Abstract: A production method for producing a particle mixture in which two or more types of particles are mixed, including a step of adding a first additive to first particles and mixing the first additive with the first particles using a first mixer and a step of introducing the two or more types of particles including the first particles mixed with the first additive and second particles into a blender container of a gravity blender, and mixing the two or more types of particles inside the blender container.

Abstract: Provided is a flexible container that can be easily opened. Provided is a flexible container for holding contents that includes an outer bag, an inner bag, a first binding member, and a lid. The outer bag includes a bottom surface portion in which a lower opening is formed. The inner bag is a tubular inner bag that is housed in the outer bag, configured to be filled with contents, and includes a discharge port portion. The discharge port portion forms a discharge path for discharging the contents and extends to a lower side of the bottom surface portion via the lower opening. The first binding member is tied around the discharge port portion to close the discharge path. The lid is attached to an outer side of the bottom surface portion to close the lower opening and cover the discharge port portion. The discharge port portion is narrowed to close the discharge path. The first binding member is tied around the discharge port portion to maintain a state in which the discharge port portion is narrowed.

Abstract: Provided is a production method with which a large amount of particle mixture in which two or more types of particles are mixed can be easily produced. The production method is for producing a particle mixture in which two or more types of particles are mixed, and includes the following steps (1) and (2): (1) a step of adding a first additive to first particles and mixing the first additive with the first particles using a first mixer; and (2) a step of introducing the two or more types of particles including the first particles mixed with the first additive and second particles into a blender container of a gravity blender, and mixing the two or more types of particles inside the blender container.