Download Control of Water Solids Waste in Heavy Industry

Process Systems
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Control of Water Solids Waste
in Heavy Industry
1
Clearing the way from problem to plant.
By the application of simple logic, a complex
problem is broken down to subquestions with Yes/
No answers.
The answers will form the skeleton of a flowsheet.
Analysis of water and solids, test work and
experience will dimension the unit operations.
Metso goes all the way from investigation, process
design, equipment manufacturing as well as
engineering, plant erection and commissioning.
The following is a presentation of some treatment
plants designed and commissioned by Metso.
If you find a similarity with your problem - let’s get
in touch!
2
Clearing the Way from Problems to Plant
Gravity is free of charge.
Our strive in solid/liquid separation
is to use gravity to its maximum.
Lamella sedimentation enables it
to be used in a reasonably compact
installation.
Feed preparation aims to make the
material able to be pumped,
transform the soluble to solids and
to make the solids sink.
What gravity may fail to accomplish
will be settled by force. E.g. sand
filters, magnetic filters or carbon
adsorption for liquid purification,
vacuum filters, belt filters, press
filters for dewatering of solids.
3
Iron and Steel
Steel plants, in general, operate on
a massive scale. Water quantities
are big. Solids from furnaces,
casting and mills are distinct
particles. Straight forward solid
liquid separation applies.
Traditional handling has been in
huge settling basins, pits and filter
batteries.
Treatment of pickling effluents will
call for elaborate treatment of
heavy metals and toxins, as
described on page 8.
Scrubber water
Reagens mixer
Owerflow
water
Flocculator
Clarifying
Thickener
Thickened sludge Vacuum filter
Dewatered
material
Lamella sedimentation promotes area
performance. 700 m3/h of mill effluent
is cleaned in one shop fabricated
Inclined Plate Settler.
Suspended solids in overflow is less
than 50 ppm. Underflow is concentrated to 60% dry solids
s
Iron bearing contaminants are suited
for magnetic trapping. High gradient
magnetic filters Metso HGMF®, operate
with outstanding filtration rates, over
500 m 3/h for mill effluents. The
extreme magnetic forces achieved
also permit removal of weakly
magnetic species, such as oxides
formed in BOF or vacuum degassing
operations.
s
4
The traditional way of scrubber
effluent treatment is sedimentation in
circular clarifier/thickeners. Erection on
legs allows a fit of dewatering and
auxiliary equipment in a compact
fashion. Typically 1000 m3/h can be
treated in a 25 m diameter unit.
s
The lamella technique, continuous
filtration, magnetic filtration and
a general care in forming the plant
layout, will minimize building
volume
with
maintained
availability.
s
Iron and Steel
Use of spiral dewaterers and
continuous sand filters replaces
orthodox scale-pits, sedimentation
basins and back-flush filters in the
treatment of water from continuous
casting and hot milling.
Savings are radical in all aspects - space,
investment, availability, running costs,
maintenance.
s
The spiral dewaterer retrofits scale-pits
in existing plants and runs unattended.
One modular unit with inserted
lamella plates is capable of handling a
feed flow bigger than 2000 m3/h.
Scale discharge contains just a few
percent moisture
s
The spiral dewaterer does the tough
job in separating the material > 0.1
mm. The dewatered oxide scale is dry
with a moisture content of approx 5%
or less.
Pumping of scale and scrap is simple
routine with Metso sump pumps and
allows the clean-up system to be freely
located. The wear parts in the rigidly
designed Metso pumps will in many
cases last for years.
5
Metals and Metallurgy.
The poisonous nature of these
substances calls for:
• Far going circulation of the
water
• Elaborate treatment of water
bleed off
• Stabilisation of disposal
products
• Controlled disposal
• Reclamation of solids when
possible.
6
s
Contamination with heavy metals
and toxic compounds are
unavoidable in many industrial
processes. They may hide in
soluble form in a visibly clear
effluent. When precipitated, they
can be separated as solids.
Boliden developed the Kaldo Process
for lead production. Based on samples
from pilot tests, Metso designed the
water treatment process with
recycling of both water and solids.
Scrubber
The treatment involves stepwise
precipitation of heavy metals under
controlled conditions, and dewatering
and drying of solids for reclamation in
the process. The corrosion conditions
were severe and met by rubber lining,
plastic coating or plastic design of the
process equipment.
Recycling
material
Caldo
owen
Drumfilter
Chemical
dosage
Dryer
Clarification
Sedimentation
Thickening
s
Metals and Metallurgy
The use of lamella sedimentation techniques makes
possible the installation of a full process plant in less than
the space of a conventional clarifier.
This plant, serving the scrubber water system of a kryolite
furnace, treats 120 m3/h of water for circulation. Solids,
dewatered on a belt drum filter, are bound in concrete
blocks for safe disposal. The concrete handling is man
operated on daytime whereas the water treatment runs
unmanned continuously.
s
Production of ferro-chromium, in carbon/anthracite
electrode furnaces and with coke as reduction medium,
may apart from metal fumes give raise to formation of
polyaromatic hydrocarbons (PAH) in the furnace gases.
