El medio ambiente en la minería

133 T. KIMURA & H. KUROKAWA Figure 4 shows the draft control system at Toyo smelter. Draft at the aeíd plant inlet can be also controlIed by both the damper openiog and rotating speed of tbe S02 blower to get a balaneed draft between the smelter and the aeíd plant. Usually, the draft at the aeíd plaot iolet is controlIed by the rotating speed of the S02 blower with a damper position of almost 100% opeo, except for the cooverter's changing time between blowing and nonblowing in order to reduce unnecessary pressure drops and eleetrical power comsumption. When a 1arge and quick motíon is needed, sueh as a stop and start of the converter blowing or a charge of the cold dope to the converter, the control mode is automatically shifted from rotating speed control to damper control by the process computer. Tbe inside pressures at the flash furnaee and converter as well as at the aeíd plant ¡nlet are successfulIy controlled, as shown in Figure 4. -s ._.._ ..._..._...._ ...._..._..._........................_.........................__._........._ ................ o ..._ ..............._..._...._...._ ..._..._..._....._.........._ ..._ ....._..._ .._.................._ ..._...- - ~'~~~~~~~~~~~~~~~~~~~~~~I -11 ......_ ...- ...._ ........- ..._ .........._ ..._...._ ..._ ...._...._ ..._ ..._ ..........- ........._ ....- ..•._ ......- .. ......... 2 0 f"I.ASH ruRNACE DRAFT 110 ...._........._ ..•- ..._ •..•.••...•_..._ •.._ ..._ .........._ ..._ ...- ................_ .•._ ................_ ..•_ ....- o ... _.-.,.,.-,..Á no"""" ~,~."" t·"",#--.4" ... -60 _....._..._ ..._ ...._...._ ..._... DRnFT <'IT THE: ACIO PI.......T IHLET.._ ..• .._ ..•......·......_ .. 1'1.,3 /HX 10 3 1.50 ...._. -..;::¡¡¡,::::;;..._ .... ,,~~~t:::::;t;.;; GAS VOLUHE AT THE ACID PLAHT 30 ...._ ..._ ....- ...._ ..._ ..._..........._ ..._ ..._ ..._ .........._ ..._ ..._ ...._....- ...- ..._ .........._ ..._ ... 15 o ..._..._...._ ...._._.........._.. ~.!!~.2.:.~~~Il;! .. ~.~~..!.~:~ .. ?!l.~._ ..._ ...._...._ ..._ ..._ ...... 10 SI :2 e 1 S 1 e :2 S2 e 1 ~ ~,----------~JlI~--~' __________ ~ Figure 4. Perfomance data ofthe fumace draft control and theS02 strengtb corresponding to the converter fumace operation.