Document ZBdYEqzkNQBOXeR1DN6by4eg7

Dust is generated in many foundry proc esses and presents a two-fold problem clean ing to .remove deposits and control at the point of origin to prevent further accumulation Some foundries have found water under pressure or mixed with steam to be a good cleaning agent A combination water and compressed air hose with a special nozzle also does a good job With this method, how ever, workers should wear approved respi rators, see Chapter 19, "Personal Protective Equipment " In any case, water cleaning should not be done during or immediately before melting and pounng These opera tions should be started only after all equip ment has been allowed to dry thoroughly Vacuum cleaning is probably the most satis factory method used for dust removal in found ries, and the special equipment needed is well worth the investment Once dust has been removed, further ac cumulation can be prevented by local ex haust systems which remove it at the point of origin See the discussion m Chapter 36, "Ex haust and Ventilation '' Solvents include many different substances, each of which must be evaluated on the basis of its chemical ingredients Proper labeling, limitations on quantities in use, and other methods of control as detailed m Chapter 37, "Industrial Hygiene," can help minimize the toxic and flammable hazards involved m sol vent use Other materials. Acrolein occurs in foundry operations as a result of the thermal decomposition of core oil Aluminum is not usually a toxic hazard in casting processes, but does present a fire and explosion hazard in dust-collecting systems Antimony is usually an unimportant con taminant in foundry operations Beryllium may produce a typical pulmo nary disease, sucb as reported in one plant casting a 1 percent beryllium-copper alloy Carbon, as sea coal, is a common ingredient of molding sand used for facing Carbon dust may cause anthracosis, which produces characteristic lung shadows in an X ray, but is a relatively harmless condition Carbon monoxide is generated during some cycles in the operation of a cupola Chromium is encountered m stainless steel casting as the element or the oxide Expo sures occur during melting, gate and head burning, and grinding Fluorides, sometimes in the form of cryo lite (sodium aluminum fluonde), are used in the manufacture of ductile iron and magne sium castings Iron oxide fumes and dust are created dur ing melting, burning, pounng, gnnding, weld ing, and machining of ferrous castings Ex posure may be particularly high where man ganese steel castings or oxygen-lancing of the furnace is involved Local exhaust can be used (Fig 33-1) Lead is the greatest health hazard m nonferrous foundnes It forms the oxide in melt ing, pounng, and welding operations Ele mental lead dust is produced in cleaning and machining operations Magnesium dust or chips create senous fire and explosion hazards Physiological effects are confined to a foim of "metal fume fever" from the inhalation of finely divided magne sium Mancanese is usually associated with steel castings and bronze alloys in foundry work and presents no special control problem Phosphorus is used m the production of phosphor-copper Acute cases of poisoning have not been reported and chronic cases are rare The drying of phosphor-copper shot may produce phosphine gas Resins--phenol-formaldehyde and ureaformaldehyde--are used m shell molding and create several hazards The phenol-formalde hyde type contain hexamethylenetetramine ("hex") which is a skin irritant and highly explosive This type of resin also decomposes on heating to give a mixture of phenol and formaldehyde vapors Urea decomposes to give ammonia and carbon dioxide In prac tice, however, vapors from resins are a nui sance, because the concentrations needed to produce toxic effects cannot usually be tol erated by man Resin dust, especially "hex," is highly ex- 901