Environmentally friendly flotation method increases the mineral yield

Flotation is one of the most important processes for separating minerals in the raw material industry. The achievement of the highest possible mineral enrichment requires the corresponding selection and dosage of reagente-one complex, time-consuming and costly procedure.

Researchers from the Helmholtz Institute Freiberg for Resource Technology (HIF), which is part of the Helmholtz Center Dresden-Rossendorf, have developed a workflow for the economic and ecological optimization and high scaling of flotation reagens. Initial tests on an industrial scale have shown a significant increase in the concentration of valuable minerals and confirmed the effectiveness of the developed approach.

The paper is published in the journal Colloids and surfaces A: Physicochemical and technical aspects.

Within the flotation process, a liquid with finely ground particles is added to gas bubbles, and the bubbles adhere to particles with a water -repellent surface. These rise up with the attached air bubbles and form a layer of foam that can be towed. Mineral particles have different surface properties, but they are the selectively adsorbing reagents that determine, on the basis of which particle gas bubbles can stick.

Different reagents – shelves that trigger a reaction when contacted with certain other substances – are used to increase the efficiency of particle separation. However, the quantification of the potential of new reagents in industrial flotation processes is very expensive and time -consuming.

“Flotation reagents are crucial for the enrichment efficiency. Our knowledge of their effect is often only based on experiments on the laboratory scale. The selection and dosage of reagents was often informal, subjective and empirical, based on experience. However, a reagent system consists of several components whose interactions are complex.

“The easy replacement of a reagent rarely leads to the desired success. Instead, factors such as dosage, application method and interactions with other reagents and minerals have to be taken into account,” says the HIF doctorate Borhane Ben, which explains the challenges.

New workflow, which has been successfully tested for industrial scale-in preparation

In the Cosilflot project, Ben examined the selective separation of Scheelit and Calcit using colloidal silicon dioxide as a reagent. The experiments were statistically planned, optimized numerically and processed digitally, so that a large number of flotation tests could be excluded at an early stage and the optimal dosing areas of the individual reagents on an industrial scale were quickly determined.

The methodology was successfully tested in an industrial plating system in Europe, in which an increase in the valuable mineral content of up to 16% was achieved. “This underlines the enormous potential of our workflow.

“We are currently working on various case studies in the Follow-up project Cosilflot+, including the exchange of high-toxic hydrofluoric acid through sodium flotation and the implementation of biopolymers to separate chalcopyrite and molybdenit,” said Ben.

The results offer mining companies and manufacturers of flotation reagents a good usage possibility, since companies can react better to changes in complex mineral compositions. The flexibility is also advantageous for the implementation of environmentally friendly flotation reagents, since the mining industry depends on ecologically compatible reagents in the future. In addition, the workflow offers good prospects of being proclaimed as a company.

“After a successful validation, we plan a spin-off that offers the Cosilflot+ Workflow as a technical service for mining companies and chemical manufacturers. The aim is to bring both players together to develop efficient and environmentally friendly solutions and to further optimize the process results.

“At the same time, manufacturers of flotation reagents can open up new applications for their products and thus improve their market opportunities,” says Ben.