This section is from the book "An Elementary Outline Of Mechanical Processes", by G. W. Danforth. Also available from Amazon: An elementary outline of mechanical processes.
Nickel is produced from the arsenide, known as kupfer-nickel, and to a lesser extent from the sulphide.
The smelting process is somewhat complex and is accomplished by roasting, reducing in presence of flux, and Bessemerizing. The sulphide is then changed by roasting to oxide, which is finally reduced with charcoal.