Blast furnaces are metallurgical structures that are designed to produce metals as well as lead and copper. The term “blast” is used to describe the combustion air that is usually forced into the unit at pressures above the atmospheric pressure.
Blast furnaces are prone to different kinds of issues including breakouts, channeling, and scaffold formation. Often, these issues can threaten the productivity of the unit and the safety of those who operate it. Thankfully, there are licensed companies that can assess such issues and carry out the necessary blast furnaces repairs with the right tools and technologies.
In this article, we will explain the difference between the electric arc and the blast furnace. We will also explain the kinds of blast furnace repairs that there are.
But, first, let’s get into more details about how a blast furnace functions so we can truly operate on the same page.
How a Blast Furnace Works
A fully functional blast furnace receives a continuous supply of fuel (coke), flux (limestone), and ores from the top of the unit, while a blast of hot hair which may be enriched with oxygen is sent into the lower part of the unit simultaneously.
The hot air that goes into the lower parts of the furnace goes through different pipes collectively referred to as tuyeres. This compressed hot air will then react with the materials that were fed into the furnace and cause the smelted metal to fall to the bottom. The final products of the chemical reaction are usually slag and molten metal. These products often fall to the bottom within six to eight hours after they are injected into the unit, while the waste gases, also known as flue gases, will exit the unit from the top.
The term “blast furnace” is commonly used to describe structures that are used to convert iron ores to pig iron. However, going by the processes that occur in these metallurgical structures, bloomeries used for smelting iron, as well as, blowing houses used for lead can be classified as a blast furnace. This is because their processes are similar.
Blast Furnace Repairs: Manual vs Automatic
When it comes to repairs on furnaces, manual or automatic solutions may be used. The manual approach often requires skilled repair specialists to operate under hot conditions in the unit.
Here are some of the repairs that can be done manually:
- Stopping the unit and reducing its burden.
- Opening the probe holes and doors.
- Gunning the insulation plug.
- Breaking the insulation plug.
- Cleaning the walls thoroughly.
- Evacuating the rebound.
The automatic approach is often done with the aid of special robots and is recommended for quick and emergency interventions.
Here are some of the repairs that a robot can do:
- Demolishing the insulation plug.
- Gunning.
- Cleaning the walls
- Gunning the insulation plug.
However, service companies tend to prefer the manual approach to the automatic one because the latter is limited in scope. More so, the manual approach has proven to deliver better results.
For instance, when cleaning the walls of the unit, a robot only does a superficial cleaning and one may not be able to assess the cleanliness afterward. Whereas, a specialist who will go into the unit can do a thorough job on the bosh and other aspects of the furnace.
What’s more? During the gunning process, which is after the floor installation, specialists can work with multiple machines at the same time. A robot can’t do this. This makes the manual approach more productive than the automatic approach.
More so, a specialist can ensure a lower rebound percentage because they can ensure correct estimates of the distance between the wall and the nozzle.
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Blast vs Electric Arc Furnace
When steel production is mentioned, oftentimes you can bet that the production process involves the use of a blast unit or an electric arc unit.
While you will get the same final products – steel – from these two metallurgical units, there are some cases where one may be preferred over the other.
So, what are the differences between a blast and an electric arc furnace?
For starters, an electric arc furnace uses scrap steel as its major raw material. It also runs primarily on electricity. In terms of the cost of production, its initial cost is often low. This unit also takes up relatively less floor space for installation. What’s more? It takes far less time for it to produce the desired products.
A blast furnace, on the other hand, utilizes iron ore as its raw material. It also uses coke as its primary source of fuel and energy and melts the ore into carbon-rich pig iron which is further processed in a converter to extract impurities. This furnace type is cost-intensive and is known to take up large floor spaces. However, compared to the electric option, it produces cleaner steel.
Because they run on electricity, it is easier to control the temperature in electric arc units than it is in a blasting unit. This makes the electric arc more efficient.
Conclusion
Blast furnaces are commonly used in the steel industry to convert iron ores to pig iron in a bid to meet up with the global demand for clean steel. But these metallurgical units are also prone to damage.
Damage or fault in a blast furnace can become a safety risk and affect operational productivity. Such faults include furnace slipping and hanging, scaffold formation, and channeling.
If the unit starts to show operational irregularities, the services of a repair company will be required. A good repair company can assess the problem and provide the necessary solution to reduce downtime and ensure the safety of lives and properties.
While automatic repair services (repairs with the aid of robots) exist, the manual approach has proven to be a more reliable option with better results. It is the limitations of the robot-aided approach that makes manual services widely recommended for repairs.
