Separation and utilization studies of bitumens from bituminous sandstones of the Vernal and Sunnyside, Utah, deposits

In the search for possible future sources of petroleum products, the recovery and utilization of bitumens from the large outcropping deposits of bituminous sandstones in the United States have been under study by the Bureau of Mines for the past several years. The results of laboratory research in the adaptation of the hot-wator separation process to recovery of bitumen from bituminous sandstones were reported in an earlier publication on the Edna deposits near San Luis Obispo, Calif. This publication included analytical data on the cracked products and asphalts obtained from the extracted bitumen and on the cracking and distillation of the bitumen. Comparable hot-water separation tests have been run in the San Francisco, CA, laboratory of the Bureau of Mines on quarry samples from the large deposits of bituminous sandstones near Vernal and Sunnysido, Utah. The bitumens were isolated from the extracts of the separation plant and analyzed at the Petroleum, and Oil-Shale Experiment Station of the Bureau of Mines, Laramie, WY. Part I of this report summarizes the general characteristics of the Vernal and Sunnyside deposits and discusses the hot-water separation process as applied to those bituminous sandstones and the results obtained. The separation tests showed that these bituminous sandstones also respond to treatment by the hot-water method of separation. The bitumen in the Vernal sandstone was extracted more readily by the action of hot water than was the Edna bitumen, which greatly simplified plant operation. The Vernal sandstone contains no water-soluble iron compounds, such as were found in the Edna sandstone, and, therefore, required no preliminary water washing. Recovery of bitumen from the Vernal sandstone was about 96 percent. In contrast to the softness of Edna and Vernal sandstones, the Sunnyside sandstone is an extremely hard asphalt rock that must be crushed to small size to facilitate complete disintegration and displacement of the bitumen from the the sand grains in pulping. The disintegrated sand was fine and contained a high percentage of silt, which increased the loss of bitumen to the tailings discharged from the plant. About 90 percent of the original bitumen in the Sunnyside sandstone was recovered. In part II of the report, analytical data are presented, which indicate possible uses for the products. The unaltered bitumens, after recovery, were analyzed by the Bureau of Mines routine method for crude oils. They contained very little paraffin wax and sulfur, but considerable amounts of nitrogen were present. The unusually low sulfur content is a very desirable characteristic if liquid fuels are to be prepared. At reduced pressure, extremely viscous oils with low wax content can be distilled from the materials, indicating that they may contain suitable stock for preparing special purpose lubricants. Tho bitumens were investigated as possible sources of asphalt. Two straight-run asphalts from each of tho two extracts were prepared having penetrations ranging from 48 to 165 decimillimeters at 77° F. Properties of the four asphalts were determined by commonly accepted asphalt -tests and are presented in this report in tabular form. Values of these properties for a 100- penetration asphalt from each of the bitumens were estimated from graphs obtained by plotting the experimental data. An indication of the suitability of these asphalts for commercial applications is shown by comparing the estimated properties of their 100-penetration asphalts with those of certain petroleum asphalts. In some respects the Utah asphalts resembled those from Oregon Basin, WY, and Tampico, Mexico, crude oils, although the sulfur content was much less. Portions of the bitumens were cracked by destructive distillation to demonstrate the feasibility of producing motor fuels from the resulting coker distillates. The fuels were satisfactory in most respects but had a strong tendency toward gum formation. Although distillate burner fuels were not actually prepared, the properties of the motor fuels show that various grades of burner oil can be produced by the same process that produced the motor fuels. Although other products, including lubricants and wax, were formed by cracking, a detailed study of them was not made.