Effect of Structure on the Geotechnical Properties of Bauxite Residue

Abstract

This paper describes a laboratory program to investigate the mechanical and physicochemical properties of bauxite residue ͑red mud͒ at a site in the United Kingdom. The red mud storage facility has been recently decommissioned and has been considered for future rehabilitation and construction activity. Based on a suite of laboratory tests conducted on the red mud, the material has compression behavior similar to clayey soils, but frictional behavior closer to sandy soils. The red mud appears to be "structured" and has features consistent with sensitive, cemented clay soils. Chemical testing suggests that the agent causing the aggregation of particles is hydroxysodalite and that the bonds are reasonably strong and stable during compressive loading. Exposure of the red mud to acidic conditions causes dissolution of the hydroxysodalite and a loss of particle cementation. Hydration of the hydroxysodalite unit cells is significant, but does not affect the mechanical performance of the material. The shape, size, and electrically charged properties of the hydroxysodalite, goethite, and hematite in the red mud appear to be causing mechanical behavior with features consistent with clay and sand, without the presence of either quartz or clay minerals.

Tailings composition effects on shear strength behavior of co-mixed mine waste rock and tailings

“…11a). These tailings had the highest clay-sized content of all materials evaluated (Table 1), and the clay content likely contributed to contractive tendencies [23,25]. Although soda ash tailings were contractive, they also were stiff during initial loading that was followed by attainment of an ultimate strength at small e a (Fig.…”

“…Soda ash tailings contained 18.0 % clay (Table 1) and clay particle flocculation may have contributed to an increase in shear strength. Newson et al [23] conducted CU triaxial compression tests on bauxite residue that had similar Atterberg limits, particle-size distribution, and pore fluid chemistry to the soda ash tailings. Results from triaxial tests on the bauxite residue in Newson et al [23] yielded a / 0 of 42°, which is consistent with results obtained for soda ash tailings.…”

“…Newson et al [23] conducted CU triaxial compression tests on bauxite residue that had similar Atterberg limits, particle-size distribution, and pore fluid chemistry to the soda ash tailings. Results from triaxial tests on the bauxite residue in Newson et al [23] yielded a / 0 of 42°, which is consistent with results obtained for soda ash tailings. Additional evaluation is needed to assess the effects of salinity on shear strength of mine tailings.…”

Pelarutan bijih bauksit dengan soda kaustik (NaOH) menjadi larutan sodium aluminat (NaAlO2) skala pilot

“…Red mud hasil pelarutan bauksit Tayan, Kalbar dengan NaOH mengandung lima (5) komponen mineral utama yaitu kuarsa, sodalit, gibsit, gutit, dan hematit (Gambar 8); sedangkan menurut hasil penelitian Castaldi (2008Castaldi ( , 2011, red mud yang mengandung sekitar 80% (berat) fasa kristalnya memiliki empat (4) komponen utama yaitu: sodalit, hematit, gibsit, dan bohmit; hasil penelitian Liang (2013) menunjukkan bahwa sekitar 70% (berat) dari red mud hasil penelitiannya mengandung empat (4) komponen utama yaitu hematit (Fe2O), gibsit (Al(OH)3, bohmit (AlO(OH)), sodalit (Na8(Al6Si6O24)Cl2/ (Na8(Al6Si6O24)CO3; hasil penelitian Feret (2013), komponen utamanya adalah sodalit (Na8,08 Al6Si6O28,88 S0,98), cancrinite (Na7,14 Al6Si6O31,6), cancrinite NO3 (Na7,92 Al6Si6O31,56 N1,74) dan nosean (Na8Al6Si6O28S) dan hasil penelitian Newson (2006) …”

The effect of chemical and mineralogical composition of red mud on alkalinity parameters

“…Pokazano je da DSP-i pokazuju najveći kapacitet puferovanja kod pH = 7 i strmu (oštru) fleksiju tačke u blizini pH = 5 kada je rastvoren i poslednji od prisutnih DSP-a [29]. Ovaj rezultat je u skladu sa zapažinjima o slabljenju XRD pikova desilikacionih proizvoda (kankrinita i sodalita) pri tretmanu mulja kiselinama i njihovom potpunom nestanku sa padom pH, izazvanim dodatkom koncentrovanije kiseline [36][37][38]. Sa druge strane višestruko ispiranje sirovog crvenog mulja, nije dovelo do smanjenja intenziteta XRD pikova ni sodalita ni kalcita [39].…”