At the same time they are chemical plants handling dangerous chemicals and have to ensure safety to the miners as well as the environment. High yields and low operating costs are required to ensure profitability. Our HYPROX® 600 high quality hydrogen peroxide (60% concentration, other concentrations available as well) from our global production network help to reach these goals.
In gold production hydrogen peroxide can serve two functions: The most common method used nowadays is the cyanidation process, which involves the leaching of gold containing ores by dilute aqueous cyanide solutions. This requires pH adjustment, mostly by lime, and oxygen for the redox reaction to occur. Depending on the leaching conditions, overall concentration of suspended ore as well as concentration of the oxygen consumers in the ore, hydrogen peroxide can be added to increase the oxygen availability and dissolved oxygen in the system and to promote deeper leaching by direct oxidation. This is generally called Peroxide Assisted Leach (PAL) and helps to increase yield and profitability.
In most mines and depending on the environmental situation hydrogen peroxide is used for Effluent Treatment. It removes remaining cyanides from waste streams, such as discharge water or tailing slurries. Cyanide removal from process water may also be required if flotation takes place on site. The cyanide removal occurs via oxidation in a single step, without the formation of toxic intermediates or final reaction products.
Similar to the PAL process in gold mining hydrogen peroxide can serve as an important process agent for many other metals. The most prominent example is Uranium Mining. In nature uranium occurs in the form of tetravalent or hexavalent oxide minerals (uraninite or pitchblende). Tetravalent uranium has, however, a very low solubility in both acidic or alkaline media. Thus, to achieve an economic uranium recovery, oxidation to the much more soluble hexavalent state is of great importance. Trivalent iron compounds are commonly used to increase uranium's oxidation state. Hydrogen peroxide is applied for regeneration of the active Fe(III) ions in the eluent.
Together with distribution and logistic partners in most parts of the world Evonik has set-up a network to serve mines even in remote locations. This ensures short lead times, reliable supply and experts handling the sometimes tricky export and import processes.
Please ask us for a proposal and an offer for your specific mining sites, wherever these might be.