Extracting value from aluminum production waste (red mud)

Transcription

1 Extracting value from aluminum production waste (red mud) 5 th Scientific Seminar december 2018 Berlin, Germany Extracthive Bâtiment 51, Site de Marcoule BagnolsCèze, Cedex, France Abdoulaye MAIHATCHI

2 I I IV Company presentation About Extracthive Extracthive is a French company specialized in the recycling of industrial waste: 3 locations 40 employees 3.7 M in revenue expected (e2018) Extracthive Process Designer: Our RDI team Extracthive Ceramics Recycling: Our comminution facility Extracthive Chemical Products: Our chemical plant 2

3 I I IV Company presentation About Extracthive Process Designers Lab scale (2l) development of a process to recover antimony from stibnite ore : Stibnite ore (Sb content 5 w%) HCl, Air Oxidative leaching CaCO 3 Neutralisation NaOH Precipitation Sb 2 O 3 concentrate (Sb content > 60% ) 3

4 I I IV Company presentation About Extracthive Process Designers Valorization of jarosite, a zinc by-product rich in iron, as a secondary source of zinc, iron and lead. Jarosite (Fe, Zn, Pb) H 2 SO 4 Leaching Solution Source of PbSO 4 Residue Electrowinning Electrolytic alloy Fe/Zn 4

5 I I IV Introduction / Context Sources of red mud: bauxite ore Bauxite reserves (78 billon tons) [1] Uses of aluminum [1] United States Geological Survey Website (USGS), «Bauxite and Alumina, commodity Statisctics and Information»,

6 I I IV Introduction / Context Alumina production Bauxite Alkaline leaching S/L separation S/L separation 60 %wt. Al 2 O 3 20 %wt. Fe 2 O C Washing S/L separation Hydrated alumina NaOH Red mud Waste management : - Building material - Pollutant adsorbent - 70Mt Per year [2] 50 %wt. Fe 2 O 3 Ajka (Hungury), 2010 [2] Harekrushna Sutar et al., «Progress of Red Mud Utilization: An Overview», American Chemical Science Journal, p ,

7 Density vol. (%) I I IV Introduction / Context Red mud characterization Samples used in this study have been characterized by XRD, SEM and ICP-AES. Fe 2 O 3 Al 2 O 3 SiO 2 TiO 2 CaO P 2 O 5 MgO Cr 2 O 3 Na 2 O LOI 48.8 % 12.3 % 5.70 % 9.45 % 5.34 % 0.480% 0.140% 0.310% 3.26 % 11.7% 6 50µm , Size (µm) TiO 2 NaAlSiO 4 Fe 50 2 µm O 3 Fe 2 O 3 +Al 2 O 3 7

8 I I IV Introduction / Context Objectives reduction of waste volume, production of electrolytic iron, thus creating added value, access to other metals contained in the residues (like titanium). Bauxite Alkaline leaching S/L separation Cristallization S/L separation Mixing Red Mud NaOH Hydrated alumina Electrowinning 110 C Electrolytic iron Water +NaOH S/L separation Solid residue 8

9 I I IV Experimental Experimental device Reference electrode Cathode Anode Electrolysis cell Oil circulation 9

10 Faradaic efficiency (%) I I IV Results Effect of current density 90 Hematite Bauxite residue 93 % 93 % Fe 2 O % 20 % RM Current density ( A/m²) Faradaic yields vs. current density in a suspension of NaOH-hematite and M NaOH-Red mud at 110 C. The low yield obtained in the case of bauxite residue can be explained by the presence of impurities in the medium (vanadium, silicates,..). 10

11 Intensity (u,a) I I IV Results Analysis of electrolytic iron % Fe % Na % Al Fe-hematite Fe-red mud Fe-Hematite Fe-Red mud Fe-hematite * graphite peak * THETA ( ) Fe- Red mud These results confirm the feasibility of producing electrolytic iron from red mud! 11

12 I I IV Conclusion To conclude Our objective was to study the feasibility of production of iron from red mud. Red mud analysis has shown that it contains about 50% wt. hematite The electrolytic iron obtained has a purity greater than 99 % and 97 % respectively for hematite and red mud. The maximum faradaic yields of electrodeposition were of the order of 93% and 20% respectively for hematite and red mud. Prospect To improve faradaic yields, it can be proposed to: (i) Find a way to inhibit the effect of impurities, (ii) Eliminate impurities by pretreatment of the red mud before electrodeposition. 12

13 Thank you for your attention