Problem statement

Problem statement[Total of 20 points + 2 bonus points]Having discovered a precious ore on the islands of St. Lucia called ROYGBIV, my friend and I decided to mine it and sell it for big money so we can retire early. Having flunked the unit operations course in our university days, we decide to hand the design problem over to you. There are two main issues we need you to untangle for us.

(A) Transporting the mined ore to the roaster

(10 points)

Figure 1: Rough layout of the mining/transport section of the plantFrom Figure 1, it is clear we want to use a recently discovered gas Laughing gas for transporting the oreFind out what should be the minimum velocity of the laughing gas to transport the ore without accumulation in the pipe. The average particle volume fraction is 0.3%.

State all necessary assumptions.

Magnetite (Specific gravity of 0.5, particle size range of 50m to 300m). Nitrous oxide gas (Specific gravity of 1.53, kinematic viscosity of 1.36x10-5kg/ms). (B)Specifying a fluidized bed roaster (FBR)(10 points)Using your answers in (A), we need you to determine some steady-state characteristics of the FBR. Apparently, a variant of the transport gas used in (A) and with similar properties, Laughing gas2 has some cleaning properties with which we can clean our dirty ore with.

Bonus question 1 (2 points)Where do you think the authors got the inspiration for naming the ore ROYGBIV and what does it mean?

Bonus question 2 (1 point)For a bonus of 1 point, take a wild stab in the dark and guess what is the authors favourite cartoon character.

You may find the following information useful.Laughing gas properties:Density (kg/m3) = 3.45Dynamic viscosity (kg/m.s) = 2.5 x 10-5ROYGBIV ore properties (mean):

Density (kg/m3) = 3200Diameter (microns) = 100

Transport pipe:Diameter (m) = 200 mm

Length (m) = 500 mFBR:Diameter (m) = 5 mEquation SheetYou may find the following equations to be useful.EquationSuggested limitation

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Conveyor belt

Transport pipe

Storage

hopper

Laughing gas

Ore to roaster

Compressor

Crushed ore

ROYGBIV

Control valve

Fluidized ore roaster

Hw

Refined ore ROYGBIV

Overflow

weir

Gas distributor

Dirty gas

Laughing gas2

Raw ore ROYGBIV

(from storage hopper)

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