A thin hotface medium/low mass beer keg (drum size) furnace for melting Iron

I have not heard about satanite.
Has anyone used it here?

The soft brick may work with the zircon coating, but if it did not, you lose the brick and the coating; a two-fer loss.

A friend came over today, and helped me carry my new furnace outdoors.
It was a bit much for me to lift it as a total assembly.
So now I have it outside and perhaps can start some tests this coming week.

 

Satanite I think is a lot cheaper than ITC100. That's the extent of my knowledge on the stuff.

 

Satanite is not only a powder, after you mix it up you can reconstitute it if it has not been fired. So leftovers you can dry out and reuse later. It has made a nice hard surface on my firebrick. It takes minimal dryout then just fire the furnace. HighTemperatureTools has it, $15 for a 5# bag and $46 for 20#. 5# is quite a lot. I bought 20# and am storing about 18#. My flue is all soft brick and I lined it with Satanite. I was trying to be careful to not wear the brick with tongs and material I'm feeding but the Satanite is so hard I'm getting sloppy and have not damaged it yet. I've got about 100 heats on it.

Here's my furnace, I built it big because I can leave it where it sits. Cold to melt 5# aluminum is about 20 minutes and I can remelt in ten minutes from lighting if I'm quick but it's usually 15 minutes or longer because I'm feeding scrap slowly. http://forums.thehomefoundry.org/index.php?threads/simple-brick-furnace.288/

And here's a Satanite thread with some useful information from other guys, especially fishbonz. http://forums.thehomefoundry.org/index.php?threads/what-i-learned-about-satanite.361/

 

I checked out your furnace build thread.
Somehow I overlooked all that in the blur of work earlier this year; great work, especially on that lid brick bevel cutting; too cool.

Do you have a burner thread?

I have done some very fast aluminum melts with an oil burner.
The furnace basically iron-rated to be used with an oil burner, else it will not last long (not sure about the coated soft fire brick though, never tried with with an oil burner).
But with my oil burner cranked up on high (lets say 3 gal/hr), I melted 20 lbs of aluminum in 12 minutes (cold to pour temperature), and when using my very high mass (perhaps 700 lb) furnace.
For aluminum, you do not have to actually bring the furnace up to its maximum temperature in order to melt the aluminum, which was a surprise to me, since with cast iron the furnace mass does have to come up to a high temperature before the iron will melt (my experience anyway).

The fast aluminum melts work very well because there is not much time for the melt to absorb anything, and so I did not experience any visible poroisity in the AL, and did not de-gass, and did not need to de-gas.

At one time I considered using an oil burner to melt aluminum gross overkill, but there are some advantages to doing so, and if you are doing back-to-back pours of multiple molds, you can really turn out a lot of product in a short time. I did five back-to-back AL pours in perhaps 2 hours or less. Fast melts/pours with a smaller furnace and crucible is a good alternative to having to deal with a large furnace and crucible.

 

Thanks! The lid came out looking good. The ring I made was not round, and the brick were precut for a round ring so the flue opening is irregular. But it lets gas out.

No burner thread. It is shown in post 28. http://forums.thehomefoundry.org/index.php?threads/the-basics-drip-injection-waste-oil-burners.24/page-2
It is incredibly simple, just has a 3/16" brake line to the end of the tube for oil and the propane goes straight in the side. A shop vacuum provides air for propane and oil. I can put in a lot more oil than I can burn.

I'm burning a little over 2 gallons per hour pressurized drip. I start on propane blowing on a wad of burning newspaper and get the furnace red before turning in oil. Then after all the charge is in (for aluminum) I switch back to propane to minimize smoking when I open the firebox to pour.

My 2,600F firebrick get flame impingement and have Satanite on them. I have 70 oil burns on it since May and am seeing no deterioration. It melted copper and brass quickly but I am mostly doing aluminum.

I don't think I could melt 20 lbs in 12 minutes, but I only have a 5 lb crucible.

I am addicted to free fuel and picked up 35 gallons from a local service station after I burned all mine.

