Flotation and magnetic separation processes for a mineral of wollastonite

This paper presents the results of laboratory processing tests conducted to explore the potential for beneficiation of a wollastonite mineral (calcium metasilicate, CaSiO3). The ore studied comes from a mineralized body located in the southern part of Sardinia (Italy), which has been studied in the past with geological surveys and sampling. In the investigated area the mineralization was very irregular. The encasing rocks consist of schist and the mineralized body is composed of wollastonite associated with limestone, garnets and silica. The sample used for treatment tests was taken from this area and underwent various tests, including grinding, froth flotation, and magnetic separation. Finally, we conducted an overall treatment test using the beneficiation techniques that yielded the best results in the previous experiments. The treatment scheme followed in the overall test utilized simple techniques such as grinding, calcite flotation and magnetic separation. As a result, the concentrate contained 80% wollastonite and met the pollutant element specifications. The final grinding stage was necessary to meet the market's required particle size specifications. The flotation tests were conducted in a Denver laboratory cell, while a Jones wet high-intensity magnetic laboratory scale separator was used for the magnetic separation tests. The effectiveness of the various steps of testing was verified by comparing the results obtained with the specifications required by the wollastonite market, which impose minimum quantities of contaminants, such as iron, titanium and magnesium, while being less severe with regard to SiO2 and CaO contents.