A series of multiple-effect evaporators is to be used for evaporating 400,000 kg water per day from a salt solution. The total initial cost for the first effect is $18,000 and each additional effect costs $15,000. The life period of the evaporators is estimated to be 10 years and salvage or scrap value at the end of life period is assumed to be zero. A straight-line depreciation method is used in the optimization analysis. Fixed charges are 15% yearly based on the first cost of equipment. Steam costs $1.50/100 kg. Annual maintenance charges are 5% of the initial equipment cost. All other costs are independent on the number of effects. The series will be operated 300 days per year. If steam company is related to the number of effects as =0.85 N, where N is the V. number of effects. Determine the optimum number of effects for minimum annual cost.

3 during a wet milling, %50 of mill volume is filled by balls,30% of the mill volume is filled by the slurry. you are asked to prepare a mill charge for a 10 m^3 ball mill by using alumina balls of 4 cm size. calculate the amount of ball, raw material and water to be added to the mill Assumptions:Alumina ball's packing density 60% volume,slurry density:1650 gr/lt slurry solid content:65 weight %

please answer number 09 please

An ore having 80% passing 10 mm is fed to a mill with a capacity of 12 t/h. The ground product has 80% passing o,9 mm. It is required to grind 80% of the ore to a size of below o,4 mm and to keep the same amount of energy required. Calculate the amount of ore that can be fed to the mill per hour to achieve this requirement