heavy metals a topic of concern in south african foundry waste sand
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Heavy Metals a Topic Of Concern in South African Foundry Waste Sand. Farai Banganayi University of Johannesburg Farouk Varachia University of Johannesburg Metal Casting Technology Station (MCTS). Presentation Lay Out. Introduction Background Preliminary Results Discussion - PowerPoint PPT PresentationTRANSCRIPT
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Farai Banganayi University of Johannesburg Farouk Varachia University of Johannesburg
Metal Casting Technology Station (MCTS)
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Presentation Lay OutIntroductionBackgroundPreliminary Results Discussion Conclusion
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Introduction MAP OF AFRICA L0cation
The University of Johannesburg is in South Africa
The Economic hub of Southern Africa
MCTS is located in a 20km radius to the Eastrand Area were most foundries are located
Positioned to service the foundries
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What we do
Effect technology and skills transfer to local foundries
Present short course training in foundry technology Provide sand and metallurgical testing services Provide assistance with trouble shooting in
foundries Place students in foundries Host exhibitions ,seminars and workshops Research and development in the foundry industry
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Background Heavy metals definition is inconsistent and
therefore necessary to deal with metals specified in regulations
Environmental issues concerning use of hazardous materials important in design and casting life cycle management
Environmental issues become of more concern at sand waste disposal (bulk)
There are about 180 foundries in South AfricaMajor raw material is scrap ferrous and non
ferrous
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continuedMetal scrap is the source of heavy metalsPrevalence due to scrap being acquired from
old obsolete infrastructure Old obsolete infrastructure and components
had little emphasis on environmentally friendly designs
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Scrap components as a major source of heavy metalsSource Heavy metals contained
Electrical components Cadmium,copper,zinc,lead and tin
Bearings Copper, lead and tin
Galvanised metal Mostly zinc or aluminium
Plated components Nickel ,cadmium, chromium or tin
Painted or coated cadmium,cobalt,copper,nickel lead and tin
Vehicle fuel systems and rims Mostly lead
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Sand metal interactions in the foundryPouring- sand burn on /that need to be fettledMelting –Metallic oxide emissions deposit
anywhere within the vicinity of the foundry
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Heavy metals’ potential entrance into the ecosystem
Foundry Waste Sand
water Plants
Humans and Animals
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Effects on Microbes and plantsHeavy metals cause decreased microbial
activity Decreased plant growth when they cannot be
accumulated in plant biomass
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Effects on Humans Heavy Metal Effects
Arsenic blood, kidneys, and central nervous, digestive, and skin systems. Chronic exposure leads to the development of skin and liver cancer
Cadmium liver, placenta, kidneys, lungs, brain, and bones
Chromium VI Carcinogenic
Mercury Target organs are the brain and kidneys
Lead Target organs are the bones, brain, blood, kidneys, and thyroid gland
Antimony irritation of the eyes and skin, lung disease and heart problems
Selenium include hair and fingernail , kidney and liver tissue, damage to circulatory tissue, and nervous system.
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Heavy Metal threshold limits and Risk classification in South Africa
Limits set on toxicity and bioavailabilitySouth Africa adapted the Environment
European Commission (EEC) procedure and uses the Toxicity Characteristic Leaching Procedure (TCLP) to support or affirm the EEC.
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Preliminary Heavy Metal Assessment in some South African foundries. Green sand wastes TCLP extracts in mg/l
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South African foundry Green sand wastesTCLP extracts in mg/l
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South African foundry Green sand wastesTCLP extracts in mg/l
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DiscussionEnvironmental protection Agency (EPA)
regulatory limits in mg/l was as follows As 5.0 mg/l, Ba 100 mg/l, Cd 1.0 mg/l , Pb 5.0mg/l ,Hg 0.2mg/l, Se 1.0mg /l, Ag 5.0mg /l (1998)
Lead most likely of concern in South Africa below EPA limits
Siddique et al. (2010) High Lead India(Dungan and Dees, 2009) High Lead USA
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Disposal costSouth African foundries problem area is the
disposal cost In the United Kingdom foundry waste sand,
qualifies under the lower rate tax, which is £2.50 =$4.10 usd per tonne (FTJ, 2011). In South Africa general waste disposal is about R250=$34.00 usd per tonne
Of which at the moment some foundry sands will be considered as potentially hazardous depending on risk
This affects long term profitability of the foundry business
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South Africa Foundry Industry’s possible mitigation and remediation strategies
Development of new environmentally friendly alloys
Design of new effective extraction systemsCareful selection of scrapDevelopment and proper use of well
documented Environmental Management Plans
Produce castings that require less fettling
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Possible Remediation
Development of a foundry waste sand bankPhytoextraction
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Potential alternative uses
Agriculture soilsAsphalt mixesEmbankments Bricks Reconstruction Development Programme
houses (RDP)Landfills Advantage south Africa has a
vibrant,agriculture,construction and mining industry for reuse
Research in India Siddique et al. (2011) Used Foundry sand for concrete and construction materials. There are similar initiatives in Brazil -Voge
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Conclusion Need for collaboration between
foundries,agriculture,environmental,construction industries and government departments.
Need to come up with scientific data and facts to convince environmental authorities that foundry waste sand is very low risk like in some states in the USA
Reuse reduces costs to the foundry and potential user so it saves energy
Reuse will ensure sustainability.Reuse can create opportunities for SME
creation.which is much needed in developing countries
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