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84/13/1995 08:37 <br />~_ <br />303-762-0390 <br />Mine aide treatment: <br />CDH W~CD W~CC <br />e <br />WASTEWATER TREATMENT SYSTEM <br />PAGE 03 <br />The mine side treats wastewater before it is discharged into waters <br />of the State. The wastewater comes from two source:: mine <br />dewatering, and domestic wastewater. <br />The mine water ie developed ae a result of underground mining. The <br />water is collected in the underground drifts, and sent to one of <br />two collection settlers located on the 7500 level. The collected <br />water 1s then pumped to the mine water treatment system, also <br />located on the 7500 level. A chemical precipitation process is <br />used to remove dissolved metals from the water. <br />The treatment system uses a presently available drift on the 7500 <br />level for clarification. This location for the system is not <br />considered permanent in nature as it will have to be relocated as <br />the mine development approachQe the area. The system will be <br />relocated in total to the best available drift. Under the <br />production scenario envisioned by the current mine plan, relocation <br />will occur in 2005 and will serve the remaining life of tk~e mine. <br />The treatment process is similar to many otheY wastewater treatment <br />systems and involves raising the pH of the mine water uainc~ sodium <br />hydroxide (or equivalent). The increased pH causes di.seolved <br />metals to precipitate out of solution. To help increase the rate <br />of precipitation, a chemical floeul~nt (Nalco 9806 or equivalent) <br />is also added to the water. Scale inhibitor chemical (Nalco 9714 <br />or equivalent) is also added at various sites. <br />The precipitate generated by this process is conveyed to er.;haueted <br />mine workings or to the Mill site for processing. After treatment, <br />the effluent is sent to the #2 shaft for removal to the sL~rface. <br />The removal process involves two pump stations: one at the 7500 <br />level, and another at the 8100 level. Primary and back-tip pumps <br />are located at both levels. The 7500 #2 shaft settler also <br />collects water from the haulage tunnel. <br />Once on the surface, the water flows to a flume house which serve e, <br />ae a back-up water treatment system. Caustic and flocculent can be <br />added at this point if the primary underground system is a}sut-down <br />or does not perform to specification. Precipitate ie comreyed to <br />exhausted mine workings or to the Mill site for processing. In the <br />winter some of the water ie diverted to a heat recovery circuit <br />that ie used to transfer water heat to the air used to ventilate <br />