Marange Resources Water Supply System Design-Odzi to Concession Pipeline

ODZI RIVER TO MINE CONCESSION B PROCESS

WATERSUPPLY PUMPING AND PIPELINE DESIGN

AND CONSTRUCTION PROJECT

COMPILED BY:

Augustine Marume

Patrick Magwegwe

Jacqueline Madziva

July 2013

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EXECUTIVE SUMMARY

Marange Resources (Pvt) Ltd, is a wholly government of Zimbabwe owned entity through the

Zimbabwe Mining Development Corporation (ZMDC), mining and processing diamonds in

the Chiadzwa diamond field in Manicaland Province. The mine concessions are situated

20km from the processing plants, which are located close to the Odzi River for easy

accessibility of water which is a critical raw material for diamond processing. The current

low performance in production due to aging mobile equipment which is perennially on

breakdowns has necessitated the need to relocate the processing plants to the mine

concessions close to the ore bodies. This change in facilities set-up requires that, water being

a critical resource in diamond processing must be continuously available for the plants to

operate consistently and sustainably with minimum stoppages.

The authors were tasked to design a water supply system from the Odzi River to the

Concession B processing plants. The project involved pumps sizing, pipeline dimension and

material of construction recommendation as well as design of the two intermediate water

reservoirs along the pipeline.

From the values of cost and adequate pump-sizing recommendations, the most appropriate

pipe size option was 10 inches. The 12 inch pipe is the most expensive of the three, the 8 inch

pipeline is less expensive than the 10 inch but from the pump selection calculations the pump

that is compatible with the total head for the 8 inch pipe (93m where pump head from the

KSB pump selection charts for a flow rate of 100 000l/hr was 91m).

Due to lower cost considerations and material characteristics, out of the three materials under

consideration the most desirable were asbestos-cement and high density polyethylene

(HDPE). Asbestos-cement has better characteristics compared to HDPE that is durability and

its resistance to acid and salt corrosion. Fire resistance was also a major attractive quality

upon selection where asbestos-cement had a high fire resistance compared to high density

poly ethylene which is weak in fire resistance. Implementing the use of High Density

Polyethylene as the material of construction for the pipelines would result in lower

maintenance and purchasing costs.

From pump selection calculations the suitable pump for the pump station 1 at Odzi River, is

the KSB ETANORM 80-400. Similar pumps were selected for the first and second stations

since the 2nd pump and the 3rd pump will be in series thus there is need for the same pump to

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avoid pumps cavitation as well as operational design issues. The KSB ETANORM-R 125-

400.R is the most suitable pump for the 2nd and 3rd pump station.

Three options for pipeline material where considered, that using asbestos-cement, high

density polyethylene or steel. The total cost of installing a 15,6km long pipeline from Odzi

River to Concession B of 10 inch diameter, using asbestos-cement as the material of

construction amount to a value of US $1,838,785.00

The total cost of installing a 15,6km long pipeline from Odzi River to Concession B of 10

inch diameter, using high density polyethylene as the material of construction amount to a

value of US $1,721,425.00

The total cost of installing a 15,6km long pipeline from Odzi River to Concession B of 10

inch diameter, using steel as the material of construction amount to a value of

US $3,140,221.00

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Introduction .................................................................................................................................................................................................................. 7

General Objectives ....................................................................................................................................................................................................... 7

Specific Objectives ...................................................................................................................................................................................................... 7

Problem Statement ....................................................................................................................................................................................................... 7

Background .................................................................................................................................................................................................................. 7

Justification .................................................................................................................................................................................................................. 7

Proposed design specifications and calculations ......................................................................................................................................................... 8

Costing ....................................................................................................................................................................................................................... 18

TOTAL COST OF THE WATER SUPPLY SYSTEM PROJECT........................................................................................................................... 22

Recommendations ...................................................................................................................................................................................................... 24

References .................................................................................................................................................................................................................. 24

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ODZI RIVER

Introduction This report serves to show all calculations and considerations carried out by the authors as

well as consultations with other technical people in the organisation.

General Objectives To design an adequate water supply system from Odzi river to Concession B

Specific Objectives 1. To size a pump that will efficiently pump water from Odzi river to an intermediate

pump station below Ushonje mountain

2. To specify accurate pipe line size and material of construction

3. To analyse all possible routes for pipe line layout and determine the best

4. To size pumps that will pump water at the intermediate pump station up the Ushonje

Mountain to the Water Tank

Problem Statement Due to the inadequacy of water at the Concession B there is need to design an efficient water

supply for efficient processing of ore.

