Method for separating zinc and iron from zinc leaching residues

Abstract

The invention discloses a method for separating zinc and iron from zinc leaching residues. The method comprises the following steps: firstly, mixing the zinc leaching residues with ammonium sulfate and an additive, then performing roasting to ensure that zinc ferrite and the like in the zinc leaching residues are changed into soluble zinc sulfate and insoluble ferric oxide; secondly, directly leaching out a roasted product by using a dilute sulfuric acid solution; and finally, introducing fume which is produced during roasting and mainly contains ammonia gas into a zinc leaching solution to perform deposition so as to produce zinc hydroxide and an ammonium sulfate solution, and concentrating and crystallizing the ammonium sulfate solution to prepare ammonium sulfate which is returned to the ammonium sulfate roasting process. The ammonium sulfate roasting process in the method can ensure that a zinc ferrite phase in the zinc leaching residues is changed into soluble zinc sulfate, the leaching rate of zinc is more than 97%, and the leaching rate of iron is lower than 2%, so that the separation of zinc and iron is effectively realized; the ammonia gas produced in the ammonium sulfate roasting process is directly used for depositing zinc from the leaching solution, and the regeneration of ammonium sulfate can be realized while a zinc hydroxide product is generated; the comprehensive recovery rate of zinc is more than 96%; the method can realize closed-loop circulation and is relatively environment-friendly.

Description

technical field

[0001] The invention relates to pyrometallurgy and hydrometallurgy processes in the field of metallurgy, in particular to a method for effectively separating zinc and iron in zinc leaching slag. Background technique

[0002] Zinc sulfide concentrate is boiled and roasted to produce zinc calcine, which is directly leached using dilute sulfuric acid solution as a solvent. The zinc existing in the zinc oxide phase is dissolved during the leaching process, and the remaining zinc is retained in the slag, which is often called zinc leaching slag. . The undissolved zinc content in the zinc leaching slag is generally about 20%. Since the contained zinc mainly exists in the form of zinc ferrite, it is difficult to leaching in the conventional dilute sulfuric acid leaching process. Therefore, reduction volatilization is usually used in industry. treatment process or hot acid leaching process.

[0003] The reduction and volatilization treatment process is to mix the z...

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