Crude iron-rich bentonites were investigated by metallic element analysis. The bentonite samples were grinded and sieved to obtained micro-particles with the size lower than 160 Mesh, then acidification was carried out in order to remove metallic (mainly Fe) impurities. During treatment, the influences of the sort and concentration of acid, acidified time, calcination temperature on decoloring capability were discussed. By means of washing by water, filtering, drying and calcinating, acidified products were obtained, and then tested the whiteness of the product after calcination. In the decoloring experiments, the optimum conditions were obtain as follows: the concentration of nitric acid is 8 mol/L, acidified times 16 h, calcination temperature 550 ℃, calcination times 2 h.Under these conditions, the color of the samples is transformed from brown-red to milky white. The samples whiteness changes from 43.0 to 81.6.

The extrusion moulding experiments on the bleaching bentonite was carried out to make the extrusion easy and improve the products' mechanical strength. Influences of amounts of water and the additive on extrusion and mechanical strength were studied. It was indicated that the optimum amounts of water, in per 100 g bentonite, moulding lubricant and cementing material are 60 mL, 5 mL, and 2.5 g respectively. The strength of bentonite is increased from 45 N/cm2 to 112 N/cm2 after acid treatment.