Cyanide Destruction – WAD, FREE, SCN and TOTAL

One of the most important chemicals in the Gold Leaching Process is Cyanide. Cyanide acts as a complexant that reacts with the Gold to create a unique complex in the water. The main byproduct of the process is a family of Cyanide contaminants that are related to Free Cyanide (CN-Free), Weak Acid Dissociation (CN-WAD), Strong Acid Dissociation (CN-SAD) and the SUM of those species which is the CN-Total. The CN levels in the different regulation can range between 0.05 to 0.2ppm and can reach even higher levels for the WAD and the TOTAL types of cyanide.

The patented electrolytic process is based on the known total oxidation pathways of the Cyanide CO2 and N2. P2W plans, designs and constructs a unique structure of reactors – high performance electrodes with high surface area and an appropriate electrical current required for the oxidation process.

The Cyanide oxidation process occurs and takes place inside the reactor, on the electrode surface and within the flowing water media. The reactors contain several individual electrolytic cells that combine modular cathodes and anodes of various types. These anodes and cathodes are defined according to the type and the level of the contaminants in the wastewater.

The electrolytic reactor unit includes a set of coated commercial electrodes. The electrodes are configured in an alternating manner, such that each cell is different from the one that is next to it. Parts of the inner electrolytic cells are working in series and parts of them are working in parallel. When connected to an external power source, the anode material will electro-chemically corrode due to oxidation, while the cathode will be subjected to passivization. For this reason we use bi-polar electrodes that automatically change polarity and totally eliminate the passivization problems. The current densities are controlled by a central system that controls the current and the volt according to the in-fluent parameters of the water (mainly conductivity) and is automatically adjusting electrical parameters according to changes in water quality.

Common Cyanide destruction system is combined with the following components:

• A pretreatment unit – in order to remove any interference to the electrolytic process such as organic matters, suspended solids and may include any other pretreatment process that is required for the process.  This unit usually combines a settler and a buffer tank that are designed according to the quality of the feed water.

• An electrolytic reactors system – based on P2W’s patented technology! This system includes the number of electrolytic reactors, the electrodes types and numbers, the electrical connections and other important parameters that vary according to the type of project.

• Post treatment components are designed according to the client’s needs and may include Settlers, Sand filtration, Micro Filtration, Reverse Osmosis (only optional) or other water treatment processes. The plant’s specification varies according to the basics of the design, the client’s needs and the requirements of the regulation.

The uniqueness of P2W’s technology is based on the Electrochemical Oxidation Process that doesn’t involve any chemicals. The average power consumption per cube is around 0.5-1.0 Kw and the period between the replacement of electrodes ranges between 12 to 24 months.