A tailings pond is a temporary storage area for the leftover by-product materials from oil sands, shale gas and coal ash operations, and is often a discontinued mine pit that has been re-engineered with a dam and dyke system. The contents of the pond is a slurry, with large volumes of water, sand, clay, residual hydrocarbons, heavy metals, naphtha diluents and naphthenic acids, which are known as tailings. The various materials settle to different depths, but they can all be dredged and dried to reduce their volume and eliminate moisture.
Advances in technology have allowed lower grade ores to be exploited, and in turn, this generates higher volumes of waste that require safe storage. In addition, environmental regulations also advance, which places more stringent requirements on the mining industry, particularly with regard to tailings storage practices. Tailings disposal is one of the most important sources of environmental impact for many mining operations.
A Renneburg Rotary Dryer from Heyl & Patterson can be the final step toward controlling the disposal costs of these tailings. Using proven designs and our pilot plant testing and development capabilities, our drying technology can reduce tailing volume by as much as 80%, reduce moisture content to less than 1%, reduce transportation costs, reduce landfill and disposal costs, make tailings easier to handle, recover any additional minerals and produce a usable product.
The Rotary Dryer is an industrial workhorse, engineered to accept bulk quantities of wet sludges and slurries in a variety of sizes, shapes and consistencies and provide a uniformly dried product. This versatility rests in the fact that thorough pre-conditioning of the feed stock is not always necessary. The Rotary Dryer can accept swings in feed moisture and particle size without system upset or shutdown. These features make for an extremely flexible machine which can be adjusted to changing conditions.
Rotary Dryers can operate using direct or indirect heat sources, such as natural gas, propane, oil or steam. Various feeding system options including extruders, delumpers, agitators, screws or augers can be utilized to optimize the material's surface area and promote more efficient drying. Diverse materials of construction can be made to suit any corrosive characteristics of the tailings or temperature requirements of the drying conditions. Processing variables such as shell speed, slope, temperature and air flow can all be changed while in operation to accommodate varying feed conditions, and the dryers can be equipped with dust collection equipment, baggers, thermal oxidizers and heat recovery options. Most types of hazardous and non-hazardous materials can be processed.
Once processed, tailings can be reused as a new supply of raw materials for the construction of highways, bridges and even commercial buildings. In comparison, the production of Portland cement requires great amounts of energy to reach the extremely temperatures needed, while emitting large amounts of greenhouse gases. This could potentially solve two issues -- it reduces the amount of tailings and also reduces the need for conventional raw materials.
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