THE COPPERBELT UNIVERSITY

School of Mines and Mineral SciencesChemical Engineering Department

NAMES: BEELE WAMULUME 09198533

KALUMPILA MWANDILA 09196242

MULOSA JONATHAN 09194996

PROG: Beng Chemical 5SUPERVISOR: MR C. BOTHA

© 2014

TITLE

HYDROMETALLURGICAL COPPER PROCESSING

PLANT DESIGN

INTRODUCTION

This project is about the design of a Hydrometallurgical Copper Processing Plant mainly for small scale miners.

The project looks at a paradigm shift from the conventional large scale processing of copper to small scale processing of copper affordable to local investors.

HYPOTHESIS

The plant to be designed will be able to

process 15 metric tonnes of copper ore per

day with 80% recovery. It will be economical,

cost effective and affordable for average local

investors.

AIM

The project was aimed at designing a Hydrometallurgical Copper Processing Plant on a small scale that would process about 15 tons of copper oxide ore per day and recover over 80% of copper.

SPECIFIC OBJECTIVES

1. To establish the most economical hydrometallurgical technique for the treatment of copper ore.

2. To carry out theoretical material balances of the plant and to establish the feed rate required.

3. To carry out an energy balance of the hydrometallurgical plant and establish the power required to operate the plant.

4. To determine the types and sizes of the equipment required.

5. To determine the capital cost of the plant.

Methodology

Part of the design work was based on the laboratory experiments and the other part was theoretical.

The work was divided in the following phases: Data Collection Laboratory Experiments Process Design Mechanical Design Project Costing

Laboratory experiments

• Comminution –obtain optimum particle size (75-100 microns)

• Leaching (determine leaching residence time )

• Cu assays (determine extraction efficiency)

• Batch settling tests (determine settling rates for slurry)

Process design

The work in this stage involved; • Determination of the appropriate feed rate

for a small scale plant.• The theoretical material and energy

balances of the overall plant and the individual units.

• Recovery, plant attainment and overall efficiency

Mechanical design

The work involved in this stage included;• Selection of appropriate equipment.• Sizing of the equipment• Selecting the appropriate materials of

construction to be used.

Mechanical design equations

• Reactor Volume…..

• Wall thickness of vessels

• Area of clarifier

• Power required for agitation

Project costing

• Cost of different equipment was obtained from reliable internet vendors.

• The material costs for the equipment fabricated on sight was also obtained from the internet. 40% was added for labor costs.

RESULTS

Summary of material and energy balances

INPUT OUTPUT EFFICIENCY

Cu ore 1.5t/h (6wt%) 1.34t/h (99.9wt%)

90%

Fresh water 35m3/hr 0 100%(assuming no spillages/leaks)

Sulphuric acid 1.6m3/hr 0.029m3/hr 98.2%

Organic solvent (17.9% LIX 984N; 82.1% diluent)

17m3 0 100% (recycle of the organic)

Power (13cents/kWh)

112kW - -

RESULTS

Comminution Circuit

Model PE-150

Inlet Size (mm) 150×250

Maximum feeding size (mm) 125

Adjusting range of size (mm) 15-45

Capacity (t/h) 1.2-3.5

Motor (KW) 5.5

Weight (t) 0.8

Overall dimensions (L×W×H) (mm)950x1100x1100

FOB Price (USD) 1650.00

Table 4.1 jaw crusher specifications

Cont…

Model 2YK 1237

Screen Spec (mm) 1200 × 3700

Maximum feeding size (mm) 200

Screen mesh size (mm) 4-50

Capacity (t/h) 15-86

Motor (KW) 15

Layers 2

Vibrating frequency (r/min) 960

FOB price (usd) 5000

Table 4.2 vibrating screen specifications

Cont…

Table 4.3 ball mill specifications

Cont.…

Model FX125

Diameter (mm) 125

Maximum feeding size

(mm)

0.6

Feeding Pressure

(MPa)

0.06-0.35

Capacity (m3) 8-15

Classification Size

(μm)

20-100

Weight (kg) 10

Overall dimensions

(L×W×H) (mm)

