Electrolysis & Electrowinning

Electrowinning Current Density, Production and Energy Calculator

This calculator converts your cell current and cathode area into current density, applies Faraday's law to give theoretical production, corrects it by current efficiency, and turns cell voltage into specific energy consumption per tonne of metal. It is a mass-balance tool for sizing a cell house or interpreting a bench cell — not a deposit-quality prediction, which depends on electrolyte flow, temperature and additives as well as on current density.

Inputs

Metal being deposited

Sets the electrochemical equivalent mass used in Faraday's law.

Cell currentA

Total current passing through the cell, as set on the rectifier. For a bench cell this is a few amps; for a production cell house it is thousands.

Cathode area per plate (one side immersed)m²

Wetted area of one face of a cathode. If your plate is immersed on both sides, enter the total wetted area of the plate.

Number of cathodes in the cell

Cathodes only — do not count the anodes.

Current efficiency%

Measured deposit mass divided by the theoretical mass. 88–95% is a common band for copper electrowinning; iron in the electrolyte and short circuits pull it down.

Cell voltageV

Total voltage across the cell. Measured across the busbars, it includes the decomposition potential, overpotentials, electrolyte ohmic drop and contact losses.

Deposition timeh

Time the current is applied — one cathode cycle, or the length of your bench test.

How to use it

Runs entirely in your browser — nothing you enter is sent anywhere. Defaults are typical lab/pilot values so you can see the arithmetic move; replace them with your own numbers before you rely on the result.

Results

Total cathode area —m²

Cathode current density —A/m²

Theoretical production —kg/h

Actual production —kg/h

Actual production —kg/day

Deposit per cathode per cycle —kg

Specific energy consumption —kWh/t

Cell power draw —kW

The results appear here and update as you type. Each result is followed by the conditions under which it holds.

Read the assumptions before you use a number. A sizing figure without its conditions is not a result — it is a guess with a decimal point. The assumptions listed below are part of this calculator's output, not small print.

How to use it

Fix the cathode area correctly
Count only the wetted cathode area that the current actually travels through. Including anodes, or counting both faces of a plate that is immersed on one side only, is the most common source of a wrong current density.
Divide current by area
Current density is total cell current divided by total cathode area. It is the number that governs deposit morphology, cell voltage and the acceptable impurity level in the electrolyte.
Apply Faraday's law
The theoretical mass follows from current, time and the electrochemical equivalent mass of the metal. No assumptions are needed here — it is stoichiometry.
Correct for current efficiency
Multiply by measured current efficiency. Determine it by weighing the actual deposit against the theoretical mass for the charge passed — that single measurement is the most useful diagnostic you can run on an electrowinning cell.
Convert voltage into energy
Specific energy is proportional to cell voltage and inversely proportional to current efficiency. Every part of the cell voltage above the decomposition potential is waste heat that has to be removed from the cell house.
Sanity-check against the operating band
Compare the current density with the range normally run for your metal and electrolyte. If it is far outside it, expect a deposit problem before an energy problem.

Formulas used

Total cathode area A = plate area × number of cathodes
Current density  CD = I / A                            [A/m²]
Theoretical mass  m = (I × t × M_eq) / F                [g]
   F = 96 485 C/mol ;  M_eq in g per mole of electrons
Actual mass = theoretical × current efficiency
Specific energy  W = V / (M_eq × CE) × 26 801     [kWh per tonne]
   factor 26 801 = 3 600 000 × 1000 / (96 485 × 1000) grouped for g and tonne
Cell power       = I × V                         [W]

Assumptions & applicability

★ Electrochemical parameters are given as engineering estimates only. Current density, current efficiency and cell voltage are all system-specific — they depend on electrolyte composition, temperature, circulation, additives and electrode spacing — and no single-point value should be treated as a specification.
Faraday's law is applied to a single-electron-transfer half reaction at 100% faradaic selectivity before the efficiency correction. Side reactions competing for the same current are lumped into the current efficiency you enter.
Current efficiency is taken as a measured input, not predicted. Iron cycling between anode and cathode, short circuits and dendritic growth all reduce it and none of them can be calculated from the data entered here.
Cell voltage is taken as measured across the busbars. The split between decomposition potential, overpotential, electrolyte ohmic drop and contact resistance is not modelled.
Specific energy is per tonne of metal deposited and excludes rectifier losses, cell house ventilation, and any heating or cooling of the electrolyte.
Deposit quality — smoothness, nodulation, adhesion and purity — is NOT predicted. It depends strongly on the same variables and must be established experimentally.

FAQ

What current density should I run for copper electrowinning?

Most copper tankhouses operate in the range of roughly 250 to 350 A/m², with some running higher. Treat that as a reference band rather than a target: the practical ceiling for a given electrolyte usually shows up first as rough, nodular or dendritic deposit, and the limit depends on electrolyte temperature, circulation rate, acid concentration and additive regime. Establish it in a bench cell with your own solution.

Why is my current efficiency lower than expected?

The usual causes, roughly in order of how often they appear: ferric iron in the electrolyte cycling between the electrodes without depositing metal; electrical short circuits through nodules or misaligned plates; low electrolyte temperature; and leakage current losses. Weighing the deposit and comparing it with the Faraday prediction tells you that you have a loss but not which one — measure the iron concentration first, as it is the most common single cause.

How much energy does electrowinning consume?

Copper electrowinning typically falls in the range of about 1,800 to 2,500 kWh per tonne of cathode, depending mainly on cell voltage and current efficiency. Since specific energy is proportional to voltage and inversely proportional to efficiency, the fastest route to lower energy cost is normally reducing the electrolyte ohmic drop — by shortening the electrode gap or improving conductivity — rather than pushing current density in either direction.