Coke (fuel)

Coke is a hard, grey fuel.

It is made by heating coal. This happens in a special oven. There is no air in the oven. The heat drives out water and gas. This leaves behind the coke.

It is very porous. This means it has tiny holes. Coke is used to make iron. It is also used in stoves. It can burn with very little smoke.

It is a very useful tool for making things.

Coke is a hard, grey fuel. It is made from coal.

People make it through a way called coking. This means heating coal in a special oven. There is no air inside the oven. The heat is very high. It can reach 2,000 degrees Celsius. This heat drives out water and gas. It also drives out coal tar. What is left behind is coke. It is a hard, glassy solid.

Coke is very porous. This means it has many tiny holes. These holes help it work well.

Coke is very useful in industry. Its main job is smelting. Smelting is a way to make pure metal from ore. Coke helps turn iron ore into iron. It is also used as fuel for blacksmiths. People use it in stoves and forges.

This is because coke burns with very little smoke. It is much cleaner than regular coal. Some coke is also made from petroleum. This is called petroleum coke. It can be used to make parts for batteries.

Coke is a hard, grey fuel that looks almost like glass. It is very porous, which means it is full of tiny holes.

This material is much more than just a way to start a fire. It is a vital tool for making metal. Most importantly, it helps in the smelting of iron ore. Smelting is the way we turn raw iron ore into pure iron. Because it burns so cleanly, it is also a great fuel for stoves and forges.

Making coke is a special way of working called coking. It starts by heating coal or petroleum in a place with no air.

Inside a large oven, the heat can reach 2,000 degrees Celsius. This extreme heat causes the organic parts of the coal to break down. Water, coal gas, and coal tar are driven off as vapors. What stays behind is the non-volatile residue. This residue is the hard, carbon-rich coke we use.

People have used different ways to make coke for a long time. In the first half of the 1800s, people used the "hearth" process. This involved making a large heap of coal and covering it with coke dust.

Two big changes made this old way less common. First, a man named Neilson introduced a hot air blast in Scotland in 1828. Second, people began using the beehive coke oven. These ovens are shaped like domes and are about 4 meters wide.

Not all coal is the same when it comes to making coke. To get good results, workers must blend different types of bituminous coal. They look for specific levels of moisture, ash, and sulphur.

For example, a good blend should have 26% to 29% volatile matter. The finished coke is even graded by how much ash it has left. Steel Grade I has no more than 15% ash. Other grades, like Washery Grade IV, can have up to 35% ash.

Coke connects to many things we use in our modern world. It can be used to create syngas, which is a mix of hydrogen and carbon monoxide.

This gas can be used for many different industrial jobs. Some coke is even made from petroleum in refineries. This petroleum coke can help make parts for dry cells and electrodes. Even the leftover waste from the process can be useful. Some people use the leftover slag to make bricks, cement, or even fertilizer.

Coke is a hard, grey, and porous fuel with a very high carbon content.

It is a vital industrial product used primarily for the smelting of iron ore. Smelting is the chemical process used to extract pure metal from raw ore. Because coke burns with very little smoke, it is also used in stoves and forges. While most people think of coke as a coal product, it can also be made from petroleum. This version is known as petroleum coke, or pet coke. Some coke may even form naturally through geologic processes deep within the Earth.

The production of coke from coal is a process called coking. It involves heating coal in an airless kiln, often called a coke furnace or coking oven.

During this process, temperatures typically reach between 1,000 and 1,100 degrees Celsius, though they can climb as high as 2,000 degrees Celsius. This intense heat causes the organic substances in the coal to decompose or vaporize. Water, coal gas, and coal tar are driven off as volatile products. The coke that remains is the non-volatile residue. It is a hard, somewhat glassy solid made of cemented-together carbon and mineral residue.

To make high-quality coke, workers must carefully select and blend specific types of bituminous coal. They use coal assay techniques to check for moisture, ash, sulphur, and volatile content. A successful blend usually contains between 26% and 29% volatile matter. This balance ensures the coke is strong enough for industrial use without causing too much pressure in the ovens. The resulting coke is graded based on its ash percentage-by-weight after it burns. For example, Steel Grade I contains no more than 15% ash. In contrast, Washery Grade IV can contain up to 35% ash.

Historically, the way coke was made has changed significantly. In the early 19th century, people used the "hearth" process. This involved making a large heap of lump coal and covering it with coke dust.

This method was very slow and lengthy. Two major inventions changed this. In 1828, a man named Neilson introduced the hot blast in Scotland. This allowed for hot air to be used in smelting furnaces instead of cold air. Later, the beehive coke oven became a common tool for production.

A beehive oven is a firebrick chamber shaped like a dome.

These ovens are usually about 4 meters wide and 2.5 meters high. Coal is loaded through a hole in the roof to create a layer 60 to 90 centimeters deep. The process of carbonization starts at the top and moves downward. It takes about two to three days to complete. In older beehive ovens, the volatile gases were simply burned to provide heat, meaning no by-products were recovered. In modern "by-product" ovens, these gases are collected and purified for use in other industries.

Coke is incredibly useful in many different chemical and industrial ways. In a blast furnace, coke acts as both a fuel and a reducing agent. When coke burns, it produces carbon monoxide. This gas reacts with iron oxide, specifically hematite, to produce pure iron.

Coke can also be used to create synthesis gas, or syngas, which is a mixture of carbon monoxide and hydrogen. By passing steam over red-hot coke, engineers can produce water gas. By passing air over red-hot coke, they can produce producer gas. These gases are essential for various chemical processes and fuel needs.

Beyond heavy industry, coke has many specific applications. Petroleum coke is used to manufacture electrodes for welding and dry cells. In foundries, finely ground coal called "sea coal" is added to sand molds. When the metal is molten, the coal burns slowly to release gases. These gases prevent the liquid metal from soaking into the pores of the sand. Even the waste from the process has uses. The slag, which is the accumulation of impurities, can be used to make bricks, cement, or fertilizer.