Asphalt coking value

Other test methods that are used for determining the coking value of tar and pitch (ASTM D-2416, ASTM D-4715), which indicates the relative coke-forming properties of tars and pitches, might also be applied to asphalt. Both test methods are applicable to tar and pitch with an ash content <0.5% (ASTM D-2415). The former test method (ASTM D-2416) gives results close to those obtained by the Conradson carbon residue test (ASTM D-189, IP 13). However, in the latter test method (ASTM D-4715), a sample is heated for a specified time at 550 10°C (1022 18°F) in an electric furnace. The percentage of residue is reported as the coking value. 

The residua from which asphalt are produced, once considered the garbage of a refinery, have little value and little use other than as a road oil. In fact, the development of delayed coking (once the so-called refinery garbage can ) was with the purpose of converting residua to liquids (valuable products) and coke (fuel). 

The deasphalting process is also based on carbon removal [4]. However, it uses a completely different technology. Here, asphaltenes are extracted by solvents from the heavy ends. Light hydrocarbon (e.g. propane) or supercritical gases are used as solvents. The resulting deasphalted oil is essentially free of metallic contaminants. The carbon removal processes yield large amounts of low-value coke or asphalt beside the desired hydrocarbon products. 

Gasification is a flexible, conunercially proven, and efficient technology for producing high-value products from lower value feedstocks. It can convert any solid or semisolid carbonaceous material (intermediate refinery streams, asphalt, petroleum coke, and refinery sludges) to synthesis gas. Almost 100% carbon conversion can be achieved and no solid by-product is left for disposal (Furimsky, 1999). 

---