The fluorspar is the favorite material for the reduction of clinkering temperature. The addition of 0.5% or 0.75% fluorspar to the raw mixture was reported by L. Erdmenger, O. V. Blease and A. W. Robertson. Then, the author has made following study to find the suitable content of the fluorspar in the high silica and lime raw mixture which is difficult to burn.
As preliminary experiments, 0.0%, 0.5%, 2.0%, 4.0%, 6.0% or 8.0% fluorspar were added to a raw mixture. These raw mixtures were burnt in a small rotary kiln (40×55×700cm.) with heavy oil.
Results are: (1) That containing 0.0%, 0.5% or 2.0% fluorspar gave common clinker and cement. (2) That containing 4.0%, 6.0% or 8.0% fluorspar melted in the kiln and did not gave common clinker. (3) The content of the fluorspar is not necessary to exceed 2.0%. (4) Setting time of the cement was retarded by the addition of fluorspar to the raw mixture.
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