History Mystery #118: Cast Iron Object From 1859

Posted by: Don Grove April 4, 2023 1 Comment2,022 Views

Submitted by Karen Morris, Coarsegold Historical Society Chairperson

COARSEGOLD — This object belongs to one of the members of the Coarsegold Historical Society. It is made of cast iron and has three separate pieces. There is a patent date April 17, 1849. It was made in 1859. We are looking for any information to pass along to them.

The Coarsegold Historic Museum is open on Mondays only until April.

Do you know anything about this object? Please let us know!

Coarsegold Historic Museum31899 Highway 41Coarsegold, CA 93614559-642-4448

Cast iron is a strong and durable metal that is used in a wide range of industrial and commercial applications, from piping and machinery to cookware and decorative ornaments. It is made by melting iron and mixing it with various additives to create a strong, yet malleable material. Let’s take a look at the process of making cast iron, from mining the raw materials to producing the final product.

The first step in making cast iron is to gather the raw materials. Iron ore, coke, and limestone are the three main components required for the production of cast iron. Iron ore is mined from the ground and usually contains impurities, such as sulfur and phosphorus, that need to be removed before the iron can be used. Coke is made by heating coal in the absence of oxygen to remove impurities and create a solid, carbon-rich fuel. Limestone is added to the mix as a fluxing agent, which helps to remove impurities and improve the quality of the iron.

Image by Ludomił Sawicki.

Once the raw materials are gathered, they are combined in a blast furnace. The blast furnace is a large, cylindrical structure that is lined with refractory bricks to withstand the high temperatures of the furnace. The furnace is filled with alternating layers of iron ore, coke, and limestone, and a series of high-pressure air blasts are introduced at the bottom of the furnace. These air blasts heat the furnace to over 2,000 degrees Fahrenheit, causing the coke to ignite and reduce the iron ore to molten iron.

As the iron ore is reduced, it forms a layer of liquid slag on top of the molten iron. The slag is a byproduct of the reduction process and is made up of impurities that have been removed from the iron. The slag is removed from the furnace through a tap hole at the base of the furnace, while the molten iron is drained into a ladle and transported to a casting facility.

Image by Ludomił Sawicki.

At the casting facility, the molten iron is poured into molds to create cast iron products. The molds are made of sand or a similar material that is coated with a refractory material to withstand the high temperatures of the molten iron. Once the molten iron is poured into the mold, it is allowed to cool and solidify, forming a solid cast iron product.

The quality of the cast iron depends on the composition of the raw materials and the casting process. Different additives can be added to the molten iron to improve its strength, hardness, and other properties. For example, silicon can be added to increase the strength and wear resistance of the cast iron, while nickel can be added to improve its ductility and toughness.

Image by Blake Carpenter.

In addition to additives, the casting process itself can also affect the quality of the cast iron. The cooling rate of the molten iron can be controlled to create different types of cast iron, such as gray iron, ductile iron, and malleable iron. Gray iron is the most common type of cast iron and is characterized by its gray color and high carbon content. Ductile iron is more flexible and durable than gray iron and is used in a variety of industrial applications. Malleable iron is a type of cast iron that can be bent and shaped after casting, making it ideal for decorative and ornamental purposes.

The process of making cast iron is a complex and fascinating one that involves a variety of raw materials and additives. From mining the raw materials to casting the final product, each step in the process plays a critical role in determining the quality and properties of the cast iron. As a versatile and durable material, cast iron has played a vital role in human history and will continue to be an important part of our industrial and commercial infrastructure for years to come.

Antique Amp Meters Blake Carpenter blast furnaces carbon cast iron Coarsegold Coarsegold Historic Museum Coarsegold Historical Society coke cookware Don Grove ductile iron gray iron History Mystery iron ore Karen Morris limestone Lodge Cookware Ludomił Sawicki malleable iron molten iron nickel phosphorus refractory bricks silicon slag sulfur