 

A few values I have accumulated from the internet:

BTU CHART
3412 BTU/hr = 1 KW

Oil Burner Approximate Values:
1 gal/hr = 138,500 Btu/hr (40.59 kW)
2 gal/hr = 277,000 Btu/hr (81.18 kW)
3 gal/hr = 415,500 Btu/hr (121.77 kW)
4 gal/hr = 554,000 Btu/hr (162.36 kW)

5 gal/hr = 692,500 Btu/hr (202.96 kW)
6 gal/hr = 831,000 Btu/hr (243.55 kW)
7 gal/hr = 969,500 Btu/hr (284.14 kW)
8 gal/hr = 1,108,000 Btu/hr (324.73 kW)

9 gal/hr = 1,246,500 Btu/hr (365.32 kW)
10 gal/hr = 1,385,000 Btu/hr (405.92 kW)
11 gal/hr = 1,523,500 Btu/hr (446.51 kW)
12 gal/hr = 1,662,000 Btu/hr (487.10 kW)

Heat Value of Materials:
#2 Diesel = 138,500 BTU/gal



FLAME TEMPERATURES, FURNACE EFFICIENCIES, HEAT VALUES

Common Flame Temperatures
Acetylene with Air 4532 F
Acetelene with pure Oxygen 6296 F
Natural Gas with Air 3562 F
Propane with Air 3596 - 3623 F
Propane with pure Oxygen 4579 - 5110 F
Wood 3596 F
Kerosene 3810 F
Light Fuel Oil 3820 F
Medium Fuel Oil 3815 F
Heavy Fuel Oil 3817 F
Coal 3950 F approx.

Standard propane torch 2,012 F

Air = 21% oxygen

Furnace Efficiencies
Crucible (gas) 7-19%
Cupola 40-50%
Dirct Arc 35-45%
Induction 50-70%

Heat Value of Materials
#2 Diesel 138,500 BTU/gal
Kerosene 135,000 BTU/gal
Natural Gas 100,000 BTU/therm
Propane 92,5000 BTU/gal
Sawdust (green) 10,000,000 BTU/ton
Sawdust (dry) 18,000,000 BTU/ton
Electric 1.0 kWh = 3,412.14 Btu

Miscellaneous
1KWH = 1 kilowatt operated for a 1 hour period
1 BTU = 0.000292071 kWh


FERROSILICON
Add approximately 0.75 oz per pound of iron (check me on this value, but this is what I have been using).

 

CRUCIBLE TEMPERING

Here is some data from Morgan. Note that the clay-graphite Salamander Super is "ferrous-metal-rated", and the silicon-carbide Excel and Himelt are designed for non-ferrous metals with lower casting temperature ranges.

A Morgan "SALAMANDER SUPER" is a graphite crucible.
It can be used with both ferrous metals such as gray iron, as well as non-ferrous alloys such as aluminum, brass, and bronze.
Typical metal casting temperatures are 1562 F - 2912 F (850 C - 1600 C).
Color is black.
The PREHEATING / FIRST USE instructions for fuel-fired furnaces is as follows (per Morgan):
A new crucible shold be preheated empty in order to minimize the termperature gradient across the crucible wall. If there is a risk of the crucible having absorbed some moisture, then the furnace should be initially heated slowly up to approximately 392 F (200 C) and held at this temperature until all moisture has been driven off.
A new crucible should initially be heated slowly and evenly to 1112 F (600 C) on low power, avoiding local impingement of flame on the crucible. Subsequently the full heat input rate should be utilized to achieve a uniform bright red condition over the whole crucible at approximately 1650 F (900 C) at which point the crucible should be charged immediately, taking care not to packing metal tightly or bridging ingots across the crucible.

Morgan "EXCEL" and "HIMELT" crucibles are made from silicon carbide, and are designed for use with non-ferrous metals (not iron).
Typical metal casting temperatures for these crucibles are:
EXCEL: 1562 F - 2882 F (850 C - 1250 C)
HIMELT: 1830 F - 2550 F (1000 C - 1400 C)
The color is red.
The PREHEATING / FIRST USE instructions for fuel-fired furnaces is as follows (per Morgan):
A new crucible shold be preheated empty until they reach a uniform bright red color (approximately 1650 F (900 C) in order to pre-condition the glaze. The preheating time will depend o the size of the crucible (can be up to one hour for a large crucible). Avoid direct flame impingement on the crucible surface.

 

ITC-100 questions

How do I mix and apply ITC-100?