Background Initially a pond was constructed at the Concession B to supply water for the Power screen 4

harvesting water from the rains, this pond was supplemented by a 5000l per hour borehole.

An elutriation and a wet feed preparation plants were later added to the facilities in

concession B to increase the diamond ore tonnage required by the dense media separator

(DMS) plants hence the increase in water uptake. The new set-up plants required 20,000l per

hour of water which was coming from the 5000l/hr capacity borehole supplemented by a 30

000l capacity bowser ferrying water from Odzi River which was 20km away.

Justification The major problem being faced at the Concession B is inadequacy of water.

The main water supply has proved to be inadequate to sustain all processing operations. This

is mainly due to lack of an adequate and continuous water supply system. In an effort to

improve the water situation, the water bowser has been utilised to supply water at the

concession B processing plant. The bowser with a carrying capacity of 30 000l can only

manage to supply 90 000l per shift which translates to 11 250l/hr. Current water requirements

at the processing plant amount to 20 000l/hr hence combining the water supply rate from both

the 5 000l/hr borehole and water bowser, report a deficiency in the water circuit.

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The bowser water supply system is very costly as it consumes 336litres of fuel in a day which

amounts to $13 104 in a month hence $157 248 per annum. To efficiently supply the

processing plant, two bowsers would be required the operating cost of which would amount

to $26 208 a month. This cost added to accruing costs incurred upon depreciation of the

vehicle may prove to be very costly for the organisation.

Plans are currently underway to relocate the 65tph Dense Medium Separator (DMS) unit to

the Concession B processing plant which will increase water consumption rate to a value of

around 100 000l/hr. This has been proven to be a beneficial move as transportation of ore

from the concession to the processing plant is highly costly as it amounts to $111 930 per

month in terms of fuel costs for haulage equipment excluding depreciation of the vehicles. To

cheaply and sufficiently sustain water requirements at the concession B processing plant it

would be necessary to construct a pipeline.

Proposed design specifications and calculations

Assumptions

Fluid velocity is constant throughout the system (steady state flow)

Negligible flow resistance on bends

Negligible differential pressures across individual components and flow rates or

velocities within a pipeline.

Pipeline design:

The main aspects of consideration for pipeline design are size, material of construction and

cost. Calculations on similar material pipes ranging from 4-12 inches were devised.

Given data:

Flow rate 100 000l/hr (440gpm)

Pipe size range 4 inches-12 inches

Relative pipe roughness:

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HDPE 0.009

Asbestos-Cement 0.011

Steel 0.012

1. Calculating friction factors for all material for pipe sizes (4-12inches):

Where Reynold’s number, Re

Reynolds’s number:

Where is density of water

u is fluid velocity

d is the pipe diameter

v is the kinematic viscosity of water

PIPE SIZE(INCHES) REYNOLDS

NUMBER(×

4 3.47

6 2.30

8 1.73

10 1.39

12 1.14

Where velocity of flow

Where v is the velocity of flow in feet per second

Q is the flow rate in gallons per minute

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D is the pipe diameter in inches

Pipe Diameter(inch) Velocity Flow(ft/s)

4 11.24

6 4.99

8 2.81

10 1.80

12 1.25

Friction head

where K is the relative pipe roughness

D is the pipe diameter in metres

Re is the Reynolds number

Using the formulae for Reynolds number and friction factor at different pipe diameter and

velocity, the following values of friction factor values were obtained:

Table of friction factor values

TYPE OF MATERIAL

PIPE

SIZE(inches)

ASBESTOS

CEMENT

HDPE STEEL

4 0.10640 0.09528 0.11183

6 0.08570 0.0776 0.08961

8 0.07453 0.0679 0.07768

10 0.06734 0.0617 0.07003

12 0.06269 0.0576 0.06509

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2. Sizing pump 1

Calculating friction head, Hf

Where Hf is the friction head in feet

f is the friction factor

L is the pipe length in feet


v is the velocity flow in ft/s

g is the gravitational force in ft/s2

TYPE OF

PIPE

PIPE SIZE FLUID

VELOCITY

FRICTION

FACTOR

FRICTION

HEAD(metres)

