in 27 0 28 0begin of setting h min 2 25 1 45end of setting h min 3 05 2 25soundness test passed passedflow in cm 20 0 20 1flexural strength kp cm sup 2 1 day 47 45 3 days 56 53 7 days 65 66 28 days 73 75compressive strength kp cm sup 2 1 day 186 203 3 days 278 288 7 days 356 364 28 days 479 488______________________________________ in a gas fired rotary kiln with a capacity of 660 t day provided with planetary coolers marl of the composition 25 7 ignition loss 28 4 sio 2 15 5 al 2 o 3 9 4 fe 2 o 3 and 43 1 cao and a particle size of 3 to 10 mm was charged into the part of the kiln adjacent the planetary coolers by means of a screw due to the conical shape of this part of the kiln the marl clinker raw material was conveyed to the inlet openings of the planetary coolers where it mixed with the hot clinker discharged from the kiln and entered the cooler together with the hot clinker by the transfer of heat from the hot portland cement clinker to the marl clinker raw material an essential lowering of the temperature in the cooler was achieved the amount.