A copper concentrate of the following composition (weight %); Cu- 8.8%, SiO2-19%, Fe - 29.7%, S-36.9%,...

 

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A copper concentrate of the following composition (weight %); Cu- 8.8%, SiO2-19%, Fe - 29.7%, S-36.9%, Al2O3 - 5.3%, CaO - 0.3% is roasted in a fluidized-bed roaster to give a roasted ore of the following composition; Cu - 11.1%, SiO2 -24%, Fe - 37.6%, S-10%, Al2O3 - 6.7%, CaO -0.4%, O2-10.2%. Copper in the roasted ore is present as CuS, Iron in the roasted ore is present as FeS, Fe2O3 and Fe3O4. During roasting 5000 m (STP) of air is used per tonne of concentrate and the fuel rate is 5kg of carbon per tonne of concentrate. Of the sulphur that is oxidized 85% reacts to produce SO2 and 15% reacts to produce SO3. Using a basis of 1000kg of concentrate, calculate; (i) Weight of the roasted ore. (ii) Weight of Cu2S, FeS, Fe2O3 and Fe3O4 in the roasted ore. (iii) Percentage composition of flue gases. (v) Percentage excess air used for combustion and roasting. [2] [10] [6] [2] A copper concentrate of the following composition (weight %); Cu- 8.8%, SiO2-19%, Fe - 29.7%, S-36.9%, Al2O3 - 5.3%, CaO - 0.3% is roasted in a fluidized-bed roaster to give a roasted ore of the following composition; Cu - 11.1%, SiO2 -24%, Fe - 37.6%, S-10%, Al2O3 - 6.7%, CaO -0.4%, O2-10.2%. Copper in the roasted ore is present as CuS, Iron in the roasted ore is present as FeS, Fe2O3 and Fe3O4. During roasting 5000 m (STP) of air is used per tonne of concentrate and the fuel rate is 5kg of carbon per tonne of concentrate. Of the sulphur that is oxidized 85% reacts to produce SO2 and 15% reacts to produce SO3. Using a basis of 1000kg of concentrate, calculate; (i) Weight of the roasted ore. (ii) Weight of Cu2S, FeS, Fe2O3 and Fe3O4 in the roasted ore. (iii) Percentage composition of flue gases. (v) Percentage excess air used for combustion and roasting. [2] [10] [6] [2]