Why are laterite ores difficult to concentrate before smelting?

Laterite ores are difficult to concentrate before smelting primarily because they are oxide ores, which are not amenable to conventional concentration processes. Unlike sulfide ores, which can often be concentrated, the nature of laterites necessitates that large tonnages of the raw material be processed directly in smelters.1

Furthermore, these ores present significant processing challenges due to their high water content, which ranges from 35 to 40 percent. This moisture includes both free water and chemically bound water in the form of hydroxides, requiring extensive drying and dehydration operations in large rotary-kiln furnaces before the ore can be reduced to nickel metal. Because of these factors, the range of available process options for laterite nickel processing is inherently limited.1