Abstract: An apparatus and method to efficiently recover noble metals such as gold, silver and copper and aluminum from incineration ash, and effectively use ash after recovering the noble metals and others. An incineration ash treatment apparatus 1 including: a crusher for crushing an incineration ash A1 to be less or equal to 5 mm in maximum particle diameter, or/and a classifier for classifying an incineration ash to obtain an incineration ash whose maximum particle diameter is less or equal to 5 mm; an eddy current separator 8 for separating an incineration ash whose maximum particle diameter is less or equal to 5 mm discharged from the crusher or/and the classifier into a conductor E and a nonconductor I; a specific gravity separator for separating a conductor discharged from the eddy current separator 8 into a high gravity material H2 and a low gravity material L2. The specific gravity separator can be an air table 10.

Abstract: An apparatus and method to efficiently recover noble metals such as gold, silver and copper and aluminum from incineration ash, and effectively use ash after recovering the noble metals and others. An incineration ash treatment apparatus 1 including: a crusher for crushing an incineration ash A1 to be less or equal to 5 mm in maximum particle diameter, or/and a classifier for classifying an incineration ash to obtain an incineration ash whose maximum particle diameter is less or equal to 5 mm; an eddy current separator 8 for separating an incineration ash whose maximum particle diameter is less or equal to 5 mm discharged from the crusher or/and the classifier into a conductor E and a nonconductor I; a specific gravity separator for separating a conductor discharged from the eddy current separator 8 into a high gravity material H2 and a low gravity material L2. The specific gravity separator can be an air table 10.

Abstract: An AC arc welder which comprises means for detecting the welding current, a comparison circuit for generating logical output signals by comparing the output voltage or output current of the welding current detecting means with the reference voltage or reference current from a reference voltage generating means, digital means for generating logical output signals by performing adding operation or subtracting operation in response to the logical output signal, current supplying means for supplying the output current whose common ratio becoming the geometrical series of approximately m(m = 1, 2, 3 . . . ), and switching means for on and off- controlling the output of the current supplying means in response to the logical output signals of the digital means, thus forming a current feedback loop, whereby the output current from the current supplying means can be changed minutely, thus ensuring stabilized control characteristics.