Sustainable Environment Management Practices in Small Scale

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Transcript Sustainable Environment Management Practices in Small Scale

Feasible Environmental Solutions for
Small Scale Secondary Lead Smelting
Industry Sector
Workshop on
Sustainable Environment Management Practices in
Small Scale
Secondary Lead Smelting Industry Sector
Dr. Amitava Bandopadhyay, Chief Scientist
CSIR-National Metallurgical Laboratory
Jamshedpur - 831 007
Kolkata : November 6, 2012
The Facts
•Industrial pollution is a critical public health threat on a par with
malaria and tuberculosis. While 125 million people around the world
are at risk from toxic pollutants, these causes of illness and death are
underestimated.
•The lack of investigation and quantification of the human health
impacts of contaminated site have left an often marginalized
population with few resources to address this growing problem. Sadly,
health impacts from environmental pollution often affect the most
vulnerable, especially children, within these already neglected
populations.
•The Blacksmith Institute – Green Cross Report recently identified the
10 most toxic industries responsible for the number of illnesses and
deaths – number one on the list is lead-acid battery recycling. The
world’s second most toxic industry is lead smelting, with mining and
ore processing ranked third.
Health Impacts of
Lead Poisoning
Based on methods
detailed by the World
Health Organization
(WHO), it has been
concluded that :
•Lead impairs the
neurological development
of children
•Lead also causes
cardiovascular disease in
adults
A Typical Lead Recycling Unit
 Pollution from Small Scale Lead Smelting
Causes Health Problems for Workers as Well as
Nearby Residents
 Often lead recycling occurs at uncontrolled or
poorly controlled facilities in the informal
economic sector, even at home, making lead
reprocessing itself a major problem in many
countries
The Technological Options,
Practices and Possible Solutions
Technological
Development and
Environmental Implications
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1850s Onwards [Abundant Resources,
Diverse Market,
Unrestricted Development &
No Concern for Environment]
DRIVER : Concern for Health & Safety
 1970-1990 [Industry & Government Focused on
Managing Pollutants]
DRIVER : Concern for High Cost
 1990 Onwards [Prevent or reduce pollution by
providing help to industry outside the
enforcement realm –
Era of Green Design]
Advantages of Secondary Processing
 Conservation of ore resources and fuels
 Lower energy consumption – 5% for Al, 6-10%
for lead, 2-5% for Mg, 20-25% for zinc and 30%
for Cu
 Solution to waste disposal problem
 Lower emission of noxious and green house
gases
 The outlook for recycling various from country to
country but each nation benefits in the long run.
Production and Uses of Lead
Principal application area of lead is Pb-acid
batteries – accounts for 60% of total
consumption. Other uses are – corrosion
resistance surfacing, radiation shielding,
cable sheathing, sound proofing, damp
proofing, ornamental work etc.
Total production in India : ~100000 tons
[~40,000 tons from secondary sector]
Sources of Lead Waste Generation
Sources of lead bearing wastes are : Used
lead acid batteries, rejected materials from
battery manufacturing industries, slag from
smelters and other lead bearing scrap
materials such as bottom dross from
galvanizing units, used lead anode sheets
from primary and secondary zinc
producing units using electrolytic methods,
lead scrap from printing press and lead
pipes etc.
BASIC ISSUES
 Pollution from metallurgical sectors create significant
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health hazards
Industrial processes are not designed keeping pollution
prevention and control as priority
Cost effective pollution control technologies are mostly
not available
Pollution prevention require substantial discipline from
industries – However, benefits are significant
Psychological obstacles for pollution prevention and
control
What is Recycling?
•
Recycling involves processing used materials into new
products to prevent waste of potentially useful materials, reduce
the consumption of fresh raw materials, reduce energy usage,
reduce air pollution and water pollution by reducing the need for
"conventional" waste disposal, and lower green house gas
emissions as compared to virgin production.
•
Recycling is a key component of modern waste reduction and
is the third component of the “Reduce, Reuse, Recycle" strategy.
Critical Issues in Recycling of
Lead Bearing Wastes
 The recycling of wastes is one of the most important components of
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the sustainable development process
Wastes are now regarded as unutilized resources
Significant efforts are required to recycle wastes irrespective of their
type and the source of generation
Recycling takes a greater dimension as treatment and disposal of
hazardous wastes take significant investment.
Recycling of lead bearing hazardous wastes results in conservation of
mineral resources and lesser mining resulting in lower environmental
pollution.
