In a mechanical coal-washing process, a portion of the inorganic sulfur and ash material in the mined coal can be removed. A feed stream to the process consists of 73% coal, 11% ash, 11% sulfur, and 5.0% water (to suppress dust). The clean coal side of the process consists of 88% coal, 6.0% sulfur, 3.0% ash, and 3.0% water. The refuse side consists of 32% sulfur, with the remainder being ash, coal, and water. If 80 metric tons per hour of clean coal is required, determine the feed rate required for the mined coal and the composition of the refuse material. Also determine the mass rate for the refuse stream (in metric tons per hour).

The y form of iron is known as: a) ferrite b) cementite c) perlite d) austenite

Air is to be cooled in the evaporator section of a refrigerator by passing it over a bank of 0.8-cm-outer-diameter and 0.4-m-long tubes inside which the refrigerant is evaporating at -20°c. air approaches the tube bank in the normal direction at 0°c and 1 atm with a mean velocity of 4 m/s. the tubes are arranged in-line with longitudinal and transverse pitches of sl- st 1.5 cm. there are 30 rows in the flow direction with 15 tubes in each row. determine (a) the refrigeration capacity of this system and (b) pressure drop across the tube bank. evaluate the air properties at an assumed mean temperature of -5°c and 1 atm. is this a good assumption?

Coiled springs ought to be very strong and stiff. si3n4 is a strong, stiff material. would you select this material for a spring? explain.