Saturday, February 1, 2014

Backyard Smelter Revisited




Aluminum Ingots Melting In Backyard Smelter - 2007

A while back on Facebook, some people shared a link which showed the results of pouring molten aluminum down an ant hill.  The result once the aluminum cooled down, the ant hill excavated, and the resultant mass of metal cleaned up was a very intricate and modern art type sculpture.  The molten aluminum had filled all of the small underground tunnels exposing the complexity and industriousness of the tiny ants.  In response to the link I replied, rather fallaciously, that I would have to give it a try the next time that I was melting aluminum in my back yard.  I had melted lead in the backyard of my parent's home but that was in the days before the EPA and OSHA.  Since my father was a plumber, we had all the equipment required to make cast lead joints in soil pipe (cast iron sewer pipes) or in my case, cast lead sinkers for fishing and lead weights for skin diving.

Although I have neither the intention, need, or equipment to melt aluminum in my backyard, there are people in Thailand who do.  I have written about people here in Thailand who weave cloth, weave reed mats, make fishing nets, weave baskets in their yards.  I have written about the experience of watching people in Laos making knives, moonshine whiskey, bird snares, and rat snares in their yards.  Well this blog is about having your own aluminum foundry in your yard.

Samut Sakhon Home With Casting Cores - 2007
In March 2007, Duang and I visited the Samut Sakhon area.  One of our visits was to the home of Duang's granddaughter.  It was nice to see the child and there was an added bonus - the operating family run aluminum smelter in their backyard.

Samut Sakhon is a province south west of Bangkok.  The area is dotted with many industrial sites ranging from food to chemicals.  There are also many orchards that produce fruits as well as farms that cultivate shrimp.  The land is low and flat.  Just as Thai food is a mixture of flavors, colors, and textures, Samut Sakhon is a mixture, a melange,  of heavy industry and agriculture with the borders of each often touching.

Duang's granddaughter lives with her other grandparents in an elevated wood house down a very narrow rutted dirt road in an area that is crisscrossed with many canals.  They have the family run aluminum smelter in their yard.  The smelter produces various items under contract to many different clients.  It is a small smelter that uses sand casting method to produce various items such a roof drains, heating plates, and equipment parts.

Preparing to Remove Cast Plate From the Mold
On our trip back in 2007, I was excited to see the foundry operation.  It brought back some memories of the summer of 1970, when I worked at ITT Grinnell in Cranston, Rhode Island.  During part of that summer while attending university I worked in the labor pool that filled in for absent workers who were involved in producing cast iron fittings mostly for sprinkler fittings.

In Samut Sakhon, just as in Rhode Island, the casting process involved starting off with a pattern - a metal three dimensional representation of one half of the object to be made.  A wood frame is placed on top of the pattern, and filled with sand or special sand mixture.  The sand is pressed and compacted in the frame which is on top of the pattern.  When the frame/compressed sand assembly is lifted off of the pattern, the pattern has created an impression in the sand for one-half of the object to be made.  The process is repeated for the send half of the object to be made.  The two frames are then stacked and attached so that they create the mold,complete volume, of the object between them.  If the object is to have hollow sections, special inserts, called cores, are placed in the bottom half frame before assembly so that the molten metal will flow around them rather than forming a solid section.  Often the pattern will also contain channels and features to ensure that the poured liquid metal properly flows into and completely fill every aspect of the mold. A pour hole and vent hole at the other end of the mold allows the molten metal to completely fill the mold and provides visual indication the the mold if filled.

For the backyard smelter in Samut Sakhon this molding process occurred in the front section of the ramshackle structure that constituted the foundry.  The structure was single story built out of wood, timbers, and corrugated metal and not necessarily weatherproof - there were many gaps, holes, and voids in the walls.  There were no doors or windows in the structure.  There were door and window openings which provided access and some natural cross ventilation. All surfaces of the structure were covered with a thick layer of fine black dust from the casting sand and smoke of the furnace.  The roof above the furnace was much better maintained for obvious reason - water falling into molten aluminum would definitely ruin several people's day.

