Zero liquid discharge in mining and metallurgy

• GEA Organization
• GEA Filtration
• Wastewater in mining and metallurgy
• Conventional treatment
• Reverse Osmosis Design
• Operational Parameters

Organisational Structure GEA

GEA Group
Process Engineering		Process Equipment		Customized Systems		Plant Engineering
Process Engineering Energy Technology		Mechanical Separation Process Equipment Dairy Farm Systems		Air Treatment Refrigeration		Lurgi Lurgi Lentjes Zimmer

Process Engineering Segmen

Major Companies of the Process Engineering Segmen:

• Niro A/S
• Aeromatic-Fielder
• GEA Barr-Rosin
• Collette NV
• Courtoy NV
• GEA Wiegand GmbH
• GEA Liquid Processing Scandinavia
• GEA Kestner SAS
• GEA Messo GmbH
• GEA Jet Pumps GmbH
• Niro Pharma Systems
• Tuchenhagen Brewery Systems
• Tuchenhagen Dairy Systems

GEA Filtration Organisation

Fields of operation GEA Filtration

• Technology Leader
• Global Player
• Engage only in selected process segments
  • Dairy , Food & Beverage, Pharmaceuticals, Industrial
• Provide a choice of state of the art membrane configurations – Spiral wound, Ceramic, stainless steel, hollow fiber etc....
• Differentiate from others by providing a complete solutions - package of services to our customers
  • Pilot testing and process development capabilities
  • Process scale up
  • Complete system design and fabrication
  • Validation services
  • After sales service including replacement membrane services
• Organic Growth
• Opportunistic acquisition of niche separation technology companies

Dairy Industry

• Milk
• Cheese
• Whey Products
• Cultured Dairy products
• Ice Cream
• Water & Product Reclamation
• Process Effluent treatment
• Cleaning Chemical recovery

Food & Beverage

• Vegetable products: Fruit / Vegetable Juices
• Grain Products: Soy isolate, wheat proteins
• Sugar, Starch and Sweetener: Beet and Cane; corn, wheat, rice, Tapioca etc. products
• Plant extracts: Coffee, tea, herbal, oil seeds
• Beverage: Breweries, wineries, potable alcohol, soft drinks
• Animal products: Blood, gelatin, rendering, eggs, poultry
• Fish & Seafood Products: Proteins
• Bio-food: Products from Fermentation – e.g. organic acids
• Water reclamation
• Process Effluents
• CIP Chemical recovery

Industrial Applications

• Bio-chemicals: Chemicals derived from Fermentation processes e.g. bio-plastics, bio-insecticides, bio-pesticides, organic acids
• Distillery products: Industrial alcohol, yeast
• Enzymes
• Pigments and dyes
• Fine Chemicals
• Water reclamation
• Process Effluents
• CIP Chemical recovery

Zero Discharge in Mining and Metallurgy

• Elimination of liquid waste
• Concentration of all pollutants in solid phase
• Reduction of fresh water demand by reuse of purified wastewater
• Protection of natural resources
• Reduction of disposal cost

Technologies for Zero Discharge

Involved Process Technologies and corresponding GEA company with specific Know-How:

• Chemical / Physical water treatment: Messo
• Conventional Filter technologies: Messo / Wiegand
• Membrane Filtration: Messo / Wiegand / Niro
• Evaporation: Messo / Wiegand / Niro
• Crystallization: Messo / Kestner / Wiegand
• Drying: GEA Barr-Rosin / Niro

Wastewater in Mining and Metallury

Water pollutants:

• Heavy metals
• Iron
• Calcium, Magnesium
• Trace elements: Strontium, Barium
• Oils, Emulsions
• Unspecific COD

Conventional treatment

Conventional treatments:

• Precipitation: Heavy metals
• Oxidation: Iron
• Oil-Skimmer, Flotation: Oils, Emulsions
• Sedimentation
• Filter press for dewatering of sludge's

Limits:

• Insufficient qualities for water reuse
• Insufficient educts qualities for discharge due to tighter legislative regulations

Optimisation of conventional treatment

Oxidation:

• Operation:
  • Oxidation of iron and manganese
  • Oxidation of heavy metals
• Target: Precipitation of the corresponding hydroxides

Precipitation: Optimization of precipitation (reaction time, addition of crystallization nuclei, addition of ferric chloride...)

