The chart of direct reduced iron prices in the market and in major companies varies from one to another. Today, one of the most efficient processes for the production of iron ore pellets and the production of sponge iron is a gaseous direct reduction mechanism.
In this method, the regenerator is natural gas. Typically, this gas is considered methane (CH4). (About 85% of natural gas is methane, so methane is considered an approximation of natural gas).
In the direct regeneration mechanism, pellets are transferred from the upper side of the furnace to the deep part. During this time frame, the regeneration gas also diffuses into the furnace at the same time.
As mentioned, they combine hydrogen and carbon monoxide. Of course, these two gases are produced by cracking and decomposition and then transferred to the reformer furnace.
Due to the natural flow of hot liquid (1000°C), the regeneration gas normally moves upwards. During this combination process, as the particles fall, their percentage of oxygen decreases. The finished product is sponge iron.
In general, the direct recovery process for iron ore is as follows. At the same time, there is always a part of the gas that climbs up and leaves the furnace to be reused as fuel in the next step, the reason being that it contains a lot of carbon dioxide and hydrogen. In addition, part of this gas is returned, and this part of the gas can also be used for methane oxidation.
Advantages and disadvantages of the Midrex method over the direct resuscitation method
The many advantages of the Midrex method make it widely used (approx. 60%) among sponge iron manufacturers. Call it technology.
Because the system is more convenient and the sponge produced is efficient (metallization rate 94-96). On the other hand, the costs associated with repairs can be reduced in this way, which also makes it a suitable investment platform. Another point is that the sponge produced by the Midrex method is more uniform in chemical composition.
Despite all the advantages and benefits of the Medrex method, it is clear that it also has some disadvantages. One of the disadvantages: the sponge iron produced by the Midrex method is harder than other methods. This means that this method will require a lot of initial energy at the start.
Another important point is the erosion of the furnace body over time. Of course, this chassis is attached to a certain extent, and the method of attachment is insulation.
Production of sponge iron by the HYL method
This mechanism was invented in the early 1950s.
Designed as an experiment, with a nominal capacity of 2 tons per today, the first problem on the way to the test was that the process did not succeed in achieving the necessary regeneration, after 18 months of research and study, and finally after applying several changes, the most important of which is to return to system changes. Created the first system for the direct reduction of iron ore and the HYL process for the production of sponge iron.
It was, of course, introduced as an experiment in mid-1955. The experiment was successful, and the production capacity of sponge iron gradually increased, and in the last days of the process of research, the system could produce 60 tons of sponge iron per day in an optimized way.
In this mechanism, the separated natural gas (after removing the reformer) is used. This natural gas is one of the regenerants similar to the Midrex method. In addition, they also considered the use of steam to produce hydrogen reduction gas and increase the composition of the reduction gas. In this mechanism, the hydrogen content of the reducing gas composition is much higher than carbon monoxide.
There is also a significant reducing factor, hydrogen gas. The furnace for this method is the same as the vertical shaft Midrex style. The sealing of the furnace is done by mechanical (hydraulic) activities, the pressure in the reaction environment is much higher, it can be adjusted up to 7 atmospheres, this is to achieve the speed of the direct regeneration reaction.
Application of sponge iron:
Sponge iron is a suitable substitute for iron scrap and therefore a high percentage of raw materials can be produced using this material instead of using scrap to provide the smelting required by steel mills. One of the most important applications of sponge iron is induction furnaces.
In an induction furnace, almost 50% of the sponge iron can be replaced with scrap. Remember, of course, that using it in an induction oven requires technical knowledge and experience. In addition, sponge iron has brought about major changes in the continuous casting of the steel industry.
What are briquettes?
The briquettes are sponge iron or DRI. The difference is that it is formed closely during the production process, and is divided into the following three types according to type and temperature in the production process.
Types of briquettes:
- Hot sponge iron ball
- Soft sponge iron ball
- Cold sponge iron ball
The manufacturing process of sponge iron
Using coal to produce sponge iron involves the reduction of iron ore with coal or lignite. The reduction is carried out in a rotary kiln at a predetermined temperature and in a controlled atmosphere.
The incoming raw materials, i.e. iron ore, coal, and limestone, enter the rotary kiln in the desired gauge size, which is poured and rotated within the required speed range. Due to the tilting and rotating motion of the furnace, the raw material moves from the feed end to the discharge end.
During this process, it is preheated and converted into sponge iron. The material discharged from the furnace is transferred to a rotary cooler where the material is cooled.
The cooled product is discharged from the cooler at a temperature of approx. 800 degrees Celsius and transferred to the product separation and handling system. The product is composed of non-magnetic sponge iron such as coal, which is sieved into parts of different sizes and then magnetically separated by a magnetic separator.
