The method of extraction of rare-earth metals, scandium and yttrium from the red mud of alumina production

 

(57) Abstract:

The invention relates to ferrous metallurgy and can be used to obtain the rare metal. The essence of the invention is that the slurry of red mud are divided by the density of the light and heavy fractions, after which the light fraction is subjected to magnetic separation in a magnetic field 400-1600 kA/m Implementation of the method can reduce the amount of harmful impurities in the resulting concentrate and to increase the degree of extraction of rare-earth metals, scandium and yttrium. table 2.

The invention relates to ferrous metallurgy and can be used to obtain a rare non-ferrous metals.

The method for extracting scandium from red mud based on the acid treatment of the sludge with obtaining soluble compounds extracted product. C. the USSR N 1321089). The disadvantages of this method are strong contamination of the acid solution of the compounds of the main components contained in the sludge (Al₂O₃, SiO₂, CaCO₃and others), low concentration of scandium in the acid solution, which makes his selection from the solution, a significant consumption of acid.

As the prototype is the classification and magnetic separation of the sludge when the magnetic field strength 30 - 80 kA/m.with. USSR N 1715874). The disadvantages of this method are considerable content of harmful impurities in the resulting magnetic concentrate and not a high degree of extraction of scandium.

The problem to be solved by the proposed method is to reduce the amount of harmful impurities in the resulting concentrate and increase the degree of extraction of rare-earth metals, scandium and yttrium.

The solution of the stated problem is achieved in that the method includes obtaining a slurry of red mud and magnetic separation to obtain a magnetic concentrate containing iron, rare earth metals, scandium and yttrium, before magnetic separation of red mud is subjected to separation by density on light and heavy fractions, and subjected to magnetic separation of light fraction when the voltage of the magnetic field of 400 - 1600 kA/m

When extracting rare earth metals, scandium and yttrium from red mud harmful impurities are compounds of aluminum, silicon, calcium and other elements. They form when the acid leaching of rare earth metals from the magnetic concentrate truefilter connection type gels, which does not allow to separate rare earth metals, as well as mo/P> When the separation of the red mud density in the heavy fraction of moving a large part of carbonates, magnetite, sulfides and protocrystalline hematite. As a result, the amount of harmful impurities in the resulting magnetic concentrate is reduced.

The chemical composition of red mud, a light fraction of red mud and the magnetic concentrate is given in table. 1. wt.% .

Reducing the amount of harmful impurities in the light fraction gives the possibility to change the modes of the process of magnetic separation, which will increase the degree of extraction of rare-earth metals, scandium and yttrium. The results of experiments with different values of magnetic field strength are given in table. 2.

When the magnetic field strength below 400 kA/m extraction of rare-earth metals, scandium and yttrium drops below 50%, which leads to large losses of metals.

When the voltage of the magnetic field over 1600 kA/m deteriorates the quality of the concentrate due to the growth of harmful impurities.

Speed is as follows.

Red mud in the form of a slurry with solid content up to 50% are served in a centrifugal concentrator with continuous discharge of the heavy fraction (Robina acceleration 40 - 100 m/sec. Then a light fraction of the sludge is subjected to magnetic separation in a magnetic field of 400 - 1600 kA/m

The extraction of rare earth metals, scandium and yttrium from the received magnetic concentrate is carried out by any known method, such as acid leaching.

The method of extraction of rare-earth metals, scandium and yttrium from the red mud of alumina production, including the production of a slurry of red mud and magnetic separation to obtain a magnetic concentrate containing iron, rare earth metals, scandium and yttrium, characterized in that before the magnetic separation of red mud is subjected to separation by density on light and heavy fractions, and subjected to magnetic separation of light fraction in magnetic field strength of 400 - 1600 kA/m