The Shop > Metal Stuff
New lining for the iron furnace
PekkaNF:
Funny thing. Here the winter has been fluctuating too...Few days -22C etc. Then in less than 20 hours swing to +3C and then alternating order -3/+3 cold nights and snow or rain. Pretty icy roads here. Today on a little cold but snowed 10cm over glass smooth icy roads. We also got super cooled rain at -7C. It froze right when droplets hit anything solid -like road or windshield.
Looks like casting season happens on winter.
vtsteam:
yes Pekka, it's been a weird winter. Today I woke to 8" snow. Plowed for 2 hours on the '51 John Deere M, and it turned to icy rain while I was half way through. I was soaked.
Anyway back to the iron furnace -- I'm just trying to dry the greensand out. I've got a tub of it indoors (with permission!) and though the inside humidity is in the 30's % it is taking forever to dry out. It's been 3 days and nights in an open container with me stirring it up every once in awhile, and it's still very wet. I even tried frying a couple panfuls on top of the wood stove, and they also were unusually slow to give up moisture. This is 60 mesh ceramics grade silica sand, with bentonite in it -- it's only been used a couple times to cast iron. I think the bentonite may be holding the moisture in.
It's different feeling than the aluminum sand I've used for the last 20 years. That stuff was cheaper sandblasting sand mixed with hawthorn fire clay, 3 to 1. The aluminum sand dries quickly and has a good fluffy feel to it, and it squeezes by hand into a nice packed shape that shows good clean breakage.
The iron sand seems different, and I think that may be due to the bentonite. It feels sticky in the hand but it doesn't seem to pack as well and breaks more easily and not as cleanly. Of course it's hard to judge now since it's also too wet.
well time will tell, once I get this stuff dry enough.
EDIT: I was curious so I went back and checked out my original sand and bentonite mix proportions. I was intending 7.5% bentonite, but on recalculating the actual weight I mixed into 50 lbs of sand, I actually added 7% (3.75 lbs). I'd need another 1/4 pound to bring it to 7.5%. So I'll probably add that as soon as I can find where I put the bentonite (!) That also will help dry the mix just a little....
awemawson:
Steve,
When I 'over egged' the water in my greensand once and wanted to loose the excess reasonably quickly I set it churning in a cement mixer, and left a large gas burner burning pointing where the sand was tumbling. Well to begin with it was slurping, but started tumbling as it dried out !
No doubt a fan heater would do a similar job.
vtsteam:
I'm afraid the concrete mixer is just not going to be practical in this weather -- no indoor shop large enough for it. And apparently we won't get above freezing for a week and lots of wind. Arctic air on the menu for the foreseeable future. So no iron casting either. I guess the sand will dry by itself before I'm likely to need it. Not happy about any of that. :bang:
Come on February! :dremel:
mattinker:
Steve,
--- Quote from: awemawson on January 15, 2022, 03:11:25 AM ---Steve I used to use the Zircon as a foundry tool dip years back. Things like stirrers and degassing plungers. It was a white thin paste that I diluted with water. May still have a dried out tub!
It set hard with heat but was liable to flake off and not very durable so I’m surprised it’s suggested as a liner on the Kaowool. Sodium silicate syrup will I’m sure slightly soak in and set rock hard and be more suitable.
I’ve got the sodium silicate but not sure if I’ve any bits of Kaowool left over, if I have I’ll do an experiment.
--- End quote ---
I used sodium silicate on the ceramic fibre in my 200 litre oil drum kiln,it's holding up reasonably well.
I found a recipe for a kind of home-made ITC100 Silicate de Zircon 70% Kaolin 30%. I plan to try it on my next foundry project.
Cheers, Matthew
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