since the structure of the material is all carbon ,we can use the ASTM D3172 test which is described for Coke and Coal then For testing Gilsonite Ash, we use this test.
This test method covers the determination of the inorganic residue as ash in the analysis sample of coal or coke as prepared in accordance with Method D 2013 or Practice D 346.The results obtained can be applied as the ash in the proximate analysis, Practice D 3172, and in the ultimate analysis, Practice D 3176. For the determination of the constituents in ash, reference is made to Test Methods D 2795 and D 3682. See Terminology D 121 for definition of ash.
Ash is determined by weighing the residue remaining after burning the coal or coke under rigidly controlled conditions of sample weight, temperature, time, atmosphere, and equipment specifications.
Place a preignited capsule with 1 g of sand at the center of the working area of the furnace, and by the use of a
potentiometer and thermocouple or other suitable temperature measuring device, measure the temperature of the sand in the crucible. The crucible and sand should be at temperature equilibrium with the furnace. There should be two to four air changes per minute moving throughout the furnace (the air flow may be measured by using a wet-test meter or equivalent calibrated at standard conditions for air connected to the ceramic-pipe exhaust). Adjust the furnace temperature until the potentiometer reads 750 6 10°C and then adjust or read the temperature on the indicating pyrometer. Use this reading as the proper setting for controlling the furnace.
The sample shall be the material pulverized to pass No.60 (250-mm) sieve in accordance with Method D 2013 or Practice D 346.
Transfer approximately 1 g (weighed to the nearest 0.1mg) of the thoroughly mixed sample to a weighed capsule and cover quickly. An alternative way is to use the dried coal from the moisture determination in Test Method D 3173. After removing the covers, place the capsule containing the sample in a cold furnace and heat gradually at such a rate that the temperature reaches 450 to 500°C in 1 h.
Heat coal samples so that a final temperature of 700 to 750°C is reached by the end of the second hour. Heat coke samples so that a final temperature of 950°C is reached by the end of the second hour. Continue to heat at the final temperature for additional 2 h. remove the capsule from the muffle, place the cover on the capsule, cool under conditions to minimize moisture pickup, and weigh.
Calculate the ash percent in the analysis sample as follows:
Ash in analysis sample, % = [(A-B)/C] × 100
A = weight of capsule, cover, and ash residue, g,
B = weight of empty capsule and cover, g, and
C = weight of analysis sample used, g.