Alkalinity stabilization behavior of bauxite residue: Ca-driving regulation characteristics of gypsum

Abstract

Alkaline anions, include CO₃^2–, HCO₃^–, Al(OH)₄^–, OH^–, continuously released from bauxite residue (BR), will cause a potential disastrous impact on surrounding environment. The composition variation of alkaline anions, alkaline phase transformation pathway, and micro-morphological transition characteristics during the gypsum addition were investigated in an attempt to understand alkalinity stabilization behavior. Results demonstrated that alkaline anions stabilization degree in leachates can reach approximately 96.29%, whilst pH and alkalinity were reduced from 10.47 to 8.15, 47.39 mmol/L to 2 mmol/L, respectively. During the alkalinity stabilization, chemical regulation behavior plays significant role in driving the co-precipitation reaction among the critical alkaline anions (CO₃^2–, HCO₃^–, Al(OH)₄^–, OH^–), with calcium carbonate (CaCO₃)) being the most prevalent among the transformed alkaline phases. In addition, XRD and SEM-EDX analyses of the solid phase revealed that physical immobilization behavior would also influence the stability of soluble alkali and chemical bonded alkali due to released Ca²⁺ from gypsum which aggregated the clay particles and stabilized them into coarse particles with a blocky structure. These findings will be beneficial for effectively regulating strong alkalinity of BR.

Keywords

bauxite residue / gypsum / alkalinity stabilization / phase transformation / Ca-driven regulation

References

[1] PowerG, GrafeM, KlauberC. Bauxite residue issues: I. Current management, disposal and storage practices [J]. Hydrometallurgy, 2011, 108: 33-45

[2] XueS, KongX, ZhuF, HartleyW, LiX, LiYi. Proposal for management and alkalinity transformation of bauxite residue in China [J]. Environmental Science and Pollution Research, 2016, 23: 12822-12834

[3] CaoJ, WuQ, LiH, OuyangC, KongH, XiXiao. Metallogenic mechanism of Pingguo bauxite deposit, western Guangxi, China: Constraints from REE geochemistry and multi-fractal characteristics of major elements in bauxite ore [J]. Journal of Central South University, 2017, 24: 1627-1636

[4] PanX, YuH, TuGan. Reduction of alkalinity in bauxite residue during Bayer digestion in high-ferrite diasporic bauxite [J]. Hydrometallurgy, 2015, 151: 98-106

[5] XueS, ZhuF, KongX, WuC, HuangL, HuangN, HartleyW. A review of the characterization and revegetation of bauxite residues (Red mud) [J]. Environmental Science and Pollution Research, 2016, 23: 1120-1132

[6] XuG, DingX K M, ZhouW B W. Research and application of non-traditional chemical stabilizers on bauxite residue (red sand) dust control, a review [J]. Science of the Total Environment, 2018, 616–617: 1552-1565

[7] JohnstonM, ClarkM W, McmahonP, WardN. Alkalinity conversion of bauxite refinery residues by neutralization [J]. Journal of Hazardous Materials, 2010, 182: 710-715

[8] KirwanL J, HartshornA, McmonagleJ B, FlemingL, FunnellD. Chemistry of bauxite residue neutralisation and aspects to implementation [J]. International Journal of Mineral Processing, 2013, 119: 40-50

[9] MayesW M, JarvisA P, BurkeI T, WaltonM, FeiglV, KleberczO, GruizK. Dispersal and attenuation of trace contaminants downstream of the ajka bauxite residue (red mud) depository failure, Hungary [J]. Environmental Science & Technology, 2011, 45: 5147-5155

[10] LiuW-C, ChenX, LiW, YuY, YanKun. Environmental assessment, management and utilization of red mud in China [J]. Journal of Cleaner Production, 2014, 84: 606-610

[11] ZhuF, LiaoJ, XueS, HartleyW, ZouQ, WuHao. Evaluation of aggregate microstructures following natural regeneration in bauxite residue as characterized by synchrotron-based X-ray micro-computed tomography [J]. Science of the Total Environment, 2016, 573: 155-163

[12] BurkeI T, PeacockC L, LockwoodC L, StewartD I, MortimerR J G, WardM B, RenforthP, GruizK, MayesW M. Behavior of aluminum, arsenic, and vanadium during the neutralization of red mud leachate by HCl, gypsum, or seawater [J]. Environmental Science & Technology, 2013, 47: 6527-6535

