Fettling

Emission levels from the exhaust gas of fettling have been collected in an Italian foundry survey. The results are displayed in Table 3.55. All techniques achieve dust emission levels below 30 mg/Nm The bag filter and Venturi allow maximum levels below 10 mg/Nm. The wet multi-eyelone is the least effective system, leaving an emission factor well above those for other teehniques. The emission factor is largely dependent on the amount of finishing needed and thus the type of castings made. 

Emission factor data in g/tonne of good casting and for cleaned gas  

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Fig. 14.4. Sand casting. When the casting has solidified it is removed by destroying the sand mould. The casting is then "fettled" by cutting off the ingate and the feeder head.

Besatz, m. border, edging, trimming (Metal.) fettling charge (of a crucible) stemming, tamping. 

Tetragonal holohedra from acetone + alcohol, mp 140. dj° 1.773. Soluble in acetone. Practically insoluble in water (1.5 -> / ml) Sparingly sol in alcohol, ether. Does not reduce Fettling s soln (difference from erythrityl tetranitrate). Caution Explodes on percussion. More sensitive to shock than TNT. For medicinal purposes it is dil with an inert ingredient, usually lactose, to prevent accidental explosions. 

Dead-burned dolomite is used in the production of refractory bricks, shaped refractories and for monolithic refractories. High purity, low iron dolomite for brickmaking is generally sintered at temperatures of 1800 °C or higher (see section 16.9). A lower purity product (which is often pre-blended with 5 to 10 % of iron oxide to assist sintering) is used for fettling purposes. It is sintered at 1400 to 1600 °C. 

Mifs M. E. Jackfon acquainted me, that fhe witneffed this autumn an agreeable inftance of fagacity in a little bird, which feemed to ufe the means to obtain an end 5 the bird repeatedly hopped upon a poppy-ftem, and fhook the head with its bill, till many feeds were fcattered, then it fettled on the ground, and eat the feeds, and again repeated the fame management. Sept. I, 1794. 

For these reasons, it is often beneficial to coat the mould or the core with a refractory lining, in order to give a smooth surface finish to the casting and to reduce fettling cost. 

Table 3.55 Emission data for the exhaust gas from fettling, using various dedusting techniques, [180, Assofond, 2002]...

Wet scrubbers and fabric filters have been installed and operated successfully for many years. Fettling cabins with high-efficient dust arrestment units can be run stackless, as their output is cleaner than the usual fettling shop air. They also help to improve workplace conditions. 

Operational data is given in Section 3.11 and show that emission factors for cutting, scarfing and welding (without off-gas cleaning) are low, as compared to those for fettling and shot... 

For abrasive cutting, shot blasting and fettling, BAT is to collect and treat the finishing off-gas using a wet or dry system. The BAT associated emission level for dust is 5 - 20 mg/Nm The techniques for off-gas collection and exhaust air cleaning are discussed in Section 4.5.10.1 and 4.5.10.2. 

In the discussion on the re-use of dust and residues, no information was provided on treatment or re-use techniques for dust from induction furnace melting, for dross from aluminium melting, fettling dusts, abrasives or for blasting grit, although a re-use of most of these materials into secondary metal production is possible. 

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