Method for producing microparticles

A method for producing a microparticle, wherein

• at least two fluids to be processed are used,
• of these at least one fluid to be processed is a metal fluid having indium and/or a compound thereof and tin and/or a compound thereof dissolved in a solvent, and
• containing at least two metal elements of indium and tin in the metal fluid,
• at least one fluid to be processed other than the one fluid to be processed is a separating fluid which contains at least one reducing agent to separate an alloy that contains indium and tin,
• the said fluids to be processed are mixed in a thin film fluid formed between at least two processing surfaces which are disposed in a position they are faced with each other so as to be able to approach to and separate from each other, at least one of which rotates relative to the other, whereby separating a microparticle of an alloy that contains the indium and the tin, wherein in this method for producing the said microparticle,
• the separating fluid passes through between both the processing surfaces while forming the thin film fluid,
• providing a separate introduction path independent of a flow path that is the separating fluid is passed,
• at least one opening part leading to the separate introduction path is arranged in at least any one of the at least two processing surfaces,
• the metal fluid is introduced into between the at least two processing surfaces through the opening, whereby the metal fluid and the separating fluid are mixed in the thin film fluid, and
• the circumferential speed of the rotation at a converging point of the metal fluid and the separating fluid is controlled within the range of 0.8 to 41.9 m/second, thereby being molar ratio between indium and tin contained in the microparticle within ±20% relative to molar ratio between indium and tin contained in the metal fluid that is mixed in the thin film fluid.