EQUIPMENT DESIGN:

1). Ball Mill: Feed Rate = 218 ton/hr

= 218000 kg/day

= 9083.333 kg/hr

Feed Tons/hr Fraction DensityKg/m3

Average DensityKg/m3

Rock 8992.50 99% 2740 2712.6Water 90.83 1% 1000 10 Sav = 2722.6 kg/m3

Volumetric Flow rate = 9083.333 kg/hr * m3/2722.6 kg

= 3.3363 m3/hr

Power Calculations:

P = 0.3162 Wi m (√1/Dp – √1/Df)

Df = feed size = 25.4 mm

Dp = product size = 0.08 mm

Wi = work index = 13.23 Kwh/ton

M = 9.0833 ton/hr

So,

P = 126.8 Kw

Efficiency = 70%

P = 181.14 Kw = 242.8 hp

Grinding Time:

Sx = E * 100 / Wi * Wt * 60 E = 242.8

Wi = 13.23 Kwh/ton

Wt = 9083.333 Kg/hr

So,

Sx = 0.0336

Time for grinding

1/Sx * ∫ Dxy/Xy = - ∫ dt

t = 60 minutes = 1 hr

Volume of Mill: Total feed rate = 3.33633 m3/hr

Grinding time = 1 hr

Volume of void space required = 3.33633 m3/hr

With material to grind Void space occupied by balls = 41%

Volume occupied by balls = 3.363/0.41 = 8.137 m3

As balls should occupy half of mill

Volume of ball mill = 8.137 * 2 = 16.275 m3

For closed loop grinding

L/D = 1

V = 3.14/4 * D2L = 3.14/4 D3

D = 2.75 = 8 ft.

Critical speed: N = 42.3/D1/2

= 25.5 RPM

Operating Speed:

No = 0.75 * 25.5 = 19.13 RPM

Maximum Diameter of Balls: B = √F/K * [S Wi/100CsD1/2] 1/3

B = Maximum size of balls

F = Feed size = 25400 micron meters

K = constant = 330

Cs = Fraction of critical speed = 0.75

D = Diameter of balls = 4 ft.

So, B = 4 inches.

Weight of Ball Mill:

Density of balls = 290 lb/ft3 = 4646 Kg/M3

Weight of balls = 290 * 3.14 (D2/2) * 2.75 * 0.41 = 3882.2 lb = 1764 kg

2). REACTOR:

Total mass flow rate entering the reactor = 508 tons/day = 21166.67 kg/hr

Total volume entering the reactor = 14.826 m3/hr

Residence time = 1 hr

Take 30% excess volume for safety

So, volume of reactor = 19 m3

Geometry of cylindrical shell:

H/D = 2

Volume = 3.14/4 * D2 * H

So, D = 2.295 m

H = 4.59 m

Thickness = PiDi/2JF – Pi + Cc Di = 2.295 * 103 mm

Pi = 1424.6 * 9.8 * 4.59 = 64085.18 N/m2 = 0.0640 N/mm2 Design pressure = 10% excess = 0.0794 N/mm2

f = 125 N/mm2

J = 1

Cc = corrosion allowance = 0.5 mm/yr

Ts = 10.65 mm = 11 mm

Geometry of Header: Proposed headers are flanged and standard dished torrispherical

t = 1/8 + ts = 0.546 inches

Sf = 3 inches

i.c.r = 3t = 1.638 inches

r = dish radius = shell radius = 89.505 inches

AB = I.D/2 – i.c.r = 89.505/2 – 1.638 = 46.39 inches

BC = r – i.c.r = 89.505 – 1.638 = 87.867 inches

b = r – (BC2 – AB2)0.5

= 89.505 – (87.867 2 – 146.39 2)0.5

b = 10.882 inches

So, height of header = OA = t + b + Sf = 0.546 + 10.882 + 3 = 14.43 inches. Maximum bolt spacing:

BS = 2d + ( 6 t/m + 0.5 )

m = gashet factor = 2.5

d = bolt diameter

= 1 inch

t = flange thickness = 3/4 inch

BS = 4.3 inch

No. of bolts = dish radius/maximum bolt spacing = 89.505/4.3 = 21 bolts

Geometry of impeller:

Inside diameter of tank = 2.295 m

Baffle width = 0.05 D = 0.1836 m

Diameter of impeller = D/3 = 0.765 m

off wall clearance = 0.02 D = 0.0459 m

off bottom clearance = 0.2d = 0.5355m

width of blade/ dia. Of impeller = 0.125 So,

Width of blade = 0.0956 m

Length of blade/dia. Of impeller = 0.25 So,

Length of blade = 0.19128 m

Angle of blade = 90°

Power calculation for agitator:

Nre = ρuD/μ

ρ = density = 1424.685 kg/m3

u = velocity = 1.667 rev/sec

D = diameter = 0.765 m

μ = viscosity = 0.006 kg/m.sec

Nre = 2.316467 * 105

Using table between power and Reynold’s number

Npr = 2.4

P = Npr n3 D5ρ = 4150 watt = 5.56 h.p = 6 h.p.

3). Storage Tank:

Mass of acid in tank = 1000 ton = 1000,000 kg

Density of acid = 1332 kg/m3

Volume of acid in tank = 750 m3

Take 10% overflow margin,

So, Total Volume = 750 m3 * 1.1 = 825 m3

Geometry of Tank:

Diameter of tank = D

Height of tank = H = D

V = π/4D2H

D = 11 m

H = 11 m Thickness of Shell:

Pi = ρgH = 1332 * 9.8 * 11 = 143589.6 N/m2

Thickness of Shell = ts =PiDi/2Jf – Pi + C

Pi = design pressure

Di = inside diameter of tank

C = corrosion allowance = 2mm

J = efficiency factor = 0.8

F = stress value = 85 N/m.m2

Ts = 14 mm

4). PUMP:

Mass flow rate = 290 ton/day = 12083.33 kg/hr

Density = 1198 kg/m3

μ = 0.006 kg/m.sec

Volume flow rate = 10.086 m3/hr

Z = 6 m

L = 50 m

η = 75%

Le/D = 32 (90 degree elbow)

No. of elbows = 4

No. of Valve = 1

Le/D = 300 for globe valve

Le/D = 7 for open gate valve

No. of valves = 1 Nre = ρuD/μ

q = uA

u = q/A

= 1.08 m/sec

So,

Nre = 831497.22 From friction factor chart,

f = 0.0059

Total Le for fittings, valves = 22.31 m Σ f = friction for pipes, fittings = 2fV2 (L + Le) / gc D = 33.l25 J/Kg

η Wo = 39.143

Wo = 97.86 J/Kg = 1490 J/Sec

Wo = 2 h.p

BHP = Q * H * /3960*