Degradation characteristics of steel making materials during handling

The degradation characteristics of various ores and coal types due to particle breakage have been studied by a number of researchers to determine the causes of degradation and its prevention during the handling process from mines to end users. They have used several drop tests to determine the degradation characteristics of each ore and coal such as: critical drop height tests; cushioning tests; different types of impact surface tests; different sample sizes tests; stabilization tests; weathering tests and volume breakage index tests. Researchers have also used a tumbler drum test to measure the attrition or abrasion properties of the material during handling.This review highlights that the fines generation increases during transport from mines to end users due to more large vertical drops, replacing the larger vertical drops with smaller drop heights reduces the fines generation, the cushioning effects with initial fines reduce the degradation of lump size ore during handling, the different impact surfaces have different degradation characteristics, the stabilized ore produced less percentage of fines than the normal ore during handling and the rate of fines generation of coal increases with the period of weathering. The rate of degradation is higher in larger lump size coal compared to smaller lump size. The lump coal dropped from lower heights does not follow a first order breakage process behavior. Volume breakage decreases with the increases of the sample mass.A degradation model was developed with several parameters to predict the total fines generation of bulk materials during handling. The model has the following dimensionless parameters: height parameter, cushioning parameter, surface parameter, stabilization parameter and weathering parameter.

Two microencapsulation processes namely solvent evaporation and complex coacervation are used to produce two kinds of microparticles: microspheres and coated microspheres loaded by pesticide model. These microparticles are characterized by several techniques (SEM, IR, size and size distribution and pesticide release).Figure optionsDownload as PowerPoint slide