ESTA OMEGA

Introduction

Types of furnaces

The first step in casting is to melt the desired metal or alloy. This operation is done in devices called furnaces.

The types of furnaces are as follows

Shrub Furnaces:

In these furnaces, the melting operation is performed inside a chamber called a plant

These furnaces are usually used as fixed or rotating

Coupling furnaces:

These kilns, whose generation is almost extinct in Iran, have a cylindrical shape and can be used to melt cast iron or regenerate iron ore.

Flame furnaces:

We will explain this in detail later

Electric ovens:

Divide copper into 3 categories

a. Induction

That the metal melts through electrical induction

B. Electric arc

In these furnaces, the energy required for melting is obtained by creating an electric arc between the charge and the electrodes or the electrodes together.

J. Resistance furnaces

These furnaces are usually used for heat treatment or as a melting retainer

Flame furnaces

Classification of furnaces based on how the melt comes into contact with fossil fuels and flames:

1. Furnaces that have nothing to do with fuel or combustion products

Like plant ovens

2. Furnaces that are in contact with the fuel combustion product

Like flame furnaces

3. Furnaces that are in contact with the shovel itself

Such as coupling furnace and blast furnace

Types of furnaces related to the combustion product

1. Siemens Martin furnaces

These furnaces are commonly used for ferrous alloys and steels

2. Thomas-Bessmer Furnaces

These furnaces are also commonly used for ferrous alloys and steels

3. Barrel furnaces

Widely used in Iran for smelting cast iron and aluminum

4. River furnaces

These furnaces, also known as chamber furnaces, are used to melt aluminum and its alloys.

The main discussion of this project is about river furnaces

River furnaces

To define these furnaces, it is better to answer the following questions

What is the construction of the furnaces like?

When are river furnaces used in smelting aluminum?

How is the melt heated in these furnaces?

What is the refractory used in these furnaces?

What is the efficiency of the furnaces?

What is the advantage of these furnaces compared to ground furnaces?

What are the disadvantages of this oven?

Refractories used in these furnaces:

These kilns use aluminosilicate bricks

In the part of the plant and a little above it, quarantine bricks with about 95% alumina are used.

Above it are bauxite bricks that contain about 80% alumina

Are used and also used in higher parts of bricks that have a lower percentage of alumina

Impact materials and insulating materials are used behind the refractory materials

They usually use ceramic blankets and calcium silicate slabs

The reason for using aluminum bricks, in addition to being neutral to the molten aluminum, is the high compressive strength of these bricks in the hot state.

River furnace efficiency:

The efficiency of these furnaces is usually about 40%

(Existence of chimney and hot air exit from these furnaces is one of the reasons for reducing efficiency)

Advantages of these furnaces compared to ground furnaces:

1. High melting speed is one of the most important advantages of this furnace compared to plant furnaces

2. In these furnaces, the melting tonnage can reach up to 90 tons

3. The efficiency of these furnaces is higher than ground furnaces

Disadvantages of this oven:

1. Inability to control the atmosphere of the furnace

2. There is some temperature difference between the upper part of the plant and its lower part