How a Steel Plant Used Sinter Feed Analysis to Get More Out of Iron Ore

Iron ore is important to almost every industry and to every day modern life. The primary use of iron ore is to make steel, and steel can be found in everything from buildings, to aircraft, to cars, appliances, tools, and more.

According to the U.S. Geological Survey, Mineral Commodity Summaries, January 2020, “iron ore resources are estimated to be 110 billion tons of iron ore containing about 27 billion tons of iron. U.S. resources are mainly low-grade taconite-type ores from the Lake Superior district that require beneficiation and agglomeration prior to commercial use. World resources are estimated to be greater than 800 billion tons of crude ore containing more than 230 billion tons of iron.”

AT Minerals Processing reports that the EU has 9 member states producing iron ore, including Sweden, Norway, Austria, Slovakia and Germany. “On a world scale, the quantities produced are low. Since the iron ore is extracted in underground mines…, mining costs are hardly competitive compared to the open pit mines of, for example, Australia or Brazil. As a consequence, the low iron ore prices have been very problematic for mining companies.”

Before all that iron ore can be turned into steel, it must go through the sintering process, which is the step between mining iron ore and steelmaking. The U.S. Environmental Protection Agency explains that the sintering process converts fine-sized raw materials, including iron ore, coke breeze, limestone, mill scale, and flue dust, into an agglomerated product, sinter, of suitable size for charging into the blast furnace.

Sinter quality begins with the mined iron ore and the proper selection and mixing of the raw materials. Inhomogeneous raw mix can affect permeability and cause an increase in fuel consumption. That’s why it is important that the material be analyzed to determine the elemental composition of the bulk raw materials in sinter feed.

Hüttenwerke Krupp Mannesmann GmbH (HKM) in Duisburg, Germany, a subsidiary of Thyssenkrupp Steel Europe AG, produces up to 5.1Mt/yr of sinter and 5.4Mt/yr of steel. Six years ago, the company upgraded to an online sinter feed analysis system that uses prompt gamma neutron activation analysis (PGNAA) to determine elemental concentration in bulk materials. (If you want to know more about the technology, visit our PGNAA and PFTNA Technology page.)

This non-contact, non-destructive method measures through many centimeters of material, so it’s ideal for real-time analysis of bulk materials on conveyor belts. Because the entire process stream is analyzed, the errors potentially associated with mechanical sampling of the final sinter product can be reduced.

This online elemental analyzer has allowed HKM to validate sinter composition and quality more efficiently and cost-effectively. Instead of taking hours from sample to result, they now see chemistry information each minute on a real-time basis, enabling plant operators to make quicker, better informed decisions to control the basicity of the sinter. For HKM, the sintering process has become significantly more uniform, which has translated to higher performance. The more uniform sintering process has yielded cost savings by helping to increase the volume of sinter going to the blast furnace, lowered the return fines of the sinter, and reduced fuel consumption.

Overall, HKM saw a return on investment in less than a year – an important factor when iron ore prices are problematic.

You can read the more details in this year’s Steel Times International article, Improving sinter feed analysis

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