Lime softening (addition of hydrated lime)

Ca(HCO3)2 + Ca(OH)2		2 CaCO3 + 2 H2O
Mg(HCO3)2 + 2 Ca(OH)2		Mg(OH)2 + CaCO3 + 2 H2O

Reduction of: - Carbonate hardness, barium, strontium, heavy metal - hydroxides, organics

Soda-ash process:

CaCl2 + Na2CO3

2 NaCl + CaCO3

Reduction of: - Noncarbonate calcium hardness, silica, aluminum, iron

Filtration:

Chemical pretreatment:

• Acidification: Acidification of reverse osmosis feed in order to rise solubility's
• Antiscalant: Addition of Antiscalant to rise precipitation concentrations

Chemical pretreatment:

• Acidification: Acidification of reverse osmosis feed in order to rise solubility's
• Antiscalant: Addition of Antiscalant to rise precipitation concentrations

Reverse osmosis in Mining and Metallurgy

Possible risks/limitations:

• Suspended solids, Turbidity
• Fouling: Iron, Alumina, Silica
• Precipitation: Hardness (Ca, Mg), Bariumsulfat, Strontiomsulfat

Feed characteristics for Reverse Osmosis Process

Feed and design characteristics:

• Potential risk of suspended material in feed (high SDI-value)
• Potential risk of fouling due to iron in feed
• High salinity feed-stream
• Low pH-feed
• Elevated feed-temperatures are favorable (lower operational pressures, higher solubility's)
• Extreme rise of osmotic pressure at higher recoveries

Membrane selection

Membrane selection criteria:

• Operational range of pH must be high
• Larger feed-spacer: low impact of fouling (pressure drop) better cleanability
• High nominal rejection in order to optimize permeate qualities (seawater membrane)
• High pressure design for membrane (seawater membrane)

Design Considerations

• Loop-Configuration is favorable to provide ideal cross-flow conditions for membrane elements
• Booster-pumps are necessary to compensate rising osmotic pressures between stages
• Conservative specific flux rates (approx. 15 lmh) to minimize fouling tendencies and increase operating times
• Frequency controlled pressure pumps to minimize energy consumption
• Safety considerations to provide maximum availability
• Corrosion resistant materials due to high salt contents

Exemplary Flow diagram

Sizing calculation of exemplary wastewater

Feed Composition:			Recovery	Osmotic Pressure	Filtration pressure
NH3	2.800	mg/l	40 %	11 bar	23 bar
Na	2.200	mg/l	65 %	19 bar	34 bar
Cl	400	mg/l	80 %	34 bar	48 bar
SO4	11.500	mg/l

Calculation based on High Rejection Seawater membrane at 40 °C filtration-temperature.

Confirmation of water composition by trials

• Continuous operation of optimized pretreatment
• Continuous operation of reverse osmosis
• Cleaning trial
• Membrane autopsy after trials
• Concentrate out of membrane plant goes to further treatment:
  • Evaporation by falling-film evaporator with mechanical vapor recompression (MVR)
  • Crystallization in forced circulation evaporator

Exemplary pilotplant execution for pretreatment and reverse osmosis operation

Results from pilotisation

Pilotisation Results:

	Feed	Permeate	Concentrate
Total solids	14.600 – 16.300 ppm	200 – 900 ppm	63.000 – 90.000 ppm
Conductivity	13,3 – 19,7 mS/cm	300 – 900 μS/cm	80 – 120 mS/cm
pH	2,7 – 3,3	2,4 – 3,7	2,8 – 3,2
NTU	0,18 – 0,45	0,1 – 0,5	0,3 – 1,7
NH4	2.700 – 3.400 ppm	<10 ppm	13.000 – 14.000 ppm
Na	900 – 2.100 ppm	1 – 90 ppm	2.400 – 7.400 ppm
Cl	370 – 480 ppm	50 – 390 ppm	900 – 1.400 ppm
SO4	10.100 – 13.500 ppm	500 – 3.500 ppm	43.000 – 51.000 ppm

Operational parameters Reverse osmosis

Operational Parameters and consumptions:

Feed Flow:	100 m3/h
Permeate Flow:	80 m3/h
Energy consumption:	230 – 260 kWh
Specific energy:	2,9 – 3,25 kWh/m3
Membrane cost:	120.000 €/a
Citric acid (30 %):	85 m3/a
Caustic (NaOH, 30%):	70 m3/a
Na4EDTA:	2.000 l/a
Steam (during CIP):	500 kg/h
Antiscalant:	2.600 kg/a

Prefiltration Rack

 

Reverse Osmosis Rack

 

Thermal Process

 

Operational parameters Reverse osmosis

Operational Parameters and Consumptions for Thermal Process:

Feed Flow:	22 m3/h
Energy consumption MVR:	560 kWh/h
Consumption steam pre-heating:	2.000 kg/h
Consumption of steam or evaporation:	3.200 kg/h
Antiscalant:	2.600 kg/a
Distillate production thermal process:	21.800 kg/h
Distillate quality TDS	100 ppm
Final Filter Cake approx.	2.300 kg/h

Process Flow Diagram

Falling Film Evaporation (MVR) FC-Evaporator (TVR) Band filter