Dynamic heat balance modelling of industrial bioleaching plant: Influence of both environment and operating conditions and heat management improvement

Abstract

A heat balance model was developed for bioleaching processes in stirred tank reactors, based on mechanistic and semi-empirical models to describe the contribution of each heat transfer phenomena. It was validated based on the cooling power required for two industrial case studies at typical bioleaching temperature of 40 °C and sulfide concentrations of 0.80 and 0.52 %. It was then tested on various scenarios. At high sulfide concentration, heat transfer from pulp addition and aeration was more significant than environmental transfers. This was validated using environmental ranges of values (temperature, wind speed, relative humidity, cloud cover) from either subarctic or equatorial climates. In the case of Finland, 12 % more power was predicted in summer than in winter. Regarding the number of primary tanks, one tank may be removed on the KCC-cascade system to save investments, by accepting a 4 % reduction in conversion rate. Finally, heat loss due to environmental conditions increased as the pyrite concentration decreased, passing from only 12 % with a concentration of 80 to 53 % with a concentration of 10 %. Control of the feeding pulp temperature could reduce the use of heat exchangers, and even eliminate them at low sulphide concentrations.