proportion of the liquid phase auxiliary agent is 2.5% of the total mass of the iron-containing raw material. After uniform mixing, adding water into a disc pelletizer to supplement water to produce pellets, detecting the green pellet performance (green pellet falling strength, compressive strength and bursting temperature) after pelletizing, measuring the compressive strength of the baked pellets, and recording experimental results as shown in table 3.
Example 3
The basic procedure of the method for producing titanium-containing pellets using the waste SCR catalyst as a binder in this example is the same as that of example 1, except that: the proportion of the waste catalyst in the waste catalyst pellets in the embodiment is 7.5 percent of the total mass of the iron-containing raw materials, the proportion of the liquid phase auxiliary agent is 7.5 percent of the total mass of the iron-containing raw materials, the mixture is added into a disc pelletizer after uniform mixing to supplement water to produce pellets, the green pellet performance (green pellet falling strength, compressive strength and bursting temperature) is detected after pelletizing is completed, the compressive strength of the roasted pellets is measured, and the experimental result record is shown in table 3.
Example 4
The basic procedure of the method for producing titanium-containing pellets using the waste SCR catalyst as a binder in this example is the same as that of example 1, except that: the proportion of the waste catalyst in the waste catalyst pellets in the embodiment is 10 percent of the total mass percentage of the iron-containing raw materials, the proportion of the liquid phase auxiliary agent is 10 percent of the total mass percentage of the iron-containing raw materials, the mixture is added into a disc pelletizer after uniform mixing to supplement water to produce pellets, green pellet performance (green pellet falling strength, compressive strength and bursting temperature) is detected after pelletizing is completed, the compressive strength of the roasted pellets is measured, and experimental results are recorded as shown in table 3.
Example 5
The basic procedure of the method for producing titanium-containing pellets using the waste SCR catalyst as a binder in this example is the same as that of example 1, except that: the proportion of the waste catalyst in the waste catalyst pellets in the embodiment is 12.5 percent of the total mass of the iron-containing raw materials, the proportion of the liquid phase auxiliary agent is 12.5 percent of the total mass of the iron-containing raw materials, the mixture is added into a disc pelletizer after uniform mixing to supplement water to produce pellets, the green pellet performance (green pellet falling strength, compressive strength and bursting temperature) is detected after pelletizing is completed, the compressive strength of the roasted pellets is measured, and the experimental result record is shown in table 3.
Table 3 pellet performance test
By comparing and analyzing the green pellet performance and the compressive strength of the pellets prepared by adding the waste catalyst and the liquid phase auxiliary agent in the table 3 after roasting, the following conclusion can be obtained:
(1) When the addition proportion of the waste catalyst is 2.5% to replace bentonite, the dropping strength and the compressive strength of the prepared green pellets are lower than those of the standard experimental pellets, and the strength of the roasted pellets is also lower than that of the standard experimental pellets, so that when the waste catalyst is used to replace bentonite to be bonded as pellets, the addition proportion is required to be more than 2.5%.
(2) When the adding proportion of the waste catalyst is 12.5%, the performance of the prepared green pellet is better than that of a standard experimental pellet, but the strength of the pellet after roasting is obviously reduced, so that the proportion of the proper waste catalyst to replace bentonite as a pellet binder is 5-10%.
The application has been described in detail hereinabove with reference to specific exemplary embodiments thereof. It will be understood that various modifications and changes may be made without departing from the scope of the application as defined by the appended claims. The detailed description and drawings are to be regarded in an illustrative rather than a restrictive sense, and if any such modifications and variations are desired to be included within the scope of the application described herein. Furthermore, the background art is intended to illustrate the state of the art and the meaning of the development and is not intended to limit the application or the field of application of the application.
Claims (7)
1. The titanium-containing pellet of the waste SCR catalyst is characterized by comprising an iron-containing raw material, catalyst powder and a liquid-phase auxiliary agent, wherein the catalyst powder is waste SCR catalyst powder, and the catalyst powder contains titanium oxide with the titanium oxide content of not less than 60%; the liquid phase auxiliary agent can form a low-melting-point substance, and the melting point of the liquid phase auxiliary agent is lower than 1230 ℃; specifically, the liquid phase auxiliary agent comprises sintered return ores and waste incineration fly ash, wherein the content of calcium ferrite in the sintered return ores is not less than 30%, and the content of CaO in the waste incineration fly ash is not less than 30%; the sintered return ores and the waste incineration fly ash are prepared into powder, uniformly mixed according to the proportion of 1:1-1.5, and then baked for 3-5 hours under the air atmosphere condition at 600-900 ℃.
2. The titanium-containing pellet of claim 1, wherein the low melting point material content of the pellet is not less than 5% of the pellet dry matter ratio.
3. A preparation method of titanium-containing pellets containing waste SCR catalyst is characterized in that iron-containing raw materials, waste SCR catalyst powder with titanium oxide content not less than 60% and liquid phase auxiliary agents are used as pelletizing raw materials, pelletizing is carried out after uniform mixing to prepare green pellets, and the green pellets are dried, preheated and baked to form finished pellets; the liquid phase auxiliary agent comprises sintered return ores and waste incineration fly ash, wherein the content of calcium ferrite in the sintered return ores is not less than 30%, and the content of CaO in the waste incineration fly ash is not less than 30%; the sintered return ores and the waste incineration fly ash are prepared into powder, uniformly mixed according to the proportion of 1:1-1.5, and then baked for 3-5 hours under the air atmosphere condition at 600-900 ℃.
4. The method for preparing the titanium-containing pellets of the waste SCR catalyst according to claim 3, which is characterized by comprising the following specific steps:
(1) Pretreatment of pelleting raw materials
Taking a waste SCR catalyst, removing fly ash of a plug in the waste SCR catalyst, and preparing separated waste SCR catalyst bodies into waste SCR catalyst powder;
taking liquid phase auxiliary raw materials to prepare liquid phase auxiliary powder;
(2) Pelletizing material mixing
Mixing an iron-containing raw material, waste SCR catalyst powder and liquid-phase auxiliary agent powder to dynamically contact the pelletizing raw materials to prepare a pelletizing material;
(3) Pelletizing the pelletizing material to obtain green pellets, and drying, preheating and roasting the green pellets to form finished pellets.
5. The method for preparing titanium-containing pellets of a waste SCR catalyst according to claim 4, wherein in the step of pretreating the pelletization raw material, the iron-containing raw material, the waste catalyst and the liquid-phase auxiliary agent particles reach a fraction of-0.074 mm by mass of not less than 98%.
6. The method for preparing titanium-containing pellets of waste SCR catalyst according to claim 4, wherein the iron-containing raw material comprises magnetite, and TFe in the magnetite is more than or equal to 60.00%.
7. The method for preparing titanium-containing pellets of a waste SCR catalyst according to claim 4, wherein the pelletizing raw materials are subjected to static contact after being subjected to dynamic contact; the dynamic contact time is 40-45min, and the static contact time is 15-20min.
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