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CN-122010120-A - Method for extracting silicon dioxide from red mud

CN122010120ACN 122010120 ACN122010120 ACN 122010120ACN-122010120-A

Abstract

The invention relates to the technical field of recycling, in particular to a method for extracting silicon dioxide from red mud, which comprises the following steps of 1) calcining the original red mud to obtain calcined red mud, 2) leaching the calcined red mud with waste sulfuric acid to obtain primary acid leaching solution and primary acid leaching slag, 3) leaching the primary acid leaching slag with waste hydrochloric acid to obtain secondary acid leaching solution and secondary acid leaching slag, 4) carrying out neutralization precipitation treatment on the primary acid leaching solution and the secondary acid leaching solution by adopting sodium carbonate solution to obtain precipitate and CO 2 , 5) fully dissolving the secondary acid leaching slag by using sodium hydroxide solution, separating out solution, filling CO 2 into the solution, filtering, washing and drying the precipitate to obtain the silica. According to the method for extracting silicon dioxide from red mud, disclosed by the invention, through calcination pretreatment, the crystal water is removed, the aluminum-silicon symbiotic structure is weakened, the foaming problem of the red mud in the acid leaching process is effectively inhibited, the separation of iron, aluminum and silicon is promoted, and the purity of a subsequent silicon extracting product is improved.

Inventors

  • ZHANG YAZHOU
  • XIAO FULAI
  • ZOU YULAN
  • QIU MING
  • CUI MINGMING
  • CHEN WEI

Assignees

  • 烟台南山学院
  • 山东新寰清科技发展有限公司

Dates

Publication Date
20260512
Application Date
20260403

Claims (7)

  1. 1. A method for extracting silicon dioxide from red mud, which is characterized by comprising the following steps: 1) Red mud pretreatment Calcining the original red mud to obtain calcined red mud; 2) Primary acid leaching Waste sulfuric acid leaching is carried out on the calcined red mud obtained in the step 1), so as to obtain primary acid leaching liquid and primary acid leaching slag; 3) Secondary acid leaching Leaching the primary acid leaching slag obtained in the step 2) by waste hydrochloric acid to obtain secondary acid leaching liquid and secondary acid leaching slag; 4) Neutralizing the precipitated pickle liquor Neutralizing and precipitating the primary pickle liquor obtained in the step 2) and the secondary pickle liquor obtained in the step 3) by using sodium carbonate solution to obtain precipitate and CO 2 ; 5) Silicon extraction And (3) fully dissolving the secondary acid leaching slag obtained in the step (3) by using sodium hydroxide solution, separating out a solution, filling CO 2 obtained in the step (4) into the solution, filtering, washing and drying the precipitate to obtain the silicon dioxide product.
  2. 2. The method for extracting silicon dioxide from red mud according to claim 1, wherein in step 1), the raw red mud is ball-milled until the D90 is less than 100 μm, in step 2), the mass concentration of waste sulfuric acid is 22.9%, in step 3), the mass concentration of waste hydrochloric acid is 34.6%, in step 4), the concentration of sodium carbonate solution is 2.5mol/L, and in step 5), the mass fraction of sodium hydroxide solution is 33.25%.
  3. 3. The method for extracting silicon dioxide from red mud according to claim 2, wherein the calcination treatment in the step 1) is that ball-milled raw red mud is placed in a muffle furnace, calcined at 500-600 ℃ for 40-80 min, and cooled for later use.
  4. 4. The method for extracting silicon dioxide from red mud according to claim 2, wherein in the step 2), the weight ratio of calcined red mud to waste sulfuric acid is 1 (3-7), the leaching temperature is 85-95 ℃, and the leaching time is 3-4 h.
  5. 5. The method for extracting silicon dioxide from red mud according to claim 2, wherein in the step 3), the amount of waste hydrochloric acid is 2-4 times the weight of the calcined red mud obtained in the step 1), the leaching temperature is 85-95 ℃, and the leaching time is 2-4 hours.
  6. 6. The method for extracting silicon dioxide from red mud according to claim 2, wherein in the step 4), the neutralization precipitation treatment operation of the primary acid leaching solution or the secondary acid leaching solution is performed by diluting the acid leaching solution with water according to the mass ratio (1.5-2): 1, slowly dripping sodium carbonate solution at 65 ℃, adjusting the pH value to 7.0, maintaining the temperature to 60-70 ℃, slowly stirring and aging for 0.5-1 h, filtering, obtaining a filter cake which is iron-aluminum composite hydroxide precipitate, and allowing the filtrate to enter the subsequent sodium carbonate recovery or recycling process.
  7. 7. The method for extracting silicon dioxide from red mud according to claim 2, wherein in the step 5), the solid-liquid ratio of the sodium hydroxide solution to the secondary leaching slag is 1 (4-6), the dissolution temperature is 85-95 ℃, the dissolution time is 2-4 h, the temperature of the dissolution solution is 50-70 ℃ when CO 2 is filled, and the filling of CO 2 is stopped when the pH of the dissolution solution is 7.8-8.5.

