Chemical action is an important factor for rock weathering in arid areas—Simulating experiments of evaporation and leaching

Abstract：Evaporation and leaching experiments were performed on two specimens of similar sulfide ores by using meteoric water in the same physico-chemical (normal temperature and pressure and oxidizing) environment to simulate weathering of rocks and ores in arid areas and humid areas. It took 603 days for the experiments. The experimental results show the following： appreciable changes took place in hardness, color and mineral composition of the specimen for the evaporation experiment, while the specimen for the leaching experiment in the main kept the features before the experiments in respect to the hardness, color and mineral composition. The pH values of the soaking liquid for the evaporation experiment first decreased, then increased and finally remained constant at 6.5-7; whereas the pH values of the leaching liquid for the leaching experiment first decreased and then was constant at ~5. However, cation concentrations in the soaking liquid were higher than those in the leaching liquid. The experimental results indicate that evaporation causes rock and ore weathering more easily than leaching. Evaporation is mainly a chemical reaction. So the experimental results are a stern challenge to the traditional idea that physical weathering predominates in arid areas.