Loading Aluminum Ingots Into Furnace
Smelting of the aluminum was conducted in a small open topped furnace about the size of a 55 gallon drum - a 55 gallon drum that had been heavily lined with refractory.  Off to the side of the drum connected by a pipe was an electric fan which created the forced draft for the burner beneath the furnace.  There were other drums containing what appeared to be recycled motor oil.  The contents of the barrels were pressurized by a small pump and fed into the burner beneath the open refractory lined drum.  Do to the lack of pollution controls and adequate burner management, heavy dense black smoke billowed from the short chimney that stuck up above the roof directly above the furnace.

The Smelter's Granddaughter
Whereas the front section of the building was filled with three workers, two or three soi dogs (street dogs), an concessional wandering chicken, children playing, and a visiting falang (foreigner), the back section where the furnace was located and partially separated from the front by a half wall was occupied only by the owner of the business.  The combination of heat from the melting and molten aluminum, retching acrid smoke, and obvious danger kept others out.  Once the aluminum was melted and the furnace was throttled back to keep the metal molten, workers from the front entered the area routinely to fill their ladles to pour into the molds located in the front.

Pouring Molten Aluminum Into Mold

 Wearing rubber flip flops, polyester shorts and cotton tee shirts and no eye protection, gloves or any expected safety equipment that you would expect for handling 1200F molten metal, the workers filled the many assembled molds for the day's scheduled pour.  Their clothing and exposed skin quickly becoming caked with sweat, casting dust, and smoke residue - all reminders of my days at ITT Grinnell ( I was fond at the time of saying often "Who put the "grin" in Grinnell?) for, unlike the smelter in Samut Sakhon, it was not a happy place or was there much smiling let alone laughing.

Completed Castings Cooling
The poured molds were left strewn about the cast sand layered concrete floor of the front of the foundry to cool sufficiently before the the frames were removed to expose blocks of hardened casting sand, baked cores and aluminum.  Rods and hammers were used to manually break away the hardened casting sand to expose the aluminum castings.  This work added to the dust already in the air from previous activities.  Metal rods with a hook shape on the end were employed to remove the castings from the casting sand debris on the floor and to relocate the still very hot castings to piles in another area for further cooling.

After cooling completely the workers trimmed excess metal to be recycled in the next charge of the furnace. Hand files and electric grinders were then used to clean up the castings for delivery to the customers.

Well that was then and this is now.  Buddhists believe that every thing changes and nothing exists without change.  We returned to Smut Sakhon after seven years and there had been some changes.  The grandfather, the owner of the business, had died.   His wife was now running the business but not doing the physical labor as her husband had.  The granddaughter who was 4 years old at the time is now a lovely 11 year old doing very well in school.  Most of the workers had been replaced.  The narrow dirt road is even more rutted now and vegetation has encroached upon it making it even more narrow.

As many changes as there were, there were some things that had not changed or rather - had not changed yet.  One of the workers that I had photographed in 2007 was still working there.  Dogs and chickens still wandered about the work area.  The building was no worse for wear but no better either.  The round concrete table and bench seats were still located at the front of the building.  Various materials and items associated with the casting business still were strewn about the property.

We arrived in the early evening after the casting had been completed.  I went in the back to the idle furnace and observed nothing new or even changed.  My stay in that portion of the facility did not last long due to the extreme heat radiating from the furnace and molten aluminum that it still contained.

Removing A Core From Casting
In the front of the facility, men, as the day was coming to an end, were occupied freeing the castings from the hardened casting sand and removing the cores from the castings.

Cleaning Up Aluminum Castings

Chipping Away At A Core

Getting To The Core of the Casting, Chipping Away
It always interesting for me to see how people make their living here as well as the other countries that I have been to.  I especially like to witness people exhibiting their independence and self-sufficiency.  It always astound me how people can get by with so much less than I am accustomed to or have been exposed to.  A principle that drives their efforts is "Fit for purpose"  However I am also very grateful to not have a smelter in my backyard or even in my neighborhood.

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