Since World War II, pursuant to the program of rationalization of the copper industry, marked progress has been achieved in mineral flotation methods and conspicuous improvement seen in the production of sulfuric acid thru the utilization of waste smelter gas.<BR>In answer to this developments in mineral dressing methods and with a view to improve efficiency in the production of sulfuric acid utilizing waste smelter gas, the writer having studied the method for converting copper concentrates by direct charge into converters and for devicing means to improve the heat balance in the converter by external charge, has after a series of different tests arrived at the conclusion to utilize oxygen.<BR>(Test, using oxygen in bombs)<BR>As a first step and in order to determine the effectiveness of using oxygen, fourteen basic tests were conducted at the Saganoseki Smelter for one year, commercing May 1951 in conjunction with normal operations of the converters, during which approximately 5, 000 bombs of oxygen were consumed.<BR>(Test, using liquid oxygen)<BR>In the next. stage and with a view to commercialize this process, it was necessary to study operational conditions in detail, for which purpose tests were conducted on a commercial scale, for a period of two years, by installing a liquid oxygen producing unit of capacity 120l/hr and regulating large quantities of oxygen, as desired.<BR>In comparison with conventional blast furnace smelting methods the following merits are to be seen.<BR>(1) The stage of: preparatory treatment of fine concentrates can be eliminated.<BR>(2) Decreased requirements in fuel and fluxes.<BR>(3) Blister copper can be produced direct from the copper concentrates in one single stage operation.<BR>(4) The high SO content in the waste gas is best suited for the production of contact sulfuric acid.<BR>(5) Because'such impurities as lead can be easily removed, the copper content in the anodes is upgraded, which condition is more favorable during electroysis.<BR>In addition Ito these numerous, advantages, the utilization of iron concentrates recovered by dressing the converter slage, combined with the use of low cost oxygen produced in a low pressure air separating plant, it is feasible to<BR>(1) Reduce smelting costs<BR>(2) Improve yields<BR>(3) Recover untapped resources<BR>In other words it was possible to confirm that this new smelting process conforms with the three general principles enumerated above.