Alfa Laval Ab · OMXSTO:ALFA
Alfa Laval Ab — ICSOBA 2015 – 33rd International Conference and Exhibition
41 slides from Alfa Laval Ab's conference presentation, November 2015
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Slide 2: Solid bowl decanter: sustainable solid/liquid separation in mining and mineral industry
Solid bowl decanter SUSTAINABLE SOLID/LIQUID SEPARATION IN MINING AND MINERAL INDUSTRY Ivar Madsen, Business Unit Manager Dubai, 29 Nov – 1 Dec 2015 Marcelo Gabriel, Sales Manager © AlfaSlide Laval2 www.alfalaval.com
Slide 3: As presented at ICSOBA 2015
As presented at ICSOBA 2015 The International Committee for Study of Bauxite, Alumina & Aluminium 33rd International Conference and Exhibition ICSOBA-2015, "Global and Gulf Region Developments in Bauxite, Alumina and Aluminium Production” © Alfa Laval Slide 3 www.alfalaval.com
Slide 4: Agenda
Agenda • Introduction to Alfa Laval • Technology development of solid bowl decanter centrifuge • Operational examples from the mining and mineral world • Results obtained in Alumina industry • Conclusions and discussions
Slide 5: Our corporate mission
Our corporate mission To optimize the performance of our customers’ processes. Time and time again.
Slide 6: The processes we are in
The processes we are in We help customers to heat, cool, separate and transport products such as oil, water, chemicals, beverages, foodstuff, starch and pharmaceuticals.
Slide 7: We serve most industries
We serve most industries Biofuels Metal working Biotech and pharmaceutical Mining and mineral processing Chemicals Oil and gas Engine and transport Oil refinery Fluid power Power Food and beverages Pulp and paper HVAC Refrigeration and air-conditioning Industrial fermentation Semiconductor systems L
Slide 8: Gustaf de Laval (1845-1913)
Gustaf de Laval (1845-1913) “The man of high speed” • 200 projects and inventions • 92 patents, including the milk separator (1878) and the steam turbine (1883) • Started 37 companies
Slide 9: Key technologies
Key technologies Our key technologies are adapted to each customer segment and offered separately or combined into optimized solutions.
Slide 10: Agenda
Agenda • Introduction to Alfa Laval • Technology development of solid bowl decanter centrifuge • Operational examples from the mining and mineral world • Results obtained in Alumina industry • Conclusions and discussions
Slide 11: Where it all begins – Stokes' law
Where it all begins – Stokes’ law 2 d ( p - l )g Vg = 18 Vg = gravitational settling velocity d = particle diameter p = particle density l = liquid phase density = liquid phase viscosity Sir George Gabriel Stokes, 1st Baronet (1819–1903) g = gravitational acceleration
Slide 12: Based on the concept of a clarifier
Based on the concept of a clarifier © Alfa Laval Slide 12
Slide 13: Technology development
Technology development Solid bowl decanter centrifuge • Sigma [Ʃ] historical use to define separation efficiency • Have some limitations – but most decanter centrifuge suppliers are using it in some format • In real life – solids handling is often the limiting factor
Slide 14: What is a decanter centrifuge?
What is a decanter centrifuge?
Slide 15: What is a decanter centrifuge?
What is a decanter centrifuge? 1. Back drive 2. Frame and 3. Adjustable 5. Wear-resistant 6. Feed 7. Solids 8. Heavy-duty system casing pond depth & conveyor flights zone discharge bearings power plates 4. Bowl and conveyor
Slide 16: Parameters influencing separation
Parameters influencing separation Process parameters Decanter design • Feed rate (Q) • Bowl speed (g-force) • Particle size (polymer addition) • Conveyor differential (_n) • Viscosity (heating) • Pond depth (R-r)
Slide 17: What is a mining decanter centrifuge?
