Pre-industrial Iron Symposium                           October 10, 2004                  Experiment Notes - Viking Age Smelter

 

Bellows :     Michael Mahoney

                  Millard Wyman

                  Paul Bourdon

Recorder :  Elizabeth Hendrix

Leader :      Darrell Markewitz

 

TIME                                         EVENT                                                                           MEASUREMENT                                                              

Realative  Absolute  Elapsed                                                                                          Relative                   Absolute                  Total      

 

2:00 pm                                   slow preheat with split soft wood fire

3:45           1:45                       prep of bellows (attached to tuyere)

3:50           1:50                       start of bellows, split soft wood - various users           +/ - 60 /min            120 l/min

4:17           2:17                       end of pre-heat phase

 

4:17                                         fill furnace with prepared charcoal                                air : 60/min          130 l/min

                                                                                                   fuel: 60 cm           36900 cc                  37 l

4:32           0:15        15 min     add charcoal                                                                 air : 60/ min         130 l/min

                                                                                                                                    fuel : 10 cm            6150 cc                  43 l

4:37                          17 min     bellows operator changed                                                                                                                    

4:42           0:25                       optical pyrometer reading                                                                             2720 F

4:44           0:27        12 min     add charcoal                                                                 fuel : 10 cm          6150 cc                  49 l

4:48           0:31                       air rate measured                                                         air : 72 /min         160 l/min   

4:53                          16 min     bellows operator changed                                             

4:57           0:40        13 min     add charcoal                                                                 fuel : 10 cm          6150 cc                  55  l

4:59                          6 min       bellows operator changed                                              air : 54 /min         120 l/min

5:07                          8 min       bellows operator changed

5:11                          4 min       bellows operator changed

5:16                          5 min       bellows operator changed                                              air : 60 /min         130 l/min  

                  0:59        19 min     add charcoal                                                                 fuel : 10 cm          6150 cc                  61  l

5:29                          13 min     bellows operator changed                                              air : 72 /min         160 l/min  

 

5:32           1:15                       ore charge (one)                                                           ore :                        1.5 kg                  1.5 kg

                                 16 min     charcoal charge on top                                                  fuel : 5 cm            3075 cc                  64 l

5:41                          13 min     bellows operator changed                                             

5:42           1:25                       optical pyrometer reading                                                                             2660 F

5:44                                         crack in smelter wall patched

5:47           1:30        15 min     ore charge (two)                                                           ore :                        1.5 kg                  3.0 kg

                                                charcoal charge on top                                                  fuel : 5 cm            3075 cc                  67  l

5:53                                         tuyere blocked / cleared with rod

6:01           1:43        14 min     ore charge (three) on rear half only                              ore :                        1.5 kg                  4.5 kg

                                                charcoal charge on top                                                  fuel : 5 cm            3075 cc                  70  l

                                 20 min     change of bellows operator

6:05                                         tuyere blocked / cleared with rod

6:06                                         increase of bellows delivery pressure                           air : 72 /min         160 l/min

6:11                          6 min       change of bellows operator

                                                tuyere blocked / cleared with rod

6:15           1:57        13 min     ore charge (four) on rear half only                                ore :                        1.5 kg                  6.0 kg

                                                charcoal charge on top                                                  fuel : 5 cm            3075 cc                  73 l

                                                                                                                                    air : 60 /min         130 l/min

6:18                                         larger crack in furnace repaired

6:23                          5 min       bellows resumed

6:26                          15 min     change of bellows operator

6:27                                         optical pyrometer reading                                                                             2200 F

6:29                                         tuyere blocked / cleared with rod

6:32           2:14        17 min     ore charge (five) on rear half only                                ore :                        1.5 kg                  7.5 kg

                                                charcoal charge on top                                                  fuel : 7.5 cm         4610 cc                  77.6  l

6:44                          18 min     change of bellows operator

 

6:46           2:28        14 min     charcoal charge added                                                   fuel : 7.5 cm         4610 cc                  82.2  l

6:50                          6 min       change of bellows operator                                            air : 72 /min         160 l/min

6:55                          5 min       change of bellows operator

6:58           2:40        14 min     charcoal charge added                                                   fuel : 10 cm          6150 cc                  88.2  l

7:04                                         optical pyrometer reading                                                                             2680 F

7:12           2:54        14 min     charcoal charge added                                                   fuel : 7.5 cm         4610 cc                  92.8  l

7:20                          25 min     change of bellows operator

7:24                          4 min       change of bellows operator

                  3:06        12 min     charcoal charge added                                                   fuel : 5 cm            3075 cc                  95.8  l

7:29                                         repair of crack in smelter

 

7:30           3:12        6 min       ore charge (reduction fines) added                                 ore :                        .5 kg (350 ml)             8 kg

                                                                                                                                    fuel : 5 cm            3075 cc                  98.8  l

7:40                                         slowing of bellows rate during repair

7:50                          26 min     change of bellows operator,  rate continues slow          

7:53           3:35        17 min     final charcoal charge added                                           fuel : 5 cm            3075 cc                  102  l

 

8:15                          25 min     change of bellows operator, rate continues slow

8:25                          10 min     change of bellows operator,  rate continues slow

8:40           4:05                       end of firing

 

8:40                                         start scooping remaining charcoal from smelter

8:45           4:10        5 min       bloom / slag bowl exposed

8:54           4:19        9 min       bloom / slag mass extracted from smelter

                                                                                                                                   

 

AIR :          Calculated against earlier measurement to fixed volume / note variation by operator                  2.2 l per stroke (average)

FUEL :         Calculated by height at fixed furnace dimension of 28 cm diameter                                              615 cc per cm

ORE :          Total of 17.5 lbs / 8 kg roasted ore was prepared / charges estimated individually by volume  1.5 kg per charge

 

Patching :   Each time a hole / crack was patched, the bellows was stopped for the time required, typically about 2 - 3 minutes

Clearing :   Each time the tuyere was cleared, the bellows was stopped for the time required, typically about 1 - 2 minutes

Operator :  There were a number of people who assisted in bellows operation, especially during the pre-heat phases. There was considerable variation in rate, loft and pressure between these. Typically these are represented by the short bellows operator times. From the begining of the ore charge phase, the three primary operators rotated, delivering a much more consistant and controled rate / loft / pressure.