User:Jsgau/Corex Process

Corex Process is an environmentally friendly metal refining process that turns iron ore into usable metal. Created in 1989, the Corex Process is the first commercial ore reduction process that was a different choice than a blast furnace. The Corex Process is a two step process that goes through the Reduction Shaft and then the Melter-Gasifier. Usually, the process of smelting and reduction of ore requires so much coal that the Corex Process uses a different fuel in order to go through the process faster than before. Created by Siemens VAI, the process was more environmentally friendly and fuel efficient than previous methods. With its world-wide success of its environmental effects and efficiency, Corex Process plants are built in various countries to smelt ore.

History

The Corex Process first started in the mid 1980s by the Voest-Alpine Industrieanlagenbau (now Siemens VAI Metals Technologies), located in Austria which focused mostly on building plants for iron and steel production. It was tested continuously in Germany and was continuously improved. The success of the first plant gave the company confidence in expanding worldwide, starting with South Africa.

Process

Reduction Shaft

The first step of the Corex Process is to put the ore into the Reducation Shaft. A small amount of coal is then added into the shaft in order to prevent the ore from sticking to the sides and the bottom of the shaft. The reduction gas is then injected into the shaft through a tube with temperatures approximately 850 degrees Celsius.

With a constant flow of gas, the shaft continues to reduce the ore until it is over 95% metalized. When the ore reaches that percentage, the ore is then discharged, or dropped from the reduction shaft into the Melter-Gasifier. The time it takes for the ore to pass through the Reduction Shaft mainly relies on the quality of the reduction gas flow, the temperature of the gas, the reduction rate of the ore, and the average size of the ore.

Melter-Gasifier

When the ore is placed into the Melter-Gasifier, the metal is already around a temperature of 600-800 degrees Celsius. Through pipes, the metalized ore is distributed evenly along the circumference at the top of the Melter-Gasifier in order to make sure the ore is spread out evenly. It is then placed on a platform where non-coking coal is continuously used to heat up and pressurize the metal.

Through the use of pure oxygen, it is injected into the Melter-Gasifier to generate CO. This hot gas is used for melting iron, ore and other metallic sources. The temperature of the Melter-Gasifier ranges from between 1,000-1,100 degrees Celsius if the area is maintained properly. All the dust that is recycled by collecting it through pipes into four different dust burners that combust the dust and provide additional oxygen.

The gas inside the Melter-Gasifier is then cooled to a temperature of 850 degrees Celsius. The remaining gas is then put back into the Reducation Shaft to be used to pressurize any additional ore still in there. The gas that is released into the atmosphere has a high calorific value which means that it can be used for a range of ideas including power generation.

Advantages

The Corex Process uses regular coal that can be bought in stores for camping trips instead of coking coal. It focuses less on blast furnaces and uses gasification by using pressure to metalize the ore that is placed in. By eliminating the use of coking coal in the process of smelting ore, the process gains two environmental advantages. The first is that without the use of coking coal, coking plants don't need to be built to produce it. Therefore, the byproducts from the process of making coking coal like benzene and other harmful gases, are not created. Secondly, the dust products that are usually released into the atmosphere and such are able to be used as fuel to provide more oxygen for the process. Also, the emissions that the Corex Process gives out is significantly less than other methods. The max amount of Nitrous Oxide the Corex Process will give out is about 14 grams while the blast furnace will give out a maximum of over 2,000 grams. The Corex Process also emits less dust and Sulfurous Dioxide compared to a regular blast furnace.

For every 1000 kg of metal, the C-1000 Corex Plant uses about 0.88 tons of non-coking coal, 0.71 tons of oxygen, and 60 kiloWatts of electricity. The Corex Plant manages to lower production costs 15%-25% compared with regular blast furnaces. It is compatible with a wide range of ores and coals and it takes away the use of coking plants because of the very small amount of coking coal used in the process.

Disadvantages

Despite all of its advantages, the Corex coal uses a lot more coal than any other iron making method, making the process a little expensive. It also requires a lot of maintenance and is a very sophisticated system. The use of such a large amount of gas and hot metal transfers also makes the process hazardous at times.

Usage

Through the usage of the Corex Process, the COREX company focused on creating plants that would implement these new innovative systems. There are the C-1000, C-2000, and the C-3000. The second C-3000 was put into operation in China in 2011 while there are even more plants such as the C-2000 in South Korea, India and the United States. In 2010, the Siemens Company had managed to successfully build a second C-3000 plant while lowering the amount of fuel from 970 kilograms to 840 kilograms.

The initial success of the COREX plant allowed the production of a larger plant to be built in South Africa by Saldanha Steel. This new plant, called the C-2000, was able to produce over 650,000 tons of metal per year. In 1995, a C-2000 plant was built in the Republic of Korea making 600,000-700,000 tons of iron and steel per year.

In November of 2007, a Chinese steel company called Baosteel Pudong Iron and Steel Co. Ltd. near Shanghai started a C-3000 plant which would have the capacity of 1.5 million tons of metal per year. In just a little over 2 years, the plant was completed.

The latest Corex plants are ideally used for initial metal for other steel works projects and mills. Due to the continuously increasing demand for steel, the Corex plants provide an answer to coking coal shortages.