Hildstrom Engineering ... interesting induction furnace project. Someday ... an induction heater would be handy to have around. It's a lot less BS for probably 80% of what a guy needs. If you could get one built big enough to melt 100 lbs of bronze, you'd have a really nifty foundry. In a DIY setting I am afraid that would probably tax the available power to the house.
"Hello, PG&E, yes I need a service upgrade. What for? Uh ... well ... I have this really big medical marijuana green house I'm building ... what? ... oh yeah totally for personal use. I've got arthritis real bad ... oh ... prescription? Let me find that and get back to ya .... yeah, thanks ... you too ..."
Maybe 25 lbs ...
Tuesday, November 8, 2011
Approaching dry
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| "Older Slab" |
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| "Newer Slab" |
Started the kiln today. One benefit of being home sick, I guess, is that I can run these whilst I sit on the couch. Another day at 190 F.
Making some progress. You can sorta see the color differences in these two shots. These are both shot with the flash in the shade to minimize color variance from the sun. The older slab is beginning to get and stay white. Well whiter. The mold has either gone away or bleached out or something.
The newer slabs are still, by comparison much darker. Mold is still present. In fact when I turned them this morning there was mold on the shelves. Who knew mold was happy at 190 F? There's something to think about when you are looking at toasting that last piece of bread that may have been around a day too long ... ewww.
You can see where I'm losing the corners. They are either flaking off or I keep hitting them on the sides of the kiln. Not critical. If these make it through firing, I can grout that with the Sairset and some silica sand.
Not real exciting stuff right now, but this is what I get for too much water in the mix.
You'll burn your eye's out kid
Check this out - An old Popular Science Article on making a small arc furnace. I think I've discovered my problem. All this time I've been mucking around in my home laboratory in jeans and a t-shirt. Apparently a jacket and a bow tie are actually the fashionable choice. Who knew?Link to the page where I found it.
Monday, November 7, 2011
Interesting Paper From Purdue
ATLAS FOUNDRY COMPANY, INC.
Marion, Indiana
July 1996
POLLUTION PREVENTION TECHNOLOGY IMPLEMENTATION REPORT
INTRODUCTION
Atlas Foundry Company and the Indiana Pollution Prevention and Safe Materials Institute (IPPI) have worked together for several years on projects involving routine Community-Right-To-Know and hazardous-chemical-use reporting to the EPA. The company was, thereby, aware that IPPI collaborates with companies throughout the state, including other foundries, to reduce hazardous chemical use and/or emissions. Atlas Foundry made plans to convert from a cupola melting furnace to an electric induction furnace process and, knowing of IPPI's pollution prevention and pollutant emissions reduction work, contacted IPPI with an invitation to review this change of process with regard to hazardous chemical emissions, solid waste reduction and economics.
COMPANY BACKGROUND
Atlas Foundry Company, Inc., which manufactures gray iron castings, is a family-owned business, which was founded in 1893 and is located in Marion, Indiana. They produce a wide variety of castings, usually less than fifty (50) pounds in weight. The company employs 131 people and, in the past, produced in excess of 17,000 tons of iron each year, utilizing a 1940's-vintage cupola melting furnace capable of twelve (12) tons per hour, continuous.
MANUFACTURING PROCESS
Atlas' cupola furnace was typically charged and recharged with a combination of pig iron, steel scrap, iron manganese briquettes, coke, and gray iron waste from prior casting (gates, risers, unacceptable cast parts). The molten gray iron, thus produced, was transferred from the cupola via ladle to a forty (40)-ton storage furnace. From the storage furnace, molten gray iron is transported throughout the facility in small ladles and poured into various sand molds. After a casting has been poured, cooled, and separated from its sand mold, gates, runners, and risers are removed and the casting is placed on a conveyor and transported to a shotblasting area to be cleaned. Following cleaning, the casting is inspected and touched up, as required, to remove excesses at parting lines and so forth. Testing of the 'brinell' hardness level, related to the ultimate strength of material of the casting, determines its acceptance or its return for remelt. A significant quantity of gate and riser material (along with a small percentage of imperfect castings) provides a remelt factor of approximately 40% of the total cast material. Viewed from the contrasting perspective, 60% of the gray iron produced is in the form of product, and the balance is recycled as a natural part of the process.