For ITC-100, the manufacturer recommends to mix it 2:1, so if you have a pint, mix it with a half pint of water. My experience, indicates that mixing it a little thinner is just as good if you are using Satanite as a basecoat first. Since you're using the Satanite as a protective coating, the ITC-100 doesn't need to serve this function. Mix it thin, and apply the coats evenly. Applying several thin coats is better than applying a single thick coat. You'll likely have some left over for future patching. Apply the ITC-100 over the Satanite only after the Satanite is fully cured. You can use ITC-100 alone without first applying Satanite, you will just need to use more of this material.


I purchased my ITC-100 a while ago and haven't used it yet. It is starting to dry out, is this a problem?

While most refractory materials come in dry form, ITC-100 comes partially pre-mixed in a clay consistency. If your ITC-100 is starting to dry out you can store it in an air tight container if you like. Just add water to get it back to its original consistency.


How much area will ITC-100 cover in a forge?

ITC-100 will cover 6 to 12 square feet per pint, or 3 to 6 square feet per half pint. If you apply a basecoat of Satanite to your forge first, you can get by with the larger number for square feet coverage. An additional benefit to doing this with Satanite first, is that Satanite is cheap and by building up a 1/4" layer of Satanite over you Inswool liner before applying the ITC-100 your forge will be more robust.



ITC-213 questions

What is ITC-213 used for?

ITC-213 is made to protect metals and graphite, including those exposed to molten metals. It helps to prevent steel and stainless steel parts from erosion, oxidation and fatigue from prolonged use. It can also be used to protect forge burner nozzels, pipe crucibles and electric heating elements.

How do I mix the ITC-213?

You mix it 3:1 with water, thus, if you have a pint of ITC-213, you would add 1/3 pint of water.

How much surface area will ITC-213 cover?

A pint of ITC-213 will cover 18 to 30 square feet. A half pint will cover 9 to 15 square feet.

 

Castable Refractory Questions


How many cubic feet of material is there in the 55 pound and 20 pound bags of castable refractory you sell?

The amount can be found by dividing the amout of material in pounds by the density of the material in pounds per cubic feet. This will give you the amount of material in a bag in units of cubic feet. To find the amount in cubic inches, just multiply a factor of 1728 cubic inches/cubic foot.


Kastolite 26 LI
86 lbs/cu-ft
55=bag amount (lbs)
0.6395= bag amount cu-ft
1105=amount cu-in

Kastolite 30 LI
90 lbs/cu-ft
55=bag amount(lbs)
0.6111=bag amount cu-ft
1056=amount cu-in

Mizzou
141 lbs/cu-ft
55=bag amount(lbs)
0.3901=bag amount cu-ft
674=amount cu-in



Mizzou Questions

Below I've added the manufacturers instructions for Mizzou. They are quite involved for the dryout cycle. In practice, for applications in homemade forges, where you are pouring a shell of a limited thickness (typically 2" - 4"), most people just let it air dry for a from a few days to a week at room temperature and then bring the forge up to temp very slowly by intermittently running the burner for longer and longer periods of time until you bring the forge up to full temperature...you want to do this as slowly as possible. If you are just pouring a hard floor in your forge over top of Inswool, you can be a bit more flexible in your dry times. The key is to let the Mizzou dry slowly.

Mixing & Using Instructions
MIZZOU CASTABLE

--------- GENERAL INSTRUCTIONS --------
Material should be stored in a dry place. Porous back-up materials or wood forms should be waterproofed. Absorption of water can result in reduced flow for the product. Forms must be stout and water tight. This product is designed to be mixed with water and then poured/handcast into place. For best results, water should be maintained at 50-70F.

--------- MIXING REQUIREMENTS ---------
Approximate Water For Installation: 55 lbs. to 5 pints of water.

Mix for at least three minutes. For best results, wet mix temperature should be maintained at 60-75F. Minor adjustments to the amount of water are permissible to achieve desired flow. Do not exceed 11.0% water under any circumstances.

--------- INSTALLATION ---------
Place material promptly. Do not trowel to slick finish. At temperatures above 60F, air cure, keeping surfaces damp and/or covered, for 16-24 hours typically or until a hard set has developed. Lower temperatures will increase the time before a hard set develops. The best results are achieved at curing temperatures of 90-110F. Keep material from freezing during air cure and preferably until a dryout can be initiated. Freezing of this product prior to water removal can cause structural damage.



