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CN-121988276-A - Method for strengthening decomposition of waste SCR denitration catalyst and preparing arsenic-removing adsorbent

CN121988276ACN 121988276 ACN121988276 ACN 121988276ACN-121988276-A

Abstract

The invention discloses a method for strengthening decomposition of a waste SCR denitration catalyst and preparing an arsenic-removing adsorbent, which comprises the steps of (1) mixing waste SCR denitration catalyst powder with sodium hydroxide and a pore-forming agent, adding water, stirring to prepare uniform reaction slurry, (2) carrying out sodium treatment reaction on the reaction slurry at 120-350 ℃ to obtain sodium-modified clinker, (3) adding water into the sodium-modified clinker, carrying out water leaching treatment, carrying out solid-liquid separation and water washing to obtain a water immersion liquid and a porous intermediate, (4) mixing the porous intermediate with an acidic washing liquid, carrying out acid eluting sodium treatment, controlling the pH value of an acid washing end point to be 0.5-2.0, and carrying out solid-liquid separation to obtain sodium-containing acid liquid and a porous titanium-based adsorbent, wherein the porous titanium-based adsorbent is used for removing arsenic.

Inventors

  • CAO CAIFANG
  • LI JIAYU
  • XU ZHIFENG
  • HU WEIJIE
  • YANG JIAWEN
  • Gan Kaisong

Assignees

  • 江西理工大学

Dates

Publication Date
20260508
Application Date
20260202

Claims (7)

  1. 1. The method for strengthening decomposition of the waste SCR denitration catalyst and preparing the arsenic-removing adsorbent is characterized by comprising the following steps of: (1) Mixing waste SCR denitration catalyst powder, sodium hydroxide and a pore-forming agent in proportion, adding water according to a certain liquid-solid ratio, and stirring to prepare uniform reaction slurry, wherein the pore-forming agent comprises one or more of sodium nitrite, sodium nitrate and sodium chloride, and the molar ratio of the adding amount to the sodium hydroxide is 0.3-1.5; (2) Placing the reaction slurry obtained in the step (1) in a reaction vessel, and carrying out sodium treatment reaction at 120-350 ℃ under normal pressure, wherein the reaction time is 0.5-3 hours, so as to obtain sodium clinker; (3) Adding water into the sodium-modified clinker obtained in the step (2) according to a certain liquid-solid ratio, carrying out water leaching treatment at a certain temperature and for a certain time to leach vanadium, tungsten and molybdenum in the reaction intermediate into solution, and carrying out solid-liquid separation and water washing to obtain water leaching solution and a porous intermediate; (4) Mixing the porous intermediate obtained in the step (3) with an acidic washing solution, performing acid elution sodium treatment, controlling the pH value of an acid washing end point to be 0.5-2.0, and performing solid-liquid separation to obtain sodium-containing acid solution and a porous titanium-based adsorbent, wherein the porous titanium-based adsorbent is used for removing arsenic.
  2. 2. The method of claim 1, further comprising the step of (5) adding the porous titanium-based adsorbent obtained in the step (4) into an arsenic-containing solution to perform an arsenic removal reaction, wherein the molar ratio of titanium to arsenic is 1-2, the reaction temperature is controlled to be 60-100 ℃, the stirring reaction is carried out for 15-45 minutes, and the arsenic-removed liquid and the arsenic-carrying adsorbent are obtained after solid-liquid separation.
  3. 3. The method of claim 2, wherein the arsenic concentration of the arsenic-containing solution in step (5) is 3 to 45g/L by mass.
  4. 4. The method of claim 1, wherein the waste SCR denitration catalyst in the step (1) is one or two of a vanadium-titanium series plate type catalyst and a honeycomb type catalyst, and the chemical composition of the waste SCR denitration catalyst comprises, by mass, more than 60% of titanium dioxide, 0.3% -1% of vanadium pentoxide, and 1.5% -6% of the total amount of tungsten trioxide and molybdenum trioxide.
  5. 5. The method of claim 1, wherein the weight ratio of the added amount of sodium hydroxide to the waste SCR denitration catalyst powder in the step (1) is 0.4-1.0, and the liquid-solid ratio is 2-5, and the unit is L/kg.
  6. 6. The method of claim 1, wherein the liquid-solid ratio in the step (3) is 2-5, the unit is L/kg, the reaction temperature of the water immersion treatment is 60-100 ℃, and the reaction time is 20-90 minutes.
  7. 7. The method of claim 1, wherein the acidic wash solution in step (4) comprises one or more of nitric acid, sulfuric acid, and hydrochloric acid.