ENVIRONMENTAL ISSUES
The foundry industry has historically been characterized by large quantities of emissions and waste residues. This has been the case for the primary processing/refining of raw ore as well as the secondary production of metals such as gray iron castings. In this secondary metallurgical process, the major air contaminants occur as metallic fumes, smoke, and dust. Significant amounts of landfill waste are also generated as expended sand, sludge, slag, baghouse dust, etc.
Cupola-type furnaces use coke as a fuel. Iron is melted by the burning of coke and flows down the cupola. As melting proceeds, new material is added at the top. Added flux combines with nonmetallic impurities in the iron to form slag, which is lighter than molten iron and separates. Both the molten iron and the slag are removed at the bottom of the cupola. Sand is used as a refractory lining in the cupola and must be dropped at the end of each day's cupola operation. This is not a reusable waste (cupola drop).
Complete conversion of carbon that is present in the coke (producing 100% carbon dioxide [CO2]) in cupola melting is undesirable. Highly efficient fuel burning would result in oxidation of the iron as it is melted and runs down through the cupola stack. Such oxidation is minimized by assuring the presence of carbon monoxide (CO). During the iron's descent, it is in direct contact with the offtake gas, which purposely is oxygen poor (about 11% CO content). This minimizes the oxidation of iron but results in less efficient use of the available energy from the coke and, also, in the release of copious amounts of CO gas emissions to the environment.
The cupola process inherently produces a significant amount of particulate emissions. A high energy scrubber unit had been part of the structure since 1987. Ninety-nine percent (99%) of the particulate generated was directed to this scrubber, of which 95% was removed from the final cupola stack emissions. The resulting scrubber sludge is a landfill waste.
Although the basic pig iron used in the process contains no lead, scrap iron used as a part of the process is generally thought to occasionally contain some small level of this element. When it is present, some portion of it invariably will become a part of the emissions scenario.
Gray iron, by design, contains an EPA-reportable, heavy metal ingredient--Manganese (Mn). In 1995, the gray iron manufacturing operation resulted in a reported release of almost 10,000 pounds of this material to landfills or in air emissions.
P2 PROJECT
Atlas Foundry Company established a project to replace the cupola furnace with two, four-metric-ton, batch-load, electric coreless induction furnaces. This type of furnace produces substantially lesser amounts of environmental pollutants. The electric induction furnaces are cylindrical or cup-shaped, refractory-lined vessels that are surrounded by electrical coils. A 2500 KW, 200-300 Hz, power module energizes the coils, producing a fluctuating electromagnetic field which heats the metal charge. Typically, they are kept closed-- except when charging, skimming, or removing the molten metal, which is accomplished by tilting the unit hydraulically.
These new furnaces are located in close proximity to the 40-ton holding furnace. A cold batch of material is loaded and full power applied. As melting proceeds, additional material is added until full charge is reached. When the complete charge is melted, the furnace is slagged, temperature and chemical composition are checked and adjusted, the furnace is slagged-off, its temperature is raised to 2750 degrees F, and the material is transferred to the holding furnace. A 25,000 cfm dust and fume collection hood system over the furnaces collects and filters out particulate and fume emissions. This type of furnace uses no coke, produces no CO emissions, and, therefore, achieves an immediate and significant pollutant reduction. Although some form of energy conversion must take place elsewhere to produce the electric power required, unlike the cupola, there is no purposeful production of CO rather than CO2 in power generation operations. The CO reduction at Atlas is truly a reduction--not a transfer. There is no cupola drop, at the end of each day, producing air emissions and related landfill waste. There is, however, the need to periodically dispose of spent furnace lining material. Slag production is greatly reduced because the basic charge is much cleaner. There is no cupola scrubber sludge to be disposed of at a landfill although a much lesser amount of dry baghouse dust does require disposal.
Reduction of the above wastes and related particulate emissions have a direct, positive effect in reducing the amount of manganese (Mn) released by the operations.
The incorporation of these furnaces will allow for easier, future expansion of the range of iron alloys produced. Some of these would conceivably contain chromium. On a "what-if" basis, these furnaces would provide the same percentage reduction in emissions of chromium as achieved on manganese when compared to cupola production.
POTENTIAL ENVIRONMENTAL AND COST BENEFITS
First and foremost, a recalculation of 1995 Form R data, using the latest available input for the cupola operation and comparing to the values for an electric induction furnace, yields a 53.2% reduction in releases of manganese, overall. Releases to the air are reduced more than 25% and landfill input is reduced by 59%.
