The present disclosure provides a method for co-extraction of vanadium, titanium and chromium from vanadium slag. The method selectively reduces pyroxene and fayalite wrapped on spinel through low-temperature hydrogen reduction, iron removal by ferric chloride, and low-temperature leaching of the vanadium slag by oxalic acid, thereby destroying a structure of the spinel, dissociating a spinel phase and a silicate phase, and fully exposing the spinel phase. The method also directly leaches the vanadium slag at a low temperature by acidity and strong complexation of the oxalic acid, and destroys the structure of the spinel, such that vanadium, titanium, chromium and oxalate are complexed into a solution to co-extract vanadium, titanium and chromium. The present disclosure extracts vanadium, titanium and chromium from the vanadium slag, with a leaching rate each being greater than 99%.

A method for preparing self-doped titanium-niobium oxide negative electrode material using a waste titanium dioxide carrier includes preparing self-doped TiNb.sub.2O.sub.7 negative electrode material for lithium-ion battery by using waste titanium dioxide carrier comprises the following steps: S1. converting a waste titanium dioxide carrier into TiO.sub.2 powder with the Ti content of 95% and the Al content of 0.1-4.0%, based on the weight of oxide, respectively; and S2. mixing the TiO.sub.2 powder and Nb.sub.2O.sub.5 powder to form a mixture, roasting the mixture, and collecting the generated Al self-doped TiNb.sub.2O.sub.7, so as to obtain the self-doped TiNb.sub.2O.sub.7 negative electrode material. According to the method disclosed by the present invention, impurities represented by TiO.sub.2 and Al.sub.2O.sub.3 in the waste titanium dioxide carrier can be directly recycled, a self-doped TiNb.sub.2O.sub.7 (titanium niobium oxide) negative electrode material.

A method for extracting metal values from a low grade primary metal oxide ore feedstock is provided. The method includes providing a low grade primary metal oxide ore containing a primary metal and scandium; subjecting the ore to acid leaching, thus yielding an acidic leachate; extracting the primary metal and scandium from the leachate, thereby yielding an acidic barren leachate; and using the acidic barren leachate in a subsequent iteration of the acid leaching step.

A method of processing red mud comprising: heating red mud to a predetermined temperature; grinding the red mud to a predetermined particle size; and physically extracting iron components from the red mud; physically extracting aluminum components from the red mud, said physically extracting of aluminum components being separate from the physically extracting of iron components, wherein the steps of physically extracting iron components and physically extracting aluminum components are performed without requiring addition of chemical additives to the red mud.

A system for processing red mud including at least one heating section controlled to heat red mud to a predetermined temperature, a crusher configured to grind the red mud to a predetermined particle size, a first separator for physically extracting iron components from the red mud, and a second separator for physically extracting one or more of aluminum components and titanium components from the red mud, wherein the first and second separators do not require addition of chemical additives to perform the separation.

A method of making upgraded synthetic rutile (100) can include binding ilmenite ultrafine particles together with a binder to form green pellets (110). Iron can be reduced in the green pellets by heating the green pellets to a reducing temperature under a reducing atmosphere (120). The ilmenite ultrafine particles within the green pellets can be at least partially sintered together by heating the green pellets at a sintering temperature to form at least partially sintered pellets (130). Iron can be removed from the at least partially sintered pellets by leaching to form upgraded synthetic rutile (140).

This invention refers to a technically and economically viable process for recovery of relevant metallic and non-metallic contents from mining residues, particularly the bauxite residue, using it in its integral form. Such a process route uses energy from microwaves, assisted leaching and logic sequencing of steps that allow a technically and economically viable removal of components from the bauxite residue, particularly the residue from the Bayer process. The invention also refers to a microwave reactor that is appropriate for performing the above-mentioned process, as well as to a method for heating a mining product.