Efficiency of heap leaching of metals from raw ore taking into account the influence of climatic factors

This paper describes the methods of comprehensive generalization, analysis, and evaluation of practical experience and scientific achievements in the field of geotechnology and heap leaching (HL) of metals from raw ore on the daylight surface, taking into account the climatic factors that adversely affect HL processes, irrigation, the condition of ore stacks and the collecting capacity for pregnant and barren solutions in the evaporation of process solutions. Mathematical statistics and research data on respective standard and new methods are presented. It is confirmed that the ratio between the percentage of evaporation y and the wind speed x varies in the direct relationship of y = (a/x+b)+c, where a, b, and c are the coefficients characterizing the change in the ratios between the percentage of evaporation and the climatic data of the tropical area. Evaporation was shown to be more pronounced in the dry areas of Africa, where the daily summer temperature is above 50 °C (where the annual rainfall may be up to 100–200 mm). Direct irrigation sprinkler losses may reach 60 % of the total volume of the process solution pumped. When using pond irrigation, thermal exposure may lead to the daily evaporation of 5–13 mm of the solutions from the pond. The evaporation rate will be slightly less (1–4 %) when using drip irrigation. The effect of wind is especially pronounced when using the sprinkler irrigation technology in HL. It has been established that the active leaching area may be up to 40 % of the total precipitation collection area when the amount of precipitation in the water balance is 2.5 m per year. With increasing precipitation and lower evaporation rates, as well as to minimize respective losses, it is recommended to cover the side slopes with plastic.