A comparative study on the effect of chemical additives on dry grinding of magnetite ore

Abstract

Dry grinding as an alternative to wet grinding is one of Sweden's strategic research areas to promote dry beneficiation. However, dry grinding has remained unpopular due to its higher specific energy consumption (Ec), wider particle size distribution (PSD), difficult material handling, and purported effects on downstream processes. In this work, the effects of the new additives (Zalta™ GR20–587, Zalta™ VM1122, and Sodium hydroxide) employed as grinding aids (GA) on dry grinding and product characteristics of a magnetite ore were studied in light of possible downstream effects. The grinding efficiency of Magnetite increased after using GAs in comparison without the GAs; however, an optimal dosage exists for each of the chemical additives investigated. Comparing to grinding without GA, Zalta™ VM1122, a viscosity modifier was selected as the most effective GA where by using this GA; the Ec decreased by 31.1% from 18.0 to 12.4 kWh/t, the PSD became narrower and finer (the P80 decreasing from 181 to 142 µm), and the proportion of the particles (38–150 µm) increased from 52.5 to 58.3%. Zalta™ VM1122 resulted in increased surface roughness and minimum microstructural defects. Further, it was found that Zalta™ VM1122 resulted in similar zeta potentials and pH values for the product compared to grinding without GA. These comparable product properties are advantageous as they minimize any potential negative effects on all possible downstream processes such as flotation.