Ceramic and Glass Materials

160 J.M. Schoenung

Primary Lead-containing

Mineral Ores

Crushing and Grinding

Concentration

e.g., Froth f lotation

Dewatering

Extraction

Smelting

Refining

<2mm particles

Mostly PbS, plus metallic

impurities and lime

Pb: 40 - 80% by weight

SO 2 and SO 3

Metal oxides

Pb: 95 - 99% by weight

Ag, Au

Zn

Trace impurities

Bi

Pb: 99.9 - 99.99% by weight

Sb, Sn, As

Heat in Oxidizing

Environment

Heat in Reducing

Environment

Cu Drossing

Fig. 3 Process flow diagram for the concentration, extraction, and refining of lead

pure lead is derived are galena (PbS), anglesite (PbSO 4 ), and cerussite (PbCO 3 ) with
lead concentrations (by weight) of 87%, 68%, and 77.5%, respectively. Galena is easily
recognized in the field because of its characteristic cubic shape, metallic luster, and
high density. Anglesite and cerussite result from the natural weathering of galena.
These three minerals exhibit the rock salt (NaCl), barite (BaSO 4 ), and aragonite
(CaCO 3 ) crystal structures, respectively. The JCPDS cards that describe the crystallographic
characteristics for these minerals are as follows: 05–0592 for galena (PbS), 36–1461
for anglesite (PbSO 4 ), and 47–1734 for cerussite (PbCO 3 ).
After being mined, these lead-containing minerals proceed through a concentration
process that increases the lead concentration and removes waste (non-galena) rock,
which is called gangue. The concentration process generally begins with crushing and
grinding steps that ultimately result in particles <2 mm in size, followed by the actual
concentration step, which is sometimes referred to as “beneficiation.” The most common