We are now in sight of the real 'concentrates,' which are conveyed to dryer No. 弗兰克·刘易斯·戴尔.爱迪生的生平和发明.
Obviously, at each step the percentage of felspar and phosphorus is less and less until in the final concentrates the percentage of iron oxide is 91 to 93 per cent. 弗兰克·刘易斯·戴尔.爱迪生的生平和发明.