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Iron Smelt - OABA - CanIron VIII, Fergus, ON - July 28,2011

Date:July 28,2011

Location:OABA - CanIron VIII, Fergus, ON

See also: Darrell Markewitz's ironsmelting site

Team: Neil Peterson, Richard Schwietzer, Dave Cox

Premise: Teach blacksmiths to smelt

Furnace Design

TypeEconoNorse in a can (enclosed fire brick), tap arch
Extractiondismantled
Diameter25 cm
Height85 cm
Volume41703.125 cm3
Tuyure Typeceramic tube
Tuyere height from base20 cm
Tuyere penetration into furnace2 cm
Tuyere angle22 deg
Base designnatural set base cm

Burn Details

Bellow Typeblower
Avg Air rateunknown litres per minute
Total Charcoal Mass46 Kg
Avg Burn rate min per 2 Kg
Ore TypeDD1
Total Mass of Ore22 Kg
Burn Duration5.5 Hours

Results

Mass of Bloom5 Kg
Bloom Typehigh carbon
Yield22%
Notesnice soft workable iron

Smelt_cd Reports of all of our iron smelting efforts along with more articles and information are available on the "Iron Smelting in the Viking Age" CD from the Wareham Forge.  Copies of the CD can be purchased here.

Discussion:


This smelt was rather amusing. For 90% of the smelt things seemed to go along just fine. At two points we did get some "burbling" from the airflow and needed to tap. But things were so mellow Richard even had time to try (and fail) at making a bead with the tap slag. We had the chance to show many folks what was going on by offering tours of the view down the airpipe. What we didn't know was that the bloom had formed off to the side and the slag bowl had formed quite high.

Each time we tapped it re-sealed much more solid leaving us at a point where we needed to tap again but couldn't get it to tap. We tried from the sides, we tried pulling out the fines in the base but we couldn't get anything through the base of the slag bowl. We even tried running a rod down from the top to poke a hole straight down, but only managed to weld the rod onto the bloom, which led to some funny comments when we extracted.

This inability to execute a third tap meant we needed to finish early in order to not lose the airflow and have everything freeze. We dragooned a couple of blacksmiths to hammer for us, and grabbed Darrell who was ordered to pull the bloom as we freed things up. We then knocked down the smelter - even though there was still charcoal and ore in the stack. 4 Kg of ore was in the stack but not yet down to the bloom when we opened.

The opening and extraction went well sending the bloom over for a good consolodation. Our efforts to keep a forge going in the smelter didn't go so well as the tuyure was nearly frozen off. We did keep things hot enough that we could keep the bloom very warm until another forge could be prepared (it was nice being at a blacksmith's conference!). When another forge was ready we walked the red-hot bloom over to it. At that forge they consolodated again, then cut it into quarters. One quarter was then further worked until it was ready to use in the blademaking workshop.



Conclusions:


Overall set up
As usual this setup roved its worth. It took less than an hour to set up, Less than an hour to pre-heat. Then a simple straight forward 5 hour smelt - until the hassle at the end. Without that problem we would have had no issues in finishing off the smelt as planned. Even with the problem it produced a very nice little bloom.
Reaction to problems
Again this smelt proved the need to react FAST when problems crop up. We did react fast enough to save the bloom. We also reacted fast enough to save the smelt - it is just that our efforts to fix the problem failed. By reacting fast we actually had time to try different methods to save it one of which might have worked. If we had delayed our reaction we would not have had that opportunity.
Planning for failure
A little fine tuning on the plinth design leaving more accessable openings would have allowed us more opportunities to move the base and perhaps succeed on a tap.


Photos:

(copyright David Daciw)
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Dr. Ross looking for more charcoal to smashSmelter 2nd layerFurnaceTapping slag
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Pulling bloomCompacting bloom

Raw Data:



TIME EVENT ORE CHARCOAL AIR
REL. ELAP. ADD
(scoops)
AMT
(Kg)
TOTAL
(Kg)
ADD
(buckets)
AMT
(Kg)
TOTAL
(Kg)
SET. VOL.
(litre/min)
  0 Switch to graded charcoal              
  1205       X 2 2    
7 1212         X 2 4    
7 1219         X 3 6    
  1229   X              
21 1230 It is likely a bucket of charcoal was missed here       X 4 8    
  1233   X              
  1237   X              
12 1242   X     X 5 10    
  1243   X   1          
  1249   X              
11 1253   X     X 6 12    
  1256   X              
  1303   X   2          
  1304   X              
13 1306   X     X 7 14    
  1313   X              
10 1316         X 8 16    
  1317   X   3          
  1319   X              
  1325   X              
12 1328         X 9 18    
  1329   X              
  1337   X              
16 1344   X   4 X 10 20    
  1345   X              
  1350   X              
  1351   X              
11 1355   X   5 X 11 22    
  1359   X              
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  1401   X              
  1404   X   6          
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15 1410   X     X 12 24 9  
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14 1424         X 13 26    
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12 1608   X     X 22 44    
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13 1657         X 26 52    
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  1703   X   26          
  1703   X              
Smelt_cd Reports of all of our iron smelting efforts along with more articles and information are available on the "Iron Smelting in the Viking Age" CD from the Wareham Forge.  Copies of the CD can be purchased here.
Text © Darrell Markewitz, 2011   Photographs © Darrell Markewitz   Copyright details
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