[13] GrafeM, PowerG, KlauberC. Bauxite residue issues: III. Alkalinity and associated chemistry [J]. Hydrometallurgy, 2011, 108: 60-79

[14] KongX, JiangX, XueS, HuangL, HartleyW, WuC, LiXiao. Migration and distribution of salinity in bauxite residue during water leaching [J]. Transactions of Nonferrous Metals Society of China, 2017, 28(3): 534-541

[15] HaynesR J. Bauxite processing residue: A critical review of its formation, properties, storage, and revegetation [J]. Critical Review Environmental Science and Technology, 2011, 41: 271-315

[16] LiX, YeY, XueS, WuC, KongX, HartleyW, LiYi. Leaching optimization and dissolution behavior of alkaline anions in bauxite residue [J]. Transactions of Nonferrous Metals Society of China, 2018, 28: 1248-1255

[17] MenziesN W, FultonI M, MorrellW J. Seawater neutralization of alkaline bauxite residue and implications for revegetation [J]. Journal of Environmental Quality, 2004, 33: 1877-1884

[18] XueS, WuY, LiY, KongX, ZhuF, WilliamH, LiX, YeYu. Industrial wastes applications for alkalinity regulation in bauxite residue: A comprehensive review [J]. Journal of Central South University, 2019, 26(2): 268-288

[19] CourtneyR, KirwanL. Gypsum amendment of alkaline bauxite residue-plant available aluminium and implications for grassland restoration [J]. Ecological. Engineering, 2012, 42: 279-282

[20] SantiniT C, FeyM V. Spontaneous vegetation encroachment upon bauxite residue (red mud) as an indicator and facilitator of in situ remediation processes [J]. Environmental Science & Technology, 2013, 47: 12089-12096

[21] KinnarinenT, LubienieckiB, HollidayL, HelstoJ J, HakkinenA. Recovery of sodium from bauxite residue by pressure filtration and cake washing [J]. International Journal of Mineral Processing, 2015, 141: 20-26

[22] HanY S, JiS, LeeP K, OhC. Bauxite residue neutralization with simultaneous mineral carbonation using atmospheric CO2 [J]. Journal of Hazardous Materials, 2016, 326: 87-93

[23] XueS, LiM J J M G J, LiC, KongXiang. Phosphogypsum stabilization of bauxite residue: conversion of its alkaline characteristics [J]. Journal of Environmental Sciences, 2019, 77: 1-10

[24] ZhuF, HouJ, XueS, WuC, WangQ, HartleyW. Vermicompost and gypsum amendments improve aggregate formation in bauxite residue [H]. Land Degradation & Development, 2017, 28(7): 2109-2120

[25] HuangY, ChaiW, HanG, WangW, YangS, LiuJiong. A perspective of stepwise utilisation of Bayer red mud: Step two—Extracting and recovering Ti from Ti-enriched tailing with acid leaching and precipitate flotation [J]. Journal of Hazardous Materials, 2016, 307: 318-327

[26] WhittingtonB I, FletcherB L, TalbotC. The effect of reaction conditions on the composition of desilication product (DSP) formed under simulated Bayer conditions [J]. Hydrometallurgy, 1998, 49: 1-22

[27] WongJ W C, HoG E. Use of waste gypsum in the revegetation on red mud deposits: A greenhouse study [J]. Waste Mangement & Research, 1993, 11: 249-256

[28] MayesW M, AndP L Y, AumoN J. Buffering of alkaline steel slag leachate across a natural wetland [J]. Environmental Science & Technology, 2006, 40: 1237-1243

[29] XueS, YeY, ZhuF, WangQ, JiangJ, HartleyW. Changes in distribution and microstructure of bauxite residue aggregates following amendments addition [J]. Journal of Environmental Sciences, 2019, 78: 276-286

[30] LiY, JiangJ, XueS, MillarG, KongX-f, LiX, LiM, LiChu. Effect of ammonium chloride on leaching behavior of alkaline anion and sodium ion in bauxite residue [J]. Transactions of Nonferrous Metals Society of China, 2018, 28(10): 2125-2134