Donate to goodwill if not cracked or damaged severely. Take it to the local dump if damaged. They have an area for metal recycling. Just throwing it in the trash will make it end up in a landfill.
Vinegar might help with removing surface rust spots if you have a cast iron that's been neglected but it's not a good idea for regular cleaning. If it is well seasoned you might dissolve the non stick layer with the acidity of the vinegar.
Cast iron famously seasons itself with cooking because the oils bake onto the pan. But over-enthusiastic scrubbing, acidic foods, or excessive heat can break down that seasoning. It's a good idea to reseason your skillet a couple of times a year or any time you notice the surface of your pan drying up or rusting.
Start by scoring the cast iron with an angle grinder. This will allow you to control the pieces that break off. Strike the apron of the tub with a sledgehammer and then the sides. Finally, work into the tub deck and continue breaking it down into pieces until it's small enough to be discarded by hand.
If cast iron is left in the sink to soak, put in the dishwasher, or allowed to air dry, it will rust. It can also happen when you store your cookware in moisture-prone environments, such as a cabinet near a dishwasher, an open cabinet in a humid location, or stored outside.
While cutting cast iron with a hacksaw is possible, it may not be the most efficient method, especially for larger pipes or thicker sections.
Iron reacts with simple substances: oxygen, halogens (bromine, iodine, fluorine and chlorine), phosphorus and sulfur. When iron is burnt, metal oxides form.
Cast Iron: 1204°C (2200°F)
Cast iron is very durable. It is an extremely hard metal that offers excellent compressive strength, impressive vibration and damping capacity, and wear resistance. However, it has a very low tensile strength. It is not ductile or malleable, and it can develop cracks and become damaged.
Contrary to popular belief, you can use a small amount of soap to clean cast iron cookware! Large amounts of soap can strip the seasoning off your pan, but you can easily re-season your pan as needed. Can I use steel wool or a metal scrubber to clean my cast iron pan? No!
White vinegar combined with water is an effective solution for removing mineral deposits and buildup from the steam iron's soleplate and vents. Using a small bowl allows you to mix the white vinegar and water in the correct proportions before applying it to the iron.
Try hydrogen peroxide.
Hydrogen peroxide is a mild bleach that lightens stains. Once you've removed any burned food, pour enough hydrogen peroxide into the cookware to cover the bottom at least ½-inch deep.
The best chance of ensuring your cookware doesn't end up in the trash is to head to a local scrap yard. "Metal dealers are often receptive to dropoffs, and if you can cut out the recycling center, they'll accept the pieces they can actually use from you," Hoover says.
The vinegar solution will dissolve the rust, but once that's gone, it can penetrate further and start eating away at the original cast surface of the pan, the ultimate death sentence for your skillet. If that happens, retire it to a piece of farmhouse-chic kitchen decor.
It's important that you use a coarse grained salt—this will provide the traction you need to remove food particles. Using a clean kitchen rag or a folded paper towel, gently move the salt around your pan, scouring the surface.
Cupola furnace. A cupola or cupola furnace is a melting device used in foundries that can be used to melt cast iron, Ni-resist iron and some bronzes. The cupola can be made almost any practical size.
Sulfuric acid was the most efficient in producing labile iron under dark condition, whereas hydrochloric acid induced the most dissolution of the total and ferrous iron in the presence of light.
A ferric reductase enzyme on the enterocytes' brush border, duodenal cytochrome B (Dcytb), reduces ferric Fe3+ to Fe2+.
Potassium permanganate solution oxidizes ferrous iron in water to ferric iron, generating oxygen in the process, which also accelerates iron oxidation.
So my favorite tool for that nasty job is a grinder equipped with a diamond blade. In tight spaces where my grinder won't go, I've always used a reciprocating saw and metal-cutting or carbide-grit blade.
Yes, you can cut iron pipe with a SawzAll. It will take you a while, but you can do it. I would suggest that if you are working on 4″ Drain lines to go to a Tool Rental Center and rent a Cast Iron Pipe Cutter.
Diamond Grit Cast Iron Cutting Reciprocating Saw Blade. A reinforced blade backing allows for straight and accurate cuts. Perma-SHIELD coating prevents gumming, heat and corrosion. This blade is perfect for cast iron cutting, and fiber cement, masonry and fiberglass applications.