METAL MANUFACTURING AND FURNACES
Manufacturing is broadly described as the process in which materials are transformed into valuable substances. The process involves one or more processing and/or assembly procedure. The manufacturing process adds value to the material after a change in its properties.
The metal manufacturing sector is a prominent segment of the manufacturing industry that smelts and/or extracts non-ferrous and ferrous metals from raw ores, pigs, or scraps. This prominent sector uses electro-metallurgical and other metallurgical techniques. Be it ferrous or non-ferrous, all metals undergo extensive procedures before the outcome is obtained.
This initial procedure of the entire process is smelting. In the first procedure, metal is extracted from its ore. This is done by heating the ore beyond its melting point. The base metal is obtained from the ore using heat and a reducing agent. During the entire process of smelting, the ore is decomposed and all other elements are eliminated, as a result, the metal is extracted in its purest form. In this form of extractive metallurgy that separates the valuable metal from its ore, the temperature is set above the melting point of the metal.
Smelting involves two crucial steps, i.e. roasting and reduction. Roasting is carried out inside an industrial furnace. The combustion of the raw ore takes place inside the furnace where heat is provided directly for the industrial process. A furnace is the most reliable type of industrial manufacturing equipment that is used for production and processing. The products are heated either by direct or indirect contact through the combustion of gases and fuels.
What is Industrial Furnace?
Various industrial furnaces are used for different activities within an industrial unit. An industrial furnace is a device that serves as a heat chamber. A well-designed furnace allows maximum heat transfer to the material within a definite time. The heat within the chamber is generated by the furnace after the fuel mixes with air or oxygen. Heat is also generated from electrical energy. There are international standards and codes for designing furnaces.
How do the furnaces work?
The functions of furnaces vary according to the designs based on the desired outcomes. Though wood and coal were used as fuel in traditional furnaces, those have been replaced by modern furnaces which use electricity for heat. However, traditional furnaces remain the most used. Unlike traditional furnaces, modern-day furnaces don’t cause so much pollution, are not labor intensive, and also do not need all-time vigilance to maintain heat for operation. Modern-day electric furnaces use resistance or induction heating. These electric furnaces are environmental-friendly as they don’t release gases. But, modern-day furnaces are quite expensive.
The fuel is burnt after it is supplied to the burner in the furnace. The burners have oxidizers that change chemical energy into thermal energy. The burners determine the type of fuel used in the furnace. Next, the burners mix the fuel and air to ignite them. The burners transfer the heat to tubes located in a chamber through radiation. In this process, the fluid present in the tubes gets heated. The hot air or flue gases are emitted through the stack or chimney. The gas emissions are strictly controlled to avoid releasing harmful gases.
Types of furnaces used in metal manufacturing
There are several types of furnaces that are used widely for metal manufacturing. Furnace construction includes typical components like heat exchangers, air blowers, burners, fuel controllers, ignition devices, control circuits, and thermostats. Further, the designs of the furnace vary with the need of the application. Furnace types get classified mainly by the type of fuel used and the process of combustion initiated. For metal manufacturing, different types of furnaces are used throughout the process which uses various technologies.
Blast furnace
A blast furnace is used for melting the raw iron ore into pig iron. Mostly, these types of furnaces are cylindrical and are used for smelting. Further, the blast furnaces are classified into two categories, i.e. cold blast and hot blast. In the cold blast process, the air blown into the furnace is not preheated whereas, in the hot blast, the air blown into the furnace is preheated. Unlike the cold blast type, the hot blast technique reduces fuel consumption. Moreover, the hot blast process allows for higher furnace temperature, which ultimately increases the furnace capacity.
Puddling furnace
A puddling furnace is used for creating wrought iron or steel from pig iron. These types of furnaces are designed to pull the hot air over the pig iron while preventing any contact with the fuel. These are also known as open-hearth furnaces or reverberatory furnaces.
Basic oxygen steelmaking
Basic oxygen steelmaking is a method of steelmaking in which oxygen is blown through molten pig iron to lower the carbon content and convert it into low-carbon steel. As chemical bases like dolomite or fluxes of burnt lime are used for removing impurities, the process is called basic.
Electric arc furnace
Electric arc furnaces heat materials through an electric arc. The charged materials are directly exposed to the electric arc and the power from the furnace passes through the material. The temperature of an industrial arc furnace can reach up to 1,800 degree Celsius (3,300 degrees Fahrenheit).
Induction furnace
In an induction furnace, heat is applied by induction heating of the metal. Induction furnaces are used to melt steel and iron as well as precious metals with a capacity range from less than one kilogram to one hundred tons. These furnaces are energy-efficient and clean, and ensure a well-controlled melting process, unlike other metal melting furnaces.
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