A device (1) for obtaining multicrystalline silicon, including: at least one crucible (3) made of quartz for the silicon, removably housed in a cup-shaped graphite container (4); a fluid-tight casing (5), including a fixed bottom half-shell (6) and a vertically mobile top half-shell (7); a top induction coil (12), set facing, with interposition of a graphite plate (14), the crucible, a lateral induction coil (16), set around a side wall (17) of the graphite container, and a bottom induction coil (18), set facing a bottom wall (19) of the graphite container and vertically mobile for varying the distance (D) from the bottom wall; and means (20) for a. c. electrical supply of the induction coils separately from one another; at least the lateral induction coil (16) includes a plurality of plane turns (13a...13e) set on top of one another, and means (25) for selectively short-circuiting, supplying or not supplying the turns, all together or separately one or more at a time and for varying the frequency of supply thereof all together or separately one or more at a time.