Glass- and ceramic-grade feldspar from waste

In a typical feldspar operation extraction and size reduction may account for 20 to 25% of operating costs. Production of feldspar from feldspathic quarry fines and / or mine tailings would avoid this cost as the material has already been extracted and crushed. Other benefits arise from a reduction in waste treatment and disposal, an increase in the revenue realised per tonne of material extracted and, ultimately, an environmental benefit from a reduction in feldspar mined. Feldspathic waste materials in the form of granite fines from an aggregate quarry in Scotland and tailings from a former tin mine in Namibia were examined. Samples were processed on a laboratory-scale as an initial investigation into the feasibility of producing glass- and ceramic-grade feldspar products. A combination of magnetic separation and a two-stage froth flotation was used to remove iron-bearing minerals, mica and to separate quartz from feldspar. An HF-free froth flotation process was used for the latter. High-purity feldspar was produced with Fe2O3 and alkali contents similar to those of commercial feldspar. High-purity quartz was also produced as a by-product.on the basis of these laboratory results, the potential for scalingup the processing of fedlsapthic waste to a commercial scale would appear to be a viable prospect.