BP <BP> UNIT TO BUILD GOLD EXTRACTION PLANT Amselco Minerals Inc, a unit of British Petroleum Co PLC, said it approved construction of a new plant with Nerco Minerals Co to process carbon ore to recover microscopic gold reserves. The plant, to be located at the Alligator Ridge Mine near Ely, Nev., will process 1,000 tons a day of carbon-bearing ore to recover 70,000 ounces of gold over three years, it said. The plant will use a chemical process called leaching to extract the residual gold, which could not otherwise be economically recovered. Operation of the plant, to be jointly owned by Amselco and Nerco, is set to start in October. The Alligator Ridge Mine is jointly owned by Amselco and Nerco, a unit of Nerco Inc <NER>, which is 90.5 pct owned by Pacificorp <PPW>, a Portland, Ore., holding company. The mine has produced about 60,000 ounces of gold a year since 1981 using another leaching process, a BP spokesman said. The open pit oxide ore reserves of Alligator Ridge will be exhausted by August 1987, as expected, when the work force will be reduced to about 72 from 127, the company said. The employees remaining after that will operate the new plant, it said.