Comparison of the Effects of Aspergillus niger and Aspergillus ficuum on the Removal of Impurities in Feldspar by Bio-beneficiation.

Depending on its purity, feldspar has a wide application in industry. Fungi play an important role in the feldspar purification. A bacterial leaching study of feldspar sample from Aydin, Turkey, was conducted to obtain a suitable raw material for industrial applications. XRD analyses indicated that albite (NaAlSi ₃ O ₈ ) with minor amounts of orthoclase (KAlSi ₃ O ₈ ), quartz (SiO ₂ ), muscovite (KAl ₂ (Si ₃ AlO ₁₀ )(OH) ₂ ), rutile (TiO ₂ ), and small quantities of weathered clay minerals. This study evaluates bacterial leaching treatment to iron removal from feldspar using Aspergillus niger and Aspergillus ficuum to attain a product suitable for industrial uses. These funguses were tested for organic acid (oxalic and citric acid) production and leaching capabilities of feldspar. The leaching performances of two funguses were compared. Bacterial leaching experiments were performed in 500-mL Erlenmeyer flask at 30 ± 2 °C and 180 rpm agitation under aseptic conditions. In bacterial leaching experiments using A. niger and A. ficuum, 70.13% and 85.09% of the total iron oxides in the feldspar were removed, respectively. As a result, the final iron oxide concentrations in bacterial leaching experiments using A. niger and A. ficuum were 0.095% and 0.047%, respectively (at 5% w/v pulp density, temperature 30 ± 2 °C, A. niger 3 × 10 ⁷ spores, A. ficuum 5 × 10 ⁷ spores, and particle size < 63 μm). The use of fungi to remove iron from feldspar has the potential to be an effective method for upgrading the content and the commercial value of the feldspar. The experimental results of this study have provided significant opportunity to use biotechnological approach for producing the feldspar as a feed material for the high-quality ceramic industry.