Processing of red mud in bauxite refining

A method of processing pulp, wherein the pulp comprises a mixture of ground ore and water that is extracted from the red mud obtained in processing bauxite, the method comprising:

• (i) filtering the pulp to obtain a first filter cake and a first filtrate;
• (ii) leaching aluminum from the first filter cake by adding, to the first filter cake, sodium hydroxide (NaOH) solution to form an aluminum-containing first slurry;
• (iii) filtering the first slurry to obtain an aluminum-containing second filter cake and a second filtrate;
• (iv) precipitating, from the second filtrate in the presence of carbon dioxide (CO2) gas, first aluminum compounds that include sodium hydroaluminocarbonate and aluminum hydroxide;
• (v) leaching aluminum from the second filter cake, by adding, to the second filter cake, NaOH solution, to form a second slurry;
• (vi) filtering the second slurry to obtain a third filter cake and an aluminum-containing third filtrate;
• (vii) precipitating, from the third filtrate, second aluminum compounds comprising sodium hydroaluminocarbonate and aluminum hydroxide;
• (viii) combining a solution of sodium carbonate (Na2CO3) and carbon dioxide (CO2) to obtain a solution of Na2CO3 and sodium bicarbonate (NaHCO3);
• (ix) leaching titanium (Ti), zirconium (Zr) and scandium (Sc) from the third filter cake by adding the solution of Na2CO3 and NaHCO3 to the third filter cake to form a third slurry;
• (x) filtering the third slurry to obtain both a fourth filter cake and a fourth filtrate that includes Ti, Zr and Sc;
• (xi) precipitating out titanium oxide (TiO2) from a mixture of the fourth filtrate and NaOH solution, leaving behind a first supernate solution that includes Zr and Sc;
• (xii) heating a mixture that includes the first supernate solution and NaOH and an aluminum-based coagulant, to yield a precipitate that includes Zr and Sc;
• (xiii) leaching Zr and Sc from the fourth filter cake, by adding the solution of Na2CO3 and NaHCO3 to the fourth filter cake to form a fourth slurry;
• (xiv) filtering the fourth slurry to obtain an iron-containing fifth filter cake and a fifth filtrate;
• (xv) precipitating out TiO2 from a mixture of the fifth filtrate and a NaOH solution, leaving behind a second supernate solution that includes Zr and Sc;
• and
• (xvi) heating a mixture that includes the second supernate solution and NaOH and an aluminum-based coagulant, to yield a precipitate that includes Zr and Sc.