CN-121976031-A - Method for recycling iron and aluminum in red mud based on step-by-step acid leaching

CN121976031ACN 121976031 ACN121976031 ACN 121976031ACN-121976031-A

Abstract

The invention belongs to the technical field of solid waste recycling, and discloses a recycling recovery method of iron and aluminum in red mud based on fractional acid leaching, which effectively solves the problems of complex process and high acid-base consumption existing in the current synergistic efficient separation and recovery of iron and aluminum in red mud. Comprises the steps of red mud pretreatment, waste sulfuric acid step-by-step iron leaching, waste hydrochloric acid leaching of aluminum, sodium carbonate precipitation recovery of iron, alkali dissolution separation, and pH adjustment of recovered aluminum. The method realizes the high-selectivity leaching of the iron and the aluminum by step acid leaching, reduces the cost by utilizing the industrial waste acid, realizes the high-purity separation and recovery of the iron and the aluminum by step precipitation, has simple process, high resource recovery rate and environmental protection, and is suitable for the large-scale recycling treatment of the red mud.

Inventors

ZHANG YAZHOU
XIAO FULAI
CUI MINGMING
ZOU YULAN

Assignees

山东新寰清科技发展有限公司

Dates

Publication Date: 20260505
Application Date: 20260126

Claims (6)

1. The method for recycling the iron and aluminum in the red mud based on the step-by-step acid leaching is characterized by comprising the following steps of: s1, crushing and grinding red mud to D90<100 mu m to obtain red mud powder; s2, mixing red mud powder and waste sulfuric acid according to a solid-liquid mass ratio of 1:4-6, stirring and reacting at 90+/-5 ℃, and carrying out solid-liquid separation to obtain primary leaching liquid and primary leaching residue; S3, mixing the primary leaching residue and the waste hydrochloric acid according to a solid-liquid mass ratio of 1:2-4, stirring and reacting at 85+/-5 ℃, and carrying out solid-liquid separation to obtain secondary leaching liquid and secondary leaching residue; s4, diluting the primary leaching solution, dropwise adding a sodium carbonate solution at 65 ℃ until the pH value is 3-3.2, and filtering after heat preservation and aging to obtain ferric hydroxide; S5, diluting the secondary leaching solution, adding excessive sodium hydroxide solution, reacting at 60-70 ℃, filtering to obtain sodium metaaluminate solution and iron-containing filter residues, and then adjusting the pH value of the sodium metaaluminate solution to 7-8 to obtain the aluminum hydroxide.
2. The method for recycling iron and aluminum in red mud based on fractional acid leaching according to claim 1, wherein the mass concentration of waste sulfuric acid is 22% -24%, and the mass concentration of waste hydrochloric acid is 32.5% -36.6%.
3. The method for recycling iron and aluminum in red mud based on step-by-step acid leaching according to claim 1, wherein the primary leaching residue and the secondary leaching residue are respectively washed to pH 6, and the washed secondary leaching residue is used for soil improvement or refractory materials.
4. The method for recycling iron and aluminum in red mud based on step-by-step acid leaching according to claim 3, wherein in the step S4, the liquid used for diluting the primary leaching solution is primary slag leaching washing liquid or in-system circulating filtrate, and in the step S5, the liquid used for diluting the secondary leaching solution is secondary slag leaching washing liquid.
5. The method for recycling iron and aluminum in red mud based on fractional acid leaching according to claim 1, wherein in step S5, dilute hydrochloric acid or carbon dioxide aeration is adopted to adjust the pH of sodium metaaluminate solution.
6. The method for recycling iron and aluminum in red mud based on fractional acid leaching according to claim 5, wherein the iron-containing filter residue obtained in the step S5 is combined with the ferric hydroxide obtained in the step S4 for uniform drying treatment, and a ferric hydroxide product is obtained.

