Technologies - EMEW Electrowinning Download The PDF
1: Electrowinning types 2: Value and Applications 3: Reduced Risks 4: Harvesting the Metal 5: FAQ 1 6: FAQ 2 7: FAQ 3

EMEW Electrowinning - Precious Metal Recovery / Metal Recovery

Based around the globally patented EMEW® Electrowinning cell, the technology has been demonstrated to achieve significantly enhanced performance over a wide range of flows and effluent conditions, and is now implemented in many mining and industrial settings around the world.

Conventional electrowinning involves placing an anode and cathode into a bath of slowly circulating or stagnant electrolyte. The metal ions eventually make their way to the cathode to be plated.

With EMEW® Electrowinning, the electrolyte is circulated rapidly past the anode and cathode at a higher flow rate, allowing for improvements in efficiency and the precious metal recovery / metal recovery.

EMEW Electrowinning Cell ®

1. Each EMEW® electrowinning cell comprises of a 6 or 8 inch pipe made of stainless steel or PVC. The cathode area in each cell is 0.5m² for the 6 inch cell, or 1m² for the 8 inch cell. The ANODE runs through the centre of the cell. The Inside surface of the pipe is the CATHODE.

2. There are two types of EMEW® electrowinning cell. One produces metal plate, the other produces metal powder. In the powder cell the Anode has a larger diameter and a smaller electrode gap.

EMEW Electrowinning Plate Cell ®

3. For plating cells a Starter Sheet, (usually made of stainless steel), is slid inside the body of the EMEW® electrowinning cell.The metal being recovered is plated onto this removable/reusable starter sheet when current is passed between the ANODE and the CATHODE.

EMEW Electrowinning Cell ®

4. The electrolyte is pumped through the cell from the bottom. Power is applied to the cell between the ANODE & CATHODE. Metal then begins to plate, or forms as powder, on the CATHODE.

EMEW is a world leading technology in the process of electrowinning. Through technical innovation, intelligent engineering and use of modern materials, EMEW has been developed as a hardware system which effectively ‘turbocharges’ an age old process. The result is a dramatic improvement in efficiency, significantly lowering cost and extension of potential uses well beyond its traditional marketplace.

EMEW Creates Value

The radical improvement in efficiency made possible through EMEW technology now allows our customers to complete precious metal recovery for metals previously not recovered or disposed to waste. The significant operating and capital cost benefits of the technology have altered the economies of scale for metal project development - creating viability where it may not previously have existed.

EMEW Enhances Value

Electrometals & the EMEW technology enhance value for its customers through a simple single step process for Precious Metal Recovery. In comparison with traditional methods, we offer:
  • Reduced capital cost of your precious metal recovery process
  • Reduced operating costs in a simplified flow sheet
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  • Accelerated return on capital
  • Improved product purity
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    Applications

    The application of the EMEW technology has been proven over a very wide range of applications - too many to reproduce in detail in this brochure. For more information about possible applications please contact us using details below.

    Broaden process options with EMEW Due to its inherent simplicity and efficiency, the EMEW technology allows more direct and versatile options in the field of precious metal recovery through:
  • Capability to process low metal concentration streams.
  • Higher productivity than conventional cells.
  • Efficiency over a wide range of metal concentration.
  • Higher tolerance of contaminants in solution.
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  • Capability of extracting a variety of metals.
  • Capability of selective electrowinning of metals.
  • Generally higher purity product.
  • Production of either metal cathode or powder.
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    Reduce Technical Risk with EMEW

    EMEW technology is:
  • Simple to operate.
  • Constructed with minimal moving parts.
  • Easy and inexpensive to maintain.
  • Delivered as a complete facility.
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  • Modular and portable.
  • Easy to expand or relocate.
  • Does not use reagents or chemicals.
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    EMEW is safer

    During conventional electrowinning of metals oxygen bubbles are produced at the electrodes. When these bubbles reach the surface they burst, liberating an aerosol of acid called mist, which can affect the health of operators, the environment and plant infrastructure. The International Agency for research into cancer (IARC) a respected international science group based in Europe, classified sulfuric acid mists as causing cancer in humans.

    EMEW provides as an inherent design characteristic complete elimination of the release of acid mist into the workplace. The EMEW technology capture ALL gases that can be generated and makes them available for collection and safe disposal or reuse. This feature of EMEW provides significant improvements to the working environment.

    The technology can be built into custom designs for specialised application in almost any configuration. Two standard models are currently offered:

    The EMEW plating cell

  • Current Density up to 1000 a/m2.
  • Product is a high quality solid cathode.
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  • Serial or parallel arrangements of 6” (150mm) diameter plating cells.
  • Only moving part is a process pump.
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    The EMEW powder cell

  • Current density up to 2000 a/m2
  • Product is an easily liberated metal powder.
  • Full PLC control provided.
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  • Harvesting process totally automated.
  • Serial or parallel arrangement of 8” (200mm) diameter plating cells.
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    Harvesting the Metal



    1.2.
    Powder cells are harvested automatically using a flush through methodology.
    This flush harvesting is controlled by a PLC and is fully automatic    		 Plating cells are harvested by removing the top and extracting the cathode.
    The starter sheet is then replaced and the process starts again.

