Iron Smelt May 2005

This experiment was not performed by DARC but is a part of the sequence of experiements.  Please contact Darrell Markewitz for more details about this experiment.

Date: May 14, 2005
Location: Wareham, ON
Team:

Leader	Darrell Markewitz
Staff	Neil Peterson John Burton
Recorder	Neil Peterson Vandy Simpson
Charcoal Monkeys	Gus Gissing Ken Cook Sam Falzone

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.

Furnace: Econo Norse, firebrick backed with sand set on plinth, tap arch
    Size: 25 cm x 60 H
    Source: DARC 10/04
    Tuyere: 25 mm ID schedule 40 pipe
       Placement: 20 cm above floor, 5 cm in from wall, angle 20 deg down
    Bellows: electric blower / rotary blower
        Air: inconstant flow
Charcoal: 150 lbs broken hardwood
Consumption: approx 2Kg per10 minutes
Ore: Stelco Taconite - 38 lbs (roasted)

Sequence: ore added about every 12 minutes as small charges .75 - 3 lbs
Duration: about 7 hours (plus preheat)
Result: 21 lb bloom - (not tested)
This represents 45 % yield from roasted ore weight

Smelt site	Darrell setting up	Preheating	Tapping
Adding charcoal	Cutting	Finished bloom

Notes:
- Sucessfull creation of mid sized bloom
- tap slag recycled

Bloom was significantly 'trough' shaped - this a result from changes in the tuyere angle during the smelt. Weight estimate is for the main bloom only, and does not include smaller (walnut sized) fragments. Roughly one third of the mass was cut off while still hot from the smelt. The remaining section weighs 14 lbs.

Considerable trouble was experienced during the early part of the sequence with air delivery. Although checked before storage, the main blower did not work at first attempt. A smaller (less volume) vacumn blower was initially employed. Concern developed that it was not producing enough air volume, so a second hand cranked blower was added in conjunction. The main blower was checked and re-installed to the smelter about hour three.

The use of a packing mixure of roughly 50 / 50 beach sand and rough saw dust proved a mixed blessing. First, gaps in the brick structure were not sealed with clay. During firing, the sawdust element burned, and the heated sand ran like a fluid through the cracks. Continual addition of replacement packing proved necessary.

As it turned out, the pure taconite ore lacked the silica content to provide for the required slag. Normally this would have been a major problem, as the firebrick adds little silica (through melting). In this smelt, the sand from the packing actually added the required silica content to create plentiful slag - required to control the carbon content of the bloom.

One third of the bloom was given to Llyod Johnson. He later consolidated and finished the mass into a workable bar. He reports that the material created was 'nice soft workable iron'.

Time		Event	Measures
			Relative	Absolute	Total
Relative	Elapsed				Charcoal	Ore
-00	00	start preheat with wood splits
-35	35	addition rough charcoal, gentle air blast
-45	45	fill with rough charcoal
12:00	00	timer reset - smelt begins
12:10	10	first measured charcoal	1	4 lbs*	4 lbs
12:20	10	charcoal	2	4 lbs	8 lbs
12:40	20	charcoal	3	4 lbs	12 lbs
12:51	11	seed charge	1	.75 lbs		.75 lbs
		charcoal	4	4 lbs	16 lbs
1:06	15	seed charge	2	.75 lbs		1.5 lbs
1:09	18	charcoal	5	4 lbs	20 lbs
1:32	23	charcoal	6	4 lbs	24 lbs
	26	seed charge	3	.75 lbs		2.25 lbs
1:40		addition of second hand crank blower
1:45		tuyere replaced with copper
***
2:02	30	charcoal	7	4 lbs	28 lbs
		seed charge	4	.75 lbs		3 lbs
2:12	10	charcoal	8	4 lbs	32 lbs
2:17	15	seed charge	5	.75 lbs		3.75 lbs
2:29	17	charcoal	9	4 lbs	36 lbs
	12	seed charge	6	.75 lbs		4.5 lbs
2:44	15	charcoal	10	4 lbs	40 lbs
	15	seed charge	7	.75 lbs		5.25 lbs
2:49	5	charcoal	11	4 lbs	44 lbs
	5	seed charge	8	.75 lbs		6 lbs
2:53	4	charcoal	12	4 lbs	48 lbs
	4	full charge	9	1.5 lbs		7.5 lbs
3:00	7	charcoal	13	4 lbs	52 lbs
3:10	17	half charge	10	.75 lbs		8.25 lbs
3:12	12	charcoal	14	4 lbs	56 lbs
	2	full charge	11	1.5 lbs		9.75 lbs
***
3:23	11	charcoal	15	4 lbs	60 lbs
		full charge	12	1.5 lbs		11.25 lbs
3:31	12	charcoal	16	4 lbs	64 lbs
		full charge	13	1.5 lbs		12.75 lbs
3:38	7	charcoal	17	4 lbs	68 lbs
		full charge	14	3 lbs		15.75 lbs
3:50	12	charcoal	18	4 lbs	72 lbs
		full charge	15	3 lbs		18.75 lbs
3.58	8	charcoal	19	4 lbs	76 lbs
		full charge	16	3 lbs		21.75 lbs
4:11	13	charcoal	20	4 lbs	80 lbs
		full charge	17	2.25 lbs		24 lbs
4:21		first tapping attempt
4:23	12	charcoal	21	4 lbs	84 lbs
		half charge	18	.75 lbs		24.75 lbs
4:26	3	charcoal	22	4 lbs	88 lbs
		full charge	19	3.75 lbs		28.5 lbs
4:36	10	charcoal	23	4 lbs	92 lbs
		full charge	20	2.25 lbs		30.75 lbs
		second tapping attempt
4:44	12	charcoal	24	4 lbs	96 lbs
		full charge	21	2.25 lbs		33 lbs
4:52	12	charcoal	25	4 lbs	100 lbs
		full charge	22	2.25 lbs		35.25 lbs
5:02	10	charcoal	26	4 lbs	104 lbs
		full charge	23	3 lbs		38.25 lbs
5:15	13	charcoal	27	4 lbs	108 lbs
		full charge	24	2.25 lbs		40.5 lbs
5:22	7	charcoal	28	4 lbs	112 lbs
		full charge	25	3 lbs		43.5 lbs
5:32	10	charcoal	29	4 lbs	116 lbs
		full charge	26	3.75 lbs		47.25 lbs
5:43	11	charcoal	30	4 lbs	120 lbs
		full charge	27	3 lbs		50.25 lbs
5:54	11	charcoal	31	4 lbs	124 lbs
		full charge	28	3 lbs		53.25 lbs
6:08	12	charcoal	32	4 lbs	128 lbs
		full charge	29	3.75		57 lbs
6:29		tap slag and recycle		3 lbs
(one charcoal addition may be missing here)
6:34	26	charcoal	31	4 lbs	132 lbs
6:43	11	charcoal	32	4 lbs	136 lbs
6:52	11	charcoal	33	4 lbs	140 lbs
6:59	7	charcoal	34	4 lbs	144 lbs
7:06	7	charcoal	35	4 lbs	148 lbs
7:13		start to dismantle smelter
7:26		bloom removed

NOTES:

All ore charges are based on a 'standard scoop' - taconite weight of .75 lbs
* All charcoal charges are based on a 'standard pail' - weight of 4 lbs
This is estimated weight only, not added into charge total

*** Marks areas were records are suspect