What is a mining decanter centrifuge? • A decanter designed to handle large capacity, highly erosive feed, catch of fine particle, lower energy consumption • Capable of handling up to 350 m3/h @ 100 t DS / h per unit • Highly dry cake, easy to stack and more water for recovery
Slide 18: Solid/liquid separation
Solid/liquid separation Technologies used today 10000 Decanter 9000 8000 Filter technology 7000 6000 M3/h Gravity based 5000 4000 3000 2000 1000 0 0.1 1 10 100 1000 Particle size - microns
Slide 19: New for mining and mineral industry
New for mining and mineral industry Deep pond technology • Allows to handle exceptional amounts of solids • Enhances separation Conventional bowl geometry and catch the finest • Powers power consumption – less kinetic energy is lost from the system Deep pond bowl geometry
Slide 20: Enhanced scrolling capacity
Enhanced scrolling capacity Solids restriction puts hydro-static pressure on the solids Helps the solids out of the decanter Optimized cone angle facilitates scrolling of highly dense cake
Slide 21: Erosion protection – more than usual
Erosion protection – more than usual • Fully protected from inlet to outlet • Tungsten Carbide widly used © Alfa Laval Slide 21
Slide 22: Agenda
Agenda • Introduction to Alfa Laval • Technology development of solid bowl decanter centrifuge • Operational examples from the mining and mineral world • Results obtained in Alumina industry • Conclusions and discussions
Slide 23: Example from mining & mineral world
Example from mining & mineral world • Separation of tailings from a saturated borate solution • Solids: dolomite, clay, quartz • 96ºC, pH= 9–10 • D50 solids: 14 micron • Solids specific gravity: ~2.45 kg/dm3 • Feed: ~20% w/w • Cake: ~70% w/w
Slide 24: Example from mining & mineral world
Example from mining & mineral world • Dewatering of fine coal tailings from a coal washing plant • Solids: coal solids, slime, clay • Particle size: 5–50 micron • Solids specific gravity: ~ 1.55 kg/dm3 • Feed: ~35–40% w/w • Cake: ~65–70% w/w • Several conventional dewatering technologies were tested
Slide 25: Example from mining & mineral world
Example from mining & mineral world • Mature fine tailings: clays, quartz (sand), bitumen and water • Solids specific gravity: ~ 2.65 kg/dm3 • Solids: kaolinite, illinite and quartz • D50 solids = 10 micron • Feed: ~30% w/w • Cake: ~55% w/w • Tests proved that the resulting cake is stackable
Slide 26: Agenda
Agenda • Introduction to Alfa Laval • Technology development of solid bowl decanter centrifuge • Operational examples from the mining and mineral world • Results obtained in Alumina industry • Conclusions and discussions
Slide 27: Red mud separation
Red mud separation Bayer process • Red mud, named after its bauxite slurry color, is the main by-product of caustic soda making alumina by the Bayer Mixing process • The red mud is separated from Digestion the pregnant liquor (sodium aluminate remains in solution) red mud via sedimentation in a clar
Slide 28: Current dewatering technology
Current dewatering technology (1) Deep Cone Washers • typical solids content of the underflow in the last washer is 50% w/w (2) Vacuum Drum Filter • solids content of the cake: 50-65% w/w • filter cake consistency: sticky mud
Slide 29: Current dewatering technology
Current dewatering technology (3) Filter Press • solids content of the cake: 70%w w/w • stackable cake • questionable if filtrate is sufficient quality in all cases
Slide 30: Test conducted
Test conducted • Pilot test in alumina plant in Australia • Red mud dewatering/Caustic recovery • Feed SG: ~1.55-1.65 • Solids SG: 3.30 • pH: > 14 • Temp: 70 - 80 oC • Particle D50= 30 microns
Slide 31: Test conducted
Test conducted • Caustic soda recovery (20 g/L) • Water recovery • Cake: 70 - 75% w/w • Produce stackable cake (eliminate installation of new pond)
Slide 32: Test conducted
Test conducted • Pilot test in alumina plant in Brazil • Red mud dewatering • Washer underflow (booster to washer)
Slide 33: Test conducted – 3 different feeds
Test conducted – 3 different feeds RVF React 3 3 2 1
Slide 34: Results – test (1)
Results – test (1) Cake dryness vs. recovery 100,00 90,00 80,00 70,00 Recovery [%] 60,00 50,00 wFlocculent Nalco polytype 1 40,00 Without poly type 2 Flocculent 30,00 20,00 10,00 0,00 60,0 65,0 70,0 75,0 Cake conc. [w/w% TS]
Slide 35: Results – test (2)
Results – test (2) Cake dryness vs. recovery 100,00 90,00 80,00 70,00 60,00 Flocculent nalco poly type 1 50,00 Zytec Flocculent type 2 40,00 30,00 20,00 10,00 0,00 55,0 60,0 65,0 70,0 75,0
Slide 36: Test to be done – (3)
Test to be done – (3) • Booster to current washer step (1 and 2) • Objective to improve uptime of washer stage – e.g. from heavy scaling • Other benefits - to be defined
Slide 37: Agenda
Agenda • Introduction to Alfa Laval • Technology development of solid bowl decanter centrifuge • Operational examples from the mining and mineral world • Results obtained in Alumina industry • Conclusions and discussions
Slide 38: Benefits of decanter centrifuges
Benefits of decanter centrifuges • Competitive CAPEX and OPEX, and short payback time • Capable of handling a wide range of solid- liquid separation duties • Handles everything from ultrafine to coarse tailings • Water can be recovered by having a decanter centrifuge operating in parallel with a tai
Slide 39: Summary
Summary • Dewatering of red mud can be done in a decanter • Cake dryness in the range of 70% - 75% can be achieved • Recovery in the range of 95 – 99% can be achieved • Correct polymer have major impact on performance • Further test will define − Polymer optimization (type, dosing, concentration, et
Slide 40: Thank you
Thank you © Alfa Laval Slide 40 www.alfalaval.com
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