The recycling must be done using Environmentally Sound
Technologies (EST)
A large gap exists between actual generation and the amount that is
being recycled through EST
Developments in Traditional
Lead Waste Processing
 Use of non metallic constituents as fuel is
discouraged
 Primary issue in cleaner technology is separation
of all components and subsequent processing
 A sequence of crushing, screening/washing,
heavy media separation and flotation processes
are used for separation of components
 Pretreatment of battery paste to lead carbonate is
used now to avoid sulphur problems during
smelting
 Level of sophistication varies from place to place
Recycling of Lead Bearing Wastes
 The lead bearing wastes as specified in Schedule - 4 are
used in the production of lead ingots and lead alloy ingots
 The main steps involved are : smelting of the lead bearing
wastes after addition of fuel and flux, cooling and casting
of the molten lead into lead ingots.
 Alloys are produced by melting and refining of the lead
ingots after mixing with alloying elements.
Smelting is a thermal metallurgical processing operation in which the metal or matte
is separated in fused form from non-metallic materials or other undesired metals
with which it is associated.
Non-ferrous Wastes Covered Under HWM
Rules, 2008
Technological Options in
Lead Recycling
• Traditional
Mandir Bhatti Furnaces
•Blast Furnaces
•Rotary Furnaces
•Lead Sweat Furnaces
•Reverberatory furnaces
[More suitable for fine particles]
Typical Flowsheet of Lead Batteries
Scrap Processing Plant
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Figure : 1
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Features
A Mini Blast Furnace (Commonly know
as mandir bhatti or shahi bhatti) is a
simple time tested and widely used
system to produce secondary lead in India
and many other countries. It is the most
basic of all furnaces and production
system based on this technology has
certain distinct characteristics such as:
•Low project capital cost
•Low energy cost
•Easy to install
•Easy to operate and maintain
Typical Mini Blast
Furnace for Secondary
Processing of Lead
Features
The Rotary Melting Furnace is a very
flexible and universal equipment used for
recycling many non-ferrous metals. It is the
major lead production technology used in
India and many other countries for
Secondary Lead Production. A lead
production system based on this technology
has certain distinct characteristics such as:
•Equipment scalable for installing higher
capacities
•Recovers all lead in one production cycle
•Plates & powder from scrap battery as well
as slag from Mini Blast Furnace can be used
as raw material
•Requires addition of certain consumables
•Can be fired with various fuels
•Generates high pollution both as flue gases
& fugitive emissions
Typical Rotary Furnace for
Secondary Processing of
Lead
Typical Material Balance for
Secondary Processing of Lead Scrap
Source : APPCB Information Bulletin,
March 2001 (Publication 111)
Emissions and Waste Generation
in Secondary Lead Recycling
Source : APPCB Information Bulletin, March 2001
(Publication 111)
Typical Values of Pollutant Emissions
from Secondary Lead Smelters
Constituents
Concentration (mg/Nm3)
•Suspended
Particulate Matters
250
•SOx
60
•NOx
30
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Lead in Work Area : 0.15 mg/Nm3
Steps to Minimize Fugitive Emissions
in Secondary Lead Processing
 The design of the hood/fume collection system from the
smelting/refining operations should be capable of collecting the lead
emissions and their transfer to the control system(s)
 The storage of all the raw materials, intermediates and products
should be in covered area/shed having concrete floors and
mechanized equipment should be used to handle these materials as
far as possible.
 The floors in the loading area should be kept wet through sprinklers to
reduce the chances of lead particles/dust getting airborne.
 The movement of vehicles to the administrative/working/production
areas should ensure that only the trucks/vehicles involved in the
material handling / transportation reach the work areas, and their
tyres are washed before they leave these areas.
Pollution Prevention & Control
in Lead Recycling
 Use doghouse enclosures where appropriate; use hoods to
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collect fugitive emissions.
Mix strong acidic gases with weak ones to facilitate production
of sulfuric acid from sulfur oxides, thereby avoiding the
release of weak acidic gases.
Maximize the recovery of sulfur by operating the furnaces to
increase the SO2 content of the flue gas and by providing
efficient sulfur conversion. Use a double-contact, doubleabsorption process.
Desulfurize paste with caustic soda or soda ash to reduce SO2
emissions.
Use energy-efficient measures such as waste heat recovery
from process gases to reduce fuel usage and associated
emissions.
Pollution Prevention & Control in Lead
Recycling
 Recover acid, plastics, and other materials when handling
battery scrap in secondary lead production.
 Recycle condensates, rainwater, and excess process water
for washing, for dust control, for gas scrubbing, and for
other process applications where water quality is not of
particular concern.
 Give preference to natural gas over heavy fuel oil for use
as fuel and to coke with lower sulfur content.
