Preheat the sample melting furnace to 960°C in advance, open the furnace door, and place the crucible at this time. The furnace temperature will drop to 860°C. Close the furnace door and continue to heat up. The temperature will rise to 940°C in about 15 minutes. Keep it warm for 10 minutes. Raise the temperature to 1150 degrees quickly. After the temperature reaches 1150 degrees, keep it for 10 minutes, then open the furnace door to take out the crucible.

Use a crucible fork to pour the liquid in the crucible into the steel film to cool down (when taking out the crucible, rotate the crucible steadily several times, and gently tap the steel film 2-3 times to make the lead beads attached to the wall Sink, then carefully pour all the melt into the cast iron mold). After cooling, the mold is lifted to separate the upper slag from the cone-shaped lead, and the slag is discarded. Obtain metal lead buttons enriched with precious metals.

(The formation of lead buttons: due to the high specific gravity of the lead alloy, it sinks to the bottom of the crucible. At the same time, the base metal oxides and gangue in the sample react with fluxes such as silica, borax, sodium carbonate, etc. Generate slag such as silicate or borate, which floats on it due to its small specific gravity, thereby separating the gold and silver from the sample), and place the poured crucible on the crucible storage cart.