Production of Active Lead(II) Oxide by the Wet Milling Method under Pressurized Oxygen

Abstract

A new production method of lead( II) oxide by means of the oxygen pressurized wet milling method was proposed. In the method, surfaces of spherical granules (3-5 mm in diameter)of metallic lead were oxidized by the gaseous oxygen in the presence of water at a temperature below about 60°C in the rotary mill. The formation rate of lead(II) oxide was found to be controlled by the diffusion of oxygen in the thin layer of water over the surface of metallic lead granule. Under the conditions of high contact efficiency of these three phases-oxygen, water and lead surfaces-and rapid diffusion of oxygen in the water phase, the formation speed of lead(II) oxide was remarkably increased.
Three kinds of lead(II) oxides, i. e., massicot (orthorhombic), litharge (tetragonal) and 3 PbO·H₂O (tetragonal) were produced depending on the conditions. The particle sizes of these lead( ff ) oxides were much smaller than those of the lead(II) oxides obtained by the dry method. It was also found that these lead( II) oxide were very active in the reaction with CrO₃ and showed other excellent properties as are summarized in Table 2.