Description

Method for strengthening decomposition of waste SCR denitration catalyst and preparing arsenic-removing adsorbent Technical Field The invention belongs to the field of recycling of solid wastes, and relates to a high-value utilization method for efficiently extracting vanadium, tungsten and molybdenum from a waste SCR catalyst and converting a titanium dioxide carrier into an arsenic-removing adsorbent. Background With the increasing environmental protection requirements, vanadium-tungsten (molybdenum) titanium SCR catalysts have been widely used for industrial flue gas denitration. The catalyst takes TiO 2 as a carrier, V 2O5 as an active ingredient, and WO 3 (and/or MoO 3) as an auxiliary agent and a stabilizer. After failure, the waste is classified as dangerous waste because of containing pentavalent vanadium, and if the waste is not properly disposed, the waste of valuable elements such as vanadium, tungsten, molybdenum, titanium and the like can be caused as well as the harm to the environment and the health of human bodies. Therefore, the harmless and full-component recycling of the material is of great significance. Currently, methods for recovering valuable metals from spent SCR catalysts mainly include pyrogenic, wet and combined processes. Hydrometallurgy is the mainstream because of lower energy consumption and higher metal recovery rate, and processes such as 'alkali fusion-water leaching' or 'direct acid leaching/alkali leaching' are commonly used. Although the alkali fusion-water leaching method can realize the separation of vanadium, tungsten, molybdenum and titanium carriers, the process has high energy consumption and strong corrosion to equipment, the subsequent solution system is complex, the separation and purification steps are complex, and the wastewater treatment cost is high. Although the direct acid leaching method can leach vanadium, tungsten, molybdenum and titanium simultaneously, the coexistence of a plurality of metal ions causes great separation difficulty, and the direct acid leaching method generally needs to rely on subsequent procedures such as solvent extraction or ion exchange and the like, and has the problems of long flow, high reagent consumption, easy generation of acid wastewater and the like. In contrast, the single alkaline leaching method can avoid high-temperature melting, but the leaching efficiency of tungsten and molybdenum is often not high, and meanwhile, the common technical problem of mutual separation of vanadium, tungsten and molybdenum is also faced. In addition, in the existing recovery process, the titanium component is produced in the form of leaching slag, and is usually only used as low-value titanium-rich material or subjected to landfill treatment, so that high-value utilization cannot be realized. In fact, the titanium-based material after certain treatment has the characteristics of large specific surface area, multiple surface active sites and the like, and has the potential of being used as an adsorbent in the field of wastewater treatment. However, how to directly convert titanium slag into a high-performance adsorbent while efficiently recovering valuable elements through a simple and efficient process is an important way for realizing high-value utilization of the waste SCR denitration catalyst carrier. Disclosure of Invention The invention aims to provide a method for strengthening decomposition of a waste SCR denitration catalyst and preparing an arsenic removal adsorbent, and aims to solve the problems of low metal leaching rate, complicated separation steps and failure in high-value utilization of titanium slag in the prior art. In order to achieve the above purpose, the invention provides a method for strengthening decomposition and preparing an arsenic removal adsorbent by using a waste SCR denitration catalyst, which comprises the following steps: (1) Mixing waste SCR denitration catalyst powder, sodium hydroxide and a pore-forming agent in proportion, adding water according to a certain liquid-solid ratio, and stirring to prepare uniform reaction slurry, wherein the pore-forming agent comprises one or more of sodium nitrite, sodium nitrate and sodium chloride, and the molar ratio of the adding amount to the sodium hydroxide is 0.3-1.5; (2) Placing the reaction slurry obtained in the step (1) in a reaction vessel, and carrying out sodium treatment reaction at 120-350 ℃ under normal pressure, wherein the reaction time is 0.5-3 hours, so as to obtain sodium clinker; (3) Adding water into the sodium-modified clinker obtained in the step (2) according to a certain liquid-solid ratio, carrying out water leaching treatment at a certain temperature and for a certain time to leach vanadium, tungsten and molybdenum in the reaction intermediate into solution, and carrying out solid-liquid separation and water washing to obtain water leaching solution and a porous intermediate; (4) Mixing the porous intermediate obtained in the step (3) with