Hydrometallurgical extraction of antimony from lead refining slags

Today, in order to optimize the production of copper, zinc, and lead, as well as to reduce the circulation of associated metal impurities (such as antimony, tin, bismuth and others) between the processing facilities, an ever greater attention is given to the development and implementation of processing schemes that would enable to extract associated metals and use them to produce commodities. In connection with the above, a process has been developed and tested for processing lead refining slags which include, %: 25–30 Sb, 2–10 Pb, 1–8 Sn, 3–12 As, 0.1–0.2 Cu. The resultant products included the Su-2, Su-1 and Su-0 grades of antimony or antimonous oxide. It was found that the forms in which antimony was present in the untreated slag included Sb2O3, Sb2O4, Sb2O5 and NaSb(OH)6. A hydrometallurgical process based on the use of sulphide alkaline solutions was taken as the basic slag processing technique. It is proposed to wash the slag additionally before leaching to remove arsenic from antimony, and to use the electrowinning stage to separate tin from antimony. Regimes have been identified for obtaining cathode deposits containing 96–99% Sb, with the recovery of antimony from untreated slag being 67%. The cathode deposits were refined with the help of pyrometallurgical methods and electrolysis in sulphate-fluoride media. The paper also considers the possibility of obtaining antimonous oxide by oxidizing the antimonous oxide melt and recovering Sb2O3 from exhaust gases. Based on the findings and the results of the tests, Uralelectromed is now working on designing a slag processing facility.

The mill reek in 1754

In The mill reek in 1754 Anthony Seaton briefly explores the dust, smoke, and lead poisoning caused by lead refining in industrial Scotland during the Enlightenment.

Mineralogical and Chemical Characteristics of Slags from the Pyrometallurgical Extraction of Zinc and Lead

The slags derived from the fire refining of lead bullion, differ distinctly in the mineral composition, which results from the fact that these slags are end products of a series of chemical reactions (of both reduction and oxidation). The most common phases included in the refining slags are sulphates and hydrated sulphates (anglesite, gypsum, ktenasite and namuvite), oxides and hydroxides (wustite and goethite), nitrates (gerhardtite) and silicates (kirschsteinite and willemite). The other phases are sulphides and hydrated sulphides (sphalerite and tochilinite), metals (metallic Pb) and glass. Among the mineral components of these slags can be distinguished—primary mineral constituents, phase constituents formed in the ISP process and lead refining, secondary mineral constituents, formed in the landfill. The slags contain, in chemical terms, mainly FeO, CuO and SO3, PbO, in smaller contents SiO2, Al2O3 and CaO, TiO2, MnO, MgO, K2O, P2O5. The mineralogical and chemical composition indicate that slags may be a potential source of metals recovery and pyrometallurgical processing of these wastes seems to be highly rational.

Preparation of Calcium Stannate from Lead Refining Dross by Roast–Leach–Precipitation Process

Lead refining dross containing plenty of tin and other heavy metals, such as lead and antimony, is considered a hazardous waste generated in large quantities in lead smelter plants. In this study, calcium stannate was synthesized from lead refining dross using sodium carbonate roasting and alkaline leaching followed by precipitation with CaO. The effect of roasting and leaching parameters on the extraction efficiency of tin was investigated. The leaching efficiency of tin reached 94% under the optimized conditions: roasting with 60% Na2CO3 at 1000 °C for 45 min, and leaching using 2 mol/L NaOH solution for 90 min at 85 °C and 8 cm3/g liquid/solid ratio. Furthermore, more than 99% of tin in the leaching solution was precipitated using CaO. Finally, XRD, SEM, and ICP-OES analyses indicated that the final CaSnO3 product had a purity of 95.75% and its average grain size was smaller than 5 μm. The results indicated that the developed method is feasible to produce calcium stannate from lead refining dross.