TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Method: The method further comprises: circulating purge gas about the growing ingot in the growth chamber so that the purge gas flows over the surface of the melt and exits through the annular space to sweep away silicon oxides from the melt; receiving the crystalline feedstock in the outer region; providing a conical heat shield including a base with downwardly depending walls extending into the growth chamber at an angle with respect to the ingot, where the walls tapering to a cone shape have a peripheral end, where the peripheral end has a smaller diameter than the base, defining an annular opening dimensioned for receiving the ingot drawn from the melt/ crystal interface; dimensioning the annular gap (205) to increase an outflow purge gas pressure to substantially restrict the entry of dust into the growth region; activating a vacuum to draw a stream of the purge gas through the annular gap from the inner growth region to the outer region; providing many heaters beneath the crucible; providing many heaters beneath the crucible in a radial pattern; and providing a weir and an inner weir disposed concentrically with the weir, where the inner weir have a lower height than the weir. The step of separating includes providing a weir supported on the base of the crucible, where the weir comprises cylindrical sidewalls extending vertically to a first height closely spaced apart from the heat shield, and the sidewalls have a portion extending further outwardly in substantially parallel concentric alignment with the adjacent heat shield to a second height, and the outwardly extending sidewalls define a closely spaced parallel concentric annular gap with respect to the heat shield. The step of directing the flow of purge gas away from the growing ingot and into the annular gap includes directing purge gas at a velocity to overcome entry of dust particles into the growth zone. The method includes dimensioning the annular gap of 5-20 mm in length. Preferred Components: The heat shield further comprises second downwardly depending walls disposed substantially parallel with the weir. The weir includes a devitrification promoter. The crucible has a wider aspect ratio than the weir. The weir and the inner weir each comprise a passageway (214) configured to allow the molten silicon to flow through it. The passageway of the weir and the passageway of the inner weir are offset with respect to one another. EXAMPLE - No suitable example given.