Problem 2: Material balance in roasting of lead concentrate

The lead concentrate of a particular plant analyzes and remaining . The concentrate is treated by roast-reaction method to produce Pb. The reactions during roasting stage are:







At the end roasting stage all  is oxidized, but some  remains. The formation of and  is in the ratio 1:3 by weight. During the reaction stage following reactions occur:





Both of the above reaction continues till all has been consumed.

Find:

a) Weight of the end of roasting stage and its proximate analysis/ 1000 kg concentrate.

b)% S eliminated at the end of roasting stage.

c) Gases formed  during (i) roasting stage (ii) reaction stage in  at 1atm and 273K

Solution:

Proximate analysis of ore refers to mineral analysis.

Roasted ore contains We can easily calculate amounts of  and

 Let x kg  forms in roasting stage

Let y kg PbS left at the end of roasting stage

Perform material balance of lead in roasting stage and reaction stage



Weight of ore

and

% S eliminated

Gases formed  roasting stage and 3 in reaction stage