Iron Production Experiment - June 2006

Date: 10 June, 2006

Location: Vinderheima

Premise: Test drive of a new smelter placement with this one being run by Kevin & Dave.

Experiment Notes - Norse Short Shaft Smelter

The Team:

Leader	Kevin Jarbeau / Dave Cox
Staff	Ken Cook
Recorder	Neil Peterson
Supervisor	Darrell Markewitz

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.

Setting up the smelter two weeks before the smelt.

Main space	Level Bank	Notch poles	Concrete embankment
Finished area	Chopping grass for cob	Packing cob	Checking revetment
Final touches	Jiffy pop!

Time		Event	Measures
			Relative	Absolute	Total
Relative	Elapsed				Charcoal	Ore
0:00	00	addition rough charcoal, gentle air blast
0:15		Smelter Corn put on
0:20		Smelter Corn readt for eating
0:40		Start of graded Charcoal
0:45	5	first measured charcoal	1	4 lbs*	4 lbs
0:54	9	charcoal	2		8 lbs
1:02	8	charcoal	3		12 lbs
1:05		Start heating first charge
1:10	8	Charcoal	4		16 lbs
1:11		Ore	1	.75 lbs*		.75 lbs
1:19	9	charcoal	5		20 lbs
1:22	5	Ore	2	.75 lbs		1.5 lbs
1:30	11	charcoal	6		24 lbs
1:33	11	Ore	3	.75 lbs		2.25 lbs
1:38	8	charcoal	7		28 lbs
1:45	12	Ore	4	.75 lbs		3 lbs
	7	charcoal	8		32 lbs
1:52	7	Ore	5	.75 lbs		3.75 lbs
1:55	10	charcoal	9		36 lbs
2:02	10	Ore	6	.75 lbs		4.5 lbs
2:04	9	charcoal	10		40 lbs
2:12	10	Ore	7	.75 lbs		5.25 lbs
2:14	10	charcoal	11		44 lbs
2:22	10	Ore	8	.75 lbs		6 lbs
2:24	10	charcoal	12		48 lbs
2:31	9	Ore	9	.75 lbs		6.75 lbs
2:35	11	charcoal	13		52 lbs
2:46	11	charcoal	14		56 lbs
		Ore	10	.75 lbs		7.5 lbs
2:53	7	charcoal	15		60 lbs
2:56	10	Ore	11	.75 lbs		8.25 lbs
3:05	12	charcoal	16		64 lbs
	9	Ore	12	.75 lbs		9 lbs
3:12	7	Ore	13	.75 lbs		9.75 lbs
3:14		Turned Air up to C+
3:15	10	charcoal	17		68 lbs
3:24	9	charcoal	18		72 lbs
	12	Ore	14	.75 lbs		10.5 lbs
3:35	9	charcoal	19		76 lbs
3:36		Turned Air up to D
3:47	12	charcoal	20		80 lbs
	23	Ore	15	.75 lbs		11.25 lbs
3:48		Optical Pyrometer measurements (2400-2800F)
3:56	9	charcoal	21		84 lbs
		Ore	16	.75 lbs		12 lbs
4:03	7	Ore	17	.75 lbs	84 lbs	12.75 lbs
4:05	9	charcoal	22		88 lbs
4:14	9	Ore	18	.75 lbs		13.5 lbs
		charcoal	23		92 lbs
4:24	10	Ore	19	.75 lbs		14.25 lbs
		charcoal	24		96 lbs
4:33	9	Ore	20	.75 lbs		15 lbs
		charcoal	25		100 lbs
4:42	9	Ore	21	.75 lbs		15.75 lbs
		charcoal	26		104 lbs
4:50	8	Ore	22	.75 lbs		16.5 lbs
		charcoal	27		108 lbs
4:58	8	Ore	23	.75 lbs		17.25 lbs
		charcoal	28		112 lbs
5:06	8	Ore	24	.75 lbs		18 lbs
		charcoal	29		116 lbs
5:14	8	Ore	25	.75 lbs		18.75 lbs
		charcoal	30		120 lbs
5:23	9	Ore	26	.75 lbs		19.5 lbs
		charcoal	31		124 lbs
5:32	9	Ore	27	.75 lbs		20.25 lbs
		charcoal	32		128 lbs
5:39	7	Ore	28	.75 lbs		21 lbs
		charcoal	33		132 lbs
5:46	7	Ore	29	.75 lbs		21.75 lbs
		charcoal	34		136 lbs
5:54	8	Ore	30	.75 lbs		22.5 lbs
		charcoal	35		140 lbs
5:59	5	Ore	31	.75 lbs		23.25 lbs
6:03	4	Ore	32	.75 lbs		24 lbs
	9	charcoal	36		144 lbs
6:07	4	Ore	33	.75 lbs		24.75 lbs
6:12	5	Ore	34	.75 lbs		25.5 lbs
	9	charcoal	37		148 lbs
6:15	3	Ore	35	.75 lbs		26.25 lbs
6:20	5	Ore	36	.75 lbs		27 lbs
	8	charcoal	38		152 lbs
6:24	4	Ore	37	.75 lbs		27.75 lbs
6:26	2	Ore	38	.75 lbs		28.5 lbs
6:29	3	Ore	39	.75 lbs		29.25 lbs
	9	charcoal	39		156 lbs
6:34	5	Ore	40	.75 lbs		30 lbs
6:36	7	charcoal	40		160 lbs
6:39	5	Ore	41	.75 lbs		30.75 lbs
6:42	3	Ore	42	.75 lbs		31.5 lbs
6:44	2	Ore	43	.75 lbs		32.25 lbs
	8	charcoal	41		164 lbs
6:48	4	Ore	44	.75 lbs		33 lbs
6:50	2	Ore	45	.75 lbs		33.75 lbs
6:52	2	Ore	46	.75 lbs		34.5 lbs
	8	charcoal	42		168 lbs
6:54		Gromp	1	nodule
6:56	4	Ore	47	.75 lbs		35.25 lbs
6:58	2	Ore	48	.75 lbs		36 lbs
	4	Gromp	2
7:00	8	charcoal - switch to rough crushed	43		172 lbs
	2	Ore	49	.75 lbs		36.75 lbs
		Gromp	3
7:02	2	Gromp	4
7:04	4	Ore	50	.75 lbs		37.5 lbs
	2	Gromp	5
7:08	4	Ore	51	.75 lbs		38.25 lbs
		Gromp	6
7:10	10	charcoal	44		176 lbs
	2	Ore	52	.75 lbs		39 lbs
		Gromp	7			3.75 lbs
7:19		charcoal	45		180 lbs
7:30		charcoal	46		184 lbs
7:31		Shock Charge - ore	53	.75 lbs		39.75 lbs
7:37		charcoal	47		188 lbs
7:49		charcoal	48		192 lbs
7:55		Turn air down to C
		Scoop out charcoal
7:59		Turn air down to A
8:02		Compacting the bloom
8:06		Extraction
8:12		Removed Tap arch

