Oxidized lead dust

The rates of gas-solid reaetions are surfaee area dependent, so finely-divided metals, eoal ete. may be prone to oxidation leading to spontaneous eombustion. A eombustible dust will burn mueh more rapidly than the bulk sold, and if dispersed in air eause a dust explosion (refer to Table 6.2). 

The cast grids are made into battery anode and cathode plates by the application of a lead oxide paste of 70 percent lead oxide (PbO) and 30 percent metallic lead. Lead ingots are tumbled in a ball mill with airproducing lead oxide and fine lead dust (referred to as leady oxide ). Leady oxide particulates are entrained in the mill exhaust air, which is treated sequentially by a cyclone separator and fabric filter. The used fabric filter bags are shipped to a RCRA-permitled commercially operated ha2ardous waste landfill located in Colorado. The leady oxide production process does not produce wastewater. 

The production of the active material for positive and negative electrodes starts with the same substance, a mixture of lead oxide (PbO) and metallic lead called gray oxide or lead dust. It is a fine powder that contains 20-30 wt.% of lead (Pb). The size of the primary particles is in the range of 1-10 /an. Larger agglomerates are usually formed. 

Recent Experimental Results. The agglomerator has performed reliably and the results were quite repeatable. We have used a processed fly ash dust consisting primarily of silica, alumina and iron oxide particles. A typical set of results is shown in Figure 11 for a dust loading of about 2 g/m3 and an exposure time of 10 seconds. The results show that the maximum agglomeration for this density of dust and this particular size distribution does occur near the predicted value of 2500 Hz with clearly less agglomeration at 1290 Hz. Earlier experiments with heavier white lead dust followed prediction and gave an optimum frequency of about 1500 Hz. 

MONOPHENYLHYDRAZINE (100-63-0) A highly reactive reducing agent. Combustible solid (flash point 190°F/88°C). Dust or powder forms explosive mixture with air. Reacts violently with oxidizers calcium hypochlorite, fluorine, hydrogen peroxide, perchlorates methyl iodide, 2-phenylamino-3-phenyloxazirane, 3-(3-cyano-l,2,4-oxadiazol-5-yl)-4-cyanofurazan-2-(5-) oxide, dicyanofurazan, dicyanofurazan-n-oxide, lead dioxide. Mixture with perchloryl fluoride forms an explosive material. Incompatible with oxides of iron. 

TELLURIUM (13494-80-9) Finely divided powder or dust may be flammable and explosive. Violent reaction with strong oxidizers, bromine pentafluoride, halogens, interhalogens, iodine pentafluoride, hexalithium disilicide, lithium silicide, nitrosyl fluoride, oxygen difluoride, sodium peroxide, sulfur, zinc. Incompatible with cadmium, cesium, hafnium, strong bases, chemically active metals, iodic acid, iodine oxide, lead chlorite, lead oxide, mercury oxides, nitric acid, peroxyformic acid, platinum, silver bromate/iodate/ fluoride, nitryl fluoride, sodium nitrate. 

ZIRCAT (7440-67-7) Finely divided material is spontaneously flammable in air may ignite and continue to bum under water. Violent reactions with oxidizers, alkali hydroxides, alkali metals (and their compounds), carbon tetrachloride, cupric oxide, lead, lead oxide, lead peroxide (combined material can burn explosively, and is sensitive to friction and static electricity), nitryl fluoride, oxygen difluoride, phosphoms, potassium, potassium compounds (potassium chlorate, potassium nitrate), sodium borate, sodium hydroxide. Explodes if mixed with hydrated borax when heated. Contact with lithium chromate may cause explosion above 752°F/450°C. Forms explosive mixture with potassium chlorate. Dusts of zirconium ignite and explode in a carbon dioxide atmosphere. Contact with ammonium-V-nitrosophenylhydroxylamine above 104°F/40°C forms an explosive material. Incompatible with boron, carbon, nitrogen, halogens, lead, platinum, potassium nitrate. In case of fire, use approved Class D extinguishers or smothering quantities of dry sand, crushed limestone, clay. 

In principle, a significant reduction in the energy related impact on the environment is being achieved, if non-fossil hydrogen be substituting conventional fuels. There are no emissions of carbon oxides, hydrocarbons, dust or ash, heavy metals, lead compounds, or SO2. Some environmental risks are left concerning, e.g., gas emission during combustion or the establishment of the infrastructure. 

Leady oxide manufacture is potentially very hazardous. It is therefore vital to take adequate measures to minimise, or even eliminate altogether, possible lead dust emissions out to the working environment and thus exposure of the personnel which would cause health problems. This is achieved by the use of a closed (isolated) leady oxide production equipment and transport pipes from the storage silos to the paste mixing unit. Special attention should be paid to file manufacture of tubular battery plates. Until recently, tubular plates were filled with a dry mixture of leady oxide and red lead powders. 

The paste-like lead oxide masses, which are applied on the grids, consist of lead dust (25% dispersed lead and 75% lead oxide (PbO)) produced out of the basic material soft lead. The production takes place in ball mills from the solid state or in reaction containers from the molten state. 

Zinc oxide or zinc white is used in paints, but more preferable, because of its better covering power, is lithopone (a mixture of zinc sulphide and barium sulphate). Both paints have the advantage over white lead that they do not blacken in air (due to hydrogen sulphide). Zinc dust and also zinc chromate are constituents of... 

---