From lesson three to lesson six, we learned about whole steel production route. And in the first part in lesson three, we learned about iron-making and raw materials. The next lesson, we'll discuss about steel-making and the last session we'll discuss about casting and rolling. In this lecture, we first talk about what is difference between iron and steel. Then, this lecture is for the iron-making. We first discuss about raw materials for iron-making reactions. And we describe what is the reactions and what happens inside reaction furnace called blast furnace. And the last part, we probably discuss about environmental issues for iron-making and next generation of iron-making process. This shows whole iron and steel production route. You first start with raw materials, and raw materials first pretreated. Then, it is delivered into blast furnace. The main iron-making reaction happen here. Then, produced iron is delivered into steel-making plant. The iron is converted into steel. The steel is further refined and cast. So with this step, we made semi-final product. This semi-final product is also further treated. So, into rolling process. Then, steelmakers sell this type of final product. In this lecture, we go to first part, raw material and iron-making process. Now, let's first talk about the difference between iron and steel. We typically use these terms simultaneously. But in Ferrous Technology, iron and steel are different. First, let's talk about iron. In science point of view, iron is just a chemical element, with symbol Fe. This appears in periodic table and is atomic number 26, but this is just purely scientific term. Then, we could mention the product iron and the product steel. There are two types of iron. The first one is wrought iron. This is the old versions iron product. This was made in ancient time at lower temperature and it contains low carbon content. So, its close to almost 100% Fe. This is quite soft and malleable. This was produced when iron-making and steel-making technologies have not been developed yet. In these days, this type of wrought iron is no more used. In modern iron-making plant, we produce pig iron. This we call iron. It contains certain amount of carbon. Its carbon content is about 3-4 or even more than 4%. This is produce from blast furnace by smashing iron or with coals. This is of course hot metal when this is in molten state. If we cast this type of pig iron, then we call it cast iron. However, the application period of cast iron is quite limited, because cast iron is quite brittle. In a few tries, this kind of iron more useful, when you take carbon out of this iron. So once carbon content in iron is decreased, then we call this state steel. Steel is actually converted from hot metal by the great carbon content and other impurities. Then, since iron and steel are different, so the production route for iron and steel are also different. This table shows different characters of iron-making process and steel-making process. First, look at iron-making. The raw material for iron-making process is iron ore. This is basically iron oxide. Through iron-making process, we produce hot metal, this is liquid iron containing certain amount of carbon. How do you produce hot metal from iron ore? Since iron ore is iron oxide, so we first take oxygen out of iron ore. What would be an effective chemical element to take oxygen from iron ore? This could be carbon. Carbon is Supplied from coal. So iron ore and coal links together to produce hot metal. Whole this process should be carried out under reducing conditions because oxygen is taken out. On the other hand, in steel-making process, we use this hot metal as raw materials for steel-making in order to produce liquid steel. Difference between the hot metal and steel is carbon content. So, by decreasing carbon content in hot metal, we produce liquid steel. In order to decrease carbon content, what would be an effective chemicals? This could be oxygen. So by blowing oxygen to hot metal, the carbon content could be lowered. So it means, liquid steel is made under oxidizing condition. This is quite different to iron-making process. And also some difference is the temperature. In iron-making process, raw materials, iron ore and coals, are delivered from room temperature and its temperature increases inside reaction vessel for iron-making over to seven degree Celsius. In case of steel-making, the hot metal temperature delivered to steel-making plant is about 17 degrees Celsius. During steel-making process, it increased up to 17 degrees Celsius. Temperature level is also different. And the biggest difference is the operation type. In iron-making process, raw materials are continuously delivered to reaction vessel and products, hot metal, are also tapped continuously. This is really a continuous process. On the other hand, the steel-making plant, there are several different types of steel-making reaction required. So for each reaction, different reaction vessels are required. So liquid steel is contained in different reaction vessels and reactions are carried out separately. So this is batch type process. There's a big difference between iron-making and steel-making.
