HEAT FROM MINE WATER : An investigation of different methods to be able to retrieve heat from the water that is pumped up from the mines

Boliden Mineral AB - Boliden Mines is a company that carries out continuous improvement work in the energy and environmental area. During this degree project, the possibility of making use of waste heat from the mine water that is pumped out of the Renström mine was evaluated. The possibility of making use of the heat from the mine water is interesting as the water that is pumped up maintains a stable temperature between +8 degrees to +20 degrees. This provides a suitable heat source for heat pumps by extracting the heat using heat exchangers or collectors. The purpose of this thesis has been to investigate which type of solution between collectors and heat exchangers is technically and economically most advantageous. The cases reviewed are to either invest in components for the existing heat pump, which is located next to the collection basin, in the old treatment plant, or to invest in a new facility in connection with the fire dam. Reviews to determine alternative collectors and heat exchangers were carried out on a theoretical basis. The review was based on the fact that collectors and heat exchangers must be durable, easy to disassemble and easy to maintain. Through economic analyzes and discussion with various companies and suppliers, three different collectors and three different heat exchangers respectively were determined as possible solutions. Conclusions were extracted from these components for the various cases. The conclusion that can be drawn for the existing case of the existing heat pump located adjacent to the collection pond, the old treatment plant, is that an installation of two Geek kooil collectors is the most economically beneficial investment. The company also chose to invest in this option.For the case of a new facility in connection with the fire dam, the result is presented depending on the investment in the number of heat pumps, where the payback times vary between the different investment options. The payback time of the collectors and heat exchangers varies between 3 to 8 years depending on the number of heat pumps or collectors.Conclusion given from both the existing case and the case of a new plant gave that from the point of view of the collectors, the Geek kooil collector was the better option, both for the existing heat pump and for a new installation of one, two or three heat pumps. A Geek kooil collector gave an investment cost per kW between SEK 3813 and 2647/kW. For the heat exchangers, the plate heat exchanger from Alfa laval was determined to be the better option for a new installation of both one, two or three heat pumps. The plate heat exchanger from Alfa laval gave an investment per kW of SEK 360/kW, which is lower than the comparative alternatives