Description

Method for recycling iron and aluminum in red mud based on step-by-step acid leaching Technical Field The invention belongs to the technical field of solid waste recycling, and particularly relates to a recycling method for iron and aluminum in red mud based on fractional acid leaching. Background The red mud is solid waste residue generated in the production process of alumina, has strong alkalinity, and contains a certain amount of valuable components such as iron, aluminum, titanium, sodium and the like. At present, red mud is mostly deposited, occupies land and has environmental risks. The existing red mud recycling technology comprises valuable metal extraction, building material preparation and the like, but the problems of low recovery rate, high energy consumption, secondary pollution and the like are generally existed. Particularly, the synergistic and efficient separation and recovery of iron and aluminum still have the defects of complex process, high acid and alkali consumption and the like. Therefore, the development of the red mud recycling process which has reasonable flow, low cost and can realize the selective extraction of iron and aluminum has important significance. Disclosure of Invention The invention aims to provide a recycling recovery method of iron and aluminum in red mud based on fractional acid leaching, which effectively solves the problems of complex process and high acid-base consumption existing in the current synergistic efficient separation and recovery of iron and aluminum in red mud. In order to solve the technical problems, the technical scheme adopted by the invention is that the recycling method of iron and aluminum in the red mud based on step-by-step acid leaching comprises the following steps of S1, crushing and grinding the red mud to D90<100 mu m to obtain red mud powder. S2, mixing the red mud powder with waste sulfuric acid according to a solid-liquid mass ratio of 1:4-6, stirring and reacting for 3.5 hours at 90+/-5 ℃, and carrying out solid-liquid separation to obtain primary leaching liquid and primary leaching slag. S3, mixing the primary leaching residue and the waste hydrochloric acid according to a solid-liquid mass ratio of 1:2-4, stirring and reacting for 3 hours at 85+/-5 ℃, and carrying out solid-liquid separation to obtain secondary leaching liquid and secondary leaching residue. S4, diluting the primary leaching solution, dropwise adding a sodium carbonate solution at 65 ℃ until the pH value is 3-3.2, and filtering after heat preservation and aging to obtain ferric hydroxide. S5, diluting the secondary leaching solution, adding excessive sodium hydroxide solution, reacting for 2 hours at 60-70 ℃, filtering to obtain sodium metaaluminate solution and iron-containing filter residues, and then adjusting the pH value of the sodium metaaluminate solution to 7-8 to obtain the aluminum hydroxide. Further, the mass concentration of the waste sulfuric acid is 22% -24%, and the mass concentration of the waste hydrochloric acid is 32.5% -36.6%. Further, the primary leaching residue and the secondary leaching residue are respectively washed to pH 6, and the washed secondary leaching residue is used for soil improvement or refractory materials. Further, in the step S4, the liquid used for diluting the primary leaching solution is primary slag leaching washing liquid or the circulating filtrate in the system, and in the step S5, the liquid used for diluting the secondary leaching solution is secondary slag leaching washing liquid. Further, in step S5, the pH of the sodium metaaluminate solution is adjusted by aeration with dilute hydrochloric acid or carbon dioxide. Further, the iron-containing filter residues obtained in the step S5 are combined into the ferric hydroxide obtained in the step S4 for uniform drying treatment, and thus a ferric hydroxide product is obtained. Compared with the prior art, the method has the beneficial technical effects that (1) the method realizes the high-selectivity leaching of the iron and the aluminum by fractional acid leaching, reduces the cost by utilizing industrial waste acid, realizes the high-purity separation and recovery of the iron and the aluminum by fractional precipitation, realizes the iron leaching rate of more than 92 percent and the aluminum leaching rate of more than 88 percent, and ensures that the purities of the obtained ferric hydroxide and aluminum hydroxide products are more than 95 percent. (2) The process water and the intermediate washing liquid are recycled, the waste water discharge is reduced, and the final red mud leaching residue can be used for soil improvement, refractory materials and the like, so that full-component utilization is realized. Drawings Fig. 1 is a schematic flow chart of the present invention. Detailed Description Example 1A portion of the chemical starting material used in this example was first described (1) waste hydrochloric acid, technical grade, at a mass concentration of ab