The present invention lies in the field of pyrometallurgy and discloses a process and a slag suitable for the recovery of Ni and Co from Li-ion batteries or their waste. The slag composition is defined according to:
10%<MnO<40%;
(CaO+1.5*Li.sub.2O)/Al.sub.2O.sub.3>0.3;
CaO+0.8*MnO+0.8*Li.sub.2O<60%;
(CaO+2*Li.sub.2O+0.4*MnO)/SiO.sub.22.0;
Li.sub.2O1%; and,
Al.sub.2O.sub.3+SiO.sub.2+CaO+Li.sub.2O+MnO+FeO+MgO>85%. This composition is particularly adapted to limit or avoid the corrosion of furnaces lined with magnesia-bearing refractory bricks.

A nickel alloy having superior surface properties by controlling the composition of non-metallic inclusions that affect surface properties, and a method for producing the same. A nickel alloy includes: all by mass %, Ni: 99.0% or more, C: 0.020% or less, Si: 0.01 to 0.3%, Mn: 0.3% or less, S: 0.010% or less, Cu: 0.2% or less, Al: 0.001 to 0.1%, Fe: 0.4% or less, O: 0.0001 to 0.0050% or less, Mg: 0.001 to 0.030%, Ca: 0.0001 to 0.0050%, B: 0.0001 to 0.01%, and the balance of inevitable impurities; the alloy including non-metallic inclusions, in which the non-metallic inclusions include one or more of MgO, CaO, CaOAl.sub.2O.sub.3-based oxides, CaOSiO.sub.2-based oxides, CaOMgO-based oxides, and MgO.Math.Al.sub.2O.sub.3, the MgO.Math.Al.sub.2O.sub.3 has a number ratio of number 50% or less with respect to all oxide-based, non-metallic inclusions.

A nickel alloy having superior surface properties by controlling the composition of non-metallic inclusions that affect surface properties, and a method for producing the same. A nickel alloy includes: all by mass %, Ni: 99.0% or more, C: 0.020% or less, Si: 0.01 to 0.3%, Mn: 0.3% or less, S: 0.010% or less, Cu: 0.2% or less, Al: 0.001 to 0.1%, Fe: 0.4% or less, O: 0.0001 to 0.0050% or less, Mg: 0.001 to 0.030%, Ca: 0.0001 to 0.0050%, B: 0.0001 to 0.01%, and the balance of inevitable impurities; the alloy including non-metallic inclusions, in which the non-metallic inclusions include one or more of MgO, CaO, CaOAl.sub.2O.sub.3-based oxides, CaOSiO.sub.2-based oxides, CaOMgO-based oxides, and MgO.Math.Al.sub.2O.sub.3, the MgO.Math.Al.sub.2O.sub.3 has a number ratio of number 50% or less with respect to all oxide-based, non-metallic inclusions.

A composition of non-metallic inclusions that affect surface properties and provides Ni-based alloys with superior surface properties. A Ni-based alloy consisting of: all by mass %, Ni: 52.0% or more, C: 0.001% to 0.030%, Si: 0.01 to 0.10%, Mn: 0.10 to 1.50%, P: 0.030% or less, S: 0.0050% or less, Cr: 13.0 to 25.0%, Mo: 10.0 to 18.0%, W: 1.00 to 5.00%, Cu: 1.00% or less, Co: 3.00% or less, Al: 0.001 to 0.170%, Fe: 2.00 to 8.00%, Mg: 0.0010 to 0.0200%, Ca: 0.0001 to 0.0040%, V: 0.500% or less, Nb: 0.001 to 0.100%, O: 0.0001 to 0.0050%, wherein the non-metallic inclusions includes one or more of MgO, CaO, CaOMgO-based oxides, CaOAl.sub.2O.sub.3MgO-based oxides, and MgO.Al.sub.2O.sub.3, the MgO.Al.sub.2O.sub.3 has number ratio of 50% or less with all oxide-based non-metallic inclusions.