Mizzou Castable Refractory:

This is a 3000 degree F, High Alumina Castable Refractory for making forges. You can cast the entire refractory liner for a forge or just the floor using this material! This material has a very high resistance to flux, if you're doing a lot of forge welding and have a dedicated forge for forge welding in, this is a great material to use! The only trade-off is that it isn't as good of an insulator as Inswool, but as with all things in life there are trade-offs, and you should consider the benefits of the durability of this material.

- 3000 degree temperature rating
- Highly flux resistant
- Density = 141 lb/ft^3
- Mix with water at a ratio of 5.2# or 0.6 gallons of water per 55#

- This material has a thermal conductivity of 7.4 btu-in/hr-F-ft^2 at 2000 degrees F

 

COLOR TEMPERATURE CHART

This came from the Navy Foundry Manual:

 

This is some info I found concerning a Morgan furnace used to melt iron:

MORGAN FURNACE DATA: IRON

A Morgan furnace has a range of iron melt capacities of 44/110/176/297 pounds (20/50/80/135 kg),
with first melt times of 50/ 60/ 80/ 90 minutes,
and repeat melt times of 45/55/65/75 minutes,
and oil usage for the repeat melt of 3.7/5.5/6.6/11 gallons (14, 21, 25, 42 liters)
(The fuel used for the first melt will be slightly higher than the repeat fuel usage).

The Morgan will melt iron in the four ranges above using 4.9/6.0/6.09/8.8 gal/hr.
I am not sure why the gallons per hour rate is about the same for the 110 and 176 pound melts, but the curve does not seem to be linear.

The Morgan furnace would use 0.084/0.05/0.0346/0.037 gallons of oil per pound of iron.

 

Mifco and Morgan Furnace Data:

 

Got it, thanks.

I decided to post my stash of "foundry data" that I have collected over the past few years, in case anyone does not already have this info.

 

Great idea.

 

Here is some fuel usage and time data I have learned from ironsides and scavenger (these refer to iron melts).

I don't have exact fuel/time data from porositymaster, but his fuel usage and time are reported to be better than anyone else I have seen, ie: he uses less fuel and melts quicker than any other reported time/fuel usage using the Ursutz burner, but also reports damaging clay graphite crucibles at these fuel usage/time values. I have not seen porositymaster using a crucible larger than a #10.
Scavenger I think uses a #70 crucible.

Ironsides (please correct me if I am misquoting this information):

Waste oil furnace - inside dia. 350 mm – height 391 mm (13.8" dia., 15.4" height, inside dimensions)

A20 ? 26 kg melted – cold start 1 hr 40 min – 14 kg waste oil (waste oil 80% 20% diesel)
(57.3 lbs of iron, 30.9 lbs waste oil [diesel is about 7.5 lbs/gal], about 4.12 gal or 15.6 liters of fuel, 0.0719 gal/lb of iron, or 0.60 liters/kg of iron)
4.12 gallons burned in 100 minutes is 2.472 gal/hr, or 9.35 liters/hr.

A12 melt – 14 kg melted - cold start 50 min – 8 kg waste oil (waste oil 80% 20% diesel)
(30.9 lbs of iron, 17.6 lbs waste oil, about 2.35 gal or 8.9 liters, 0.07605 gal/lb of iron, or 0.6357 liters/kg or iron)
2.35 gallons burned in 50 minutes is 2.82 gal/hr, or 10.67 liters/hr.


Scavenger

80 pounds for 6 gallons of oil

A maximum of 8 gallons of oil and as little as 4 gallons of oil to melt an A-40 full of iron.
Humidity, oil quality, and air temp all contributing factors.
A lower-mass furnace will melt iron faster than a higher-mass furnace.

Fastest time: cold start, 60 minutes, 3 gallons of oil
Fastest time: hot start, 40 minutes, 2.5 gallons of oil
Conditions: warm, low humidity, high oil quality.`

Slowest time: 2.5 hours cold start, 8 gallons of oil
Conditions: raining and cold; 100% humidity, poor oil quality.

