In Japan, many studies have been conducted to reduce the cost of mine drainage treatment at abandoned mines. The treatment method called "passive treatment" that utilizes natural purification and is expected to be applied to mine drainage treatment.Following the completion of the guidelines on the introduction of passive treatment, we conducted a simple screening focused on water quality, quantity and utilizable blank space to review the applicability of passive treatment to abandoned mines in Japan.Our findings indicate that passive treatment has the potential to be applied to many of abandoned mines in Japan, although there are still some issues to be solved.

The experimental results were analyzed by the advection diffusion model with multiple step-wise liquid flow pattern. As a result, the maximum liquid velocity was 3.8 times larger than the average velocity at the final stage of leaching while the maximum was 1.4 times larger than the average at the initial stage of leaching. These results indicate that the channeling is clear quantitatively and become larger with time.

JOGMEC has been carrying out the study on primary copper sulfide ores leaching for recovering copper economically and efficiently by heap leaching. In our study, we have been using the primary copper sulfide ore produced in an IOCG deposit. The ore is characterized by high iron content and high acid consumption in leaching. For the optimization of the leaching, the conditions such as ore size, agglomeration, pH and irrigation rate of leaching solution were examined with column leach tests. The best result was over 80 % extraction of copper in 150 days with leaching solution of 1 M sulfuric acid and temperature of 45 °C. In this experiment, the fines of the ore sample were removed before putting it into the column to keep the permeability of the ore bed. In these column leach tests, the Fe2+/total-Fe ratio of PLS decreased gradually by the activity of naturally grown iron-oxidizing bacteria. The bacteria in PLS, which have the ability of iron-oxidizing and sulfur-oxidizing, were identified by next-generation sequencing as Acidithiobacillus caldus and Sulfobacillus thermosulfidooxidans. We also carried out bench-scale tests with about 200 tons of the primary copper sulfide ores. Iron-oxidizing and sulfur-oxidizing bacteria were identified in the leaching solution as same with column leach tests. It is considered that the bacteria worked in the leaching solution and on the surface of the ores.