Preprocessing method for solid material, and solid material product filled with solid material manufactured using said solid material preprocessing method

A method for preprocessing a solid material, the method comprising an impurity removal step of:

• heating a solid material which fills a solid material container at a temperature lower than the melting point of the solid material,
• removing at least part of the impurities contained in the solid material,
• heating the solid material which fills a solid material container at a temperature less than a phase transition point of the solid material, and
• sintering at least part or all of the solid material,
• wherein in the impurity removal step, a carrier gas having a predetermined flow rate is introduced into the solid material container, and in the sintering step no carrier gas is introduced into the solid material container,
• wherein the solid material container has a carrier gas introduction pipe which introduces the carrier gas into the solid material container, a first filling unit which is disposed inside the solid material container and is filled with the solid material, a second filling unit which is disposed on at least part of an outer circumference of the first filling unit and is filled with the solid material, at least one tray-shaped third filling unit which is disposed on a ceiling-side of the interior of the solid material container, a solid material discharge pipe which discharges the carrier gas with the accompanying solid material from the solid material container, and a heating unit which heats the solid material container, a carrier gas outlet of the carrier gas introduction pipe is provided to the first filling unit, an inlet of the solid material discharge pipe is provided to the third filling unit, and the carrier gas passes through the first filling unit, the second filling unit, and the third filling unit, in this order.