Spent nickel-containing base metal catalysts from chemical industry, crude oil refining, food and pharmaceutical industry are potential secondary raw materials for the recycling of nickel. Therefore, a bath smelting technology was developed for nickel-containing catalysts with organic residues of fat hardening and crude oil refining. With this process nickel matte is produced and further valuable metals like molybdenum and tungsten are enriched in a recyclable slag. The high energy content of the organic components is used for the smelting process. Consequently a considerable saving of energy and reduction of CO2 emissions would be reached.