Abstract:A process for biological removal of iron from quartz sands, kaolins and clays was developed in which these industrial minerals were leached at 90°C with lixiviant produced as a result of the cultivation of acid-producing heterotrophic microorganisms, mainly strains of Aspergillus niger, a t 30°C in a nutrient mediom containing molasses as a source of carbon and energy. The lixiviant.i.e. the fermentation fluid, contained oxalic and citric acids as main components and after the cultivation was acidified to n pH… Show more
“…Welch and Ullman (1993) found that the rate of plagioclase dissolution in solutions containing organic acids was more compared to inorganic acids and further showed that polysaccharides produced by the bacterium during the process of reproduction can combine with the minerals to form bacterial mineral complexes which leads to degradation of the minerals. Groudev (1987) reported that production of slime or acidic exopolysaccharides (EPS) contributed to the mechanism of releasing potassium from silicates. Liu et al (2006) demonstrated that polysaccharides strongly adsorbed the organic acids and attached to the surface of the mineral, resulting in an area of high concentration of organic acids near the mineral.…”
“…Welch and Ullman (1993) found that the rate of plagioclase dissolution in solutions containing organic acids was more compared to inorganic acids and further showed that polysaccharides produced by the bacterium during the process of reproduction can combine with the minerals to form bacterial mineral complexes which leads to degradation of the minerals. Groudev (1987) reported that production of slime or acidic exopolysaccharides (EPS) contributed to the mechanism of releasing potassium from silicates. Liu et al (2006) demonstrated that polysaccharides strongly adsorbed the organic acids and attached to the surface of the mineral, resulting in an area of high concentration of organic acids near the mineral.…”
“…Production of capsular polysaccharides along with organic acid production like tartaric and oxalic acid by the microorganisms leads to solubilization of feldspar and illite to release K (Sheng and He 2006). Another report showed that K was solubilized by release of inorganic and organic acids and due to production of mucilaginous capsules containing of exopolysaccharides by Bacillus, Clostridium and Thiobacillus (Groudev 1987). The weathering ability of the bacteria involves production of protons, organic acids, siderophores and organic ligands, which act as chelating agents and do the process of chelation by making the K mineral free for crop uptake.…”
“…In a study it was reported that potassium soluiblizing bacteria B. mucilaginosus are able to soluiblize rock K mineral powder such as micas, illite and orthoclases through production and excretion of organic acids (Ullaman, 1996). Another report showed that potassium was soluiblized by production of inorganic and organic acids and due to production of mucilaginous capsules containing of exopolysaccharides by Bacillus, Clostridium and Thiobacillus (Groudev, 1987).…”
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