Asbestos 4 11.24 0.1064 346.90

6 4.99 0.0857 36.71

8 2.81 0.0745 7.59

10 1.80 0.0673 2.25

12 1.25 0.0627 0.84

Steel 4 11.24 0.1118 385.99

6 4.99 0.0896 38.39

8 2.81 0.0777 7.91

10 1.80 0.07003 2.34

12 1.25 0.06509 0.88

HDPE 4 11.24 0.09528 310.65

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6 4.99 0.0776 33.24

8 2.81 0.0679 6.92

10 1.80 0.0617 2.06

12 1.25 0.0576 0.77

Calculating total head, Htotal

Htotal = Hstatic + Hf

Where, Hstatic – static head (metres)

Hf – frictional head (metres)

For a static head of 65m,the following values of total head were obtained:

TYPE OF PIPE PIPE SIZE FRICTION

HEAD(m)

TOTAL HEAD(m)

Asbestos 4 346.90 411.90

6 36.71 101.71

8 7.59 72.59

10 2.25 67.25

12 0.84 65.84

Steel 4 348.37 413.37

6 38.39 103.39

8 7.91 72.91

10 2.34 67.34

12 0.88 65.88

HDPE 4 310.65 375.65

6 33.24 98.24

8 6.92 71.92

10 2.06 67.06

12 0.77 65.77

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Isolating values for a flow rate of 100 000l/hr = 440g/m and using these to obtain accurate

pipe sizes from the KSB pipe selection charts attached, two sizes of centrifugal pumps may

be considered:

For an 8, 10 or 12 inch pipeline;

ETANORM 80-400 pump speed (n) =1750 rpm or

ETANORM 125-500.2R n=1450 rpm

3. Sizing pump 2



L - the pipe length in feet




For a pipe length of 3.25km, acceleration due to gravity=32.2ft/s2, the following values of

frictional head where obtained using the equation above

TYPE OF

PIPE

PIPE SIZE FLUID

VELOCITY

FRICTION

FACTOR

FRICTION

HEAD(metres)

Asbestos 4 11.24 0.1064 169.61

6 4.99 0.0857 17.95

8 2.81 0.0745 3.71

10 1.80 0.0673 1.10

12 1.25 0.0627 0.41

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Steel 4 11.24 0.1118 178.26

6 4.99 0.0896 18.77

8 2.81 0.0777 3.87

10 1.80 0.07003 1.14

12 1.25 0.06509 0.43

HDPE 4 11.24 0.09528 151.88

6 4.99 0.0776 16.25

8 2.81 0.0679 3.39

10 1.80 0.0617 1.01

12 1.25 0.0576 0.38

For a static head of 90m the total head values obtained were:

PIPE TYPE Pipe size(inches) Friction

head(metres)

Total head(metres)

Asbestos 4 346.90 259.61

6 36.71 107.95

8 7.59 93.71

10 2.25 91.1

12 0.84 90.41

Steel 4 348.37 268.26

6 38.39 108.77

8 7.91 93.87

10 2.34 91.14

12 0.88 90.43

HDPE 4 310.65 241.88

6 33.24 106.25

8 6.92 93.39

10 2.06 91.01

12 0.77 90.38

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Isolating values for flow rate of 100 000l/hr = 440g/m and using these to obtain accurate pipe

sizes from the KSB pipe selection charts attached, two sizes of centrifugal pumps may be

considered:

For an 8 inch pipeline;

ETANORM 125-500.2R n=1450 rpm

For a 10 or 12 inch pipeline;

ETANORM 125-400 n=1750 rpm

Sizing pump 3



L is the pipe length in feet




For a pipe length of 1km, acceleration due to gravity=32.2ft/s2, the following values of

frictional head where obtained using the equation above

TYPE OF

PIPE

PIPE SIZE FLUID

VELOCITY

FRICTION

FACTOR

FRICTION

HEAD(metres)

Asbestos 4 11.24 0.1064 52.2

6 4.99 0.0857 5.54

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8 2.81 0.0745 1.14

10 1.80 0.0673 0.34

12 1.25 0.0627 0.13

Steel 4 11.24 0.1118 54.86

6 4.99 0.0896 5.83

8 2.81 0.0777 1.19

10 1.80 0.07003 0.35

12 1.25 0.06509 0.13

HDPE 4 11.24 0.09528 31.16

6 4.99 0.0776 5.01

8 2.81 0.0679 1.04

10 1.80 0.0617 0.31

12 1.25 0.0576 0.12

For a static head of 90m the total head values are:

TYPE OF SIZE PIPE SIZE

(inches)

FRICTION HEAD

(metres)

TOTAL HEAD

(metres)

