Mitigating the deleterious effect of clay minerals on copper flotation

Abstract

Clay minerals have a deleterious effect on the mineral flotation process. Generally, two major phenomena are observed in industry when processing high clay ores: no froth formed on the top of the pulp phase and few valuable minerals loaded on the top of froth. This is an ARC Linkage project with support from Pionera, a reagent company manufacturing biopolymers.The objective of the project is to define the different effects of clay minerals on copper flotation, and then to mitigate the deleterious effects of specific clay minerals in copper flotation by biopolymers and other means.In this research, two types of clay minerals, swelling bentonite with a 2:1 structure and nonswelling kaolinite Q38 with a 1:1 structure, were chosen to represent two typical kinds of clay minerals often seen in industrial flotation plants. The influence of bentonite and kaolinite on copper flotation was investigated. It was found that bentonite and kaolinite affected the copper flotation in a different way. Increasing the proportion of bentonite increased the pulp viscosity that reduced the amount of froth on the top of slurry and decreased flotation rate, resulting in a lower copper recovery. On the other hand, increasing the kaolinite content mainly decreased the copper grade by entrainment that is characterised by smaller bubble size and higher froth stability. The different roles of bentonite and kaolinite in the flotation were associated with their unique structure properties. Also, the collector and frother dosage plays an important role in specifying the different effect of bentonite and kaolinite on copper flotation performance.To mitigate the deleterious effect of kaolinite, three lignosulfonate biopolymers from Pionera, DP-1775, DP-1777 and DP-1778 with different structures, were examined. While rheological measurements indicated that these biopolymers dispersed the kaolinite aggregates, a beneficial effect of biopolymers on copper flotation in the presence of kaolinite was not observed. Instead, interactions of biopolymers with the frother appeared to enhance the froth stability and therefore further reduced copper grade by mechanical entrainment. Two-phase foam characterization revealed that the foam height increased in the blends of biopolymers with the frother. The dispersing and foaming abilities of biopolymers were governed by their structure features such as the content of functional groups, the molecular weight and counterions.The three biopolymers, DP-1775, DP-1777 and DP-1778, were also tested to reduce the negative effect of bentonite in copper flotation. Rheological measurements indicated that all of II the three biopolymers could not significantly reduce the pulp viscosity which was dictated by bentonite. This is consistent with the observation that none of the three biopolymers could enhance the copper recovery effectively. Electrolytes were then used to mitigate the deleterious effect of bentonite on copper flotation through reducing the high pulp viscosity.

Slurry rheology in mineral processing unit operations: A critical review

“…Recently, some researchers have used natural polymers to modify the rheology of flotation slurries with clay contents, and in all studies, rheograms were produced to analyze the effect of rheology modifiers. Wei et al used 100 g/t of the dispersant F‐100, a lignosulphonate‐based polymer, to improve copper and gold flotation from a high clay ore, and it was observed that when using stainless steel grinding media, the effect of the dispersant on rheology was not as significant as the increase in copper and gold recovery.…”

Managing clay minerals in froth flotation—A critical review

“…Clay minerals are all fundamentally built of tetrahedral (T) sheets and octahedral (O) sheets that are bonded in certain proportions with various forces and atoms to form clay macrostructure (Brigatti et al 2013). Based on the layer structures and bonding forces of layers, the most commonly occurring clay minerals in ore deposits can be classified into three groups: kaolin, smectite, and illite (Cruz 2016;Wang 2016;Zhang 2016). The structure representative of a mineral in each group is shown in Figure 1.…”

Surface interaction between phyllosilicate particles and sustainable polymers in flotation and flocculation

“…1,2 Phyllosilicates are comprised of layered silica tetrahedral sheets and alumina or magnesia octahedral sheets in varying proportions. [3][4][5][6] They can adhere to the surfaces of target minerals during otation, changing froth stability and rheology and thereby reducing the grade and recovery of valuable minerals. 7,8 Physical and chemical strategies to counteract the negative effects of phyllosilicate clays have led to overconsumption of some dispersants and depressants, lower pulp solid concentrations, high water consumption, and the need for intense agitation prior to otation to lower viscosities.…”