2 The following table gives some results from experiments in which the current efficiency
of zinc deposition in an electrowinning operation was determined at various current
densities (amperes per square meter of cathode surface area). The cathode area at
the plant is 10,000 m2.
Current Density Cell Voltage Current Efficiency
(A/m2) (V) (%)
300 1.5 92
400 2.3 88
500 3 82
600 3.9 72
700 4.8 52
800 5.8 10
To investigate the tradeoff between increased production rate (increased current
density) and cost please make a Table consisting of the following columns. Column 1
is the current density transferred from the Table above. For the other columns, please
provide a sample calculation below the Table.
a) Column 2 is the calculated production rate of Zn in kg/day (don't forget to take the
current efficiency into account).
b) Column 3 is the calculated energy consumed per day in units of kilowatt hours
(kWh). Please recall that a volt has units of joules/coulomb and an amphere has
units of coulombs/sec.
c) Column 4 is the energy consumed per kg Zn produced.
d) Column 5 is the cost of producing a kg of Zn. To perform this calculation, assume
that the cost of electricity is $0.06 per kWh and the plant costs $20,000 to run per
day (labor, heating, insurance, etc.).
e) Which production rate minimizes the cost of Zn production in dollars per kg?
Zinc deposition is investigated.