Title of Invention

A PROCESS FOR PRODUCING IRON ORE SINTER WITH LOW REDUCTION DEGRADATION INDEX

Abstract

The present invention provides a process for producing iron ore sinter from ore fines, fluxes, coke fines other in-process solid wastes generated in an integrated steel plant, with low reduction degradation index (RDI) by controlling the wind box temperature below the sinter strand, so that the maximum wind box temperature is equal to or greater than 300°C so that an RDI value of less than 28 can be achieved.

Full Text

FIELD OF THE INVENTION This invention relates to a process for producing iron ore sinter with low reduction degradation index (RDI). BACKGROUND OF INVENTION Iron ore sinter is the agglomerate produced from ore fines, fluxes, coke fines and other in -process solid wastes generated in an integrated steel plant. In recent years, sinter has earned the status of most preferred charge material for blast furnaces. Indian blast furnaces use 50-70% sinter in burden due to high RDI. The reduction degradation index (RDI) is an important property of sinter, which is a measure of its amount of degradation under a reducing atmosphere at 600-800°C as exist in the upper stack region of a blast furnace, Thus , blast furnace sinter burden cannot be increased unless impro vem ent of RDI is m ade. Control of RDI is one of the most challenging tasks before a sinter maker, because of its interdependence on chemical as well as micro structural properties of sinter. Under Indian conditions the task becomes doubly difficult due to high Al2O3 content, led by an unfavourable Al2O3/SiO2 ratio in most Indian ores. Moreover, the existing blast furnaces do not allow high driving rate. Thus residual time of sinter in upper stack region is longer, putting more emphasis to have low RDI in sinter. OBJECT OF THE INVENTION One object of the present invention is to propose a process control of important parameter/s in a sinter plant to control RDI of agglomerate produced from ore fines, fluxes , coke fines and other in-process solid wastes generated in an integrated steel plant. Another object of this invention is to propose a process to produce sinter of improved RDI using Indian iron ore fines and thereby maximizing the productivity of Indian blast furnaces. One more object of this invention is to propose a process to produce sinter with lower standard deviation of RDI value the production plant, so that the operation at blast furnace can be improved further. Further object and advantages of this invention will be more apparent from ensuing description. At the outset of the description it is to be understood that the ensuing description is only illustrative of a particular form of the process of the invention. However, such a particular form is only an exemplary embodiment and without intending to imply any limitation on the scope of this invention. Accordingly, the description is to be understood as an exemplary embodiment and reading of this invention is not intended to be taken restrictively. DESCRIPTION OF THE INVENTION According to the present invention there is provided a process for producing if iron ore sinter with low reduction degradation index (RDI). The sinter agglomerate is produced from ore fines, fluxes, coke fines and other in- process solid wastes generated in an integrated steel plant. The reduction degradation index (RDI) of the sinter is controlled by controlling wind box temperature below the sinter strand such that the following criterion is fulfilled. To maintain Maximum Wind Box Temperature (also called the burn through temperature) above 3Q0°C to achieve RDI value below 28 under steady state of plant operation. Here steady state means the plant should run without interruption for at least 4 hours, during which 3 increments of sinter sample is collected, Trial at sinter plant Tata Steel during a period of 54 days has resulted in sinter with RDI less than 28 by maintaining windbox temperature of 300- 3200C. A drop in average RDI by both magnitude and standard deviation has been observed during this trial run of the plant. The result has been illustrated in the table given below to substantiate the claim made by the inventors. 1. A process for producing iron ere sinter with low reduction degradation (RDI) by controlling the wind box temperature below the sinter stand through changing in trimming Coke breeze \n continuous mode so that the maximum wind box temperature is attainable in the range of 300- 320°C. 2. The process as claimed in claim 1 wherein a maximum wind box temperature is attainable in the range of 300-320°C, the RDI value achieved in range of 27-28. 3. The process as claimed in claim 1 and 2 wherein with a maximum wind box temperature in the range of 300-320°C, a tower standard deviation of RDI value 0.5-1.0 is achieved. The present invention provides a process for producing iron ore sinter from ore fines, fluxes, coke fines other in-process solid wastes generated in an integrated steel plant, with low reduction degradation index (RDI) by controlling the wind box temperature below the sinter strand, so that the maximum wind box temperature is equal to or greater than 300°C so that an RDI value of less than 28 can be achieved.

Documents:

513-cal-2002-granted-abstract.pdf

513-cal-2002-granted-claims.pdf

513-cal-2002-granted-correspondence.pdf

513-cal-2002-granted-description (complete).pdf

513-cal-2002-granted-examination report.pdf

513-cal-2002-granted-form 1.pdf

513-cal-2002-granted-form 13.pdf

513-cal-2002-granted-form 18.pdf

513-cal-2002-granted-form 2.pdf

513-cal-2002-granted-form 3.pdf

513-cal-2002-granted-form 5.pdf

513-cal-2002-granted-gpa.pdf

513-cal-2002-granted-reply to examination report.pdf

513-cal-2002-granted-specification.pdf