Technology of Coal-based Direct Reduction Iron(5)——ITMK3 method
ITMK3 is the so-called "third generation" ironmaking technology jointly developed by Kobe Steel and MIDREX.
1. Features of ITMK3 process
● The reduction time is short, and it is known for the short time for producing granular iron. Reduction, slag iron, semi-melted iron coagulation, and slag removal are completed within 60 minutes. In contrast, blast furnace iron making requires 20h, and gas-based direct reduction process requires 8h. The short reduction time also makes it easy for the device to start up, stop production, and adjust output.
● High-purity iron products are obtained in one step. The composition of small iron particles is 96%-98% metallic iron, 2%-4% carbon, and the iron content is close to that of blast furnace pig iron.
● The process flow is short and saves investment. The process investment is about half of the traditional blast furnace iron making process flow.
● Using high-grade fine iron powder and natural gas as the main raw materials.
2. The main purpose and problems of the ITMK3 process
The main goal of ITMK3 ironmaking technology is to increase the temperature in the late stage of RHF reduction, realize the separation of slag iron in a semi-melted state, and directly produce granular iron. If it succeeds, it is a very economical and environmentally friendly new technology.
The granular iron process involves a phase change process, and the actual production factors are very complex, such as the reducibility of iron ore, the influence of the composition of carbon-containing pellets on the melting point of the slag and the mass transfer of iron elements, the temperature control of RHF, and the slag Iron separation conditions, the control of harmful elements in the product, the adhesion and erosion of the charge and the furnace bottom, the formation of granular iron without agglomeration, the outflow of molten charge will affect the normal operation of the furnace bottom and the discharge machine, etc. Therefore, for the commercialization of this process to succeed, a technological breakthrough is required.
Japan kobe steel construction ITMK3 demonstration unit in the United States in 2004, the original plan is put into production in 2006, due to meet slag iron separation temperature refractory material and base appear problem, grain of high sulfur content in iron products, iron grain generated such as required for the cooling time is too long, make the production efficiency is far less than design ability and other engineering problems.
