I study about hexavalent chromium and its source in portland cement production. Before I have studied about this and measured total chromium by ICP analysis method. Now I want to study portland cement samples for determination and quantification of soluble and insoluble hexavalent chromium and find the main source of this pollutant and if possible to control such effects.

Whether silicosis is a hazard of cement manufacturing depends on whether there is free silica in the raw materials. However, whether there is free silica or not workers should avoid breathing any dust into their lungs. Dust mask should be worn wherever there are high dust levels. There is no free silica in the cement final product.

Is silicosis a potential hazard in cement manufacturing? If so, what kind of protective measures should be taken?

The factor of 1.64 you refer to is the raw mix to clinker factor taking into consideration dust losses from the preheater. If you have very high dust losses then this factor might need to be higher. However to justify a factor of 1.90 the dust losses will need to be in the region of 30 per cent of the feed to the top of the preheater. If this is the case and your dust collector is not working the pollution must be terrible.