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Step 4: Comparative assessment of alternative
technologies
a. Identify and briefly describe alternatives to the technology being
assessed.
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Alternative
|
Description
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Option 1.
Gas fired rotary furnace and refining |
Pre-treatment as for proposed technology intervention; battery scrap, lead
metal scrap, waste scrap and flue dust are charged to a gas-fired rotary
furnace; coke or coal, steel scrap and sodium carbonate added; slag produced
will be reprocessed; gases and dusts will be passed through secondary
after-burner and bag house filters; refining will involve dedrossing and
addition of metals to produce lead alloys, and then casting of the ingots;
integral hoods used to contain fugitive emissions.
As a more environmentally friendly operation some companies are now
adopting the use of calcium salts to replace the sodium saltsin order to produce
a non leachable slag that can be disposed of in a landfill site or used as
hardcore for roads.
|
Option 2.
Gas fired blast furnace and refining |
Process is essentially the same as Option 1, apart from
substitution of a blast furnace for the rotary furnace. A blast furnace is a
vertical furnace that consists of a refractory lined crucible with a vertical
cylinder fixed to the top. Fluxing agents would be lime based to produce a hard
non leachable disposable slag. The bast furnace would also use natural gas. |
|
Option 3.
Diesel fuelled reverbatory furnace and gas fired blast furnace in
combination, and refining
|
Process is essentially the same as Option 2, but a
reverbatory furnace would be used in combination with the blast furnace. A
reverbatory furnace is a rectangular refractory lined furnace operated on a
continuous basis. The roof of the furnace is designed to "reverberate"
heat to the molten bath. The furnace produces alow antimonial lead bullion and a
slag with high antimonial lead content and few other impuritiest; this slag
would be smelted in the adjacent blast furnace. The reberbatory furnace will use
diesel fuel; the blast furnace will use natural gas. |
|
Option 4.
Used lead acid batteries will be collected and exported.
|
Used lead acid batteries will be collected using both the formal and
informal sectors; initially the batteries will be placed on pallets, wrapped and
stored at provincial collection centres, before being transported to and stored
at Port Udanax. The batteries will be shipped overseas, in containers. All new
batteries used in Udanax would have to be imported, as at present.
There may be export restrictions for the shipment of used batteries
containing acid and the electrolyte may need to be drained prior to shipping.
Shipments need to comply with the PIC procedure under the Basel Convention.
|
b. Evaluate the degree to which each alternative satisfies the goals that
must be achieved by the technology intervention (see Step 1d).
c. For each alternative technology, compare its potential impacts and
economic viability, relative to the technology being assessed (see Worksheet B
for additional guidance)
Option 1: Gas fired rotary furnace and refining
Option 2: Diesel fuelled reverbatory furnace and gas
fired blast furnace in combination, and refining
Option 3: Diesel fuelled reverbatory furnace and gas fired
blast furnace in combination, and refining
Option 4: Used lead acid batteries will be collected
and exported
d. Conclusions regarding alternative technology interventions
i) Elaborate the information gaps and uncertainties identified in Step 4c.
|
Option 1 - gaps and uncertainties:
Little information on likely impacts of technology on the local environment;
environmental pressures dependent on level of pollution control; high
uncertainty regarding compliance with strengthened environmental regulations
that may be introduced; more certainty with economic performance due to greater
experience with the technology.
Option 2 - gaps and uncertainties:
As for Option 1.
Option3 - gaps and uncertainties:
As for Option 1.
Option 4 - gaps and uncertainties:
Ongoing actions of individuals in the informal sector are unclear;
considerable uncertainty as ability to export batteries requires both private
sector participation plus compliance with international legal agreements;
implications of ongoing need to import new batteries also unclear.
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ii) Is any option a viable alternative?
 |
No - complete Step 5, considering only the proposed technology
intervention |
 |
Yes, and the present assessment is adequate - complete Step 5 |
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Yes, but need to complete Steps 1 to 4 for the option |
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Too many uncertainties and information gaps - need to repeat
Steps 1 to 4, as appropriate |
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