An ore containing 5% of lead is fed to a bank of flotation cells. High grade concentrate is produced from the first circuit (Circuit 1) assaying 52% of lead while the tailing from this circuit assay 0.7% lead. The tailings feeds a lower grade circuit (Circuit 2) that produce a contrite grading 8% lead and a tailing that contain 0.2% lead. Calculate the weights of high and low grade concentrates and the recovery of lead to concentrates. The feed tonnage to circuit 1 is 28t/h.

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?

Different types of steels contain different elements that alter the characteristics of the steel. for each of the following elements, explain what the element does when alloyed with steel.

Water at 55c flows across a flat plate whose surface temperature is held constant at 95c. if the temperature gradient at the plate's surface for a given value of x is 18 c/mm, find a) local heat transfer coefficient. b) heat flux