Gypsum processing pellets made from magnetite - 1 views

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  #1 betsy stone on 15 Aug 14

   

  It has been found desirable in producing hardened pellets of magnetic taconite concentrates to apportion the fuel added to the pellets, in the form of coke breeze, to about 1.2% by weight of the dry ore, the actual quantity of admixed fixed carbon being only 1.08% of the dry weight of the ore. With this small quantity of fuel supplying 60-70% of the total heat requirement, the other 30-40% being supplied by the heating and ignition flame,gypsum processing pellets made from magnetite, sufliciently hard to withstand the necessary transportation and the impacts and pressures incident to handling in the blast furnace and open hearth processes, are produced with a total heat consumption in the neighborhood of only about 500,000 B. t. u. per long ton of ore.
  
  Example.-The process has been carried out with finely divided magnetic taconite concentrates pelletized with 1.3% admixed coke (about 1.14% fixed carbon) in a twenty inch layer of which eighteen inches were green pellets and two inches grate protection. The average pellet size was five-eighths inches;coal washing process diagram drying time was ten minutes with drying gases at a temperature of 500 F.- 550 F. Ignition time was three and one-half minutes; flame temperature as indicated by an ordinary thermocouple in the flame was 2250 F. After ignition, cold air was drawn down through the layer for twenty-nine minutes. The temperature peak in the lowest green pellets was reached twelve minutes before discharge from the grate. The hot air from below the grate during the last twelve minutes averaged 850 F. and was usable as heated air in the drying and ignition steps.
  
  The process and apparatus described can be simplified by omitting the predrying and heat recuperation. For instance, it is feasible to shorten the time of operation or treatment on the grate by igniting the undried pellets with a flame produced by burning fuel with cold air. The pellets crack or disintegrate to some extent and more fines are found in the product. As soon as the heat wave has passed to the bottom of the layer the pellets can be discharged without cooling partly in white hot state. By using this simplified method of burning pellets the quality of pellets is lowered due to presence of fines and the heat consumption is increased considerably. By omitting the predrying, cooling and heat recuperation from the grate, the same grate area can produce up to twice as many pellets and the capital cost is lowered correspondingly. The heat economy and quality of pellets has to be balanced against the capital cost under each particular condition.

   

  <div class="cArrow"> </div><div class="cContentInner">It has been found desirable in producing hardened pellets of magnetic taconite concentrates to apportion the fuel added to the pellets, in the form of coke breeze, to about 1.2% by weight of the dry ore, the actual quantity of admixed fixed carbon being only 1.08% of the dry weight of the ore. With this small quantity of fuel supplying 60-70% of the total heat requirement, the other 30-40% being supplied by the heating and ignition flame,<a rel="nofollow" href="http://www.sellercrusher.com/solutions/gypsum-processing.html">gypsum processing</a> pellets made from magnetite, sufliciently hard to withstand the necessary transportation and the impacts and pressures incident to handling in the blast furnace and open hearth processes, are produced with a total heat consumption in the neighborhood of only about 500,000 B. t. u. per long ton of ore. <br /> <br /> Example.-The process has been carried out with finely divided magnetic taconite concentrates pelletized with 1.3% admixed coke (about 1.14% fixed carbon) in a twenty inch layer of which eighteen inches were green pellets and two inches grate protection. The average pellet size was five-eighths inches;<a rel="nofollow" href="http://www.sellercrusher.com/solutions/coal-washing-process-diagram.html">coal washing process diagram</a> drying time was ten minutes with drying gases at a temperature of 500 F.- 550 F. Ignition time was three and one-half minutes; flame temperature as indicated by an ordinary thermocouple in the flame was 2250 F. After ignition, cold air was drawn down through the layer for twenty-nine minutes. The temperature peak in the lowest green pellets was reached twelve minutes before discharge from the grate. The hot air from below the grate during the last twelve minutes averaged 850 F. and was usable as heated air in the drying and ignition steps. <br /> <br /> The process and apparatus described can be simplified by omitting the predrying and heat recuperation. For instance, it is feasible to shorten the time of operation or treatment on the grate by igniting the undried pellets with a flame produced by burning fuel with cold air. The pellets crack or disintegrate to some extent and more fines are found in the product. As soon as the heat wave has passed to the bottom of the layer the pellets can be discharged without cooling partly in white hot state. By using this simplified method of burning pellets the quality of pellets is lowered due to presence of fines and the heat consumption is increased considerably. By omitting the predrying, cooling and heat recuperation from the grate, the same grate area can produce up to twice as many pellets and the capital cost is lowered correspondingly. The heat economy and quality of pellets has to be balanced against the capital cost under each particular condition.</div>

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