The sponge iron was brought to the storage box to be shipped. Coal, which is non-magnetic, and contains a certain amount of carbon, is placed in separate bins and, if found suitable, can be recycled or sold as a fuel for applications such as brick making.
direct reduced iron market chart
As a strongly reducing species, DRI or direct reduced iron market chart tends to reoxidation, which is an exothermic reaction. Therefore, there is a risk of self-heating and fire if appropriate precautions are not taken during handling, handling and storage.
Application of iron sponge
DRI has a slightly higher iron content, which tends to make it more suitable for use in electric furnaces. In addition, gases released during sponge iron production can be collected and used in a number of other applications. This byproduct of the ironmaking process helps offset the costs of iron production and also helps sustain other processes that require natural gas to function properly. It can also be used to make powdered ores that work well when mixed with other metals to make various iron-based products.
One of the most common uses of sponge iron is to make wrought iron. This type of iron can be used to make decorative items around the house, such as decorative grills for screen doors, railings for windows, and even various wall coverings.
Sponge iron is also often used to make components used to make durable lawn and garden furniture. Wrought iron furniture, if handled correctly, can easily withstand the deterioration of the weather and can last for many years.
Improvements in the production of sponge iron in recent years have made it possible to reduce iron without melting the ore. Because iron can be made into pellets or even powders, it is an economical and useful alternative to scrap metal, which is sometimes used by steelmakers. Very little time and resources are required to produce sponge iron. Therefore, the fact that it can be quickly mass-produced only increases the benefits of these iron products.
Overview of sponge iron applications
- All or parts of the raw materials for the production of pig iron and steel
- Steel construction with hard gauges
- Ideal for deep drawing bearings that require absolute freedom from impurities such as copper, nickel, molybdenum, tin and arsenic.
- Commercial high-grade steel is produced directly from compressed sponge iron powder in an electric arc furnace.
Minimize the nitrogen content of steel. The higher the amount of sponge iron in the charge, the lower the nitrogen content of the final product. The presence of nitrogen has an important effect on the steel’s high temperature brittleness, magnetic properties and impact strength.
Precipitant in copper-lead metallurgy
Direct regenerated iron benefits
Sponge iron has several advantages and can effectively compete with other types of cast iron. You are dealing with the actual ingredients in the final product itself. For example, this iron is more abundant than pig iron, another type of iron commonly produced in blast furnaces.
- There is less sulfur in sponge iron. In the direct reduction method of iron, inferior coal can be used, which is not suitable for the production of ordinary iron.
- It is an alternative to steel scrap produced through EAF/IF lanes.
- It is an excellent raw material for electric furnaces used in various factories, enabling factories to use less scrap or produce higher quality steel.
- Sponge iron is a core material used in the manufacture of various steel types such as the highest quality TMT bars, DI pipes, and more.
- Steelmaking scrap is very useful for small steel mills because it acts as raw material.
- Sponge iron is an excellent material for use as a coolant for LD converters in integrated steelworks.
- Less noise during melting
- Easy to transport and move
Direct reduced iron production method
1- Natural gas-based production
The production and manufacturing process of sponge iron takes place from natural gas using Purofer, HYL, and Midrex methods. Meanwhile, HYL and Midrex methods are widely used due to their high efficiency.
Based on the Midrex method, recovery of iron ore using frac gas without intermediates. In this method, natural gas releases carbon monoxide and hydrogen with the help of heat as it breaks down in a gas cracker.
After this process, the spent gas enters the reduction furnace and combines with the oxygen in the molten iron to reduce the iron ore. The product obtained through this process is DRI or sponge iron.
In the HYL process, in addition to natural gas, steam is used to increase the amount of hydrogen. Compared to carbon monoxide, increasing the amount of hydrogen causes the iron ore to regenerate. The regeneration furnace used in this method is the same as the Midrex method.
2- Coal-based production
There are two modes of operation for this method: tunnel furnace and SL/RN. Although the tunnel kiln has a long and tall structure, it is made of refractory bricks. This DRI production method is carried out in three processes of cooling, regeneration and preheating.
First, the iron is pulverized into powder, placed next to the coal material as it passes through the tunnel, and regenerated under the influence of the heat generated by oxygen and combustion of natural gas. As one of the old iron recovery methods, the SR/NL method combines coal feed with thermal coal in a furnace to produce and manufacture sponge iron.
Uses and applications of sponge iron
The use in the steel production industry can be counted as one of the most important uses of sponge iron. Steel made from this material is used in a wide variety of industries, including tools and parts, automotive manufacturing, and more. Use in induction furnaces is one of the other uses of sponge iron.
This product is considered a practical and efficient raw material for the production and manufacture of pure iron and steel in induction furnaces. Applications in the foundry industry are one of the other uses for this product.
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