Asbestos 4 346.90 142.2

6 36.71 95.54

8 7.59 91.14

10 2.25 90.34

12 0.84 90.13

Steel 4 348.37 144.86

6 38.39 95.83

8 7.91 91.19

10 2.34 90.35

12 0.88 90.13

HDPE 4 310.65 121.16

6 33.24 95.01

8 6.92 91.04

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10 2.06 90.31

12 0.77 90.12

Isolating values for flow rate (100 000l/hr = 440g/m) and using these to obtain accurate pipe

sizes from the KSB pipe selection charts attached, three sizes of centrifugal pumps may be

considered:

For a 6,8,10 or 12 inch pipeline;

ETA 80-250 pump speed (n) =2900 rpm or


For a 8,10 or 12 inch pipeline;


PIPELINE MATERIAL SELECTION

Three materials for pipelines were considered for sizes, 8- 12 inches, these are steel, HDPE

and Asbestos-Cement. Upon selection of the most appropriate material the following

characteristics were put into consideration.

Carrying capacity.

Durability.

Fire resistance

Maintenance cost.

Type of water to be conveyed

MATERIAL OF CONSTRUCTION

CHARACTERISTICS ASBESTOS-

CEMENT

STEEL HDPE

Carrying capacity.

Sizes are 100mm to

600mm diameter(18

inches)

diameter no greater

than 16 inches

Only available

350mm(12 inches)

diameter

Durability. Average life Less durable where

effects of corrosion

Expected life

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is 30 years.

may be considered is 25 years.

Corrosion resistance

Immune to actions

of acids, salts, soil

and corrosion

Require coating to

minimise effects of

corrosion

High corrosion

resistance

Maintenance cost.

Less plumbing cost

due to less friction

High maintenance

charges are required.

Easy to handle.

Type of fluid to be

conveyed

Water Oil/petroleum and in

some instances raw

water

Water

In terms of capacity, type of fluid conveyed all three materials of construction could be

considered as appropriate. However, asbestos-cement and High Density Polyethylene may be

regarded as the most appropriate material of construction due to their low costs and

favourable characteristics.

Costing

1. Cost of pipeline

One of the most significant considerations for material selection was cost of purchasing the

material for the 15,6km pipeline.

MATERIAL OF CONSTRUCTION COST IN US$

PIPE SIZE(Inches) ASBESTOS-

CEMENT

STEEL HDPE

8 1,136,070.00 1,783,834.00 1,096,524.00

10 1,526,070.00 2,709,200.00 1,419,379.00

12 2,221,284.00 3,773,403.00 2,188,589.00

In terms of cost considerations, HDPE is the most favourable, however its low fire resistance

is a tremendous disadvantage when considering location of the pipeline as this may be prone

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to veld fires etc. Asbestos-cement would thus be the second best option to consider in terms

of cost.

The cheapest pipe size to consider for a flow rate of 100 000l/hr would be 10 inches as an 8

inch pipeline would be ‘nailing the hammer plate’ with pump size considerations.

2. Pump cost

PUMP TYPE(all KSB) PUMP SPEED (rpm) COST IN US ($)

Etanorm 125 - 400 1750 9,318.00

Etanorm 80-400 1750 3,184.00

Etanorm 125 – 500.2R 1450 6,971.00

3. Cost of valves and fittings

VALVE TYPE COST OF PROJECT REQUIREMENT

IN US($)

Non-return foot valve x 1 1,200.00

Non return valve x 5 2,848.00

Butterfly valve x 4 2,280.00

TOTAL COST 6,328.00

4. Tanks construction cost

Tank capacity (Litres) Brick Requirements cost in

USD

Cement Requirements cost

in USD($)

200,000 2,276.00 375.00

5,000,000 11,322.00 750.00

TOTAL 13,598.00 1,125.00

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5. Equipment cost

EQUIPMENT PERIOD EXPECTED

FOR HIRE

TOTAL HIRING COST IN

USD ($)

Excavator 3 days 3,360.00

Dozer 3 days 3,360.00

Crane 1 month 24,000.00

TLB 1 week 5,600.00

TOTAL COST IN USD 36,320.00

6. Labour

Boilermakers x 5 (each @ $1,300 per month) $6,500.00

Boilermaker assistant x10 (each @ $800 per month) $8,000.00

Fitter and turner x 2 (each @ $1300 per month) $2,600.00

Fitter and turner assistants x 2 (each @ 800 per month) $1,600.00

Electrician x 1 (each @ $1,300 per month) $1,300.00

Electrician assistant x 1(each @ $800 per month) $ 800.00

Builder x 1(each @ $1,300 per month) $1,300.00

Builder assistant x 1(each @ $800 per month) $ 800.00

Total $22,900.00

7. Power requirements

Calculating the power required by the pumps:

