A combined pumping test and heat extraction/recirculation trial in an abandoned haematite ore mine shaft, Egremont, Cumbria, UK

Abstract

A pumping test at rates of up to 50 L s -1 was carried out in the 256 m-deep Florence Shaft of the Beckermet-Winscales-Florence haematite ore mine in Cumbria, UK, between 8th January and 25th March 2015. Drawdowns in mine water level did not exceed 4 m and the entire interconnected mine complex behaved as a single reservoir. Pumping did, however, induce drawdowns of around 1 m in the St. Bees Sandstone aquifer overlying the Carboniferous Limestone host rock. During a second phase of the pumping test, a proportion of the 11.3-12°C mine water was directed through a heat pump, which extracted up to 103 kW heat from the water and recirculated it back to the top of the shaft. Provided that an issue with elevated arsenic concentrations (20-30 lg L -1 ) can be resolved, the Florence mine could provide not only a valuable resource of high-quality water for industrial or even potable uses, it could also provide several hundred to several thousand kW of ground sourced heating and/or cooling, if a suitable demand can be identified. The ultimate constraint would be potential hydraulic impacts on the overlying St Bees Sandstone aquifer. The practice of recirculating thermally spent water in the Florence Shaft produced only a rather modest additional thermal benefit.

A Review of the Performance of Minewater Heating and Cooling Systems

“…No system has been commissioned at the shaft, due to lack of clearly identified heat demand, and pending the demonstration of acceptable environmental impact, safe water disposal and agreement between owning/operating parties. Dissolved iron did not occur in significant amounts in the pumped water and no scaling or clogging issues were noted [58].…”

“…Open shafts provide access to a large volume of water in the mine workings and are engineered to remain open indefinitely [27], which brings extended life to the source. Hybrid systems are also possible, where part of the pumped water flow is returned to the shaft, while part is "bled off" and discharged to a surface recipient [58].…”

Water from abandoned mines as a heat source: practical experiences of open- and closed-loop strategies, United Kingdom

“…The larger (103 kW) pilot scheme at Egremont (Banks et al 2017) also successfully operated for a short trial period. However, monitoring of temperatures during the Egremont trial suggested that the heat extractable by a pure standing column arrangement might be limited to no more than 100 W m −1 (or several tens of kW for a typical deep mine shaft of several 100 m depth).…”

“…Egremont (Banks et al 2017) is based on an ironstone (haematite) mine, while the rest are coal mines…”