Iron Smelt Vinderheima 2006

Date: 5 November, 2006

Location: Vinderheima

Premise: Explore an interesting result from Early Iron 3 - that ore can be added very much faster than we have done in the past.

Experiment Notes - Norse Short Shaft Smelter

The Team:

Leader	Darrell Markewitz
Staff	Kevin Jarbeau Ken Cook Darrell Markewitz
Recorder	Darrell Markewitz Neil Peterson

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.

Smelt Totals

Total Charcoal	42 lb (19 Kg)	Weight of Bloom		Total Elapsed Time:	2:48 to last charcoal added
Total Ore	47 lb (21 Kg)	Weight of Slag:		Bloom Quality

Discussion:

This smelt simply re-used the existing smelter, patched it in minor ways, and did a new smelt.  The difference being a planned ratio of nearly 1:1 ore/charcoal.

It didn't work.

Some of the problems.  

• We changed charcoal.  We had run out of the Royal Oak so we tried some from a different supplier.  This charcoal was considerably drier and hence lighter.  We didn't discover until the end that the 4lb bucket we were using weighed (with the new charcoal) more like 2-2.5 lbs.  This meant that we were adding 3.25lbs of ore to 2ish lbs of charcoal instead of the planned 4lbs of charcoal.  This meant that the ore wasn't being heated as much.
• The base was not set up with fines to position the bloom in the right spot (this is believed to be the cause of the failure - and was confirmed by Darrell repeating the smelt the next day with this fixed - that smelt worked.) The base was allowed to establish itself from the collected wood ash from the pre-heat, plus addtiional charcoal. This resulted in the slag bowl forming significantly lower than what had been seen in the past. (roughly 10 plus cm below the bottom of the tuyere.)
• The ore scoops weren't the 0.75 lbs we were used to - they were more like 0.9lbs.  We are going to have to get into the habit of re-calibrating at EVERY smelt to allow for variablility in raw materials.

Fun none the less and a lovely day for a smelt.


Our images didn't turn out well due to a small technical glitch but here are four interesting shots.

Smelter with extension	Burning	Burndown	Slag

And four more attempts at a "down the pipe" shot.  These shots are taken down the tuyure through the clear cap on the end.  I am currently using a manual focus 200mm lense with two ND0.6 filters to decrease the light level.  Even at 200mm the portions below occupy a space less than 2" square on the 4x6 print.  The apature is around f11, the internal light meter is suggesting around a 1/30 second exposure.  These are actually shot at 1/1000th and are still a little saturated.  Next time I want to pre-focus the camera at a target inside the smelter before the pre-heat.  My camera guy is also looking for a lense adapter which will jump the lense to a 400mm and knock of two more stops to allow me more freedom in choosing exposures.  Should be fun....

Burning charcoal	Blockage	Down the pipe	Down the pipe

ELAPSED;	COMPARE	EVENT	ORE				CHARCOAL		AIR
			ADD (scoops) (410 g)	AMOUNT (Kg)	TOTAL (Kg)	COMPARE (LB)	TOTAL (1 Kg each)	COMPARE (LB)	SETTING	VOLUME (litre/min)
		start preheat
40		addtion of rough carcoal							B	700
10									D	1060
5		start graded fuel
0							1
4							2
6							3
7							4
5		burn column to top of clay					5
8		start of ore charges	5	2	2		6
7	15		5	2	4	8.8	7	4.4
7			5	2	6		8
4	11		5	2	8	8.8	9	4.4
8			5	2	10		10
5	13	first ore hits tuyere?	5	2	12	8.8	11	4.4
7		rod tuyere	5	2	14		12
6	13		5	2	16	8.8	13	4.4
7			6	2	18		14
5	12		6	2	20	8.8	15	4.4
6		last ore charges	2	0.8	20.8		16
6							17
8							18
7		start burn down					19
31		start emptying furnace							B	700
		TOTALS	LBS		47		42
			KG		21.00		19.00

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.