Task 4.0 -- Advanced fuel forms and co-products. Semi-Annual report, April 1--June 30, 1993

Abstract

Summarizedbelowisthework carried outoverthesix-month period, JulyI toJune 30,1993,on thesubtasks Beneficiation forAdvancedSystems, Co-Products, and Low-Rank CoalLiquefaction. Beneficiation forAdvancedSystemsconsists oftwo parts:Dust Generation and OilAgglomeration. • BENEFICIATION FOR ADVANCED SYSTEMS A. Dust Generation Hydrothermaldrying (hot-water dryingand saturated-steam drying) was determined tobe an effective method ofcausinga permanentreduction intheequilibrium moisture of low-rank coals and removingsodium.Moisture reduction forthreetest coals varied from 56 to86 wt%, whilesodiumreduction was as highas 75%. Variousstability tests were conducted on raw and hydrothermally treated coals todetermine the effect ofdrying on thefriability ofthelump coal.The results indicated thatasmoisture was reduced, the amount offugitive dustand fines generation inc,'eased substantially. An additional task oftheprogramwas todevelop stability tests basedon American Society forTesting and Materials (ASTM) procedures whichcouldaccommodatea smaller coalsize and reduced amount ofcoal.The development ofimprovedmethodsiscontinuing forassessing the propensity ofcoals todustgeneration. B. Oil Agglomeratior. Carbonicacidtreatment oflignites and subbituminous coals reducedthesodium contents ofthesecoals by 60 to70 wt%. Float/sink washability testing oflow-sulfur subbituminous coals produced ash reductions of30 to40 wt% at+95 wt% moisture and ash-free (mar)coal recovery, indicating their potential forbeneficiation by selective agglomeration. Lignites and subbituminous coals were successfully agglomerated without prior chemical treatment of the coal surface or without adjusting the pH of the water. Selective agglomeration of a low-sulfur Powder River Basin (PRB) subbituminous coal produced ash reductions of 35 wt% with maf coal recoveries over 85 wt%. Agglomerates with higher ash content than average for PRB coals from selective agglomeration were successfully enlarged with additional coal-derived oil. Ineffective agglomerants were induced to agglomerate low-rank coals by mixing with a polar oil or polar alcohol. Effective agglomeration promoters were crude phenol, m-cresol, cresylic acid, methanol, ethanol, propanol, and butanol. Preliminary results show the potential for enhancing agglomerate integrity using a partially polymerized coal gasification-derived oil as a binder. Air-dried agglomerates containing presumably polymerized oil were appreciably resistant to degradation and generation of nuisance dust. Thermal deoiling of these agglomerates yielded a product with reduced strength. ES-1 @ CO-PRODUCTS .. Threecoals, a NorthDakota Lignite, a NorthDakotaLeonardite, and an Alaskan subbituminous coal, were pyrolyzed under nitrogen at a temperature of 850°C and ambient pressure using rapid and slow heatup and staged heating programs. The resultant chars were activated with and without steam. Proximate analysis showed that the subbituminous char collected from the reactor was typically lower in volatiles than the lignite. Lower recoveries o...