The furnace related operations are only a portion of the total source of landfill wastes and air emissions at Atlas (or any other foundry), but, the other sources (such as shakeout to remove castings from the sand molds) did not change as a result of this project. Only the environmental emissions and wastes associated with this project are covered in the following summary:
Calculations based upon the comparison table reveal:
Furnace related pollutants have been reduced 99.5%.
Furnace related landfill waste has been reduced 92.1%.
A cost comparison made by Atlas Foundry indicates $49.98 - 43.08 = $6.90 per melted ton reduction in related operating costs. At the 1995 annual melt rate of 18,273 tons, the savings produced is $126,084 annually.
Various sources of economic assistance have been available, such as local economic revitalization capital investment tax abatement, a low cost economic incentive loan, and power usage discounts, which help to reduce the payback of approximately $1.25 million outlay to an acceptable level. Flux materials are added that combine with nonmetallic impurities to form slag which, being lighter (less dense) than the molten metal, separates from the metal.
(c) Purdue University Research Foundation, 1996
One more day ...
Started the kiln up at about 09:55. Leaving it set for 190. It had cooled down to 55. The lid is open about 2 inches to allow for air circulation. Last night when I stopped there was no sign of cracking on the oldest slab.
Sunday, November 6, 2011
Slabs have been in the kiln for about 14 - 15 hours yesterday and 11 hours today at 160. The one I cooked last week is still damp. I just ran the temp up to 190 F. It's 16:00 now. I'll shut it down at 21:00. That'll give it five hours with 30 degrees more temp.
190 is the limit. I got cracks at 200 in the first sample.
I haven't been feeling well this weekend, so no progress on anything else. Good race at Texas today. Nice to see Tony Stewart coming back.
190 is the limit. I got cracks at 200 in the first sample.
I haven't been feeling well this weekend, so no progress on anything else. Good race at Texas today. Nice to see Tony Stewart coming back.
Saturday, November 5, 2011
Moon Rocks
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| Moon Rocks! |
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| Next to the lens cap for some scale |
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| Some of the bigger chunks |
I decided to take it to a cone firing at that point. I reset the controller for I think cone 05 or 06. I wanted to at least get the organics burned off.
About an hour later it was at 900. I peeked in again. It had begun to collapsed. Most of the black had gone away. I think at that point I let it go for another few hundred degrees. It was at about 1100 - 1200 that I opened it up again and shut it down. While there was a lot of white, it had fallen apart at this point and there was a glowing red core in the middle of the pile. I could see through a hole in the pile. Looked very volcanic.
So now I am drying the slabs I made. I'm going to see if drying them at 160 degrees F will make a difference.
I think the seeds are a bust. Big holes in the matrix may not leaving enough clay to stabilize the structure during the burn off. This has got to be leading to concentrations of stress and then crack propagation. It was also suggested that the seeds may be expanding during the process and there's a thought that the high oil content may be creating too much hot gas too fast.
Two other things missing in my mix are a larger aggregate and a flux. The chunks from this run can be used as a grog. If the other slabs bite the dust, they can be grog too. The other option is to get some silica sand.
For my next trick, I am going to go to small batches with different mixes. All will be with way less water and some slake time. "Frosty" at iforgeiron.com made a whole bunch of suggestions about how to mix it.
I'm thinking this for trials:
- Clay blend but with sawdust
- Clay blend with flux and seeds
- Clay, flux, and sawdust
- Clay, flux, seeds
- Clay, silica sand, sawdust
- Clay, silica sand, seeds
- Clay, silica sand, flux, sawdust
- Clay, silica sand, flux, seeds
- Clay, grog, sawdust
- Clay, grog, seeds
- Clay, grog, flux, sawdust
- Clay, grog, flux, seeds
I have to research what to use for a flux. Fluxes are elements or compounds that cause other elements or compounds to flow, generally at lower temperatures. Some also drive off impurities. Soldering flux is what most of us are used to.
An example is boron & silica. Pure silica will not melt until something near 3000 degrees F. Throw in a little boron and that drops to the 1300 deg. F range. I don't think boron is a true flux in this case as it sticks around.
I'm going to go 2 - 3 at a time so I learn something as I go and hopefully I can adjust and close on a successful formula faster. So ... time to break out the spreadheet and do some math.
Oh ... I found perlite at Home Depot. So that's going to go in here someplace too. A reportedly successful castable mix is to use refractory mortar mixed with perlite. I have some Sairset mortat. So, I may try a small batch of that with perlite in the first run too.
Meanwhile the slabs are in the kiln at 160 F for a couple more days I s'pect.
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