 Use low-NOx burners.
 Give preference to fabric filters over wet scrubbers or wet
electrostatic precipitators (ESPs) for dust control. This
reduces secondary pollution.
Key Issues for Compliance
 Give preference to the flash-smelting process where appropriate.
 Choose oxygen enrichment processes that allow higher SO2
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concentrations in smelter gases to assist in sulfur recovery; use the
double-contact, double-absorption process.
Improve energy efficiency to reduce fuel usage and associated
emissions; use low-NOx burners; give preference to natural gas/LPG
as fuel.
Reduce air emissions of toxic metals to acceptable levels.
Maximize the recovery of dust and minimize fugitive emissions; use
hoods and doghouse enclosures.
Reduce effluent discharge by maximizing wastewater recycling.
Avoid contamination of groundwater and surface waters by leaching
of toxic metals from tailings, process residues, slag, and other wastes.
Looking Ahead :
Does Cleaner Production
Provides a Better Future
for Lead Smelting &
Recycling?
Cleaner Production (CP) in
Metallurgical Sector
 Cleaner Production (CP) is the
continuous application of a preventive
environmental strategy applied to
processes, products and services to
increase efficiency and reduce the risks
to humans and the environment.
 Cleaner Production is aimed at reducing
consumption of raw materials, energy
and pollution created during the
production processes through process
optimisation and development of newer
technologies.
What Cleaner Technology Tries to
Achieve?
Minimise amounts and hazards of
gaseous, liquid and solid wastes
Minimise accidental risks from
chemicals and processes
Minimise consumption of raw materials,
water and energy, and
Substitute chemicals and processes
less hazardous to human and ecological
health.
Cleaner Production (CP) in
Metallurgical Sector - Advantages
CP eliminates toxic raw materials
 It reduces the quantity of toxicity
of all emissions and wastes at
source
It reduces negative impacts along
the life cycle of a product, from
design to ultimate disposal.
Barriers to Cleaner Technology
Applications
Non-availability
of Technology : An off-the-shelf
cleaner technology which can be readily purchased
and installed, is not available.
Incompatibility : The cleaner technology that is
available may not be compatible in terms of existing
scale of operation, raw materials, process, products,
lay-out, legal requirements etc.
Economic Non-viability : There may be a technology
that may not be economically viable for the industry.
Other Non-technical Barriers : These include
problems arising out of socio-economic conditions,
psychological factors, administrative and union
problems, fixed mind-sets, lack of awareness, lack of
competition, unethical and/or illegal escape routes,
legal entanglements, lack of incentives as well as
punitive measures.
Characteristics of CP Systems
 Each system focuses on continuous
reduction in raw materials & energy
consumption
 The use of each system results in a series of
waste reduction measures : Minimization,
reuse, recovery and disposal
 Each system calls for an integrated
approach to design, manufacture, and use of
product. In addition to inputs and waste
materials, it looks into how products are
produced, disposed of and accounted for
 Each system, over the long-term, is cheaper
than conventional “End-of-pipe” technology
Technology Related Issues
 Process Development & Integration
 Economies of scale – Advantages & Disadvantages
 Can we break the general rule of economies of scale to make
smaller operation economically viable?
 Feasibility of integrated waste processing from multiple
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companies
Engineering Issues
It is a combination of may techniques rather than use of one
fundamental principle
More we push technology to its limits, engineering issues
become more complex
Industrial waste and materials recycling
Technology only creates a barrier in 10% cases
Waste materials is used to reduce waste handling cost rather
than saving in raw materials cost
Economy of recycling would improve if design value is utilised
Cleaner Technologies for
Secondary Lead Processing
 Alternative cleaner technologies couple environmental
requirements to the energy savings with substantial
reduction in cost compared to traditional processes
 More advanced processes e.g. USBM, RSR, EWS and
Placid are based on same philosophy:
 Conversion of insoluble PbSO4 and PbO2 into leachable
products
 Leaching by a suitable electrolyte to put lead (Pb) into
solution
 Lead electro-winning with a insoluble anode with oxygen
evolution
Concluding Remarks
 An attempt has been made to summarise environmentally
sound technologies (EST) for recycling of hazardous
wastes containing lead
 The scale of operation of recycling plants in India is small
or tiny as compared to that in advanced nations. Hence
implementation of sophisticated technology at small scale
of operation is not easy.
 There is an urgent need to evaluate cleaner technology
options in the Indian context and chalk out a plan for the
recycling industry.
 The evaluation process needs to concentrate not only on
the technical and environmental aspects but has to focus
on scale of operation and economic as well as societal
aspects.