Iron oxide dust

Case Study. Such a situation was found to occur in the duct network shown in Fig. 21 and installed to extract iron oxide dust at various points along a cold strip processing line. The stated problems were insufficient suction at the hoods, buildup of contaminant in the hoods and along the processing line (causing cleanup problems due to eventual mixing with hydraulic fluid, lubricant, water, etc.). Analysis of the system found the following ... 

Figure 21. Duct network for extraction of iron oxide dust.

For example, for the iron oxide dust considered in the previous case study, Table 2 suggested Vfmm = 18 to 20 m s1 (i.e., assuming an average industrial dust ) On analysis of the sample, it was found dp50 80 pm, which appeared to support this classification. However, upon further examination of the actual distribution of size, a significant proportion of the material was found > 1000 pm (e.g., large flakes). A minimum conveying velocity of at least Vjmm 25 m s 1 was estimated for this dust. This explains why the iron oxide material built up and eventually blocked branch II-IV, which was sized/balanced mainly for air distribution purposes and produced transport velocities < Vfi r... 

McLaughlin AIG, Grout JLA, Barrie HJ, et al. 1945. Iron oxide dust and the lungs of silver finishers. Lancet, March 17, 337-341. 

ACGIH TLV TWA 5 mg(Fe)/m3 (vapor, dust) Not Classifiable as a Human Carcinogen Rouge 10 mg/m Not Classifiable as a Human Carcinogen DFG MAK 1.5 mg/m3 calculated as fine dust NIOSH REL (Iron Oxide, Dust and Fume) TWA 5 mg/m3... 

The ACGIH threshold limit value, 8 h time-weighted average, for iron oxide dust and fume is 5mgm. The Environmental Protection Agency s Federal Drinking Water Guideline for iron is 300 pgH. ... 

SPILL CLEAN-UP carefully sweep up iron oxide dust and remove if appropriate, moisten first to prevent from dusting wear suitable protective clothing during clean-up procedures. 

Where the amine is recovered by vacuum distillation directly from the iron oxide, steel or cast-iron stills with heavy plow agitators are used. They may be heated by means of hot oil or Dowtherm. A column equipped with baffle plates is employed to prevent entrainment of iron oxide dust. 

The only two waste streams generally susceptible to joint treatment ate the coke oven wastewaters (ammonia liquor, still bottoms, and li oil recovery wastewaters) and the pickling liquor. The oAer process wastewaters are high in solids (sub-micron iron oxide dust) and heavy metals. Pretreatment to reduce these waste constituents generally results in an efiluent vidiich can be discharged directly to surface waters. 

Iron oxide—Siderosis, fibrosis caused by iron oxide particles, is a form of pneumoconiosis. The ACGIH TLV-TWA for iron oxide dust and fume is 5 mg/m (ACGH 1998). 

Originally, iron powder from mill scrap was used in powder metallurgy. The soap was primarily iron oxide that would fall off the steel as it was being milled. The iron oxide dust was heated in a hydrogen atmosphere to reduee the oxide to iron particles. Manufacturers called the powdered metal iron sponge because numa-ous holes form in the particles when the oxygen escapes. 

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