Moisture- and ash-free

Component Moisture Volatile matter Fixed carbon Non- combustible As collected Dry Moisture-and ash-free... 

Chemistry. The moisture- and ash-free fixed carbon figures for this coal are relatively high (Table I). Most of the samples exceeded 80% fixed carbon, and all the samples exceeded 80% ultimate carbon. About one-third of the... 

Empirical parameter describing how the Donnan volume varies with ionic strength. Carboxyl group content (mmolg 1 on moisture- and ash-free basis). 

All data are reported on a moisture and ash-free basis. b The value of s is one standard deviation for four determinations. 

Table IV lists the moisture and ash-free sulfur values for the eight coals before and after they were physically cleaned to reduce the mineral matter. The moisture and dry ash values for the cleaned coals are also listed. One can see from the results of the cleaning that the sulfur contents of the eight coals were substantially reduced.

The ash content of raw and treated coals is reported on a moisture-free basis and the sulfur content on both a moisture- and ash-free basis. The ash reduction achieved corresponds to the overall change in moisture-free ash content divided by the moisture-free ash content of the raw coal. The reduction in total sulfur content corresponds to the change in total sulfur content divided by the total sulfur content of the raw coal, all on a moisture- and ash-free basis. The apparent reduction in organic sulfur content corresponds to the difference between the sulfur content of the acid-leached raw coal and the final sulfur content of the acid-leached, alkali-treated coal divided by the sulfur content of the acid-leached raw coal, all on a moisture- and ash-free basis. Coal recovery corresponds to the mass ratio of coal recovered during the alkaline treatment step to coal charged, all on a moisture- and ash-free basis. 

Several bituninous coals have been treated with molten mixtures of NaOH plus KOH at 350-370 C in a 1 10 coal-to-caustic ratio for 1 hour and then washed with water, dilute acid, and finally with water again. By this procedure, which is similar to that of the TRW Gravi-melt Process, 80-90% of the ash and 70-80% of the total sulfur have been removed with a recovery of 80-90% of the coal on a moisture- and ash-free basis. The desulfurization could be improved by using a finer grind of coal, better washing procedures, or a recleaning step. 

Standard Conditions. The results for several cleaning experiments on the Pittsburgh No. 8 (PT8) and Illinois No. 6 (IL6 or IL6A) coals are presented in Table II. For the Pittsburgh coal cleaned under standard conditions (runs 3 and 16), 77-82% ash removal and 65-72% sulfur removal were achieved with recoveries around 85-90%. For the Illinois coal, (IL6 6, IL6A 1, and IL6A 2), the ash and sulfur removal was better at 87-89% and 72-78%, respectively, while recovery was lower at 75-79% on a moisture- and ash-free (MAF) basis. 

Coal treated at the Ames Laboratory with molten caustic by a procedure similar to that of the Gravimelt Process resulted generally in 80-90% reductions in ash and 70-80% reductions in total sulfur. The recoveries of coal on a moisture- and ash-free basis were 80-90%. 

The mg of galacturonic acid obtained in this way is the content of one-tenth of the weight of the washed and dried sample. To calculate the percent galacturonic acid on a moisture-and ash-free basis, multiply the number of mg obtained by 1000/x, in which x is the weight, in mg, of the washed and dried sample. If the pectin is known to be of the nonamidated type, only V and Vi need to be determined, and V3 may be regarded as zero in the formula for calculating mg of galacturonic acid. 

The determination of depolymerized coal in this filtrate was accomplished by diluting a weighed aliquot with 20-30 times its weight of water. Phenol and catalyst dissolve whereas the depolymerized coal product precipitates. The precipitate was filtered, water washed, and dried in a vacuum at 110 C. The weight of this precipitated product was designated as maf (moisture and ash free) depolymerized product. 

When Monarch (Lower Bench) coal (W-74-53) was hydrotreated with synthesis gas In anthracene oil and 25 wt% moisture at 425 + 5°C, an operating pressure of 3900-4000 psl, and a reaction time of one hour, a 99% conversion and 727. selectivity to oil on a moisture- and ash-free basis was observed. The viscosity of the coal oil in anthracene solvent was remarkably low, 53 cen-tlpolses at 60°C. At lower residence time from 15 min. to 30 min., the product oil resulted In a high viscosity, even-though the conversions were not greatly affected. These data are shown in Table III and Figure 1. 

Essentially all the subbltumlnous coals when hydrogreated with synthesis gas In anthracene oil and adequate amounts of moisture resulted In high conversions varying from 90 to 99% on moisture- and ash-free basis at a temperature of 425 + 5°C, an operating pressure of 3500 to 4500 pslg, and a residence time of an hour. The product oil Invariably had a low viscosity. 

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