Optimisation of physical factors for bioleaching of silica and iron from bauxite ore by a mutant strain of Aspergillus niger

摘要

In mutation of Aspergillus niger strain AB with ethylene imine (1: 5000) and X-rays a mutant strain A. niger X_1 is obtained. Bioleaching of silica and Iron from bauxite ore is performed with that strain and a greater amount of leaching of silica (39.87 per cent) and iron (46.4 per cent) as against the parent strain (9.8 and 10.1 per cent respectively) is observed by surface culture method of fermentation. The effects of particle size, pulp densities, volume of medium in 250 ml flask, initial pH, temperature, inoculum volume and age of inoculum are also studied. It has been found that optimum particle size-170 to 200 mesh, pulp densities beyond 0.3 per cent inhibited silica and iron release, optimum volume 80 ml, initial pH of the medium 4.0, optimum time period of fermentation is 7 days, inoculum volume 6 per cent and optimum age of inoculum 7 days. The maximum leaching of silica and iron by using these optimum physical factors are 56.2 and 59.5 per cent respectively.