Description

Method for extracting silicon dioxide from red mud Technical Field The invention relates to the technical field of resource utilization, in particular to a method for extracting silicon dioxide from red mud. Background The red mud is a large amount of industrial solid waste discharged in the alumina production process, and has the characteristics of strong alkalinity, complex components, large storage quantity and the like. The red mud generally contains a plurality of components such as Fe 2O3、Al2O3、SiO2、CaO、TiO2, wherein the content of silicon dioxide is generally 15-25%, and the red mud has potential recycling value. The existing red mud treatment technology is mainly focused on the recovery of metal components such as iron, aluminum and the like, and silicon dioxide usually exists in the form of inert residues and is difficult to further utilize. The conventional acid leaching method has the following defects that 1, residual alkaline substances in red mud are easy to react with acid in an acid leaching process to generate a large amount of gas and foam, so that the foaming of a system is serious, the reaction safety and the operation stability are influenced, 2, aluminum and silicon components in red mud are mostly in a symbiotic or wrapped state, aluminum and silicon are difficult to effectively separate under the conventional acid leaching condition, the aluminum leaching is insufficient, aluminum impurities are carried in silicon dioxide in tailings to influence the purity of the follow-up silicon, the silicon dioxide in the tailings after the acid leaching is stable in structure and low in activity, the direct utilization value is low, 3, high-purity chemicals or exogenous carbon dioxide are additionally introduced in part of the process, and the treatment cost is increased. Therefore, a process method capable of inhibiting acid leaching foaming, cooperatively utilizing industrial waste acid and reaction to generate carbon dioxide and realizing efficient recovery of silicon dioxide in red mud is developed, and the process method has important significance for reduction and recycling of the red mud. Disclosure of Invention In order to solve the problems, the invention provides a method for extracting silicon dioxide from red mud, which comprises the following steps: 1) Red mud pretreatment Calcining the original red mud to obtain calcined red mud; 2) Primary acid leaching Waste sulfuric acid leaching is carried out on the calcined red mud obtained in the step 1), so as to obtain primary acid leaching liquid and primary acid leaching slag; 3) Secondary acid leaching Leaching the primary acid leaching slag obtained in the step 2) by waste hydrochloric acid to obtain secondary acid leaching liquid and secondary acid leaching slag; 4) Neutralizing the precipitated pickle liquor Neutralizing and precipitating the primary pickle liquor obtained in the step 2) and the secondary pickle liquor obtained in the step 3) by using sodium carbonate solution to obtain precipitate and CO 2; 5) Silicon extraction And (3) fully dissolving the secondary acid leaching slag obtained in the step (3) by using sodium hydroxide solution, separating out a solution, filling CO 2 obtained in the step (4) into the solution, filtering, washing and drying the precipitate to obtain the silicon dioxide product. The main components and contents of the red mud raw materials adopted by the invention are ：Al2O3 22.9%、Fe2O3 21.83%、Na2O 10.77%、SiO2 17.02%、CaO 1.32%、TiO2 4.81%,, ball milling treatment is carried out before calcination, and granules with D90 less than 100 mu m are selected. The chemical preparation used in each step is specifically 22.9% of waste sulfuric acid, 34.6% of waste hydrochloric acid, 2.5mol/L of sodium carbonate solution and 33.25% of sodium hydroxide solution. Specifically, in the step 1), the ball-milled raw red mud is placed in a muffle furnace, calcined at 500-600 ℃ for 40-80 min, and cooled for standby. The calcination in the muffle furnace aims to decompose indissolvable carbonate (such as calcium carbonate, sodium carbonate and the like) and partial hydroxide in the red mud at high temperature, and simultaneously destroy the original compact structure of the red mud, so that the combination state of metal oxides such as aluminum, iron and the like and silicon dioxide in the red mud is changed, the intergrowth structure of aluminum and silicon is destroyed, the aluminum and silicon are separated, the leaching efficiency of metal ions in the subsequent acid leaching process is improved, the phenomenon that a large amount of foam is generated due to the reaction of carbonate and acid in the acid leaching process is reduced, volatile impurities such as organic matters and the like in the red mud can be removed by calcination, the physicochemical properties of the red mud are further optimized, and favorable conditions are created for the subsequent acid leaching and silicon leaching processes. Specifically, in