Resumo

ZAMORA ECHENIQUE, Gerardo; MAMANI ALVAREZ, Melissa  e  TRUJILLO LUNARIO, Elvis. Propuesta técnica, económica y ambiental para el tratamiento de las aguas ácidas de la mina Huanuni mediante drenes anóxicos calizos y precipitación con cal en interior mina. REV. MAMYM [online]. 2018, n.4, pp.3-17. ISSN 2519-5352.

The Huanuni Mining Company is located in the Pantaleón Dalence, province of the Department of Oruro -Bolivia, belonging to the municipality of Huanuni and located 42 km from the city of Oruro, approximately betweenthe coordinates 66 ° 45' of Longitude East and 18 ° 15 'of Latitude South. The lack of water is severe in the Huanuni Mining Company, and great concern has been generated to supply the new Lucianita plant, which will operate with a capacity of 3000 T / day; therefore, it will be necessary to treat acid mine waters in order that the total flow of 60 L / sec can be used in said ore beneficiation plant. The object of the present research work is limited to making a technical, economic and environmental proposal for the treatment of the water resources of the Huanuni Mining Company by passing them through anoxic calcareous drains installed in the interior of the mine, as an alternative to the proposal of the company "Accidental Association AA MINAS" of conventional treatment with lime; especially, because although said proposal complies with the discharge of the effluent from pH 6 to 8 suitable for industrial use, the sludge generated in the process has no defined storage site and its transport to 20% solids to the new dam queues would be too onerous because of the high energy consumption it would represent; and in addition, in contact with the sulfuric tails, it would generate the formation of CaSO4 that would hinder its recirculation. From the technical point of view, for the implementation of the proposal, it was calculated that to treat 60 liters per second of acidic waters through anoxic limestone drains inside the mine, also considering a residence time of 15 hours and 20 years of operation of the drains, 17,077.29 tons of limestone are required. The Anoxic Limestone Drein (ALD) will be located in the interior of the mine, on the entrance ramp to the lower levels, requiring an extension of the existing chambers 4 and 5 to reach the dimensions of 3.5 m high, 20 m wide and 100 mlong; and 3.5 mhigh; 17 mwide and 88 mlong, respectively. The discharge effluent from the ALD will be subjected to a lime precipitation process also in the interior of the mine; for this, a lime slurry preparation reactor of 2.5 m high and a diameter of 1 m will be required. The lime slurry will be sent by pumping to a settler of the lamella type, also implemented in the interior of the mine and with dimensions of 3.5 m high, 8 m wide and 7 m long, located in a dead gallery already existing that will allow the separation of the overflow or clear water already treated that will be pumped by the current pumping system to the surface; and on the other, the sludge from the process will be pumped to the free pits for storage without environmental problems. From the economic point of view, the implementation of the proposed treatment of the acid waters of the Huanuni mine by ALD and Precipitation with Cal requires an investment of 2.31 million US dollars. Comparatively, with the conventional process of neutralization - precipitation with lime, the treatment of 60 liters per second of the acid waters of the Huanuni Mining Company requires 30.69 tons of lime / day; and 311.66 tons of sludge / day would be formed; In addition, the sludge formed by this process, "are not chemically stable" and its management will cause the "redissolution of heavy metals". In addition, this method of treatment implies a cost for the use of lime of 6. 2 million US $ / year. That is to say, for 20 years of operation, about 124.44 million dollars will be spent. While, with the process of Anoxic Drains and Precipitation with lime in the proposed mine interior, only 132.87 tons of sludge / day would be generated; those that are also "chemically stable"; since, and they are not hydroxides, but hydroxylated complexes, and they will be disposed without environmental risks in 11 empty rajas per year in inner mine. Therefore, the treatment of the acid waters of the Huanuni mining company by means of Anoxic Drains and Precipitation with lime in the interior of the mine, is a technically viable alternative, economically cheaper (allowing a saving of 121.91 million dollars in 20 years of operation) and environmentally more favorable and without environmental risk with respect to conventional treatment by neutralization - precipitation with lime.

Palavras-chave : Anoxic Limestone Drein; ALD; acid mine waters; treatment; Hunanuni Mine.

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