Executive Summary : | Objective: Development of a suitable process for reduction roasting of low and lean grade iron ore fines/slimes in fluidised bed roaster (both in lab scale and pilot scale) Summary: Maximizing the recovery of iron values from lean and low grade iron ores through reduction roasting process using pilot scale fluidized bed roasterfor conversion of goethite and hematite to magnetite; In general, it has been observed that less than 55% of Fe grade iron ore does not respond satisfactorily in conventional beneficiation process. Even more than 55% Fe content iron ore processing, it gives lot of problem in grinding circuit, settling the particles in the thickeners, filtration of concentrate and the tailings and also making green pellet formation. In overall, it does not meet the design capacity of the plant because of the mineralogical differences of the samples. To maximize the recovery of iron values from low and lean grade resources, CSIR-IMMT has done lot of work on different lean and low grade ores by reduction roasting in rotary kiln followed by low intensity magnetic separation processes. The reduction roasting technology developed by CSIR-IMMT, Bhubaneswar using rotary kiln has been transferred to M/s FL Smidth, Chennai for its commercialisation. M/s. JSPL is going to setup the first plant utilising CSIR-IMMT technology on reduction roasting. Further, in the above technology, fines cannot be utilised directly. CSIR-IMMT is also continuing a FBR project for direct utilisation of fines through reduction roasting in fluidised condition. The kinetics and thermodynamics studies are going on at present. Based on the above studies, it is proposed to develop a suitable process for reduction roasting of low and lean grade iron ore fines/slimes in pilot scale fluidised bed roaster.
The main objective is to develop a suitable process for reduction roasting of low and lean grade iron ore fines/slimes in pilot scale fluidised bed roaster to reduce capital and operating cost of the process.
In overall the following challenges could be overcome:
Indian hematite ore contains good amount of clay minerals, which affects the process fluid dynamics reduces the separation efficiency; It is difficult to control the ultrafine generation in the grinding circuit due to fragile nature of ores; Ineffective dewatering of the tailings and concentrate; It is difficult to beneficiate banded types of ore in conventional process with economic feasibility; The high energy requirement for grinding of banded ore. |