Taneomi Harada

Mineralogical properties and fundamental mineral processing behaviour of the chromite contained in laterite leach residue

Abstract In order to utilize chromite in the laterite residue discharged from the large-scale Ni-leaching plant in the Philippines, its state of distribution, mineralogical properties, grindability, floatability, and magnetism were investigated. Chromite particles are concentrated over a 37μm size range, and poor in liberation. There are three different groups of chromite (A, B, and C), categorized according to their polished section, chemical composition, lattice constant, and specific gravity. Some of these differences affect the mineral processing behavior to a considerable degree. The grindability of chromite in leach residue is relatively high compared with that of chromites from other regions. Flotation is controlled by interfacial electrical attraction when ionic collectors are used, and the flotation peak appears in the vicinity of the PZC when NaOl is used. The order of floatability among the three groups of chromite particles is A>B>C, which indicates that a difference in surface structure by group affects floatability. Chromite from leach residue reveals paramagnetism at room temperature. The higher the solid solubility of magnetic ions (Fe 2+ , Cr 3+ , and Fe 3+ ), the greater the susceptibility is. In other words, the susceptibilities among the three groups are in the order of C>A>B.

The role of resource recycling

Resource recycling reduces the amount of waste discharged into the global environment. The waste reduction achieved by thorough recycling is substantial. Recycling is thus an inseparable part of global environmental protection.We human beings have used mineral resources since the birth of our species. The quantities and increasingly complex forms in which mineral resources have been used at different times in our prehistory and history serve as indices of civilizations advancement. But on the eve of the 21st century, environmental pollution and global warming stemming from spiraling resource and energy consumption pose serious dilemmas for humanity. The rapidity with which our resource consumption has increased approximates exponential growth.The worsening condition of the earths environment because of massive resource and energy consumption is the result of activity at many stages of production, from the mining of mineral resources to the manufacture of finished products; the culmination of the process is the disposal of products as waste after their use. As we shall see from examples given in this paper, efforts are being made to solve this problem through recycling; but in many areas the problems remain incompletely solved or unsolved altogether.