210x185x620

FOB price (usd) 100.00

Table 4.4 hydro cyclone specifications

Table 4.5 thickener design results

Parameter Dimensions

Diameter of thickener 10.0m

Height of cylindrical section 2.0m

Surface area of cylindrical section (m2) 62.8 63

Outlet diameter 1.0m

Volume of the cone 65.4m3

Surface area of the cone 25.868m2

Volume of the cylindrical section 157.1m3

Total surface are of thickener (m2) 90

Power requirement (kW) 0.12

Material of construction of shell Carbon steel

Thickness of shell 10mm

Material of construction of lining Vulcanized Latex

rubber

Thickness of lining (mm) 20

Total volume of shell (m3) 0.9 1

Total dead weight of thickener (t) 7.9 (steel shell) +

1.92 = 9.82 10

Total cost of rubber (mass of rubber (kg) × $2.50 (usd) 5000

Total cost of steel (hot rolled plate)(mass of steel (t) × $700

(usd)

5600

Total cost of thickener shell manufacture (usd) 15000

Cont.…

Mass of ore (Kg) 1500

Residence time (h) 3

Diameter of leach tank (m) 2

Height of leach tank (m) 2

Power (KW) 0.2

Torque (KW/rps) 0.03

Residue acid mass (pH=2) Kg 40.58

Tank thickness (mm) 9

Plate thickness (mm) 40

Impeller diameter (mm) 700

Table 4.6 Leaching Circuit

Cont.…

Over flow rate (m3/h) 1.5

Under flow rate (m3/h) 2.7

Copper Concentration In Overflow (g/l) 18.1

Average area (m2) 2.2

Diameter (m) 1.7

Cone angle (°) 30

Torque (Nm) 1530.2

Gearbox output speed (rpm) 0.378

Power (KW) 0.12

Clarifier thickness (mm) 10

Rubber lining thickness (mm) 5

Settling pond volume (m3) 302

Table 4.7 Solution Purification

Cont.…

Concentration of copper in PLS(g/l) 18.1

Extractant LIX 984N/LIX 973N

Mixing time (min) 15

Diameter of a mixer (m) 1

Height of a mixer (m) 2

Impeller diameter (mm) 330

Separation time (min) 30

Height of settler (m) 1

Length of settler (m) 6

Breadth of settler (m) 3

Mixer Construction material Carbon steel with PVC paint coating

Settler Construction material Concrete with PVC lining

Table 4.8 Solvent Extraction

Cont.…

Dimensions (L × W × H)m 4.2 × 1.25 × 1.5

Cost per cell K30 000

Total cost (15 cells) K154 000

Cost per stainless steel plate K16 800

Total cost (300 stainless steel plate) K5 040 000

Cost per anode plate K56

Total cost (315 anode plates) K K17 640

Cost of rectifier  

Total cost (K) K5 300 000

OPERATION  

Cathode production (tonnes /yr.) 518

Electrolytic cell  

Total number 80

Construction material Polymer concrete

Length × width × depth(inside), m 4.8 × 1.25 × 1.5

Anodes, cathodes per cell 20/21

Spaces between anodes and cathodes, mm 95

Anode  

Material % 98.4%Pb, 1.5%Sn, 0.08%Ca, 0.02%Al

Table 4.9 Electrowinning

Length × width × thickness, m 1.1 × 0.9 × 0.006

Center – to - center spacing in cell, mm 95

Life, yr. 5

Cathode  

Type Stainless steel

Length × width × thickness, m 1.2 × 1.0 × 0.003

Side edge strip material PVC

Bottom strip material PVC/RUBBER

Plating time, days 10

Mass Cu plated on blank, Kg 60

Stripping method Hand stripping

Power and energy  

Cathode current density, A/m2 280

Cathode current efficiency, % 98

Cell voltage, V 1.98-2

Cell current, kilo amperes 30

Power kW 60

Electrolyte  

Circulation rate into each cell, m3/minute 0.2

Cont.…

Cont.…

Cu, Kg/m3 45-55

H2SO4, Kg/m3 180-190

Temperature, °C 60-65

Out of cells  

Cu, Kg/m3 40

H2SO4, Kg/m3 200

Temperature, °C 65

Addition rates, g/per tonne of cathode  

Guar gum, ppm 250

Cobalt sulfate, ppm< 150

Chloride ions, ppm < 30

Electrolyte treatments before entering

tank house

Gamet / anthracite filtration, heat exchanger

Site location

• The overriding factor when selecting the site for this plant was the proximity to the main raw material- copper oxide ores.

• Other factors considered included source of electricity, water and proximity to acid source

• Areas suitable for this plant include Kasempa, Mufumbwe and Mumbwa

DISCUSSION

Comminution Circuit

Wet grinding was employed in this plant to reduce energy usage, facilitate removal of material and to suppress dust.

