The invention relates to the metallurgical industry, specifically to the acid treatment of red mud obtained in the process of producing alumina, and can be used in technologies for recycling waste from alumina refinery holding ponds. The method for the acid treatment of red mud involves leaching using a leaching agent comprised of water-soluable aliphatic carbonic acids having fewer than 3 carbon atoms per molecule, filtering the solution, and separating the recoverable end products. To ensure a high level of recovery of valuable components and the increased productivity of the process, leaching is conducted with the addition of red mud in portions and with the control of pH values, and when a target pH value of between 2.3 and 3.8 is reached, no more red mud is added, and once leaching is complete, the solution is kept at a given leaching temperature for no less than one hour.

A method for recovering lead oxide from a pre-desalted lead paste, comprising the following steps: a. dissolving the pre-desalted lead plaster by using a complexing agent solution, and making all of PbO therein react with the complexing agent to generate lead complexing ions, obtaining a lead-containing solution and a filter residue; b. adding a precipitant to the lead-containing solution, and then the precipitant reacting with the lead complexing ions to generate a lead salt precipitate and the regenerated complexing agent; c. calcining the lead salt precipitate to obtain lead oxide and regenerate the precipitant. The final recovery rate of lead oxide of the method can reach 99% or more.

A process for recovering chromium from hexavalent chromium-containing wastewater comprises the following steps: (1) extracting hexavalent chromium in wastewater to an organic phase by using an extracting agent, and separating hexavalent chromium from a water phase, so as to acquire a hexavalent chromium-loaded organic phase; (2) reducing the hexavalent chromium-loaded organic phase by using an aqueous solution of an organic reducing agent, reducing hexavalent chromium into trivalent chromium, reversely extracting trivalent chromium into the water phase, and separating the organic phase from the water phase to acquire a solution of the trivalent chromium and a renewable organic phase, wherein the organic reducing agent is one or a mixture of alcohols, aldehydes and carboxylic acids having the carbon atom number ranging 1 to 3; and (3) performing solvent evaporation on the solution of trivalent chromium, catalyzing, and recovering the trivalent chromium.

According to the invention, a method for treating electronic waste with a view to individually recovering metals included in such waste is provided. Said method is characterized in that it includes the series of the following steps: grinding the waste under conditions suitable for individually separating the different metal components of the waste; mixing the ground waste with a liquid such as to form a suspension; gravitationally separating the suspension such as to separate the particles having the highest densities and containing the majority of the metals from the particles having the lowest densities; and densimetrically separating the suspension containing the majority of the metals such as to obtain suspensions containing the individually separated metals.

The present invention related to generally to a process to recover metals from waste electronics, and more particularly a process to recover gold from waste electronics. The gold is first delaminated in a first step using a solution containing a weak acid in combination with an oxidizer. The second step isolates and purifies the delaminated gold from the chip debris using solvents, water and a wetting agent/surfactant. The proposed two step method of gold recovery from electronic waste is effective without the need for strong or costly chemicals or leaching.

Processes are described for extracting metals from a combination derived from spent lithium-ion batteries and comprising such metals, a liquid, an acid, and other components.

Methods for recovering metals from metal-containing materials are provided. The metal-containing material comprises either Co and Li (e.g., an electrode material from a spent lithium ion battery) or Fe and Al (e.g., bauxite). The metal-containing material is exposed to a leaching solution comprising ammonium hydrogen oxalate, oxalic acid, or both, to provide a solid composed of either cobalt oxalate or iron oxalate, and a solution of either lithium oxalate or aluminum oxalate. The solid is processed to provide either cobalt oxide or iron oxide; the solution is processed to provide either a lithium precipitate or an aluminum precipitate, and a filtrate comprising an oxalate; and the filtrate comprising the oxalate is processed to recover ammonium hydrogen oxalate, oxalic acid, or both. The method further comprises repeating the digestion step with the recovered ammonium hydrogen oxalate, the recovered oxalic acid, or both.

This invention provides a membrane electrode material and its preparation method, as well as the application of the material into lithium extraction by adsorption-electrochemical coupling method. The membrane electrode material is described as MnO@C. The preparation steps are as follows: LiMn.sub.2O.sub.4 is firstly obtained by calcining lithium carbonate and manganese carbonate, which is then dispersed in hydrochloric acid solution. After stirring and separating, the solid products are dried to obtain λ-MnO.sub.2. The λMnO.sub.2 is added to the raw material of Mn-MOF-74, and then the Mn-MOF-74 coated λ-MnO.sub.2 can be obtained by hydrothermal reaction. By further calcining Mn-MOF-74 coated λ-MnO.sub.2 in nitrogen atmosphere, the membrane capacitor/electrode material can be obtained as MnO@C. The material is fabricated into an adsorption film electrode plate and assembled into an adsorption-electrochemical coupling lithium extraction device. The pure lithium solution can be obtained in the recovery pool through the combined lithium extraction and lithium recovery process. In this invention, the thickness of the carbon coating layer in the electrode material is adjustable. Adsorption-electrochemical coupling technology takes the advantages of both adsorption and electrochemical lithium intercalation, which can extract and recover lithium resources with high capacity. Thus, this invention not only achieves high-efficiency separation of lithium resources, but also opens up a new way for the extraction of lithium resources.

A plant for recovering metals and/or metal oxides from industrial process waste, in particular oil product refining waste, comprises a furnace; a feed line connected to a main inlet of the furnace and configured to feed the furnace with a solid waste containing metals, in particular in oxide form; an outlet line, connected to a solid phase outlet of the furnace and configured to draw a metal-enriched solid phase out of the furnace; the furnace is a belt conveyor furnace having a belt conveyor closed in a loop with a substantially horizontal configuration and having a top face, which receives the waste to treat and conveys it between two longitudinal opposite ends of the belt conveyor furnace respectively provided with the main inlet and the solid phase outlet.

The present invention is a CO.sub.2 based hydrometallurgical multistage reaction and separation system comprising: a pre-washing device configured to fully mix the feedstock, such as industrial solid waste, mineral and mine tailings with auxiliary reagents and water at specific ratio, a reactor configured to treat the washed slurry with CO.sub.2 bubbling and discharge the treated slurry to the next stage, multistage separators configured to separate solid particles from treated slurry and recycle the unreacted solids back into the pre-washing device, a by-product preparation device configured to generate calcium and magnesium based products from filtrate containing target elements, a water recirculating device configured to recycle the remaining liquor back to the system. The present invention ensures the whole system is able to continuously and consistently react at maximum capacity through continuous slurry feeding and CO.sub.2 bubbling into the reactors which also enables multistage circulating reaction.