Epump =

Where,

Epump – Pump efficiency

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Water horsepower (WHP) - the theoretical power needed for pumping water (kW)

Brake horsepower (BHP) - the input power needed at the pump shaft (kW)

WHP =

Where Q is the flow rate in litres per second

H is the total head in metres

BHP =

Given pump efficiency for KSB pumps is 76% from system curves,

Therefore for a flow rate of 100 000l/s and head of 65 and 90m, the following values for

brake horsepower were obtained:

PUMP BHP

REQUIREMENTS

SIZE OF GENERATOR TO

BE UTILISED

ETANORM 80-400 23 kW 38 kVA

ETANORM 125 – 400.R 32.1 6kW 50 kVA

The 1st pump station may utilise power from the Zimbabwe Electricity Supply Authority

(ZESA). However, the second and third pumps would require an external power supply

where generators may be used for this purpose.

PUMP STATION GENERATOR POWER

DRAW

COST IN USD($)

2 50 kW 21,728.00

3 50 kW 21,728.00

TOTAL COST US ($) 43,456.00

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TOTAL COST OF THE WATER SUPPLY SYSTEM PROJECT

Option 1 (Asbestos-Cement Pipeline):

Asbestos-cement has better characteristics compared to HDPE that is durability and its

resistance to acid and salt corrosion. Fire resistance was also a major attractive quality upon

selection where asbestos-cement had a high fire resistance compared to high density poly

ethylene which is weak in fire resistance.

Pipeline $1,526,070.00

Valves $ 6,328.00

Equipment cost $ 36,320.00

pumps $ 21,820.00

power $ 43,456.00

Tanks $ 14,723.00

Labour $ 22,900.00

Contingency allowance $ 167,162.00

GRAND TOTAL $1,838,785.00

Converting the amount in production terms where 1 carat = $50, the total cost of constructing

the water supply system using Asbestos-cement as the material of construction for the

pipeline is 36,775 carats.

Option 2 (High Density Polyethylene Pipeline):

The second option would be implementing the use of High Density Polyethylene as the

material of construction for the pipelines.

High Density Polyethylene has lower maintenance and purchasing costs than Asbestos-

cement in spite of asbestos-cement’s high durability.

HDPE pipeline $1,419,379.00

Valves $ 6,328.00


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power $ 43,456.00

pumps $ 21,820.00

Tanks $ 14,723.00

Labour $ 22,900.00




the water supply system using is HDPE as the material of construction for the high density

polyethylene pipeline is 34,428 carats.

Option 3 (Steel Pipeline):

The third option would be to implement the use of steel as the material of construction for the

pipeline. Steel however, is less durable than asbestos-cement and may require coating to

minimise effects of corrosion. Steel is also very expensive upon purchasing and high

maintenance costs may be incurred.

Steel pipeline $2,709,200.00

Valves $ 6,328.00


power $ 43,456.00

pumps $ 21,820.00

Tanks $ 14,723.00

Labour $ 22,900.00




the water supply system using steel as the material of construction for the pipeline is:

62,804 carats.

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Recommendations The most suitable design would be that of constructing a 15,6km asbestos-cement pipeline

with three pump stations.

Asbestos-cement has a high durability (average life of 30years) thus, it is a long-term

investment. Its high corrosion resistance and fire resistance also make it highly favourable

particularly where the pipeline may be exposed to veld fires and vandalism. Less friction in

asbestos-cement pipes also results in less pumping costs. Costs of purchasing an asbestos-

cement pipeline are quite affordable as they are much cheaper than those of purchasing a

steel pipeline and slightly higher than high density polyethylene.

The 1st pump station will utilise a KSB ETANORM 80-400 centrifugal pump while the 2nd

and 3rd pump stations will utilise KSB ETANORM 125 – 400.R centrifugal pumps. The

pipeline will be fitted with water taps to allow the community to tap and utilise water for their

domestic purposes. This will reinforce and enhance Marange Resources’ corporate-social

responsibility initiatives for the Marange community.

Two concrete tanks reinforced with steel the 1st with a water-holding capacity of 200,000l

and the 2nd with a water-holding capacity of 5,000,000l will also be constructed

References 1. Applied Thermodynamics. Estop and Mckonkey

2. Perry’s handbook for Chemical Engineers, Robert Perry &Don Green.1934

3. www.fluidflowinfo.com

4. www.sciencedirect.com/science/journal

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Marange Resources Water Supply System Design-Odzi to Concession Pipeline