Three hydrocyclones were used to increase efficiency of the plant and also to allow room for expansion of the plant.

The thickener serves two purposes; allows the slurry to be of required density for optimum extraction during leaching and serves as a recycle line for the water to minimize fresh water usage.

Cont…

Leaching Circuit pH was maintained between 1.8-2 to ensure proper extraction

of copper in the leach tank.

Four tanks in parallel were used to achieve a continuous

process.

Cont…

Solid-Liquid Separation Circuit

The separation of solids from the metal laden liquid was the

most difficult separation process to achieve. In the lab, the

separation was effectively using a leaf filter and the washing

done using hot water.

However, on a commercial scale, the raffinate will be used to

wash the gangue solids

The thickener will employed to facilitate the continuous

separation of solids from the metal laden liquid.

Cont…

Solvent Extraction Circuit The circuit is made up of 2 extraction stages and 1-

stripping stages. The PVC material will be used for lining the settler which

will be made of concrete.

Electrowinning The number of cathodes was determined for a 10 days

standard for electroplating 60 kg of copper on each cathode to be 22 per cell.

Polymer concrete cells were used.

Cont…

Summary The total cost of the plant was determined to be $1.1

million (K5.8million). Adding 40% for installation, civil works and electrical works the total comes to about $1.5 million dollars (K8.5 million).

CONCLUSIONS

A material balances and energy balances of the plant was conducted and the plant was determined to have an efficiency of at least 90%. The feed rate for the copper ore was determined to be 1.5 tonnes per hour. The power requirements of the plant was about 120kW (costing the plant K2000/day on energy). The total copper output of the plant is about 1,900kg copper per day giving an annual output of 583 tonnes.

The capital cost of the plant was determined to be $1.5million dollars (K8.5 million).

Small scale hydrometallurgical processing is a very viable project for a developing country like Zambia. It will enable empowerment of Zambians in an industry dominated by foreign multinational companies.

RECOMMENDATIONS

Small scale hydrometallurgical processing is a very viable project. And This can easily be achieved if a team of different specialists come together to start the plant.

The use of plant design software will help optimize the plant more accurately.

The structural and mechanical design of the plant should be carried out by more specialized structural and mechanical engineers.

Other areas which require specialists include instrumentation, civil works, electrical works and detailed costing.

REFERENCES

1. Brownell, L.E., and Young, E.H. (1959) Process Equipment Design, New York, John Wiley and Sons, Inc.

2. Chiranjib, K.G. (2003) Chemical Metallurgy, (1sted), Mumbai, India: John Wiley publishers.

3. Davenport W.G. (2002) extractive metallurgy of copper, (4thed), university of Missouri, USA.

4. Greenwood, N.N. and Earnshaw, A. (1984) Chemistry of the Elements, (2nded), U.K., Reed Education and Profession Publishing Ltd.

5. Kolthoff, Sandell, and Meehan. (1969) Quantitative Chemical Analysis, (4th edition), U.S.A, The MacMillan Company.

6. Mark, E. eta’l (2004) Extractive Metallurgy of copper, (5thed), Amsterdam, Netherlands: Elsevier.

7. Martin, R. (2008) Introduction to particle technology, (2nd edition), Monash university, Australia: John Wiley & sons.

Cont…

8. Max, S.P., and Klaus D.T. (1991)Plant Design and Economics for Chemical Engineers, (4thed),New York St. Louis, McGraw-Hill, Inc.

9. McCabe, W.L., Smith, J.C., and Harriott, P., (1987) Unit Operations of Chemical Engineering, (4thed), Singapore, McGraw-Hill Book Company.

10.Pierce, Haenisch, and Sawyer. (1958) Quantitative Analysis, (4thed), U.S.A., John Wiley and Sons, Inc.

11. Sinnot, R.K. (2005) Chemical Engineering Design, (volume 6), London, Elsevier Butterworth Heinemann

12.Speight, J.G. (2002) Chemical and Process Design Handbook, New York, McGraw - Hill.

13.Steve, M. (2004) The IDC Engineers pocket Guide, (5th edition), West Perth, Australia: IDC Technologies

14.Strouts, C.R., Wilson, H.N., and Parry, R.T. (1967) Chemical Analysis, (Vol. 2), U.K., Oxford University Press.

15.Swift, E.N. (1972) Quantitative Measurements and Chemical Equilibria, USA, W.H. Freeman and Company.

THE END

Thank you…!