The feed, 200 m3/h, is flocculated and clarified in one
lamella clarifier/thickener with pH-control. A substantial
part of the PAH content is removed already in this step.
A maximum part of the water, over 80%, is
reused after cooling. The bleed is polished
in sand filters and carbon adsorption
columns to safeguard effluent standards
before stream discharge.
The plant runs unattended over a PLC, with
automatisation also of chemical dosing,
sampling and monitoring.
7
Energy, Chemistry, Pulp and Paper.
There is no fire without smoke,
regardless of the source - oil, coal,
peat, organics. Wet gas-cleaning
will produce water effluents
similar to the previously described
metallurgical processes.
Water used for heat-transfer is
subject to strict demands in
quality. Contamination
by
corrosives from the pipe lines has
to be balanced by removal in
closed systems.
Solids, by-products or residues,
may be processed and re-utilized
as an integrated part of the
chemical process, or as a raw
material source, exploiting a waste
heap.
8
Condensates from waste residue
burning represents the worst case of
conta-mination with toxins such as
mercury, cadmium, dioxins, aromatic
hydrocarbons. By chemical pretreatment, clarification, filtration and
adsorption, these contaminants are
brought down to drinking water levels.
s
Metso Inclined Plate Settlers for
treatment of 800 m3/h of bottom ash
cooling water in a coal fired power
station. Metso thickeners, filters and
pumps are also used for gypsum
separation in FGD-plants.
s
s
Energy, Chemistry, Pulp and Paper
The SALA-HGMF ® , high gradient
magnetic filter, here in a nuclear power
plant, cleans e.g. boiler feed water,
condensates in thermal power systems
and district heating water at
unmatched filtrer rates.
Magnetite removal is close to 100%
even at submicron particle sizes. Total
iron removal is typically 90-95%. It also
removes substantial amounts of
copper.
It operates at much higher
temperatures than any other filter
system. It is also insensible to flow
variations and permits heavily
contaminated condensates. This
means increased boiler availability and
substantial energy savings.
Fea
tur
es
eatur
tures
• Extreme filtration rate
• No moving parts
• Long duty time - over 24 h between
automatic rinse
• Low power consumption
• High operating temperatures
B enefits
• Compact
• Reliable
• Low maintenance
• High availability
s
Metso Belt Drum Filter with cake wash
for recovery of magnesium oxide in a
pulp and paper industry. Also used for
fiber/clay and bark/sand dewatering.
s
Cleaning of solids from a landfill,
heavily contaminated by sulphur and
sulphuric compounds. The treatment
involves crushing, grinding, thermal
oxidation, flotation and dewatering. All
equipment is covered and ventilated
for odour control. Separated sulphur is
reclaimed. Purified soil is returned to
landfill. The flowsheet wasworked out
in close cooperation with the client.
Metso demonstrated the process in
laboratory and pilot test work,
engineered the plant, delivered the
equipment and stood responsible for
process guarantees.
9
Minerals Processing
Our ranges: Grinding Mills
Flotation Machines
Reactor Cell Systems
DR Flotation Machines
Flotation Columns
Classifiers
Spiral Classifier
Agitators
Mixers
Magnetic Separators
Low Intensity Magnetic
Separators
High Gradient Magnetic
Separators
Sedimentation Equipment
Inclined Plate Settlers
Thickeners & Clarifiers
Spiral Dewaterers
Metso Minerals (Brasil) Ltda.
Av. Independéncia, 2.500 Éden
18087-050 Sorocaba
SP
Brazil
Phone: +55 15 219 1300
Fax:
+55 15 219 1699
Metso Minerals (Chile) SA
Avda Vitacura 4380, 5th floor
Vitacura, Santiago
Chile
Phone: +56 2 3702000
Fax:
+56 2 3702039
Filtration Equipment
Vertical Plate Pressure
Filters
Tube Presses
Metso Minerals Industries Inc.
P.O. Box 15312, York
Pennsylvania, 17405-7312
USA
Phone: +1 717 843 8671
Fax:
+1 717 845 5154
Metso Minerals (Sala) AB
SE-733 25 Sala
Sweden
Phone: +46 224 570 00
Fax:
+46 224 169 50
Metso Minerals Canada Inc.
1197 Ballantry Road
Oakville, ON L6H 5M7
Canada
Phone: +1 905 337 8811
Fax:
+1 905 337 8827
Metso Minerals (UK) Ltd
Stocks House
North Street
Leatherhead, Surrey KT22 7AX
United Kingdom
Phone: +44 1372 81 43 00
Fax:
+44 1372 81 43 05
Metso Minerals (Johannesburg) (Pty) Ltd
Private Bag X2006
Isando, Johannesburg, 1600
South Africa
Phone: +27 11 397 5090
Fax:
+27 11 397 5826
Metso Minerals Asia Pacific
Locked Bag 10,
Blacktown BC, NSW 2148
Australia
Phone: +61 2 8825 1600
Fax:
+61 2 8825 1799
www.metsominerals.com
E-mail: [email protected]
Subject to alteration without prior notice
Processbaksida.indd 1
Brochure No. 1223-02-06-MPR/Sala - English
© 2006 Metso Minerals
Printed in Sweden
2006-02-24 08:55:51