Design of solar pond for water preheating used in the copper cathodes washing at a mining operation at Sierra Gorda, Chile

Abstract

The Chilean copper industry is increasingly dependent on coal-generated electricity and diesel fuel for high altitude mining operations. The associated greenhouse gas emission expansion needs to be moderated, moving away from polluting imported energy sources. As an option, solar thermal energy is breaking through in mining processes, and several companies plan to evaluate the application of ponds among potential technologies. In this work, we propose the studied the performance of solar ponds to preheat water to wash the copper cathodes in a mine located in Sierra Gorda aiming to reduce fuel consumption and combustion emissions. The outcome was a dual array of solar ponds with an effective collecting area of 23 240 m 2 and a 1.8 m thick density gradient to prevent heat convection. The ponds could deliver up to 12 300 MW h/year on site, reducing the annual diesel demand by 77% with a collecting efficiency of 24%, avoiding 3300 tonnes of CO 2 , thus reducing the cost of the thermal kilowatt-hour by 37%. Future work may include the construction of an instrumented pilot pond and three-dimensional modeling. V C 2013 AIP Publishing LLC.

Solar water heating system and photovoltaic floating cover to reduce evaporation: Experimental results and modeling

“…In copper mining in particular there is a significant potential for using solar energy to heat solutions in electro-winning and for washing copper cathodes [3]. In order to improve the leaching efficiency of sulfide minerals, a high temperature is required to improve the mineral process like leaching because the extraction increases with the temperature [4].…”

Constructal design of salt-gradient solar pond fields

“…Furthermore, a minimum depth of this zone is required to prevent erosion of the NCZ when withdrawing heat . For all these reasons, we used a fixed LCZ thickness of 1.1 m as suggested by Garrido and Vergara . Note that the model assumes that all radiation that reaches NCZ–LCZ interface is absorbed in the LCZ fluid.…”

“…We used a total land area of 23 200 m 2 (2.3 ha) for the SGSP field and a total mass flow rate of 6 kg/s. These parameters are the same than those used by Garrido and Vergara . In terms of water production, and based on the information provided by the SISS , a mass flow rate of 6 kg/s represents the water consumption of ~3000 inhabitants in the city of Copiapó (~2% of the population of the city).…”

“…The LCZ is a layer of fluid with high levels of temperature and salinity. The solar radiation that reaches the LCZ warms the hot brine and allows storing significant amounts of energy , which can be used in low‐temperature applications, such as building heating , thermal desalination , industrial heat process , among other applications .…”

“…Therefore, the stored energy was lost, and no energy was stored or produced while the system was under repair. Some works have proposed to build more than one SGSP to allow energy collection and storage in case one pond is not working properly , or for another purposes . However, the design of a solar pond field has never been analyzed in terms of number of solar ponds that must be built to maximize the useful energy, or the most convenient way to connect the ponds.…”