NOTES:
Charge times recorded at END of unit addtition

* All charcoal charges are based on a 'standard pail' - weight of 4 lbs
All ore charges are based on a 'standard scoop' - weight of 3/4 lbs
An ore scoop was weighed as 410g ( 0.9 lbs), then bags of 10Kg of ore were scooped out and the number of scoops counted - this averaged out to 363g ( 0.8 lbs)
Estimated from known marks

Air flow rates were check at the end of the experiment and confirmed to match previous readings.

YIELD: 8.1 Kg ( 17.8 lbs) in various types

Two small blooms were recovered 900g and 650g.  These seem to be masses with mild steel and cast iron.
An additional 3.75 Kg in a single Cast Iron / Slag mass
600 g of magnetic bits were screened from the ash
1.3 Kg of cast iron were recovered
900 g of loosly sintered material was also pulled from the smelter

This smelt did not work as expected.  Usually around 2.5 hours into the smelt the reaction "takes off".  The time to burn down a bucket of charcoal drops below 8 minutes.  To counter this more ore is added to each bucket of charcoal.  This time this did not happen.  The burn rate stayed at around 8 minutes.  We checked the air flow, which was as expected.  We used the optical pyrometer to check the inside temperature.  6 different readings were tken by various people all in the expected range.  Yet the only difference between this smelt and the previous one was that this smelter was cut into the bank.

Around 6 hours into the smelt it was decided to try increasing the amount of ore in a bucket.  We expected that this would slow down the burn time but we did want to see what would happen.  In a strange twist the burn time stayed at 8 minutes.... so we added more ore, and the burn time stayed at 8 minutes. Given this strange behaviour we finished the smelt as we normally would have.  When the bloom was pulled it was found to be mostly cast iron.  This makes sense as the ore/charcoal ratio in this smelt was much smaller than usual, the ore spent more time in contact with the carbon then would normally happen.

Pictures

Shot down the tuyere	Tapping

There is also a movie of the tapping.

The smelt

Watching charcoal burn	Burning charcoal	Burn baby burn!	Ground forge
Adding charcoal	Overview	Waiting	Ketill listening
Adding ore	Beginning tapping	Slag

Pulling and working the bloom

First few strikes	Notice the chunks?	Working a smaller piece	Finishing touches
Working second piece	Cast iron boiling	Empty Smelter

The Next Day

Encrusted wall	Smelter with no fill	Some cracks	Large crack
Cleanup	Cast iron bits	Bloom with good steel	Two bloom chunks

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.