Novel Binders and Methods for Agglomeration of Ore

Abstract

Many metal extraction operations, such as leaching of copper, leaching of precious metals, and reduction of metal oxides to metal in high-temperature furnaces, require agglomeration of ore to ensure that reactive liquids or gases are evenly distributed throughout the ore being processed. Agglomeration of ore into coarse, porous masses achieves this even distribution of fluids by preventing fine particles from migrating and clogging the spaces and channels between the larger ore particles. Binders are critically necessary to produce agglomerates that will not break down during processing. However, for many important metal extraction processes there are no binders known that will work satisfactorily at a reasonable cost. A primary example of this is copper heap leaching, where there are no binders currently encountered in this acidic environment process. As a result, operators of many facilities see a large loss of process efficiency due to their inability to take advantage of agglomeration. The large quantities of ore that must be handled in metal extraction processes also means that the binder must be inexpensive and useful at low dosages to be economical. The acid-resistant binders and agglomeration procedures developed in this project will also be adapted for use in improving the energy efficiency and performance of a broad range of mineral agglomeration applications, particularly heap leaching. The active involvement of our industrial partners will help to ensure rapid commercialization of any agglomeration technologies developed by this project.

Recent Progresses in GaN Power Rectifier

“…6) Among them, gallium nitride (GaN), with its wide band gap, high electrical critical field and high saturation velocity (even higher than for SiC) seems to be an excellent candidate for power devices with higher performances in terms of current density or reverse breakdown voltage. [7][8][9] Extensive efforts have been made to achieve high-quality GaN layer grown by heteroepitaxy on sapphire and silicon wafers, [10][11][12][13][14] leading to structures now compatible with rectifying devices at more reasonable cost. If an abundant literature can be found on both ohmic and rectifying contacts, [15][16][17][18][19][20][21][22][23][24][25] central parts of the Schottky devices, few papers present complete structures and their performances.…”