Average time: 1.5 hours cold start, 1.0 hour hot start.
Average melt with a heavy-mass furnace: 6 gallons cold start, 4 gallons hot start.
Average melt with lower-mass furnace: 4.5 gallons cold start, 3.5 hot start, average time: 1.5 hours cold start, 1.0 hour hot start.

 

So it would seem from the above data that from a cold start, a reasonable fuel flow rate may be 2.5-3.0 gal/hr (for iron melts), with perhaps a slightly higher flow rate for larger melts.

Typical reasonable iron melt times would seem to be in the 1.0-1.7 hour range for typical crucible sizes one may seen (ie: #10 to a #30).
Edit: A typical iron melt using a #10 crucible and perhaps 25 lbs of iron is (1) hour, as tested and verified using this new furnace with a siphon nozzle oil burner running at 3 gal/hr.

The capacity (I think brimful) for aluminum melts is about equal to the crucible number, ie: a #10 crucible will hold about 10 lbs of aluminum.
The capacity for iron is a multiplier of about 2.7, assuming aluminum capacity is equal to 1.0.
The capacity for brass/bronze is a multiplier of about 3.0, assuming aluminum capacity is equal to 1.0.

So a #10 crucible (A-shape is what seems to be typically available; if you can find a bilge shape they have more capacity for a give size), its iron capacity is about 27 lbs.

I hand-poured a #30 with iron, but it was not full, and it was not fun either.
My right hand on the pouring shank was very close to the crucible (no heat shield), and my foundry glove was smoking before the pour was complete. Luckily I was wearing a good glove.
Now days I use a heat shield on the pouring shank, or for very heavy melts I use a pouring cart.

 

I am going to try an iron melt today/tonight.

It is heck trying to find everything after so many months (how many has it been, I have no idea).

The scrap iron will be an old motor housing.
The iron seems to break up easily enough and clean using a heavy hammer.

Fuel will be diesel.
#10 crucible.

I have (4) thermocouples installed at varying heights along the outside of the hot face shell.
Not sure if the thermocouples will survive or get fried, but they were cheap enough.

Toro multi-speed leaf blower running on lowest setting for combustion air.

Not sure what compressed air pressure I will use.
I have been using 50 psi, but I may reduce that to about 25 psi and see how that does.

Now I need to find a pattern of some sort and make a mold, and then I will probably be ready to light the furnace.

I have the camera and so will attempt a video.

 

I pulled off an iron pour tonight.

An iron pour is not something you should rush into after not pouring anything for many months (I am going to check my dates to see how long its been), but rush into it is of course what I did.

Finding all the stuff was a challenged.
Which equipment was most difficult to find? Ironically it was the stuff I had put away in its correct storage location (who the heck would think it would be where it is suppose to be?).
Chalk it up to old age or stupidity (your choice) (or both).

My new water-based green sand was too dry to make a flywheel mold, so I had to relent and make two open-faced ingot molds in the sand.
No time to mull.

I had no idea what flow rate the siphon nozzle burner was set to; I think none; I seemed to have used it last with just a needle valve and no ball valve.

The Toro leaf blower turned out to be way too much air. What the heck; the same setting worked fine for porositymaster.
Its the old adage, what works for thee generally does not work for me.
I had to choke the intake down by perhaps 60% or more.

I got the burner going, cranked up the fuel flow; not sure exactly what the flow was, but just matched it to the combustion air flow so that some flames came out the top.

I did get the thermocouples installed, but that turned out to be a non-starter, since the entire refractory shell turned red hot.
I think the thermocouples were up in the 1700 F, or maybe up above 2,000 F towards the end. I will get some accurate data when I get things cleaned up.

Note to self: Don't attempt iron pours when the outside air temperature is 90 (+) degrees and 80% humidity.
With all the leathers on, I started to experience heat exhaustion towards the end.
I am cooling off indoors at the moment.
Iron melting in the summer down south is definitely not for the faint of heart.

The fuel connection was leaking a little bit, but not too bad, so I forged ahead with the melt (damn the torpedoes as they say).

The camera will only take a video for so long and then it turns off, so I had to turn it back on every so often.
And as usual, everything seems to go wrong at the worst possible time, and the video card filled up right before the pour (wailing and gnashing of teeth, but that is life).

I learned a lot though, and the bottom line is the melt got plenty hot.
I will summarize a bit more once the heat stroke effect wears off a little more.