A method for selectively enriching scandium from Bayer process red mud

Abstract

The invention discloses a method for selectively enriching scandium from Bayer process red mud. The method is characterized in that the Bayer process red mud is used as a raw material, the red mud isfully wet by adding an appropriate amount of water, the red mud is sulphated by using concentrated sulfuric acid and is then calcined at a high temperature, the solid calcined product is mechanicallyactivated by grinding and is then subjected to four-stage water immersion and washing, so that a scandium-rich leaching solution, scandium-rich washing liquid and low-alkali iron-rich slag are obtained. The method enables most of scandium to be leached, but the leaching rates of impurity iron and aluminum are low, and silicon and titanium are not leached substantially, so that the formation of colloidal silicate in the leaching solution is avoided, and the selective absorption and extraction of the scandium in the subsequent leaching solution are facilitated; the generated sulfur dioxide and sulfur trioxide can be reused in the preparation of sulfuric acid, so that the production of a large amount of waste acid is avoided; the pH of the low-alkali iron-rich slag is close to neutral, and can be used in the industries such as iron making, adsorbents, ceramics, construction and the like, so that a new way is provided for the extraction of the scandium and the comprehensive utilization ofthe red mud.

Description

technical field [0001] The invention belongs to the technical field of solid waste comprehensive utilization and mineral resource processing, and in particular relates to a method for selectively enriching scandium from Bayer process red mud. Background technique [0002] Scandium is an important strategic resource widely used in high-tech fields such as optics, electronics, aviation, automobiles, and superconductivity. Scandium is an associated scattered element, and there is no independent deposit in nature. It is mainly recovered as a by-product from the low-alkali iron-rich slag, tailings and waste liquid that produce other metals such as rare earths, aluminum, titanium, tungsten, and magnesium. [0003] Red mud is alkaline solid waste generated during the production of alumina from bauxite. It is estimated that every ton of alumina produced produces 1-1.5 tons of red mud. About 150 million tons of red mud are produced every year in the world. At present, the accumulat...

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Problems solved by technology

[0005] However, there are still some problems in the recovery of scandium in red mud: (1) most of the current extraction methods use direct acid leaching to process red mud. Solid-liquid separation is difficult, and the silicon content in the solution is too high. When extracting scandium, a large amount of emulsion is easily produced, which makes the separation of the organic phase difficult and increases the difficulty of subsequent processes.

(2) The content of iron in red mud is relatively high, and the co-leaching of iron affects the recovery of scandium. If the iron in red mud is separated and pretreated, the existing process route is relatively complicated, the energy consumption is high, the consumption of acid and alkali is large, and the increase processing cost

(3) After the existing treatment method extracts valuable metals from the red mud, since other components in the red mud remain in the slag, there is still a large amount of waste slag discharged, and the original alkaline waste slag becomes acidic waste slag. Fundamentally solve the problem of mass storage of waste residue, and the acid cannot be recycled and reused, resulting in a large amount of waste acid, causing pollution to groundwater and damage to the environment

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