Antimony Recovery from Lead-Rich Dross of Lead Smelter and Conversion into Antimony Oxide Chloride (Sb₄O₅Cl₂)

Abstract

Antimony was selectively leached from a lead-rich industrial process residue called 'dross', and recovered as an antimony oxide chloride (Sb4O5Cl2), which can be used as a component in flame retardants or as an anode material in aqueous chloride batteries. The dross is a residue generated by a lead smelter and it contained about 30 wt% of lead and about the same concentration of antimony, along with some minor metals such as zinc, iron and tin. Solutions of hydrochloric acid dissolved in organic solvents such as ethanol, 1-octanol, ethylene glycol and Aliquat 336 chloride were compared for selective leaching of antimony. All investigated lixiviants leached comparable amounts of antimony (60−76%), but the lowest co-dissolution of lead (~0.1%) was achieved by hydrochloric acid in ethanol or in 1-octanol. Only ethanol was chosen for further investigation since it is significantly cheaper than 1-octanol. Moreover, ethanol is classified as an environmentally preferable green solvent. Hydrochloric acid in ethanol leached much less lead than using water, and the former also required lower chloride concentration to get high leaching yields of antimony. Leaching under optimized conditions was successfully upscaled in a 1 L batch leaching reactor, achieving an antimony leaching efficiency of 90% (28000 mg L -1 ) and a lead leaching efficiency of only 0.4% (100 mg L -1 ). The dissolved antimony in the pregnant leach solution (PLS) was fully recovered by hydrolysis precipitation whereby high-purity antimony oxide chloride (Sb4O5Cl2) was obtained, by adding to the PLS an equivalent volume of water.The ethanol in the remaining PLS was distilled to be reused for more leaching. The valorization of an industrial process residue and the use of ethanol contribute to the sustainability and the greenness of the process.

The Layered Semiconductor Cu(Sb2S3)[AlCl4]

“…We assume a hydrolysis of the [AlCl 4 ] – anions, in which acidic [Al(H 2 O) 6 ] 3+ (p K a =4.97) is formed on the surface of the initial crystals (Equation 2). Sb 4 O 5 Cl 2 (besides SbOCl) is a known product of the hydrolysis of SbCl 3 in acidic aqueous solutions [51–53] . Here, Sb 4 O 5 Cl 2 could have formed via an intermediate compound “Cu(Sb 2 S 3 )Cl” (see below) by a solution process in which the antimony and part of the sulfide ions are removed from the crystal (Equation 3).…”

“…Sb 4 O 5 Cl 2 (besides SbOCl) is a known product of the hydrolysis of SbCl 3 in acidic aqueous solutions. [51][52][53] Here, Sb 4 O 5 Cl 2 could have formed via an intermediate compound "Cu(Sb 2 S 3 )Cl" (see below) by a solution process in which the antimony and part of the sulfide ions are removed from the crystal (Equation 3). The aluminum-containing hydrolysis product did not solidify and was therefore not detected in the EDX or the diffractogram.…”

Recovery of Sb(Ⅲ) from Aqueous Solution as Cubic Sb2O3 by Fluidized-Bed Granulation Process

“…Then, the generated Sb 4 Cl 2 O 5 was further converted into Sb 2 O 3 with an excellent crystal form and high purity by using Na 2 CO 3 , NaOH, or NH 4 OH as mediating agents. Palden et al [22] compared the effects of potassium carbonate, sodium sulfide, and water on the precipitation of antimony from lead dross, and found that Sb(III) in solution can undergo hydrolysis in water to generate Sb 4 Cl 2 O 5 . These investigations presented the potential for utilizing the granulation process in antimony recovery.…”

Effect of pH Hydrolysis on the Recovery of Antimony from Spent Electrolytes from Copper Production

“…Similarly, the presence of Sb 2 O 3 became apparent within a pH range of approximately 8 to 9. Accordingly, researchers in [23] generate Sb 4 O 5 Cl 2 by adding water into an ethanol-based HCl solution with a concentration of 2 mol/L. Total precipitation is determined to occur in a volumetric ratio of 1 between the added water and original solution.…”