Saturday, May 05, 2012

Production (?) Smelt

Although technically I am past the end date for the OAC Project Grant, one of the things I wanted to include was building a more production type furnace and running a test smelt.

As I had detailed in an earlier post, this furnace would include a number of features 'borrowed' from the furnaces that Lee Sauder has been using recently. (This a nice switch, as had focused primarily on clay construction earlier in my development.)
 The main features of this new furnace are:
use of a copper tuyere 
base area built of fire brick
metal sheathing over the shaft
use of sand / horse manure / clay mix

Layout with dimensionsBefore drying fire.
You can see the layout includes a very deep base area, a total of 28 cm from the centre of the tuyere tip to the hard base. When set up for a smelt, the lower 12 cm or so will be filled with charcoal fines. The furnace also has a much larger tap arch. Taken together, this should allow for possible bottom extraction of the final bloom.

The furnace is set on the upper level of the normal smelting area at Wareham. This does make it a bit tall for top extraction (top of the furnace is chest high on me). The advantage is that the bottom of the furnace is set about 18 inches off the ground, making it easier to work tapping or slag bowl modification.

Furnace interior, showing tuyere tip
This furnace will use the new forged copper tuyere (detailed here). The interior view above was taken before the drying fire was started. You can see the usual insert tuyere position, 5 cm proud of the interior wall and set to 23 degrees down angle. The flat brick seen the bottom is supporting the tap arch at this point (the clay was still damp).

Ore Roasting
Earlier in this week I had spent part of two afternoons roasting up ore. I still have a quantity of 'Jamestown Brown', a water deposited ore from that location in Virginia. A number of years back, a group of us were invited to pick some of this material that lay in a large sand bank at the rear of a rural blacksmith/gunsmith's property. Sheldon Browder & Steve Mankowski (from Colonial Williamsburg) have used this ore repeatedly since with good results.

Late yesterday afternoon and early evening I started preparing the smelting area. I started a gentle drying fire using small wood splits inside the furnace. That process continued for several hours. At the same time I sorted out the work area for today's smelt. As well I continued crushing the ore I had roasted over the last week. The ore does seem a bit 'sandy' to me, with a visible variation in iron concentration and form. At worst this may mean some extra slag tapping, but the new furnace layout should provide for this.

Its looking like I may be running this smelt today single handed. Although I have done this (once!) before, I'm expecting a hard day. Lets hope nothing goes seriously wrong with this new furnace.

Stay tuned...

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February 15 - May 15, 2012 : Supported by a Crafts Projects - Creation and Development Grant

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