    Frequently Asked Questions 1


    What is electrowinning ? Electrowinning is electrochemical Precious Metal Recovery / Metal Recovery from their dissolved state. It involves the application of electrical current between two electrodes immersed in a metal bearing solution (known as electrolyte). Under the correct conditions the dissolved metal will plate on to the negative electrode (cathode).

    Why does the EMEW® electrowinning cell out perform conventional electrowinning technology? The high performance of the EMEW® cell technology is achieved through a hydraulic mechanism which achieves higher rates of metal ion transport to a cathode than in a conventional electrowinning reactor. The essential difference is that the EMEW® cell is constructed from a pair of concentric tubular, rather than planar, electrodes. The ends of the assembly are fitted with plastic end caps, thus forming a closed chamber through which target solution can be pumped at high rate. The resulting high flow and efficient mixing result in 'forced' and continual supply of metal ions to the surface of the cathode.

    Which metals can EMEW® electrowinning recover? The EMEW® electrowinning cell is used for Precious Metal Recovery / Metal Recovery for a variety of metals including gold, silver, platinum, cadmium, cobalt, copper, nickel, tin, zinc, lead, manganese and many other metals.

    What is the cathode area of the EMEW® electrowinning cell? The 150mm plating cell has a cathode area of 0.5 M². The 200mm powder cell has a cathode area of 1.0 M².

    What is the production rate of an EMEW® electrowinning cell? This will vary depending on the metal being recovered and the solution characteristics, however in a typical sulphate solution, a single plating cell can produce up to 12 kg per day. A powder cell produce around 25 kg per day.

    What is the difference between the plating cell and the powder cell? The plating cell produces a coherent solid metal cathode that "plates" to the starter sheet inside the cell. It has a cathode area of 0.5 m2 and is typically used for concentrations above 1 g/l. The powder cell produces a powder deposit, which is harvested using a flushing process. It has a cathode area of 1.0 m2 and is typically used for concentrations below 1 g/l.

    Can the powder cell be used to recover metals at a higher concentration? Yes, through the use of a continuous grade circuit.

    Frequently Asked Questions 2


    Can the EMEW® electrowinning cell recover silver from a solution that contains high levels of copper? Yes. The EMEW® cell can selectively electrowin a specific metal in the presence of others, the order in which metals are removed from solution is determined by their position on the metal activities series.

    To what level can the EMEW® electrowinning cell recover metals? Again this does depend somewhat on the solution chemistry and the target metals. However in the case of gold the EMEW® cell has achieved a discharge level of 0.01 ppm and 0.1 ppm for copper.

    Does the EMEW electrowinning cell have any moving or rotating parts? No, the pump is the only moving part of the plant.

    What is the flow rate through each cell? Approximately 6000 liters per hour in the plating cell and 2000 litres per hour in the powder cell

    At what weight will the cathode require harvesting? Approximately 25 kg.

    How long does it take to harvest a single cell/cathode? About 1 to 2 minutes for plating cells. Powder cells are harvested automatically.

    Does the EMEW electrowinning cell release acid mist into the environment? During conventional electrowinning of metals (e.g. zinc, copper), oxygen bubbles are produced at the anodes. When these bubbles reach the surface they burst, liberating an aerosol of sulphuric acid called acid mist, which can affect the health of operators, the environment and plant infrastructure, The EMEW technology captures ALL gases that can be generated and makes them available for collection and safe disposal or reuse. This feature of EMEW provides significant improvements to the working environment.

    What is the anode made of? For low pH solutions the anode (DSA®) is made from a titanium tube that is coated with iridium oxide. For high pH solutions the anode is typically constructed of stainless steel.

    What is the life of the Anode? Electrometals use the world leading Dimensionally Stable Anode (DSA®) from the De Nora Group. In most cases the anode life is 4 to 6 years, at which point the anode may require recoating.

    Frequently Asked Questions 3


    What happens to the gases that are produced as part of the normal electrowinning process? The EMEW® electrowinning cell is a totally enclosed unit. All gases are captured in the top of each cell and can be vented as appropriate.

    Does the EMEW® cell alter the laws of electrochemistry? No, all the laws still apply

    How much cathode area is there in a commercial EMEW® plant? Depending on the application this can vary from only a few square centimeters to over 1000 M².

    Are there any commercial EMEW systems installed? Yes, we have commercial facilities in Asia, Africa, North America, South America and Europe.

    Is electrowinning a new process? No, electrowinning has been a commercial process for almost 100 years.

    How uniform in thickness is the copper cathode? Very uniform as the current distribution is very even

    How does the copper cathode quality differ to that of conventional EW? It will be higher purity as the EMEW process is less prone to contaminants