Process for preparing magnetic carbon black

A process for preparing magnetic carbon black comprising carbon black and a magnetic fine particle dispersed and immobilized therein, which comprises the steps of:

• (A) burning a fuel to form a high temperature combustion gas stream containing free oxygen;
• (B) feeding, as a starting material for producing said carbon black, a hydrocarbon into the stream of said high temperature combustion gas to form carbon black;
• (C) at a point downstream of step B, feeding a gas comprising hydrogen and at least one transition metal compound of at least one of iron, cobalt and nickel into said high temperature combustion gas stream containing carbon black to form particulate magnetic carbon black;
• and
• (D) cooling the resulting reaction mixture and separating the particulate magnetic carbon black therefrom.

A process for preparing magnetic carbon black comprising carbon black and a magnetic fine particle dispersed and immobilized therein, which comprises the steps of:

• (A) burning a fuel to form a high temperature combustion gas stream;
• (B) feeding, as a starting material for producing said carbon black, a hydrocarbon into said high temperature combustion gas stream at two downstream locations, the hydrocarbon being converted to carbon black at these locations;
• (C) feeding at least one transition metal compound of at least one of iron, cobalt and nickel into said high temperature combustion gas stream at a location intermediate said two downstream locations to effect formation of particulate magnetic carbon black;
• and
• (D) cooling the resulting reaction mixture and separating the particulate magnetic carbon black therefrom.